Collect
Check out my collection
0
Useful +1
Thick plate
Steel plate of 20.0-60.0mm thickness
China's national standard GB/T 15574-2016 "Steel Product Classification" national standard will be broadly divided into thin plate (less than 3mm) and thick plate (not less than 3mm)
[1]
.
In scientific research and production, China divides strip steel into five categories according to thickness: extremely thin strip, thin plate, medium plate, thick plate and extra thick plate. In China, the steel plate with a thickness below 0.2mm is called an extremely thin strip, the steel plate with a thickness of 0.2-3mm is called a sheet, the steel plate with a thickness of 3-20mm is called a medium plate, and the steel plate with a thickness of 20-60mm is called a thick plate
[2]
The steel plate with a thickness of more than 60mm is called an extra-thick plate.
- Chinese name
- Thick plate
- Foreign name
- Thick plate
- exegesis
- Refers to the thickness of 20.0-60.0mm Steel plates
- Middle plate
- Thickness of 3-20.0mm
- Extra-thick plate
- More than 60.0mm
- use
- Construction engineering, machinery manufacturing, container manufacturing
Widely used in the manufacture of various containers,
Furnace shell
,
Furnace plate
Bridge and automobile static steel plate,
Low alloy steel
Steel plate, bridge steel plate, manufacturing steel plate,
Boiler plate
,
Pressure vessel
Steel plates,
Patterned steel plate
Automobile girder steel plate. Tractor parts and welding components.
Bridge steel plate: Used for large railway Bridges. Claim to bear
Live load
Shock, shock, corrosion resistance, etc.
Shipbuilding steel plate
: Used in the manufacture of Marine and inland ship hulls. High strength, plasticity, toughness,
Cold bending property
Good welding performance and corrosion resistance.
Boiler steel plate
Boiler plate
) : Used to manufacture a variety of boilers and important accessories, because the boiler steel plate in the middle temperature (350°C below) under high pressure working, in addition to withstand high pressure, but also by impact, fatigue load and water and gas corrosion, require to ensure a certain strength, but also have good welding and cold bending performance
[3]
.
In the world energy, resources are increasingly tight, sustainable development has become a consensus of the new situation, car weight reduction by people's attention. The appearance of laser Welding plate (TWB, Tailor Welding Blank), welding plates of different thickness and different properties together, for the weight reduction of automobile body stamping plate parts, has achieved good results, and has been large-scale industrial applications at home and abroad. However, there are the following problems with laser-welded plates.
A. a series of processes such as cutting and welding are increased, thus increasing production costs.
b. There is one (or several) more welds, which affects the surface quality, performance uniformity and appearance of stamped parts.
c. The sudden change of thickness can only be achieved at the weld, and the transitional connection between thick plate and thin plate cannot be achieved.
In order to solve these problems, a kind of variable thickness plate produced by rolling method has appeared abroad, called TRB plate (TailorRolled Blank). Obviously this name is affected by TWB, compared with the two, laser welding plate TWB does have the process of cutting and splicing, the English Tailor is both image and appropriate, but the rolling method of variable thickness plate and English Tailor common meaning is far away, the author suggests that the Chinese "rolled thick plate" referred to as "thick plate", the corresponding English TRB can still be used. Rolled thick plate has the following obvious advantages over laser welded plate.
A. Eliminate welding and a series of related processes, can reduce production costs, reduce energy consumption and process loss.
b. In continuous production, it has high production efficiency, easy operation and good reliability.
c. There is no weld, its surface quality is good, the uniformity of organizational properties is good, and the connection strength is greatly improved.
d. can easily obtain different thicknesses, easy to produce more than 2 kinds of thickness combination sheet.
e. The length and shape of the thickness transition zone can be controlled, and the transition curve can be designed according to the stress condition of the stamping part when it is in service.
Thick plate TRB can not completely replace TWB, the reason is that rolling thick plate also has its limitations, such as can not be the composition and performance of different, different width of the plate together, can not achieve curve splicing, three-dimensional splicing and widening splicing. The development trend is to replace the same width, the same material and the different thickness of the laser welded plate with rolled thick plate. The future development trend is to develop the next generation of thick plate in the transition zone according to the load and structural requirements that the laser welded plate cannot do
[4]
.
It is uneconomical to obtain differential thick plate by rolling single sheet in industrial production, and the economical, effective and practical method is to first roll out Periodic LongitudeProfile Strip (PLP strip for short), and then cut off the thick plate with growth degree L in sections.
PLP strips can be rolled in cold mills with front and rear winders. During the rolling process, a hydraulic cylinder installed in the mill yard is used to dynamically press down the strip with varying thickness according to the set program. The length of different thickness sections and the shape and size of the transition zone are guaranteed by the reasonable matching of the horizontal rolling speed and the vertical rolling speed. The thickness of the rolled piece is measured by the thickness gauge installed between the rolling mill and the winder, and the target thickness of the rolled piece is automatically controlled according to the deviation between the measured value and the set value to ensure the thickness accuracy.
The rolling process is carried out periodically and continuously until a roll of strip is completed and PLP strip is produced. The coiled PLP strip is annealed (or not) according to the requirements of the subsequent forming process, and the non-annealed strip is transferred directly to the rear processing unit for subsequent processing. First through the uncoiler uncoiling machine; Then straightening machine straightening; The TRB board is cut precisely to the determined size. Gather the cut sheets together as
Automobile stamping parts
Of the blank. TRB sheet material is mainly steel, can also be aluminum alloy or other
Metallic material
.
Compared with the traditional rolling technology, the industrial application of this new method has distinct characteristics and considerable difficulty. First of all, the rolling in the transition zone can be divided into downwards rolling and upwards rolling. The bite Angle, contact arc length, neutral Angle, front/back slip and rolling pressure distribution are different from those of traditional rolling, so new theories and formulas need to be established. Secondly, it is very difficult to achieve high-precision thickness control under the condition of frequent periodic thickness changes. Traditional automatic thickness control methods such as head locking AGC and pressure AGC cannot be simply applied, and new thickness control technologies need to be developed. In addition, for the rolling in the transition zone, even if the roll rotation is unchanged, due to the change of the rolled section and the role of front/back sliding, the rolled speed and tension at the entrance and exit of the deformation zone will also have a great periodic change, these factors will inevitably have an adverse impact on the shape and size accuracy of the rolled part and the process control, and need to be studied in depth
[5]
.
The transition zone of thick steel plate plays an important role in the rolling process and the use of products. The curve shape and size of the transition zone not only determine the overall and local bearing capacity of the stamping part, but also affect the stamping production and die design, and are closely related to the control level of the rolling process, so the optimal design of the curve of the transition zone of the differential thickness steel plate has important practical significance.
Select the transition curve to consider rolling, stamping, product service conditions and other factors, the size is long and the change of uniform and slow transition zone, is conducive to uniform bearing and stamping forming, the surface of the steel plate can hardly see the thickness of the traces of change. TWB plate is difficult to be used as the exterior plate of a car, and the thick plate with optimized transition curve provides the possibility for the production of the exterior plate of a car because it has no weld, the thickness transition is uniform and gentle, and the surface does not leave defects, which is another aspect of the thick plate is better than the TWB plate. The transition zone with shorter size and drastic thickness changes can save more metal, which is suitable for the occasion when the load changes sharply in the product service, the transition zone is too short, the difficulty of rolling and stamping is increased, and the thickness of the thick plate can not change suddenly like the TWB plate, and the minimum limit of the length of the transition zone is related to the roll diameter.
The selection of length, type and parameter design of transition curve will affect the production, forming and performance of thick plate, so it is necessary to carry out research in the following aspects.
a. The limit value of the shortest transition zone is formed under the conditions of the specified roll size, reduction speed and horizontal speed.
b. Optimized design of the type and size of the transition zone under the determined service conditions and stamping conditions of the finished product.
c. The rolling method of various transition curves and the change rule of matching the reduction speed with the horizontal speed are obtained
[3]
.
The rolling test of thick plate was carried out on the four-high cold rolling test mill of the State Key Laboratory of Rolling Technology and Continuous Rolling Automation of Northeastern University. The main test parameters are as follows: the diameter of the rolling roll is 105mm; Supporting roller diameter 300 mm; Roll surface width 300 mm; Rolling force (Max.) 4000kN. The rolled parts are made of low carbon steel. Rolled parts thick area 2.0-2.5mm, thin area 1.0-1.5mm, transition zone length 30-100mm. The formability test of the differential thick plate sample was carried out by the material forming tester. The test values of the cup process in the thick zone, thin zone and transition zone of the thick plate were not different, and the formability was good.
After the technology of producing thick plate by rolling method appeared, it was quickly applied in foreign countries. German Mubea company reported that it has produced more than 15 million pieces of thick plate supply to Audi, BMW, Volkswagen and other automobile manufacturers, and is widely used in making various beam, column, plate and tube parts of car body.
Rolled thick plate for automotive designers to add a better than laser welding plate lightweight material selection scheme, so that designers can choose different thickness, different length combination and different transition zone shape and size of thick plate according to the load of automotive parts and structural requirements, in order to obtain the best automotive weight reduction effect. This requires car designers to work closely with the developers and production plants of the differential plate, cooperate in the early stage of new model development, jointly analyze and solve the problems in the design and production of the thick plate, and make the advantages of the thick plate fully play
[4]
.
1. Rolled thick plate is superior to laser welding plate in connection quality, surface condition, performance uniformity and production cost, and can be used for weight reduction materials of the same material, equal width and variable thickness automotive plate, and has good application prospects.
2. Periodic variable thickness rolling is an effective method to produce thick plate with high efficiency and low cost. Northeastern University has already rolled thick plate samples with thickness ratio of 1∶2 on the experimental mill, and the test shows that its formability is good, and the core technology of rolling thick plate has been preliminarily mastered.
3. The appearance of rolled thick plate provides a new material for the designer to reduce the weight of the car, and the wide use of thick plate in the new model will receive the best effect of saving materials, reducing the weight of the car and reducing fuel consumption. This requires car designers to work closely with slab developers and production plants to advance together
[5]
.
