JPWO2020045678A1 - Resistance spot welding method - Google Patents
Resistance spot welding method Download PDFInfo
- Publication number
- JPWO2020045678A1 JPWO2020045678A1 JP2020539656A JP2020539656A JPWO2020045678A1 JP WO2020045678 A1 JPWO2020045678 A1 JP WO2020045678A1 JP 2020539656 A JP2020539656 A JP 2020539656A JP 2020539656 A JP2020539656 A JP 2020539656A JP WO2020045678 A1 JPWO2020045678 A1 JP WO2020045678A1
- Authority
- JP
- Japan
- Prior art keywords
- energization
- time
- current
- welding
- dust
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000003466 welding Methods 0.000 title claims abstract description 54
- 238000000034 method Methods 0.000 title claims abstract description 25
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 65
- 239000010959 steel Substances 0.000 claims abstract description 65
- 230000010349 pulsation Effects 0.000 claims abstract description 15
- 239000000428 dust Substances 0.000 description 28
- 238000007747 plating Methods 0.000 description 8
- 239000010410 layer Substances 0.000 description 7
- 238000003825 pressing Methods 0.000 description 6
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 4
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 description 4
- 229910052782 aluminium Inorganic materials 0.000 description 4
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 4
- 229910052725 zinc Inorganic materials 0.000 description 4
- 239000011701 zinc Substances 0.000 description 4
- 230000008602 contraction Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 230000020169 heat generation Effects 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 238000000465 moulding Methods 0.000 description 2
- 230000004044 response Effects 0.000 description 2
- 239000011787 zinc oxide Substances 0.000 description 2
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229910001335 Galvanized steel Inorganic materials 0.000 description 1
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical group [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 238000005275 alloying Methods 0.000 description 1
- 229910001566 austenite Inorganic materials 0.000 description 1
- 239000010953 base metal Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 239000008397 galvanized steel Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 229910000765 intermetallic Inorganic materials 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
- 238000004381 surface treatment Methods 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
Images
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K11/00—Resistance welding; Severing by resistance heating
- B23K11/10—Spot welding; Stitch welding
- B23K11/11—Spot welding
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K11/00—Resistance welding; Severing by resistance heating
- B23K11/24—Electric supply or control circuits therefor
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Resistance Welding (AREA)
Abstract
２枚以上の鋼板を重ね合わせた板組みに対しインバーター直流式溶接機を用いて抵抗スポット溶接を行う方法であって、予備通電段階と、パルセーション通電で行う本通電段階とを含み、本通電段階での二次側電流の電流値を１０ｋＡ以下、通電時間を６０Ｈｚ基準での０．７サイクル以下とし、休止時間を二次側電流が３ｋＡ以下まで降下するような時間とする。This is a method of performing resistance spot welding using an inverter DC welding machine to a plate assembly in which two or more steel plates are stacked, and includes a preliminary energization stage and a main energization stage performed by pulsation energization. The current value of the secondary side current in the step is set to 10 kA or less, the energization time is set to 0.7 cycle or less based on 60 Hz, and the pause time is set to the time for the secondary side current to drop to 3 kA or less.
Description
本発明は、抵抗スポット溶接方法に関するものであり、特にインバーター直流式溶接機を用いた抵抗スポット溶接方法に関する。 The present invention relates to a resistance spot welding method, and more particularly to a resistance spot welding method using an inverter DC welding machine.
自動車の車体の組み立てにおいて、プレス成形された鋼板は抵抗溶接の一種であるスポット溶接にて接合されることが多い。スポット溶接では板厚に応じて溶接部強度を確保できるようなナゲット径の確保が要求される。 In the assembly of automobile bodies, press-formed steel sheets are often joined by spot welding, which is a type of resistance welding. In spot welding, it is required to secure a nugget diameter that can secure the strength of the welded portion according to the plate thickness.
溶接中は、溶融した母材金属が鋼板から飛散するチリ（散り）が発生することがある。特に、鋼板どうしの重ね面から飛散するものは中チリ、鋼板と電極の接触面から飛散するものは表チリと呼ばれる。このようなチリが自動車の車体に付着すると車体の表面品質が低下するため、チリの発生抑制が求められる。また、スポット溶接部表面に針状の表チリが残ると自動車のワイヤハーネスを損傷する可能性がある。さらに、飛散したチリが溶接用ロボットの可動部に付着すると製造設備の正常な稼働を妨げる可能性がある。 During welding, dust (scattering) may occur in which the molten base metal scatters from the steel sheet. In particular, those scattered from the overlapping surfaces of the steel plates are called medium dust, and those scattered from the contact surface between the steel plates and the electrodes are called front dust. If such dust adheres to the vehicle body of an automobile, the surface quality of the vehicle body deteriorates, so that it is required to suppress the generation of dust. In addition, if needle-shaped surface dust remains on the surface of the spot welded portion, the wire harness of the automobile may be damaged. Furthermore, if the scattered dust adheres to the moving parts of the welding robot, it may interfere with the normal operation of the manufacturing equipment.
近年自動車の分野では、車体の軽量化と衝突安全性を実現するため、骨格部品に高強度鋼板を採用することが広まりつつある。中でも高強度鋼板を用いて熱間成形したホットスタンプ鋼板は高い成形精度と小さいプレス荷重を両立できるため、その採用が進んでいる。 In recent years, in the field of automobiles, the adoption of high-strength steel plates for skeleton parts has become widespread in order to reduce the weight of the vehicle body and realize collision safety. Among them, hot stamped steel sheets that are hot-formed using high-strength steel sheets are being adopted because they can achieve both high forming accuracy and a small press load.
しかし、通電を一度だけ行う一段通電方式で高強度鋼板をスポット溶接するとチリが発生しやすく、電流値の適正範囲を広く確保することが困難となる。また、加熱成形前の鋼板の表層に亜鉛めっきやアルミニウムめっきがあると、加熱中にめっきの酸化が進んで酸化亜鉛や酸化アルミニウムなどが形成される。これら酸化物が成長すると、鋼板の接触抵抗が上昇する。その結果、車体組み立て時のスポット溶接においてチリが発生しやすくなり、ナゲット径の安定確保が困難となるという問題もある。 However, if a high-strength steel sheet is spot-welded by a one-stage energization method in which energization is performed only once, dust is likely to occur, and it becomes difficult to secure a wide appropriate range of current values. Further, if the surface layer of the steel sheet before heat molding has zinc plating or aluminum plating, the plating is oxidized during heating to form zinc oxide, aluminum oxide, and the like. As these oxides grow, the contact resistance of the steel sheet increases. As a result, dust is likely to occur in spot welding during vehicle body assembly, and there is also a problem that it is difficult to secure a stable nugget diameter.
このような問題に対して、特開２０１０−１８８４０８には、予備通電により鋼板の接触面同士のなじみを向上させた後に本通電を行う二段通電方式を採用することにより、高強度鋼板のスポット溶接におけるチリの発生を抑制するスポット溶接方法が開示されている。また、そのような予備通電と本通電を用いる二段通電方式をホットスタンプ鋼板のスポット溶接に適用した例として、国際公開第２０１５／００５１３４号公報では酸化亜鉛等の電気抵抗の高い被膜で覆われたホットスタンプ鋼板をスポット溶接する際に予備通電を溶接電極で鋼板を加圧しながら通電と休止を複数回繰り返すパルセーション通電で行い、その後パルセーション通電時の最大通電時間よりも長い時間で連続的に本通電するようにした方法が開示されている。また、国際公開第２０１５／０９３５６８号公報では、これ同様の鋼板をスポット溶接する際に予備通電と本通電とをパルセーション通電で行い、かつ本通電の最大電流を予備通電の最大電流より高くするようにした方法が開示されている。これらの文献の方法では、予備通電時に通電と休止とを繰り返すことにより熱膨張・収縮による振動を鋼板の電極接触面に与えて、高融点の酸化物層を効果的に溶接部の外側に排除することができるとともに、パルセーション中の通電休止により電極の冷却効果を十分に働かせて、溶接部の急激な温度上昇を抑制することができる。このため、短時間で鋼板の接触面同士のなじみを向上させることができる。また、接触界面での電流密度の上昇を抑制し急激なナゲット成長を抑制することができるため、チリの発生を抑制することができる。 In response to such a problem, Japanese Patent Application Laid-Open No. 2010-188408 adopts a two-stage energization method in which the contact surfaces of the steel sheets are improved in familiarity with each other by preliminary energization and then the main energization is performed. A spot welding method for suppressing the generation of dust in welding is disclosed. Further, as an example of applying such a two-stage energization method using pre-energization and main energization to spot welding of a hot stamped steel sheet, it is covered with a film having high electrical resistance such as zinc oxide in International Publication No. 2015/005134. When spot-welding a hot stamped steel sheet, pre-energization is performed by pulsation energization, which repeats energization and pause multiple times while pressurizing the steel sheet with the welding electrode, and then continuously for a longer time than the maximum energization time during pulsation energization. Disclosed is a method of main energization. Further, in International Publication No. 2015/093568, when spot welding a similar steel sheet, pre-energization and main energization are performed by pulsation energization, and the maximum current of the main energization is made higher than the maximum current of the pre-energization. The method is disclosed. In the methods of these documents, vibration due to thermal expansion and contraction is applied to the electrode contact surface of the steel sheet by repeating energization and suspension during pre-energization, and the high melting point oxide layer is effectively removed to the outside of the weld. In addition, the cooling effect of the electrodes can be fully exerted by suspending the energization during pulsation, and the rapid temperature rise of the welded portion can be suppressed. Therefore, it is possible to improve the familiarity between the contact surfaces of the steel sheets in a short time. Further, since the increase in the current density at the contact interface can be suppressed and the rapid nugget growth can be suppressed, the generation of dust can be suppressed.
本通電を連続通電で行うと、通電初期では抵抗の高い鋼板表面の影響で鋼板間だけでなく鋼板と電極の間でも急激に発熱する。そして、通電後期には鋼板に垂直な方向へのナゲット成長が大きくなり、表チリが発生しやすくなる。そこで、国際公開第２０１５／０９３５６８号公報にあるように、本通電においても電流をパルセーションすることで、鋼板の発熱を緩やかに促進し、チリの発生を抑制することができることがわかっている。また、パルセーションを行うと、熱膨張・収縮による振動を接触面に与えるため、高融点の酸化物層を効果的に破壊することができる。これにより電極と鋼板の間や鋼板どうしの接触界面に多数の通電点を形成することができ、界面での電流密度の上昇を抑制し急激なナゲット成長を抑制することができる。この作用によっても中チリ、表チリを発生させないようにできる。 When the main energization is carried out continuously, heat is rapidly generated not only between the steel plates but also between the steel plates and the electrodes due to the influence of the surface of the steel plate having high resistance at the initial stage of energization. Then, in the latter stage of energization, the nugget growth in the direction perpendicular to the steel sheet becomes large, and surface dust is likely to occur. Therefore, as described in International Publication No. 2015/093568, it is known that the heat generation of the steel sheet can be gradually promoted and the generation of dust can be suppressed by pulsating the current even in the main energization. Further, when pulsation is performed, vibration due to thermal expansion and contraction is applied to the contact surface, so that the oxide layer having a high melting point can be effectively destroyed. As a result, a large number of current-carrying points can be formed between the electrode and the steel plate or at the contact interface between the steel plates, and an increase in the current density at the interface can be suppressed to suppress rapid nugget growth. This action can also prevent the generation of middle dust and surface dust.
しかし、上記国際公開公報のように通電を長く休止してしまうと、成長途中のナゲットが冷えすぎて一時的に小さくなってしまい、ナゲットは拡大と縮小を繰り返しながらゆっくり成長していると考えられる。つまり、必要なナゲット径を得るために本通電の継続時間が長くなってしまっている。電極が接触する鋼板表面は表チリを抑えるためある程度の冷却が必要であるが、休止時間が長いと今度はナゲットを成長させるべき鋼板どうしの界面が冷却されすぎてナゲット成長を阻害してしまうという不都合がある。 However, if the energization is suspended for a long time as in the above-mentioned international publication, it is considered that the nugget in the middle of growth becomes too cold and temporarily becomes smaller, and the nugget grows slowly while repeating expansion and contraction. .. That is, the duration of the main energization is long in order to obtain the required nugget diameter. The surface of the steel sheet that the electrodes come into contact with requires some cooling to suppress surface dust, but if the rest time is long, the interface between the steel sheets on which the nugget should grow is cooled too much, which hinders the growth of the nugget. There is an inconvenience.
一般の普通鋼板の溶接では交流式溶接機を用いると休止時間の分だけ熱効率が悪いため、インバーター直流電源を用いたインバーター直流式溶接機の方が溶接時間が短くて良いと言われる。しかし、表面に酸化物があるホットスタンプ鋼板の場合は、直流で一気に加熱するとナゲットが急成長したり、鋼板表面の酸化物の存在によりナゲットが偏って形成されたりして表チリにつながりやすい。また、インバーター直流式はトランスが小さいため溶接ロボットを小型化できるという利点がある。しかし、実際にはインバーター直流式より交流式の方がチリを抑制できることがわかっている。したがって、本発明者らは交流式での通電条件に関する知見をもとに、直流電源を用いたパルセーション通電でも似たような通電条件を採用すれば溶接時間を長くせずにチリを抑えられると考え、検討を進めた。 In general welding of ordinary steel sheets, if an AC welding machine is used, the thermal efficiency is poor due to the downtime, so it is said that an inverter DC welding machine using an inverter DC power supply may have a shorter welding time. However, in the case of a hot stamped steel sheet having an oxide on the surface, the nugget grows rapidly when heated at once with direct current, or the nugget is unevenly formed due to the presence of the oxide on the surface of the steel sheet, which tends to lead to surface dust. In addition, the inverter DC type has the advantage that the welding robot can be miniaturized because the transformer is small. However, in reality, it is known that the AC type can suppress dust more than the inverter DC type. Therefore, the present inventors can suppress dust without lengthening the welding time by adopting similar energization conditions even in pulsation energization using a DC power supply based on the knowledge about the energization conditions in the AC type. I thought, and proceeded with the examination.
本発明の一つの側面は、２枚以上の鋼板を重ね合わせた板組みに対しインバーター直流式溶接機を用いて抵抗スポット溶接を行う方法であって、予備通電段階と、パルセーション通電で行う本通電段階とを含み、本通電段階での二次側電流の電流値を１０ｋＡ以下、通電時間を６０Ｈｚ基準での０．７サイクル以下とし、休止時間を二次側電流が３ｋＡ以下まで降下するような時間とする方法である。実施形態によっては、本通電段階での通電時間を０．３サイクルとする。また実施形態によっては、本通電段階での休止時間を０．２サイクルとする。また実施形態によっては、本通電段階でのパルス数を４０回以上とする。 One aspect of the present invention is a method of performing resistance spot welding using an inverter DC welding machine on a plate assembly in which two or more steel plates are stacked, and this is performed by a preliminary energization stage and a pulsation energization. Including the energization stage, the current value of the secondary side current in the main energization stage should be 10 kA or less, the energization time should be 0.7 cycles or less based on 60 Hz, and the pause time should be reduced to 3 kA or less for the secondary side current. It is a way to make time. Depending on the embodiment, the energization time in the main energization stage is set to 0.3 cycles. Further, depending on the embodiment, the rest time in the main energization stage is set to 0.2 cycle. Further, depending on the embodiment, the number of pulses in the main energization stage is set to 40 or more.
実施形態によっては、上記の方法を用いると溶接時間を長くせずにチリを抑制することができる。 Depending on the embodiment, dust can be suppressed without lengthening the welding time by using the above method.
本発明の実施形態を以下に図面を用いて説明する。 Embodiments of the present invention will be described below with reference to the drawings.
［溶接に用いる鋼板］
本方法の溶接には、ホットスタンプ（熱間プレス）成形された鋼板（ここではホットスタンプ鋼板と呼ぶ）を使用するとよい。ホットスタンプは、鋼板素材を焼き入れ可能な温度まで加熱しオーステナイト化した後、金型でプレス成形と同時に冷却し焼き入れする工法である。したがって、ホットスタンプ鋼板は表面に酸化鉄等の酸化物層を有している。ホットスタンプ鋼板の引張強度は例えば１４７０ＭＰａ以上となる。また、溶接には、亜鉛系めっき、アルミニウム系めっきなどの表面処理が施された鋼板素材にホットスタンプ成形を施した鋼板（表面処理ホットスタンプ鋼板）を使用しても良い。このようなめっきは、高温に加熱したときに鋼板の表面に酸化物層（スケール）が発生するのを防止するために施される。このような表面処理ホットスタンプ鋼板は、亜鉛系またはアルミニウム系のめっき被膜と基材の鋼との合金化反応によって、金属間化合物や鉄基の固溶体がその表面に形成されており、さらにその外面にめっきに由来する金属（亜鉛やアルミニウムなど）を主成分とする酸化物層を有している。そのため、表面処理ホットスタンプ鋼板は裸の鋼板と比べて接触抵抗が１ｍΩ以上と高く、通電による発熱量が大きい。以上のようなホットスタンプ鋼板を２枚以上重ね合わせて、溶接対象となる板組みを構成する。板組みの中で溶接時に電極が当たる鋼板のいずれかは表面処理ホットスタンプ鋼板であると好ましい。[Steel sheet used for welding]
For welding in this method, a hot stamped (hot stamped) formed steel sheet (referred to here as a hot stamped steel sheet) may be used. Hot stamping is a method in which a steel sheet material is heated to a temperature at which it can be hardened to become austenite, and then cooled and hardened at the same time as press molding with a mold. Therefore, the hot stamped steel sheet has an oxide layer such as iron oxide on the surface. The tensile strength of the hot stamped steel sheet is, for example, 1470 MPa or more. Further, for welding, a steel plate (surface-treated hot-stamped steel plate) obtained by hot-stamping a steel plate material having been subjected to surface treatment such as zinc-based plating or aluminum-based plating may be used. Such plating is applied to prevent the formation of an oxide layer (scale) on the surface of the steel sheet when heated to a high temperature. In such a surface-treated hot stamped steel sheet, an intermetallic compound or a solid solution of an iron group is formed on the surface by an alloying reaction between a zinc-based or aluminum-based plating film and a base steel, and the outer surface thereof is further formed. It has an oxide layer whose main component is a metal (zinc, aluminum, etc.) derived from plating. Therefore, the surface-treated hot stamped steel sheet has a higher contact resistance of 1 mΩ or more than the bare steel sheet, and the amount of heat generated by energization is large. Two or more hot stamped steel sheets as described above are superposed to form a plate assembly to be welded. It is preferable that any of the steel plates to which the electrodes hit during welding in the plate assembly is a surface-treated hot stamped steel plate.
［溶接方法］
溶接は抵抗溶接法の一種であるスポット溶接で行う。溶接は予備通電と本通電とを組み合わせる二段通電方式で行う。図５に予備通電と本通電の例を示す。本通電は溶接部となるナゲットを成長させるためのものである。これに対し、予備通電は、鋼板表面の電極と接触する領域や鋼板どうしの界面のなじみを向上させることを主たる目的として行われるものである。溶接機はインバーター直流式のものを用いる。インバーター直流式は単相交流式など他の方式と比べてトランス（変圧器）を小さくできるため、可搬重量の小さいロボットに搭載できるという利点がある。インバーター式溶接機の電源装置は通常、インバーター回路（スイッチング素子から構成される）とトランスと整流回路を含み、インバーター回路で作り出した交流パルス電流（一次側電流）をトランスで所望の電流値を有する電流（二次側電流）に変換し、この二次側電流を溶接電流として電極間に流して溶接を行う。図５のグラフは設定された二次側電流の波形を示している。予備通電と本通電の設定波形、すなわち継続時間ｔａ、ｔｂ（あるいはパルス数）や電流Ｉａ、Ｉｂ（パルスの高さ）の設定値は、タイマーとも呼ばれる制御装置を通して入力される。インバーター直流式溶接機はさらにトランスの二次側に整流回路を備え、この整流回路で直流化された二次側電流を溶接電流として用いる。インバーター直流式溶接機は、例えば、特開２０００−１５８１４８号に開示されているものを用いることができる。電極は任意のものを用いることができる。例えばＤＲ（ドームラジアス）型電極を使用できる。ＤＲ型電極は、例えば先端径６ｍｍ、先端曲率半径４０ｍｍのものを用いることができる。しかし、曲率半径を３０ｍｍ以下とすることで電極先端部が鋼板に作用する面圧を増大させ、鋼板表面の酸化物を分散させる効果を増大させても良い。溶接を行う間、電極で鋼板の板組みを所定の加圧力で挟持する。この電極による加圧力は通常用いられる範囲に設定することができる。しかし、加圧力を大きくすることにより鋼板表面の酸化物層を破壊・分散させ、その一部を電極の接触範囲外の方向に移動（排除）させるようにして、表面の接触抵抗を低下させることができる。例えば、加圧力を４００ｋｇｆ（＝３．９ｋＮ）以上とすることができる。[Welding method]
Welding is performed by spot welding, which is a type of resistance welding method. Welding is performed by a two-stage energization method that combines pre-energization and main energization. FIG. 5 shows an example of preliminary energization and main energization. This energization is for growing the nugget that will be the weld. On the other hand, the pre-energization is performed mainly for the purpose of improving the area in contact with the electrodes on the surface of the steel sheet and the compatibility of the interface between the steel sheets. Use an inverter DC type welding machine. The inverter DC type has the advantage that it can be mounted on a robot with a small payload because the transformer can be made smaller than other methods such as the single-phase AC type. The power supply device of an inverter type welding machine usually includes an inverter circuit (composed of a switching element), a transformer, and a rectifying circuit, and the AC pulse current (primary side current) generated by the inverter circuit has a desired current value in the transformer. It is converted into an electric current (secondary side current), and this secondary side current is passed between the electrodes as a welding current to perform welding. The graph of FIG. 5 shows the waveform of the set secondary current. Preliminary energization and the energization setting waveform, i.e. the set value of the duration t a, t b (or number of pulses) and the current I a, I b (pulse height) is input through the control unit, also referred to as a timer. The inverter DC welding machine is further equipped with a rectifier circuit on the secondary side of the transformer, and the secondary side current converted to DC by this rectifier circuit is used as the welding current. As the inverter DC welding machine, for example, the one disclosed in JP-A-2000-158148 can be used. Any electrode can be used. For example, a DR (Dome Radius) type electrode can be used. As the DR type electrode, for example, one having a tip diameter of 6 mm and a tip curvature radius of 40 mm can be used. However, by setting the radius of curvature to 30 mm or less, the surface pressure of the tip of the electrode acting on the steel sheet may be increased to increase the effect of dispersing the oxide on the surface of the steel sheet. During the welding, the plate assembly of the steel plate is sandwiched by the electrodes with a predetermined pressing force. The pressing force by this electrode can be set within the range normally used. However, by increasing the pressing force, the oxide layer on the surface of the steel sheet is destroyed and dispersed, and a part of the oxide layer is moved (excluded) in a direction outside the contact range of the electrodes to reduce the contact resistance of the surface. Can be done. For example, the pressing force can be 400 kgf (= 3.9 kN) or more.
［予備通電］
予備通電は連続通電で行っても、パルセーション通電で行ってもよい。図５は予備通電を連続通電で行った例を示している。予備通電を連続通電で行う場合、電流値Ｉａは６ｋＡ以下とすることが好ましい。これにより、チリの発生を抑えながら鋼板表面の接触抵抗を低下させることができる。また、予備通電の電流値は本通電の電流値よりも高くするのが好ましい。さらに、予備通電の通電時間ｔａは、電流値と通電時間との積Ｉａｔａが２ｋＡ・ｍｓ以下となる範囲で長めに設定することが好ましい。これにより、酸化物の分散（排除）効果が増大し、電流値の適正範囲を拡大することができる。[Preliminary energization]
The preliminary energization may be performed by continuous energization or pulsation energization. FIG. 5 shows an example in which preliminary energization is performed by continuous energization. When the pre-energization is performed continuously, the current value I a is preferably 6 kA or less. As a result, the contact resistance on the surface of the steel sheet can be reduced while suppressing the generation of dust. Further, it is preferable that the current value of the preliminary energization is higher than the current value of the main energization. Further, the energization time t a of the preliminary energization, it is preferable that the product I a t a between the energizing time and the current value set longer within a range equal to or less than 2 kA · ms. As a result, the effect of dispersing (excluding) the oxide is increased, and the appropriate range of the current value can be expanded.
［本通電］
予備通電が終わると本通電を開始する。図５に示すように、本通電はパルス波形をもつ直流電流を用いるパルセーション通電で行う。予備通電との境目では、電流をオフにすることなく最初のパルスにつなげても、あるいは最小限の休止時間をおいてから最初のパルスに入っても良い。[Main energization]
When the preliminary energization is completed, the main energization is started. As shown in FIG. 5, the main energization is performed by pulsation energization using a direct current having a pulse waveform. At the boundary with the pre-energization, the current may be connected to the first pulse without being turned off, or the first pulse may be entered after a minimum pause time.
［電流値］
本通電では二次側電流の設定値Ｉｂを１０ｋＡ以下とする。なお、必要に応じて電流値は１０ｋＡ以下の範囲内で徐々に、あるいはパルスごとに、変化させても良い。例えば、徐々に電流値を上昇させることにより、通電初期の接触抵抗が高い時期のナゲットの生成及び急成長を抑制することもできる。一般に、スポット溶接での電流は定電流制御される。[Current value]
In this energized or less 10kA settings I b of the secondary side current. If necessary, the current value may be changed gradually or pulse by pulse within the range of 10 kA or less. For example, by gradually increasing the current value, it is possible to suppress the formation and rapid growth of nuggets during the period when the contact resistance at the initial stage of energization is high. Generally, the current in spot welding is controlled by a constant current.
［通電・休止時間］
本通電では通電時間（二次側電流の設定波形のパルス幅）を０．７サイクル（１１．７ｍｓ）以下とする。なお、本願で言うサイクルは周波数６０Ｈｚに基づく単位であり、１サイクルは約１６．７ｍｓである。休止時間（二次側電流の設定波形のパルス間隔）は、インバーター直流式溶接機の電源装置の二次側電流の応答特性に基づいて決定する。二次側電流は一般に一次側電流の矩形パルスの変化に遅れて応答するため、例えば図５のように設定波形の電流値が急激に０に落ちても実際に電極間を流れる二次側電流の実効値は比較的なだらかに降下する。休止時間は、具体的には、二次側電流の実効値が３ｋＡ以下まで降下するような時間とするのが良い。このような条件を満たす休止時間は当業者であれば適当な実験で求めることができる。一例として、通電時間を０．３サイクル（５ｍｓ）、休止時間を０．２サイクル（３．３ｍｓ）とすることができる。[Energization / pause time]
In the main energization, the energization time (pulse width of the set waveform of the secondary side current) is set to 0.7 cycle (11.7 ms) or less. The cycle referred to in the present application is a unit based on a frequency of 60 Hz, and one cycle is about 16.7 ms. The pause time (pulse interval of the set waveform of the secondary side current) is determined based on the response characteristics of the secondary side current of the power supply device of the inverter DC welding machine. Since the secondary side current generally responds after a change in the rectangular pulse of the primary side current, the secondary side current that actually flows between the electrodes even if the current value of the set waveform suddenly drops to 0 as shown in FIG. 5, for example. The effective value of is relatively gentle. Specifically, the rest time should be a time such that the effective value of the secondary side current drops to 3 kA or less. A person skilled in the art can obtain a rest time satisfying such a condition by an appropriate experiment. As an example, the energization time can be 0.3 cycle (5 ms) and the rest time can be 0.2 cycle (3.3 ms).
休止時間の上限は必要なナゲット径が得られるように設定すればよい。休止時間が長いと二次側電流値は０にまで降下するが、ナゲットが成長するのであればそれでも問題はない。しかし、休止時間を長くすると全体の溶接時間が長くなるため、製造効率を上げるには例えば休止時間をぎりぎり３ｋＡ以下まで下がるような時間とすればよい。 The upper limit of the rest time may be set so that the required nugget diameter can be obtained. If the rest time is long, the secondary current value drops to 0, but if the nugget grows, there is no problem. However, if the pause time is lengthened, the entire welding time becomes long. Therefore, in order to improve the manufacturing efficiency, for example, the pause time may be set to a time that is as low as 3 kA or less.
［パルス数］
本通電でのパルス数は、上記の他の条件に応じて、所望のナゲット径が達成できるように設定する。例えば、パルス数は４０回以上とすることができる。パルス数は板厚ｔに対してどれほどのナゲット径を目標値とするか（例えば５√ｔ）によって変える。パルス波形（すなわち通電時間と休止時間）が一定であれば、本通電の継続時間ｔｂはパルス数によって決まる。パルス数は当業者であれば実験的にあるいは総通電時間などから経験的に決定することができる。[Number of pulses]
The number of pulses in the main energization is set so that a desired nugget diameter can be achieved according to the other conditions described above. For example, the number of pulses can be 40 or more. The number of pulses is changed depending on how much nugget diameter is set as the target value with respect to the plate thickness t (for example, 5√t). If the pulse waveform (that is, the energization time and the rest time) is constant, the duration t b of the main energization is determined by the number of pulses. Those skilled in the art can determine the number of pulses experimentally or empirically from the total energization time.
以上、具体的な実施形態を用いて本発明を説明したが、本発明はこれらの実施形態に限定されることなく、当業者であれば本発明の目的を逸脱することなく様々な置換、改良、変更を施すことが可能である。 Although the present invention has been described above using specific embodiments, the present invention is not limited to these embodiments, and those skilled in the art can make various substitutions and improvements without deviating from the object of the present invention. , It is possible to make changes.
［実験例］
板厚１．４ｍｍ、幅３０ｍｍ、長さ１００ｍｍの１４７０ＭＰａの合金化溶融亜鉛めっき鋼板（ＧＡ）素材にホットスタンプを施すことにより、ホットスタンプ鋼板のサンプルを２枚作成した。この２枚のサンプルを重ね合わせた板組みに対して二段通電方式で抵抗スポット溶接を実施した。スポット溶接機は、先端曲面部の直径が６ｍｍ、曲率半径が４０ｍｍのＤＲ型電極（クロム銅製）を備えたインバーター直流式のものを用いた。予備通電は連続通電で行い、電流設定値は４ｋＡ、通電時間は６サイクル（１００ｍｓ）、加圧力は４．５ｋＮとした。本通電はパルセーション通電で行った。本通電の電流設定値は様々に変え、またパルセーションの通電時間と休止時間は０．１サイクル単位で様々に変えた。パルス数は板厚をｔ（＝１．４ｍｍ）としてナゲット径が５√ｔ（＝５．９ｍｍ）となるように設定した。本通電での加圧力は４．５ｋＮとした。各条件のもとで溶接実験を複数回行い、表チリの発生率を計算した。また、休止時間に降下する電流の下限値をグラフから読み取った。実験結果を表１に示す。代表として、条件３、４については二次側電流の電流波形（実効値）を図１、３に示す。図２、４はそれぞれ図１、３の電流波形の部分拡大図である。[Experimental example]
Two samples of hot stamped steel sheets were prepared by hot stamping an alloyed hot-dip galvanized steel sheet (GA) material having a plate thickness of 1.4 mm, a width of 30 mm, and a length of 100 mm at 1470 MPa. Resistance spot welding was performed on the plate assembly in which these two samples were superposed by a two-stage energization method. As the spot welder, an inverter DC type equipped with a DR type electrode (made of chrome copper) having a curved tip having a diameter of 6 mm and a radius of curvature of 40 mm was used. The pre-energization was continuous energization, the current set value was 4 kA, the energization time was 6 cycles (100 ms), and the pressing force was 4.5 kN. This energization was performed by pulsation energization. The current setting value of the main energization was changed variously, and the energization time and the rest time of the pulsation were changed in 0.1 cycle units. The number of pulses was set so that the plate thickness was t (= 1.4 mm) and the nugget diameter was 5√t (= 5.9 mm). The pressing force in the main energization was 4.5 kN. Welding experiments were performed multiple times under each condition, and the incidence of table dust was calculated. In addition, the lower limit of the current that falls during the pause time was read from the graph. The experimental results are shown in Table 1. As a representative, for
表１からは、通電時間が０．７サイクル以下であれば、休止時間に降下した電流の下限値が３ｋＡを下回ったとき（条件３、５、６、７、９）にチリが発生しないことが読み取れる。図２、４では分かり易いように下限値３．０ｋＡを破線で表示している。特に、通電時間０．３サイクル（５ｍｓ）のときに休止時間０．２サイクル（３．３ｍｓ）とした場合（条件３）では、本通電の継続時間を非常に短くできることが分かった。これは、通電時間が短いため接触抵抗の高い鋼板間に比べて鋼板と電極の間での発熱が小さく、その分短時間で鋼板表面を冷却でき、表チリが少なくなるためであると考えられる。さらに休止時間も短いため、鋼板間のナゲット成長への影響は少ないと考えられるうえ、全体の溶接時間も短くできる。
From Table 1, if the energization time is 0.7 cycles or less, dust does not occur when the lower limit of the current dropped during the pause time falls below 3 kA (
これに対し、従来のように通電時間を１サイクル以上に長くした条件１、２では、二次側電流（実効値）の下限値が０にまで落ちるような休止時間を選んでもチリが発生した。通電中は接触抵抗の高い鋼板間だけでなく鋼板と電極の間でも発熱が大きく、表チリの発生につながったと考えられる。チリ発生を防ぐにはさらに休止時間を長くする必要があるが、そうすると鋼板と電極の間だけでなく鋼板間も冷却されるため、パルス数を増やし本通電の継続時間を確保する必要があり、全体の溶接時間が延びてしまう。また、通電時間を０．３サイクル（５ｍｓ）と短くしても、休止時間が長いために降下する電流の下限値が４．５〜６．０ｋＡに留まった条件４では、表チリが高頻度で発生した。
Claims (4)
予備通電段階と、パルセーション通電で行う本通電段階とを含み、本通電段階での二次側電流の電流値を１０ｋＡ以下、通電時間を６０Ｈｚ基準での０．７サイクル以下とし、休止時間を二次側電流が３ｋＡ以下まで降下するような時間とする方法。It is a method of performing resistance spot welding using an inverter DC welding machine for a plate assembly in which two or more steel plates are stacked.
Including the pre-energization stage and the main energization stage performed by pulsation energization, the current value of the secondary side current in the main energization stage is 10 kA or less, the energization time is 0.7 cycle or less based on 60 Hz, and the pause time is set. A method in which the time is set so that the secondary current drops to 3 kA or less.
The method according to claim 3, wherein the number of pulses in the main energization stage is 40 or more.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2018162701 | 2018-08-31 | ||
| JP2018162701 | 2018-08-31 | ||
| PCT/JP2019/034368 WO2020045678A1 (en) | 2018-08-31 | 2019-09-02 | Resistance spot welding method |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPWO2020045678A1 true JPWO2020045678A1 (en) | 2021-02-18 |
Family
ID=69643915
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2020539656A Pending JPWO2020045678A1 (en) | 2018-08-31 | 2019-09-02 | Resistance spot welding method |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JPWO2020045678A1 (en) |
| WO (1) | WO2020045678A1 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114850643A (en) * | 2021-02-04 | 2022-08-05 | 杭州宝伟汽车零部件有限公司 | Spot welding method for ultrahigh-strength hot-formed steel plate |
| WO2022219968A1 (en) * | 2021-04-12 | 2022-10-20 | Ｊｆｅスチール株式会社 | Resistance spot welding method |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2008093726A (en) * | 2006-10-16 | 2008-04-24 | Nippon Steel Corp | Lap resistance spot welding method |
| JP2010207909A (en) * | 2009-02-12 | 2010-09-24 | Sumitomo Metal Ind Ltd | Resistance welding method for high tensile strength steel sheet and method for producing resistance welded joint |
| JP2010247215A (en) * | 2009-04-20 | 2010-11-04 | Sumitomo Metal Ind Ltd | Resistance welding method of high tensile steel sheet |
| WO2015093568A1 (en) * | 2013-12-20 | 2015-06-25 | 新日鐵住金株式会社 | Resistance spot welding method |
-
2019
- 2019-09-02 JP JP2020539656A patent/JPWO2020045678A1/en active Pending
- 2019-09-02 WO PCT/JP2019/034368 patent/WO2020045678A1/en active Application Filing
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2008093726A (en) * | 2006-10-16 | 2008-04-24 | Nippon Steel Corp | Lap resistance spot welding method |
| JP2010207909A (en) * | 2009-02-12 | 2010-09-24 | Sumitomo Metal Ind Ltd | Resistance welding method for high tensile strength steel sheet and method for producing resistance welded joint |
| JP2010247215A (en) * | 2009-04-20 | 2010-11-04 | Sumitomo Metal Ind Ltd | Resistance welding method of high tensile steel sheet |
| WO2015093568A1 (en) * | 2013-12-20 | 2015-06-25 | 新日鐵住金株式会社 | Resistance spot welding method |
Also Published As
| Publication number | Publication date |
|---|---|
| WO2020045678A1 (en) | 2020-03-05 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP6584728B1 (en) | Method of manufacturing resistance spot welded joint | |
| JP6094676B2 (en) | Resistance spot welding method | |
| JP6593572B1 (en) | Resistance spot welded joint manufacturing method | |
| KR102225221B1 (en) | Method of manufacturing resistance spot welded joints | |
| US10259071B2 (en) | Resistive welding electrode and method for spot welding steel and aluminum alloy workpieces with the resistive welding electrode | |
| KR101979558B1 (en) | Resistance spot welding method | |
| JP2008093726A (en) | Lap resistance spot welding method | |
| CN110202245B (en) | Mechanical property improvement of aluminum-steel welding seam by limiting deformation of steel plate | |
| JPWO2020045678A1 (en) | Resistance spot welding method | |
| CN110475642B (en) | Method for manufacturing resistance spot-welded joint | |
| JPWO2015133099A1 (en) | Resistance spot welding method | |
| JPWO2017033455A1 (en) | Resistance spot welding method and manufacturing method of welded member | |
| JP6584729B1 (en) | Method of manufacturing resistance spot welded joint | |
| CN110270750B (en) | Resistance spot welding workpiece stack comprising a steel workpiece and an aluminum workpiece having a steel plate | |
| JP2019155473A (en) | Method for manufacturing resistance spot welding member | |
| KR101957628B1 (en) | Mechanical bonding apparatus and mechanical bonding method | |
| Tanmoy | Resistance Spot Welding: Principles and Its Applications | |
| JPH01210180A (en) | Electrode for spot welding | |
| WO2023008263A1 (en) | Resistance spot welding method | |
| US20230311233A1 (en) | Spot welding method | |
| KR20240019358A (en) | welding method | |
| JP2022063070A (en) | Spot welding method | |
| KR20230148379A (en) | Resistance spot welding method | |
| JP2023066438A (en) | Metal joined body and method for manufacturing the same |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A621 | Written request for application examination |
Free format text: JAPANESE INTERMEDIATE CODE: A621 Effective date: 20200908 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20210810 |
|
| A521 | Request for written amendment filed |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20211008 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20220315 |
|
| A521 | Request for written amendment filed |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20220516 |
|
| A02 | Decision of refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A02 Effective date: 20221004 |
|
| C60 | Trial request (containing other claim documents, opposition documents) |
Free format text: JAPANESE INTERMEDIATE CODE: C60 Effective date: 20221228 |