CN112683652A - Method for testing critical bending angle of metal plate - Google Patents
Method for testing critical bending angle of metal plate Download PDFInfo
- Publication number
- CN112683652A CN112683652A CN202011451919.4A CN202011451919A CN112683652A CN 112683652 A CN112683652 A CN 112683652A CN 202011451919 A CN202011451919 A CN 202011451919A CN 112683652 A CN112683652 A CN 112683652A
- Authority
- CN
- China
- Prior art keywords
- test
- bending angle
- test sample
- closing threshold
- critical
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000012360 testing method Methods 0.000 title claims abstract description 112
- 238000005452 bending Methods 0.000 title claims abstract description 83
- 238000000034 method Methods 0.000 title claims abstract description 26
- 239000002184 metal Substances 0.000 title claims abstract description 22
- 230000003247 decreasing effect Effects 0.000 claims abstract description 13
- 238000010998 test method Methods 0.000 claims description 6
- 238000006073 displacement reaction Methods 0.000 claims description 5
- 238000004519 manufacturing process Methods 0.000 abstract description 5
- 239000000463 material Substances 0.000 abstract description 4
- 238000012827 research and development Methods 0.000 abstract description 3
- 230000000875 corresponding effect Effects 0.000 description 16
- 238000005259 measurement Methods 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 3
- 238000005336 cracking Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 241000283690 Bos taurus Species 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000008094 contradictory effect Effects 0.000 description 1
- 230000002596 correlated effect Effects 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 238000013001 point bending Methods 0.000 description 1
- 238000004154 testing of material Methods 0.000 description 1
- 238000012876 topography Methods 0.000 description 1
Images
Abstract
The invention discloses a method for testing a critical bending angle of a metal plate, which comprises the following steps: firstly, preparing a test sample; then, selecting a pressure head according to a preset corresponding relation, and inputting test parameters in the bending test device; further, setting an initial closing threshold of pressure applied by the indenter to the test specimen in the bend testing device; then, performing a bending test on the test sample according to a set initial closing threshold, calculating a corresponding initial bending angle at the moment, and observing whether the surface of the test sample cracks or not; finally, the initial closing threshold is increased or decreased until the critical bending angle of the test sample is obtained. The testing method provided by the invention can accurately measure the critical bending angle of the metal plate and is not limited by the strength level of the material; and the software and hardware of the existing test equipment do not need to be upgraded, so that the method is convenient to popularize and apply in enterprises and guides research and development and production.
Description
Technical Field
The invention relates to the technical field of metal material testing, in particular to a method for testing a critical bending angle of a metal plate.
Background
The metal plate is one of the section bars with large demand in industrial production, and is widely used in the industries of construction, maritime work, mechanical manufacturing and the like. In actual production, most of metal plates need to be subjected to mechanical processing processes such as cutting and bending, and due to the fact that the strength of the metal plates is relatively high, microcracks sometimes appear at bending positions in the bending process, and the cracks are expanded to form fractures in severe cases. In the actual forming process, the generation of microcracks is not beneficial to the forming of parts, in the bending process, the generation and development of microcracks can cause the failure of bending, and the existence of microcracks also influences the accuracy of material springback measurement. Therefore, it is necessary to predict the surface properties of the metal sheet, and to find the critical angle of the sheet in advance to avoid surface cracks during the machining process.
Therefore, for testing the bending angle when the crack of the curved outer surface of the sample is initiated, namely the critical bending angle, a Digital Image Correlation (DIC) strain measurement technology begins to appear in the prior art, as shown in FIG. 1, the technology utilizes a reverse three-point bending device and is combined with a DIC system for real-time monitoring until the camera shoots that the crack of the curved outer surface of the sample automatically stops testing, and the bending angle at the moment is the critical bending angle. However, although the method can predict the cracking of the plate by measuring the bending angle and the corresponding main strain when the crack is initiated, the DIC strain measurement technology is based on the result calculated by the image data shot by the DIC system, so that the requirements on software and hardware are very high, the equipment cost is high, and the method is not convenient to popularize and apply; in addition, the calculation result is influenced by the data processing mode and has larger deviation with the manual measurement result.
Disclosure of Invention
The invention mainly aims to provide a method for testing a critical bending angle of a metal plate, and aims to solve the technical problem.
In order to achieve the purpose, the test method for the critical bending angle of the metal plate, which is provided by the invention, is applied to a bending test device, the device comprises a pressure head and two support rollers arranged in parallel with a gap, the pressure head is vertically arranged above the gap of the support rollers, and the test method comprises the following steps:
preparing a test sample;
selecting a pressure head according to a preset corresponding relation, and inputting test parameters in the bending test device;
setting an initial closing threshold for the pressure applied by the indenter to the test specimen in the bend testing device;
performing a bending test on the test sample according to a set initial closing threshold, calculating a corresponding initial bending angle at the moment, and observing whether the surface of the test sample cracks or not;
increasing or decreasing the initial closing threshold until a critical bend angle of the test sample is obtained.
Preferably, the test parameters include the roller radius, the sample thickness, and the roller distance.
Preferably, the bending angle is calculated by the following formula:
wherein, R: the radius of the support roller; a: the thickness of the sample; s: the displacement of a pressure head; l: the distance of the support rollers.
Preferably, in the step of increasing or decreasing the initial closing threshold until the critical bending angle of the test sample is obtained, the method specifically includes:
if the surface of the test sample cracks, reducing the initial closing threshold value, setting a first closing threshold value to continue the bending test, calculating a corresponding first bending angle at the moment, and observing whether the surface of the test sample cracks or not;
and if the surface of the test sample is cracked, repeating the previous step until the surface of the test sample is not cracked, and calculating the corresponding critical bending angle.
Preferably, in the step of increasing or decreasing the initial closing threshold until the critical bending angle of the test sample is obtained, the method specifically includes:
if the surface of the test sample is not cracked, increasing the initial closing threshold, setting a second closing threshold to continue the bending test, calculating a corresponding second bending angle at the moment, and observing whether the surface of the test sample is cracked;
and if the surface of the test sample is not cracked, repeating the previous step until the surface of the test sample is cracked, and calculating the critical bending angle corresponding to the closing threshold set at the previous time.
In the technical scheme of the invention, the method for testing the critical bending angle of the metal plate comprises the following steps: firstly, preparing a test sample; then, selecting a pressure head according to a preset corresponding relation, and inputting test parameters in the bending test device; further, setting an initial closing threshold of pressure applied by the indenter to the test specimen in the bend testing device; then, performing a bending test on the test sample according to a set initial closing threshold, calculating a corresponding initial bending angle at the moment, and observing whether the surface of the test sample cracks or not; finally, the initial closing threshold is increased or decreased until the critical bending angle of the test sample is obtained. The testing method provided by the invention can accurately measure the critical bending angle of the metal plate and is not limited by the strength level of the material; and the software and hardware of the existing test equipment do not need to be upgraded, so that the method is convenient to popularize and apply in enterprises and guides research and development and production.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.
FIG. 1 is a schematic diagram of a testing apparatus used in a conventional DIC strain measurement technique;
fig. 2 is a schematic diagram of a testing apparatus used in an embodiment of the invention.
FIG. 3 is a surface topography of a critical bending test of a metal plate in an embodiment of the present invention.
Wherein, F: testing force; s: the displacement of a pressure head; l: distance between the support rollers; d: the diameter of the support roller; i: the length of the sample; b: width of the sample.
The implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that all the directional indicators (such as up, down, left, right, front, and rear … …) in the embodiment of the present invention are only used to explain the relative position relationship between the components, the movement situation, etc. in a specific posture (as shown in the drawing), and if the specific posture is changed, the directional indicator is changed accordingly.
In addition, the descriptions related to "first", "second", etc. in the present invention are only for descriptive purposes and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.
In addition, the technical solutions in the embodiments of the present invention may be combined with each other, but it must be based on the realization of those skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination of technical solutions should not be considered to exist, and is not within the protection scope of the present invention.
Referring to fig. 2, in an embodiment of the present invention, a method for testing a critical bending angle of a metal plate is applied to a bending testing apparatus, the apparatus includes a press head and two support rollers arranged in parallel with a gap, the press head is vertically arranged above the gap of the support rollers, and the testing method includes the following steps: firstly, preparing a test sample; then, selecting a pressure head according to a preset corresponding relation, and inputting test parameters in the bending test device; further, setting an initial closing threshold of pressure applied by the indenter to the test specimen in the bend testing device; then, performing a bending test on the test sample according to a set initial closing threshold, calculating a corresponding initial bending angle at the moment, and observing whether the surface of the test sample cracks or not; finally, the initial closing threshold is increased or decreased until the critical bending angle of the test sample is obtained.
The test method provided by the embodiment can accurately measure the critical bending angle of the metal plate and is not limited by the strength level of the material; and the software and hardware of the existing test equipment do not need to be upgraded, so that the method is convenient to popularize and apply in enterprises and guides research and development and production.
Specifically, the test parameters comprise a support roller radius, a sample thickness and a support roller distance.
The bending angle is calculated by the following formula:
wherein, R: the radius of the support roller; a: the thickness of the sample; s: the displacement of a pressure head; l: the distance of the support rollers.
It should be noted that the closing threshold and the ram displacement S are positively correlated in this embodiment, and therefore they may be replaced with each other.
Specifically, in the step of increasing or decreasing the initial closing threshold until the critical bending angle of the test sample is obtained, the method specifically includes: if the surface of the test sample cracks, reducing the initial closing threshold value, setting a first closing threshold value to continue the bending test, calculating a corresponding first bending angle at the moment, and observing whether the surface of the test sample cracks or not; and if the surface of the test sample is cracked, repeating the previous step until the surface of the test sample is not cracked, and calculating the corresponding critical bending angle.
Preferably, in the step of increasing or decreasing the initial closing threshold until the critical bending angle of the test sample is obtained, the method specifically includes: if the surface of the test sample is not cracked, increasing the initial closing threshold, setting a second closing threshold to continue the bending test, calculating a corresponding second bending angle at the moment, and observing whether the surface of the test sample is cracked; and if the surface of the test sample is not cracked, repeating the previous step until the surface of the test sample is cracked, and calculating the critical bending angle corresponding to the closing threshold set at the previous time.
In summary, the critical bending angle is gradually approached by adjusting the closing threshold. The approach mode of gradually increasing or decreasing the closing threshold value can be selected, when the closing threshold value is close to the critical value, the closing threshold value is alternately increased or decreased until the critical value is measured, and the test quantity is determined according to the selected step length. For example, the bending angle is tested under the closing threshold values of 20N, 40N, 60N and 80N in sequence, the sample is taken down and observed, if cracks are visible only under 80N, the range is narrowed, and the test is carried out under 70N until a critical closing threshold value is detected (cracks are observed beyond the value), and the bending angle measured under the critical closing threshold value is the critical bending angle.
TABLE 1
The test method is simply illustrated by combining the experimental results of fig. 3 and table 1: setting an initial closing threshold value at 100N (cattle), calculating a bending angle at the moment to be 94.4 degrees, and cracking on the surface of the sample; gradually reducing the closing threshold value, calculating the corresponding bending angle and observing the surface morphology of the sample, wherein when the closing threshold value is set at 20N, unobvious microcracks appear on the surface of the sample, so that the reduction range of the closing threshold value can be properly reduced, and finally when the closing threshold value is set at 15N, the surface of the sample is not cracked, and the bending angle at the moment is the critical bending angle of 86.0 degrees of the metal plate.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention, and all modifications and equivalents of the present invention, which are made by the contents of the present specification and the accompanying drawings, or directly/indirectly applied to other related technical fields, are included in the scope of the present invention.
Claims (5)
1. A test method for a critical bending angle of a metal plate is applied to a bending test device, the device comprises a pressure head and two support rollers arranged in parallel with a gap, the pressure head is vertically arranged above the gap of the support rollers, and the test method is characterized by comprising the following steps:
preparing a test sample;
selecting a pressure head according to a preset corresponding relation, and inputting test parameters in the bending test device;
setting an initial closing threshold for the pressure applied by the indenter to the test specimen in the bend testing device;
performing a bending test on the test sample according to a set initial closing threshold, calculating a corresponding initial bending angle at the moment, and observing whether the surface of the test sample cracks or not;
increasing or decreasing the initial closing threshold until a critical bend angle of the test sample is obtained.
2. The method for testing the critical bending angle of the metal plate according to claim 1, wherein the test parameters comprise a support roller radius, a sample thickness and a support roller distance.
3. The method for testing the critical bending angle of the metal plate according to claim 2, wherein the bending angle is calculated by the following formula:
wherein, R: the radius of the support roller; a: the thickness of the sample; s: the displacement of a pressure head; l: the distance of the support rollers.
4. The method for testing the critical bending angle of the metal plate according to claim 1, wherein in the step of increasing or decreasing the initial closing threshold until the critical bending angle of the test sample is obtained, the method specifically comprises:
if the surface of the test sample cracks, reducing the initial closing threshold value, setting a first closing threshold value to continue the bending test, calculating a corresponding first bending angle at the moment, and observing whether the surface of the test sample cracks or not;
and if the surface of the test sample is cracked, repeating the previous step until the surface of the test sample is not cracked, and calculating the corresponding critical bending angle.
5. The method for testing the critical bending angle of the metal plate according to claim 1, wherein in the step of increasing or decreasing the initial closing threshold until the critical bending angle of the test sample is obtained, the method specifically comprises:
if the surface of the test sample is not cracked, increasing the initial closing threshold, setting a second closing threshold to continue the bending test, calculating a corresponding second bending angle at the moment, and observing whether the surface of the test sample is cracked;
and if the surface of the test sample is not cracked, repeating the previous step until the surface of the test sample is cracked, and calculating the critical bending angle corresponding to the closing threshold set at the previous time.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011451919.4A CN112683652A (en) | 2020-12-10 | 2020-12-10 | Method for testing critical bending angle of metal plate |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011451919.4A CN112683652A (en) | 2020-12-10 | 2020-12-10 | Method for testing critical bending angle of metal plate |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN112683652A true CN112683652A (en) | 2021-04-20 |
Family
ID=75448860
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202011451919.4A Pending CN112683652A (en) | 2020-12-10 | 2020-12-10 | Method for testing critical bending angle of metal plate |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN112683652A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113790977A (en) * | 2021-08-10 | 2021-12-14 | 武汉钢铁有限公司 | Method for measuring ultimate bending fracture strain of metal plate |
| CN114527010A (en) * | 2021-12-17 | 2022-05-24 | 浙江瑞凯不锈钢股份有限公司 | Bending strength detection device for cold-rolled stainless steel strip |
Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN201355332Y (en) * | 2008-09-24 | 2009-12-02 | 攀钢集团研究院有限公司 | Pressure head for bend test of metal materials |
| CN103345558A (en) * | 2013-07-08 | 2013-10-09 | 中联重科股份有限公司 | Method and system for controlling bending of high-strength steel |
| CN206683933U (en) * | 2017-03-24 | 2017-11-28 | 张家港康得新光电材料有限公司 | A kind of bending angle test device |
| CN108776070A (en) * | 2018-07-06 | 2018-11-09 | 中国建材检验认证集团股份有限公司 | Tubing coating bending strength test method |
| CN109784000A (en) * | 2019-03-20 | 2019-05-21 | 福建省特种设备检验研究院 | A kind of crane wheel pressure detection method based on plastic deformation |
| CN110487653A (en) * | 2019-09-05 | 2019-11-22 | 首钢集团有限公司 | A kind of surface quality of high-strength steel steel plate bending and strain stress relation test method |
| DE102020112021A1 (en) * | 2019-05-08 | 2020-11-12 | Beijing Institute Of Technology | Method for determining the mapping relationship between the fatigue crack initiation position and the surface integrity of a component |
-
2020
- 2020-12-10 CN CN202011451919.4A patent/CN112683652A/en active Pending
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN201355332Y (en) * | 2008-09-24 | 2009-12-02 | 攀钢集团研究院有限公司 | Pressure head for bend test of metal materials |
| CN103345558A (en) * | 2013-07-08 | 2013-10-09 | 中联重科股份有限公司 | Method and system for controlling bending of high-strength steel |
| CN206683933U (en) * | 2017-03-24 | 2017-11-28 | 张家港康得新光电材料有限公司 | A kind of bending angle test device |
| CN108776070A (en) * | 2018-07-06 | 2018-11-09 | 中国建材检验认证集团股份有限公司 | Tubing coating bending strength test method |
| CN109784000A (en) * | 2019-03-20 | 2019-05-21 | 福建省特种设备检验研究院 | A kind of crane wheel pressure detection method based on plastic deformation |
| DE102020112021A1 (en) * | 2019-05-08 | 2020-11-12 | Beijing Institute Of Technology | Method for determining the mapping relationship between the fatigue crack initiation position and the surface integrity of a component |
| CN110487653A (en) * | 2019-09-05 | 2019-11-22 | 首钢集团有限公司 | A kind of surface quality of high-strength steel steel plate bending and strain stress relation test method |
Non-Patent Citations (2)
| Title |
|---|
| 刘向东,高丽华: "影响冷弯型钢临界弯曲半径因素综合分析", 淮海工学院学报, vol. 6, no. 04 * |
| 德国汽车协会VDA: "德国汽车协会Plate bending test for metallic materials", vol. 238, pages: 5 - 9 * |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113790977A (en) * | 2021-08-10 | 2021-12-14 | 武汉钢铁有限公司 | Method for measuring ultimate bending fracture strain of metal plate |
| CN114527010A (en) * | 2021-12-17 | 2022-05-24 | 浙江瑞凯不锈钢股份有限公司 | Bending strength detection device for cold-rolled stainless steel strip |
| CN114527010B (en) * | 2021-12-17 | 2022-09-16 | 浙江瑞凯不锈钢股份有限公司 | Anti-bending strength detection device for cold-rolled stainless steel strip |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Ranta-Eskola | Use of the hydraulic bulge test in biaxial tensile testing | |
| JP5170089B2 (en) | Thin plate press forming apparatus and press forming method | |
| JP5294082B2 (en) | Bending limit strain measurement method, bending crack determination method, and bending crack determination program | |
| CN112683652A (en) | Method for testing critical bending angle of metal plate | |
| CN111896373B (en) | Test and calculation method for determining equivalent plastic strain forming limit diagram | |
| CN111157157A (en) | Cold-rolled sheet residual stress prediction and measurement method | |
| CN103969128A (en) | Method for detecting bending mechanical property of sample | |
| Arola et al. | Digital image correlation and optical strain measuring in bendability assessment of ultra-high strength structural steels | |
| CN101699259B (en) | Method for simulating bent pipe deformation by bending | |
| Zhang et al. | An analytical model for predicting sheet springback after V-bending | |
| CN105675406A (en) | High-temperature bending detection method of metal material | |
| CN102494959A (en) | Method for automatically measuring elongation rate of metal test sample under high temperature state | |
| CN116738780B (en) | Compact tensile sample fatigue crack propagation length and rate calculation method considering crack deflection | |
| CN106769439B (en) | A kind of test method of line steel hot rolling roll bending yield strength | |
| JP7327595B1 (en) | METHOD AND DEVICE FOR ACQUIRING FORMING LIMIT OF METAL PLATE | |
| Amaro et al. | CTOA testing of pipeline steels using MDCB specimens | |
| RU2333471C2 (en) | Punch-device for testing and method of testing of sheet material for springback and capacity at double-angle bending (versions) | |
| WO2022123825A1 (en) | Method for calculating residual stress | |
| CN112345379A (en) | Testing device and testing method for bending resilience characteristic of plate | |
| Dokšanović et al. | Stress–strain relationships and influence of testing parameters on coupon test results | |
| CN111508572A (en) | Method for determining plane stress fracture toughness of metal material | |
| Ruoppa et al. | Bendability tests for ultra-high-strength steels with optical strain analysis and prediction of bending force | |
| JP2009095877A (en) | Apparatus and method for press-forming sheet metal | |
| CN105865936B (en) | The low-temperature bending detection method of metal material | |
| JP7464176B1 (en) | Method, device and program for determining press-molded cracks, and method for manufacturing press-molded products |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| RJ01 | Rejection of invention patent application after publication |
Application publication date: 20210420 |