JPH0214121B2 - - Google Patents

Description

[Detailed description of the invention] (Object of the invention) H
A beam for H-shaped steel that prevents insufficient wall thickness (shrinkage) at the flange end when rough rolling intermediate rolled material in the form of a beam blank for shaped steel, and that has a relatively large web height from a narrow slab. The present invention provides a method for rough rolling a blank. (Prior art) Recently, a slab with a rectangular cross section is used as a raw material, and after the short side is widened by etching rolling, the long side is rolled to produce a roughly rolled material in the shape of a beam blank, and thereafter, H-beam steel is made by universal rolling. Manufacturing methods have come into widespread use. Figure 1 shows the rolling procedure of the rough rolling process, in which the short pieces 1a of the slab 1 are rolled into central protrusions 2a, 2.
Etching hole type group 21, 2 having b,...2n
Sequentially spread and roll at 2,2n to form a flange bulge.
After forming F ₁ to _{F 4} , flat web pressing part 3
Generally, a method was used in which a beam blank 1a of a predetermined size was rolled using a forming hole die 3 having flange forming holes 3b on both sides of the beam blank 1a (for example,
No. 19361). However, with this rolling method, the shaped hole type 3
In the process of rolling down the web part, the flange part is also elongated at the same time as the web elongates in the length direction of the rolled material, resulting in an excessive reduction in the cross section of the flange part, and the product dimensions after rough rolling and finish rolling. There was a problem that the shape did not reach a certain quality level. This state of reduced cross section is generally referred to as flange thinning, and is the second
As shown in the figure, there was a point where the flange width Wf' was shorter than the normal flange width Wf, and the flange corner C was not at a right angle. This tendency is often seen in products with large web heights and large flange widths, and in the past, in anticipation of the amount of flange wall shrinkage due to web reduction, sufficient flange bulges F ₁ to _{F 4} were created. In order to achieve this, the initial width of the slab was increased and a large amount of edging rolling was performed, which increased the time required for rough forming and hindered rolling efficiency. In addition, in order to apply materials with large slab widths, continuous casting equipment, rolling mills,
This method was constrained by equipment conditions such as rolling material conveyance lines or heating furnaces, and was forced to significantly reduce heating efficiency. As a means to solve these difficulties, for example, the technique disclosed in Japanese Patent Publication No. 58-37042 is well known. This technique involves splitting and rolling the side surface of a rectangular cross-section material corresponding to the flange in the same manner as described above, and then rolling the side surface corresponding to the flange of the material to be rolled using a hole mold that has deep grooves on both sides of the web pressing bulge that do not contact the flange of the material to be rolled. This is designed to generate a positive metal flow toward the flange. This conventional technology method can produce a wide flange H-section steel from a thin slab, and has the effect of reducing the number of passes and generating less clots. However, since the flange side surface is not constrained during rolling,
The guide mechanism for correctly guiding the center of the rolled material to the center of the pass line is complicated, and there is a problem that bending in the length direction tends to occur. The present invention solves the problems of the prior invention and provides a new rough rolling method for manufacturing H-section steel with a large web height from a narrow slab. (Structure and operation of the invention) FIG. 3A shows the relationship between the shaping roll pair 31 and the rolled material 1 for carrying out the method of the present invention,
The material to be rolled 1 has a shape after the final etching rolling has been completed in the etching hole shape 2n shown in FIG. 1 described above. That is, in the present invention, a rectangular cross-section steel piece 1
Sequentially expand the flange bulge using an edging hole mold.
The steps to form F ₁ to _{F 4} are according to well-known techniques, and detailed explanation will be omitted. The width W between the outer wall surfaces of the left and right flange forming holes 3b and 3b' of the shaping hole mold 31 used in the present invention is formed to be approximately equal to the web height of the rolled material at the end of the edging rolling. In the present invention, the width W between the holes is particularly referred to as the total width of the holes. Further, the hole width Wa is formed so as to have a sufficient gap Fc in accordance with the thickness Ft of the flange bulge of the material to be rolled, as shown in FIG. 3C. Note that the hole width Wa in the present invention is approximately 1/ of the depth h from the web pressing surface S of the shaping hole mold to the bottom of the hole mold.
The gap Fc between the side surface of the flange bulge of the material to be rolled and the side surface of the flange forming hole corresponding to this position is formed so that Fc/Wa>0.1. The conventional hole width Wa is the thickness of the flange bulge of the rolled material.
It is customary to set it smaller than or equal to Ft, and the point that the hole width Wa of the shaped hole type in the present invention has a relatively large gap with respect to the thickness of the flange bulge of the material to be rolled will be described below. It is distinctive along with the shape of the orthopedic web press. As shown in FIG. 4, the orthopedic hole-type Ubu pressing surface is formed into a gently curved surface with a central protrusion with respect to the center C in the width direction. The shape of the curved surface may be such that the web pressing surface is a part of an ellipse or a part of a circle, and both ends are machined with an appropriate radius R. The appropriate degree of the curved surface is such that the ratio h ₁ /Wb of the rising height h ₁ of both ends to the width Wb of the web trunk is 0.03 or more. In other words, if this ratio is less than 0.03, there is not much difference in the amount of metal flow toward the flange compared to the conventional flat shaped hole type. In addition, the upper limit of this ratio is set in accordance with the balance of the overall process capacity, such as the rolling capacity and sawing capacity of the universal mill in the next process, so that the amount of wall thickness at the base of the flange and web after shaping rolling does not become excessive. Should. By the way, generally the flange width F ₀ shown in FIG.
The flange width is obtained through the rough rolling process of dot bone shape, shaping rolling, universal rolling, and finishing rolling.
When manufacturing Fn H-section steel, the thickness of the flange decreases as the web is rolled down, and the rate of decrease can be expressed as an index called flange width reduction rate β as shown in Equation 1. β=Fo−Fn/To−Tn ………(1) However, Fo: Flange width of rough rolled material To; Web thickness of rough rolled material Fn; Flange width of product Tn; Web thickness of product In addition, conventional web pressing As a result of experiments, it has been confirmed that when shaping roll is carried out using a shaping roll with a flat surface, the flange width shrinkage ratio β has a strong correlation with the inner diameter U of the product web, as shown in FIG. 6a. Based on the above, the present inventor further researched the shaping rolling conditions to minimize the flange width reduction rate, and as described below, tried to increase the metal flow from the web to the flange as much as possible, and to improve the shaping hole type. We learned that the key point is to reduce the web contact surface. In other words, when the rough rolled material 1 shown in FIG. 7A is shape-rolled to form the intermediate rough finished material _1a shown in FIG. . SF ₁ = SF ₀ ×△M/(T ₀ /T ₁ )−△M/(U × T ₁ )……
...(2) However, T ₀ ; Web thickness of the roughly rolled material SF ₀ ; One side flange cross-sectional area of the roughly rolled material T ₁ ; Web steel U of the finishing material; Inner web method △M; Metal flow from the web to the flange No. 7 In Figures A and B, when the web thickness is reduced from T ₀ to T ₁ , the length of the rolled material tries to elongate from L ₀ to L ₁ , but the flange restrains this elongation, so the web is compressed and The flange undergoes tensile deformation and the cross-sectional area of the flange decreases. Therefore, the overall elongation length _L2 is determined by the balance between the compressive force of the web and the tensile force of the flange, and the metal flow from the web to the flange, and as shown in equation (2), the metal flow △M is The larger the inner web width U (web contact surface), the smaller the one-sided flange cross-sectional area SF ₁
This means that you can increase the size of the image. In other words, as a result of the above elucidation of the metal flow, the shaping hole mold used in the present invention increases the metal flow by forming the web pressing part into a gently curved surface with a central protrusion in the width direction, and as a result, the metal flow at the flange part is increased. I was able to minimize the loss of meat. In addition, by making the full width W of the shaping hole mold approximately equal to the web height of the rolled material after finishing the shaping, the outer surface of the flange of the rolled material is aligned with the outer wall surface of the shaping holes 3b and 3b' during shaping rolling. A state of contact is maintained at all times, and metal flow in the web height direction is restricted. Therefore, the metal flow from the web to the flange portion is concentrated, contributing to an increase in the flange thickness. (Example) FIG. 6b shows the flange width reduction rate β according to the present invention, and compared to the conventional method, the effect of reducing the flange width reduction rate by about 30% has been obtained. Table 1 compares the required slab widths of the method of the present invention and the conventional method (method using a web pressing surface flat shaping roll), and the product size is 700 mm in web height, 300 mm in flange width, 13 mm in web thickness, Two examples are shown: one with a flange thickness of 24 mm, one with a web height of 800 mm, a flange width of 300 mm, a web thickness of 14 mm, and a flange thickness of 26 mm. The thickness of the flange after the shaping rolling was increased by 13 to 15%, and as a result, the slab width was reduced by 120 mm, which is a remarkable effect of the present invention. 【table】

[Brief explanation of drawings]

Figure 1 is a schematic diagram showing the conventional rough rolling process, Figure 2 is an explanatory diagram showing flange wall shrinkage, Figure 3 A is an explanatory diagram of the shaping hole die used in the present invention, and Figure 3 B is the completion of shaping rolling. FIG. 3C is an enlarged explanatory view of the roll hole mold part of FIG. 3B, FIG. 4 is a diagram showing the shape of the web pressing of the shaping hole mold used in the present invention,
Fig. 5 is an explanatory diagram explaining the dimensions of each part of the roughly rolled material and the product, Fig. 6 is a graph showing the relationship between the internal method of the product web and the flange width shrinkage ratio, and Fig. 7 A and B are the metal flow of the flange cross section. FIG. 1... Slab, 21, 22, 2n... Edging hole mold group, 3... Shaped hole mold, 31... Shaped hole mold used in the method of the present invention, W... Hole mold full width, Wa... Hole width, h...Hole depth, Ft...Flange bulge thickness,
Fc... air gap.

Claims (1)

[Claims] 1. After forming a flange bulge by sequentially splitting short pieces of rectangular cross-sectional steel pieces using an edging hole die group, the web and flange portion are shaped and rolled using a shaping hole die that has flange forming holes on both sides of the web pressing portion.H
In the rough rolling method for section steel, the hole width of the flange forming hole is formed to be at least 10% larger than the thickness of the flange bulge after the end of etching of the rolled material,
In addition, the web part of the material to be rolled is pressed by the shaping hole mold in which the overall width of the hole mold is formed to be approximately equal to the height of the web after finishing the etching, and the web pressing part is formed into a gently curved surface with a central protrusion in the width direction. A rough rolling method for H-beam steel, which is characterized by rolling the H-section steel while repeatedly rolling it down to cause metal flow to the flange portion.