CN113560817B - Hot rolled steel plate blanking shearing method - Google Patents
Hot rolled steel plate blanking shearing method Download PDFInfo
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- CN113560817B CN113560817B CN202110780960.4A CN202110780960A CN113560817B CN 113560817 B CN113560817 B CN 113560817B CN 202110780960 A CN202110780960 A CN 202110780960A CN 113560817 B CN113560817 B CN 113560817B
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Abstract
A blanking shearing method of a hot rolled steel plate relates to metal material processing, wherein the tensile strength of the steel plate is 260-1200MPa, and the thickness t of the steel plate is 0.7-20.0mm; it is characterized in that the clearance between the cutting edges is 1.0-6.0%t. According to the strength and thickness of the sheared steel plate, the gap value of the shearing edge corresponds to the strength and thickness of the sheared steel plate, so that the proportion of the bright area of the shearing surface of the steel plate is more than 20%, no obvious burrs exist, the subsequent part processing cracking rate is greatly reduced, and the material utilization rate is improved. Meanwhile, the production efficiency is improved, and the production cost is reduced.
Description
Technical Field
The invention relates to the technology of the field of metal material processing application, in particular to a method for improving the shearing quality by setting the gap of the shearing edge of a plate shearing machine according to the strength and the thickness of a sheared steel plate when blanking and shearing a hot rolled steel plate.
Background
Along with the development of economy and society and the progress of scientific technology, the resource development and conservation concept is deepened, the utilization rate of various materials in production and manufacture is improved, and the sustainable life style of green and environmental protection is advocated to be deep. The method relates to the processing and application of huge hot rolled steel plates in the field of industrial manufacturing, and along with the promotion of lightweight technology, the strength of newly developed steel materials is higher and higher, blanking and shearing before steel plate forming processing are harder and harder, the shearing mode and shearing surface quality directly influence the final utilization rate of materials, the service life of manufactured parts is prolonged, and the key point of whether advanced materials really exert the advantages of the advanced materials is that.
The traditional method for blanking and shearing the hot-rolled steel plate is mechanical shearing of a plate shearing machine, has the advantages of convenience, rapidness, high production efficiency, low energy consumption, no pollution, complete industrial foundation, quick popularization and the like, and is more suitable for popularization in the field of hot-rolled steel plate processing with a large range. The blanking shearing of steel materials in the field of industrial manufacturing can be met by improving and improving the operation mode and the specification of the plate shearing machine, and particularly, the high-strength thick-specification hot rolled steel products can be met.
In recent years, new blanking methods such as laser cutting, plasma cutting, water cutting and the like are also appeared in the processing mode, and the method has great benefits for improving the quality of the blanking shearing surface of the hot rolled steel plate, but the common defects of the methods are that the cost is too high, the energy consumption is high, the efficiency is low, the application places are limited and the like, and the method cannot be popularized.
The manufacturing process of the steel part is a production process with multiple and complex procedures, and the procedures can be simply divided into two main procedures of forming and blanking separation. The forming process refers to a process of changing the shape and structure of the steel material by external force, such as flanging, bending, stamping, etc., by utilizing the ductility of the steel material. The blanking and separating process is to remove redundant materials, and provide plates with accurate dimensions for the forming process, such as shearing blanking, grinding, edge planing and the like.
Disclosure of Invention
In order to improve the utilization rate of materials and avoid influencing the strength and the service life of the materials due to separation, the invention provides a blanking shearing method for hot rolled steel plates, which is accurate in shearing blanking, grinding and edge planing.
The technical scheme of the invention is as follows: a blanking shearing method of a hot rolled steel plate, wherein the tensile strength of the hot rolled steel plate is 260-1200MPa, and the thickness of the hot rolled steel plate is 0.7-20.0mm; the cutting sequence is a round angle area, a bright area, a cracking area and burrs;
the hot rolled steel plate is divided into 4 strength grades according to industry habit and experience, and each strength grade is further divided into 4-6 thickness grades according to specifications for research. Then, a comparison test is performed on each hot rolled plate with a specific strength grade and thickness grade by using a variable shear gap, and analysis and comparison are performed, so that an optimal gap value is preferable.
The quality of the shearing surface is evaluated according to the proportion of the fillet area, the bright area, the cracking area and the burrs on the shearing surface and the surface flatness; the quality of the shearing surface is evaluated by means of a detection device, a microscope is usually used for observing the microscopic morphology and microstructure, and a stretcher is used for measuring the mechanical property change to evaluate the rationality of the shearing gap setting.
1. Visual inspection example:
the shearing section forms four characteristic areas of a round angle area, a bright area, a cracking area and burrs according to the sequence of the shearing process.
The fillet area is also called corner collapse, and is an area with a certain fillet, called fillet area, which is formed easily when a sheet material is extruded by a shear blade and forces the internal tissue of the metal to flow. The fillet area has no obvious influence on the processing and forming, but the deformation degree and the size influence the appearance shape and the dimensional accuracy of the shearing surface.
The bright area is an area with smooth and flat surface formed by extruding the plate in the horizontal direction of the shearing edge. The smooth and bright surface is called a bright area. The surface quality is the most flat part in the whole shearing surface, so that the proportion of the bright area in the whole shearing surface is increased as much as possible in shearing, and the forming is facilitated.
The fracture zone is also known as the fracture zone: the crack is formed after meeting in crack extension caused by upper and lower shearing blades, and is called as a cracking zone, the surface of the crack is rough and is unfavorable for forming, the proportion of the cracking zone in the whole shearing surface is reduced as much as possible in shearing, and the cracking of a part caused by the cracking zone in forming is avoided.
The burrs are not formed at the contact position of the plate and the cutting edge, but formed at a certain distance from the advancing direction of the cutting edge, the cracks are continuously grown under the action of external force, and the plate is completely broken to form a bulge with a certain thickness. It is also disadvantageous for the subsequent formation of the material, and the generation of burrs should be minimized.
In short, the ratio of the four characteristic regions in the whole shearing surface is observed by naked eyes by a visual inspection method, and the larger the ratio of the bright region is, the better the shearing quality is, and the forming is beneficial, otherwise, the larger the ratio of the rupture region and the burr region is, the worse the shearing quality is, and the forming is not beneficial.
2. Examples of quantitative assays:
the effect of the shearing gap on the crack sensitivity of the hot rolled steel sheet was examined for steel sheets of a specific strength and thickness (the tensile strength Rm of the sample is 745MPa, the thickness t is 5.0 mm) at the time of the test, with the gaps set at 2%t, 5%t, 6.6% t, 10% t, 15% t. The law of the strain is quantitatively studied from morphology, tissue and shear tensile property changes.
(1) Influence of the gap on the shear morphology
The width of the clear zone increases significantly with increasing shear gap, as does the shear area. The increase in the shearing area is caused by the generation of burrs. The bright area was also seen to increase, indicating that the bright area of the steel plate increased with increasing gap in the range 2%t-15%. In addition, it was found that burrs grow rapidly when the gap is 10% t or more, indicating that the gap is too large, resulting in a decrease in shearing quality, and therefore, the gap should be controlled to be 10% t or less for the steel sheet.
(2) Effect of gap on shear plane tissue
And respectively observing the tissue characteristics of the fillet area, the bright area and the cracking area under different clearance conditions by using a scanning electron microscope. Three shearing conditions of 2%t, 6.6% t and 15% t were selected for observation, respectively.
2%t, 6.6% t and 15% t of the structure of the fillet area under the three gaps found that a small number of micro-holes were generated in the fillet area. By comparing the microstructure patterns of the bright area and the broken area under different gaps, micro holes are generated under the condition of 3 gaps, but the smaller the gaps are, the smaller the number and the size of the micro holes are. This means that in the range of 2%t to 15% t, the smaller the gap, the fewer crack sources that initiate cracking, and the better formability.
(3) Effect of gap on shear tensile Properties
To examine the effect rule of shear on the tensile properties of the material obtained under 2%t, 5%t, 6.6% t, 10% t, 15% t 5 different gap conditions, the tensile test specimen was sized as a half-tensile test specimen. The straight edge is a sheared edge during processing, and other edges are processed by linear cutting and polished, so that the influence of cutting on a sample is eliminated.
The shear quality was evaluated using the load displacement curve of the tensile test, and for convenience of comparison, a sample polished after linear cutting also with the 6 th straight edge was also introduced, and the sample was regarded as a standard sample completely free from the influence of the shear gap. The load levels of the 6 samples did not change much, but the displacement increased with decreasing shear gap. Again, it was demonstrated that the steel plate shear gap should be controlled within 10% t, with a shear gap of 2%t being optimal for the strength and thickness of the steel plate tested.
From the above experimental comparison, the following conclusions can be drawn: the blanking shearing method of the hot rolled steel plate is characterized in that when the shearing blade clearance of the hot rolled steel plate with the intensity of 260-1200MPa and the thickness specification of 0.7-20.0mm is set to be 1.0-6% t during blanking shearing, the bright area of the shearing surface of the steel plate accounts for more than 20% and no obvious burrs exist, the subsequent cold forming such as bending, stamping, flanging and the like is ensured to be free from cracking, and the utilization rate of materials is greatly improved.
The material utilization rate (part qualification rate) of the invention is improved by 15%; compared with the laser cutting method, the production efficiency of the invention is more than 12 times of that of the laser cutting method, and the average electric energy is saved by 25 yuan/ton.
The strength and thickness of the hot rolled steel plate are measured before shearing, the measurement results of at least three different positions are averaged, and according to the measurement results of the strength and the thickness, the cutting edge material of the plate shearing machine is selected and the cutting edge clearance is set.
Detailed Description
The following describes the embodiments of the present invention in detail with reference to examples, but the embodiments of the present invention are not limited to the examples described below.
Example 1
I confirmation of the object to be processed
The thickness specification of the hot rolled carbon structural steel Q235B is 3.0mm, and the strength and the thickness of a sheared object (the strength can also be converted and calculated simply and conveniently by measuring the hardness) are measured and verified correspondingly before shearing. The measurement result was that the tensile strength was 475MPa and the thickness was 2.97mm. If the steel plate is a whole steel plate, the strength and thickness values marked on the attached quality assurance certificate can be referred to when the steel plate leaves the factory, and repeated measurement is not needed.
II parameter setting for plate shearing machine
According to the measured steel plate strength value 475MPa and thickness value 2.97mm in the previous step, the corresponding strength and thickness in the table 1, namely the table for reference clearance between shearing edges of the plate shearing machine, are corresponding to the 5 th row of serial numbers, the reference value of clearance between shearing edges is 1.0 t-1.2%t, and the clearance is set to be 0.03mm.
III trimming determination
Starting the plate shearing machine to perform trial shearing, observing whether burrs exist in the bright area of the shearing section accounting for the proportion of the total section, and if the proportion of the bright area is more than 20%, no obvious burrs exist, and shearing is not needed to be adjusted; if the proportion of the bright area is less than 20%, or the clearance between the shearing edges is finely adjusted in a small direction by obvious burrs, repeating the steps until the clearance is proper.
Example two
I confirmation of the object to be processed
The thickness specification of the hot rolled low alloy structural steel Q460C is 10.0mm, and the strength and the thickness of a sheared object (the strength can be converted and calculated simply and conveniently by measuring the hardness) are measured and verified correspondingly before shearing. The measurement result was 650MPa of tensile strength and 9.95mm of thickness. If the steel plate is a whole steel plate, the strength and thickness values marked on the attached quality assurance certificate can be referred to in the factory, and repeated measurement is not needed.
II parameter setting for plate shearing machine
The corresponding strength and thickness in Table 1 are compared with those in line 7 according to the measured steel plate strength value 650MPa and thickness value 9.95mm in the previous step, the shearing edge clearance reference value is 1.4 t-2.5% t, and the clearance is set to 0.20mm.
III trimming determination
Starting the plate shearing machine to perform trial shearing, observing the proportion of the bright area of the shearing section in the total section, and if the proportion of the bright area is more than 20%, no obvious burrs are generated, and shearing is not required to be adjusted; if the proportion of the bright area is less than 20%, or the clearance between the shearing edges is finely adjusted in a small direction by obvious burrs, repeating the steps until the clearance is proper.
Table 1 shear blade gap reference table for plate shearing machine
Note that: in the table, rm represents the tensile strength of the steel plate, and t represents the thickness of the steel plate.
Claims (1)
1. A blanking shearing method of a hot rolled steel plate, wherein the tensile strength of the steel plate is 260-1200MPa, and the thickness of the steel plate is 0.7-20.0mm; the clearance between the shearing edges is 1.0-6.0% t;
it is characterized in that when 260 is less than or equal to Rm is less than or equal to 330, any one of the following is selected:
(1) T is more than or equal to 0.7 and less than or equal to 3.0, and the clearance between the cutting edges is 1.0-1.5% t;
(2) 3.0< t is less than or equal to 12.7, and the clearance between the cutting edges is 1.5-2.5% t;
(3) 12.7< t is less than or equal to 16.5, and the clearance between the cutting edges is 2.5 to 3.5 percent t;
(4) 16.5< t is less than or equal to 20.0, and the clearance between the cutting edges is 4.5 to 6.0 percent t;
when 330< Rm is less than or equal to 700, any one of the following is selected:
（1）0.7≤t≤3.0，1.0-1.2% t；
（2）0<t≤8.0，1.2-1.5% t；
（3）0<t≤14.5，1.4-2.5% t；
（4）14.5<t≤16.5，2.5-3.0% t；
（5）16.5<t≤20.0，3.0-5.0% t；
when 700< Rm is less than or equal to 1000, any one of the following is selected:
（1）0.7≤t≤2.5，1.0-1.2% t；
（2）2.5<t≤5.0，1.2-1.5% t；
（3）5.0<t≤12.7，1.4-2.5% t；
（4）12.7<t≤15.5，2.0-3.0% t；
（5）15.5<t≤17.0，3.0-3.5% t；
（6）17.0<t≤20.0，3.5-4.5% t；
when Rm is 1000< 1200; any one of the following is selected:
（1）0.7≤t≤1.5， 1.5-2.0% t；
（2）1.5<t≤6.0， 2.0-2.5% t；
（3）6.0<t≤10.0， 2.3-2.5% t；
（4）10.0<t≤15.0，2.4-3.0% t；
（5）15.0<t≤17.0，3.0-3.3% t，
（6）17.0<t≤20.0；3.2-4.0% t；
rm represents the tensile strength of the steel plate, the unit is MPa, t is the thickness of the steel plate, and the unit is mm.
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| CN2785771Y (en) * | 2005-02-02 | 2006-06-07 | 金荣范 | Circular shear blade for circular shears |
| JP4815913B2 (en) * | 2005-07-19 | 2011-11-16 | Ｊｆｅスチール株式会社 | Method for preventing shear cracking of thick steel plates |
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Non-Patent Citations (5)
| Title |
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| 中厚板圆盘剪剪切力能参数测试及最佳剪刃间隙数学模型的建立;马立峰;黄庆学;黄志权;楚志兵;韩贺永;;工程设计学报(第06期) * |
| 圆盘剪剪切工艺优化研究;陈东文;黄贞益;郝震宇;许体武;章小峰;;轧钢(第02期) * |
| 基于正交试验设计与有限元仿真的板材剪切力影响因素研究;杨捷艳;袁明清;;现代机械(第01期) * |
| 滚切式剪机剪刃间隙调整经验公式的探讨;张永生,黄远坚;南方金属(第06期) * |
| 钢板高质量剪切工艺的研究及生产应用;杨占廷;梁立辉;;酒钢科技(第Z1期) * |
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