JP2014113618A - Resistance welding inspection method and resistance welding device - Google Patents

Resistance welding inspection method and resistance welding device Download PDF

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JP2014113618A
JP2014113618A JP2012269417A JP2012269417A JP2014113618A JP 2014113618 A JP2014113618 A JP 2014113618A JP 2012269417 A JP2012269417 A JP 2012269417A JP 2012269417 A JP2012269417 A JP 2012269417A JP 2014113618 A JP2014113618 A JP 2014113618A
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temperature
steel plate
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resistance welding
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JP5871787B2 (en
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Sumitomo Watanabe
純友 渡邉
Eisaku Hasegawa
栄作 長谷川
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Honda Motor Co Ltd
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Abstract

PROBLEM TO BE SOLVED: To provide a technique that can predict a volume of a welding part.SOLUTION: Fig. (b) corresponds to a curve b, and a large welding parts 36, 36 are recognized. Fig. (c) corresponds to a curve c, and the welding parts 36, 36 smaller than that in Fig. (b) are recognized. Fig. (d) corresponds to a curve d, and the welding parts 36, 36 are extremely small. From the above knowledge, temperature curves b, c, d of Fig. (a) are acquired, and the presence or absence of a rise in temperature generated immediately after separation of a main electrode from one steel plate is inspected. It can be determined that the welding parts 36, 36 have not reached the necessary size because the rise in temperature is not recognized in the curve d. Also, it can be determined that the welding parts 36, 36 have sizes larger than necessary because a sufficiently large rise in temperature δb is recognized in the curve b. Also, it can be determined that the welding parts 36, 36 have the necessary sizes because a sufficiently large rise in temperature δc is recognized in the curve c. Therefore, the volume of the welding parts can be predicted without performing destructive inspection.

Description

本発明は、少なくとも2枚の鋼板を接合するスポット溶接技術に関する。   The present invention relates to a spot welding technique for joining at least two steel plates.

薄い鋼板同士を接合する車体製造ラインでは、スポット(点)溶接が採用される。スポット溶接ではナゲットと呼ばれる溶着部の大きさが接合強度に影響するため、溶着部の大きさを確かめることが求められる。
サンプルを切断し、切断面に現れる溶着部を観察する破壊検査方法の他、ワークを傷めない非破壊検査方法も各種提案されてきた(例えば、特許文献1(図1)参照。)。
Spot (point) welding is employed in a vehicle body production line for joining thin steel plates. In spot welding, since the size of the welded portion called a nugget affects the joint strength, it is required to confirm the size of the welded portion.
In addition to a destructive inspection method for cutting a sample and observing a welded portion appearing on a cut surface, various nondestructive inspection methods that do not damage a work have been proposed (see, for example, Patent Document 1 (FIG. 1)).

特許文献1の図1(c)に示されるように、一対の電極(1a、1b)(括弧付き数字は、特許文献1に記載された符号を示す。以下同様)で被溶接材(S1、S2)間にナゲット(N)を生成した後、溶接跡を赤外線カメラ(2)で撮影することで、ナゲット(N)の大きさを求めるというものである。   As shown in FIG. 1 (c) of Patent Document 1, a pair of electrodes (1a, 1b) (the numbers in parentheses indicate the symbols described in Patent Document 1. The same applies hereinafter), the work piece (S1, After the nugget (N) is generated during S2), the size of the nugget (N) is obtained by photographing the welding trace with the infrared camera (2).

非破壊検査であるため全数検査が可能となる。
赤外線カメラ(2)で撮影するため、ナゲット(N)の面積(平面積)が求まるだけである。
一方、破壊検査では、切断面を観察する。この観察で、被溶接材(S1)と被溶接材(S2)に跨る(板厚さ方向の)ナゲット(N)の面積(縦面積)を求める。平面面積と共に縦面積も接合強度に大きく影響する。
100% inspection is possible because of non-destructive inspection.
Since the image is taken by the infrared camera (2), only the area (plane area) of the nugget (N) is obtained.
On the other hand, in the destructive inspection, the cut surface is observed. With this observation, the area (vertical area) of the nugget (N) (in the thickness direction) straddling the workpiece (S1) and the workpiece (S2) is obtained. The vertical area as well as the planar area greatly affects the bonding strength.

すなわち、ナゲット(N)による接合強度は、ナゲット(N)の体積に強く相関があり、特許文献1のように平面積を求めるだけでは検査結果の信頼性が低下する。
そこで、ナゲット(溶着部)の体積を、予測し評価することができる技術が求められる。
That is, the bonding strength by the nugget (N) has a strong correlation with the volume of the nugget (N), and the reliability of the inspection result is lowered only by obtaining the flat area as in Patent Document 1.
Therefore, a technique capable of predicting and evaluating the volume of the nugget (welded portion) is required.

特開平7−63694号公報Japanese Patent Laid-Open No. 7-63694

本発明は、溶着部の体積を予測することができる技術を提供することを課題とする。   This invention makes it a subject to provide the technique which can estimate the volume of a welding part.

請求項1に係る発明は、少なくとも2枚の鋼板を積層し、一方の鋼板に主電極及びアース電極を当て、前記主電極から前記鋼板を介して前記アース電極へ通電することで、前記主電極の近傍に溶着部を生成させ、前記主電極及びアース電極を前記一方の鋼板から離す抵抗溶接作業において、前記溶着部の生成状態を検査する抵抗溶接検査方法であって、
前記主電極が前記一方の鋼板から離れる前から離れた後まで、前記主電極が当たっている若しくは当たっていた部位での前記一方の鋼板の温度を連続して測定する温度測定工程と、
この温度測定工程で得た温度曲線において、前記主電極が前記一方の鋼板から離れた後に、温度が上昇するか否か及び温度上昇の大きさに基づいて前記溶着部の生成状態を判定する判定工程とからなる。
The invention according to claim 1 is characterized in that at least two steel plates are laminated, a main electrode and a ground electrode are applied to one steel plate, and the main electrode is energized from the main electrode to the ground electrode through the steel plate. A resistance welding inspection method for inspecting the generation state of the weld portion in a resistance welding operation in which a weld portion is generated in the vicinity of the main electrode and the ground electrode from the one steel plate,
Until the main electrode is separated from the one steel plate until after it is separated, the temperature measurement step of continuously measuring the temperature of the one steel plate at the site where the main electrode is hit or hit,
In the temperature curve obtained in this temperature measurement process, after the main electrode has moved away from the one steel plate, a determination is made to determine whether or not the temperature rises and the generation state of the welded portion based on the magnitude of the temperature rise Process.

請求項2に係る発明は、積層した少なくとも2枚の鋼板からなるワークに対して相対移動自在に保持される装置フレームと、この装置フレームに主移動手段を介して移動自在に保持される主電極と、前記装置フレームにサブ移動手段を介して移動自在に保持されるアース電極と、前記主電極及び前記アース電極に結線される溶接電源とからなり、一方の鋼板に前記主電極及び前記アース電極を当て、前記主電極から前記鋼板を介して前記アース電極へ通電することで、前記主電極の近傍に溶着部を生成させる抵抗溶接装置において、
この抵抗溶接装置は、前記溶着部近傍にて前記一方の鋼板の表面温度を計測する温度計測手段と、この温度計測手段から温度情報を入力すると共に前記ワークに対応するしきい値を予め取得しておき、前記主電極を前記一方の鋼板から離した直後に温度が前記しきい値以上に上昇するか否かを判定する判定部とを備えていることを特徴とする。
According to a second aspect of the present invention, there is provided a device frame that is held in a relatively movable manner with respect to a workpiece made of at least two laminated steel plates, and a main electrode that is held in the device frame through a main moving means. And a ground electrode that is movably held on the apparatus frame via a sub-moving means, and a welding power source that is connected to the main electrode and the ground electrode, and the main electrode and the ground electrode on one steel plate In the resistance welding apparatus for generating a weld portion in the vicinity of the main electrode by energizing the ground electrode through the steel plate from the main electrode,
The resistance welding apparatus includes a temperature measuring unit that measures the surface temperature of the one steel plate in the vicinity of the welded portion, and inputs temperature information from the temperature measuring unit and acquires a threshold value corresponding to the workpiece in advance. A determination unit that determines whether or not the temperature rises above the threshold immediately after the main electrode is separated from the one steel plate is provided.

請求項3に係る発明では、温度計測手段は、一方の鋼板から放射される放射エネルギーの強さを測定し温度に変換する非接触式の放射温度計であることを特徴とする。   The invention according to claim 3 is characterized in that the temperature measuring means is a non-contact type radiation thermometer that measures the intensity of radiant energy radiated from one of the steel plates and converts it into temperature.

請求項1に係る方法では、溶融金属が凝固熱を放出した後に溶着部になることに着目したものであって、溶接不良の1つとして溶融金属ができない、若しくは僅かである場合は、主電極が鋼板から離れた後における温度上昇はゼロ又は僅かとなる。一方、溶着部の生成量が大きいほど、多くの凝固熱が放出されるため、主電極が鋼板から離れた後における温度上昇は大きくなる。
すなわち、本発明によれば、溶着部の体積を予測することができる。
The method according to claim 1 focuses on the fact that the molten metal becomes a welded portion after releasing the heat of solidification, and if the molten metal cannot be formed or is slight as one of the welding defects, The temperature rise after the separation from the steel plate is zero or slight. On the other hand, the greater the amount of welded portion generated, the more heat of solidification is released, and the temperature rise after the main electrode is separated from the steel plate increases.
That is, according to the present invention, the volume of the welded portion can be predicted.

請求項2に係る装置では、請求項1と同様に、溶着部の体積を予測することができる。加えて、通常のスポット溶接装置に、温度計測手段と判定部とを付加するだけであるから、本発明の係る抵抗溶接装置は、安価である。   In the apparatus according to the second aspect, similarly to the first aspect, the volume of the welded portion can be predicted. In addition, the resistance welding apparatus according to the present invention is inexpensive because only a temperature measuring means and a determination unit are added to a normal spot welding apparatus.

請求項3に係る発明では、温度計測手段は、非接触式の放射温度計であるため、接触式温度計測手段のように測定対象物に当てる必要がなく、測定が簡単になると共に測定の迅速を図ることができる。   In the invention according to claim 3, since the temperature measuring means is a non-contact type radiation thermometer, it is not necessary to apply it to the measurement object as in the case of the contact temperature measuring means. Can be achieved.

本発明に係る抵抗溶接装置を保持する装置移動手段の斜視図である。It is a perspective view of the apparatus movement means holding the resistance welding apparatus which concerns on this invention. 本発明に係る抵抗溶接装置の原理図である。It is a principle figure of the resistance welding apparatus which concerns on this invention. 図2の3−3線断面図である。FIG. 3 is a sectional view taken along line 3-3 in FIG. 2. 抵抗溶接装置の作用図である。It is an effect | action figure of a resistance welding apparatus. 抵抗溶接に係る主電極及び電流を示す図である。It is a figure which shows the main electrode and electric current which concern on resistance welding. 溶着部の生成過程を説明する図である。It is a figure explaining the production | generation process of a welding part. 一方の鋼板の温度を示す図である。It is a figure which shows the temperature of one steel plate. 電流と溶着部の大きさの相関を調べた図である。It is the figure which investigated the correlation of the magnitude | size of an electric current and a welding part. 溶着部の判定フロー図である。It is a determination flowchart of a welding part.

本発明の実施の形態を添付図に基づいて以下に説明する。   Embodiments of the present invention will be described below with reference to the accompanying drawings.

図1に示すように、抵抗溶接装置10は、ロボットに代表される装置移動手段11により保持され、適宜移動される。抵抗溶接装置10の詳細を次図で説明する。   As shown in FIG. 1, the resistance welding apparatus 10 is held by apparatus moving means 11 represented by a robot and is appropriately moved. Details of the resistance welding apparatus 10 will be described with reference to the next figure.

図2に示すように、抵抗溶接装置10は、ワーク12の上方に保持される装置フレーム15と、この装置フレーム15の中央に設けられる主移動手段16と、この主移動手段16から下へ延びるロッド17に取付けられる主電極18と、この主電極18を挟むようにして両側方に配置されるアース電極19、19と、装置フレーム15に設けられアース電極19、19を移動させるサブ移動手段21、21と、主電極18及びアース電極19、19に結線される溶接電源22とからなる。   As shown in FIG. 2, the resistance welding apparatus 10 includes an apparatus frame 15 held above the work 12, a main moving means 16 provided at the center of the apparatus frame 15, and extends downward from the main moving means 16. A main electrode 18 attached to the rod 17; earth electrodes 19 and 19 disposed on both sides of the main electrode 18; and sub-moving means 21 and 21 provided on the apparatus frame 15 for moving the earth electrodes 19 and 19. And a welding power source 22 connected to the main electrode 18 and the ground electrodes 19, 19.

主移動手段16はサーボモータを駆動源とするシリンダユニットが好適である。サブ移動手段21も同様である。
また、溶接電源22は装置フレーム15に載せることが望ましいが、設置位置は任意である。
The main moving means 16 is preferably a cylinder unit using a servo motor as a drive source. The sub moving means 21 is the same.
The welding power source 22 is preferably mounted on the apparatus frame 15, but the installation position is arbitrary.

最も一般的なスポット溶接装置では、一対の電極が、一直線上に上下に配置される。
本例の抵抗溶接装置10では、主電極18、アース電極19、19共にワーク12の一方の側に配置されるため、片側スポット溶接装置とも呼ばれ、特殊なスポット溶接装置の範疇に入る。すなわち、ワーク12の裏側(実施例では下側)にアースを配置する必要がなく、溶接施工の自由度が高まる。
In the most common spot welding apparatus, a pair of electrodes are arranged vertically on a straight line.
In the resistance welding apparatus 10 of this example, since the main electrode 18 and the ground electrodes 19 and 19 are both disposed on one side of the workpiece 12, it is also called a one-side spot welding apparatus and falls into the category of a special spot welding apparatus. In other words, it is not necessary to place a ground on the back side (lower side in the embodiment) of the work 12, and the degree of freedom in welding is increased.

図3に示すように、主電極18の中心線23とワーク12の上面とが交差する点24に、視野中心がくるようにして、温度計測手段としての放射温度計25が配置される。この放射温度計25を支えるスタンド26の設置位置は任意である。
放射温度計25から温度情報が送られ、この温度情報はディスプレイ27で表示されると共に判定部28に送られる。判定部28は後述する判定を実施する。
As shown in FIG. 3, a radiation thermometer 25 is disposed as a temperature measuring means so that the center of the visual field comes to a point 24 where the center line 23 of the main electrode 18 and the upper surface of the work 12 intersect. The installation position of the stand 26 that supports the radiation thermometer 25 is arbitrary.
Temperature information is sent from the radiation thermometer 25, and this temperature information is displayed on the display 27 and sent to the determination unit 28. The determination unit 28 performs determination described later.

温度計測手段25は、放射温度計の他、抵抗体を一方の鋼板に接触させて抵抗の変化で温度を測定する接触式温度計、光の波長を温度に変換する光温度計、赤外線の熱線を温度に変換する赤外線温度計など種々の手段を採用することができる。   In addition to the radiation thermometer, the temperature measuring means 25 is a contact-type thermometer that measures the temperature by changing the resistance by bringing a resistor into contact with one steel plate, an optical thermometer that converts the wavelength of light into temperature, and infrared heat rays. Various means such as an infrared thermometer for converting the temperature into temperature can be adopted.

以上に説明した抵抗溶接装置10の作用を次に述べる。
図4(a)に示すように、ワーク12は、他方の鋼板31に一方の鋼板32を積層してなり、一方の鋼板32へ主電極18を押圧すると共にアース電極19、19を当てる。アース電極19、19の押力は主電極18の押力より小さく設定する。
The operation of the resistance welding apparatus 10 described above will be described next.
As shown in FIG. 4A, the workpiece 12 is formed by laminating one steel plate 32 on the other steel plate 31, pressing the main electrode 18 against the one steel plate 32 and applying the ground electrodes 19, 19. The pressing force of the ground electrodes 19 and 19 is set smaller than the pressing force of the main electrode 18.

図4(b)は、(a)のb部拡大図であり、他方の鋼板31及び一方の鋼板32は下へ凸になるように変形する。一方の鋼板32の変曲点33、33より、中心寄り範囲Aでは、他方の鋼板31は一方の鋼板32に密着し、電気抵抗は小さくなる。変曲点33、33より、外側の範囲C、Cでは、他方の鋼板31と一方の鋼板32との間に隙間ができるなどして、通電性が期待できない。
変曲点33、33付近の範囲B、Bは、範囲Aと範囲Cの中間の性質を有し、通電性は確保されるものの電気抵抗は範囲Aより格段に大きくなる。
FIG. 4B is an enlarged view of part b of FIG. 4A, and the other steel plate 31 and one steel plate 32 are deformed so as to protrude downward. From the inflection points 33 and 33 of one steel plate 32, in the center-side range A, the other steel plate 31 is in close contact with the one steel plate 32, and the electrical resistance is reduced. In the outer ranges C and C from the inflection points 33 and 33, a gap is formed between the other steel plate 31 and the one steel plate 32, and therefore, conductivity cannot be expected.
Ranges B and B in the vicinity of the inflection points 33 and 33 have intermediate properties between the ranges A and C, and the electrical resistance is much larger than the range A, although the conductivity is ensured.

すなわち、図5(a)において、点P1〜点P2にかけて主電極18の押力を、所定値まで増加する。点P2での形態が、上述した図4(a)、(b)となる。
この状態を維持しつつ、図5(b)に示す点P3で給電を開始する。
すると、図4(c)に示すように、主電極18からワーク12を通ってアース電極19、19へ電流が流れる。
That is, in FIG. 5A, the pressing force of the main electrode 18 is increased to a predetermined value from the point P1 to the point P2. The form at the point P2 is the above-described FIGS. 4 (a) and 4 (b).
While maintaining this state, power supply is started at a point P3 shown in FIG.
Then, as shown in FIG. 4C, a current flows from the main electrode 18 through the work 12 to the ground electrodes 19 and 19.

この電流は、図4(b)において、範囲C、Cでは殆ど流れない。電流は、範囲Aと、範囲B、Bに流れる。電流により、IR(I:電流値、R:抵抗値)に相当するジュール熱が発生する。範囲Aに比較して範囲B、Bが抵抗値が格段に大きいため、範囲B、Bにおいて大きなジュール熱が発生する。 This current hardly flows in the ranges C and C in FIG. The current flows in range A and ranges B and B. Joule heat corresponding to IR 2 (I: current value, R: resistance value) is generated by the current. Since the resistance values in the ranges B and B are much larger than those in the range A, a large Joule heat is generated in the ranges B and B.

このジュール熱がワークの溶融熱を超えると、超えた部位で溶融現象が発生する。すなわち、図6(a)に示すように、他方の鋼板31と一方の鋼板32との境界に、溶融池と呼ばれる溶融部34、34が出現する。この際に、他方の鋼板31が熱軟化し、主電極18の下の部位が押されて水平に流動し、一部が主電極18に沿って上へ盛り上がる。   When this Joule heat exceeds the heat of fusion of the workpiece, a melting phenomenon occurs at the excess portion. That is, as shown in FIG. 6A, melting portions 34 and 34 called molten pools appear at the boundary between the other steel plate 31 and one steel plate 32. At this time, the other steel plate 31 is heat-softened, the portion under the main electrode 18 is pushed and flows horizontally, and a part rises along the main electrode 18.

通電を停止すると、通電によるエネルギー供給が無くなるため、図6(b)に示すように、ワーク12から主電極18へ熱の移動が起こる。この現象は、主電極18がワーク12より低温であることと、ワーク12に比較して主電極18の熱容量が大きいことによって発生する。この熱の移動は、一方の鋼板32から主電極18を離すと止まる。   When the energization is stopped, the energy supply by the energization is lost, so that heat is transferred from the workpiece 12 to the main electrode 18 as shown in FIG. 6B. This phenomenon occurs because the main electrode 18 has a lower temperature than the workpiece 12 and the heat capacity of the main electrode 18 is larger than that of the workpiece 12. This heat transfer stops when the main electrode 18 is separated from one steel plate 32.

図6(c)に示すように、主電極18が一方の鋼板32から離れると、熱移動の形態が変化する。すなわち、最も高温の溶融部34、34から、より低温の周囲(一方の鋼板32及び他方の鋼板31)へ熱が移動する。この熱は液体が固体に変態するときに放出される凝固熱(又は凝集熱)に相当し、十分に大きい。溶融部34、34は凝固すると溶着部36、36になるが、溶着部36、36の近傍が凝固熱により温度上昇する。   As shown in FIG. 6C, when the main electrode 18 moves away from one steel plate 32, the form of heat transfer changes. That is, heat moves from the hottest melted portions 34, 34 to lower temperature surroundings (one steel plate 32 and the other steel plate 31). This heat corresponds to the heat of solidification (or heat of aggregation) released when the liquid transforms into a solid, and is sufficiently large. When the melted parts 34 and 34 are solidified, they become welded parts 36 and 36, but the temperature in the vicinity of the welded parts 36 and 36 rises due to the heat of solidification.

この温度上昇の形態を次図で説明する。
図7(a)、(b)は、図5(a)、(b)と同じグラフであるが、図7(c)の温度グラフの説明のために、再掲する。
図7(b)の点P3で通電が開始されると、(c)に示すように、ジュール熱により主電極近傍における一方の鋼板の温度が急増する。点P4で通電を停止すると、主電極へ熱が移動するため(図6(b)参照)、温度が下がる。この温度降下は、図7(a)に示す点P5まで続く。点P5で、押力がゼロとなり、主電極が一方の鋼板から離れる。
The form of this temperature rise will be described with reference to the next figure.
7 (a) and 7 (b) are the same graphs as FIGS. 5 (a) and 5 (b), but are re-displayed for explanation of the temperature graph of FIG. 7 (c).
When energization is started at a point P3 in FIG. 7B, as shown in FIG. 7C, the temperature of one steel plate in the vicinity of the main electrode rapidly increases due to Joule heat. When the energization is stopped at the point P4, the heat moves to the main electrode (see FIG. 6B), so the temperature decreases. This temperature drop continues to point P5 shown in FIG. At the point P5, the pressing force becomes zero, and the main electrode is separated from one steel plate.

点P5以降は、図6(c)で説明したように、凝固熱に起因して温度がδだけ上昇する。このδの大きさを確認するために、実験を行った。   After the point P5, as described in FIG. 6C, the temperature rises by δ due to the heat of solidification. An experiment was conducted to confirm the magnitude of δ.

(実験例)
本発明に係る実験例を以下に述べる。なお、本発明は実験例に限定されるものではない。
(Experimental example)
Experimental examples according to the present invention will be described below. Note that the present invention is not limited to experimental examples.

○供試材:
・一方の鋼板:厚さ0.7mm、 270MPa級亜鉛めっき鋼板
・他方の鋼板:厚さ2.0mm、 980MPa級高張力鋼板
○ Test material:
・ One steel plate: thickness 0.7 mm, 270 MPa class galvanized steel plate ・ The other steel plate: thickness 2.0 mm, 980 MPa class high strength steel plate

○抵抗溶接装置:図2による。
○温度測定:図3による。
○ Resistance welding equipment: According to FIG.
○ Temperature measurement: According to FIG.

○抵抗溶接条件:
・主電極の押力:60kg
・アース電極の押力:40kg
・電力値:5.5kA、6.5kA又は7.5kA
・通電時間:0.5秒
・通電サイクル:25回/秒
○ Resistance welding conditions:
・ Pressure of main electrode: 60kg
・ Pushing force of earth electrode: 40kg
・ Power value: 5.5 kA, 6.5 kA or 7.5 kA
・ Energization time: 0.5 seconds ・ Energization cycle: 25 times / second

○実験結果:
図8(a)に示すように、温度曲線b、c、dを得た。ただし、曲線bは電流値を7.5kAに設定し、曲線cは電流値を6.5kAに設定し、曲線dは電流値を5.5kAに設定した。
曲線bでは、δbの温度上昇が認められた。また、曲線cでは、δcの温度上昇が認められた。δcはδbの約1/3であった。また、曲線dでは温度上昇は認められなかった。
○ Experimental results:
As shown in FIG. 8A, temperature curves b, c, and d were obtained. However, the curve b set the current value to 7.5 kA, the curve c set the current value to 6.5 kA, and the curve d set the current value to 5.5 kA.
In curve b, an increase in temperature of δb was observed. Further, in curve c, an increase in temperature of δc was observed. δc was about 1/3 of δb. Further, no increase in temperature was observed in curve d.

得られた3種の供試材を切断し、切断面を観察した。
図8(b)は、曲線bに対応し、大きな溶着部36、36が認められた。
図8(c)は、曲線cに対応し、図8(b)より小さな溶着部36、36が認められた。
図8(d)は、曲線dに対応し、溶着部36、36は、極く小さかった。
The obtained three types of test materials were cut and the cut surfaces were observed.
FIG. 8B corresponds to the curve b, and large welds 36 and 36 were observed.
FIG. 8C corresponds to the curve c, and welds 36 and 36 smaller than those in FIG.
FIG. 8D corresponds to the curve d, and the welded portions 36 and 36 were extremely small.

以上の知見から、図8(a)の温度曲線b、c、dを取得し、主電極を一方の鋼板から離した直後に発生する温度上昇の有無を調べる。
曲線dでは温度上昇が認められないので、溶着部36、36は、必要な大きさに到達していないと判断できる。
Based on the above knowledge, the temperature curves b, c, and d in FIG. 8A are obtained, and the presence or absence of a temperature rise that occurs immediately after the main electrode is separated from one steel plate is examined.
Since the temperature rise is not recognized in the curve d, it can be determined that the welded portions 36 and 36 have not reached the required size.

また、曲線bでは、十分に大きな温度上昇δbが認められたので、溶着部36、36は、必要以上の大きさに到達したと判断できる。
また、曲線cでは、大きな温度上昇δcが認められたので、溶着部36、36は、必要な大きさに到達したと判断できる。
Further, in the curve b, a sufficiently large temperature rise δb was recognized, so that it can be determined that the welded portions 36 and 36 have reached a size larger than necessary.
Further, since a large temperature increase δc is recognized in the curve c, it can be determined that the welded portions 36 and 36 have reached a necessary size.

以上の知見から、主電極が一方の鋼板から離れる前から離れた後まで、主電極が当たっている若しくは当たっていた部位での一方の鋼板の温度を連続して測定する温度測定工程と、この温度測定工程で得た温度曲線b、c、dにおいて、主電極が一方の鋼板から離れた後に、温度が上昇するか否か及び温度上昇の大きさに基づいて溶着部の生成状態を判定する判定工程とからなる抵抗溶接検査方法が提供される。   From the above knowledge, from the time before the main electrode is separated from one steel plate until after it is separated, the temperature measurement step of continuously measuring the temperature of one steel plate at the site where the main electrode is hit or hit, and this In the temperature curves b, c, and d obtained in the temperature measurement process, the generation state of the welded portion is determined based on whether the temperature rises and the magnitude of the temperature rise after the main electrode is separated from the one steel plate. A resistance welding inspection method comprising a determination step is provided.

判定工程は、図3に示す判定部28で実施させるが、この判定部28に次のステップを行わせることが推奨される。
判定に先立ち、一方の鋼板及び他方の鋼板を重ね、溶接を施し、切断し、溶着部の大きさを測定し、そのときの温度差δとの相関を調べる。そして、強度的に必要な大きさの溶着部が得られたときの温度差から、しきい値Tsを定める。
このTsは、一方の鋼板と他方の鋼板の厚さの組み合わせ毎に定める。必要であれば、鋼種をパラメータに加えてTsを定める。
The determination step is performed by the determination unit 28 shown in FIG. 3, and it is recommended that the determination unit 28 perform the next step.
Prior to the determination, one steel plate and the other steel plate are overlapped, welded, cut, the size of the welded portion is measured, and the correlation with the temperature difference δ at that time is examined. Then, a threshold value Ts is determined from a temperature difference when a weld portion having a strength required is obtained.
This Ts is determined for each combination of thicknesses of one steel plate and the other steel plate. If necessary, Ts is determined by adding the steel grade to the parameters.

図9に示すように、先ず、判定部に、合格判定基準値であるしきい値Tsを入力する(ST01)。このTsは、例えば図8(a)でのδcとする。このST01は、板厚条件及び鋼種条件が変わるときにのみ実施し、変化がないときにはパスすることができる。   As shown in FIG. 9, first, a threshold value Ts, which is a pass criterion value, is input to the determination unit (ST01). This Ts is, for example, δc in FIG. This ST01 is performed only when the plate thickness condition and the steel type condition change, and can pass when there is no change.

一方の鋼板及び他方の鋼板を重ね、溶接を施し、一方の鋼板の温度を測定するが、図7(c)における点P5の温度(この温度をT1と定める。)を特定する。温度曲線を検討する時間を省く必要がある場合には、主電極上昇開始時の温度を適用してもよい(ST02)。   One steel plate and the other steel plate are overlapped, welded, and the temperature of one steel plate is measured. The temperature at point P5 in FIG. 7C (this temperature is defined as T1) is specified. When it is necessary to save the time for examining the temperature curve, the temperature at the start of the main electrode rise may be applied (ST02).

次に、n秒(例えば3秒)後までの温度曲線における最大温度T2を特定する(ST03)。ST04で、ΔT=T2−T1の演算を行う。   Next, the maximum temperature T2 in the temperature curve up to n seconds (for example, 3 seconds) is specified (ST03). In ST04, ΔT = T2−T1 is calculated.

ST05で、ΔTが正であるか否かを調べる。ゼロ又は負であれば、温度上昇が認められない。よって、溶着部なし又は微小と見なし(ST06)、不合格の判定を下す(ST07)。   In ST05, it is checked whether or not ΔT is positive. If it is zero or negative, no temperature rise is observed. Therefore, it is considered that there is no welded portion or is minute (ST06), and a failure is determined (ST07).

ΔTが正である場合、ΔTがしきい値Ts以上であるか否かを調べる。否であれば、温度上昇が認められ、溶着部の生成が予測されるが、この溶着部は小さいと見なし(ST09)、不合格の判定を下す(ST07)。   When ΔT is positive, it is checked whether ΔT is equal to or greater than a threshold value Ts. If not, an increase in temperature is recognized and the formation of a weld is predicted, but this weld is considered small (ST09) and a failure is determined (ST07).

ΔTが正で、且つTsより大きければ、十分に大きな溶着部が生成されたと予測し(ST10)、合格の判定を下す(ST11)。     If ΔT is positive and greater than Ts, it is predicted that a sufficiently large welded portion has been generated (ST10), and a pass determination is made (ST11).

以上のフローを適用すると、一方の鋼板の温度を測定するだけで、溶着部の大きさを予測することができる。非破壊検査であるから、溶接製品の全数を検査することができる。   When the above flow is applied, the size of the welded portion can be predicted only by measuring the temperature of one steel plate. Since it is a non-destructive inspection, the total number of welded products can be inspected.

尚、実施例では、2枚の鋼板を積層させたが、3枚以上の鋼板を積層させてもよい。   In the embodiment, two steel plates are laminated, but three or more steel plates may be laminated.

また、実施例では他方の鋼板31に、一方の鋼板32を載せたが、一方の鋼板32に他方の鋼板31を載せてもよい。また、板31、32を水平に配置するほか、縦向きや斜めに配置することは差し支えない。板31、32の向きに合わせて、一方の電極18及び他方の電極19、19を、上から若しくは下から又は横から一方の鋼板32へ接離させればよく、構成要素の向きは任意である。   In the embodiment, one steel plate 32 is placed on the other steel plate 31, but the other steel plate 31 may be placed on one steel plate 32. In addition, the plates 31 and 32 may be arranged horizontally or vertically or diagonally. The one electrode 18 and the other electrode 19, 19 may be brought into contact with or separated from the steel plate 32 from above, from below, or from the side in accordance with the orientation of the plates 31, 32, and the orientation of the components is arbitrary. .

本発明は、2枚の薄い鋼板を、片側スポット溶接法で接合する技術に好適である。   The present invention is suitable for a technique of joining two thin steel plates by a one-side spot welding method.

10…抵抗溶接装置、11…装置移動手段、12…ワーク、15…装置フレーム、16…主移動手段、18…主電極、19…アース電極、21…サブ移動手段、22…溶接電源、25…温度計測手段(放射温度計)、28…判定部、31…鋼板(他方の鋼板)、32…鋼板(一方の鋼板)、36…溶着部。   DESCRIPTION OF SYMBOLS 10 ... Resistance welding apparatus, 11 ... Apparatus moving means, 12 ... Work, 15 ... Apparatus frame, 16 ... Main moving means, 18 ... Main electrode, 19 ... Ground electrode, 21 ... Sub moving means, 22 ... Welding power supply, 25 ... Temperature measuring means (radiation thermometer), 28 ... determining part, 31 ... steel plate (the other steel plate), 32 ... steel plate (one steel plate), 36 ... welding part.

Claims (3)

少なくとも2枚の鋼板を積層し、一方の鋼板に主電極及びアース電極を当て、前記主電極から前記鋼板を介して前記アース電極へ通電することで、前記主電極の近傍に溶着部を生成させ、前記主電極及びアース電極を前記一方の鋼板から離す抵抗溶接作業において、前記溶着部の生成状態を検査する抵抗溶接検査方法であって、
前記主電極が前記一方の鋼板から離れる前から離れた後まで、前記主電極が当たっている若しくは当たっていた部位での前記一方の鋼板の温度を連続して測定する温度測定工程と、
この温度測定工程で得た温度曲線において、前記主電極が前記一方の鋼板から離れた後に、温度が上昇するか否か及び温度上昇の大きさに基づいて前記溶着部の生成状態を判定する判定工程とからなる抵抗溶接検査方法。
Laminating at least two steel plates, applying a main electrode and a ground electrode to one steel plate, and energizing the ground electrode from the main electrode through the steel plate, thereby generating a welded portion in the vicinity of the main electrode. In a resistance welding operation in which the main electrode and the ground electrode are separated from the one steel plate, a resistance welding inspection method for inspecting a generation state of the weld portion,
Until the main electrode is separated from the one steel plate until after it is separated, the temperature measurement step of continuously measuring the temperature of the one steel plate at the site where the main electrode is hit or hit,
In the temperature curve obtained in this temperature measurement process, after the main electrode has moved away from the one steel plate, a determination is made to determine whether or not the temperature rises and the generation state of the welded portion based on the magnitude of the temperature rise A resistance welding inspection method comprising a process.
積層した少なくとも2枚の鋼板からなるワークに対して相対移動自在に保持される装置フレームと、この装置フレームに主移動手段を介して移動自在に保持される主電極と、前記装置フレームにサブ移動手段を介して移動自在に保持されるアース電極と、前記主電極及び前記アース電極に結線される溶接電源とからなり、
一方の鋼板に前記主電極及び前記アース電極を当て、前記主電極から前記鋼板を介して前記アース電極へ通電することで、前記主電極の近傍に溶着部を生成させる抵抗溶接装置において、
この抵抗溶接装置は、前記溶着部近傍にて前記一方の鋼板の表面温度を計測する温度計測手段と、この温度計測手段から温度情報を入力すると共に前記ワークに対応するしきい値を予め取得しておき、前記主電極を前記一方の鋼板から離した直後に温度が前記しきい値以上に上昇するか否かを判定する判定部とを備えていることを特徴とする抵抗溶接装置。
A device frame held relative to a workpiece made of at least two laminated steel plates, a main electrode held movably on the device frame via a main moving means, and a sub-movement to the device frame Consisting of a ground electrode held movably through means, and a welding power source connected to the main electrode and the ground electrode,
In the resistance welding apparatus for generating a welded portion in the vicinity of the main electrode by applying the main electrode and the ground electrode to one steel plate and energizing the ground electrode from the main electrode through the steel plate,
The resistance welding apparatus includes a temperature measuring unit that measures the surface temperature of the one steel plate in the vicinity of the welded portion, and inputs temperature information from the temperature measuring unit and acquires a threshold value corresponding to the workpiece in advance. A resistance welding apparatus comprising: a determination unit that determines whether or not the temperature rises above the threshold value immediately after the main electrode is separated from the one steel plate.
前記温度計測手段は、前記一方の鋼板から放射される放射エネルギーの強さを測定し温度に変換する非接触式の放射温度計であることを特徴とする請求項2記載の抵抗溶接装置。   3. The resistance welding apparatus according to claim 2, wherein the temperature measuring means is a non-contact type radiation thermometer that measures the intensity of radiant energy radiated from the one steel plate and converts it into temperature.
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JPH0313277A (en) * 1989-06-12 1991-01-22 Nissan Motor Co Ltd Welding current control device for spot welding device
JPH0763694A (en) * 1993-08-27 1995-03-10 Hosei Brake Kogyo Kk Nondestructive inspection apparatus for spot-welded part
JPH08122051A (en) * 1994-10-21 1996-05-17 Obara Kk Method for measuring nugget of spot welding part
JP2001276980A (en) * 2000-03-30 2001-10-09 Matsushita Electric Ind Co Ltd Connecting apparatus
US20110168693A1 (en) * 2010-01-12 2011-07-14 Tubefuse Applications V.O.F Method and apparatus for determining a welding process parameter

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0313277A (en) * 1989-06-12 1991-01-22 Nissan Motor Co Ltd Welding current control device for spot welding device
JPH0763694A (en) * 1993-08-27 1995-03-10 Hosei Brake Kogyo Kk Nondestructive inspection apparatus for spot-welded part
JPH08122051A (en) * 1994-10-21 1996-05-17 Obara Kk Method for measuring nugget of spot welding part
JP2001276980A (en) * 2000-03-30 2001-10-09 Matsushita Electric Ind Co Ltd Connecting apparatus
US20110168693A1 (en) * 2010-01-12 2011-07-14 Tubefuse Applications V.O.F Method and apparatus for determining a welding process parameter

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