JPS6332551B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method in which the feed position and direction of filler wire can be accurately regulated when performing electron beam welding while feeding filler wire, thereby making it possible to improve joint performance and bead appearance. be. Since the electron beam has an extremely high energy density, even thick workpieces can be welded all at once by simply butting the I-shaped grooves together without creating a groove-shaped groove. Therefore, it has become standard practice to perform welding without using filler wire. However, in order to perform such non-filler welding without any problems, it is necessary to improve the bevel precision. If the bevel precision is low or a gap occurs, there will be a lack of molten metal, resulting in cavity defects and depressions (underfill) on the bead surface. etc. occur. However, if the shortage of molten metal is made up by supplying filler wire, the above-mentioned defects can be prevented.Furthermore, by adjusting the composition of the weld metal using filler wire, the machine of the joint can be improved. It also becomes possible to increase the strength of the target. This method of performing electron beam welding while feeding filler wire is extremely effective in improving the soundness and quality of the weld, but on the other hand, if the feeding direction of the filler wire to the bead hole fluctuates, the melting rate becomes unstable. If the groove becomes uniform, cavity defects will occur, and if the insertion depth in the groove depth direction is insufficient, problems will occur such as the components of the weld metal becoming non-uniform in the depth direction. To deal with this problem, electron beam welding is performed while continuously supplying flux-cored wire to the molten metal, and by covering the surface of the molten metal with slag, the undercut at the weld toe and the surface of the bead are removed. How to prevent roughness (Special Publication No. 46-43967)
(Japanese Patent Publication No. 46-43968), a method for preventing cavity defects and bead surface defects by supplying a tubular wire containing a deoxidizing element to the molten metal to remove oxygen in the molten metal (Japanese Patent Publication No. 46-43968); A method has been proposed in which a wire guide groove is provided in the upper part of the groove of the base material facing the electron gun, and electron beam welding is performed while supplying filler wire along the guide groove (Japanese Patent Laid-Open No. 52-29444). ing. However, the above-mentioned methods cannot prevent the above-mentioned defects caused by unstable wire feeding, and the method requires complicated bevel processing and also causes problems such as twisting and curling of the wire. It is not possible to prevent the tip from rolling. Under the above-mentioned circumstances, the inventors of the present invention began research with the aim of establishing a method that would enable the filler wire to be accurately supplied to the appropriate position of the electron beam hole (without causing sideways movement, etc.). did. As a result, the following facts were confirmed. That is, as shown in FIG. 1 (explanatory cross-sectional view), when electron beam welding a thick steel plate 1 in a horizontal position while supplying a filler wire 2, the supply position of the filler wire 2 (melted by the electron beam A) If the filler wire is located close to the surface of the base material, it becomes difficult for the molten metal from the filler wire to diffuse deep into the groove, and it also tends to drip from the groove surface. On the other hand, if the filler wire 2 is fed deep into the groove as shown in Fig. 2 (explanatory cross-sectional view), the above problem is solved, but the filler wire 2 tends to come into contact with the molten metal near the groove surface. , the feed becomes unstable and the bead shape becomes disordered, and welding may have to be interrupted.
In addition, the feed position of the filler wire 2 must always be at the center of the electron beam A. For example, as shown in FIG. If the wire 2 deviates from the center of the hole, the wire 2 will not melt and will stick into the hole wall, making welding impossible. By the way, as a normal filler wire feeding method, as shown in FIG. A method is adopted in which the material is fed to the welding part while regulating its direction. In this case, the unwinding position of the wire 2 changes over time in the width direction and the winding thickness direction of the spool 3, and the degree of winding of the wire 2 is different between the winding start position and the winding end position. The twisting state of the wire 2 changes slightly, giving the wire 2 an irregular bend, and the tip of the wire 2 coming out of the wire guide 5 swings as shown in FIG. As a result, as shown in FIG. 2, when the wire 2 is fed into the deep part of the groove, it is easier to contact the molten metal, and as shown in FIG. 3, the wire 2 can be directed toward the center of the electron beam A. This can lead to problems such as those mentioned above. The inventors of the present invention have focused on the above-mentioned circumstances and have conducted intensive research in order to establish a method that can accurately supply the filler wire to the center position of the electron beam deep within the groove. As a result, if the irregularities that occur during the wire feeding process are corrected, swinging of the wire tip can be prevented, and the filler wire can be given a new bend with a curvature that approaches the molten metal surface. It was confirmed that contact with molten metal could be suppressed, and as a result of further research, the present invention was achieved. That is, in the electron beam welding method according to the present invention, when performing electron beam welding while feeding a filler wire into a narrow gap, the approach angle of the wire to the opposing roll for wire feeding is set to a common angle of the opposing rolls. Set at 5 degrees or more with respect to the tangential direction,
The gist is that welding is performed by feeding the wire while winding it around at least one grooved roll provided in front and/or behind the opposing roll. The structure and effects of the present invention will be explained below based on the drawings showing examples, but the following are examples and do not limit the present invention, and the following is an example and does not limit the present invention. All modifications are within the scope of the present technology. 5 and 6 are a schematic plan view and a schematic side view showing an embodiment of the present invention. After the filler wire 2 wound around the spool 3 is once wound around the grooved roll 6, 4, 4 so as to feed the wire in the direction of the wire guide 5. When the wire 2 is wound at least once around the grooved roll 6 in this way, the feeding position in the direction of the opposing feeding rolls 4 and 4 is specified at this portion, and also the unwinding due to fluctuations in the feeding position of the spool 3 is avoided. Regular bends are corrected, and swinging of the wire tip is drastically reduced. Furthermore, the present inventors have confirmed through experiments that although the winding on the grooved roll 6 can correct the bending in the width direction of the spool winding, the bending in one direction with respect to the wire 2 For the purpose of creating curls, the grooved roll 6 alone was still insufficient.
However, as shown in FIG. 7, if the entrance angle θ of the wire 2 with respect to the opposing rolls 4, 4 (the angle between the common tangent S of the opposing rolls 4, 4 and the wire entry direction) θ is properly adjusted, the wire 2 can be It was found that it is possible to give a curved shape. For example, in the ninth example, the approach angle θ of the wire 2 with respect to the opposed drive rolls 4, 4 was variously changed using the method shown in FIG. The graph shown in the figure shows that the wire 2 can be bent sufficiently in one direction by setting the approach angle θ to 5 degrees or more, although it differs slightly depending on the wire diameter.
Moreover, by adjusting the approach angle θ, the degree of bending (radius of curvature) can be freely adjusted, so that the optimum radius of curvature can be obtained according to the degree of curvature of the molten metal surface, as will be described later. In addition, in this experiment, we confirmed the lateral oscillation of the wire tip (oscillation width W shown in Figure 10), and found that in the conventional method in which the grooved roll 6 was omitted, the oscillation width was 3.8 mm. It was confirmed that the swing width W was reduced to 1.3 mm by simply arranging the grooved roll 6 and winding it once. Since the beam diameter generally employed in electron beam welding is about 2 mm, it is understood that the above correction can almost certainly prevent the wire 2 from coming off the beam A. Therefore, if the filler wire is fed by the above method, the filler wire 2 can be smoothly inserted deep into the groove along the surface of the molten metal, as shown in FIG. 11 (explanatory cross-sectional view). The above-mentioned problems caused by contact with molten metal can be prevented. Moreover, as shown in FIG. 12 (a view of the welded part seen from above the groove), it becomes possible to direct the filler wire 2 almost to the center of the electron beam A. As described above, in the present invention, by winding the wire around the grooved roller 6 to correct irregular bending, the swinging of the wire tip is reduced, and the approach angle to the counter-driving rolls 4 is set to 5 degrees or more. The biggest feature is that the wire can be inserted into the deep part of the groove smoothly by setting the wire to an appropriate curvature. Various modifications are possible. For example, FIGS. 13 and 14 are a schematic plan view and a schematic side view showing another embodiment of the present invention, in which the grooved roll 6
a and 6b are arranged so that their respective axes are perpendicular to each other, and are configured so that they can be straightened twice in the horizontal and vertical directions.In this way, two or three or more grooved rolls are used. This will further enhance the correction effect. Further, FIG. 15 (schematic side view) shows an example in which the approach angle θ can be adjusted by a guide roll 7, and a grooved roll 6 is provided behind the opposing drive rolls 4, 4 to enable correction. In this case, since it is necessary to provide a large number of presser rolls 8 and the like around the outer periphery of the grooved roll 6, the structure of the straightening section becomes somewhat complicated, but the straightening effect itself is almost the same as in the above-mentioned example. The present invention is roughly constructed as described above, and its effects can be summarized as follows. Since irregular bends are corrected using grooved rolls, there is very little swinging of the wire tip, and smooth welding can be performed without the wire coming off the electron beam. By setting the wire entry angle to 5 degrees or more with respect to the common tangential direction of the opposing rolls, it is possible to give the wire an appropriate bend, allowing it to be inserted into the groove deep along the surface of the molten metal without any trouble. can do. In addition, the radius of curvature of the wire can be adjusted arbitrarily by appropriately changing the entry angle within a range of 5 degrees or more, making it easy to find the optimal insertion depth according to the thickness of the base material, welding conditions, etc. Can be secured. Due to the above effects, the transition state of molten metal from the wire becomes extremely smooth, and a beautiful welded joint without internal defects can be obtained. Moreover, dripping of molten metal from the groove surface does not occur, and the composition of the weld metal can be uniformly adjusted by the filler wire. As a feeding device, it is only necessary to attach a grooved roll or this and a guide roll (Fig. 15) to a conventional device, and it can be easily applied to existing devices, and even if it is newly installed, the cost burden is extremely low. Minor. Next, examples of the present invention will be shown. EXAMPLE Mild steel plates having a thickness of 70 mm were butted together with a gap of 1.5 mm, and electron beam welding was performed while feeding filler wire according to the method shown in FIGS. The compositions of the mild steel plate and filler wire used are shown in Table 1, and the welding conditions are shown in Table 2. The approach angle (θ) to the opposing roll was 2 degrees, 5 degrees, and 10 degrees. For comparison, a welding experiment was conducted in the same manner as above except that the grooved roll was omitted.

【table】

[Table] As a result, in the comparative method that omitted the grooved roll, the wire could not be inserted deep into the groove because it would come into contact with the molten metal and the feeding would become unstable, and the wire tip would not swing. As a result, the wire often deviated from the center of the beam, resulting in extremely poor welding workability. Moreover, since the wire could only be inserted to the shallow part of the groove, molten metal dripped down. In addition, when a grooved roll was used and the entrance angle was set to 2 degrees, the straightening effect at the grooved roll part prevented the tip of the wire from swinging, but it was difficult to bend the wire with a sufficient radius of curvature. This made it difficult to insert the metal deep into the groove, and it was not possible to prevent the molten metal from dripping. For these, a grooved roll is used to increase the approach angle to 5 degrees and
When set to 10 degrees, the wire can be bent with a sufficient radius of curvature and can be inserted deep into the groove, eliminating dripping of molten metal.
The straightening effect also prevented the wire tip from swinging, making welding extremely smooth. In addition, in order to confirm the distribution state of alloy components for each welded joint obtained above,
Focusing on Cr, the content in the groove depth direction of each welded joint was investigated. The results are shown in Table 3.

[Table] As is clear from Table 3, in both the comparative method and the method in which the wire entry angle is set to 2 degrees, the wire cannot be inserted deep into the groove. As a result, the alloy component concentration on the back side is extremely low. On the other hand, if the wire entry angle is set to 5 degrees or more, the wire can be inserted deep into the groove, allowing sufficient diffusion of the alloy components and reducing the variation in the composite component concentration between the front and back sides. .

[Brief explanation of the drawing]

1 to 3 show an example of conventional electron beam welding using filler wire, FIGS. 1 and 2 are schematic cross-sectional explanatory views, and FIG. 3 is a view seen from the groove surface side. FIG. 4 is a schematic diagram showing a conventional filler wire feeding method. Figure 5 and subsequent figures show embodiments of the present invention, with Figures 5 to 8 being schematic explanatory diagrams, and Figure 9 being a schematic explanatory diagram.
The figure is a graph showing the relationship between the wire approach angle with respect to the opposing roll and the radius of curvature given to the wire.
Figure 0 is an explanatory diagram showing the method for measuring the swing width of the wire tip.
Figures 11 and 12 are cross-sectional explanatory diagrams showing welding conditions according to the present invention, views seen from the groove surface side, and Figures 13 to 1.
FIG. 5 is a schematic explanatory diagram showing another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Base material, 2... Filler wire, 3... Spool, 4... Opposing roll for feeding, 5... Wire guide, 6... Grooved roll, 7... Guide roll, 8... Pressing roll, A...Electron beam.

Claims (1)

[Claims] 1. When performing electron beam welding while feeding the filler wire into the narrow gap, the approach angle of the wire to the opposing roll for wire feeding is set to 5 degrees or more with respect to the common tangential direction of the opposing rolls. Further, an electron beam welding method characterized in that welding is performed by feeding the wire while winding it around at least one grooved roll provided in front and/or behind the opposing roll.