JP3505036B2 - Titanium sheet for building materials - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a titanium sheet for building materials, and more particularly to a titanium sheet for building materials.
In particular, the present invention relates to a titanium sheet for building materials having excellent shape freezing property during bending. 2. Description of the Related Art Large buildings and large recreational facilities such as airport terminal buildings, railway facilities, highway tollgates / restrooms, gymnasiums, exhibition halls, international convention centers, symbol towers, libraries, public halls, office buildings, and the like. In recent years, stainless steel sheets and titanium thin sheets have been frequently used as roofing materials, with emphasis on design, landscape, and durability. [0003] When stainless steel sheets or titanium sheets are used to construct roofing materials for these large building structures, usually,
The product is formed into a batch by a press bending machine having a bending mold of a longitudinal size of the product, or a thin plate wound into a coil is slit into a predetermined width to form a strip, and the multi-stage roll forming machine is used. To form a wide profile. Further, a construction method is adopted in which these are joined to each other by welding or fitting to cover a large area. At that time, both when using a bending mold and when using a roll forming machine, a so-called springback occurs in which the formed material is twisted around the longitudinal direction and a bending angle partially not obtained as designed is obtained. Therefore, it is known that the appearance as a building decreases. [0004] Springback is particularly remarkable in light bending with a small plastic working strain or bending with a large bending radius, and tends to occur when the degree of elastic strain is not negligible compared to the given plastic working strain. In particular, this springback is remarkable in a material such as a titanium material having a small Young's modulus. Conventionally, in order to suppress the occurrence of such springback, for example, reference has been made to “Cold Roll Forming” by Kenzo Kato (Nikkan Kogyo Shimbun, Showa 46, section 6.1.6). As described above, (1) an overbending method in which molding is performed in consideration of the amount of springback in advance, (2)
Measures have been taken such as applying pressure from the side using side rolls or the like. However, in the above-described method, considerable skill is required to estimate the springback amount in advance, and it takes time to adjust the jigs and rolls. In the case of a material having relatively large anisotropy in mechanical properties, the degree of freedom of material setting is limited. Further, for overbending, press bending and roll forming with a high load must be performed.
If this is done carelessly, not only will the roll and titanium adhere to each other, impairing the surface design of the molding material, but also the dimensional accuracy of the molded product will be reduced due to the wear of the molding die and the molding roll, and the wear will be reduced. In severe cases, it is necessary to replace the mold and rolls and re-machine. An object of the present invention is to provide a thin titanium sheet for building materials having a small springback amount and excellent shape freezing property when subjected to bending by roll forming or press forming without taking the above measures. And SUMMARY OF THE INVENTION The present inventor has proposed that a work-hardened portion is preliminarily formed on a thin plate material from the viewpoint that springback occurs because the amount of elastic strain during bending is not negligible compared to the composition strain. Are distributed in a large number, and the plastic strain of the forming is applied to the unhardened portion during bending and the amount of plastic strain per unit volume of the unhardened portion is increased, so that springback due to elastic strain can be prevented. I got the knowledge. According to the present invention, work hardened portions are formed at a plurality of locations on a titanium thin plate having a thickness T, and the width R, the depth H, and the interval L of the work hardened portions are 0.3 ≦ R / T ≦ 1.5. , 2 ≦ L / R ≦ 10,
A titanium sheet for building materials having excellent shape freezing characteristics, satisfying a relationship of 0.3 ≦ H / T ≦ 1. In the present invention, the depth H of the work hardened portion is
It refers to the depth of the work hardened portion in the thickness direction. In addition, the interval L between the work hardened portions refers to a distance between centers of adjacent work hardened portions in a certain direction. And the interval L and the width R of the work hardened portion in that direction are 2 ≦ L / R ≦ 10
To satisfy the relationship. DETAILED DESCRIPTION OF THE INVENTION The present inventor has proposed that a titanium thin plate (plate thickness T) be formed with a work-hardened portion in order to suppress the occurrence of springback, which is a problem when titanium is used as a building material. Appropriate distribution of the hardened parts was examined by a test. In the test, industrial pure titanium JIS one kind, two kinds, three kinds, Ti-3Al-2.5V alloy, β type alloy Ti-15
V-3Cr-3Al-3Sn thin plate (sheet thickness 0.2-1.
0 mm). Next, in order to provide local work hardened portions to these plates, cold rolling is performed using a work roll having a plurality of circular protrusions of various heights and various widths on the roll surface to form recesses in the plates. I let it. After the concave portions were formed, some of the materials were finished by rolling with a flat work roll having little unevenness. However, the total amount of rolling strain applied to the annealed plate was set to 7% or less. Next, the microstructure of the work-hardened portion applied to the material after rolling is observed, and the shape of the work-hardened portion hardened toward the center of the sheet thickness from the surface as a starting point (width R of the work-hardened portion).
And the depth H and the distance L) between the hardened portions were investigated. The degree of ringback is determined by the rolling direction (RD) of the annealed plate of the forming material.
A test piece (100 mm TD x 300 mm RD) taken from a direction corresponding to the direction perpendicular to the direction (TD) was subjected to a bending test using a mold so that the bending angle was 90 degrees with a bending radius of 5 mm using RD as a bending axis. . The angle of the inside of the bending portion of the test piece after the bending test was measured, and the difference between the value and 90 degrees was defined as the amount of springback. As a result of examining the relationship between the springback and the distribution state of the work hardened portion, in order to suppress the occurrence of springback, 0.3 ≦ R / T ≦
It was found that it was necessary to satisfy 1.5, 2 ≦ L / R ≦ 10, and 0.3 ≦ H / T ≦ 1. As a method of distributing the work hardened portions to the titanium sheet in the present invention, in the above test, a method was used in which a projection was provided on a work roll for cold rolling and the projection was pressed against the sheet. However, the method is not limited to this. Any method may be used. The microstructure of the work hardened portion can be easily observed because the mechanical twin density or the density of the slip line is high, and the shape (width R, depth H, interval L) of the hardened portion can be measured. For the observation, an etching solution usually used for chemical etching of titanium, for example, a nitric acid hydrofluoric acid aqueous solution may be used. As in the above test, when cold rolling is performed with a work roll having projections, and then rolling for smoothing the surface is performed, the maximum strain amount due to rolling must be 7% or less. Desirable so as not to impair the characteristics. Although the pattern of the processed portion may remain on the surface of the plate, the pattern can be easily erased by further performing shot blasting as necessary. Embodiments of the present invention will be described below. [Example 1] An industrially pure titanium JIS kind of annealed plate, the final annealing of which was performed in a vacuum annealing furnace, was rolled with work rolls having various distributions of projections, and the surface was then rolled up to a total of 7 including a surface smoothing roll. %, And a thin plate having a thickness of 0.209 mm was obtained. The shape of the work hardened portion was micro-observed, and an evaluation test of springback property was performed. The results show that, as shown in Table 1, when the ratio of the depth H of the work hardened portion to the plate thickness T is high, and the interval L between them is not too large as compared with the length R, the springback is reduced. Generation is suppressed. On the other hand, if H is too small, springback occurs. [Table 1] Example 2 A test similar to that of Example 1 was performed using a thin plate of (α + β) -type Ti-3Al-2.5V alloy that was finally annealed in a vacuum annealing furnace. The total amount of rolling was 5%, and the thickness was 0.299 mm. As shown in Table 2, when the work hardened portions are distributed so as to satisfy the conditions of the present invention, the occurrence of springback can be suppressed. [Table 2] Example 3 An industrially pure titanium JIS kind of annealed product coil in which the final annealing was performed in a vacuum annealing furnace was rolled by 5% with a work roll having various projections, and then the surface was flattened. Thin plate without rolling (sheet thickness 0.509
mm) was performed. As shown in Table 3, it can be seen that the size and distribution of the work hardened portions greatly affect the springback property even when the surface smoothing rolling is omitted. Then, the ratio of the depth of the work hardened portion to the plate thickness, the width of the work hardened portion and the interval at which the work hardened portions are distributed are defined within the conditions of the present invention,
The ratio of the composition strain / elastic strain at the time of bending is changed, and as a result, the occurrence of springback can be suppressed. [Table 3] Example 4 The final annealing was performed in the air, and then the two types of industrial pure titanium JIS thin sheet coils which had been subjected to salt treatment and pickling were rolled by 3% with a work roll having projections. , Including the subsequent surface smoothing and rolling
%, A springback property evaluation test was performed on a thin plate (thickness: 0.697 mm). As shown in Table 4, the effect of providing the work hardened portion is the same for the material that has been subjected to the pickling treatment, and no springback occurs when the material satisfies the conditions specified in the present invention. [Table 4] Example 5 β-type Ti-15V-3C which was subjected to final annealing in the air and then subjected to salt treatment and pickling
Springback of a thin plate (1.03 mm in thickness) in which the r-3Al-3Sn alloy is rolled by 3% with a work roll having protrusions and then rolled by a total of 4% including surface smoothing rolling A sex evaluation test was performed. As shown in Table 5, even when the material is a β-type alloy and has been subjected to the pickling treatment, a work hardened portion satisfying the conditions of the present invention is provided inside the material, so that the occurrence of springback occurs. Is suppressed. [Table 5] The titanium sheet for building material of the present invention has a problem when it is mainly processed as a building material for roof by specifying the size of work hardened portions introduced into the sheet and their distribution. It is possible to suppress the occurrence of springback during roll forming or press forming, and it is excellent in shape freezing properties, so it is suitable for use as a building material. This eliminates the need for an avoidance measure, thereby improving production efficiency and economy.

Claims (1)

(57) [Claims 1] A work hardened portion is formed at a plurality of locations on a titanium thin plate having a thickness T, and the width R, the depth H, and the interval L of the work hardened portion are
0.3 ≦ R / T ≦ 1.5, 2 ≦ L / R ≦ 10, 0.3 ≦
A thin titanium sheet for building materials having excellent shape freezing properties, which satisfies the relationship of H / T ≦ 1.