KR101621696B1 - Filler metal shape for TIG welding - Google Patents

Abstract

An object of the present invention is to provide a filler material for welding a tig weld which has a larger heat flux input area and increased heat input per unit length than a general wire filler material, thereby achieving stable welding.
The filler for tig welding according to an embodiment of the present invention is characterized in that an electrode is positioned at the upper end of the base material, an arc is formed between the electrode and the base material, a shield gas is supplied around the arc, In the case of the filler for tig welding which is melted by the arc, the cross section of the filler has a shape in which the surface in the direction of the electrode is concavely curved in the direction of the electrode.

Description

[0001] The present invention relates to a filler metal for TIG welding,

The present invention relates to a filler for TIG welding, and more particularly to a filler for TIG welding having high welding productivity.

In general, carbon steel, which is a low-grade material, is mainly used in piping systems for power generation facilities, offshore plants or petrochemical plants. It is a heterogeneous metal with high heat resistance, durability and corrosion resistance such as stainless steel or nickel alloy on its inner surface. It is used by welding. This method is a method of improving the corrosion resistance, durability, abrasion resistance and strength by coating the metal surface when the metal having weak physical properties is used in a very weak environment, It is widely used because it can match characteristics.

Many kinds of automation devices have been developed and used for the above-mentioned upwelling welding. For example, Patent No. 909596 relates to an automatic pipe-growing welding apparatus for a pipe, comprising: a rotating chuck for inserting and fixing a pipe and rotating the pipe; A pair of guide wires arranged horizontally and parallel to each other through a pipe fixed to the rotary chuck; A pulling portion for pulling the guide wire; A welded portion supported by the guide wire and movable along the inside of the pipe, for performing upset welding on the inner surface of the pipe; And a controller for controlling the rotation of the pipe by the rotary chuck to move the welding part to one side so that the welding bead is continuously formed while forming the spiral of the welding bead on the inner surface of the pipe.

Japanese Patent No. 383014 relates to a hot wire tig welding torch, and is directed to a hot wire tig welding torch capable of smoothly performing the upside welding of the inner diameter of a pipe having a small diameter and a long length, A body portion connected to the connection portion and having an appropriate length and connected to both ends by an insulator and an electrode portion connected to the body portion in a longitudinal direction of the body portion so that a product having a pipe inner diameter of at least 150 mm can be welded , And 1.5M can be welded to the inside of the pipe, so that the present invention can be effectively applied to internal pipe-growing welding with a small diameter and a long length.

The above-described upsized welding apparatus proposes the welding method by TIG welding.

The TIG welding has an advantage that the welded portion has excellent mechanical properties, excellent corrosion resistance, and clean work environment, but has a problem of low productivity. In order to increase the productivity, it is necessary to increase the current and increase the welding speed. However, when the high current is used, the strong arc force due to the arc pressure causes a severe indentation phenomenon on the surface of the melting paper, and welding defects such as undercut, humpping bead, .

In order to increase the welding speed and increase the productivity, it is necessary to increase the speed of the wire transfer. However, when a thin wire of 1.0 or 1.2 mm is used, there is not enough time to absorb the arc heat due to high wire transfer speed. Even if the wire is misaligned, the wire can not be melted and escapes out of the molten pool to form an annealed wire. If such untreated wire is formed, the welding is stopped and the productivity is lowered, so that welding is performed at a sufficiently high current in the field. Therefore, in case of increasing the welding speed, it is necessary to increase the current basically. In this case, too, there is a disadvantage that it is difficult to apply because the welding is defective such as undercut due to large arc force and the penetration of the base material becomes large.

In order to overcome such disadvantages, Patent Application No. 2012-0096720 filed by the present applicant has been cited.

This patent proposes application of a filler having a flat plate-shaped cross-section to the tig welding, which is advantageous in that it exhibits a higher welding speed than the conventional wire type.

However, in the above patent, since it is confined to a rectangular flat plate section, there is room for improvement in a new type of combustible material section which shows a higher production speed by changing some cross-sectional shapes.

An object of the present invention is to provide a filler material for TIG welding which has a larger heat flux input area and an increased heat input per unit length than a general wire filler material, thereby enabling stable welding.

The filler for tig welding according to an embodiment of the present invention is characterized in that an electrode is positioned at the upper end of the base material and energy is continuously supplied from the electrode to the upper end of the base material to form an arc between the electrode and the base material, A center portion including a center line extending in the thickness direction from a center point of the cross section, the flat plate being a portion of which the cross section is expressed by a width and a thickness; And an end portion positioned at both ends of the cross section, and the end portion may have a concave shape bent toward the electrode.
The cross section may be symmetrical with respect to a vertical line from the base material.
The thickness of the central portion of the flat plate in the cross section may be thicker than the thickness of the end portion of the flat plate.
The thickness of the center portion of the flat plate at the cross section may be 1.1 to 2 times the thickness of the end portion of the flat plate.
The width may be 3 mm to 10 mm in the cross section, and the thickness may be 0.3 to 1 mm.
The material of the above-mentioned excipient may be selected from the group consisting of sus300 series, alloys 625, duplex sts2209 and super duplex.

delete

delete

delete

delete

delete

delete

delete

delete

delete

delete

delete

delete

delete

Since the filler for tig welding according to the present invention has a relatively large sectional shape curved concavely in the direction of the electrode unlike the conventional circular filler, the heat input amount absorbed widely by absorbing the heat flux transmitted through the electrode, It is effective to provide high productivity and stable welding even at a welding current and a low filler flux rate.

1 is a general configuration of a tig welding apparatus,
Fig. 2 is an arc shape graph generated in Fig. 1,
FIG. 3 is a plot-only stream curve graph based on the arc shown in FIG. 2,
Fig. 4 is a partial configuration of the stream curve shown in Fig. 3,
FIG. 5 is a normal drawn at a constant length in the stream shown in FIG. 3,
FIG. 6 is a cross-sectional curve connecting normal lines in FIG. 5,
Fig. 7 is a finished sectional curve of Fig. 5,
Figure 8 is another embodiment of Figure 6,
Figure 9 is another embodiment of Figure 6,
Figure 10 is another embodiment of Figure 6,
11 is the length of the cross section of the filler applied to the embodiment,
12 is a photograph of a bead of a comparative example,
13 is a photograph of a bead of the embodiment,
14 is another bead photograph of the embodiment,
15 is an explanatory diagram for cross-sectional analysis,
16 is a cross-sectional photograph of a bead of a comparative example,
17 is a cross-sectional photograph of the bead of the embodiment,
18 is another bead cross-sectional photograph of the embodiment,
19 is another bead cross-sectional photograph of the embodiment,
20 is a bead shape according to Test Example 4,
FIG. 21 is a cross-sectional view of the bead formed in FIG. 20, and bead height and penetration depth data according to the cross section.

Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings.

The shape of the cross-sectional shape of the filler material 10 for welding a tig according to the present invention is characterized in that the shape of the cross-sectional shape of the tig arc plasma is such that the amount of heat applied to the filler material 10 is the largest.

First, as shown in Fig. 1, the tig welding is carried out by using an electrode 1, a base material 2, an arc 3 formed between the electrode 1 and the base material 2, Is modeled as a shield gas (4).

The arc 3 starts at a point on the electrode 1 and is formed to have a constant width in the base material 2. Since the interior also transmits energy, the representation of the inside of the arc 3 is also important.

The interior of the arc 3 can be represented by a plasma stream 5, which is a function of position. Where the outline of the plasma stream 5 corresponds to the arc 3 shape.

The plane of the arc (3) is defined as a circle. That is, the arc (3) in FIG. 1 is defined as an axisymmetric shape.

On the other hand, in the arc 3 as described above, when the filler 10 is positioned in the normal direction to the plasma stream 5, the plasma generated by the arc 3 defines the highest amount of heat applied to the filler 10, The present invention is characterized in that the shape of the cross section of the filler (10) is determined by calculating the normal surface of the plasma stream (5).

Next, it is assumed that the shape of the arc (3) has a Gaussian distribution in a pressure distribution or a heat flux distribution formed on the plane of the base material (2) by the plasma only stream (5) therein, And the arc 3 on the welding of the tig 30 is formed on the assumption that the arc is distributed to the base material 2 starting from the electrode 1 and the distribution characteristic etc. diffused into the base material 2 .

Therefore, the shape f (r) of the arc 3 is defined as follows.

수학식 [1]

Equation [1]

Here, r denotes a radial distance with the electrode 1 as the origin, f (0) denotes the vertical distance between the electrode 1 and the base material 2, that is, the length of the arc 3, , Which is selected according to the radial distance of the arc (3).

2 is a graph showing the shape of the arc (3) when? = 1 and f (0) = 5.

On the other hand, the plasma stream 5 can select the r value based on the point at which the plasma stream 5 is connected to the parent material 2 by adjusting the value of f (0) after selecting the value of f (0) It has a disadvantage in that the r value can not be selected because it converges without being properly connected to the base material 2 in terms of characteristics.

Therefore, in the present invention, the plasma stream 5 is formed by adding +10% of the actual arc length 3, and r is selected based on the point where the actual arc length 3 meets the length.

The length of the arc (3) can be appropriately selected within ± 10%.

Figure 3 compares the arc (3) length 5 to the plasma stream 5 at 5.5 and the value at which the plasma stream 5 intersects at point 0 is r, where the r value increases by 0.5 units after the initial 0.25 Lt; RTI ID = 0.0 > 5 < / RTI >

And FIG. 4 is a view showing the plasma stream 5 from which the bottom 0.5 of the arc 3 length is removed.

On the other hand, a normal is calculated at a point where the y-value is zero (or a constant value) at the intersection of the x-axis and the plasma stream 5 close to the origin among the paths of the respective plasma streams 5, The normal connection curve of the plasma stream 5 can be obtained when the intersection of the plasma stream 5 is obtained and the tangent of each plasma stream 5 is obtained while the normal of the plasma stream 5 is obtained again at the intersection point have.

Fig. 5 is a diagram showing the normal line of the plasma stream 5, which is limited to a total of 10, and intersections are obtained by using the respective normal lines at five points.

When the normal points of each plasma stream 5 in FIG. 5 are continuously connected, a curve 6 shown in FIG. 6 can be obtained.

The curve 6 shows the highest energy absorption rate based on the fact that the plasma exhibits the highest energy absorption rate when the plasma impinges on the sparking material at 90 degrees. In addition, since the curve 6 is symmetrical, the cross-sectional curve 7 as shown in Fig. 7 actually shows the highest amount of heat input to the arc 3.

That is, all the arcs 3 momentarily generated through the electrode 1 are absorbed perpendicularly to the cross-sectional curve 7 in the same manner, and thus theoretically shows the highest amount of heat input.

The cross-sectional curve 7 shows the highest amount of heat of the filler 10 having the same shape. However, since the curves are expressed by complicated formulas and are difficult to produce in practice, Can be configured.

First, as shown in Fig. 8, the cross section of the filler material 10 is formed on the basis of a rectangular flat plate, and the lower end of the cross section is located at the origin of the arc 3 and the inclination of the center of the lower end of the cross section is 0, And can be defined as a cubic spline curve.

Here, the width of the rectangular flat plate is 3 mm to 10 mm, and the thickness is preferably 0.3 to 1 mm.

If the width of the flat plate is less than 3 mm, there is a problem in productivity. If it exceeds 10 mm, there is a problem in melting, and if the filler 10 does not exactly coincide with the electrode 1, have.

When the thickness of the flat plate is less than 0.3 mm, there is also a problem in productivity. When the thickness exceeds 1 mm, there is a problem in melting.

Further, the above-mentioned filler 10 may be made of any material used for ordinary tig welding. For example, stainless steel, sus300 series, alloy 625, duplex sts2209, shoe duplex and the like can be applied.

In the case of defining a cubic spline curve as described above, there is an advantage that the characteristic of the sectional curve 7 can be sufficiently reflected.

Further, as shown in Fig. 9, it is possible to constitute a cross section of the spark plug 10 constituted in an arc shape.

The cross section is very similar to the cross-section curve 7, and can be formed by bending partly on the flat plate, thereby exhibiting a higher heat input quantity than the circular or flat plate-like filler 10.

It is also possible to construct a secondary parabola whose center is located at the origin.

As shown in Fig. 10 (a), it can also be formed in the form of a bent plate. The cross section has a part different from the cross-sectional curve 7, but shows a high heat input at the end of the filler 10, so that an appropriate amount of heat input can be expected.

In addition, as shown in FIG. 10 (b), the center plate may be in the form of a flat plate, and a slant plate may be formed at both ends of the flat plate.

This structure is advantageous in terms of the supply of the filler 10 and the position under the electrode 1, although it is somewhat disadvantageous in terms of heat input.

10 (b), the center plate and the inclined flat plate can be formed with different thicknesses. In this case, since the heat input amount of the central flat plate portion is high, it is preferable that the thickness is formed thicker than the inclined flat plate, The thickness of the central flat plate is preferably 1.1 to 2 times the thickness of the inclined flat plate.

If it is less than 1.1 times, there is no effect. If it is more than 2 times, there is a possibility that the central plate portion is unfused.

Further, as shown in Fig. 10 (c), the central flat plate can be formed by forming the bent portion 9 thereon. The bent portion 9 may be utilized for feeding and guiding the spark plug 10.

That is, when the cross-sectional shape of the filler material 10 is formed concave toward the electrode 1 on the basis of the flat plate, the amount of heat input is higher than the filler 10 of the conventional circular cross-sectional shape, .

In addition, the cross section of the filler 10 may be formed concavely on the basis of the electrode 1 without being based on the plane, in which case it may be asymmetric.

Hereinafter, the present invention will be described in detail with reference to examples.

Example

A flat sheet member 10 of a sus304 material having a width of 5 mm and a thickness of 0.6 mm was bent and formed into a symmetric cubic curve having a width of 4.6 mm and a height of 1.7 mm as shown in Fig.

The base material was SS400, the welding speed was 38 cpm (cm / min), the current was 360 A, and the arc length was 7 mm.

The feed rate of the fugitive material 10 was increased from 250 cpm to 10 cpm to 400 cpm and the deposition rate per unit time was determined according to the feed rate. In the case of 250 cpm, 3.51 kg / hr and 400 cpm 5.62 kg / hr, and the intermediate feed rate is calculated by interpolation.

Comparative Example

TIG welding was performed under the same conditions as those of the embodiment in the case of the flat plate fusing material 10 of sus304 having a width of 5 mm and a thickness of 0.6 mm.

At this time, the feeding speed of the fugitive material (10) was increased from 250 cpm to 10 cpm and changed to 300 cpm only.

Test Example 1 (Bead appearance analysis)

The outer shapes of the beads were analyzed for the examples and comparative examples. 12 is an external view of a bead with respect to each feed rate in the comparative example, and it can be confirmed that an unmelted phenomenon appears when the feeding speed is 290 cpm or more.

13 and 14, it can be seen that a good bead having no cosolmation phenomenon is formed up to 400 cpm in the bead outer shape photograph according to each feed speed in the embodiment.

Test Example 2 (bead cross section analysis)

The sections of the beads formed by the above Examples and Comparative Examples were analyzed. As shown in Fig. 15, the bead cross section connects a line between two points a-b on the surface of the base material 2, and the penetration is measured from the center (point ①). (2), (3), (4) and (5)). After calculating the average of the five penetration depths, the maximum penetration depth is measured (points ⑥ and ⑦).

FIG. 16 shows the shape of the bead cross section according to the comparative example and the penetration depth data of the bead cross section, and FIGS. 17, 18 and 19 show the shape of the bead cross section according to the embodiment and the penetration depth data of the bead cross section. From the above data, it can be seen that the examples show the welding quality close to the comparative example.

Test Example 3 (maximum deposition rate)

When the maximum deposition rate was calculated through Test Example 1 and Test Example 2, the deposition rate of the embodiment was 5.6 kg / hr and the comparative example showed a deposition rate of 3.9 kg / hr. Thus, the filler 10 according to the embodiment was superior Indicating one productivity and also showing a similar weld quality as was found in Test Example 2. < tb >< TABLE >

Test Example 4 (Multiple Bead Formation Test)

Six bead layers were formed using the cross-section of the filler 10 of the example, and the cross-sectional characteristics were analyzed.

In this case, the welding conditions, a material of SS400, a welding speed of 38cpm (cm / min), current 360A, was the arc length is set to 7mm, the material of the filler metal 10 is STS304, feeding rate 360cpm, welding area 20mm ^2, welding Speed 5.02 kg / hr, torch weaving cycle 3 Hz, and weaving length 5 mm.

Fig. 20 shows the shape of the welded bead. Fig. 21 shows photographs of the cross section of the weld bead and data on the bead height and penetration depth at 15 positions on the cross section.

21 and 22, it was confirmed that uniform beads were produced.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, And all of the various forms of embodiments that can be practiced without departing from the technical spirit.

1: Electrode 2: Base material
3: arc 4: shield gas
5: Plasma stream 6: Curve
9: bent portion 10:

Claims (14)

Energy is continuously supplied from the electrode to the upper end of the base material so that an arc is formed between the electrode and the base material and is melted by the arc,
A center portion including a center line extending in the thickness direction from a center point of the cross section, the flat plate having a cross section expressed by a width and a thickness; And end portions positioned at both ends of the cross section,
The end portion having a concave shape bent toward the electrode,
Wherein a thickness of a central portion of the flat plate in the cross section is thicker than a thickness of an end portion of the flat plate.
The method according to claim 1,
Wherein the cross section is symmetrical with respect to a vertical line from the base material.
delete The method according to claim 1,
Wherein the thickness of the central portion of the flat plate in the cross section is 1.1 to 2 times the thickness of the end portion of the flat plate.
The method according to claim 1,
The width is 3 mm to 10 mm in the cross section, and the thickness is 0.3 to 1 mm.
The method according to any one of claims 1, 2, 4, and 5,
Wherein the material of the above-mentioned excipient is any one selected from the group consisting of sus300 series, alloys 625, duplex sts2209 and super duplex.
delete delete delete delete delete delete delete delete

Images