JPS6137020B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a rough shaped steel piece, which is a rolled material for shaped steel, by forging.

BACKGROUND ART Conventionally, rough shaped steel slabs used as rolling materials for shaped steel have been manufactured mainly by a blooming process, although some of them have been manufactured by a continuous casting process.

However, the blooming process is more efficient and yield efficient than the process of continuously casting molten steel to obtain slabs.
Since it is inferior in terms of energy consumption, etc., there is a tendency, especially in Japan, to gradually convert the process to obtaining steel billets by continuous casting.

BACKGROUND ART One of the processes for producing rough-shaped steel slabs for section steel based on the premise of continuous casting is to obtain rough-shaped steel slabs by continuous casting.

In the process of obtaining rough-shaped steel slabs by continuous casting, molds must be replaced for various cross-sectional shapes and sizes, which not only reduces equipment operation rate and productivity, but also requires complicated casting. Since the cross-sectional shape is continuously cast, there are quality problems such as cracks and segregation occurring during the cooling process of the slab.

In order to carry out continuous casting under high quality and productivity standards, it is necessary to reduce the number of slabs with rectangular cross sections as flat as possible, or in other words, to make one size lot as large as possible.

Therefore, it is necessary to obtain slabs with a rectangular cross section through continuous casting, and to convert these slabs into rough shaped steel slabs with various cross-sectional sizes in subsequent steps.

On the other hand, as in the conventional process of manufacturing rough-shaped steel slabs using a blooming mill, the process of obtaining rough-shaped steel slabs from a material with a rectangular cross section is a process in which rough-shaped steel slabs are produced using a pair of horizontal rolls with grooves. In the process of obtaining this, a rectangular large cross-section material must be used as the starting material in order to ensure the width of the flange portion of the rough shaped steel billet, which inevitably increases the number of passes and reduces productivity.

A proposal to apply a universal rolling mill to the process of obtaining rough-shaped steel pieces from square-section material
93851), and although the number of passes is significantly reduced compared to the groove rolling method, in the process of obtaining a rough shaped steel piece by rolling, due to the metal flow in the rolling direction, the number of passes is also reduced from the flange part in the rolling direction. As a result of the replenishment of metal flow, the flange is rubbed down, so it is essentially difficult to ensure the flange width of the rough shaped steel piece.

This invention was made with the object of obtaining a forming method that does not involve any rubbing down of the flange portion when obtaining a rough shaped steel plate from a material having a rectangular cross section.

The inventors have already proposed a technique for obtaining a rough-shaped steel piece from a rectangular cross-section material by forging as a forming method that does not involve any rubbing down of the flange portion (Japanese Patent Application No. 40280/1983).

The present invention relates to an improvement of the above-mentioned technology, and is characterized by repeatedly performing a forging compression process using a forging tool in the longitudinal direction of a metal material having a rectangular cross section, so that substantially the central portion in the width direction is In a method for manufacturing a rough-shaped steel piece forming a recessed part, a forging tool is provided with a forging tool at its longitudinal tip such that the reduction amount gradually decreases in one or both of the compression direction and the width direction compared to the steady rear part of the tool. When using a forging tool having a steady part and proceeding with the forging compression process, the part compressed in the unsteady part during the previous forging compression operation is compressed in the steady part during the next forging compression operation,
The present invention provides a method for manufacturing a rough-shaped steel piece in which a uniform cross-section of the rough-shaped steel piece is formed in the longitudinal direction of the material by repeating this process.

The forging machine in the present invention can be installed in a continuous casting line, in a blooming rolling line, or upstream of a section rolling line.

The present invention will be explained in detail below.

In general, forging is known to produce metal more easily in the width direction of the material than in the longitudinal direction, compared to rolling, and is extremely suitable for obtaining a desired cross-sectional shape.

However, forging is a process in which plastic working is applied to a material discretely, and is inferior in terms of productivity and efficiency to a process such as rolling, in which plastic working is applied continuously to a material.

However, for example, when forging cut slabs on a line where material moves at extremely low speeds (0.5 to 3 m/min), such as in continuous steel casting, or when the material speed at the subsequent stage, such as in the entry section of a rolling line, In contrast, in cases where low productivity and low efficiency compared to rolling do not become obvious problems, such as when the mass flow rate is balanced even when processed at extremely low speeds, it is possible to It is possible to take full advantage of the advantages of almost no metal flow and a large degree of freedom in changing the cross-sectional shape of the material.

Therefore, the inventors made a proposal (patent application
In the technique disclosed in No. 53-40280), a rough shaped steel piece as shown in FIG. 1 is obtained by a forging process as shown in FIGS. 2a and 2b.

That is, as shown in FIG. 2a, the forging tool 1 is set at the center of the material 2 (bloom in this example),
By compressing the material by a predetermined amount as shown in FIG. 2b, a rough shaped steel piece 2' corresponding to the shape of the forging tool can be obtained. The total width of the obtained rough slab can be adjusted depending on the tool shape and the amount of forging.
Due to the characteristics of forging, the flange width of the rough-shaped steel slab does not become smaller than the thickness of the starting square cross-section material, and there are almost no cropped parts, resulting in a well-shaped rough-shaped steel slab with an extremely high yield. is obtained.

FIGS. 3a and 3b show a case in which a rough-shaped steel piece is manufactured from a slab by forging by simultaneously performing compression in the vertical and horizontal directions. A vertical tool 3 and a horizontal tool 4 are set at predetermined positions on the slab 5, and compression is performed simultaneously with the tools 3 and 4 until the desired dimension is achieved. In this case, the forging load is increased compared to the method shown in FIG. 1, but the flange height of the rough shaped steel piece 5' is characterized by being significantly larger than the thickness of the slab 5. Therefore, it is an extremely effective method when manufacturing a rough shaped steel billet whose flange height is higher than the thickness of the steel billet.

FIGS. 4a and 4b show an example in which a rough-shaped steel piece is manufactured by forging from a slab by first performing vertical compression and then horizontal compression. First, the tool 3 is set at the center of the slab to compress the slab by a predetermined amount in the vertical direction, and then the tool 4 is used to compress the slab horizontally to a predetermined width. It may be compressed with the tool 4 while being held in that position or after being returned to the position before compression. By adopting such a method, the forging load is reduced compared to the case shown in FIG. 3, and almost the same effect can be obtained.

Figures 5a and b show the case where a horizontal tool is held in a position where the full width of the predetermined rough-shaped steel billet can be obtained, and a vertical tool is used to perform vertical compression to produce a rough-shaped billet. This is an example. By forging and compressing the steel piece 8 in the vertical direction with the tool 6, the steel billet 8 expands in the horizontal direction, but the tool 7 prevents this width expansion. Therefore, although the rough shaped steel piece 8' extends slightly in the longitudinal direction, the flange width becomes larger than the thickness of the steel piece 8, and the same effect as in the case of FIGS. 3 and 4 can be obtained. However, the main purpose of this method is to prevent the rough shaped steel piece 8' from widening by using the tool 7.
It is suitable for forging with a relatively small width expansion. Further, since the tool 7 does not perform compression, it may be a manipulator used for rolling, for example.

By the above-mentioned method, a rough-shaped steel slab is manufactured from a rectangular cross-section material, but the length of the steel slab is usually
The length is around 10m, and compression molding this length of steel piece at once would require a huge forging machine, which is impractical.

Practically speaking, the length of the steel billet is divided into several steps and the forging and compression process is repeated in sequence.

FIGS. 6a, b, c, and d schematically show the process of the repeated forging and compression process. First, as shown in (a), forging compression is started using the tool 9 from one end of the steel piece 10, and the first stage of compression is completed with the tool 9 in the state shown in (b). Next, insert the tool 9 or the steel piece 10 (c)
The second stage of compression is performed by moving it to the position shown in . In that case, in order to prevent the occurrence of defects and shape defects at the boundary, the tool 9 is overlapped with the already forged part by a distance m as shown in (c), and the second stage of compression is performed as shown in (d). . By repeating the forging and compression process sequentially in the longitudinal direction of the steel piece using this method, a rough-shaped steel piece with a good shape can be obtained without generating flaws.

The forging machine used to perform the forging compression described above is not a special forging machine, but a commonly used type forging machine, and there is no problem at all.

Figures 7a, b, c, and d show the rough shape of the bloom when it is compressed only in the vertical direction using the forging tool that has a uniform shape in the length direction without unsteadiness as explained so far. This figure shows an example of the shape of a steel piece. When performing length step forging, the constraint state of the material itself is different between the forged part and the unforged part, so the width expansion near the forging boundary is different, and (a),
As shown in (b) and (c), the inside of the flange becomes stepped, causing flaws and at the same time large longitudinal variations in flange thickness and flange width. Therefore, the shape near the boundary portion and the shape of the steady portion are different, which is undesirable in terms of rolling. In addition, since there is no unsteady part in the tool for the web, the amount of reduction in each part is the same, and as a result, as shown in (d), the metal is stretched down in the vertical direction at the boundary part, resulting in step-like flaws. This is unfavorable for rolling.

The present invention solves the above-mentioned problems and provides a means for obtaining a rough-shaped steel piece with good shape and no flaws or defective shape.

FIG. 8 shows a forging tool with a uniform cross-sectional shape in the longitudinal direction, which is composed of only stationary parts and is based on the technique proposed by the inventors mentioned above. When using the forging tool shown in this figure, the boundary between the forged portion and the unforged portion of the material after step forging is a stepped portion that stands vertically.
During the next step forging, this part flows to the flange side and the web side due to the forging of the unforged part, leaving a step on the inside of the flange and the web part, which should be uniform after the step forging is completed. .

FIG. 9a shows a forging tool applied in this invention. The forging tool shown in Fig. 9a has an unsteady portion at its longitudinal tip (in the range of distance n in the length direction) in which the amount of reduction gradually decreases in both the compression direction and the width direction. . By providing such an unsteady part, the boundary part in the material after forging becomes a smooth transition deformation part, and when the next step forging is performed, this boundary part is smoothly rolled down from the unforged part to the already forged part. As a result, the metal is prevented from being rubbed down, and there is almost no stepping after forging is completed.

FIGS. 9b and 9c show other embodiments of the above-mentioned unsteady portion.

What is shown in FIG. 9b is a forging tool that has an unsteady portion in the range of the longitudinal tip n in which the amount of reduction gradually decreases in the compression direction.

What is shown in FIG. 9c is a forging tool having an unsteady portion in the range of the tip n in the longitudinal direction such that the amount of reduction gradually decreases in the width direction.

What is shown in FIG. 9a can be said to be a forging tool having an unsteady part that is a composite of the unsteady parts shown in FIGS. 9b and 9c.

FIGS. 10a, b, and c show some cross-sectional shapes of the stationary part of the forging tool applied in the present invention. For example, when a large width expansion is required, that is, when trying to obtain a rough-shaped steel piece with a wide web width, a flat-shaped tool shown in FIG. 10a is used. In this way, a forging tool of an appropriate shape is used depending on the cross-sectional shape and dimensions of the desired rough-shaped steel piece. Next, examples will be described.

FIG. 11 specifically shows an example of a circular arc-shaped forging tool used when actually manufacturing a rough-shaped steel piece from a bloom by step forging. The total length of the tool is 1000 mm, the length of the unsteady part is 300 mm, the radius of the arc of the steady part is 120 mm, and the radius of the spherical surface of the unsteady part is 300 mm.
mm.

FIG. 12 shows the cross-sectional shape of the boundary portion of a rough shaped steel piece manufactured by step forging using the forging tool shown in FIG. 11. The dimensions of the bloom used as the material were 300H x 340W x 7500L, and the tool overlap at the boundary was 100mm, and step forging was performed 14 times. The forging machine used at this time had a maximum capacity of 1500 tons and a forging speed of 50 mm/sec. The forging amount is 200mm, the material temperature is about 1100℃ on average, and the forging load is about 700Ton per unit step.
The time required to complete the forging was approximately 150 seconds, and the product was able to be fully matched to the rolling pitch of the product factory. In this figure, the solid line is the tool with an unsteady part, and the dotted line is the cross-sectional shape of the rough shaped steel piece when forged with a conventional tool consisting only of a steady part. The forging flaws could be completely eliminated by using this tool. In addition, arc-shaped tools have a characteristic that the width of the material in the horizontal direction is smaller than that of flat tools, and are suitable for forging that does not require a large width increase. The crop length of the obtained rough-shaped steel slab is approximately 100 mm at both the leading and trailing ends, and this method is significantly more advantageous than blooming rolling in terms of yield.

FIGS. 13a and 13b show the absolute amounts of web height and flange thickness measured over the entire length of the rough shaped steel piece. In either case, the solid line represents the dimensions obtained by the tool according to the present invention, and the dotted line represents the dimensions obtained when forged using a conventional tool having a uniform cross-sectional shape in the longitudinal direction and consisting only of a stationary portion. At the web height, the tip and rear ends of the rough shaped steel piece are not constrained by the material itself, so no matter which tool is used, they will be slightly larger than the center, but the most notable feature is the dimensions of the boundary, i.e. With conventional tools, the difference in web height between the stationary part and the boundary part is about 15 mm, and unevenness occurs over the entire length, but with the tool of the present invention, the amount of unevenness is reduced to 2 to 3 mm, and the overall length is almost the same. A rough shaped steel piece with uniform and stable shape and dimensions is obtained.

Similar to the web height, the flange thickness has significant characteristics at the boundary. In the case of conventional tools, the amount of reduction is constant over the entire length of the tool, so
The amount of width expansion of the material differs due to the difference in the restraint effect of the material corresponding to the leading and trailing ends of the tool. As a result, a step of approximately 10 mm is created on the inside of the flange, which corresponds to the forging boundary. On the other hand, in the case of the tool according to the present invention, since the reduction amount is different at the tip and rear end of the tool, the amount of width expansion in the steady part and the boundary part of the material is almost equal,
The stepped amount is reduced to approximately 2 to 3 mm, and a good rough-shaped steel piece with uniform flange thickness over the entire length is obtained.

As is clear from the above, by performing step forging using the forging tool according to the present invention, the effect of improving the shape and dimensions of the rough-shaped steel piece is extremely large compared to the conventional method, and the desired rough-shaped steel piece can be obtained. A piece was obtained.

It should be noted that the present invention can be applied in various ways, and the one shown in this embodiment is just one example, and it goes without saying that all applications that meet the purpose of the present invention are included.

[Brief explanation of the drawing]

Figure 1 is a sketch showing a rough shaped steel piece, Figure 2a,
Fig. 3b shows the process of obtaining a rough-shaped steel billet by forging, and Figures 3a and b show the process of obtaining a rough-shaped steel billet from a slab by simultaneously performing compression with a forging tool in the vertical and horizontal directions. Figures 4a and 4b are diagrams showing the process of obtaining a rough shaped steel billet from a slab by first performing vertical compression and then horizontal compression, and Figure 5. Figures a and b are diagrams showing the process of obtaining a rough-shaped steel slab from a slab by vertically compressing the slab by positioning it in accordance with the width of the rough-shaped steel slab to be finally obtained; Fig. 6a , b, c, and d are diagrams schematically showing the repeated (step) forging compression process. A diagram showing the pattern of the stepped part that occurs when manufacturing a rough shaped steel piece from the raw material,
FIG. 8 is a perspective view of a forging tool having a uniform cross-sectional shape in the longitudinal direction; FIGS. Figures 10a, b, and c are diagrams showing some of the cross-sectional shapes of the stationary part of the forging tool in the method for manufacturing a rough-shaped steel billet according to the present invention, and Figure 11 is a diagram showing the cross-sectional shape of the stationary part of the forging tool shown in Figure 9a. FIG. 12 is a diagram showing the cross-sectional profile at each stage of the unsteady part. FIG. 12 is a diagram showing the difference in the cross section of the step forging boundary between the conventional tool and the tool of the present invention. FIGS. FIG. 3 is a diagram showing the unevenness of the web portion and flange portion of the rough-shaped steel billet after manufacturing the rough-shaped steel billet of the invention. 1...Forging tool, 2...Material, 3...Vertical tool,
4...Horizontal tool, 5...Slab, 6...Tool, 7...
Tool, 8... Steel piece, 9... Tool, 10... Steel piece.

Claims (1)

[Scope of Claims] 1. A method for manufacturing a rough-shaped steel billet in which a forging compression process using a forging tool is repeatedly performed in the longitudinal direction of a metal material having a rectangular cross section to form a concave portion substantially at the center in the width direction. The forging compression process is performed by using a forging tool that has an unsteady part at its longitudinal tip such that the reduction amount gradually decreases in one or both of the compression direction and the width direction compared to the rear steady part of the tool. When advancing, the part that was compressed in the unsteady part during the previous forging compression operation is compressed in the steady part during the next forging compression operation, and by repeatedly advancing this, a uniform cross section of the rough shaped steel piece is created in the longitudinal direction of the material. 1. A method for manufacturing a rough-shaped steel piece, characterized by forming a rough-shaped steel piece. 2. Claims characterized in that by compressing a steel billet simultaneously in the vertical and horizontal directions and sequentially repeating this forging compression process, a roughly shaped steel billet having a uniform cross-sectional shape in the longitudinal direction is obtained. 1st
A method for manufacturing a rough shaped steel billet by forging as described in Section 1. 3. Claim 1, characterized in that the forging compression step of first compressing the steel piece from either the vertical or horizontal direction, and then sequentially repeating the forging compression process from either the horizontal or vertical direction. A method for producing rough shaped steel billets by forging. 4 Hold either the vertical or horizontal forging tool in a position where the specified dimensions can be obtained, perform compression with either the horizontal or vertical forging tool, and compress the steel piece in the vertical or horizontal direction. 3. The method for manufacturing a rough-shaped steel billet according to claim 2, wherein the forging and compression step is sequentially repeated while preventing width expansion.