CN113560817A - Blanking and shearing method for hot rolled steel plate - Google Patents
Blanking and shearing method for hot rolled steel plate Download PDFInfo
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- CN113560817A CN113560817A CN202110780960.4A CN202110780960A CN113560817A CN 113560817 A CN113560817 A CN 113560817A CN 202110780960 A CN202110780960 A CN 202110780960A CN 113560817 A CN113560817 A CN 113560817A
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- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
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- B23P15/00—Making specific metal objects by operations not covered by a single other subclass or a group in this subclass
Abstract
A blanking and shearing method for a hot rolled steel plate relates to the processing of metal materials, wherein the tensile strength of the steel plate is 260-1200MPa, and the thickness t of the steel plate is 0.7-20.0 mm; it is characterized in that the clearance between the cutting edges is 1.0-6.0% t. According to the invention, the gap value of the shearing edge is corresponded according to the strength and the 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 burr exists, 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 technical field of metal material processing application, in particular to a method for setting a shearing blade gap of a plate shearing machine according to the strength and the thickness of a sheared steel plate to improve shearing quality during blanking and shearing of a hot rolled steel plate.
Background
With the development of the economic society and the progress of the scientific technology, people deepen the concept of resource development and conservation, improve the utilization rate of various materials in production and manufacturing, and advocate a green and environment-friendly sustainable life style to be deep in mind. The method relates to the processing and application of a large number of hot rolled steel plates in the field of industrial manufacturing, and with the advance of a lightweight technology, the strength of newly developed steel materials is higher and higher, blanking and shearing before steel plate forming processing are more and more difficult, the shearing mode and the shearing surface quality directly influence the final utilization rate of the materials, the service life of manufactured parts, and the key point of whether advanced materials really exert the advantages of the advanced materials.
The traditional method for shearing the blanking of the hot rolled steel plate is mechanical shearing of a plate shearing machine, and the method has the advantages of convenience, rapidness, high production efficiency, low energy consumption, no pollution, complete industrial foundation, rapidness in popularization and the like, and is more suitable for popularization in the field of large-scale hot rolled steel plate processing. The improvement on the operation mode and the specification of the plate shearing machine can meet the requirement of blanking and shearing of steel materials in the industrial manufacturing field, in particular to high-strength thick hot-rolled steel products.
In recent years, novel blanking methods such as laser cutting, plasma cutting and water cutting are also provided in the processing mode, and the method is greatly beneficial to improving the quality of the blanking shearing surface of the hot-rolled steel plate, but the methods have the common defects that the cost is too high, the energy consumption is high, the efficiency is low, the application place is limited, and the like, and cannot be popularized.
The manufacturing process of the steel part is a production flow with multiple and complex processes, and the process flow can be simply divided into two types, namely a forming process and a blanking separation process. The forming process refers to a process of changing the shape and structure of the steel material by using the ductility of the steel material and the action of external force, such as flanging, bending, stamping and the like. The blanking and separating process is to remove redundant materials and provide plates with accurate size for the forming process, such as shearing, blanking, grinding, edge planing and the like.
Disclosure of Invention
In order to improve the material utilization rate and avoid the influence on the material strength and the service life due to separation, the invention provides the blanking and shearing method of the hot rolled steel plate, which is accurate in shearing, blanking, grinding and edge planing.
The technical scheme of the invention is as follows: a blanking and shearing method for a hot-rolled steel plate is characterized in that the tensile strength of the hot-rolled steel plate is 260-1200MPa, and the thickness of the hot-rolled steel plate is 0.7-20.0 mm; the method is characterized in that the shearing sequence comprises a fillet area, a bright area, a fracture area and burrs;
according to industry habits and experiences, the hot rolled steel plates are divided into 4 strength grades, and each strength grade is divided into 4-6 thickness grades according to specifications for research. And then, performing a comparison test on each hot rolled plate with a specific strength grade and thickness grade by adopting a variable shearing machine gap, analyzing and comparing, and preferably selecting an optimal gap value.
Evaluating the quality of the shearing surface according to the proportion of a fillet area, a bright area, a fracture area and burrs on the shearing surface and the surface flatness; the shear surface quality is evaluated by means of detection equipment, a microscope is usually used for observing the microscopic morphology and microstructure, and the shear gap setting reasonableness is evaluated by measuring the change of mechanical properties by a stretching instrument.
1. Examples of visual methods include:
the shearing section forms four characteristic areas of a fillet area, a bright area, a fracture area and burrs according to the sequence of the shearing process.
The fillet area is also called as a collapsed angle, and the fillet area is an area which is formed by the sheet metal being extruded by the shear blade to force the internal structure of the metal to flow and is easy to form a certain fillet and is called as a fillet area. The fillet area has no obvious influence on the processing and forming, but the deformation degree and the deformation size influence the appearance shape and the dimensional accuracy of the shearing surface.
The bright area is an area with a smooth and flat surface formed by the sheet material extruded in the horizontal direction of the shearing edge. The bright areas are called because the surface is smooth and bright. The part is the most flat part in the whole shearing surface and the part with the optimal surface quality, so the proportion of the bright area in the whole shearing surface is increased as much as possible in the shearing process, and the forming is facilitated.
The rupture zone is also known as the fracture zone: the fracture zone is formed after the upper and lower shear blades meet in crack propagation, is caused by crack propagation and fracture, is called as a fracture zone, has a rough surface and is not beneficial to forming, the proportion of the fracture zone in the whole shearing surface is reduced as much as possible in shearing, and cracking of parts caused by the fracture zone in forming is avoided.
The burrs are not formed at the contact position of the plate and the shear blade but formed at a certain distance in the advancing direction of the shear blade, the cracks grow continuously under the action of external force, and a bulge with a certain thickness is formed when the plate is completely broken. It is also not conducive to subsequent formation of material and should minimize the formation of burrs.
In a word, the proportion of the four characteristic areas in the whole shearing surface is observed by naked eyes through a visual inspection method, the larger the proportion of the bright area is, the better the shearing quality is, the forming is favorable, and on the contrary, the larger the proportion of the fracture area and the burr area is, the worse the shearing quality is, the forming is not favorable.
2. Examples of quantitative assays are:
the influence of the shear gap on the crack sensitivity of the hot rolled steel sheet was investigated by setting the test time gap at 2% t, 5% t, 6.6% t, 10% t, and 15% t for a steel sheet of a certain strength and thickness (the tensile strength Rm of the test piece of this time is 745MPa, and the thickness t is 5.0 mm). The rules are quantitatively studied from the changes in morphology, texture, shear-tensile properties.
(1) Influence of gap on shear morphology
The width of the bright zone increases significantly with increasing shear gap, while the shear plane area also increases. The increase in the shearing area is caused by the generation of burrs. An increase in the bright area is also seen, indicating that the bright area of the steel plate increases with increasing gap in the range of 2% t-15% of the gap. In addition, it was found that the burr rapidly grows up when the gap is 10% t or more, which means that the shearing quality is deteriorated due to an excessively large gap, and therefore, the gap of the steel sheet should be controlled within 10% t.
(2) Influence of gap on shear plane texture
And respectively observing the organization characteristics of the fillet area, the bright area and the fracture area under different clearance conditions by using a scanning electron microscope. Three shearing conditions of 2% t, 6.6% t and 15% t are respectively selected for observation.
The organization of the fillet area under the three gaps of 2% t, 6.6% t and 15% t is found that a small amount of micro-holes are generated in the fillet area. Comparing the microstructure images of the bright area and the fractured area under different gaps, the micro-holes are generated under 3 gap conditions, but the smaller the gap is, the smaller the number and the size of the micro-holes are. This indicates that the smaller the gap is, the less the crack origin is, and the better the formability is, in the range of 2% t to 15% t.
(3) Effect of gap on tensile Properties in shear
In order to examine the influence rule of the shearing surfaces obtained under the different clearance conditions of 2% t, 5% t, 6.6% t, 10% t and 15% t on the tensile property of the material, the size of the tensile sample is designed into a half-pulling sample. The straight edge is also the object to be studied when processing, and other edges are processed by linear cutting and polished to eliminate the influence of cutting on the sample.
The shear quality was evaluated using the load-displacement curve of the tensile test, and for comparison, a sample of type 6 was also introduced, which was also ground after linear cutting, and was regarded as a standard sample completely free of 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. It was again demonstrated that the steel sheet shear gap should be controlled within the range of 10% t, and that the shear gap is 2% t as best for the strength and thickness of the steel sheet tested this time.
From the above experimental comparison, the following conclusions can be drawn: the blanking and shearing method for the hot rolled steel plate is characterized in that when the mechanical shearing edge clearance of the hot rolled steel plate with the strength of 260-.
The material utilization rate (part qualification rate) of the invention is improved by 15 percent; 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 electric energy is averagely saved by 25 yuan/ton.
The strength and the thickness of the hot-rolled steel plate are measured before shearing, the measurement results of not less than three different positions are averaged, and the material of the cutting edge of the plate shearing machine is selected and the cutting edge clearance is set according to the measurement results of the strength and the thickness.
Detailed Description
The following examples are given to illustrate specific embodiments of the present invention, but the present invention is not limited to the following examples.
Example one
I object confirmation
The hot-rolled carbon structural steel Q235B is of a product thickness specification of 3.0mm, and the strength and the thickness of a sheared object are measured and verified before shearing (the strength can be simply converted and calculated by measuring the hardness). The measurement result was tensile strength of 475MPa and thickness of 2.97 mm. If the steel plate is a whole steel plate, the strength and thickness values marked on the quality guarantee certificate attached to the steel plate when the steel plate leaves a factory can be referred, and repeated measurement is not needed.
II plate shearing machine parameter setting
According to the strength value 475MPa and the thickness value 2.97mm of the steel plate measured in the previous step, the corresponding strength and thickness in the shear blade gap reference table of the plate shearing machine in the comparison table 1 correspond to the line 5 of the serial number, the reference value of the shear blade gap is 1.0 t-1.2% t, and the gap is set to be 0.03 mm.
III Fine tuning determination
Starting the plate shearing machine to perform trial shearing, observing the proportion of a bright area of a shearing section in the total section, and observing whether burrs exist, wherein if the proportion of the bright area is more than 20% and no obvious burrs exist, the shearing is performed without adjustment; if the proportion of the bright area is less than 20 percent, or obvious burrs exist to finely adjust the clearance of the shearing edge in a small direction, repeating the steps until the proper proportion is achieved.
Example two
I object confirmation
The hot-rolled low-alloy structural steel Q460C is of a product thickness specification of 10.0mm, and the strength and the thickness of a sheared object are measured and verified before shearing (the strength can be simply converted and calculated by measuring the hardness). The measurement result was 650MPa in tensile strength and 9.95mm in thickness. If the steel plate is a whole steel plate, the strength and thickness values marked on the quality guarantee certificate attached to the factory can be referred to, and repeated measurement is not needed.
II plate shearing machine parameter setting
According to the strength value 650MPa and the thickness value 9.95mm of the steel plate measured in the previous step, the corresponding strength and thickness in the comparison table 1 correspond to the line 7 with the serial number, the reference value of the blade gap is 1.4 t-2.5% t, and the gap is set to be 0.20 mm.
III Fine tuning determination
Starting the plate shearing machine to perform trial shearing, observing the proportion of a bright area of a shearing section in the total section, and if the proportion of the bright area is more than 20% and no obvious burr exists, shearing without adjustment; if the proportion of the bright area is less than 20 percent, or obvious burrs exist to finely adjust the clearance of the shearing edge in a small direction, the steps are repeated until the proper proportion is reached.
TABLE 1 shear blade gap reference table for plate shearing machine
Note: in the table, Rm represents the tensile strength of the steel sheet, and t represents the thickness of the steel sheet.
Claims (5)
1. A blanking shearing method for a hot rolled steel plate is characterized in that the tensile strength of the steel plate is 260-1200MPa, and the thickness t of the steel plate is 0.7-20.0 mm; it is characterized in that the clearance between the cutting edges is 1.0-6.0% t.
2. The method for shearing a hot rolled steel sheet as claimed in claim 1, wherein Rm is 260-330, Rm represents the tensile strength of the steel sheet and has a unit of MPa; selecting any one of the following:
(1) t is more than or equal to 0.7 and less than or equal to 3.0, and the clearance between the shear blades is 1.0 to 1.5 percent t;
(2) t is more than 3.0 and less than or equal to 12.7, and the clearance between the shear blades is 1.5 to 2.5 percent t;
(3) t is more than 12.7 and less than or equal to 16.5, and the clearance between the shear blades is 2.5-3.5% t;
(4) t is more than 16.5 and less than or equal to 20.0, and the clearance between the shear blades is 4.5 to 6.0 percent t; t is the thickness of the steel sheet in mm.
3. The blanking and shearing method for hot rolled steel plate according to claim 1, characterized in that 330< Rm ≦ 700, Rm represents the tensile strength of the steel plate in MPa; selecting any one of the following:
（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) t is more than 16.5 and less than or equal to 20.0, and t is 3.0-5.0 percent; t is the thickness of the steel sheet in mm.
4. The blanking and shearing method for hot rolled steel plate according to claim 1, characterized in that 700< Rm < 1000, Rm represents the tensile strength of the steel plate and has the unit of MPa; selecting any one of the following:
（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) t is more than 17.0 and less than or equal to 20.0, and t is 3.5-4.5 percent; t is the thickness of the steel sheet in mm.
5. The blanking shearing method of hot rolled steel plate as claimed in claim 1, wherein 1000< Rm < 1200, Rm represents the tensile strength of the steel plate and has the unit of MPa; selecting any one of the following:
（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) t is more than 17.0 and less than or equal to 20.0; 3.2-4.0% t; t is the thickness of the steel sheet in mm.
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| CN2785771Y (en) * | 2005-02-02 | 2006-06-07 | 金荣范 | Circular shear blade for circular shears |
| JP2007021663A (en) * | 2005-07-19 | 2007-02-01 | Jfe Steel Kk | Shearing crack preventing method for steel plate |
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| CN2785771Y (en) * | 2005-02-02 | 2006-06-07 | 金荣范 | Circular shear blade for circular shears |
| JP2007021663A (en) * | 2005-07-19 | 2007-02-01 | Jfe Steel Kk | Shearing crack preventing method for steel plate |
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