JP4312918B2

JP4312918B2 - Heavy corrosion protection method for steel

Info

Publication number: JP4312918B2
Application number: JP2000028497A
Authority: JP
Inventors: 豊男安藤; 正広遠藤; 明宏斉藤
Original assignee: Nippon Steel and Sumikin Anti Corrosion Co Ltd
Current assignee: Nippon Steel and Sumikin Anti Corrosion Co Ltd
Priority date: 2000-02-07
Filing date: 2000-02-07
Publication date: 2009-08-12
Anticipated expiration: 2020-02-07
Also published as: JP2001220694A

Description

【０００１】
【発明の属する技術分野】
例えば海水の干満帯は、鋼材にとって極めて苛酷な腐食環境である。このため例えば海洋構造物に用いる鋼材の干満帯には重防食被覆が施される。即ち例えば鋼材の表面に防食ペーストシートを貼り付け、更に防食ペーストシートの表面を厚さが２〜６ｍｍのポリエチレンシートで覆う防食方法が、重防食被覆として広く用いられている。この際、防食ペーストシートやポリエチレンシート等の防食材は、長期間に亘って鋼材表面から剥離する事なく、長期間に亘って鋼材表面を重防食する事が重要である。本発明は長期間に亘っても、防食材が鋼材表面から剥離する事がない、鋼材の重防食方法に関する。
【０００２】
【従来の技術】
鋼材表面への防食材の止着けは工場で行なう場合があるが、鋼構造物を構築した後で工事現場でその干満帯に防食材を止着ける場合もある。従って防食材の止め付けは水中でも実施できる事が好ましく、また鋼構造物が構築された後でも実施できることが好ましい。
【０００３】
特願平１０−１８５５７３号は、防食材と鋼材の双方を貫通するボルト挿通孔を穿孔し、有頭ボルトを防食材がない側の鋼材面からボルト挿通孔に挿通し、有頭ボルトの他端を防食材から突出せしめ、この他端にナットを螺合ししめつける方法を記載している。しかしながら鋼構造物を構築した後では、防食材がない側の鋼材面は、土砂やセメントで充填されている場合が多い。このため有頭ボルトを防食材がない側の鋼材面からボルト挿通孔に挿入するには、この土砂やセメントの除去が必要で、工事が厄介になる。従って工事現場で簡易に行なえる方法ではない。
【０００４】
例えば干満帯に配した防食材には、波浪による外力が繰り返し加わる。防食材の止着けが不確実な場合は、この繰り返す波浪の外力により防食材は鋼材表面から剥離する。特願平１０−１８５５７６号は、水中でも用いる事ができる鋲打銃を用いて、防食材側から鋼材面に向けて鋲を打ち込み、鋼材の表面に防食材を鋲で止着ける方法を記載している。この方法によると、防食材がない側の鋼材面が土砂やセメントで充填されている、構築が完了した後の鋼構造物の干満帯にも防食材を簡易に止着けることができる。しかし鋲による止着けは、長期間使用し得る十分に確実な止着け方法ではない。
【０００５】
工事現場で防食材を止着ける装置は、電源容量、装置の輸送方法、設備費用等の面から過大な装置は不適当で、簡易な装置である事が好ましい。図６は特願平１０−１８５５７２の防食材止着け方法の説明図である。即ち１または２以上の防食材４，５を鋼材２の表面に層状に配し、最外層の防食材５の表面に局所的な押え材６を配し、一端は鋼材２に連結され、防食材４，５と押え材６を貫通して他端は押え材から突出したねじ溝付き棒材１にナット３を螺合ししめつけて防食材４，５を鋼材２と押え材６により挾みつけて鋼材２の表面に止着ける方法である。図中８は例えば有機樹脂製のキャップであり、８１は有機樹脂系接着剤である。
【０００６】
図６（Ａ）において、ねじ溝付き棒材１は鋼材２に連結する。特願平１０−１８５５７２は、この連結に溶着または接着手段を用いると記載している。接着剤を用いる接着は簡易な連結手段ではあるが、十分な連結強度を長期間に亘って保持せしめる事は難しい。ねじ溝付き棒材１と鋼材２の連結を溶接により行なうと、十分な連結を長期間に亘って保持せしめることができる。
【０００７】
既に述べた如く、防食材の止着けは、水中でも行なえる方法である事が好ましい。ねじ溝付き棒材１と鋼材２を水中で溶接接合する方法としては、アークの発生が不必要な抵抗溶接法を用いる事が好ましい。しかしながら抵抗溶接は、抵抗熱のみによるため、アーク溶接に比較して数１０倍もの大電流を必要とする。また溶接機の容量が不十分な場合は、接合部に欠陥が発生し易い。また工場で用いるものと同程度の大容量の溶接機を用いると健全な接合部が得られるが、工事現場では大容量の溶接機の使用は馴染み難いという問題点がある。
【０００８】
【発明が解決しようとする課題】
本発明はこれ等の問題点を解決するもので、即ち、本発明は図６のねじ溝付き棒材１と鋼材２を、大容量の溶接機を用いることなく、水中で溶接接合して、健全な接合部を得る方法の提供を課題としている。
【０００９】
【課題を解決するための手段】
図１は本発明の方法の例の説明図である。本発明では１又は２以上の防食材４、５を鋼材２の表面に層状に配し、最外層の防食材の表面に局所的な押え材６を配する。防食材４には例えばペトロラタムペーストなどの防食剤を含浸させた不織布を用いる事ができる。また防食材５としてはポリエチレン樹脂、ポリウレタン樹脂、ポリ塩化ビニル樹脂製の厚さが２ｍｍ〜６ｍｍのシートを用いることができる。また押え材６としては高分子樹脂製の形材等を用いることができる。
【００１０】
本発明では、防食材４，５と押え材６を鋼材２の表面に止着けるが、その止着けは下記の如くに行なう。即ち押え材６を配した後で、押え材６側から押え材６と防食材４，５を貫通して鋼材２の表面に達した後、更に鋼材２の表面に直径が１〜３ｍｍの凹み７を形成する、ねじ溝付き棒鋼１の外径に見合った内径の挿通孔１０を穿孔する。
【００１１】
本発明においては、一端８を頂角３０〜１２０度の円錐状に形成した、直径が４〜１０ｍｍの、図１（Ｂ−１），（Ｂ−２）に図示したねじ溝付き棒鋼１を用いる。尚ねじ溝付き棒鋼１の円筒部分の外面には周方向のねじ溝が形成されている。本発明ではこのねじ溝付き棒鋼１を該一端８が該凹み７に当接するように該挿通孔１０に挿入し、抵抗溶接によりねじ溝付き棒鋼１の一端を鋼材２に溶接接合する。
【００１２】
本発明ではねじ溝付き棒鋼１の長さを所望の長さに選定する事により、ねじ溝付き棒鋼１の他端は押え材６から突出せしめる。また図１（Ｄ）の如くに突出した該他端にナット３を螺合ししめつけて、防食材４，５を、鋼材２と押え材６により挾みつけて鋼材２の表面に止着ける。尚必要により、高分子樹脂製のあるいは磁器性のキャップ８と、キャップ８に内蔵せしめた有機接着剤等を用いて、ねじ溝付き棒鋼１の他端とナット３を防食する。
【００１３】
図２は本発明の他の方法の例の説明図である。即ち押え材６を配した後で、押え材６側から押え材６と防食材４，５を貫通して鋼材２の表面に達した後更に鋼材２の表面に直径が１〜３ｍｍの凹みを形成する、ねじ溝付き棒鋼の外径に見合った内径の挿通孔を２本穿孔し、一端を頂角３０〜１２０度の円錐状に形成した直径が４〜１０ｍｍの２本のねじ溝付き棒鋼１−１，１−２のそれぞれを、該一端を該凹みに当接せしめてそれぞれの挿通孔に挿入し、一方のねじ溝付き棒鋼例えば１−１を溶接電源の正極に連結し、他方のねじ溝付き棒鋼例えば１−２を溶接電源の負極に連結して、２本のねじ溝付き棒鋼１−１，１−２を鋼材２に同時に抵抗溶接する方法である。この際には、溶接電流は点線矢印の如くに流れ、ねじ溝付き棒鋼１−１，１−２はシリーズ溶接によって同時に溶接される。
【００１４】
本発明はまた、防食剤４，５を鋼材２の表面に止着ける重防食が、すでに例えば工場で行われた鋼材が、使用の間に、防食材４，５が例えば消失しあるいは剥離して重防食が損傷した際の損傷部の補修方法として用いる事ができる。この際図１、図２の防食材４，５は、止着けが不良となったために再度止着ける防食材であり、あるいは補修用の新たな防食材である。この際にも押え材６を用いて本発明を行なうと、損傷部分には防食材４，５が確実に止着けられて、鋼材２の表面には再び重防食が施される。
【００１５】
【発明の実施の形態】
電気抵抗溶接においては、被溶接物の接点における電気抵抗により熱を発生させて被溶接物を加熱し接合する。空中での電気抵抗溶接では抵抗熱の逸散が少ないために、被溶接物は容易に加熱され接合される。しかし水中では抵抗熱が逸散するために接合が難しい。大容量の溶接電流を用いると大きな抵抗熱が得られて接合が容易になるが、工事現場においては大容量の溶接電流を用いる事は難しい。従って工事現場や水中で電気抵抗溶接を行なうには格別の工夫が必要となる。
【００１６】
本発明者当は、一次電源４０ＫＶＡ（１９０Ｖ〜４４０Ｖ）、二次出力７７００Ａの市販の空中で用いる直流簡易型抵抗溶接機を用いた。この程度の容量の抵抗溶接機は、工事現場においても使用する事ができる。
【００１７】
図３（Ａ）は有頭ボルトを抵抗溶接する際に用いる従来の溶接ガンである。この際にはホルダーの先端（右端）と鋼板でボルトヘッドを加圧して抵抗溶接する。従って溶接電流はボルトの幹には流れないで主としてホルダーの先端からボルトヘッドを経由して鋼板に流れる。
【００１８】
図３（Ｂ）は本発明の溶接ガンの例である。後で詳述するが、本発明で用いるねじ溝付き棒鋼にはボルトヘッドがない。従って本発明者等は図３（Ｂ）のごとく、ねじ溝付き棒鋼の後端（左端）に溶接電流が入り、ねじ溝付き棒鋼の幹を流れ、ねじ溝付き棒鋼の先端（右端）から鋼板に流れるように溶接ガンを改造した。また通常の有頭ボルトとは異なり、本発明のねじ溝付き棒鋼には、外周に、後でナットを螺合するためのねじ溝が設けられている。抵抗溶接に際しこのねじ溝が損傷する事を防止するために、溶接ガンの装着孔の内面には絶縁体を配した。
【００１９】
本発明では、一端を頂角３０〜１２０度に円錐状に形成した直径が４〜１０ｍｍのねじ溝付き棒鋼を用いる。本発明者等は板厚が２８ｍｍの炭素鋼鋼板の表面に頂角が９０度のドリルを用いて、直径が４ｍｍの凹みを形成した。この凹みに頂角が異なる直径７ｍｍの溝付き棒鋼を大気中で抵抗溶接した。表１はその結果の例である。本発明者等は、抵抗溶接を行なった後のねじ溝付き棒鋼をペンチで挾み、これに人力で曲げ応力を付与した。表中○は人力で曲げ応力をかけても折損しなかった場合で、×は折損した例である。
【００２０】
【表１】

【００２１】
表１にみられる如く、一端を頂角３０〜１２０度の円錐状とする事によって、ねじ溝付き棒鋼は強固に鋼板に溶接接合されている。この理由は必ずしも詳かではないが、円錐状の細い端部に溶接熱が集中し、溶接部の温度が効率よく上昇した事によると思われる。従って本発明のねじ溝付き棒鋼の一端は、頂角３０〜１２０度の円錐状に形成する。
【００２２】
尚本発明では直径が４〜１０ｍｍのねじ溝付き棒鋼を用いる。直径が４ｍｍ未満では防食材を止着ける強度が不十分である。しかし直径は１０ｍｍあれば十分である。重防食を施すに際しては、ねじ溝付き棒鋼の直径を１０ｍｍ超にするよりも、止付け個所を増やす方が、止付けは安定しかつ溶接電流が小さくなるために好ましい。
【００２３】
鋼材とねじ溝付き棒鋼を抵抗溶接する際には、溶接を施す部分の鋼材の表面にはスケールや異物がなく美麗である事が好ましい。研磨その他によってスケールや異物を鋼材の表面から除去する事も考えられるが、本発明においては図１（Ｂ−１），（Ｂ−２）に示す如く、押え材側から例えばドリルを用いて押え材と防食材を穿孔し、貫通してドリルの先端が鋼材の表面に達した後更に鋼材の表面に直径が１〜３ｍｍの凹みを形成する。
【００２４】
本発明者等は、鋼板の表面に直径が異なる凹みを形成し、直径が７ｍｍで先端の頂角が６０度のねじ溝付き棒鋼を、３％の食塩水中で、その先端をこの凹みに当接させて抵抗溶接により鋼材に溶接接合した。図４はその結果の例である。即ち凹みの径が小さいほど低入熱量で高強度の接合部が得られる。凹みの部分は小面積であるが、本発明の、先端が円錐状のねじ溝付き棒鋼を凹みに頭接させて抵抗溶接すると、凹みの近傍のスケールや有機物は抵抗溶接に際して押しのけられて、強固な接合部となる。尚凹みの直径が１ｍｍ未満では、抵抗溶接に際してねじ溝付き棒鋼の先端部の位置決めが不確実になり易い。しかし凹みの直径が３ｍｍ超で過大になると、図４にみられる如く、低入熱量の溶接で溶接部の引張強度は低くなる。
【００２５】
この凹み部分にも、海水中ではスケールが発生する。本発明者等は鋼板に凹みを形成し、海水中に放置し、その後溶接を行なった。図５は、この放置時間と溶接強度の関係を示す図である。図５にみられる如く、凹みを形成し、海水中に１２０分放置しその後溶接を行なっても、溶接部の引張り強度には大きな低下はない。尚１２０分は工事現場における重防食施工においても実施できる十分な時間である。
【００２６】
図２においいて、通常の抵抗溶接においては一本のねじ溝付き棒鋼（例えば１−１）を用い、溶接器の負極は鋼材２にアースクランプする。しかし電気抵抗による発熱は電流の方向に依存する事がない。従って溶接器の負極を鋼材２に連結しないで他のねじ溝付き棒鋼（例えば１−２）に連結する事により、１−１による抵抗溶接と１−２による抵抗溶接を同時に行なう事ができる。
【００２７】
【発明の効果】
本発明によると、大容量の溶接機を用いることなく、ねじ溝付き棒鋼を、水中で、鋼材に溶接接合し、十分な強度を有する安定な接合部を得る事ができる。従ってこのねじ溝付き棒鋼にナットを螺合ししめつけることにより、鋼板の表面に防食材は安定且つ確実に止め着けされて、長期に亘る使用の間にも防食材が剥離する事がない重防食鋼材が得られる。
【図面の簡単な説明】
【図１】は本発明の方法の例の説明図。
【図２】は本発明の他の方法の例の説明図。
【図３】は本発明で小する溶接ガンの例の説明図。
【図４】は本発明で形成する凹みの効果の説明図。
【図５】は凹み形成から溶接までの経過時間と溶接強度の関係を示す図。
【図６】は従来の重防食法の例の説明図。
【符号の説明】
１：ねじ溝付き棒鋼（スタッドボルト）、２：鋼材、３：ナット、４：防食材、５：防食材、６：押え材、７：凹み、８：ねじ溝付き棒鋼の一端（先端）、９：溶接金属、１０：挿通孔。[0001]
BACKGROUND OF THE INVENTION
For example, the tidal zone of seawater is a very severe corrosive environment for steel. For this reason, for example, a heavy anticorrosion coating is applied to the tidal zone of steel used for offshore structures. That is, for example, an anticorrosion method in which an anticorrosion paste sheet is attached to the surface of a steel material and the surface of the anticorrosion paste sheet is covered with a polyethylene sheet having a thickness of 2 to 6 mm is widely used as a heavy anticorrosion coating. At this time, it is important that the anticorrosive material such as the anticorrosive paste sheet and the polyethylene sheet is subjected to heavy anticorrosion on the steel material surface for a long period of time without peeling from the steel material surface for a long time. The present invention relates to a method for heavy corrosion protection of a steel material in which the corrosion protection material does not peel from the surface of the steel material over a long period of time.
[0002]
[Prior art]
The anti-corrosion material may be fixed to the steel surface at the factory, but the anti-corrosion material may be fixed to the tidal zone at the construction site after the construction of the steel structure. Therefore, it is preferable that the anticorrosive material can be fixed even in water, and it is preferable that the anticorrosive material can be fixed even after the steel structure is constructed.
[0003]
Japanese Patent Application No. Hei 10-185573 drills a bolt insertion hole that penetrates both the anticorrosion material and the steel material, and inserts the headed bolt into the bolt insertion hole from the steel material surface on the side without the anticorrosion material. A method is described in which the end is protruded from the anticorrosive material and a nut is screwed onto the other end. However, after the steel structure is constructed, the steel surface on the side without the anticorrosive material is often filled with earth or sand or cement. For this reason, in order to insert the headed bolt into the bolt insertion hole from the steel material side where there is no anticorrosive material, it is necessary to remove the earth and sand and the cement, which makes the construction troublesome. Therefore, it is not a method that can be easily performed at the construction site.
[0004]
For example, external forces caused by waves are repeatedly applied to the anticorrosive material arranged in the tidal zone. When it is uncertain that the anticorrosive material will stop, the anticorrosive material peels off the surface of the steel material due to the repeated external force of the waves. Japanese Patent Application No. 10-185576 describes a method of using a hammer that can be used even in water, driving a hammer from the anticorrosive material side toward the steel surface, and fixing the anticorrosive material to the surface of the steel material with a hammer. ing. According to this method, the anticorrosive material can be easily stopped even in the tidal zone of the steel structure after the construction is completed, in which the steel surface on the side without the anticorrosive material is filled with earth and sand or cement. However, fastening with a hook is not a sufficiently secure fastening method that can be used for a long time.
[0005]
The apparatus for fixing the anticorrosive material at the construction site is preferably an excessively large apparatus from the viewpoint of the power source capacity, the transportation method of the apparatus, the equipment cost, and the like, and is preferably a simple apparatus. FIG. 6 is an explanatory view of a method for fastening an anticorrosive material in Japanese Patent Application No. 10-185572. That is, one or two or more anticorrosion materials 4 and 5 are arranged in layers on the surface of the steel material 2, a local presser material 6 is arranged on the surface of the outermost anticorrosion material 5, and one end is connected to the steel material 2, The nut 3 is screwed into the bar 1 with thread groove protruding through the food materials 4 and 5 and the presser material 6 and the other end protruding from the presser material, and the anticorrosive materials 4 and 5 are clamped by the steel material 2 and the presser material 6. This is a method of fixing to the surface of the steel material 2. In the figure, 8 is a cap made of organic resin, for example, and 81 is an organic resin adhesive.
[0006]
In FIG. 6A, the threaded rod 1 is connected to the steel 2. Japanese Patent Application No. 10-185572 describes that welding or bonding means is used for this connection. Adhesion using an adhesive is a simple connection means, but it is difficult to maintain sufficient connection strength for a long period of time. When the threaded bar 1 and the steel 2 are connected by welding, sufficient connection can be maintained for a long period of time.
[0007]
As already described, it is preferable that the anticorrosive material is fastened in water. As a method of welding and joining the threaded rod 1 and the steel 2 in water, it is preferable to use a resistance welding method that does not require generation of an arc. However, resistance welding requires only a large amount of current that is several tens of times that of arc welding because it uses only resistance heat. In addition, when the capacity of the welder is insufficient, defects are likely to occur at the joint. In addition, when a large capacity welding machine similar to that used in a factory is used, a sound joint can be obtained, but there is a problem that it is difficult to get used to a large capacity welding machine at a construction site.
[0008]
[Problems to be solved by the invention]
The present invention solves these problems, that is, the present invention welds and joins the threaded rod 1 and the steel 2 in FIG. 6 in water without using a large-capacity welding machine, An object is to provide a method for obtaining a sound joint.
[0009]
[Means for Solving the Problems]
FIG. 1 is an explanatory diagram of an example of the method of the present invention. In the present invention, one or two or more anticorrosive materials 4 and 5 are arranged in a layered manner on the surface of the steel material 2, and a local presser material 6 is arranged on the surface of the outermost anticorrosive material. As the anticorrosive material 4, for example, a nonwoven fabric impregnated with an anticorrosive agent such as petrolatum paste can be used. As the anticorrosive material 5, a sheet made of polyethylene resin, polyurethane resin, polyvinyl chloride resin and having a thickness of 2 mm to 6 mm can be used. Further, as the presser member 6, a polymer resin shape or the like can be used.
[0010]
In the present invention, the anticorrosive materials 4 and 5 and the presser material 6 can be fixed to the surface of the steel material 2, and the fixing is performed as follows. That is, after the presser material 6 is arranged, the presser material 6 is passed through the presser material 6 and the anticorrosive materials 4 and 5 to reach the surface of the steel material 2, and then the surface of the steel material 2 is further recessed with a diameter of 1 to 3 mm. An insertion hole 10 having an inner diameter commensurate with the outer diameter of the threaded steel bar 1 is formed.
[0011]
In the present invention, the threaded steel bar 1 shown in FIGS. 1 (B-1) and (B-2) having a diameter of 4 to 10 mm, in which one end 8 is formed in a conical shape having an apex angle of 30 to 120 degrees. Use. In addition, the thread surface of the circumferential direction is formed in the outer surface of the cylindrical part of the steel bar 1 with a thread groove. In the present invention, the threaded steel bar 1 is inserted into the insertion hole 10 so that the one end 8 is in contact with the recess 7, and one end of the threaded steel bar 1 is welded to the steel material 2 by resistance welding.
[0012]
In the present invention, the other end of the threaded steel bar 1 is protruded from the presser member 6 by selecting the desired length of the threaded steel bar 1. Further, the nut 3 is screwed onto the other end protruding as shown in FIG. 1D, and the anticorrosive materials 4 and 5 are clamped by the steel material 2 and the presser material 6 to be fixed to the surface of the steel material 2. If necessary, the other end of the threaded steel bar 1 and the nut 3 are anticorrosive using a polymer resin or porcelain cap 8 and an organic adhesive incorporated in the cap 8.
[0013]
FIG. 2 is an explanatory diagram of another example of the method of the present invention. That is, after the presser material 6 is arranged, the presser material 6 is passed through the presser material 6 and the anticorrosive materials 4 and 5 to reach the surface of the steel material 2, and then a dent having a diameter of 1 to 3 mm is formed on the surface of the steel material 2. Two threaded steel bars having a diameter of 4 to 10 mm, each having a diameter of 4 to 10 mm, formed by drilling two insertion holes having an inner diameter commensurate with the outer diameter of the threaded steel bar to be formed 1-1, 1-2 are inserted into the respective insertion holes with one end abutting against the recess, and one threaded steel bar, for example, 1-1 is connected to the positive electrode of the welding power source, and the other This is a method in which a threaded steel bar, for example, 1-2 is connected to the negative electrode of the welding power source, and two threaded steel bars 1-1 and 1-2 are simultaneously resistance welded to the steel material 2. At this time, the welding current flows as shown by dotted arrows, and the threaded steel bars 1-1 and 1-2 are simultaneously welded by series welding.
[0014]
The present invention also provides that the anticorrosives 4 and 5 have disappeared or peeled off during use, for example, when a steel material that has already been used in a factory has been subjected to heavy anticorrosion to secure the anticorrosives 4 and 5 to the surface of the steel material 2. It can be used as a repair method for damaged parts when heavy corrosion protection is damaged. At this time, the anticorrosive materials 4 and 5 in FIG. 1 and FIG. 2 are anticorrosive materials that can be reattached due to poor fastening, or new anticorrosive materials for repair. Also in this case, when the present invention is carried out using the presser material 6, the anticorrosive materials 4 and 5 are securely fixed to the damaged portion, and the surface of the steel material 2 is again subjected to heavy anticorrosion.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
In electrical resistance welding, heat is generated by the electrical resistance at the contact point of the work piece, and the work piece is heated and joined. In electric resistance welding in the air, since the resistance heat is less dissipated, the workpieces are easily heated and joined. However, bonding is difficult in the water because resistance heat is dissipated. When a large-capacity welding current is used, a large resistance heat is obtained and joining becomes easy, but it is difficult to use a large-capacity welding current at the construction site. Therefore, special measures are required to perform electric resistance welding at a construction site or underwater.
[0016]
The present inventors used a DC simple resistance welding machine used in the air with a primary power supply of 40 KVA (190 V to 440 V) and a secondary output of 7700 A. A resistance welding machine with such a capacity can be used at a construction site.
[0017]
FIG. 3A shows a conventional welding gun used when resistance welding a headed bolt. At this time, the bolt head is pressurized with the tip (right end) of the holder and a steel plate and resistance welded. Accordingly, the welding current does not flow to the bolt stem, but flows from the tip of the holder to the steel plate via the bolt head.
[0018]
FIG. 3B is an example of the welding gun of the present invention. As will be described in detail later, the threaded steel bar used in the present invention does not have a bolt head. Accordingly, as shown in FIG. 3B, the present inventors enter welding current at the rear end (left end) of the thread grooved steel bar, flow through the trunk of the thread grooved steel bar, and from the front end (right end) of the thread grooved steel bar to the steel plate. Modified the welding gun to flow. Further, unlike a normal headed bolt, the threaded steel bar of the present invention is provided with a threaded groove for screwing a nut later on the outer periphery. In order to prevent the thread groove from being damaged during resistance welding, an insulator was provided on the inner surface of the mounting hole of the welding gun.
[0019]
In the present invention, a threaded steel bar having a diameter of 4 to 10 mm and having a conical shape with an apex angle of 30 to 120 degrees is used. The inventors of the present invention formed a dent having a diameter of 4 mm on the surface of a carbon steel plate having a thickness of 28 mm using a drill having a vertex angle of 90 degrees. A grooved steel bar having a diameter of 7 mm with a different apex angle was resistance-welded in the atmosphere to the recess. Table 1 is an example of the results. The present inventors squeezed the threaded steel bar after resistance welding with pliers, and applied bending stress to it with human power. In the table, ◯ indicates a case where breakage does not occur even when bending stress is applied by human power, and × indicates an example where breakage occurs.
[0020]
[Table 1]

[0021]
As can be seen in Table 1, the threaded steel bar is firmly welded to the steel plate by making one end conical with an apex angle of 30 to 120 degrees. The reason for this is not necessarily detailed, but it seems that the welding heat is concentrated on the conical narrow end portion, and the temperature of the welded portion is efficiently increased. Accordingly, one end of the threaded steel bar of the present invention is formed in a conical shape with an apex angle of 30 to 120 degrees.
[0022]
In the present invention, a steel bar with a thread groove having a diameter of 4 to 10 mm is used. If the diameter is less than 4 mm, the strength for fixing the anticorrosive material is insufficient. However, a diameter of 10 mm is sufficient. When carrying out heavy anticorrosion, it is preferable to increase the number of fastening points rather than making the diameter of the threaded steel bar more than 10 mm because the fastening is stable and the welding current is reduced.
[0023]
When resistance welding a steel material and a threaded steel bar, it is preferable that the surface of the steel material to be welded is free of scale and foreign matter and is beautiful. Although it is conceivable to remove scales and foreign substances from the surface of the steel material by polishing or the like, in the present invention, as shown in FIGS. 1 (B-1) and 1 (B-2), a presser is used from the presser material side using, for example, a drill. After drilling the material and the anticorrosive material and penetrating through and the tip of the drill reaches the surface of the steel material, a recess having a diameter of 1 to 3 mm is formed on the surface of the steel material.
[0024]
The inventors of the present invention formed a dent having a different diameter on the surface of a steel plate, and applied a threaded steel bar having a diameter of 7 mm and a tip apex angle of 60 degrees in 3% saline solution with the tip hitting the dent. The steel plates were welded and joined by resistance welding. FIG. 4 is an example of the result. That is, the smaller the diameter of the dent, the lower the heat input and the higher the strength of the joint. Although the dent portion has a small area, when the resistance-welded steel bar with a conical thread groove of the tip of the present invention is head-contacted with the dent, the scale and organic matter in the vicinity of the dent are pushed away during the resistance welding, so It becomes a proper joint. If the diameter of the dent is less than 1 mm, the positioning of the tip of the threaded steel bar tends to be uncertain during resistance welding. However, if the diameter of the dent exceeds 3 mm and becomes excessive, as shown in FIG. 4, the tensile strength of the welded portion is lowered by welding with a low heat input.
[0025]
A scale is also generated in seawater in this dent. The inventors formed a dent in the steel sheet, left it in seawater, and then welded it. FIG. 5 is a diagram showing the relationship between the standing time and the welding strength. As shown in FIG. 5, even if a dent is formed, left in seawater for 120 minutes and then welded, the tensile strength of the welded portion is not greatly reduced. 120 minutes is a sufficient time that can be carried out even in heavy anti-corrosion construction at the construction site.
[0026]
As shown in FIG. 2, in ordinary resistance welding, a single threaded steel bar (for example, 1-1) is used, and the negative electrode of the welder is grounded to the steel material 2. However, heat generation due to electrical resistance does not depend on the direction of current. Therefore, the resistance welding by 1-1 and the resistance welding by 1-2 can be simultaneously performed by connecting the negative electrode of the welder to another steel bar with a thread groove (for example, 1-2) without connecting to the steel material 2.
[0027]
【The invention's effect】
According to the present invention, a threaded steel bar can be welded and joined to a steel material in water without using a large-capacity welding machine, and a stable joint having sufficient strength can be obtained. Therefore, by screwing a nut into this threaded steel bar, the anti-corrosion material is securely and securely fastened to the surface of the steel plate, and the anti-corrosion material does not peel off even during long-term use. Steel material is obtained.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of an example of the method of the present invention.
FIG. 2 is an explanatory diagram of an example of another method of the present invention.
FIG. 3 is an explanatory view of an example of a welding gun to be reduced in the present invention.
FIG. 4 is an explanatory view of the effect of a dent formed in the present invention.
FIG. 5 is a view showing a relationship between an elapsed time from formation of a recess to welding and welding strength.
FIG. 6 is an explanatory diagram of an example of a conventional heavy anticorrosion method.
[Explanation of symbols]
1: Steel bar with thread groove (Stud bolt), 2: Steel material, 3: Nut, 4: Anticorrosive material, 5: Anticorrosive material, 6: Presser material, 7: Recessed, 8: One end (tip) of threaded steel bar, 9: weld metal, 10: insertion hole.

Claims

１又は２以上の防食材を鋼材の表面に層状に配し、最外層の防食材の表面に局所的な押え材を配し、一端は鋼材に連結され防食材と押え材を貫通して他端は押え材から突出したねじ溝付き棒鋼にナットを螺合ししめつけて防食材を鋼材と押え材により挾みつけて鋼材の表面に配する鋼材の重防食方法において、ねじ溝付き棒鋼と鋼材の連結が、押え材を配した後で押え材側から押え材と防食材を貫通して鋼材の表面に達した後更に鋼材の表面に直径が１〜３ｍｍの凹みを形成するねじ溝付き棒鋼の外径に見合った内径の挿通孔を穿孔し、一端を頂角３０〜１２０度の円錐状に形成した直径が４〜１０ｍｍのねじ溝付き棒鋼を該一端の先端を該凹みに当接せしめて該挿通孔に挿入し、ねじ溝付き棒鋼を鋼材に電気抵抗溶接するねじ溝付き棒鋼の鋼材への連結方法である事を特徴とする、鋼材の重防食方法。One or two or more anticorrosion materials are arranged in layers on the surface of the steel material, a local presser material is provided on the surface of the outermost anticorrosion material, and one end is connected to the steel material and penetrates the anticorrosion material and the presser material. In the heavy anti-corrosion method for steel, the end is screwed into a threaded steel bar projecting from the presser material and screwed into a nut to squeeze the anticorrosive material with the steel and the presser material. After connecting the presser material, the connection penetrates the presser material and the anticorrosive material from the presser material side and reaches the surface of the steel material. Then, a threaded steel bar having a diameter of 1 to 3 mm is formed on the surface of the steel material. An insertion hole with an inner diameter commensurate with the outer diameter is drilled, and a threaded steel bar with a diameter of 4 to 10 mm whose one end is formed into a conical shape with an apex angle of 30 to 120 degrees is brought into contact with the recess. A threaded steel bar is inserted into the insertion hole and is electrically resistance welded to a steel bar with a threaded groove. It characterized that it is a method of connecting to the timber, heavy duty method of steel.

請求項１の鋼材の重防食方法において、ねじ溝付き棒鋼の鋼材への連結が、押え材を配した後で押え材側から押え材と防食材を貫通して鋼材の表面に達した後更に鋼材の表面に直径が１〜３ｍｍの凹みを形成するねじ溝付き棒鋼の外径に見合った内径の挿通孔を２本穿孔し、一端を頂角３０〜１２０度の円錐状に形成した直径が４〜１０ｍｍのねじ溝付き棒鋼２本のそれぞれを、該一端の先端を該凹みに当接せしめてそれぞれの挿通孔に挿入し、一方のねじ溝付き棒鋼を溶接電源の正極に連結し他方のねじ溝付き棒鋼を該電源の負極に連結して、２本のねじ溝付き棒鋼を同時に鋼材に電気抵抗溶接するねじ溝付き棒鋼の鋼材への連結方法である事を特徴とする、請求項１の鋼材の重防食方法。The heavy corrosion prevention method for steel according to claim 1, wherein the threaded steel bar is connected to the steel material after the presser material is disposed and the presser material and the anticorrosive material are penetrated from the presser material side to reach the surface of the steel material. Two insertion holes with an inner diameter commensurate with the outer diameter of the threaded steel bar forming a dent with a diameter of 1 to 3 mm on the surface of the steel material are drilled, and one end has a conical shape with an apex angle of 30 to 120 degrees. Each of the 4 to 10 mm threaded steel bars is inserted into each insertion hole with its one end abutting against the recess, and one threaded steel bar is connected to the positive electrode of the welding power source and the other The threaded steel bar is connected to the negative electrode of the power source, and the two threaded steel bars are simultaneously electrically resistance welded to the steel material to connect the threaded steel bar to the steel material. Heavy steel corrosion protection method.

防食材が、鋼材の表面に接して配されたペトロラタムペーストを含浸せしめた不織布よりなる防食ペーストシートと、該防食ペーストシートの表面を覆って配された防食ポリエチレンシートの２枚の防食材である事を特徴とする、請求項１〜２の何れかに記載の鋼材の重防食方法。The anticorrosive material is an anticorrosive paste sheet made of a nonwoven fabric impregnated with petrolatum paste disposed in contact with the surface of the steel material, and an anticorrosive polyethylene sheet disposed so as to cover the surface of the anticorrosive paste sheet. The heavy corrosion protection method for steel according to any one of claims 1 to 2, characterized in that.

鋼材の重防食方法が、重防食がすでに施された後使用の間に重防食部が損傷した鋼材の該損傷部を補修する鋼材の重防食方法である事を特徴とする、請求項１〜３の何れかに記載の鋼材の重防食方法。The heavy corrosion prevention method of the steel material is a heavy corrosion prevention method of a steel material for repairing the damaged portion of the steel material in which the heavy corrosion prevention portion is damaged during use after the heavy corrosion protection has already been performed. 3. A method for heavy corrosion protection of steel according to any one of 3 above.

鋼材の重防食方法が、水中または海水中で行われる鋼材の重防食方法である事を特徴とする、請求項１〜４の何れかに記載の鋼材の重防食方法。The heavy corrosion prevention method for steel materials according to any one of claims 1 to 4, wherein the heavy corrosion prevention method for steel materials is a heavy corrosion prevention method for steel materials performed in water or seawater.