JP2014091126A - Arc welding process - Google Patents

Abstract

PROBLEM TO BE SOLVED: To promptly secure a certain build-up amount and realize prevention of undercutting and burnout and improvement of production efficiency.SOLUTION: The arc welding process for jointing a face 2a of one steel plate 2 to an end 1a of the other steel plate 1 by arc welding using an arc torch 4, performs: a wire feeding step of arranging a welding wire 3' in a gap 5 formed at a butting part of the face 2a of the one steel plate 2 and the end 1a of the other steel plate 1; and an arc welding step of arc welding the butting part in which the welding wire 3 is arranged.

Description

  The present invention, when arc welding thin plates such as body steel plates of an automobile, can prevent undercut and burn-off and increase the welding work speed even when there is a gap between the thin steel plates. The present invention relates to an arc welding method.

  As is well known, an automobile body is constituted by joining a plurality of steel plates by welding. As the welding method, spot welding is generally employed from the viewpoint of cost and productivity, and most of the welds are formed by spot welding. However, spot welding is a method of forming a welded portion by sandwiching a steel plate with a pair of electrodes. Therefore, welding cannot be applied to a portion where the steel plate cannot be sandwiched, and some of the portion where the welded portion is formed There is a limit. Therefore, arc welding is used instead of spot welding for such parts. Arc welding is a method of joining by melting a wire as a steel plate or an electrode bar with high heat caused by an arc generated between the steel plate and an electrode.

  By the way, when an arc is applied to a thin steel plate having a thickness of several millimeters constituting an automobile body, a part of the steel plate may be melted by arc heat during welding. When such a burn-out occurs, there is a problem that the worker has to perform welding manually and repair it, which impairs the significance of the automated line. When the welding current is increased, the melt-off is likely to occur because the arc heat becomes higher. For this reason, some measures can be taken by changing the welding conditions such as performing welding by lowering the current value, but there is also a problem that the welding speed is lowered and workability is deteriorated.

  Further, as described above, since the body of an automobile is composed of a plurality of steel plates, the size of the gap between the steel plates varies as the assembly proceeds. 11 and 12 show a case where arc welding is performed in a conventional part having such a gap. As shown in FIG. 11, the thin steel plates 1 and 2 are arranged in a T-shaped cross section, and an arc is generated while a wire 3 as an electrode rod is fed from the torch 4. Thereby, while the thin steel plates 1 and 2 facing the gap 5 are melted, the wire 3 is also melted to form a three-part alloy portion 6 (see FIG. 12).

  In this case, it is necessary to fill the gap 5 by securing a sufficient amount of build-up with molten metal. However, when arc welding is performed on a thin plate, it is necessary to consider melting as described above, and thus the current value cannot be increased unnecessarily. Also, the molten metal (alloy 6) tends to flow out from the gap 5 to the side opposite to the side where the torch 4 is present (left side in FIG. 12). For this reason, the amount of build-up is insufficient, and the melted portions 1 a ′ and 2 a ′ of the thin steel plates 1 and 2 which are the base materials cannot be filled, and a recess (under) is formed between the melted portions 1 a ′ and 2 a ′ Cut 7) was sometimes formed. The undercut 7 has a problem of strength such as stress concentration and causing cracks and fractures.

  For example, in the technique shown in Patent Document 1, a stud having a projecting surface at the tip is attached to an electrode of an arc welder, and the tip of the stud is brought close to two members to be welded with a gap. Yes. Then, an arc is blown from the projection surface of the tip portion to the two welded members, and the respective welded portions and the surface portions of the projection surfaces are welded. Further, the gap between the welded parts is filled with the unmelted portion of the projection surface. That is, in the technique of Patent Document 1, the welding work time is compared with the case where the gap between the welded portions is filled with the unmelted portion of the tip protrusion surface of the stud, as compared with the case where the gap is filled with a molten member such as a wire. Is shortened to prevent melting.

JP-A-9-285865

  However, the technique shown in Patent Document 1 can be applied to the case where welding is performed in the form of dots, but for a case in which thin steel plates are arranged in a T shape and a gap is formed in a linear shape. In the case of continuous arc welding, it could not be adopted.

  The present invention has been improved and removed in view of the above-mentioned problems, and ensures a certain amount of build-up at an early stage, thereby preventing burn-out and undercut, and improving welding speed. It is intended to provide an arc welding method that can be performed.

  The means employed by the present invention to solve the above problems is an arc welding method in which the surface of one steel plate and the end of the other steel plate are joined by arc welding using an arc torch, wherein the one steel plate A wire supplying step of disposing a welding wire in a gap formed at a butt portion between the surface portion of the steel plate and the end of the other steel plate, and an arc welding step of performing arc welding on the butt portion where the welding wire is disposed And have.

  As described above, in the arc welding method according to the present invention, the wire is previously disposed in the gap formed in the butt portion between the thin steel plates, and then the arc welding is performed on the butt portion. When the arc welding operation is performed, the wire that is drawn from the torch and melts during arc welding and the base material of the thin steel plate are melted. Since this molten metal is dammed up by the wire previously arranged, outflow from the gap to the outside (the side opposite to the side where the arc torch is arranged) is suppressed. Among them, the wires arranged in advance are also melted and united together to form a weld overlay.

  As described above, since the flow of molten metal to the outside from the gap is suppressed by the wire arranged in advance, the molten metal can be kept near the gap. In addition, when the wire arranged in advance is melted and fused with the base material, the build-up amount of the welding itself increases. Therefore, the recessed part formed in the thin steel plate can be reliably filled with the molten metal, and the occurrence of undercut can be prevented. In the past, in order to secure a certain amount of build-up, the amount of wire melted from the torch had to be increased, and only slow welding was possible, leading to a decrease in productivity. In the invention, the wire previously disposed near the gap and the wire fed from the torch can be melted by one-time arc welding. As a result, when a build-up amount of a certain level or more is secured, the welding speed can be increased and the welding work can be advanced, and arc welding with excellent work efficiency can be realized.

  In the wire supply process, if the center of the welding wire is arranged on the side of the gap where the arc torch is not arranged with respect to the central portion in the thickness direction of the other steel plate, the entire area of the gap is filled with molten metal. It becomes easy and the joint strength of the welded portion is improved.

  According to the present invention, the welding operation can be performed without generating an undercut and a burn-out by previously arranging the wire so as to fill the gaps in the welding site, and reducing the welding speed. Arc welding work with high production efficiency is possible.

It is a longitudinal cross-sectional front view of the butt | matching part of thin steel plates which shows the wire supply process of the arc welding method which concerns on one Embodiment of the arc welding method of this invention. It is a longitudinal cross-sectional side view of the butt | matching part of thin steel plates which shows the said wire supply process. It is a longitudinal cross-sectional side view of the butt | matching part of thin steel plates which shows the state which the said wire supply completed. It is a longitudinal cross-sectional front view of the butt | matching part of thin steel plates which shows the arc welding process of the said arc welding method. It is a longitudinal cross-sectional front view of the butt | matching part of thin steel plates which shows the state welded by the said arc welding method. It is a longitudinal cross-sectional side view of the welding part of thin steel plates which shows the arc welding process which concerns on other embodiment of the arc welding method of this invention. It is a longitudinal cross-sectional side view of the welding part of thin steel plates which shows the arc welding process which concerns on other embodiment of the arc welding method of this invention. FIG. 8 is a plan view of FIG. 7. It is a front view which shows the welding part of the sheet steel plate and pipe which concern on other embodiment of the arc welding method of this invention. It is sectional drawing in the CC line of FIG. It is the conventional arc welding method, Comprising: It is a longitudinal cross-sectional view of the welding part of the thin steel plates which shows the state before a welding operation start. It is the conventional arc welding method, Comprising: It is a longitudinal cross-sectional view of the welding part of the thin steel plates which shows the state in the middle of welding operation.

  Hereinafter, an embodiment of the arc welding method of the present invention will be described with reference to FIGS. 1 and 2. In this embodiment, the thin plate 1 and the thin plate 2 are butted in a T shape and welded. The arc welding method of the present invention comprises two steps, a “wire supply step” and an “arc welding step”.

  First, in the “wire supply process”, a wire (welding rod) 3 is disposed in a gap 5 formed between a steel plate end 1 a of the thin plate 1 and a surface portion 2 a of the thin plate 2. The wire 3 may be supplied from the existing arc torch 4 serving as a welding tool, and does not require a separate dedicated machine tool device. In other words, it does not cause an increase in the size of the equipment. Note that the wire supplied from the torch 4 in the wire supply process is denoted by reference numeral 3 'for convenience of explanation.

  The wire supply process will be specifically described. First, as shown in FIG. 1, the tip 3 a ′ of the wire 3 ′ fed out from the torch 4 is inserted into the gap 5 formed at the butt portion between the thin plate 1 and the thin plate 2. insert. In the present embodiment, the center of the wire (welding rod) 8 is located on the opposite side (left side in the figure) to the side where the arc torch 4 is disposed with respect to the central portion in the thickness direction of the thin plate 1 in the gap 5. Arrange. In this state, a weak current is supplied from the torch 4 to weld and fix the tip 3a 'of the supplied wire 3' and the thin plate 2 (the welded portion of the wire tip 3a 'is indicated by Q1). In this case, the current value is only temporarily fixed so that the wire 3 ′ does not move between the thin plates 1 and 2, and it is not necessary to melt the wire 3 ′ and the thin plates 1 and 2. A weaker current is sufficient than when welding.

  Next, as shown in FIG. 2, the wire 3, whose tip 3 a ′ is fixed to the thin plate 2, is moved by moving the torch 4 along the abutting portion while feeding the wire 3 ′ from the torch 4. Can be disposed along. When the wire 3 ′ is arranged over the entire length of the gap 5, the wire 3 ′ and the thin plate 2 are welded and fixed by passing a weak current from the torch 4 as in the case of the tip 3 a ′. Cut the wire 3 'in position. Thereby, as shown in FIG. 3, the wire 3 ′ is disposed along the gap 5, and the front end portion 3 a ′ and the rear end portion 3 b ′ are welded to the thin plate 2 (welding of the wire rear end portion 3 b ′). Part is indicated by Q2.). If necessary, temporary fixing welding may be performed in one or several places between the front end portion 3a 'and the rear end portion 3b' of the wire 3 'by the same method as described above. Thereby, it is possible to arrange | position wire 3 'over the whole site | part where the thin steel plates 1 and 2 collide in T shape, and wire 3' displaces at the time of the arc welding performed next. There is no waking.

  Thereafter, the process proceeds to the welding process shown in FIG. Welding is performed while the wire 3 is unwound from the same torch 4 as in the wire supply step and an arc is generated. Thereby, first, the thin plates 1 and 2 and the wire 3 fed out from the torch 4 are melted to fill the gap 5. At this time, these molten metals are prevented from flowing out from the gap 5 by the wire 3 ′ previously disposed in the gap 5. Then, the wire 3 previously disposed in the gap 5 also melts, and the wire 3 fed out from these torches 4 and the thin steel plates 1 and 2 as the base material are disposed in advance. The gap 5 is filled with the alloy 6 that is fused and integrated with the wire 3 ′. Arc welding requires a certain amount of build-up, but in this embodiment, the wire 3 'is previously disposed and fused, so that a certain amount of build-up necessary for welding is generated in a short time. be able to. For this reason, the arc time in the unit portion can be shortened, and it is possible to prevent the melt-off and to increase the welding speed. As described above, by arranging the wire 3 ′ in the gap 5 in advance, it is possible to prevent the molten metal from flowing out from the gap 5 to the outside and increase the build-up amount. It is possible to reliably fill the melted portion with the alloy 6 to prevent undercut.

  The present invention is not limited to the above embodiment. For example, as exaggeratedly shown in FIGS. 6 and 7, the size of the gap 5 may vary depending on the location because the steel plate 2 is curved. In this case, a detection unit for detecting the gap 5 between the thin plates 1 and 2 is provided (not shown), the size of the gap 5 is detected by the detection unit before the wire supplying step, and the size of the gap 5 is constant. You may make it arrange | position wire 3 'only about the site | part which is the above (refer FIG. 6). Alternatively, as shown in FIGS. 7 and 8, the wire 3 ′ is disposed over the entire length of the abutting portion, and the wire 3 ′ enters the gap 5 in a place where the size of the gap 5 is larger than the diameter of the wire 3 ′. Alternatively, the wire 3 ′ may be disposed at the corner of the butted portion of the thin plates 1 and 2 in a place where the size of the gap 5 is equal to or smaller than the diameter of the wire 3 ′. In this case, the cross section taken along the line AA in FIG. 8 is the same as the embodiment shown in FIG. 4, and the cross section taken along the line BB in FIG. 8 has the wires 3 ′ arranged at the corners formed by the thin plates 1 and 2. It will be in the state (illustration omitted).

  When the gap is large, it is necessary to melt the wire 3 to form a predetermined amount of build-up, but by preliminarily arranging the wire 3 ′, the gap is filled with the wire 3 ′ so that the build-up can be performed early. It is easy to realize. In addition, with respect to a portion having little or no gap, sufficient arc welding can be realized only by building up the wire 3 that is drawn from the torch 4 and melted during welding. If there is a portion that does not require the wire supply process, it is possible to shorten the welding work time, and it is determined whether or not the wire 3 ′ is supplied in advance, and the wire 3 ′ is supplied only for the necessary portion. Thus, it is possible to realize arc welding work with good production efficiency as a whole.

  The embodiment shown in FIG. 9 shows a case where the thin steel plate 8 and the pipe 9 are arc-welded. In this case, the welded part is a part where the outer peripheral surface of the pipe 9 and the thin steel plate 8 abut, and in the wire supplying process, the gap 5 between the end of the thin steel plate 8 and the outer peripheral surface of the pipe 9 is A wire 3 ′ is disposed (see FIG. 10). The procedure of other wire supply processes and arc welding processes is the same as that in the above embodiment.

  In the above embodiment, the case where the thin plates 1 and 2 are welded to each other in a T-shape (the thin plate 1 stands up in a 90-degree direction with respect to one thin steel plate 2) is shown. Butt welding at an angle may also be used. The wire 3 'disposed in the gap 5 is centered on the opposite side (left side in FIGS. 4 and 11) to the side where the arc torch 4 is disposed with respect to the central portion in the thickness direction of the thin plate 1. However, it may be on the arc torch 4 side or in the center of the gap 5. Furthermore, welding was started after a weak current was applied to the thin steel plates 1 and 2 by passing a weak current through the front end and the rear end of the wire 3 ′, but a separate temporary fixing means was provided. It is also possible to omit the temporary welding.

DESCRIPTION OF SYMBOLS 1 Sheet steel plate 2 Sheet steel plate 3 Wire 3 'Wire previously arrange | positioned 4 Arc torch 5 Crevice 6 Alloy part

Claims (2)

An arc welding method in which a surface portion of one steel plate and an end portion of the other steel plate are joined by arc welding using an arc torch,
A wire supplying step of disposing a welding wire in a gap formed between a surface portion of the one steel plate and an end portion of the other steel plate; and arc welding to the abutting portion where the welding wire is disposed An arc welding method having an arc welding process to be applied.   2. The arc according to claim 1, wherein, in the wire supplying step, a center of the welding wire is disposed on a side where the arc torch is not disposed with respect to a central portion in the thickness direction of the other steel plate in the gap. Welding method.

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