JP2013111586A - Resistance spot welding method for high-strength steel plate - Google Patents
Resistance spot welding method for high-strength steel plate Download PDFInfo
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本発明は、継手強度に優れる溶接部を形成する高強度鋼板の抵抗スポット溶接方法に関する。 The present invention relates to a resistance spot welding method for a high-strength steel sheet that forms a weld zone having excellent joint strength.
近年、車体の高信頼性と、エミッション削減を目的とした車体重量の軽減を両立して達成するための鋼板の高強度化が進められている。自動車の車体組立てにおいては、抵抗スポット溶接が広く用いられている。 In recent years, steel sheets have been strengthened to achieve both high reliability of the vehicle body and reduction of vehicle body weight for the purpose of reducing emissions. Resistance spot welding is widely used in the assembly of automobile bodies.
抵抗スポット溶接は、図１に示すように、重ね合わせた２枚以上の鋼板（ここでは、下の鋼板１と上の鋼板２の２枚）の板組３を、上下一対の電極チップ（下の電極チップ４と上の電極チップ５）で挟み、加圧、通電することにより溶融させ、必要サイズの径ｄのナゲット６を形成して、溶接継手を得るものである。
As shown in FIG. 1, resistance spot welding is performed by attaching a plate set 3 of two or more stacked steel plates (here, the lower steel plate 1 and the upper steel plate 2) to a pair of upper and lower electrode tips (lower The electrode tip 4 and the upper electrode tip 5) are sandwiched between the electrode tip 4 and the upper electrode tip 5) and melted by pressurization and energization to form a
このようにして得られた溶接継手の品質は、ナゲットの径ｄや溶け込みが得られているか、あるいはせん断引張強度（継手のせん断方向に引張試験をしたときの強さ）や十字引張強度（継手の剥離方向に引張試験をしたときの強さ）、または疲労強度などで評価されている。その中でも、せん断引張強度や十字引張強度を代表とする静的強度は、溶接継手の品質の指標として非常に重要視されている。 The quality of the welded joint thus obtained is that the nugget diameter d and penetration are obtained, or the shear tensile strength (strength when a tensile test is performed in the shear direction of the joint) or the cross tensile strength (joint Strength when a tensile test is performed in the peeling direction) or fatigue strength. Among them, the static strength represented by the shear tensile strength and the cross tensile strength is regarded as very important as an index of the quality of the welded joint.
このうち、スポット溶接部の引張せん断強度は、鋼板の引張強度の増加とともに増加する傾向にある。しかし、十字引張強度は鋼板の引張強度の増加にかかわらずほとんど増加せず、逆に減少する。その原因として、高強度鋼板は、その強度を達成するために下記（ア）式などで表される炭素等量Ｃｅｑが大きくならざるを得ず、加えて溶接は急熱急冷現象を伴うために、溶接部及び熱影響部において硬度が上昇し、靭性が低下するからだと考えられている。 Among these, the tensile shear strength of the spot welded portion tends to increase as the tensile strength of the steel plate increases. However, the cross tensile strength hardly increases regardless of the increase in the tensile strength of the steel sheet, but decreases. As a cause of this, high strength steel sheet has to have a large carbon equivalent Ceq represented by the following formula (A) in order to achieve its strength, and in addition, welding involves a rapid heating and quenching phenomenon. It is considered that the hardness is increased and the toughness is decreased in the welded portion and the heat affected zone.
Ｃｅｑ＝Ｃ＋１／２４×Ｓｉ＋１／６×Ｍｎ（％）・・・（ア）
高強度鋼板を使用する際に溶接継手強度を確保するためには、溶接法の観点からは、打点数の増加やナゲット径の拡大が考えられる。しかし、打点数の増加はスペースが必要であり、作業時間の増加につながり生産性を悪化させる。また、ナゲット径ｄを拡大するには電極を大きくしたり、溶接金属の飛散（散り、チリ）を防ぐために加圧力を増加しなければならず、装置的な制約も受けるほか、熱影響部が拡大するため溶接継手部および近傍の母材特性が損なわれる欠点もある。
Ceq = C + 1/24 × Si + 1/6 × Mn (%) (a)
In order to ensure the strength of the welded joint when using a high-strength steel plate, from the viewpoint of the welding method, an increase in the number of hitting points and an increase in the nugget diameter are conceivable. However, an increase in the number of hit points requires a space, which leads to an increase in work time and deteriorates productivity. In order to increase the nugget diameter d, the electrode must be enlarged or the applied pressure must be increased to prevent the weld metal from scattering (scattering, dust). Since it expands, there is also a drawback that the properties of the base material in the welded joint and the vicinity are impaired.
そこで、抵抗スポット溶接時、従来と同様、あるいはそれ以下の打点数およびナゲット径で強度を確保するために、ナゲットを形成する本通電の後に通電を行う後熱通電方式に対して様々な試みがなされてきた。そのうち、一度溶接部を凝固、変態させた後に再加熱することにより、ナゲットおよびＨＡＺ部分を軟化させることで、ナゲットの靭性向上や溶接部近傍の応力集中緩和をはかり、継手強度向上を実現する方法が多く検討されてきた。 Therefore, during resistance spot welding, various attempts have been made for the post-heat energization method in which energization is performed after the main energization for forming the nugget in order to ensure the strength with the number of striking points and the nugget diameter that is the same as or less than that in the prior art. Has been made. Among them, once the weld is solidified and transformed, it is reheated to soften the nugget and the HAZ part, thereby improving the toughness of the nugget and reducing the stress concentration near the weld and improving the joint strength. Has been studied a lot.
その一例として特許文献１では、テンパー通電における通電時間Ｔｔ・通電電流Ｉｔと本通電における通電時間Ｔo・通電電流Ｉoを用いて、（Ｉｔ／Ｉo）の二乗と（Ｔｔ／Ｔｏ）の積が０．２５〜０．８２の範囲に入っている事が望ましいとしている。 As an example, in Patent Document 1, the product of the square of (It / Io) and (Tt / To) is 0 using the energization time Tt and energization current It in temper energization and the energization time To and energization current Io in main energization. It is desirable to be in the range of 25-0.82.
特許文献２では、溶接後保持時間HTを、板厚tを用いて下記（イ）式
300−500ｔ＋250ｔ２≦ ＨＴ ≦ 560−900ｔ＋500ｔ２・・・（イ）
で表す範囲にし、また、後熱通電を後通電電流を溶接通電電流の７０％以上９０％以下の範囲とし、後通電時間を溶接通電時間の６０％以上１００％以下の範囲に規定することで溶接部の冷却中の温度降下速度を調整することにより引張強さを向上させることができることが開示されている。
In
300−500t + 250t 2 ≦ HT ≦ 560−900t + 500t 2 (B)
In addition, the post-heat energization is set in a range of 70% to 90% of the welding energization current, and the post-energization time is defined in the range of 60% to 100% of the welding energization time. It is disclosed that the tensile strength can be improved by adjusting the temperature drop rate during cooling of the weld.
また、特許文献３には、冷却と通電を繰り返すことによって短時間にて焼戻しの効果が得られることが開示されている。 Patent Document 3 discloses that tempering effects can be obtained in a short time by repeating cooling and energization.
しかしながら、前記特許文献１および２に記載されているような通電方法は、本通電以下の電流値で、十分な抵抗発熱が可能な範囲を選ぶことが必要となるために、利用可能な電流範囲は狭く、わずかな電流値・電流時間の変化で抵抗発熱に大きく影響を及ぼすため、実施する上でその適用範囲が狭い。
However, the energization methods as described in
さらに、特許文献３に記載されているような通電方法は、後熱通電を含め全ての通電が同じ条件であるがために、高張力鋼板において最適な条件とはいいがたく、また、特許文献１および２と同様、溶接条件等の適正化には多くの検討課題がある。 Furthermore, since the energization method as described in Patent Document 3 has the same conditions for all energization including post-heat energization, it is difficult to say that the optimum conditions for a high-tensile steel sheet. As in 1 and 2, there are many issues to be investigated in optimizing welding conditions and the like.
本発明は、高強度鋼板を含む板組の抵抗スポット溶接において、前記問題を解決し、条件決定のし易さ、適用範囲の適正化と、溶接時間の短縮を同時に達成し、高い継手強度を実現する抵抗スポット溶接方法を提供することを目的とする。 The present invention solves the above-mentioned problems in resistance spot welding of a plate assembly including a high-strength steel plate, and at the same time, achieves easy determination of conditions, optimization of application range, and shortening of welding time, and high joint strength. It aims at providing the resistance spot welding method implement | achieved.
本発明者らは、前記課題を解決するために、継手強度とナゲット組織、プロセス温度、電流密度の関係を詳細に検討した。その結果、以下の知見を得た。なお、以下の式において図２に示すように、第1ステップの本通電を通電電流IA（kA）、通電時間TA（ｍｓ）、さらに後熱通電である第2ステップの無通電で保持する時間を保持時間Th（ｍｓ）、その後、通電している時間および電流をそれぞれ通電時間TB（ｍｓ）、通電電流IB（kA）とした。なお、図２では、交流電源を例に取っているため、電流波形のRMS値（実効電流値）を電流値としている。 In order to solve the above problems, the present inventors have studied in detail the relationship between joint strength, nugget structure, process temperature, and current density. As a result, the following knowledge was obtained. In the following equation, as shown in FIG. 2, the main energization of the first step is held for the energization current IA (kA), the energization time TA (ms), and further the non-energization of the second step, which is the post-heat energization. Was the holding time Th (ms), and the energization time and current were energized time TB (ms) and energized current IB (kA), respectively. In FIG. 2, since an AC power supply is taken as an example, the RMS value (effective current value) of the current waveform is used as the current value.
まず、本発明者らは、発熱の指標となる電流二乗時間積（I2×時間）に着目し、後通電に対する本通電の電流二乗時間積の比が下記（１）式の関係にあることが必要であることを見出した。 First, the present inventors pay attention to the current square time product (I 2 × time), which is an index of heat generation, and the ratio of the current square time product of main energization to post energization is in the relationship of the following equation (1). Found that is necessary.
０．０５＜（ＩＢ２×ＴＢ）／（ＩＡ２×ＴＡ）＜１．０・・・（１）
（１）式は本通電に対する後通電の発熱量を立式化したものである。この式の上限の設定は、不必要な入熱を抑制し、継手強度を高めると同時に施工性を向上する観点から定めた。下限値は効果を得るための最小限の加熱を得る観点から定めた。
0.05 <(IB 2 × TB) / (IA 2 × TA) <1.0 (1)
Equation (1) formulates the calorific value of post-energization relative to main energization. The upper limit of this formula was determined from the viewpoint of suppressing unnecessary heat input, increasing joint strength, and simultaneously improving workability. The lower limit was determined from the viewpoint of obtaining the minimum heating for obtaining the effect.
また、通電時間ＴＢ（ｍｓ）は下記（２）式の関係にあることが必要である。 Further, the energization time TB (ms) needs to have the relationship of the following equation (2).
２０≦ＴＢ≦１００・・・（２）
この（２）式は、施工上の観点から（１）式を制限するものである。
20 ≦ TB ≦ 100 (2)
This formula (2) limits the formula (1) from the viewpoint of construction.
さらに、保持時間Ｔｈ（ｍｓ）は下記（３）式の関係にあることが必要である。ここで、ナゲットの径であるナゲット径ｄ（ｍｍ）、電極の先端部面積Ｓ（ｍｍ２）、総板厚ｔ（ｍｍ）とした。 Furthermore, the holding time Th (ms) needs to be in the relationship of the following equation (3). Here, the nugget diameter d (mm), which is the diameter of the nugget, the tip end area S (mm 2 ), and the total plate thickness t (mm) were used.
１０×（ｔ×ｄ２）／Ｓ＜Ｔｈ＜２００×（ｔ×ｄ２）／Ｓ・・・ （３）
本（３）式は、冷却速度を遅くするファクタとしてナゲットの持つ熱量をナゲット径ｄ（ｍｍ）とし、速くするファクタとして電極の先端部面積Ｓ（ｍｍ２）を，総板厚ｔ（ｍｍ）で立式化したものである。
10 × (t × d 2 ) / S <Th <200 × (t × d 2 ) / S (3)
In this equation (3), the nugget has a nugget diameter d (mm) as a factor for reducing the cooling rate, and the tip end area S (mm 2 ) as a factor for increasing the total thickness t (mm). It was formulated in
さらに、第２ステップの後に再度電極で加圧したまま無通電で保持して溶接部を冷却することにより、次に続く通電での過度の高温化を抑制できることも知見した。この時の条件として、一回目の保持時間で溶接部の冷却は進んでいるわけであるから、二回目の保持時間は一回目よりも短く、次に続く通電も一回目と同等か、それよりも高い必要がある。 Further, it has also been found that, after the second step, an excessive increase in temperature due to the subsequent energization can be suppressed by holding the non-energized state while being pressurized with the electrode again and cooling the weld. As a condition at this time, since the cooling of the weld progresses in the first holding time, the second holding time is shorter than the first time, and the energization that follows is equal to the first time, or more Also need to be expensive.
したがって、本発明は、下記を構成要件としている。
[１]二枚以上の鋼板を重ね合せた総板厚ｔ（ｍｍ）の板組を、一対の溶接電極で挟持し、加圧しながら通電して溶接する抵抗スポット溶接方法であって、
ナゲットを形成する第１ステップと、
電極で加圧したまま、無通電で保持することにより溶接部を冷却した後通電する第２ステップとを備え、
前記第１ステップにおける通電時間ＴＡ（ｍｓ）、通電電流ＩＡ（ｋＡ）、第２ステップにおける通電時間ＴＢ（ｍｓ）、通電電流ＩＢ（ｋＡ）が、
（１）及び（２）式を満足し、
前記第２ステップの無通電の保持時間Ｔｈ（ｍｓ）が、板組の総板厚ｔ（ｍｍ）、前記ナゲットの径ｄ（ｍｍ）、前記溶接電極の先端部面積Ｓ（ｍｍ２）との関係で、
（３）式を満足すること、
を特徴とする抵抗スポット溶接方法。
Therefore, the present invention has the following constituent elements.
[1] A resistance spot welding method in which a plate assembly having a total plate thickness t (mm) obtained by superposing two or more steel plates is sandwiched between a pair of welding electrodes and energized while being pressurized and welded.
A first step of forming a nugget;
A second step of energizing after cooling the weld by holding the electrode without applying electricity while being pressurized with an electrode,
The energization time TA (ms), the energization current IA (kA) in the first step, the energization time TB (ms), the energization current IB (kA) in the second step,
Satisfies (1) and (2),
The non-energized holding time Th (ms) in the second step is the total plate thickness t (mm) of the plate assembly, the diameter n (mm) of the nugget, and the tip end area S (mm 2 ) of the welding electrode. In relation
(3) satisfying the equation,
A resistance spot welding method characterized by:
０．０５＜（ＩＢ２×ＴＢ）／（ＩＡ２×ＴＡ）＜１．０・・・（１）
２０≦ＴＢ≦１００・・・（２）
１０×（ｔ×ｄ２）／Ｓ＜Ｔｈ＜２００×（ｔ×ｄ２）／Ｓ・・・（３）
[２]前記第２ステップの後、さらに、電極で加圧したまま無通電で保持することにより溶接部を冷却し、その後、通電する第３ステップを備え、
該第３ステップにおける無通電で保持する保持時間Ｔｈｃ（ｍｓ）、その後の通電の通電電流値ＩＣ（ｋＡ）及び通電時間ＴＣ（ｍｓ）が下記（４）〜（６）式を満足することを特徴とする［１]に記載の抵抗スポット溶接方法。
0.05 <(IB 2 × TB) / (IA 2 × TA) <1.0 (1)
20 ≦ TB ≦ 100 (2)
10 × (t × d 2 ) / S <Th <200 × (t × d 2 ) / S (3)
[2] After the second step, further comprising a third step of cooling the welded portion by holding it without being energized while being pressurized with an electrode, and then energizing,
The holding time Thc (ms) held in the third step without energization, the energization current value IC (kA) for energization thereafter, and the energization time TC (ms) satisfy the following expressions (4) to (6). The resistance spot welding method according to [1], which is characterized.
１０＜Ｔｈｃ＜Ｔｈ・・・（４）
１．０≦（ＩＣ２×ＴＣ）／（ＩＢ２×ＴＢ）≦３．０・・・（５）
２０≦ＴＣ≦１００・・・（６）
［３]前記第３ステップの後、さらに、電極で加圧したまま無通電で保持することにより溶接部を冷却し、その後、通電するステップを複数備えることを特徴とする［２]に記載の抵抗スポット溶接方法。
10 <Thc <Th (4)
1.0 ≦ (IC 2 × TC) / (IB 2 × TB) ≦ 3.0 (5)
20 ≦ TC ≦ 100 (6)
[3] The method according to [2], further comprising a plurality of steps of cooling the welded portion by holding the electrode without being energized while being pressurized with the electrode after the third step, and then energizing. Resistance spot welding method.
本発明によれば、ナゲットを形成する本通電の後に加圧を維持したまま無通電で冷却する保持時間と、その後の通電時間から成る後熱通電を負荷する通電パターンにおいて、本通電の通電時間、電流値、保持時間、後熱通電の通電時間および電流値を整理したことで、条件決定までの工程を短縮し、かつ、高強度の継手強度が得られる。また、後熱通電においては、電流値を本通電よりも高く設定し、通電時間は保持時間よりも短く設定することを要件としたことから、条件範囲を広く設定することができるとともに、溶接時間を短縮することができる。 According to the present invention, the energization time of the main energization in the energization pattern in which the post-heat energization comprising the energization time and the holding time for cooling without energization while maintaining the pressurization after the main energization to form the nugget is performed. By arranging the current value, holding time, energization time of post-heat energization, and current value, the process up to the condition determination can be shortened and a high strength joint strength can be obtained. In post-heat energization, the current value is set higher than the main energization, and the energization time is set shorter than the holding time. Therefore, the condition range can be set wide and the welding time can be set. Can be shortened.
本発明は、まず、二枚以上の鋼板を重ね合せた総板厚ｔ（ｍｍ）の板組を、一対の溶接電極で挟持し、加圧しながら通電して溶接する抵抗スポット溶接方法である。このような抵抗スポット溶接方法が産業界で広く使用されているからである。本発明で高強度鋼板とは５９０〜１９６０ＭＰａの強度を有する鋼板を対象とする。 The present invention is a resistance spot welding method in which a plate set having a total thickness t (mm) obtained by superimposing two or more steel plates is sandwiched between a pair of welding electrodes and is energized and welded while being pressed. This is because such a resistance spot welding method is widely used in industry. In the present invention, the high strength steel plate is intended for a steel plate having a strength of 590 to 1960 MPa.
本発明の第１ステップでは、ナゲットを形成する。このときの通電を本電流と呼ぶ場合がある。第１ステップにおける通電時間をＴＡ（ｍｓ）とし、通電電流をＩＡ（ｋＡ）を記号化する。 In the first step of the present invention, a nugget is formed. The energization at this time may be referred to as a main current. The energization time in the first step is TA (ms), and the energization current is symbolized as IA (kA).
つぎの、電極で加圧したまま、無通電で保持することにより溶接部を冷却した後通電する第２ステップでは、冷却を主たる目的とする。第２ステップの無通電の保持時間Ｔｈ（ｍｓ）においては電極で加圧したままとする。加圧力は１．５ｋＮ以上１０ｋN以下の範囲が好ましい。 In the second step in which the weld is cooled and then energized while being pressurized with the electrodes while being pressurized, the main purpose is cooling. In the second step, the non-energized holding time Th (ms), the electrode is kept pressurized. The applied pressure is preferably in the range of 1.5 kN to 10 kN.
第２ステップにおいては無通電で保持した後、通電時間ＴＢ（ｍｓ）、通電電流ＩＢ（ｋＡ）が、本通電の通電時間、通電電流の関係において（１）及び（２）式を満足することが必要である。 In the second step, after holding without energization, the energization time TB (ms) and the energization current IB (kA) satisfy the formulas (1) and (2) in relation to the energization time and energization current of the main energization. is necessary.
さらには、板組の総板厚ｔ（ｍｍ）、前記ナゲットの径ｄ（ｍｍ）、前記溶接電極の先端部面積Ｓ（ｍｍ２）との関係で、
（３）式を満足することが必要である。
Furthermore, in relation to the total thickness t (mm) of the plate assembly, the diameter d (mm) of the nugget, and the tip end area S (mm 2 ) of the welding electrode,
It is necessary to satisfy the formula (3).
０．０５＜（ＩＢ２×ＴＢ）／（ＩＡ２×ＴＡ）＜１．０・・・（１）
２０≦ＴＢ≦１００・・・（２）
１０×（ｔ×ｄ２）／Ｓ＜Ｔｈ＜２００×（ｔ×ｄ２）／Ｓ・・・（３）
（１）式の技術的意義は前述したように、不必要な入熱を抑制し、継手強度を高めると同時に施工性を向上する観点から立式化したものである。入熱量が過小もしくは過大となることを避けるため、さらに好ましくは
０．４≦（ＩＢ２×ＴＢ）／（ＩＡ２×ＴＡ）＜１．０である。
0.05 <(IB 2 × TB) / (IA 2 × TA) <1.0 (1)
20 ≦ TB ≦ 100 (2)
10 × (t × d 2 ) / S <Th <200 × (t × d 2 ) / S (3)
As described above, the technical significance of the formula (1) is formulated from the viewpoint of suppressing unnecessary heat input, increasing joint strength, and simultaneously improving workability. More preferably, 0.4 ≦ (IB 2 × TB) / (IA 2 × TA) <1.0 in order to avoid an excessive or excessive heat input.
（２）式の通電時間ＴＢが２０未満であれば入熱量が過小となり、
１００を超えると入熱量が過大となり溶接部の機械的特性が劣化するので、上記の範囲とした。さらに、好ましくは４０≦ＴＢ≦８０である。
If the energization time TB of the formula (2) is less than 20, the heat input becomes excessive,
If it exceeds 100, the amount of heat input becomes excessive and the mechanical properties of the welded portion deteriorate, so the above range was adopted. Further, preferably 40 ≦ TB ≦ 80.
また、（３）式において第２ステップの無通電の保持時間Ｔｈ（ｍｓ）が１０×（ｔ×ｄ２）／Ｓを超えるようにしなければならないのは、溶接部の冷却状態が不完全となるのを防止するためである。溶接部端部（溶融部と熱影響部の境界，ヒュージョンライン）の冷却温度は少なくとも１３００℃以下にすることが好ましい。また、無通電の保持時間Ｔｈ（ｍｓ）は、２００×（ｔ×ｄ２）／Ｓ未満とするのは、溶接部が冷却過剰となるのを防止するためである。溶接部端部の温度はＡｃ１温度以上にすることが好ましい。
また、確実に溶接部の温度を制御するためには、
２０×（ｔ×ｄ２）／Ｓ＜Ｔｈ＜１００×（ｔ×ｄ２）／Ｓ
とすることがさらに好ましい。
Further, in the equation (3), the non-energized holding time Th (ms) in the second step must exceed 10 × (t × d 2 ) / S because the welded state is incompletely cooled. This is to prevent this from happening. The cooling temperature of the weld end (the boundary between the melted part and the heat affected zone, the fusion line) is preferably at least 1300 ° C. or less. The reason why the non-energized holding time Th (ms) is less than 200 × (t × d 2 ) / S is to prevent the welded portion from being overcooled. The temperature at the end of the welded portion is preferably set to Ac 1 temperature or higher.
In addition, in order to control the temperature of the welded part reliably,
20 × (t × d 2 ) / S <Th <100 × (t × d 2 ) / S
More preferably.
さらに、第２ステップの後、電極で加圧したまま無通電で保持することにより溶接部を冷却し、その後、通電する第３ステップを備えることが好ましい。
この第３ステップを採用する場合は、無通電で保持する保持時間Ｔｈｃ（ｍｓ）、その後の通電の通電電流値ＩＣ（ｋＡ）及び通電時間ＴＣ（ｍｓ）が下記（４）〜（６）式を満足することが必要である。
Furthermore, after the second step, it is preferable to include a third step of cooling the welded portion by holding the electrode without applying electricity while being pressurized with an electrode, and then energizing.
When this third step is adopted, the holding time Thc (ms) that is held without energization, the energization current value IC (kA) and energization time TC (ms) of energization thereafter are expressed by the following equations (4) to (6). It is necessary to satisfy
１０＜Ｔｈｃ＜Ｔｈ・・・（４）
１．０≦（ＩＣ２×ＴＣ）／（ＩＢ２×ＴＢ）≦３．０・・・（５）
２０≦ＴＣ≦１００・・・（６）
一回目の保持時間で溶接部の冷却は進んでいるわけであるから、二回目の保持時間は一回目よりも短く、次に続く通電も一回目と同等か、それよりも高い必要がある。
10 <Thc <Th (4)
1.0 ≦ (IC 2 × TC) / (IB 2 × TB) ≦ 3.0 (5)
20 ≦ TC ≦ 100 (6)
Since the weld is being cooled in the first holding time, the second holding time is shorter than the first time, and the subsequent energization needs to be equal to or higher than the first time.
さらに、３回目の通電による過剰入熱を避けるため、
１．０≦（ＩＣ２×ＴＣ）／（ＩＢ２×ＴＢ）≦２．０
とすることが好ましい。
Furthermore, in order to avoid excessive heat input due to the third energization,
1.0 ≦ (IC 2 × TC) / (IB 2 × TB) ≦ 2.0
It is preferable that
なお、この第３ステップに関して、テンパーの効果が得られない際には冷却−通電を２回以上繰り返すことで確実に得ることが出来る場合があり、第３ステップの後、さらに、電極で加圧したまま無通電で保持することにより溶接部を冷却し、その後、通電するステップを複数行うこともできる。この場合、第４ステップの条件は第３ステップの条件との関係を考慮して第３ステップに準じて行うことが好ましい。すなわち、さらに複数回行う場合には第Ｎステップの条件は第（Ｎ−１）ステップとの関係を考慮して決定することが好ましい。 In addition, regarding the third step, when the effect of the temper is not obtained, it may be possible to reliably obtain the tempering by repeating cooling and energization twice or more. After the third step, further pressurization with the electrode It is also possible to cool the welded part by holding it without energization, and then perform a plurality of energization steps. In this case, it is preferable that the condition of the fourth step is performed according to the third step in consideration of the relationship with the condition of the third step. That is, in the case of performing a plurality of times, it is preferable to determine the condition of the Nth step in consideration of the relationship with the (N-1) th step.
本発明の実施例１として、前述の図１に示したように、２枚の鋼板（下の鋼板１、上の鋼板２）を重ねた板組３について、溶接ガンに取付けられたサーボモータ加圧式で単相交流（５０Ｈｚ）の抵抗溶接機を用いて抵抗スポット溶接を行い、抵抗スポット溶接継手を作製した。なお、使用した一対の電極チップ（下の電極チップ４、上の電極チップ５）は、ともに図３に示すように、先端の曲率半径Ｒ４０ｍｍ、先端径６ｍｍを有するアルミナ分散銅のＤＲ型電極とした。 As Example 1 of the present invention, as shown in FIG. 1 described above, a servomotor attached to a welding gun is added to a plate set 3 in which two steel plates (lower steel plate 1 and upper steel plate 2) are stacked. Resistance spot welding was performed by using a pressure single-phase alternating current (50 Hz) resistance welder to produce a resistance spot welded joint. As shown in FIG. 3, the pair of electrode tips used (lower electrode tip 4 and upper electrode tip 5) are composed of an alumina-dispersed copper DR type electrode having a tip radius of curvature R of 40 mm and a tip diameter of 6 mm. did.
試験片として、鋼板１、２ともに、板厚１．６ｍｍの１１８０ＭＰａ級二相組織裸鋼板を使用した。ＪＩＳ Ｚ３１３７に基づき溶接および引張試験を行った。スクイズ時間あるいはスロープ時間については特に設定しなかった。
As the test pieces, 1180 MPa class two-phase bare steel plates having a plate thickness of 1.6 mm were used for both the
そして、本発明例として、上記の本発明の一実施形態に基づいて抵抗スポット溶接を行った。その際の通電パターンを、図２（ａ）に示す。第１ステップとして電流値ＩＡをＴＡの間通電し、ナゲットを形成した後、第２ステップ、第３ステップの通電をそれぞれ行った。通電終了後ガンが開き加圧力が０になるまでの保持時間は１サイクルに設定した。 And as an example of this invention, resistance spot welding was performed based on one Embodiment of said this invention. An energization pattern at that time is shown in FIG. As a first step, the current value IA was energized during TA to form a nugget, and then energized in the second step and the third step, respectively. The holding time until the gun was opened after the end of energization and the pressure became zero was set to one cycle.
一方、比較例（１）として、本通電のみで後熱通電を行わない抵抗スポット溶接、比較例（２）として一般的なテンパー通電を行った。 On the other hand, as comparative example (1), resistance spot welding with only post-energization and no post-heat energization was performed, and general temper energization was performed as comparative example (2).
表１に、本発明例および各比較例の溶接条件と溶接結果を示す。まず、条件式に適合するかを評価し、適合した場合を○、適合しない場合を×とした。次に、継手強度の観点から、十字引張強度（ＣＴＳ、JISZ３１３７に記載される十字引張試験を行った際の破断荷重）を比較例（１）と比較し、1kN以上上回った場合を○、増加が1kN未満であった場合を△、下回った場合を×とした。なお、請求項１に基づく実施例は１、４、７、１０、１３、１６である．さらに、本通電終了後から最後の通電が終了するまでの時間が、比較例（２）と比較して、1/2未満に短縮された場合を◎、1/2以上であるが短縮されたものを○とした。本発明例においては、比較例（１）に比べて、十字引張強度の向上が認められた。 Table 1 shows welding conditions and welding results of the inventive examples and the comparative examples. First, whether or not the conditional expression is satisfied was evaluated. Next, from the viewpoint of joint strength, the cross tensile strength (CTS, breaking load when performing the cross tensile test described in JISZ3137) is compared with Comparative Example (1). Was less than 1 kN, and x was less than x. In addition, the Example based on Claim 1 is 1, 4, 7, 10, 13, 16. Furthermore, when the time from the end of the main energization to the end of the last energization is shortened to less than 1/2 compared with the comparative example (2), it is ◎, but more than 1/2 but has been shortened. The thing was made into (circle). In the example of the present invention, an improvement in the cross tensile strength was recognized as compared with Comparative Example (1).
本発明の実施例２として、前述の図１に示したように、２枚の鋼板（下の鋼板１、上の鋼板２）を重ねた板組３について、溶接ガンに取付けられたサーボモータ加圧式で単相交流（５０Ｈｚ）の抵抗溶接機を用いて抵抗スポット溶接を行い、抵抗スポット溶接継手を作製した。なお、使用した一対の電極チップ（下の電極チップ４、上の電極チップ５）は、ともに図３に示すように、先端の曲率半径Ｒ４０ｍｍ、先端径６ｍｍを有するアルミナ分散銅のＤＲ型電極とした。 As Example 2 of the present invention, as shown in FIG. 1 described above, a servomotor attached to a welding gun is added to a plate set 3 in which two steel plates (lower steel plate 1 and upper steel plate 2) are stacked. Resistance spot welding was performed by using a pressure single-phase alternating current (50 Hz) resistance welder to produce a resistance spot welded joint. As shown in FIG. 3, the pair of electrode tips used (lower electrode tip 4 and upper electrode tip 5) are composed of an alumina-dispersed copper DR type electrode having a tip radius of curvature R of 40 mm and a tip diameter of 6 mm. did.
試験片として、鋼板１、２ともに、板厚１．６ｍｍの１１８０ＭＰａ級二相組織裸鋼板を使用した。ＪＩＳ Ｚ３１３７に基づき溶接および引張試験を行った。スクイズ時間あるいはスロープ時間については特に設定しなかった。
As the test pieces, 1180 MPa class two-phase bare steel plates having a plate thickness of 1.6 mm were used for both the
そして、本発明例として、上記の本発明の一実施形態に基づいて抵抗スポット溶接を行った。その際の通電パターンを、図２（ｂ）に示す。第１ステップとして電流値ＩＡをＴＡの間通電し、ナゲットを形成した後、第２ステップ、複数回の第３ステップの通電をそれぞれ行った。通電終了後ガンが開き加圧力が０になるまでの保持時間は１サイクルに設定した。 And as an example of this invention, resistance spot welding was performed based on one Embodiment of said this invention. The energization pattern at that time is shown in FIG. As a first step, the current value IA was energized during TA to form a nugget, and then the second step and a plurality of third steps were energized. The holding time until the gun was opened after the end of energization and the pressure became zero was set to one cycle.
一方、比較例（１）として、本通電のみで後熱通電を行わない抵抗スポット溶接、比較例（２）として一般的なテンパー通電を行った。 On the other hand, as comparative example (1), resistance spot welding with only post-energization and no post-heat energization was performed, and general temper energization was performed as comparative example (2).
表２に、本発明例および各比較例の溶接条件と溶接結果を示す。まず、条件式に適合するかを評価し、適合した場合を○、適合しない場合を×とした。次に、継手強度の観点から、十字引張強度（ＣＴＳ、JISZ３１３７に記載される十字引張試験を行った際の破断荷重）を比較例（１）と比較し、1kN以上上回った場合を○、増加が1kN未満であった場合を△、下回った場合を×とした。さらに、本通電終了後から最後の通電が終了するまでの時間が、比較例（２）と比較して、1/2未満に短縮された場合を◎、1/2以上であるが短縮されたものを○とした。本発明例においては、比較例（１）に比べて、十字引張強度の向上が認められた。 Table 2 shows welding conditions and welding results of the inventive examples and the comparative examples. First, whether or not the conditional expression is satisfied was evaluated. Next, from the viewpoint of joint strength, the cross tensile strength (CTS, breaking load when performing the cross tensile test described in JISZ3137) is compared with Comparative Example (1). Was less than 1 kN, and x was less than x. Furthermore, when the time from the end of the main energization to the end of the last energization is shortened to less than 1/2 compared with the comparative example (2), it is ◎, but more than 1/2 but has been shortened. The thing was made into (circle). In the example of the present invention, an improvement in the cross tensile strength was recognized as compared with Comparative Example (1).
１ 下の鋼板
２ 上の鋼板
３ 板組
４ 下の電極チップ
５ 上の電極チップ
６ ナゲット
ｔ 総板厚（ｍｍ）
ｄ ナゲット径
DESCRIPTION OF SYMBOLS 1
d Nugget diameter
Claims (3)
ナゲットを形成する第１ステップと、
電極で加圧したまま、無通電で保持することにより溶接部を冷却した後、通電する第２ステップとを備え、
前記第１ステップにおける通電時間ＴＡ（ｍｓ）、通電電流ＩＡ（ｋＡ）、第２ステップにおける通電時間ＴＢ（ｍｓ）、通電電流ＩＢ（ｋＡ）が、
（１）及び（２）式を満足し、
前記第２ステップの無通電の保持時間Ｔｈ（ｍｓ）が、板組の総板厚ｔ（ｍｍ）、前記ナゲットの径ｄ（ｍｍ）、前記溶接電極の先端部面積Ｓ（ｍｍ２）との関係で、
（３）式を満足すること、
を特徴とする抵抗スポット溶接方法。
０．０５＜（ＩＢ２×ＴＢ）／（ＩＡ２×ＴＡ）＜１．０・・・（１）
２０≦ＴＢ≦１００・・・（２）
１０×（ｔ×ｄ２）／Ｓ＜Ｔｈ＜２００×（ｔ×ｄ２）／Ｓ・・・（３） It is a resistance spot welding method in which a plate assembly having a total thickness t (mm) obtained by superimposing two or more steel plates is sandwiched between a pair of welding electrodes and is energized while being pressurized and welded.
A first step of forming a nugget;
A second step of energizing after cooling the weld by holding the electrode without applying electricity while being pressurized with an electrode,
The energization time TA (ms), the energization current IA (kA) in the first step, the energization time TB (ms), the energization current IB (kA) in the second step,
Satisfies (1) and (2),
The non-energized holding time Th (ms) in the second step is the total plate thickness t (mm) of the plate assembly, the diameter n (mm) of the nugget, and the tip end area S (mm 2 ) of the welding electrode. In relation
(3) satisfying the equation,
A resistance spot welding method characterized by:
0.05 <(IB 2 × TB) / (IA 2 × TA) <1.0 (1)
20 ≦ TB ≦ 100 (2)
10 × (t × d 2 ) / S <Th <200 × (t × d 2 ) / S (3)
該第３ステップにおける無通電で保持する保持時間Ｔｈｃ（ｍｓ）、その後の通電の通電電流値ＩＣ（ｋＡ）及び通電時間ＴＣ（ｍｓ）が下記（４）〜（６）式を満足することを特徴とする請求項１に記載の抵抗スポット溶接方法。
１０＜Ｔｈｃ＜Ｔｈ・・・（４）
１．０≦（ＩＣ２×ＴＣ）／（ＩＢ２×ＴＢ）≦３．０・・・（５）
２０≦ＴＣ≦１００・・・（６） After the second step, further comprising a third step of cooling the welded portion by holding it without being energized while being pressurized with an electrode, and then energizing,
The holding time Thc (ms) held in the third step without energization, the energization current value IC (kA) for energization thereafter, and the energization time TC (ms) satisfy the following expressions (4) to (6). The resistance spot welding method according to claim 1, wherein:
10 <Thc <Th (4)
1.0 ≦ (IC 2 × TC) / (IB 2 × TB) ≦ 3.0 (5)
20 ≦ TC ≦ 100 (6)
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20140367368A1 (en) * | 2013-06-14 | 2014-12-18 | GM Global Technology Operations LLC | Resistance spot welding thin gauge steels |
| WO2018181231A1 (en) * | 2017-03-31 | 2018-10-04 | Ｊｆｅスチール株式会社 | Production method for resistance spot welded joint |
| WO2020050011A1 (en) * | 2018-09-05 | 2020-03-12 | 本田技研工業株式会社 | Spot welding method |
| JP2020040122A (en) * | 2018-09-07 | 2020-03-19 | Ｊｆｅスチール株式会社 | Resistance spot welding method and manufacturing method of resistance spot welded joint |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS583792A (en) * | 1981-06-29 | 1983-01-10 | Kawasaki Steel Corp | Spot welding method of high tension steel plate |
| JP2011067853A (en) * | 2009-09-28 | 2011-04-07 | Nippon Steel Corp | Spot welding method for high-strength steel sheet |
-
2011
- 2011-11-25 JP JP2011257006A patent/JP5891741B2/en active Active
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS583792A (en) * | 1981-06-29 | 1983-01-10 | Kawasaki Steel Corp | Spot welding method of high tension steel plate |
| JP2011067853A (en) * | 2009-09-28 | 2011-04-07 | Nippon Steel Corp | Spot welding method for high-strength steel sheet |
Cited By (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20140367368A1 (en) * | 2013-06-14 | 2014-12-18 | GM Global Technology Operations LLC | Resistance spot welding thin gauge steels |
| CN104227211A (en) * | 2013-06-14 | 2014-12-24 | 通用汽车环球科技运作有限责任公司 | Resistance spot welding thin-gauge steel |
| US9737956B2 (en) * | 2013-06-14 | 2017-08-22 | GM Global Technology Operations LLC | Resistance spot welding thin gauge steels |
| CN110461528A (en) * | 2017-03-31 | 2019-11-15 | 杰富意钢铁株式会社 | The manufacturing method of joint for resistance spot welding |
| JP6410003B1 (en) * | 2017-03-31 | 2018-10-24 | Ｊｆｅスチール株式会社 | Method of manufacturing resistance spot welded joint |
| KR20190126098A (en) * | 2017-03-31 | 2019-11-08 | 제이에프이 스틸 가부시키가이샤 | Method of manufacturing resistance spot welded joints |
| WO2018181231A1 (en) * | 2017-03-31 | 2018-10-04 | Ｊｆｅスチール株式会社 | Production method for resistance spot welded joint |
| KR102225221B1 (en) | 2017-03-31 | 2021-03-08 | 제이에프이 스틸 가부시키가이샤 | Method of manufacturing resistance spot welded joints |
| WO2020050011A1 (en) * | 2018-09-05 | 2020-03-12 | 本田技研工業株式会社 | Spot welding method |
| CN112654454A (en) * | 2018-09-05 | 2021-04-13 | 本田技研工业株式会社 | Spot welding method |
| JPWO2020050011A1 (en) * | 2018-09-05 | 2021-08-26 | 本田技研工業株式会社 | Spot welding method |
| JP7094374B2 (en) | 2018-09-05 | 2022-07-01 | 本田技研工業株式会社 | Spot welding method |
| JP2020040122A (en) * | 2018-09-07 | 2020-03-19 | Ｊｆｅスチール株式会社 | Resistance spot welding method and manufacturing method of resistance spot welded joint |
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