JPH0445242B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method of manufacturing a high-rigidity hot-rolled steel sheet having continuous protrusions. [Prior Art] Conventionally, as a means to improve the bending resistance and buckling resistance, that is, the rigidity, of steel plates used in structures as strength members, welding of reinforcing materials or increasing the plate thickness has been carried out. This method causes an increase in cost and weight due to the increase in processing steps. On the other hand, a steel plate with protrusions is a hot-rolled steel plate that is obtained by hot rolling and has protrusions on only one side, and has concrete inside to be used as anti-slip flooring or as foundation piles for buildings. Filled material for spiral steel pipes (Japanese Patent Application Laid-Open No. 60-37484)
It is manufactured as. However, the role of the protrusions on these steel plates is mainly to improve slip resistance and frictional force, and the protrusions have a height of 2 to 2.
It is small at 4 mm and is not suitable as a strength member for structures. In addition, the manufacturing method is to form protrusions by one pass of caliber rolling at the final stage of rolling, and even if caliber rolling is performed at the reduction amount determined by the equipment constraints of the rolling mill, protrusions with a height of 4 mm cannot be formed. Since it is molded, it is almost at its limit (Japanese Unexamined Patent Publication No. 60-37484). Therefore,
This method cannot produce a steel plate with a protrusion height of 4 mm or more. In addition, as a method for preventing irregularities between the rolls and the steel plate during multiple pass rolling to obtain even higher protrusions, a universal mill system (Japanese Patent Laid-Open Publication No. 115304/1982) consisting of horizontal rolls and vertical rolls has been proposed. ing. However, with this method, it is not possible to suppress uneven displacement when the steel plate is bitten. Furthermore, the body length of the horizontal roll must be less than the board width, and in order to accommodate various user-required board widths, it is necessary to prepare a large number of horizontal rolls, which increases manufacturing costs. Another method is to machine the protrusions from a smooth steel plate, but when obtaining high protrusions,
This is not an economical method as it produces a lot of cutting waste. [Problems to be Solved by the Invention] The present invention provides a method for manufacturing a modified cross-section steel plate that reduces the weight of the structure and eliminates operating energy. [Means for Solving the Problems] The gist of the present invention is to provide a rolling mill having a work roll calibrated into a trapezoidal shape with an oblique side having an inclination angle of 65° or more and 80° or less on the side where the protrusions are formed. The machine performs hot rolling multiple times, and as the number of rolling passes progresses, the amount of rolling reduction per pass decreases. The center and the widthwise center of the material to be rolled are aligned using a widthwise movable width aligning device placed on the front and rear surfaces of the rolling mill, so that the thickness of the non-protruding part is 12 mm or more and the protrusion height is 5.5 mm or more. This is a method for manufacturing a hot-rolled steel sheet with a modified cross section, which is characterized by rolling. The present invention will be explained below based on the drawings. Figure 1 shows an example of a mounting plate with protrusions. Protrusion 20
As shown in the figure, a plurality of pieces are formed in width B and pitch L, continuous in the length direction of the plate, and in the width direction of the plate. Thickness t ₁ of protrusion 20 and thickness t ₀ of non-protrusion 21
should be determined based on the weight reduction effect and rigidity that should be secured depending on the application, but as shown in Figure 2, by setting the plate thickness ratio t ₁ /t ₀ to 1.2 or more, it is possible to achieve a value of 1 to 1.5. % weight reduction. The vertical axis in Figure 2 is the weight reduction effect for a smooth plate with the same rigidity as the steel plate with protrusions = 1-
Indicates [Weight (protrusion)/Weight (smooth)]. As is clear from Figure 2, by increasing the plate thickness ratio, that is, by increasing the protrusion height to 5.5 mm or more,
The rigidity of the steel plate is dramatically improved, making it possible to significantly reduce weight and omit reinforcing materials. Next, a method for manufacturing a steel plate according to the present invention will be explained. Figure 3 shows a rolling facility for manufacturing steel plates with projections. 1 is an upper work roll for rolling, and 2 is a lower work roll. The work roll on the side where the protrusions are formed is subjected to caliber processing as shown in FIG. 4. Reference numeral 3 denotes an auxiliary roll which prevents the work roll from being bent during rolling. As shown in Fig. 3, there is only one rolling mill for forming protrusions, and therefore, the caliber shape of the work roll is also one type for each protrusion to be formed, but it can be used once or multiple times. By performing caliber rolling, protrusions with arbitrary heights are formed.
Reference numeral 4 indicates a width aligning device, and reference numeral 5 indicates a thick steel plate with an irregular cross section. According to research by the present inventors, the protrusion height obtained by caliber rolling depends on the caliber shape of the work roll. FIG. 5 shows the relationship between caliber shape and print rate. Here, the print rate is obtained by protrusion height/reduction amount. As shown in Fig. 5, if the trapezoidal shape is used and the angle of inclination of the oblique side is 65° or more and 80° or less, a printing rate of 80% or more can be obtained. From this point of view, the lower limit of this angle of inclination is set to 65° and the upper limit is set to 80°. It has also been found that the protrusion height obtained by multiple passes of caliber rolling is independent of the rolling reduction rate of each pass, and is influenced by the total rolling reduction amount. This shows that even if an arbitrary reduction history is followed, if the total amount of reduction finally obtained is the same, the same protrusion height can be obtained. That is, the object to control the protrusion height is only the plate thickness before caliber rolling and the final plate thickness. Now, when forming protrusions using caliber rolling, the rolling part tries to stretch in the rolling direction, but is constrained by the protrusions.
It cannot be stretched sufficiently, and compressive stress acts on the rolled part, causing rolling waves due to buckling. This phenomenon occurs more easily as the rolling reduction rate increases and as the plate thickness decreases. Therefore, as the plate thickness becomes thinner,
That is, by decreasing the rolling reduction ratio as the number of rolling passes progresses, deterioration of the rolled shape can be prevented. In protrusion forming in multiple passes, it is necessary to align the widthwise centers of the work rolls 1 and 2 with the widthwise center of the rolled material 5 so that the protrusions formed in the previous pass are not crushed in the next pass. Therefore, a width adjusting device 4 movable in the width direction is arranged on the front and rear surfaces of the rolling mill, and rolling is performed while adjusting the width for each pass. [Example] Fig. 6 shows the equipment layout for implementing the present invention. In order to facilitate rolling, the steel material heated in the heating furnace 10 is transferred to a rolling mill 1 incorporating smooth work rolls.
2, the sheet is rolled to a predetermined caliber rolling start plate thickness. Next, as the work roll 1 or 2 on which the protrusions are formed, a trapezoidal shape 11 is used as shown in FIG.
The steel plate 5 is sent to a rolling mill 13 incorporating a caliber roll that has been processed into a caliber roll, and subjected to caliber rolling a plurality of times in a plate width alignment device 4 while aligning the width, thereby obtaining a steel plate 5 with protrusions. Note that the board width alignment device 4 may be, for example, a side guide. The above equipment performs multiple reciprocating caliber rolling operations.

[Table] Table 1 shows the results. In addition, in the table ~ are the test results of investigating protrusion height with respect to caliber inclination angle using plasticine. Comparing the present invention example and the comparative example,
It can be seen that when the number of rolling steps is two, the inclination angle of the caliber is in the range of 65° to 80° and the protrusion height is 5.5 mm or more. In addition, the irregular cross-section thick steel plate of the present invention is applicable not only to the case where the projection 20 is provided on the upper surface, but also to the case where the thick steel plate has the protrusion 20 on the upper surface.
Even when the projections 20 are provided on both the lower surface and the upper and lower surfaces as shown in FIG. 2 and FIG. 7-3, the weight reduction effect,
The process-saving effect can be utilized, and it can be manufactured by the same method as the present invention. [Effect of the invention] By using the modified cross-section thick steel plate of the present invention,
Compared to using smooth steel plates, the structure can be made lighter, and operating energy can be saved. Furthermore, by saving steps during processing, it is possible to reduce construction costs. Furthermore, according to the method of manufacturing a thick plate with irregular cross section according to the present invention, (1) protrusions are also formed by caliber rolling, so there is no material loss compared to conventional cutting methods. (2) Since the protrusions are formed by multiple caliber rolling, there is no restriction on the height of the protrusions, and a reciprocating pass of rolling prevents a decrease in productivity. (3) Since caliber rolling is performed using one rolling mill, the manufacturing equipment is compact and the processing cost of caliber rolls is minimized. (4) By reducing the rolling reduction pattern during caliber rolling as the rolling passes progress, deterioration of the steel plate shape can be prevented, and a steel plate with a predetermined protrusion height can be obtained by simply controlling the total rolling reduction amount. It will be done. (5) By making the roll caliber shape trapezoidal and setting the angle of inclination of the oblique side to 65° or more and 80° or less, it becomes possible to perform caliber rolling with a high printing rate, that is, with high protrusion height forming efficiency. (6) Protrusions can be formed without crushing the protrusions formed in the previous pass by disposing width-adjusting devices movable in the width direction on the front and rear surfaces of a rolling mill incorporating caliber rolls. Furthermore, even for various required plate widths, only one caliber roll is required, which prevents an increase in manufacturing costs.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a thick steel plate with a modified cross section of the present invention, FIG. 2 is a graph of the weight reduction effect of a steel plate with projections on a smooth steel plate, and FIG. 3 is an explanatory diagram of the manufacturing process of a thick steel plate with a modified cross section of the present invention. Figure 4 is a side view of a caliber work roll processed into a trapezoidal shape, Figure 5 is a graph of print rate for caliber shapes,
FIG. 6 is an explanatory diagram of the implementation of the present invention, FIG. 7-1,
Reference numerals 2 and 3 are cross sections of a thick steel plate with a modified cross section, which has a plurality of protrusions in the plate width direction that are continuous in the plate length direction. 1... Upper work roll, 2... Lower work roll, 3... Auxiliary roll, 4... Width alignment device, 5...
...An irregular cross-section thick steel plate, 10...Heating furnace, 12...Rolling mill incorporating smooth rolls, 13...Rolling mill incorporating caliber processing rolls.

Claims (1)

[Claims] 1. On the side where the protrusions are to be formed, hot rolling is performed multiple times using a single rolling mill that has a work roll calibrated into a trapezoidal shape with an inclination angle of the hypotenuse of 65° or more and 80° or less. As the number of passes progresses, 1
The rolling reduction amount per pass is reduced, and before each pass rolling, the widthwise center of the caliber-processed rolling work roll and the widthwise center of the rolled material are aligned in the widthwise direction on the front and rear surfaces of the rolling mill. 1. A method for producing a hot-rolled steel sheet with an irregular cross section, characterized by rolling the sheet to a thickness of 12 mm or more at the non-protruding part and a height of 5.5 mm or more at the protruding part, using a width aligning device that is movable.