JPH044073B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a horizontal electrogas welding method in which a torch is oscillated. (Prior Art) As a conventional horizontal electrogas welding method, the method described in Japanese Patent Application Laid-Open No. 54-23049 has been proposed. FIG. 8 is a perspective view showing a situation in which the welding method is carried out, FIG. 9 is a partial sectional view seen from above, and FIG. 10 is a partial sectional view seen from the front. In Fig. 8, 1a and 1b indicate the upper base material and the lower base material, respectively, and are I-shaped or V-shaped close to I-shaped,
It shows the shaped bevel. Further, a fixed backing material 2 is in contact with the back surface of the groove, and a sliding copper stopper 4 with a shielding gas nozzle 7 is in contact with the surface of the groove. The welding wire 5 is inserted into the space formed by the welding torch 6.
The weld metal 3 is formed while swinging the tip of the welding wire 5 in the plate thickness direction, that is, in the direction of arrow E in FIG.
Horizontal electrogas welding is performed in the direction of arrow C) in the figure. The sliding copper butt 4 is water-cooled by a water supply and drainage pipe 8, and as shown in the partial cross-sectional view of FIG. arranged to form
The sliding copper butt 4 is provided with a spacing support 9 that comes into contact with the upper base material and slides together with the stationary copper butt 4. (Problems to be Solved by the Invention) However, in this conventional method, since the oscillation is a simple harmonic motion, the moving speed of the arc at the center of the oscillation is fast, as shown in the oscillation trajectory D shown in FIG. It's slow at both ends. In addition, since the cooling rate due to heat conduction of the base material is faster at the center of the plate thickness than at the front and back surfaces of the base metal, the cross-sectional shape of the weld metal 3 becomes narrower at the center of the plate thickness, as shown in FIG. The shape is constricted at the center like a drum, and there is a difference in mechanical properties between the center of the plate thickness and the ends of the plate. That is, the metal structure of the weld metal at the center of the plate thickness is finer than that at the edge of the plate, and has excellent toughness. On the other hand, the toughness at both ends of the plate is inferior to that at the center of the plate thickness, and there is a problem that a homogeneous weld cannot be obtained in the thickness direction. Furthermore, JP-A-60-191662 discusses a method of temporarily stopping the arc oscillation at the center of the plate thickness to ensure penetration at the center of the plate thickness.
Stopping the arc at one point in the center of the plate thickness has the effect of lowering the cooling rate of the weld metal at that location, but it is not effective in producing homogeneous weld metal in the thickness direction. . The present invention has been made in order to solve the above-mentioned problems of the prior art, and provides a horizontal electrogas welding method that can obtain a welded part that is homogeneous in the thickness direction of the plate. (Means for Solving the Problems) The gist of the present invention is to provide a horizontal electrogas welding method in which the welding arc is oscillated substantially in the plate thickness direction, in which the base metal is 1/3 of the base material plate thickness centered on the center of the plate thickness
The average swing speed of the arc swing within the range is lower than the average swing speed of the arc outside the range by 20% or more and 50% or less, and the minimum arc swing speed of the arc swing speed within the range. /This is a horizontal electrogas welding method characterized by setting the ratio of the maximum arc oscillation speed to 0.5 or more. The present invention will be explained in detail below. (Function) Figure 1 shows the arc swinging part, Figures 2 to 5
The figure is a diagram showing an example of an arc swing locus used in the present invention. The present invention is applied to the horizontal electrogas welding method described in FIGS. 8 to 10 above. The arc oscillation is calculated by changing the average oscillation speed of the arc in the A range of 1/3T of the plate thickness T, centered on the center of the base material plate thickness in Fig. 1, and in the Ba range and Bb range outside the A range. Lower the average swing speed of each arc within the range of 20% or more and 50% or less. The Ba range and Bb range are not particularly limited to the front side and back side of the groove, but are the arc swinging area at the edge of the plate. Further, the average swing speed within the A range is the length of the A range divided by the residence time of the arc within the A range in one way of the outward or return journey of the arc swing.
The average swing speed within the Ba range is the length of the Ba range, that is, 2 x Ba, divided by the residence time of the arc within the Ba range on both the outward and return journeys of the arc swing, and is the average swing speed within the Bb range. The average rocking speed of is also similar to the average rocking speed within the Ba range. The arc average swing speed within A range is Ba range, Bb
If the value is less than 20% of the average rocking speed within the range, there will be no effect of reducing the cooling effect in the center of the plate thickness, and the effect of improving the variation in mechanical properties in the thickness direction will not be achieved. 20%
It is necessary to lower the In addition, the arc average swing speed in the A range is in the Ba range,
If it is more than 50% lower than each average swing speed within the Bb range, the arc becomes unstable and spatter occurs frequently, so it is necessary to keep it low by keeping it below 50%. Also, since concentrating the arc at one location within the A range prevents the weld from becoming homogenized in the plate thickness direction, the minimum swing speed of the arc at each point within the A range/ It is necessary that the ratio of maximum rocking speeds be 0.5 or more. As for the arc swing trajectory, the arc average swing speed within the A range of the forward and/or return path of the welding arc swing should be 20% or more than the arc average swing speed in each range of Ba and Bb outside the A range, It is sufficient that the ratio of the minimum arc oscillation speed/maximum arc oscillation speed of the arc oscillation speed within range A is 0.5 or more, as shown in Figures 2 and 3. , one that oscillates at a constant speed in each of the A range, Ba, and Bb range of the oscillation in a reciprocating path or one-way oscillation, and as shown in Figs. 4 and 5, the oscillation range A, Ba , Bb range, the rocking speed of each point may change. In addition, if the average swinging speed of the arc in the A range is lowered by 20% or more and 50% or less than the average swinging speed of the Ba range and Bb range only in one way on the outbound or return trip, other Even if the average swing speed of the arc in the A range for one way is equal to or lower than the average swing speed in the Ba range and Bb range, Even simple harmonic motion does not prevent the weld from becoming homogeneous in the thickness direction. However, even in this case,
If the average swing speed of the arc in the A range is lower than the average swing speed in the Ba range and the Bb range by more than 50%, the arc becomes unstable. In addition, in the present invention, the number of arc oscillations is 30
If it is less than 3 times per minute, the time during which no arc blowing force is obtained at both ends of the amplitude increases, and as shown in FIG. 6, the molten metal 11 takes the lead, causing arc instability. Also, if the number of oscillations exceeds 150 times/min, the arc becomes unstable and spatter occurs frequently, which is undesirable.
The preferred range is ~150 times/min. (Example) As shown in Figure 8, one-pass welding in an I-shaped groove was performed using a sliding copper dowel on the front side and a solid backing material on the back side, and the test steel plate was SM-50B with a plate thickness of 24 mm. 1.6 mm JISYCM1 was used as the test wire, and the I-type groove with a groove gap of 13 mm was used.
Horizontal electrogas welding was performed using CO ₂ (100%) at a flow rate of 30/mm at a welding current of 380 A and a welding voltage of 31 V. The arc swing width is 20mm, the A range is 8mm, Ba,
The Bb range was 6 mm each, and the swing locus was the one shown in Figure 5. The forward movement is from the front side of the base material to the back side of the base material, and the return path is the reverse movement.The position of the welding torch 6 is determined by a linear movement type potentiometer for measuring the swing trajectory installed in the swing mechanism (not shown). was detected, and the trajectory was recorded and determined using an electromagnetic oscillograph, as shown in FIG. 5, with the vertical axis representing the swinging position of the welding torch 6 and the horizontal axis representing time. An impact test was used to determine the homogeneity of mechanical performance in the thickness direction, and the impact test pieces were measured at 2.5 mm and 6 mm from the front surface and 2.5 mm and 6 mm from the back surface as shown in Figure 7.
mm, and 2.5
Six 2 mm V-notch impact test pieces of mm width x 10 mm thickness were taken from each location, and the test was conducted at 0°C with the notch position set at the center in the width direction.
As a result, if the average impact value at each location is within a maximum variation of less than 2 kgf・m compared to other locations, it is judged as good.
Those with a variation of m or more were judged to be poor. Other welding conditions and results are shown in Table 1. Conditions Nos. 1 to 3 are examples of the present invention, and conditions Nos. 4 to 9 are comparative examples. For all conditions No. 1 to 3, the variation in average impact value was less than 2 kgf·m, and the judgment was good. Conditions No. 4 to 7 of the comparative example have a decreasing rate of arc average swing speed within the A range, and conditions No. 8 and 9 have a decrease rate of A.
The ratio of minimum swing speed/maximum swing speed of the arc within the range was outside the requirements of the present invention, and all results were judged as poor.

[Table] *1: The judgment was poor due to arc instability, and it was not possible to conduct an impact test.
(Effects of the Invention) As explained above, by using the horizontal electrogas welding method according to the present invention, it is possible to homogenize the mechanical performance in the plate thickness direction,
This is a horizontal electrogas welding method that is superior to conventional methods.

[Brief explanation of drawings]

Figure 1 is a diagram showing the arc swinging section of the present invention, Figure 2 is a diagram showing the arc swinging section of the present invention;
Figures 5 to 5 are diagrams showing examples of the arc oscillation locus of the present invention, Figure 6 is a diagram showing the molten metal level leading, Figure 7 is a diagram showing the collection position of the impact test piece, and Figure 8 is a diagram showing the horizontal A perspective view showing the gas welding method, FIG. 9 is a partial sectional view of the horizontal electrogas welding method seen from above, FIG. 10 is a partial sectional view of the horizontal electrogas welding method seen from the front, and FIG. 11 is the conventional welding method. Fig. 12 is a diagram showing the arc oscillation locus of the conventional welding method. 1a... Upper base material, 1b... Lower base material, 2... Fixed backing material, 3... Welding metal, 4... Sliding copper butt, 5... Welding wire, 6... Welding torch, 7... Shield gas nozzle, 8... Water supply and drainage Pipe, 9... Spacing support, 10... Gas escape groove, 11... Molten metal.

Claims (1)

[Claims] 1 In a horizontal electrogas welding method in which the welding arc is oscillated approximately in the plate thickness direction, the welding arc oscillation is performed within a range of 1/3 of the base material plate thickness around the center of the base material plate thickness in the forward and/or return path of the welding arc oscillation. The average swing speed of the arc swing should be lower than the average arc swing speed outside the range by 20% or more and 50% or less, and the minimum arc swing speed/maximum arc swing speed of the arc swing speed within the range should be lowered. A horizontal electrogas welding method characterized by a dynamic speed ratio of 0.5 or more.