JP4412092B2 - Plasma welding method - Google Patents

Description

  The present invention relates to a plasma welding method for joining a plurality of workpieces using a plasma arc.

  For example, as is well known, a car body of an automobile is assembled by joining a great number of car body constituent members by welding or the like. Spot welding is often used for welding such vehicle body components. However, since the spot welding method needs to sandwich the members to be joined together with the electrodes, there are cases where the portion having a closed cross-sectional shape is not substantially applicable. Arc welding is generally used for portions where spot welding cannot be applied.

  In general, when arc welding is applied to, for example, a lap joint, plug welding is performed. When two workpieces are joined by plug welding, a hole is first drilled in advance at one joint of the workpieces to be joined. Thereafter, the workpieces to be joined are overlapped and arc welding is performed so as to fill the hole, thereby joining the workpieces. Thus, in plug welding to which the arc welding method is applied, since it is necessary to drill holes in the joint portion of the workpiece in advance as described above, man-hours are increased accordingly.

By the way, plasma arc welding, which is a type of arc welding, uses a higher temperature arc than general arc welding. When joining lap joints by plasma arc welding, drilling can be performed by superimposing plate-like joints of workpieces to be joined and irradiating a plasma arc from one of the workpieces. And after that, a filler is supplied to the hole and the workpieces are joined. As described above, when the plasma arc welding method is used, it is not necessary to drill holes in the joint portion of the workpiece in advance as in the above-described plug welding, and the number of man-hours can be reduced. Therefore, for example, by applying plasma arc welding to a lap joint portion having a closed cross-sectional shape in which no electrode can be disposed, an efficient joining operation can be performed. For example, Patent Document 1 discloses a configuration in which overlapping portions of automobile door panels are joined by plasma welding.
Japanese Patent Laid-Open No. 11-105742

  However, even when plasma arc welding is applied, when the joints of plate workpieces are overlapped and joined, if the gap between the joints is too large, the molten filler tends to flow out between the workpieces. Insufficient strength and poor appearance can occur. In addition, the spilled filler portion can be a corrosion starting point. On the other hand, if the gap between the joints is too small, the supplied filler will rise on the workpiece and the surplus height will be excessive, which may cause interference with other parts and cause poor appearance. is there.

  10A and 10B are both explanatory views schematically showing the conventional plasma arc welding method. When joining two flat workpieces W1 ′ and W2 ′ arranged parallel to each other at a predetermined interval by plasma arc welding, first, a plasma arc is directly applied to the joint portion of the upper first workpiece W1 ′. Are then drilled, and then the filler is supplied to the hole so that the first work W1 ′ and the lower second work W2 ′ are joined. As shown in FIG. 10A, when the gap between the first workpiece W1 ′ and the second workpiece W2 ′ is too large, the molten filler flows out between the workpieces W1 ′ and W2 ′. Insufficient filler and insufficient welding may result in insufficient strength and poor appearance. Further, the filler that has flowed out remains after forming the filler outflow portion 4 between the workpieces W1 'and W2', and the uneven shape of the filler outflow portion 4 can also serve as a corrosion starting point.

  On the other hand, as shown in FIG. 10B, when the gap between the first workpiece W1 ′ and the second workpiece W2 ′ is too small, the weld buildup portion 3 is excessively raised on the first workpiece W1 ′, and the surplus height is increased. If the length is too large, interference with other parts may occur or appearance may be deteriorated.

  As described above, when plasma arc welding is applied to the lap joint, the size of the gap between the workpieces and the variation thereof cause welding defects such as insufficient strength and poor appearance, thereby reducing the reliability of the weld. Such a variation in the gap between the workpieces is often caused by a variation in the size of each workpiece.

  The present invention has been made in view of the above technical problem, and can efficiently and stably join a plurality of workpieces each having a plate-like joint portion by plasma arc welding. The purpose is to do so.

  The invention according to claim 1 of the present application is a plasma welding method for joining a plurality of workpieces each having a plate-like joint using a plasma arc, and the plate-like joint to which the plasma arc is directly irradiated A first workpiece having a concave portion recessed in the plasma arc irradiation direction at the plate-like joint portion, and a bottom portion of the concave portion in a predetermined positioning state on the plate-like joint portion of the second workpiece. A step of superimposing at least the plate-like joints of the first work and the second work so as to contact each other, irradiating a plasma arc toward the concave portion in the superposed state, and supplying a filler into the concave portion And a step of filling the concave portion.

According to the invention of claim 1 of the present application, at least the concave portion is formed in the plate-like joint portion of the first workpiece, and the bottom portion of the concave portion is at least in contact with the plate-like joint portion of the second workpiece in a predetermined positioning state. Since the plate-like joints of the first workpiece and the second workpiece are overlapped, the size and variation of the gap between the workpieces can be suppressed. Therefore, when plasma arc welding is applied to the lap joint, the welding quality such as welding strength and extra-sizing size can be stabilized.
Furthermore, the side wall portion of the recess formed in the first workpiece suppresses the molten filler from flowing out between the workpieces, so that the molten filler can be easily and surely filled in the recess, and the workpieces are excellent. Can be joined.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is an enlarged cross-sectional view of a workpiece weld portion showing a plasma welding method according to Embodiment 1 of the present invention. As shown in this figure, in the first embodiment, the upper plate-shaped workpiece (first workpiece) W1 is provided with a concave portion 5 formed in advance by press molding at a predetermined position. The concave portion 5 is composed of a bottom portion 6 and a side wall portion 7, and the first bottom portion 6 is in contact with the upper surface of a lower plate-like workpiece (second workpiece) W2 in a predetermined positioning state. The workpiece W1 is overlaid on the second workpiece W2.
In this state, the welding torch 2 is arranged above the recess 5 so that the direction of plasma arc irradiation is substantially directed in the direction of depression of the recess 5. Then, by irradiating the plasma arc 1 from the welding torch 2 into the recess 5, the arc irradiated portion is drilled in the bottom 6. And after that, a molten filler is supplied in the said recessed part 5, and the 1st workpiece | work W1 and the 2nd workpiece | work W2 are joined.

FIG. 2A is a cross-sectional explanatory view schematically showing a gap and a recess depth between the first workpiece W11 and the second workpiece W12 to be joined. Here, as shown in the figure, the height from the upper surface of the plate-like first workpiece W11 to the upper surface of the bottom portion 16 of the recess 15 formed in the first workpiece W11 is defined as the recess depth H, and the recess 15 The gap between the lower surface of the bottom portion 16 and the upper surface of the second workpiece W12 is Gt, and the gap between the lower surface of the first workpiece W11 and the upper surface of the second workpiece W12 is Gn.
Therefore, in the conventional plasma welding method, the gap between the workpieces at the joint is represented by Gn. On the other hand, in the plasma welding method according to the present invention, since the recess 15 is formed in the first workpiece W11, the gap between the workpieces at the joint is represented by Gt. The gap Gt is expressed by the following formula: Gt = Gn−H.

FIG. 2B is a graph showing the variation in the gap between the workpieces at the joint when two flat workpieces are joined as in the conventional plasma welding method. In the graph of FIG. 2B, the gap Gn between the workpieces at the joint is displayed on the horizontal axis and the frequency N is displayed on the vertical axis. As shown in this figure, in the conventional plasma welding method, the variation of the gap Gn between the work at the joint will have a wider variation width E1 in the peak set value G _0.

However, the recess 15 of depth H is provided to the first work, in particular, the depth H of the concave portion 15, by setting larger than the peak value G ₀ of the variation in the gap Gn between the workpiece, a variation width smaller (Variation width: E2).

  FIG. 2C is a graph showing the variation in the gap between the workpieces according to the first embodiment of the present invention. In the graph of FIG. 2C, the gap Gt between the workpieces at the joint is displayed on the horizontal axis and the frequency N is displayed on the vertical axis. A recess 15 having a depth H is provided in the first workpiece W11. In particular, by forming the recess 15 by press molding with high dimensional accuracy, the gap between the workpieces at the joint is larger than the variation in the gap Gn between the workpieces. The variation E3 of the gap Gt can be remarkably suppressed.

Accordingly, in this state, when the workpieces are joined by plasma arc welding, the welding quality such as the welding strength and the surging size can be stabilized. Moreover, the side wall portion 17 of the recess 15 prevents the molten filler from flowing out between the workpieces, so that the molten filler can be easily and surely buried in the recess 15 and the workpieces can be joined well. Can do.
Moreover, since the said recessed part 15 is formed in the junction part of the 1st workpiece | work W11 by the side which irradiates a plasma arc, it is not necessary to perform positioning at the time of welding construction separately.

  Further, by filling the concave portion 15 with the molten filler so that the side wall portion 17 of the concave portion 15 remains, the molten filler can be reliably prevented from flowing out between the workpieces, and the workpieces are more favorable. Can be joined. In particular, since no filler outflow portion is formed between the workpieces, formation of a corrosion starting point can be suppressed.

  FIG. 3A is a cross-sectional explanatory view showing a joint after welding two plate-like workpieces. As shown in FIG. 3A, a concave portion 25 is formed in the upper first workpiece W21, and molten filler is supplied so as to fill the concave portion 25, and the first workpiece W21 and the second workpiece W22 are supplied. And are joined. Here, the diameter of the opening of the concave portion 25 is D, and the diameter of the filler solidified portion 3 (welded build-up portion) that fills the concave portion 25 by welding is Dm.

  FIG. 3B is a cross-sectional explanatory view showing a case where the diameter Dm of the filler solidified portion is too large with respect to the diameter D of the opening. As a result of various experiments, particularly when the diameter D of the opening of the concave portion 35 and the diameter Dm of the filler solidified portion 3 are D or less, the workpieces are joined by plasma arc welding. In doing so, it was found that the side wall portion 37 of the concave portion 35 formed in advance melts and the molten filler easily flows out between the workpieces, and the filler outflow suppression effect of the concave portion is reduced.

  FIG. 3C is an explanatory cross-sectional view showing a case where the diameter Dm of the filler solidified portion is too small with respect to the diameter D of the opening. In particular, when the diameter D of the opening of the recess 45 and the diameter Dm of the filler solidified portion 3 are D or more than 0.9 Dm, the filler solidified portion 3 is used when the workpieces are joined by plasma arc welding. It turned out that the notch part 8 is easy to be formed in the peripheral part.

  Therefore, it is preferable that the diameter D of the opening and the diameter Dm of the filler solidified portion 3 after welding satisfy 0.7 Dm <D <0.9 Dm. In this case, stable and good welding is performed. be able to. Accordingly, by setting the recess and the filler supply amount in this way, the sidewall portion of the recess is melted and the molten filler flows out between the workpieces, and the filler outflow suppression effect of the recess is reduced, or the filler A stable good welding can be performed without forming a notch in the peripheral edge of the solidified portion.

  Next, a second embodiment of the present invention will be described. FIG. 4 is an enlarged cross-sectional view of a workpiece weld showing a plasma welding method according to the second embodiment. In the second embodiment, the recess 55 formed in the upper first work W51 is formed by a part of a curved surface such as a spherical surface. In this case as well, variation in the gap between the workpieces can be suppressed as in the first embodiment. In addition, the side wall 57 of the concave portion 55 can obtain the molten filler outflow suppression effect, similar to the first embodiment. In FIG. 4 and subsequent figures, the filler solidified portion (welded build-up portion) when joined by plasma arc welding is indicated by a dotted line.

  FIG. 5 is an enlarged cross-sectional view of a workpiece weld portion showing a plasma welding method according to Embodiment 3 of the present invention. In the third embodiment, a substantially flat flat surface along the joining surface portion of the plate-like joining portion of the second workpiece W62 that comes into contact with the bottom portion 66 of the concave portion 65 formed in the upper first workpiece W61. The part is formed. Thereby, when joining the said workpiece | work W61 and W62 together by plasma arc welding, the joining part according to the welding strength required can be ensured more, and a side wall part is a peripheral part of the said flat part. Since it becomes difficult to melt | dissolve a side wall part by being located in, it is suppressed more that a molten filler flows out between workpiece | work, and can show | play the effect of the said Example 1 more effectively.

  Next, examples of joining three workpieces are shown in FIGS. The three workpieces are superposed together, a plasma arc is irradiated to the concave portion formed in the upper first workpiece, and a filler is supplied to the concave portion, whereby the three workpieces are joined together.

FIG. 6 is an enlarged cross-sectional view of a workpiece weld portion showing a plasma welding method according to Embodiment 4 of the present invention. In the same manner as in the above embodiments, the concave portion 105 is formed in the upper first work W101. Further, a recess 205 is also formed in the second work W102 sandwiched between the first work W101 and the lowermost third work W103. The bottom portion 206 of the concave portion 205 is overlapped with the bottom portion 106 of the concave portion 105 formed in the first work W101, so that the concave portion 205 is formed shallower than the concave portion 105, and the bottom portion 206 is the bottom portion 106. More widely formed. As shown in the drawing, the three workpieces W101, W102, and W103 are superposed on each other so as to come into contact with each other at the joint portion.
When the workpieces are joined by plasma arc welding, variation in the gap between the workpieces can be suppressed as in the first embodiment. In addition, due to the side wall 107 of the recess 105, the effect of suppressing the outflow of the molten filler can be obtained in the joining of three workpieces as in the first embodiment.

  FIG. 7 is an enlarged cross-sectional view of a workpiece weld portion showing a plasma welding method according to Embodiment 5 of the present invention. In the fifth embodiment, a recess 115 is formed in the upper first work W111, and a recess 305 is also formed in the lowermost third work W113. The recesses 115 and 305 may or may not have the same shape. The bottom 116 of the recess 115 and the bottom 306 of the recess 305 are overlapped so as to sandwich the second workpiece W112. In this state, when the three workpieces W111, W112, W113 are joined by plasma arc welding, the variation in the gap between the workpieces is suppressed, and the molten filler outflow suppression effect is suppressed as in the case of the fourth embodiment. Obtainable.

  FIG. 8 is an enlarged cross-sectional view of a workpiece weld portion showing a plasma welding method according to Embodiment 6 of the present invention. In the sixth embodiment, as shown in the drawing, the lower two plate-like workpieces, that is, the second workpiece W122 and the third workpiece W123 are joined in advance by spot welding. Another plate-like workpiece (first workpiece W121) is joined to the workpieces W122 and W123 at the spot welding portion 9. The bottom 126 of the recess 125 formed in the first workpiece W121 is superimposed on the upper surface of the second workpiece W122 on the spot welded portion 9. In this state, when the three workpieces W121, W122, and W123 are joined by plasma arc welding, the same effect as in the fourth embodiment can be obtained.

  FIG. 9 is an enlarged cross-sectional view of a workpiece weld portion showing a plasma welding method according to Embodiment 7 of the present invention. In the seventh embodiment, concave portions 135 and 215 are formed in the upper first work W131 and the lower second work W132, respectively. The concave portions 135 and 215 are disposed so as to be appropriately shifted, and the bottom portion 136 of the concave portion 135 is overlaid on the flat upper surface of the second workpiece W132. In this state, the workpieces W131 and W132 are overlaid on the third workpiece W133, whereby the gap between the first workpiece W131 and the second workpiece W132 and the gap between the second workpiece W132 and the third workpiece W133 are set at predetermined intervals. Can be set to In this state, similarly to the case of Example 4, three workpieces can be joined by performing plasma arc welding from the first workpiece side.

  In each of the above embodiments, since the workpieces to be joined may have a certain gap other than the joint portion, for example, in an automobile body, the electrodeposition liquid is applied in the electrodeposition coating process after workpiece welding. It is possible to enter between the workpieces and to obtain the effect of improving the corrosion resistance.

  In any of the above-described embodiments according to the present invention, the recess formed in the first workpiece is shown as a substantially circular spot shape in plan view, but is not limited to this, for example, in plan view Other shapes such as an oval shape may be used. Moreover, in each said Example, although it described regarding the workpiece | work which is plate shape as a whole, it is applicable also to the workpiece | work whose only junction part is plate shape. Furthermore, although the said recessed part provided in the plate-shaped junction part is formed by press molding, it is not limited to this, Other processing methods are also applicable.

  As described above, the present invention is not limited to the illustrated embodiments, and it goes without saying that various improvements and design changes can be made without departing from the spirit of the present invention.

  The method of the present invention is a plasma welding method in which a plurality of workpieces each having a plate-like joint are joined using a plasma arc, and can be applied to, for example, the welding of automobile body panels.

It is explanatory drawing which showed the plasma welding method which concerns on Example 1 of this invention. It is explanatory drawing which showed typically the gap | interval between workpiece | work, and the recessed part depth. It is the graph which showed the dispersion | variation in the clearance gap between the workpieces of the conventional plasma welding method. It is the graph which showed the dispersion | variation in the gap | interval between the workpiece | work which concerns on Example 1 of this invention. It is sectional explanatory drawing which showed the junction part after welding of a plate-shaped workpiece. It is sectional explanatory drawing which showed the case where a filler solidification part is too large with respect to the opening part of a recessed part. It is sectional explanatory drawing which showed the case where a filler solidification part is too small with respect to the opening part of a recessed part. It is sectional explanatory drawing of the workpiece welding part which showed Example 2 of this invention. It is sectional explanatory drawing of the workpiece welding part which showed Example 3 of this invention. It is sectional explanatory drawing of the workpiece welding part which showed Example 4 of this invention. It is sectional explanatory drawing of the workpiece | work welding part which showed Example 5 of this invention. It is sectional explanatory drawing of the workpiece | work welding part which showed Example 6 of this invention. It is sectional explanatory drawing of the workpiece welding part which showed Example 7 of this invention. It is explanatory drawing which showed the conventional plasma welding method typically. It is another explanatory drawing which showed the conventional plasma welding method typically.

Explanation of symbols

1 Arc 2 Welding torch 3 Filler solidified part 5, 15, 25, 55, 65, 105, 115, 125, 135 Recess 6, 16, 66, 106, 116, 126, 136 Bottom 7, 17, 57, 107, 117 Side wall W1, W11, W21, W51, W61, W101, W111, W121, W131 First work W2, W12, W22, W52, W62, W102, W112, W122, W132 Second work

Claims (1)

A plasma welding method for joining a plurality of workpieces each having a plate-like joint using a plasma arc,
Preparing a first workpiece having a plate-like joint portion that is directly irradiated with the plasma arc, and having a recess recessed in the direction of plasma arc irradiation formed in the plate-like joint portion;
Superimposing at least the first workpiece and the plate-like joint portion of the second workpiece such that the bottom of the recess contacts the plate-like joint portion of the second workpiece in a predetermined positioning state;
Irradiating a plasma arc toward the concave portion in the superposed state, supplying a filler into the concave portion, and filling the concave portion;
A plasma welding method comprising:

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