JPH0447291Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention relates to a ribbed steel pipe for use in building reinforcement materials, which is suitable for use in fields that require exceptional strength, such as building reinforcement materials.

[Conventional technology]

This type of steel pipe is usually made into a tubular shape by passing the steel strip through forming rolls in which flat rolls and curved rolls are arranged in series, and welding it to form it continuously, but the inner and outer surfaces of the pipe body are non-rough. is normal.

[Problem to be solved by the invention] By the way, ribs are also called strength bones and are reinforcing members attached to reinforce plate-like or thin parts.
Conventionally, from the viewpoint of reinforcement, there has been no such steel pipe in which ribs having a continuous metal structure in the protruding direction are integrally formed on the outer wall surface of the pipe as part of the pipe. Some pipe bodies with triangular protrusions arranged vertically on the circumference have been proposed (Utility Model No. 50-75227
No.), its manufacturing method has not been disclosed,
The protrusions are probably formed individually by cutting or welding, and the metal structure of the ribs is not formed continuously and integrally in the protruding direction by rolling. Furthermore, since the surface is in a triangular zigzag shape, it is significantly different from a normal pipe shape, and its uses are naturally limited.

In this regard, regarding iron pipes, there is one in which an iron plate is first bent into a corrugated shape, then this is curved into a tubular shape, and both ends are overlapped and wound together to create a tubular body with a corrugated cross section (13329 No.), this was not a reinforcing rib formed integrally and continuously as part of the pipe body, but merely a wavy, uneven cross section, and was a discontinuous iron pipe with both ends not welded. Moreover, in order to make a steel plate with a certain width into a corrugated shape, the surface area must be considerably increased in order to make a steel pipe with a predetermined diameter.As a result, the resulting steel pipe has the drawback of being extremely thin, and especially with exceptional strength. It was insufficient in terms of strength for applications such as building materials that require

Therefore, the purpose of this invention is to prevent the wall thickness of the tube from becoming thinner as much as possible due to the rolling process, and to form multiple ribs integrally and continuously on the entire outer circumferential wall in the longitudinal direction of the tube. The object of the present invention is to provide a ribbed steel pipe for use as a building reinforcement material that has a pipe shape.

[Means to solve the problem]

In order to achieve the above-mentioned problems, this invention consists of a series of a pair of upper and lower forming rolls arranged in series facing the direction of travel, and in the roll circumferential direction, one side has a convex portion with a nearly tapered tip, and the other side has a convex portion opposite to this. A special roll consisting of an upper roll and a lower roll with recesses is installed, and this special roll plastically deforms the steel strip into an uneven shape while further rolling it into a tubular shape. Abbreviation V
The inner wall of the tube is non-irregular, and the outer wall of the tube has convex ribs with a continuous metal structure in the protrusion direction and a smooth upper surface at minute intervals in the circumferential direction of the tube. It is characterized in that a plurality of tubes are integrally formed to protrude along the longitudinal direction of the tube body.

[Effect]

Therefore, unlike conventional steel pipes, the outer circumferential wall of the pipe has a rib structure that protrudes continuously and integrally in the longitudinal direction, and the metal structure of the ribs is continuous in the protruding direction, so the strength is exceptionally high. Moreover, the rib structure is not wave-shaped in cross section, but is almost solid and integrally protrudes from the outer peripheral wall of the tube, so the thickness of the tube does not become thinner, so the strength improvement due to the ribbing is ensured, and the overall strength of the tube is improved. Provides extremely high strength and durability. Furthermore, since the upper surface of the convex rib is a smooth surface, it retains the shape of a normal pipe as much as possible, so it can be used as an alternative to a conventional steel pipe in terms of shape.

〔Example〕

In FIG. 1, numeral 1 is a square-shaped ribbed steel pipe, and numeral 2 is a rib protruding from the entire circumferential surface of the outer wall along the longitudinal direction of the steel pipe. In other words, as shown in Fig. 2, when the tube is formed, it is simultaneously rolled into an uneven shape, and as a result of the extension of the plastic deformation, a convex shape with a continuous metal structure in the protrusion direction rises on the outer wall of the tube and has a smooth upper surface. The structure is such that the portion 3 is formed as a rib 2, and the substantially V-shaped groove 4 formed on the inner wall side is closed as much as possible, so that the inner wall surface of the tube is not uneven.
In this example, the dimension between the center of the convex part and the center of the convex part is l
It is composed of a unit cross section in which the wall thickness h ₁ of the tube wall is equal to the rising dimension of the convex portion from the outer surface of the tube wall.

Therefore, for example, FIGS. 3A and B, and also FIG.
As shown in Figures A and B, when comparing a ribbed square steel pipe and a so-called ribless square steel pipe by taking a unit cross section, even with the following theoretical values,
A dramatic improvement in strength was observed.

In addition, FIGS. 3A and 3B are unit cross-sectional views of a ribbed square steel pipe and a conventional ribless square steel pipe, respectively, when a bending moment is applied from a direction perpendicular to the horizontal plane of the steel pipe, and FIGS. 4A and B These are unit cross-sectional views when a bending moment is applied from the same direction to the vertical surface of the steel pipe. Also, b ₁ : Dimension between both ends of the concave part, b ₂ : Dimension between both ends of the convex part h ₂ : Dimension from the inner surface of the steel pipe to the top surface of the convex part e ₁ : Dimension from the axis Z-Z passing through the drawing center to the top surface of the convex part e ₂ : Dimensions I ₃ (A) and I ₃ (B) from the axis Z-Z to the inner surface of the pipe: Per unit cross-sectional area of the ribbed square steel pipe and ribless square steel pipe corresponding to Fig. 3 A and B, respectively. The second moment of inertia of the area, I ₄ (A), I ₄ (B): The second moment of inertia of the area corresponding to Figure 4 A and B, respectively, Z ₃ (A), Z ₃ (B): The second moment of area corresponding to Figure 3 A, respectively , cross section 2 corresponding to Figure 3B
Order coefficients, Z ₄ (A), Z ₄ (B): Section 2 corresponding to Figure 4 A and Figure 4 B, respectively.
It is the order coefficient.

Furthermore, for the conventional ribless type square steel pipe, for comparison, the pipe thickness t is the same as the wall thickness h ₁ of the recess of the ribbed steel pipe, and the unit width w is the dimension l between the recess center and the recess center. I'm doing the same.

First, I ₃ (A), Z ₃ (A) and
Calculating I ₃ (B) and Z ₃ (B), I ₃ (A) = 1/3 {le ₂ ³ − _{b 1} (e ₂ − h ₁ ) ³ + b ₂ e ₁ ³ } Z ₃ (A) =1/3e ₁ {le ₂ ³ −b ₁ (e ₂ −h ₁ ) ³ +b ₂ e ₁ ³ } Note that e ₁ = h ₂ −e ₂ e ₂ = b ₁ h ₁ ² +b ₂ h ₂ ² / 2 (h ₁ b ₁ + h ₂ b ₂ ) I ₃ (B) = 1/12wt ³ = 1/12lh ₁ ³ Z ₃ (B) = 1/6lh ₁ ² Also, I ₄ ( A), Z ₄ (A), I ₄
(B), Z ₄ (B), I ₄ (A) = 1/12 {h ₂ l ³ − (h ₂ − h ₁ ) b ₁ ³ } Z ₄ (A) = 1/6 l {h ₂ l ³ −(h ₂ −h ₁ )b ₁ ³ } I ₄ (B)=1/12h ₁ l ³ Z ₄ (B)=1/6h ₁ l ^2Now here, Z _A = Z ₃ (A ) + Z ₄ (A), Z _B = Z ₃ (B) + Z ₄ (B), h ₁ = 0.3 cm, h ₂ = 0.6 cm, b ₁ = 0.48 cm, l = 1.08 cm
If we compare the overall value using specific values as ∴Z _A /Z _B = 2.3, the ribbed square steel pipe according to this invention has approximately 2.3 times the strength compared to the conventional ribless square steel pipe. Appearance is recognized.

Since the ribs are formed using elongation due to plastic deformation, deformation will occur partially in the wall thickness of the tube, but since the wave shape is not uneven, even if this point is taken into account, the thickness will be at least twice as large. The above strength increase is achieved.

Furthermore, since the upper surface of the convex rib is a smooth surface, this type of steel pipe retains the shape of a normal pipe as much as possible, so that it can be used as an alternative to conventional steel pipes in terms of shape.

Moreover, when compared with conventional steel pipes, this type of steel pipe has the advantage that the space of the recesses created between the convex ribs can be used for material reduction. Of course, actual results vary somewhat depending on the thickness of the steel pipe, the degree of rib protrusion, and the spacing between ribs, but the fact remains that rib formation greatly contributes to material reduction for steel pipes.

A comparative explanation of this is as follows, taking as an example a rectangular steel pipe without ribs and a square steel pipe with a cross section of 6.0 cm on each side. In other words, a ribbed square steel pipe with a cross-sectional side of 6.0 cm can be obtained by reducing the wall thickness by approximately 15% using the material used for conventional 5.4 cm square steel pipes. Therefore, one side of the cross section is
Comparing the weights of the same 6.0cm square steel pipe, the pipe length is 100cm, the specific gravity is 7.85, and the wall thickness of the steel pipe without ribs.
2.3mm, and the wall thickness of the ribbed steel pipe is 2.0mm, the total weight W of the conventional square steel pipe without ribs is W = 24
(cm) x 0.23 (cm) x 100 (cm) x 7.85 = 4.33 (Kg), The total weight Wr of the ribbed square steel pipe of the present invention is Wr
= 21.6 (cm) x 0.23 (cm) x 100 (cm) x 7.85 = 3.90 (K
g) becomes. This means that if a square steel tube with a cross section of 6.0 cm on a side is provided as a ribbed square steel tube, the material will be reduced by approximately 9.9% compared to a conventional 6.0 cm square steel tube without ribs. . Therefore, if a conventional steel pipe is replaced with a ribbed steel pipe, a significant cost reduction can be achieved. On the other hand, when comparing this steel pipe in terms of strength, it is predicted from the value of 2.3 times the cross-sectional quadratic coefficient ratio calculated under the same thickness condition as described above, that it is at least equivalent to or better than the same 6.0 cm ribless rectangular steel pipe. It is clear that the strength is greater than that. Therefore, the ribbed rectangular steel pipe of the present invention has extremely great practical value in that material reduction and strength maintenance or improvement can be achieved at the same time. It would be possible to reduce the amount of material in a pipe with a corrugated cross-section in the same way, but the increase in surface area due to the corrugated shape is unavoidable, and this reduction would require the wall thickness of the pipe to be considerably thinner. However, it is difficult to achieve both economic efficiency and strength. Therefore, the present invention, which has both effects, is extremely practical in this type of application.

By the way, this type of steel pipe has ribs formed to protrude by extension of plastic deformation, and its forming is performed in the pipe manufacturing process of a so-called joint pipe as shown in Fig. 8, as shown in Fig. 8. This was achieved by incorporating a plurality of pairs of special rolls 5.

That is, in the pipe manufacturing process of the joint pipe, for example, as shown in FIGS. 6 and 7, the steel strip 7 is passed through a forming roll 6 in which a flat roll 6a and curved rolls 6b, 6c, 6d, and 6e are arranged in series. A forming section 8 that continuously forms a tube shape, a welding section 9 that heats and welds the joint by resistance heat using a tightening roll, a forming section 10 and a sizing section 11 that form a tube into a square shape. The forming section 8 has a convex portion 13 on one side and a convex portion 13 on the other side facing it, as shown in FIG. 8. recess 14
The special roll 5 provided with the
It is incorporated as c.

The special roll 5 is provided with convex portions 13 and concave portions 14 so that the unevenness of the tube gradually increases as it progresses from the first roll 5a to the second roll 5b to the third roll 5c. The part is particularly formed to have a substantially triangular shape with a tapered tip, and the forced rotation of the pair of rolls facilitates elongation of the material to be formed. Of course, the convex portion 13 or the concave portion 14 is not limited to this. For example, the tip of the convex portion 13 may be rounded, but it may be a convex portion that is approximately triangular and has a tapered tip. 13 is most preferred.

Further, in this example, the special roll 5 is a flat roll, and as shown in FIGS. 6 and 7, it is incorporated into the so-called flat roll 6a in the initial stage of the forming roll 6, and as shown in FIGS. An uneven surface is formed on the steel strip 7 at the initial stage of the section 8. Therefore, after this stage, the thickness of the gap between the pair of upper and lower forming rolls increases by the amount of rib formation, so the clearance between the rollers is adjusted appropriately at this point.

Although it is of course possible to provide the curved roll with an uneven surface, it is preferable to form the ribs on the roll at an early stage.

Note that the above-mentioned forming method relates to the ribbed square steel pipe according to the embodiment of the present invention, but the process may be changed as appropriate for various types of pipes such as round pipes. However, it is of course possible to adopt other methods for joining the pipes as appropriate. In short, a set of special rollers with a convex part on one side and a concave part on the other side are used to perform rolling at the same time as tube forming. Any method is acceptable as long as the V-shaped groove in the wall surface is closed as much as possible and a plurality of convex ribs are formed on the outer wall surface over the entire circumference along the longitudinal direction of the tube body.

[Effect of idea]

As described above, this idea causes plastic deformation in the strip steel to have an uneven and tubular shape almost simultaneously, and without forming an uneven surface on the inner wall surface, only the outer wall surface has continuous metal deformation in the protruding direction over the entire circumference. By providing a so-called ribbed steel pipe with structured ribs, we have achieved a dramatic increase in strength compared to conventional normal ribless steel pipes. Unlike iron pipes, solid ribs are formed protruding on the outer wall of the pipe body, and the inner wall surface has a non-irregular shape, so it can be made with the same or higher strength without becoming thinner and with relatively less material. Tube materials with the same diameter or width can be obtained. Furthermore, since the upper surface of the convex rib is a smooth surface, it maintains the shape of a normal pipe as much as possible, so that it can be used as an alternative to a conventional steel pipe in terms of shape, and has a particularly remarkable effect. Therefore, we were able to provide a ribbed steel pipe with extremely high practical value as a steel pipe for use as a building reinforcement material.

[Brief explanation of the drawing]

Fig. 1 is a front view showing an embodiment of the ribbed steel pipe according to this invention, Fig. 2 is a sectional view taken along the same line, and Fig. 3 is a sectional view taken along the same line.
Figures A and B are unit cross-sectional views located in the pipe horizontal plane of a ribbed square steel pipe and a ribless square steel pipe, respectively;
Figures 4A and B are unit cross-sectional views located on the vertical plane of the pipe, Figure 5 is a diagram of the tube manufacturing process of the square steel pipe, Figure 6 is a partial schematic diagram of the forming section in the same process, and Figure 7 is FIG. 6 is a schematic front view of each forming roller, and FIG. 8 is a schematic front view of a special roller used in an embodiment of this invention. 1... Steel pipe with ribs, 2... Ribs, 5... Special rolls, 13... Convex portions, 14... Concave portions.

Claims (1)

[Scope of utility model registration request] In the circumferential direction of the rolls, a pair of upper and lower special rolls consisting of an upper roll having a convex portion with a tapered tip and a lower roll having a concave portion at a position opposite to the upper roll, is used to roll the steel strip into its irregularities. By further rolling it into a tubular shape while plastically deforming it according to the shape, the approximately V-shaped groove formed in the upper part of the steel strip is almost closed, and the inner wall is non-irregular and the outer wall has a metal structure that is continuous in the protruding direction. 1. A ribbed steel pipe for construction reinforcement material, characterized in that a large number of convex ribs that stand upright and have a smooth upper surface are integrally formed in the longitudinal direction of the pipe body at minute intervals in the circumferential direction of the pipe body.