JPH046472B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to an improvement in a horizontal electrogas welding method that completes welding in one pass and one run. (Prior art) As one of the highly efficient horizontal welding methods, Japanese Patent Application Laid-Open No. 54-23049 discloses a narrow gap horizontal automatic welding method, i.e., a horizontal electrogas welding method shown in FIGS. 4 and 5. Welding methods have been proposed. FIG. 4 is a perspective view showing a state in which the welding method is being carried out, and FIG. 5 is a partial sectional view of the front side thereof. In Fig. 4, 1 and 2 are the upper base material, respectively;
The lower base material is shown, and the I-shape or V-shape or V-shape groove close to the I-shape is shown. Further, a fixed backing material 3 is in contact with the back surface of the groove, and a sliding copper stopper 4 with a shield nozzle is in contact with the surface of the groove.
Note that a sliding copper pad may be used on the back surface instead of the fixed backing material. Insert the welding wire 5 through the flattened tip 6 into the space formed by these, and place the tip of the welding wire at an angle of 0 to 5 degrees with respect to the groove surface of the lower plate and with respect to the back surface of the base metal. , aim at an angle of 0 to 10 degrees, and point the tip of the welding wire in the plate thickness direction, that is, arrow A in Fig. 4.
The weld metal 7 is formed while swinging in the direction of , and the groove is welded in one pass and one run. At this time, a welding cart (not shown) on which the sliding copper dowel 4, the chip 6, etc. are mounted is placed between the chip 6 shown in FIG. Changes in the inter-plane distance P are detected as changes in the welding current, and the cart runs automatically while controlling speed to keep P constant. Although the above welding method is a highly efficient welding method that can perform horizontal welding in one pass and one run, depending on the welding conditions, as shown in FIG. As shown in FIG. 7, poor penetration 10 on the upper base metal side is likely to occur, and the welding is not necessarily stable.
In particular, when welding a long welding length exceeding 3 m, this tendency becomes more pronounced as the welding length becomes longer. (Problems to be Solved by the Invention) In view of the above problems, the present inventors investigated various welding conditions and found a relationship between the above problems and welding conditions. Therefore, it is an object of the present invention to provide a horizontal electrogas welding method that allows stable welding at all times, even in long welding, by specifying welding conditions, without causing molten metal level advance or insufficient penetration on the upper base metal side. It is said that (Means for Solving Problems) The gist of the present invention is to form an upper base material and a lower base material into an I-shape, a V-shape close to an I-shape, or a V-shape groove, and A fixed backing material or a sliding copper backing is brought into contact with the groove surface, and a sliding copper butting is brought into contact with the groove surface, and the groove surface and the fixed backing material or sliding copper backing,
The welding wire is inserted through the flat tip into the space formed by the sliding copper butt, and the tip of the welding wire is swung in the direction of the plate thickness, causing the trolley to run.
In the horizontal electrogas welding method in which the groove is welded in one pass and one run using a welding cart that automatically moves while detecting the welding current,
Using ~1.7mm solid wire, the thickness of the upper base material
In relation to T _A (unit: mm) and the plate thickness T _B (unit: mm) of the lower base material, set the welding speed V (unit: cm/min) between the lower limit value Va and the upper limit value Vb that satisfy the following formula Va ≦V≦Vb Here, the wire feeding speed is adjusted so that Va=3201/T _A +T _B −1.5 Vb=3201/T _A +T _B +1.0, and the wire feeding speed W (unit: m /min), set the welding current I (unit A) between the lower limit Ia and upper limit Ib that satisfy the following formula, Ia≦I≦Ib, where Ia=20W+160 Ib=20W+200. and set the welding voltage E (unit: V) for the welding current I (unit: A).
Set the welding voltage E between the lower limit value Ea and upper limit value Eb that satisfies the following formula: Ea≦E≦Eb, where Ea=1.147I ^0.55 −1 Eb=1.147I ^0.55 +1 The horizontal electrogas welding method is characterized by: (Function) In the state shown in Fig. 4, the plate thickness T _A + T _B and the groove gap G are varied to obtain good welding results under the welding conditions, and due to the advance of molten metal,
The relationship between the state where a welding defect occurs and the state where a penetration defect occurs on the upper base metal side is determined by 3.
The investigation was carried out using test specimens with a weld length of m to 5 m. As a result, between welding speed V and plate thickness T _A + T _B ,
We found a certain correlation. The relationship is shown in FIG. In Fig. 1, the range A between curves a and b indicates the appropriate range, and the welding speeds Va and Vb (unit: cm/min) and plate thickness T _A + corresponding to these curves a and b.
The relationship with T _B (unit: mm) can be found from the figure as follows. Va=3201/T _A +T _B -1.5...(1) Vb=3201/T _A +T _B +1...(2) Therefore, the appropriate welding speed has the relationship Va≦V≦Vb...(3). Note that B and C indicate inappropriate areas, B is a range where molten metal precedes and causes welding defects, and C is a range where poor welding occurs on the upper base metal side. In order to perform stable welding,
Once the plate thickness T _A + T _B is determined, the welding speed can be adjusted so as to comply with the above equations (1) to (3). By the way, as explained in Fig. 4, this welding method is a one-pass, one-run welding method, and the welding method involves casting the weld metal into the groove, so the groove cross-sectional area and excess Once the sum of the cross-sectional areas is determined,
The welding speed is determined by the amount of wire fed into the groove per unit time, that is, the wire feeding speed. Therefore, in on-site welding where the groove width varies and the groove cross-sectional area and reinforcement cross-sectional area vary, adjusting the welding speed indirectly adjusts the wire feeding speed. . Here, the upper limit of T _A + T _B is 50 mm. If it exceeds that range, poor penetration will occur more frequently. Also, the lower limit is 28mm. If it is less than that, undercuts will occur and a large amount of rework will be required. Mata T _A
-The absolute value of T _B must be kept below 6 mm,
If it is more than that, the difference in plate thickness will be large and sound welding will not be possible. Furthermore, the above results were obtained using solid wires and flux-cored wires with a wire diameter of 1.2 mm to 2.0 mm, but for long welding, wire diameters of 1.5 to 1.7 mm are used.
mm solid wire was suitable. Flux-cored wires often produce spatter-like slag, and a large amount of spatter-like slag adheres to the chip 6 shown in FIG. 4 and cannot be removed during welding, making it unsuitable for long length welding. Also, solid wires with a wire diameter of less than 1.5mm are
The wire is soft and buckles many times during feeding.
Furthermore, since the straightness of the wire is poorer than that of a wire with a wire diameter of 1.5 to 1.7 mm, it is difficult to control the arc aiming position. In addition, solid wire with a wire diameter exceeding 1.7 mm has good wire straightness, but the wire is hard and the tip is subject to severe wear, so the hole diameter of the tip increases and
The arc aiming position is easy to go wrong. For the above reasons,
For long welding of 3 m or more, a solid wire with a wire diameter of 1.5 to 1.7 mm is suitable because it causes less spatter. Also, when performing horizontal electrogas welding, the fifth
By setting the wire protrusion length P in the figure to an appropriate range of 30 mm to 60 mm, it is easy to maintain the arc aiming position at an appropriate position. FIG. 2 shows the relationship between the wire feeding speed W (unit: m/min) and welding current I (unit: A) for a solid wire with a wire diameter of 1.5 to 1.7 mm to maintain the above state. The appropriate area A sandwiched between straight lines a and b is
The wire protrusion length is maintained at 30 mm to 60 mm. Welding current corresponding to these straight lines a and b
Ia, Ib (unit A) and wire feeding speed W (unit m/
The relationship with min) can be determined from the figure as shown in the following equation. Ia=20W+160 Ib=20W+200 Therefore, the appropriate welding current I has the relationship Ia≦I≦Ib. In inappropriate area B, the welding current I is excessive relative to the wire feeding speed W, and the wire protrusion length becomes short, which may damage the chip. The welding current I is too small relative to the feed speed W, and the protruding length of the wire becomes long, making it difficult to accurately direct the wire tip to the appropriate position in the molten pool, resulting in arc instability. tends to occur. Furthermore, the lower limit of the current value used for solid wires with a wire diameter of 1.5 to 1.7 mm is 330A. If it is less than this, the arc transition state is poor and spatter is likely to occur. Also, the upper limit is 450A. If it exceeds this range, spatter is likely to occur and the spatter will accumulate on the chip, making it unsuitable for long welding. Furthermore, a suitable relationship exists between welding current I (in A) and welding voltage E (in V) for transverse electrogas welding. The relationship is shown in FIG. Region A narrowed by curves a and b is the appropriate region. Welding voltage Ea corresponding to these curves a and b,
The relationship between Eb (unit: V) and welding current I (unit: A) can be determined from the figure as shown in the following equation. Ea=1.147I ^0.55 -1 Eb=1.147I ^0.55 +1 Therefore, the appropriate welding voltage E has the relationship Ea≦E≦Eb. The welding voltage E at this time indicates the voltage between the chip and the base metal. In region B, the welding voltage E is excessive relative to the welding current I, and therefore the arc spreads excessively, causing the molten metal to advance as shown in FIG.
Welding will be defective. Also, in inappropriate area C,
Welding voltage E is too small with respect to welding current I,
Therefore, the spread of the arc is too small, resulting in a welding result with poor penetration into the upper base metal side as shown in FIG. As the shielding gas, CO ₂ gas may be used because it is inexpensive, or a mixed gas of CO ₂ and O ₂ may be used because it increases the temperature of the hot water surface and improves melting. (Example) The conditions carried out here are shown below. Steel type: SM-41B Plate thickness: 14mm to 25mm Groove shape: I-type groove gap G: 8mm to 16mm Shielding gas flow rate: 30/min Polarity: DC reverse polarity Arc swing width: Lower base material plate thickness T _B -4mm Number of arc swings: 40 to 100 times/min Other conditions are listed in Table 1. As is clear from Table 1, if the welding conditions of experiments No. 1 to 12 according to the present invention were performed, there was no molten metal level advance or poor penetration on the upper base metal side, and the joint was suitable for long welding and was sound. were obtained, but Comparative Examples No. 13 to 16
Nos. 17 to 22 are wire type or wire diameter, Nos. 23 and 24 are wire feeding speed and welding current, and Nos. 25 and 26 are However, a satisfactory joint could not be obtained because the relationship between welding current and welding voltage deviated from the conditions of the present invention. Table 1 shows the judgment of welding results such as presence or absence of hot metal level advance, insufficient penetration of the upper base metal side, and suitability for long welding. The judgment was not made because the judgment was x. In other words, when determining the suitability for long welding, those with a horizontal line drawn are those where there is insufficient penetration on the upper base metal side or there is a molten metal level ahead, making it impossible to weld stably. If there is a horizontal line in the determination of insufficient penetration on the base metal side, there is a molten metal level ahead, welding cannot be performed stably, and it was not possible to determine whether there was insufficient penetration on the upper base metal side.

【table】

[Table] (Effects of the invention) As explained above, the welding method of the present invention in which welding conditions are appropriately set can provide stable and highly efficient horizontal welding, and its industrial value is extremely high. .

[Brief explanation of drawings]

Figure 1 is a diagram showing the relationship between plate thickness and welding speed of the present invention, Figure 2 is a wire diameter of 1.5 to 1.7 mm of the present invention.
Fig. 3 is a diagram showing the relationship between the welding current and welding voltage of the present invention, and Fig. 4 is a diagram showing the implementation status of the horizontal electrogas welding method. 5 is a front partial sectional view of FIG. 4, FIG. 6 is a perspective view showing a welding defect, and FIG. 7 is a sectional view perpendicular to the weld line showing a welding defect. 1: Upper base material, 2: Lower base material, 3: Fixed backing material,
4: Sliding copper butt, 5: Welding wire, 6: Chip,
7: Weld metal, 8: Molten metal, 9: Molten metal surface, 10:
Poor penetration, T _A : Thickness of upper base material, T _B : Thickness of lower base material, G: Groove gap amount, P: Wire protrusion length.

Claims (1)

[Claims] 1. The upper base material and the lower base material are I-shaped or V-shaped close to I-shaped.
Formed into a rectangular groove, fixed backing material on the back side of the groove,
Or, a sliding copper butt is brought into contact with the groove surface, and the sliding copper butt is brought into contact with the groove surface, the fixed backing material, the sliding copper butt, and the sliding copper butt. The welding wire is inserted through the flat tip into the space thus formed, and the tip of the welding wire is swung in the direction of the plate thickness, and the trolley travels under automatic control by detecting the welding current. In the horizontal electrogas welding method, in which the groove is welded in one pass and one run using a dolly, a solid wire with a diameter of 1.5 to 1.7 mm is used, and the plate thickness T _A (unit: mm) of the upper base material, In relation to the plate thickness T _B (unit: mm), welding speed V (unit: cm/min), lower limit value Va that satisfies the following formula,
During the upper limit value Vb, adjust the wire feeding speed so that Va≦V≦Vb, where Va=3201/T _A +T _B −1.5 Vb=3201/T _A +T _B +1.0, and Set the welding current I (unit A) to the lower limit value that satisfies the following formula for the feeding speed W (unit m/min).
Ia, upper limit Ib Ia≦I≦Ib Here, the welding current is set so that Ia=20W+160 Ib=20W+200, and the welding voltage E (unit V) is set for the welding current I (unit A). )
Set the welding voltage E between the lower limit Ea and upper limit Eb that satisfy the following formula: Ea≦E≦Eb, where Ea=1.147I ^0.55 −1 Eb=1.147I ^0.55 +1 A horizontal electrogas welding method characterized by: