JPH0577048A - Electric conductive nozzle for a large quantity of input heat - Google Patents

Abstract

PURPOSE:To provide an electric conductive nozzle having excellent electric conductive characteristic and wire feedability in a large quantity of input heat welding, particularly a plural electrode submerged arc welding of high current and a large quantity of the input heat. CONSTITUTION:In the electric conductive nozzle used at the time of executing the multi-electrode submerged arc welding having >=5.3mm wire diameter, >=1500 A used current and >=250KJ/cm input heat quantity for welding, in the case of using dw (mm) for the diameter of the wire 1, D1 (mm) for the inner diameter of the electric conductive nozzle 2 and D0 (mm) for outer diameter of the nozzle, the relations of D/dw=1.75-6.0, D1+10mm<=D0<=D1+50mm are satisfied and the nozzle is made of copper or copper alloy and also this nozzle has the structure cooling with water from the inner part or the outer part thereof.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a large-heat-input current-carrying nozzle, and more particularly to a current-carrying nozzle having excellent current-carrying characteristics and wire feedability in multi-electrode submerged arc welding with high current and large heat input. is there.

[0002]

2. Description of the Related Art In recent years,
With the soaring land prices and the increase of intelligent buildings with high-tech functions,
Buildings have become ultra-high-rise and large-spaced, and the steel columns used have a tendency to become thicker, and welding of super-thick plates of 40 to 100 mm is performed at various places.

In thick plate welding, submerged arc welding (SAW), which enables high current welding using a large-diameter wire and obtains a high deposition rate, is generally widely used.
The following problems occur with high current and high heat input welding.

The current supply to the wire becomes unstable, the wire feeding is not stable (knocking state), and as a result, defects such as poor penetration and slag entrainment are likely to occur.

Since the wire feeding is completely stopped, it takes a lot of time and labor to rework the starting portion and the crater portion of the welding bead.

Considering that the current energizing nozzle has an inner diameter of 7.5 mmφ and an outer diameter of 25 mmφ and is not water-cooled, it is considered that these problems are caused by the following reasons.

Since the current is not applied only to the current-carrying tip but also to the wire in the current-carrying nozzle, the wire protrusion length changes significantly, resulting in a variation in welding conditions, that is, unstable wire feeding. Occurs.

Due to the high current and the radiant heat of the high heat input welding, the temperature of the current-carrying tip and the current-carrying nozzle becomes abnormally high, and the frictional resistance with the wire becomes very large. ..

In the case of large heat input welding, one of the causes is that the wire feeding speed is fast, and one of the causes is that the linearity cannot be kept constant at the beginning and end of use of the wire.

The present invention solves the above-mentioned problems of the prior art and provides an energizing nozzle having excellent energization characteristics and wire feedability in large heat input welding, particularly in multi-electrode submerged arc welding with high current and large heat input. The purpose is to do.

In order to solve the above problems, the present inventor has studied improvement measures for the shape, size, structure, etc. of the large heat input energizing nozzle, and as a result, has completed the present invention.

That is, according to the present invention, the wire diameter is 5.3 mmφ.
Above, working current 1500A or more, welding heat input 250KJ
/ Cm or more, in the energizing nozzle used when performing multi-electrode submerged arc welding, if the wire diameter is dw (mm), the nozzle inner diameter is D ₁ (mm), and the nozzle outer diameter is D ₀ (mm), then D ₁ / dw = 1.75 to 6.0, D ₁ +10 mm ≦ D ₀ ≦ D ₁ +50 mm, and the nozzle is made of copper or copper alloy, and is water-cooled from the inside or the outside of the nozzle. The gist of the present invention is a large heat input energizing nozzle.

The present invention will be described in more detail below.

[Action]

As described above, the large heat input energizing nozzle of the present invention regulates the inner diameter to the outer diameter, the ratio of the length to the inner diameter, the material, etc., and the reasons for limiting them are as follows. is there. In FIG. 1, 1 is a welding wire, 2 is an energizing nozzle, 3 is an energizing tip, dw is a wire diameter, D ₁
Is the nozzle inner diameter, D ₀ is the nozzle outer diameter, and L is the nozzle total length.

(Nozzle inner diameter D ₁ ) Even if the wire is straightened to improve the linearity of the wire, if D ₁ / dw is less than 1.75, the wire contacts the energizing nozzle and the energizing position is not stable. Furthermore, since it is a thick wire (5.3 mmφ), the rigidity of the wire is high and the contact resistance is also high. On the other hand, D ₁
When / dw exceeds 6.0, the nozzle diameter becomes too large, which makes it difficult to properly arrange the wires due to the distance between electrodes, the inclination, etc., and defects such as pear-shaped cracks are likely to occur. Further, although the coil diameter of the wire changes depending on the start and end of the wire, if the nozzle diameter becomes too large, the linearity of the wire cannot be kept constant and the wire feeding speed becomes unstable. Further, if the nozzle diameter becomes too small, the nozzle comes into contact with the wire, and the wire feeding speed becomes unstable. Therefore, the nozzle inner diameter is D ₁ /dw=1.75 to 6.0.

When (nozzle outer diameter D ₀ ) D ₀ <D ₁ +10 mm, the rigidity of the energizing nozzle is poor, and the energization amount per nozzle cross-sectional area is excessive, and the heat generation of the nozzle and the resulting increase in the electrical resistance value result. Accurate welding conditions cannot be grasped, leading to the occurrence of defects. On the other hand, if D ₀ > D ₁ +50 mm, the nozzle diameter becomes too large, so it becomes difficult to properly arrange the wires due to the distance between electrodes, the inclination, etc., and defects such as pear-shaped cracks are likely to occur. Therefore, regarding the nozzle outer diameter, D
₁ + 10 mm ≦ D ₀ ≦ D ₁ +50 mm.

(Water Cooling of Nozzle) It is indispensable to cool the nozzle to prevent the energizing tip and the energizing nozzle from becoming hot and to reduce the frictional resistance with the wire. Structure It is desirable to water-cool the entire length of the nozzle, but a structure in which only the lower half is water-cooled is also possible. Nozzles Water-cooled nozzles are also used in other construction methods (eg, high-current CO ₂ welding), but with high-current, large-heat-input SAW using large-diameter wires, the effect is not sufficient just using water-cooled nozzles. Therefore, it is necessary to use it in combination with the above-mentioned specifications of the inner diameter and outer diameter of the nozzle. If water cooling of the energizing tip portion is also performed at the same time, a better effect can be obtained. However, the current-carrying tip part needs to be replaced frequently, so a water-cooled structure will be created with this in mind. A method of coating the inner surface of the current-carrying nozzle with resin, ceramic, or the like can be considered, but the result is almost the same as that of water cooling, and the cost is high.

(Nozzle material) In terms of frictional resistance, specific heat and electric resistance, it is preferable to use copper or copper alloy. In this case, considering the wear resistance of the inner surface of the nozzle, the inner surface or the inner surface of the nozzle may be plated with Ni, Cr or the like.

(Nozzle length L) The length L of the nozzle is appropriately determined, but in relation to the inner diameter of the nozzle, 0.005 ≦ D ₁ / L
It is preferable to regulate it in the range of ≤0.060. D ₁ / L <
At 0.005, the wire easily touches the energizing nozzle,
It becomes difficult to stabilize the energized position, the wire feeding becomes unstable, and when D ₁ /L>0.060, the nozzle diameter becomes too large, which makes it difficult to properly arrange the wire due to the distance between electrodes, the inclination, etc. This is not preferable because defects such as cracks are likely to occur.

The energizing nozzle of the present invention can achieve the desired effect only when it is used for large heat input welding under the following conditions.

That is, first, when high current, high heat input welding is performed, a single electrode is inferior in pear-shaped cracking resistance and bead appearance and is not preferable for welding. Must be welded. Even with multiple electrodes, the heat input is 250 KJ / cm or less and the current is 1500 A.
In the following, although the welding speed is inferior and inefficient, the wire feedability is not a problem, but the heat input amount is 250 KJ / cm or more, the current is 1500 A or more, and especially 3 electrodes (wire diameter 6.4
When the current is 2000 A or more (in the case of mmφ), the wire feedability tends to deteriorate.

On the other hand, the wire used has a wire diameter of 5.
If it is less than 3 mmφ, the defect resistance during large heat input welding (pear-shaped crack,
It is not preferable in terms of slag entrainment, etc.) and bead appearance, so it is necessary to use a wire diameter of 5.3 mmφ or more.

Other conditions of the energizing nozzle may be the same as those of the conventional one. A structure in which the energizing nozzle is connected with a screw or the like to adjust the length is also possible, but an integrated structure is preferable in consideration of an increase in electric resistance. If the lower end of the energizing nozzle, that is, the inner diameter of the nozzle near the energizing tip is provided with a taper, it is easy to guide the tip of the wire, but the taper may not be provided.

Next, examples of the present invention will be described.

[0025]

【Example】

[Table 1] An energizing nozzle under the conditions shown in was prepared. Using this energizing nozzle, JIS Z 3351 YS-S as a welding wire
6 Submerged arc welding test with two kinds of welding conditions (a) and (b) using the joint shown in Fig. 2 using the corresponding wire diameter of 6.4 mmφ and the flux corresponding to JIS Z 3352 FS-BT1 respectively. Was carried out, and the wire feedability and electrical conductivity, and the number of times the wire feed was stopped (the number of stops per 7.5 m) were investigated. The number of times the wire feeding was stopped was determined by welding three test pieces each having a length of 2.5 m and stopping the wire per 7.5 m. The results are also shown in Table 1.

Welding conditions a: (L) 2600A-40V-22cm / min, (M) 2100A-52V, (T) 1600A-50V. Welding conditions B: (L) 1450A-34V-65 cm / min, (M) 1250A-45V, (T) 950A-48V. Here, L is a first electrode (leading electrode), M is a second electrode, and T is a third electrode.

As is clear from Table 1, when the current-carrying nozzle of the present invention is used, the nozzle feeding property and the current-carrying property are excellent even in high heat input welding. On the other hand, the No. 5 and No. 9 energizing nozzles are the current ones, but the energizing nozzles of the comparative examples including these are poor in wire feedability and energization when used for large heat input welding. .. However, under the welding condition (B) where the heat input is small, there is no problem in the wire feedability, but the welding speed is inferior.

[0028]

As described in detail above, according to the present invention,
It is possible to provide a current-carrying nozzle having excellent current-carrying characteristics and wire feedability in large-heat-heat welding, particularly in multi-electrode submerged arc welding with high current and high heat-input, and it has a great effect on thick plate welding.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an energizing nozzle and a tip,
(A) is a side view, (b) is a cross-sectional view taken along the line AA of (a).

[Explanation of symbols]

 1 Welding wire 2 Energizing nozzle 3 Energizing tip

Claims (1)

[Claims] 1. A wire diameter of 5.3 mm or more and a working current of 15
In the energizing nozzle used when performing multi-electrode submerged arc welding with a heat input of 250 A or more and a heat input of 250 KJ / cm or more, the wire diameter is dw (mm), the nozzle inner diameter is D ₁ (mm), and the nozzle outer diameter is D ₀ (mm). ), D ₁ /dw=1.75 to 6.0, D ₁ +10 mm ≦ D ₀ ≦ D ₁ +50 mm, and the nozzle is made of copper or copper alloy, and An energizing nozzle for large heat input that has a structure that is water-cooled from the outside.