JP3605456B2 - H-beam joining method - Google Patents

Description

【００７３】
【表２】

【００７４】
加熱温度が１１５０℃未満ではインサート材の拡散不足が生じ、１３００℃超では変形大と材質劣化が生じるので、１１５０〜１３００℃を目標加熱温度とし、１２００〜１２５０℃を最適加熱温度範囲とした。
【００７５】
周波数が２ｋＨｚではいずれの箇所も温度が１２００℃に達しない。そのなかで周波数の影響を受けにくいと考えられるＮｏ． ３位置およびＮｏ． １０位置では、最も温度が高くなっている。反対に、周波数の影響を受けやすいと考えられるＮｏ． ７位置では、最も低温となっている。周波数が６ｋＨｚの場合も同様の傾向である。
【００７６】
しかし、周波数が１３ｋＨｚになると、Ｎｏ． ３位置とＮｏ． ７位置の温度が逆転し、その温度差も１０℃と小さく、いずれも１２００〜１２５０℃の最適温度範囲内に収まっている。
【００７７】
周波数が４０ｋＨｚでは、周波数が高くなることによる表皮効果によって温度が下がり、板厚が薄いウエブ中央のＮｏ． ７位置で温度が最も高くなる。
【００７８】
これらの結果は以下に示す計算式によっても裏付けられる。
【００７９】
平板を能率的に加熱するための最低許容周波数は
ｆ≧１５８・ρ／μｔ^２ （Ｈ_２ ）
ｆ：周波数（Ｈｚ）
ρ：固有抵抗（μΩｃｍ）
μ：比透磁率
ｔ：被加熱厚さ（ｃｍ）
となる。ここで
Ｐ＝５．０３〔ρ／（μ×ｆ）〕^１／２
Ｐ：電流浸透深さ（ｃｍ）
であり、ｔ／Ｐ≒２．５のときに吸収電力は最大となるから、１０ｔ，１３ｔ，１５ｔに最適の周波数は表３のようになる。
【００８０】
【表３】

【００８１】
Ｈ形鋼では浸透深さの影響を受けやすいウエブに合わせて周波数を設定する必要があり、８０／ｔ〜３００／ｔの範囲が望ましい。具体的には、３００Ｈを対象としたときは、ウエブの板厚は１０ｍｍであり、周波数としては２０ｋＨｚが最適であり、１５〜２５ｋＨｚが特に望ましい範囲である。４００Ｈを対象としたときは、ウエブの板厚が１３ｍｍであるので、周波数としては１５ｋＨｚが最適であり、１０〜２０ｋＨｚが特に望ましい範囲となる。５００Ｈを対象としたときは、ウエブの板厚が１５ｍｍであるので、周波数としては８．７ｋＨｚが最適となり、５〜１５ｋＨｚが特に望ましい範囲となる。
【００８２】
以上の検討結果を踏まえ、図２の加熱コイルを使用し、２０ｋＨｚの周波数で３００Ｈを実際に接合した。接合時間は１０分（一定）である。
【００８３】
インサート材の種類を種々変更したときの結果を表４に示す。接合条件は初期圧３．０ｋｇｆ／ｍｍ^２ 加熱温度１２００℃、アプセット量６．０ｍｍとした。また、シールドガスは加圧力が２．４ｋｇｆ／ｍｍ^２ に低下した時点で供給を停止した。表４中の母材破断に至ったＩ７のインサート材を使用し、接合条件を種々変更したときの結果を表５に示す。
【００８４】
表４および表５から分かるように、本発明の方法によりＨ形鋼が２本継ぎされる。実際の施工では母材破断が求められることを考慮すると、インサート材の成分組成としてはＢ１〜５％、Ｃｒ２０％以下（０を含む）、Ｓ：１０％以下（０を含む）、Ｐ１２％以下（０を含む）が適当である。また、初期圧としては０．８〜４．０ｋｇｆ／ｍｍ^２ 、シールドガスの供給を停止する時期としては初期圧の８０〜５０％到達時、アプセット量としては２〜７ｍｍ以上がそれぞれ適当である。ちなみに３００Ｈの接合にアーク溶接を用いると３０分以上の時間がかかる。
【００８５】
【表４】

【００８６】
【表５】

【００８７】
次に、実際の接合における周波数の影響および加熱コイルの標準クリアランスの影響を調査した。
【００８８】
Ｈ形鋼は上記接合と同じ３００Ｈを用いた。インサート材は表６のものを用いた。共通接合条件は加熱温度が１２５０℃、保持時間が３００秒、アプセット量が６ｍｍ、接合雰囲気が窒素ガスである。接合後のウエブ接合部およびフランジ接合部からＪＩＳ Ｚ３１２１の１号試験片を採取し、継手引張性能を評価した。周波数およびクリアランスを表７に示し、調査結果を表８に示す。表８より周波数は８０／ｔ〜３００／ｔ、クリアランスはｔ／２〜２ｔの望ましいことがわかる。
【００８９】
【表６】

【００９０】
【表７】

【００９１】
【表８】

【００９２】
【発明の効果】
本発明のＨ形鋼の接合方法は、各部で肉厚が異なるＨ形鋼を短時間で且つ安定した品質で冶金的に２本継ぎすることができる。従って、地下鉄工事でのＨ形鋼埋設のように短尺のＨ形鋼を次々と継ぎ足しながら埋め込んで行く工事に適用して、工期短縮、工事費低減等に大きな効果を発揮する。
【図面の簡単な説明】
【図１】Ｈ形鋼の拡散接合でのふくれの問題を示す模式図である。
【図２】本発明のＨ形鋼の接合方法に使用される加熱コイルの１例を示す平面図である。
【図３】同加熱コイルを用いた加熱ヘッドの１例を示す平面図である。
【図４】Ｈ形鋼の接合部のふくれ量を示す模式図である。
【図５】温度測定位置を示す模式図である。
【図６】Ｈ形鋼の高周波誘導加熱での周波数と加熱温度との関係を示すグラフである。
【図７】本発明のＨ形鋼の接合方法に使用される接合装置の１例についてその外観を示す斜視図である。
【図８】同接合装置の内部構造を模式的に示す正面図である。
【図９】同接合装置の内部構造を模式的に示す右側面図である。
【図１０】同接合装置の内部構造を模式的に示す左側面図である。
【図１１】同接合装置の内部構造を模式的に示す平面図である。
【図１２】同接合装置の内部構造を模式的に示す横断平面図である。
【図１３】同接合装置の動作を示す模式平面図である。
【図１４】同接合装置の動作を示す模式側面図である。[0001]
TECHNICAL FIELD OF THE INVENTION
INDUSTRIAL APPLICABILITY The present invention relates to an H-shape steel suitable for a double splicing of an H-shape in a construction site such as a subway construction and a temporary retaining work.Joining methodAbout.
[0002]
[Prior art]
2. Description of the Related Art As is well known, construction work such as subway construction and temporary retaining work for burial is being actively carried out for burying H-shaped steel pieces while sequentially adding them. The double splicing of the H-section steel at such a construction site has hitherto been performed by arc welding or mechanical joints using bolts.
[0003]
[Problems to be solved by the invention]
However, arc welding takes a long time to perform. Even if it takes a long time to perform the construction, if the construction is to be carried out on the open side, as in the case of temporary retaining work, since a long H-section steel can be used and the number of joints can be reduced, there is no particular problem. However, when construction is performed in a space with a limited height such as in subway construction, the length of the H-section steel is significantly limited, and the number of joints increases in proportion to this. In that case, the length of the arc welding time becomes a problem, and most of the H-section steel burial work is occupied by the welding work. Accordingly, the efficiency of burying H-section steel in subway construction is extremely low.
[0004]
In addition, in the field joining of H-section steel by arc welding, it is difficult to ensure the quality, and the variation in quality is also a major problem.
[0005]
On the other hand, mechanical joints using bolts are unsuitable for burial work because the pad and the heads of the bolts drag the surrounding soil at the time of driving.
[0006]
SUMMARY OF THE INVENTION An object of the present invention is to provide an H-shaped steel capable of metallurgically joining two H-shaped steels in a very short time and with stable quality even in a bad environment such as a construction site.Joining methodIs to provide.
[0007]
[Means for Solving the Problems]
The present inventors have been studying a liquid phase diffusion bonding method for pipes and strips using a low melting point insert material. In this joining method, materials to be joined are butted with a low melting point insert material interposed therebetween, the butted portion is pressurized, and high-frequency induction heating is performed to a temperature equal to or higher than the melting point of the insert material and lower than the melting point of the material to be joined. Joining can be performed in a short time that is incomparable to welding and with stable quality. Here, as for pressurization, it is general that heating is started in a state where an initial pressure is applied, and forcible pressurization is performed during heating.
[0008]
Although this joining method has been applied to on-site joining of steel pipes and rebars and has achieved great results, no attempt has been made to apply it to H-section steel.
[0009]
The joining method of the H-section steel according to the present invention is characterized in that the H-section steel is butted with a low-melting point insert material interposed therebetween, the butt portion is pressurized, and high-frequency induction is performed at a temperature not lower than the melting point of the insert material and lower than the melting point of the H-section steel. By heating, even in a bad environment such as a construction site, two H-sections are metallurgically spliced in a very short time and with stable quality.
[0010]
The present inventors also conducted research on the problems in applying the liquid-phase diffusion bonding method using a low-melting-point insert material to the joining of H-section steels and the solution thereof. As a result, the following facts became clear.
[0011]
First, unlike a steel pipe or a reinforcing bar, an H-section steel has a flange and a web having different thicknesses, so that it is difficult to perform high-frequency induction heating of a butt portion. For example, an H-section steel called 300H is 300H x 300B x 10t (web thickness) x 15t (flange thickness), and 400H is 400H x 400B x 13t (web thickness) x 21t (flange thickness). Even if such an H-section steel is to be joined based on experience gained in joining steel pipes and steel bars, the butted portion is not sufficiently heated.
[0012]
In this regard, it is effective to set the frequency used for high-frequency induction heating of the butted portion to a frequency at which currents on both sides of the H-section steel web do not cancel each other and each current does not concentrate on the web surface. Yes, specifically, the frequency is
80 / t ≦ f ≦ 300 / t
f: frequency (kHz)
t: Web thickness of H-section steel (mm)
It is desirable to satisfy the following.
[0013]
Second, as a heating coil used for high-frequency induction heating of the butted portion, as shown in FIG. 1, an H-shaped annular coil 2 surrounding the butted portion of the H-shaped steel 1 along its outer surface is required. However, the abutting portion undergoes blistering due to the upset caused by pressurization, and the blistering becomes non-uniform due to the characteristic shape of the H-section steel in which the web and the flange are combined. Therefore, when the heating coil is brought close to the butting portion, contact occurs, and when the heating coil is moved away from the butting portion, insufficient heating or uneven heating occurs.
[0014]
In order to solve this problem, it is effective to use a heating coil with a deformed coil that curves outward so that the distance to the butting portion is almost equal in each portion in a state where the butting portion in the coil has blistered due to pressure. is there. The distance is
t / 2 ≦ x ≦ 2t
x: distance (mm)
t: Web thickness (mm)
Is desirably within the range.
[0015]
Next, the H-section steel of the present inventionJoining equipment used for joining methodWill be described.
[0016]
Of the present inventionUsed for joining H-beamsThe joining device grasps each end of the two H-shaped steels in order to abut the two H-shaped steels to be joined, and a pair of clamps, each of which is forcibly driven in a contact / separation direction, and a pair of clamps And a high-frequency heating coil formed in an H-shaped annular body so as to surround the butted portion of the two H-shaped steels.
[0017]
In the case of burying H-section steel, one clamp is attached to the upper end of the H-section steel that has been buried, and the other clamp is attached to the lower end of the H-section steel held above the H-section steel. By forcibly driving the pair of clamps in the approaching direction with the insert material being sandwiched between the end faces of the two H-beams, the butted two H-beams are pressed. Then, the high-frequency induction heating of the butted portion by the heating coil between the pair of clamps during pressurization allows the two H-shaped steels to be metallurgically joined in a very short time and with stable quality.
[0018]
The present inventors have also conducted research and investigation on problems when using such a bonding apparatus and methods for solving the problems. As a result, the following facts became clear.
[0019]
First, when butting two H-beams, it is necessary to accurately align them in a plane perpendicular to the longitudinal direction. In this regard, each clamp has a first clamp cylinder that presses one flange of an H-section steel and presses the other flange against a reference surface, and a first clamp cylinder that presses one side of an H-section web and presses the other side. It is effective to provide a second clamp cylinder that presses the second clamp cylinder against the reference surface.
[0020]
Second, even though the H-section steels have the same size, there is a difference in the angle between the flange and the web, and the H-shaped steels cannot be said to have the same shape. Therefore, even if the flange and the web are pressed against the respective reference surfaces in the clamp, the two H-shaped steels may not be able to completely abut each other. In order to cope with this, it is effective to provide a correction cylinder for pressing each back surface of a pair of flanges on both sides of the H-section steel web and pressing each front surface to a reference surface.
[0021]
Third, in heating the butted portion, it is necessary to accurately align the butted portion and the heating coil in the longitudinal direction of the H-beam. In this regard, a high-frequency induction heating coil is mounted on one of the clamps, and when the clamp is attached to the end of the H-shaped steel, the high-frequency induction heating coil is brought into contact with the end surface of the H-shaped steel and the end surface thereof is used as a reference.H-section height in the longitudinal directionIt is effective to attach a movable stopper for setting to the other clamp.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with respect to a bonding method.
[0023]
In the joining method of the present invention, first, two H-section steels are butted with a low melting point insert material interposed therebetween.
[0024]
As the insert material, one or more of B1 to 5%, Cr20% or less, Si10% or less, P12% or less in which B is indispensable is included, and the balance is Ni composed of Ni and unavoidable impurities. A base alloy is preferred.
[0025]
B is an effective melting point lowering element. If it is less than 1%, the function as a melting point lowering element is insufficient, and the melting point becomes high. If it exceeds 5%, it takes a long time for diffusion, and a brittle intermetallic compound is formed.
[0026]
Cr contributes to ensuring the corrosion resistance of the joint, but if it exceeds 20%, the melting point increases and the wettability of the joint deteriorates.
[0027]
Si and P are also melting point depressing elements. However, if Si exceeds 10% and P exceeds 12%, diffusion is delayed and an embrittlement layer is formed at the joint interface.
[0028]
It is desirable to adjust the total amount of the melting point lowering element so that the melting point of the insert material is around 1000 ° C.
[0029]
The reason why the insert material is Ni-based is that the wettability with the base material is good, and the allowable range such as the roughness of the joint end face can be expanded.
[0030]
When the butting is completed, the butting portion is pressurized and heated.
[0031]
As for the pressurization, a pattern is preferably applied in which an initial pressure is applied before the start of heating, heating is performed in this state, and no forced pressurization is performed during heating. When heating is started with the initial pressure applied, the upset proceeds with the softening of the butted portion. In the joining method of the present invention, unlike the rebar or the like, it is desirable to use a method in which the upset is gradually applied by softening during heating only by the initial pressure applied before the start of heating, and in particular, the upset is advanced without applying external force. This is because a large bulge such as a reinforcing bar is not required, and a small bulge can be sufficiently joined.
[0032]
0.8 to 4.0 kgf / mm as initial pressure²Is desirable. If the initial pressure is insufficient, the bonding end faces do not adhere sufficiently, resulting in poor bonding. Excessive initial pressure causes not only hardware problems but also buckling deformation of the joint.
[0033]
It is preferable to start shielding the butted portion with the front shield gas in parallel with the start of the initial pressure.
[0034]
The heating is high-frequency induction heating that can be heated to a high temperature in a short time. As the heating coil, it is preferable to use a modified coil described later. The heating temperature is set to be equal to or higher than the melting point of the insert material and equal to or lower than the melting point of the H-section steel from the property of liquid phase diffusion bonding, and is desirably 1200 to 1250 ° C. The reason will be described later.
[0035]
In heating, frequency is important along with heating temperature and heating coil. In an H-beam, there is a difference in wall thickness between the flange and the web, so it is necessary to select a relatively high frequency suitable for heating a thin web. At a relatively low frequency suitable for thick flanges, the penetration depth of the induced current in the web becomes so deep that the currents on both sides cancel each other out and the temperature does not rise sufficiently.
[0036]
A desirable frequency f (kHz) is 80 / t to 300 / t depending on the thickness t (mm) of the web. If the frequency is too low, the above-described current canceling phenomenon occurs on the web, and if it is too high, the immersion depth is insufficient, and the current on both sides is concentrated on the surface, and the central part in the thickness direction is insufficiently heated.
[0037]
When the butted portion is softened by heating, upset occurs due to the initial pressure described above. In the field joint of H-section steel, it is not possible to expect sufficient end face accuracy such as the degree of finish, surface roughness and GAP of the joint end face. Therefore, an upset is required to obtain stable joint performance even if the end face accuracy is somewhat poor. The upset amount is preferably 2 to 7 mm for 300H, 400H, and 500H. If the upset amount is insufficient, the joint performance will vary. If it is excessive, the bulge of the joint becomes large. This blister does not occur at all in some places as shown in FIG. An increase in blister means an increase in nonuniformity of the blister, and a variation in clearance between the heating coil and the inner material is increased to make it difficult to secure an appropriate temperature. Therefore, it is not good to make the blister larger than a certain value. The heating time is set so that an appropriate upset amount is obtained.
[0038]
When the butted portion is softened, the above-described initial pressure also decreases. By monitoring the pressing force with the pressure sensor, it is possible to determine whether the temperature and the upset amount are appropriate. By stopping the supply of the shielding gas when the pressure reaches 80 to 50% of the initial pressure, the shielding gas can be saved. In a state where the ratio does not reach 80%, the adhesion of the joint end surfaces is not completely completed. Therefore, when the shielding gas is stopped, the insert material is oxidized and the joint performance varies. Further, the insert material may not reach the melting point in some cases, which may cause a decrease in joint performance. Continuing to supply the shielding gas even after it becomes smaller than 50% is a waste of gas.
[0039]
Next, the heating coil used in the method of the present invention will be described in detail. A preferred heating coil is shown in FIG. FIG. 3 shows a heating head using the heating coil.
[0040]
The heating head has a configuration in which a gas jacket 20 is stacked below the heating coil 10. Both are H-shaped annular bodies surrounding the H-shaped steel.
[0041]
The heating coil 10 is a one-turn coil made of a square tube made of copper, and has a two-segment structure in which a web is centered and separated on both sides. The coil pieces 10A, 10B on both sides are electrically connected by pressing the heads 11A, 11B at both ends, and are independently cooled by cooling water supplied and discharged via the heads 11A, 11B and the like. One coil piece 10A is divided at a portion corresponding to one end of one flange, and is connected to a high-frequency power supply by a pair of leads 12, 12 extending from the divided portion. At the time of joining, the heating coil 10 is set so as to surround the butted portion of the H-shaped steel.
[0042]
The shape of the heating coil 10 is not a perfect H-shape corresponding to the cross section of the H-section steel, and when the butt portion is pressurized and heated to a predetermined upset amount to generate blisters, the distance to the butt portion is reduced. The portions facing the web and the portions facing both sides of the flange have outwardly curved shapes so as to be substantially equal to each portion.
[0043]
The gas jacket 20 has a two-part structure similarly to the heating coil 10, and shield gas is supplied to the lower chamber 22 from each of three gas supply pipes 21. The shielding gas supplied to the lower chamber 22 is blown upward through the upper chamber 23, and gas-shields a butt portion located inside the upper heating coil 10.
[0044]
The heating coil 10 and the gas jacket 20 are arranged with a gap in the vertical direction, and are connected via a spacer by a connecting tool (not shown). These are covered by a cover (not shown) from the outside.
[0045]
FIG. 4 shows the amount of bulge at the butted portion when an H-section steel of 300H was heated and pressed at an upset amount of 7 mm.
[0046]
When the shape of the heating coil 10 is represented by the distance (clearance) to the surface of the butted portion before deformation, the shape is obtained by adding a blister amount as shown in FIG. 4 to the standard clearance.
[0047]
When the heating coil 10 is used, the distance to the butting portion becomes substantially equal in each portion in a state where the butting portion is swollen, and the butting portion can be uniformly heated. The distance to the butted portion at this time is the standard clearance described above. That is, the heating coil 10 can manage the clearance of each part to the standard clearance when the butted part bulges.
[0048]
The distance x (mm) from the butt portion where blistering has occurred to the heating coil 10, that is, the desired value of the standard clearance is represented by the thickness t (mm) of the web, and is t / 2 to 2t. If the standard clearance is too small, the butted portion will approach the heating coil 10, and it will be difficult to remove the heating coil 10 after joining. Conversely, if it is too large, the heating efficiency will decrease, and proper heating within a predetermined time will not be possible. It will be difficult.
[0049]
next,Used in the method of the present inventionAbout joining equipmentexplain.
[0050]
FIG. 7 shows the present invention.Used in the wayFIG. 8 to FIG. 12 are perspective views showing the appearance of one example of the joining apparatus, and FIGS. 8 to 12 schematically show the internal structure of the joining apparatus.Is9 is a right side view, FIG. 10 is a left side view, FIG. 11 is a plan view, and FIG. 12 is a cross-sectional plan view. FIGS. 13 and 14 are schematic views showing the operation of the joining apparatus.
[0051]
As shown in FIGS. 7 to 12, the joining apparatus includes a pair of clamps 30, 30 connected at intervals and a heating head 40 disposed between the clamps 30, 30. Since this joining device is usually used to add another H-beam 1 on top of a vertically buried H-beam 1, the clamps 30, 30 need to be distinguished when they need to be distinguished. The clamp 30 is called an upper clamp, and the lower clamp 30 is called a lower clamp in the figure.
[0052]
Both sides of the lower clamp 30 extend upward, and the upper clamp 30 is supported between the extending portions so as to be able to move up and down. Except for this, the clamps 30, 30 have basically the same structure, are connected at the rear so as to be able to freely contact and separate, and are forcibly driven in the approaching direction and the separating direction by the pair of left and right main cylinders 31, 31, respectively.
[0053]
Each of the clamps 30 is mounted on an end of the H-shaped steel 1 so that a pair of flanges of the H-shaped steel 1 face both sides, and grips the end. In order to facilitate mounting of the clamp 30 on the H-section steel 1, a one-sided door 32 is provided at the front of the clamp 30. The door 32 is driven to open and close by a horizontal cylinder 32a (FIG. 11) and is locked in a closed state by a vertical cylinder 32b (FIG. 8). The clamp 30 is provided with two types of clamp cylinders 33, 34 (FIGS. 9, 11, and 12) for gripping the H-section steel 1.
[0054]
One of the clamp cylinders 33 is horizontally arranged inside the door 32 in two upper and lower stages, presses the web of the H-section steel 1 in the clamp 30 from the front to the rear, and presses the web to a vertical reference surface in the clamp 30. Press on 35. The other clamp cylinder 34 is horizontally arranged in two upper and lower stages on one side of the clamp 30. Then, the clamp cylinders 34 press one flange of the H-shaped steel 1 in the clamp 30 via the head 37 toward the other flange, and press the other flange against a vertical reference surface 36 in the clamp 30. The front of the head 37 faces the reference surface 36 and is used as a reference surface at the time of a correction operation described later.
[0055]
Also provided within clamp 30 are four correction cylinders 38 (FIGS. 10, 11, and 12). The four correction cylinders 38 are horizontally arranged in two stages each on the front side and the rear side, and all face sideways. Then, these correction cylinders 38 synchronize and press the back surfaces of both flanges on both sides of the web of the H-beam 1 in the clamp 30.
[0056]
A tilting stopper 39 (FIG. 10) is provided below the upper clamp 30. The stopper 39 is tilted back and forth about the upper end by the cylinder 39a. In the backward tilted position, the upper clamp 30 does not interfere with the end of the upper H-shaped steel 1 when it is mounted on the end. I have. When the lower clamp 30 is attached to the upper end of the lower H-section 1 in the forward inclined position, the lower end of the stopper 39 contacts the upper end of the web of the H-section 1 and the upper end of the web is used as a reference. To perform the vertical positioning of the clamps 30, 30.
[0057]
The heating head 40 disposed between the clamps 30, 30 is supported on the lower clamp 30. The heating head 40 incorporates the above-described heating coil, and is divided into two parts including the heating coil. The front head unit 41 is installed on the door 32, and moves forward and backward by the operation of the cylinder 41a. The rear head unit 42 is directly connected to the rear transformer 50, and moves forward and backward together with the transformer 50 by the operation of the cylinder 42a.
[0058]
The heating coil in the heating head 40 has a constant height from the lower clamp 30, and the stopper 39 described above positions the clamps 30, 30 in the vertical direction based on the upper end surface of the web of the lower H-section 1. Is performed, the height is the same as the upper end surface of the web.
[0059]
Next, a method of using the present bonding apparatus will be described with reference to FIGS.
[0060]
When the lower H-shaped steel 1 is driven vertically into the ground, the door 32 of the lower clamp 30 is opened, and the upper end of the H-shaped steel 1 is placed on the lower clamp 30 as shown in FIGS. Then, the door 32 is closed.
[0061]
Thereby, as shown in FIG. 14A, the upper end of the H-shaped steel 1 penetrates through the inside of the lower clamp 30. At this time, the heating head 40 is open forward and backward. The stopper 39 is in the forwardly inclined position, and its lower end is in contact with the upper end surface of the web of the H-section steel 1. Thus, the clamps 30, 30 are positioned in the vertical direction with reference to the upper end surface of the web, and the heating coil in the heating head 4 is at the same height as the upper end surface of the web.
[0062]
After the vertical positioning of the clamps 30, 30, the following series of operations is performed in the lower clamp 30.
[0063]
13C, first, one flange of the H-section steel 1 is lightly pushed via the head 37 by one clamp cylinder 34 in the lower clamp 30, and the other flange is placed on the reference surface 36. Hit it. Subsequently, one surface of the web of the H-section steel 1 is lightly pressed by the other clamp cylinder 33, and the other surface is brought into contact with the reference surface 35. Then, the clamp cylinders 33 and 34 are simultaneously operated to strongly press the H-shaped steel web and the flange against the reference surfaces 35 and 36. As a result, the lower clamp 30 is coupled to the upper end of the H-beam 1, and the upper end is positioned in the clamp 30.
[0064]
When the positioning of the H-section steel 1 in the lower clamp 30 in the horizontal plane is completed, the correction cylinder 38 in the lower clamp 30 is operated synchronously. As a result, both flanges of the H-beam 1 are pressed against the reference surface 35 and the front surface of the head 37, and the end shape of the H-beam 1 is corrected.
[0065]
When the lower clamp 30 is mounted on the upper end of the lower H-section steel 1 in this way, the upper clamp 30 is slightly pushed up, the stopper 39 is returned to the backward tilt position, and then the upper clamp 30 is lowered to the original position.
[0066]
Next, as shown in FIG. 14 (b), the upper H-section steel 1 is placed on the lower H-section steel 1 and the lower end of the upper H-section steel 1 is made in exactly the same manner as described above. The upper clamp 30 is mounted. As a result, the H-section steel 1 in the upper clamp 30 is also positioned in the horizontal plane, and its end shape is corrected. Therefore, the upper and lower H-shaped steels 1, 1 are butted against each other. Also, the butted portion has the same height as the heating coil in the heating head 40.
[0067]
After the butting of the H-section steel 1 is completed, the upper clamp 30 is once raised, an insert material is inserted between the end faces of the H-section steel 1 and 1, and the upper clamp 30 is lowered again. Then, as shown in FIG. 14C, the heating head 40 is closed, the butting portion is subjected to high frequency induction heating by the heating coil in the heating head 40, and the clamps 30, 30 are drawn by the main cylinders 31, 31, butting is performed. Press the part.
[0068]
Since the upper and lower H-section steels 1, 1 are butted against each other, they are soundly joined. Further, since the butted portion is set at the same height as the heating coil, the joining can be completed within a predetermined time.
[0069]
【Example】
Examples of the method of the present invention will be shown below, and the effects of the method of the present invention will be clarified by comparison with comparative examples.
[0070]
300H (web thickness: 10 mm, flange thickness: 15 mm) specified in JIS A5526 SHK400 were butted, and the butt portion was subjected to high frequency induction heating. FIG. 4 shows the deformation of the butted portion when an upset amount of 7 mm is added. The heating coil designed in consideration of this deformation is shown in FIG. The numbers in FIG. 2 are the distance to the butted portion before deformation, that is, the design clearance (mm). The standard clearance was 12 mm.
[0071]
The relationship between the frequency and the temperature when the butted portion was heated using the coil of FIG. 2 was investigated. Temperature was measured with a thermocouple. The measurement position is shown in FIG. No. where the flange and web intersect. 3 and No. 3 Reference numeral 10 denotes a position that is considered to be hardly affected by the frequency during heating. On the other hand, No. 2 in the center of the web Reference numeral 7 denotes a position where the influence is considered to be the greatest. The results of the investigation are shown in Table 1 and FIG. No. No. 3 and No. Table 2 shows the temperature differences at the seven positions.
[0072]
[Table 1]

[0073]
[Table 2]

[0074]
If the heating temperature is lower than 1150 ° C, insufficient diffusion of the insert material occurs, and if it exceeds 1300 ° C, large deformation and material deterioration occur. Therefore, the target heating temperature was set at 1150 to 1300 ° C, and the optimal heating temperature range was set at 1200 to 1250 ° C.
[0075]
When the frequency is 2 kHz, the temperature does not reach 1200 ° C. at any point. Among them, No. 1 is considered to be hardly affected by frequency. No. 3 and No. 3 At the 10 position, the temperature is highest. Conversely, No. 1 is considered to be easily affected by frequency. At position 7, the temperature is the lowest. The same tendency is observed when the frequency is 6 kHz.
[0076]
However, when the frequency becomes 13 kHz, No. No. 3 and No. The temperatures at the seven positions are reversed, and the temperature difference is as small as 10 ° C, and all are within the optimal temperature range of 1200 to 1250 ° C.
[0077]
When the frequency is 40 kHz, the temperature decreases due to the skin effect caused by the increase in the frequency, and No. 2 in the center of the web having a small thickness is obtained. The temperature is highest at seven positions.
[0078]
These results are supported by the following calculation formula.
[0079]
The minimum allowable frequency for heating a flat plate efficiently is
f ≧ 158 · ρ / μt²(H₂)
f: frequency (Hz)
ρ: Specific resistance (μΩcm)
μ: relative permeability
t: Heated thickness (cm)
It becomes. here
P = 5.03 [ρ / (μ × f)]^1/2
P: Current penetration depth (cm)
Since the absorbed power becomes maximum when t / P ≒ 2.5, the optimal frequencies for 10t, 13t, and 15t are as shown in Table 3.
[0080]
[Table 3]

[0081]
In the case of the H-section steel, it is necessary to set the frequency in accordance with the web which is susceptible to the penetration depth, and a range of 80 / t to 300 / t is desirable. Specifically, when targeting 300H, the thickness of the web is 10 mm, and the optimal frequency is 20 kHz, and 15 to 25 kHz is a particularly desirable range. When 400H is targeted, the thickness of the web is 13 mm, so that the frequency is optimally 15 kHz, and 10 to 20 kHz is a particularly desirable range. When 500H is targeted, the web thickness is 15 mm, so that the frequency is optimally 8.7 kHz, and 5 to 15 kHz is a particularly desirable range.
[0082]
Based on the above examination results, 300H was actually joined at a frequency of 20 kHz using the heating coil of FIG. The joining time is 10 minutes (constant).
[0083]
Table 4 shows the results when various types of insert materials were changed. The joining condition is 3.0 kgf / mm of initial pressure.²The heating temperature was 1200 ° C. and the upset amount was 6.0 mm. The pressure of the shielding gas is 2.4 kgf / mm.²The supply was stopped at the time of the drop. Table 5 shows the results of various changes in the joining conditions using the insert material of I7 which resulted in the base material breakage in Table 4.
[0084]
As can be seen from Tables 4 and 5, two H-sections are spliced by the method of the present invention. Considering that base material fracture is required in actual construction, the composition of the insert material is B1-5%, Cr 20% or less (including 0), S: 10% or less (including 0), P12% or less (Including 0) is appropriate. Further, the initial pressure is 0.8 to 4.0 kgf / mm.²It is appropriate that the supply of the shielding gas is stopped when the pressure reaches 80 to 50% of the initial pressure, and the upset amount is 2 to 7 mm or more. By the way, if arc welding is used for joining at 300H, it takes 30 minutes or more.
[0085]
[Table 4]

[0086]
[Table 5]

[0087]
Next, the influence of the frequency and the effect of the standard clearance of the heating coil on the actual joining were investigated.
[0088]
The same 300H as the above-mentioned joining was used for the H-section steel. The insert material shown in Table 6 was used. The common bonding conditions are a heating temperature of 1250 ° C., a holding time of 300 seconds, an upset amount of 6 mm, and a bonding atmosphere of nitrogen gas. A JIS Z 3121 No. 1 test piece was sampled from the joined web and the joined flange to evaluate the joint tensile performance. Table 7 shows the frequency and clearance, and Table 8 shows the inspection results. From Table 8, it can be seen that the frequency is desirably 80 / t to 300 / t and the clearance is desirably t / 2 to 2t.
[0089]
[Table 6]

[0090]
[Table 7]

[0091]
[Table 8]

[0092]
【The invention's effect】
The H-section steel of the present inventionJoining methodCan metallurgically splice two H-section steels having different thicknesses in each part in a short time and with stable quality. Therefore, the present invention is applied to a construction in which short H-shaped steels are buried while being added one after another, such as the burial of H-shaped steels in subway construction, and has a great effect in shortening the construction period, reducing construction costs, and the like.
[Brief description of the drawings]
FIG. 1 is a schematic view showing a problem of blistering in diffusion bonding of an H-section steel.
FIG. 2 of the present invention.Used for joining H-beamsIt is a top view showing an example of a heating coil.
FIG. 3Same heating coilFIG. 3 is a plan view showing an example of a heating head using the hologram.
FIG. 4 is a schematic diagram showing the amount of bulge at the joint of an H-section steel.
FIG. 5 is a schematic diagram showing a temperature measurement position.
FIG. 6 is a graph showing a relationship between frequency and heating temperature in high frequency induction heating of an H-section steel.
FIG. 7 of the present invention.Used for joining H-beamsIt is a perspective view which shows the external appearance about an example of a joining device.
FIG. 8 is a front view schematically showing the internal structure of the joining device.
FIG. 9 is a right side view schematically showing the internal structure of the joining device.
FIG. 10 is a left side view schematically showing the internal structure of the joining device.
FIG. 11 is a plan view schematically showing the internal structure of the joining device.
FIG. 12 is a cross-sectional plan view schematically showing the internal structure of the joining device.
FIG. 13 is a schematic plan view showing the operation of the joining device.
FIG. 14 is a schematic side view showing the operation of the joining device.

Claims (4)

Butt H-beams across the insert material of low melting point, the butted portion with pressurized, and the high-frequency induction heating to a temperature below the melting point of the melting point or more H-beam of the insert material, H-shaped liquid phase diffusion bonding In the steel joining method, the frequency used for high-frequency induction heating of the butted portion is a frequency at which currents on both sides of the H-section steel web do not cancel out and each current does not concentrate on the web surface. ,
80 / t ≦ f ≦ 300 / t
f: frequency (kHz)
t: Web thickness of H-section steel (mm)
A method for joining H-shaped steel, characterized by satisfying the following. High-frequency induction heating coil, in claim 1 in which the abutted portion of the coil is the distance to the abutting portion in a state that caused the swelling due to pressure, characterized in that the curved outward so as to be substantially equal in each unit The method for joining an H-section steel according to the above description. H-shaped steel is butted with a low-melting-point insert material in between, and the butted portion is pressurized, and high-frequency induction heating is performed to a temperature equal to or higher than the melting point of the insert material and lower than the melting point of the H-shaped steel to perform liquid phase diffusion bonding. A method of joining steel, wherein a high-frequency induction heating coil surrounds a butt portion of the H-shaped steel along an outer surface thereof, and the butt portion in the coil extends to the butt portion in a state where blisters are generated by pressurization. A method for joining H-shaped steels, comprising using a heating coil curved outward so that the distance is substantially equal in each part . The distance from the butted portion of the blister to the heating coil is t / 2 ≦ x ≦ 2t
x: distance (mm)
t: Web thickness (mm)
The method for joining H-shaped steels according to claim 2 or 3 , wherein:

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