JP3818469B2 - Advanced welding method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a welding algorithm in the case of using a flux tab at a welding start position and an end position when performing upward welding of a groove of a large-sized welded structure composed of thick plates.
[0002]
[Prior art]
Conventionally, when welding a groove of a workpiece of a large steel welded structure composed of thick plates, if this workpiece cannot be rotated with a positioner etc. to perform downward welding or horizontal welding, upward welding (Vertical welding) is performed. In this upward welding, arc stability comparable to that in the flange groove is used to prevent molten metal flow at the lower end of the weld line, that is, the welding start end, and at the upper end, ie, the end of welding, and to stabilize the arc. It is common to use steel tabs with a lower end and an upper end. This steel tab has electrical conductivity, and as long as the steel tab is used, the tab portion, that is, the start and end portions and the inside of the groove can be welded under the same welding conditions. Welding quality can be ensured.
[0003]
[Problems to be solved by the invention]
Usually, since welding defects are likely to occur at the start and end portions of welding, there are cases where the welding quality such as the amount of penetration at the start and end portions is inspected with the steel tab still welded after welding. However, since there is a steel tab, it is difficult to inspect the welding quality by visual inspection. Therefore, it must be inspected by non-destructive inspection or the like, and the inspection of the welded portion of the tab portion takes a very long time. Has occurred.
[0004]
Further, excessive stress tends to concentrate on the welded portion between the steel tab and the base material, and the problem of cracks in the steel structure due to this has recently become prominent. For example, as shown in FIG. 10, excessive stress concentration occurs due to an earthquake or the like in the weld portion P between the base material 11 and the steel tab 12 welded to the end portion of the base material 11. It has recently been found that cracks occur from the weld P. One way to solve this problem is to remove the steel tab 12 after welding. In general, when the steel tab 12 is used, it is not necessary to remove the steel tab 12 when there is no particular structural or construction problem after welding. However, when there is a problem as described above, or during assembly, for example. When there is a problem such as interference with other structures, it is necessary to cut and remove the steel tab 12.
However, the removal work of the steel tab 12 has a problem that it is very complicated and requires a lot of time, such as cutting the steel tab portion or smooth-grinding the surface after the cutting. Therefore, recently, attention has begun to use a non-conductive flux tab instead of the steel tab 12. By using this flux tab, it becomes easy to remove the flux tab after welding, and the welding quality such as the amount of penetration after the removal can be easily inspected visually.
[0005]
However, when the conventional welding technique is applied to upward welding using a flux tab made of non-conductor such as ceramics, an arc is generated at the flux tab portions located at the lower end (start end portion) and the upper end (end end portion). It becomes very unstable and a hot water flow occurs. For this reason, the problem that sufficient welding quality is not securable in the start end part and a termination part has arisen. As a means for solving this problem, for example, Japanese Patent Application Laid-Open No. 57-68289 discloses a technique using a flux tab in which the contact surface between the flux tab and the base material is a solid iron powder layer. However, when welding is performed under conventional welding conditions at the start and end portions using the flux tab disclosed in this publication, impurities are generated from the flux tab during welding, and the arc becomes very unstable. As a result, there arises a problem that the welding quality is deteriorated and the strength is impaired.
[0006]
The present invention has been made paying attention to the above-mentioned problems, and an object of the present invention is to provide an advanced welding method capable of obtaining good welding quality at the lower end and upper end of a groove using a flux tab. It is said.
[0007]
[Means, actions and effects for solving the problems]
In order to achieve the above object, according to the first aspect of the present invention, the main body is formed of a non-conductive material on the lower end surface of the work groove and has a groove. The flux tab 5 having a surface formed of a conductor layer is brought into contact, and before the workpiece groove is welded upward, arc welding is started from the inside of the groove of the flux tab 5 at the lower end to perform upward welding. In the upward welding method, the welding of the flux tab 5 below the lower end of the workpiece groove is advanced with predetermined welding conditions, and the workpiece groove is changed to a welding condition suitable for the workpiece groove. And the method of welding .
[0008]
According to the invention described in claim 1, since the arc starts from the inside of the groove of the flux tab that is in contact with the end surface of the lower end of the work groove, the welding torch is pushed in at the start of welding due to a gap at the welding start position. Can be suppressed. In addition, since the surface of the groove of the flux tab is formed of a conductor layer, the arc at the groove of the flux tab is stabilized, so that it is possible to ensure the welding quality in the upward welding using the flux tab. It becomes. Also, in the upward welding, the welding conditions at the groove tab of the lower end and the welding conditions at the workpiece groove can be set to different conditions suitable for each, so the respective conditions at the flux tab and the workpiece groove. The welding quality can be sufficiently secured.
[0011]
In the invention according to claim 2 , the locus of the tip of the welding torch in the groove of the flux tab 5 at the lower end of the workpiece groove is on the inner side farther from the groove surface than the locus in the workpiece groove. The upward welding method according to claim 1 .
[0012]
According to the second aspect of the present invention, in the groove of the flux tab at the lower end, the locus of the tip of the welding torch (that is, the target position of the welding torch) is set inside the locus in the workpiece groove. This means that the welding torch aims inside the wall of the flux tab, and therefore the amount of impurities ejected from the flux tab during welding is reduced, so that the arc is stable and the welding quality at the flux tab is improved. Can be secured. As a result, upward welding using a flux tab is possible.
[0013]
According to a third aspect of the present invention, a main body portion having a groove formed on the upper end portion end surface of the workpiece groove is formed of a non-conductive material, and a surface of the groove is formed of a conductor layer. and the flux tab 6 is contacted, in the groove of the flux tabs 6 are the UeSusumu welding method of claim 1 wherein the UeSusumu welded at predetermined welding condition different from the welding conditions at the work GMA.
[0014]
According to the third aspect of the present invention, a flux tab having a conductor layer formed on the surface of the groove is brought into contact with the upper end portion of the work groove, and the groove of the upper end portion of the flux tab has a work opening. Advance welding is performed under conditions different from the previous welding conditions. Thereby, the arc at the flux tab at the upper end can be stabilized, and the upward welding can be performed under welding conditions suitable for the groove of the flux tab. As a result, when the flux tabs are attached to the lower end portion and the upper end portion of the workpiece groove and are welded upward, it is possible to ensure the welding quality.
[0015]
The invention according to claim 4 sets the welding conditions and the welding torch trajectory of each layer at the time of multilayer deposition for each groove of the workpiece groove and the flux tab 5 at the lower end of the workpiece groove, It is a UeSusumu welding method of claim 1 wherein performing UeSusumu welding multi-pass based on the welding conditions and welding torch trajectory.
[0016]
According to the invention described in claim 4 , in the upward welding at the groove of the workpiece groove and the flux tab at the lower end, the welding conditions and the groove in each layer during multi-layer welding at each groove The welding torch trajectory is adapted to each groove, and multilayer overlay welding is possible based on the welding conditions and the welding torch trajectory. Therefore, it is possible to ensure the quality of multi-layer welding by upward welding with a work groove using a flux tab.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments will be described with reference to the drawings.
FIG. 1 shows an example of a work to which upward welding according to the present invention is applied, and here, a description will be given by taking a welded portion of a steel column as an example. Normally, the welded portion of the steel column is welded in a welding line equipped with a welding robot, but the welding robot is not shown here. In the present invention, the method for moving the welding torch is not limited to the method using the welding robot. For example, another automatic device or manual operation may be used. Therefore, a specific welding torch moving device is not described below.
[0018]
The column 1 of the steel column is composed of a hollow member whose outer shape is a rectangular column shape, and a flange 2 formed of H steel is welded to the outer peripheral side surface of the column 1 in the longitudinal direction of the column 1. The flange 2 is welded so that the parallel members 2a and 2b of the H steel facing each other are orthogonal to the longitudinal direction of the column 1. The flange 2 is welded to the outer peripheral surface of the column 1 via a pair of diaphragms 3 and 3 welded in an annular shape. A groove (usually a labyrinth groove) is provided in the joint weld 4 between each diaphragm 3, 3 and each member 2a, 2b of the flange 2, and this steel column cannot be rotated by a positioner or the like. In some cases, the groove is welded by upward welding.
[0019]
FIG. 2 is a detailed perspective view of a work groove for performing the upward welding, and here, represents the groove of the joint welding portion 4. In the following description, the groove of the joint weld 4 is referred to as a work groove. In the same figure, since the groove shapes and welding conditions at the grooves of the members 2a and 2b of the flange 2 are the same, only the upward welding of the member 2a will be described for the sake of simplicity.
A groove is provided at the end of the member 2a facing the outer peripheral surface of the diaphragm 3, and the workpiece is installed such that the weld line direction of the groove is substantially in the vertical direction. Flux tabs 5 and 6 are in contact with the weld start end portion (the lower end portion of the weld line) and the weld end portion (the upper end portion of the weld line) along the weld line extension, respectively. Each of the flux tabs 5 and 6 has a groove having a predetermined length L1 and L2 in the extending direction of the weld line, and the groove angle (so-called groove angle) is determined by the workpiece groove (here, Is substantially the same as the groove of the flange 2.
[0020]
The main bodies of the flux tabs 5 and 6 are made of, for example, a non-conductive material such as ceramics, and a conductor layer having a predetermined thickness is formed on the surface of the groove portions of the flux tabs 5 and 6. This conductor layer can be formed of, for example, a metal powder such as iron powder or aluminum powder coated with a predetermined conductivity and having a predetermined thickness, or an aluminum foil or a zinc plate.
[0021]
FIG. 3 shows an example of a flowchart representing an upward welding sequence when using the flux tab according to the present invention. In addition, each step number of a flowchart attaches and represents S.
In S1, the welding torch is moved to the welding start position of the lower end portion of the groove where the upward welding is performed, and then in S2, the arc start is performed under the welding condition of the lower end tab portion (that is, the groove of the flux tab 5). . Then, in S3, it is determined whether or not the amount of movement of the welding torch in the welding line direction (here, the vertical direction) has reached the length L1 of the lower end tab, and if not, S3 is repeated to obtain the length L1. Until it reaches, the welding condition of the workpiece groove is immediately changed in S4, and then welding of the workpiece groove is continued. Next, in S5, it is determined whether or not the amount of movement of the welding torch in the weld line direction has reached the weld groove length L0 (see FIG. 2). If not, S5 is repeated. In step S6, the welding condition is immediately changed to the upper tab portion (that is, the groove of the flux tab 6), and then welding at the upper tab portion is continued. Then, in S7, it is determined whether or not the amount of movement of the welding torch in the weld line direction has reached the length L2 of the upper end tab portion. If not, the process repeats S7 and waits until the length L2 is reached. If so, the arc is stopped in S8 and the welding is terminated.
[0022]
Thus, for each groove portion, that is, the lower end tab portion, the work groove and the upper end tab portion, appropriate welding conditions are set for each groove, and the lower end tab portion using the flux tabs 5 and 6 is used. In addition, the welding conditions at the upper tab portion are different from the welding conditions of the workpiece groove. The welding conditions referred to here are welding current, welding voltage, welding speed (equal to welding torch tip speed), the trajectory drawn by the welding torch tip in the groove, and the stop timer at each stop position on this trajectory. It represents time etc. In addition, strictly speaking, the tip of the welding torch means a tip of the welding wire protruding from the welding torch by a predetermined protruding length.
[0023]
FIG. 4 schematically shows the welding torch tip trajectory of the lower end tab portion (starting end portion) of upward welding when using the flux tab. In the figure, the dotted line represents the locus in the flux tab 5, and the solid line represents the locus in the workpiece groove.
Here, the trajectory of two-layer multi-layer welding is shown, and the welding torch is the first layer, and each point in the flux tab 5 is P1 ′ → P2 ′ → P3 ′ → P4 ′ → P5 ′ → P1. After one-cycle weaving pattern of 'is repeated for a predetermined cycle and the welding is repeated, each point in the workpiece groove is repeatedly welded by repeating the weaving pattern of P1, P2, P3, P4, P5 and P1. Similarly, in the second layer, each point in the flux tab 5 is repeatedly welded in a predetermined cycle with a weaving pattern of one cycle of Q1 ′ → Q2 ′ → Q3 ′ → Q4 ′ → Q1 ′. Each point in the work groove is repeatedly welded in the weaving pattern of Q1, Q2, Q3, Q4, and Q1. As described above, the trajectory in the flux tab 5 is set to the inner side farther from the groove surface than the trajectory in the workpiece groove in each layer. This is because the non-conductive flux tab 5 melts and an arc breakage abnormality occurs, thereby causing the welding robot and the like to stop abnormally, so that the unmanned welding line is not hindered. This is to further reduce the weaving width. Further, a start arc is performed from a point P1 ′ inside the groove in the flux tab 5, thereby preventing the welding torch from being pushed into the gap at the end of the groove.
[0024]
In the lower tab portion, the welding current and the welding voltage are set according to the thickness of the conductor layer used in the flux tab 5, and are lower than the welding conditions at the work groove. Furthermore, in order to suppress the amount of penetration into the flux tab 5 to a predetermined value or less, it is controlled by the number or frequency of repeated cycles of the weaving pattern in the flux tab 5 or the upward speed in the welding line direction.
As a result, the amount of impurities generated from the flux tabs 5 and 6 can be suppressed, and the occurrence of an arc break abnormality can be prevented. Moreover, since the arc in the flux tabs 5 and 6 is stabilized by the conductor layer, the welding quality of the flux tabs 5 and 6 is improved.
[0025]
FIG. 5 schematically shows the trajectory of the welding torch tip of the upper end tab portion (end portion) of the upward welding when using the flux tab, and the dotted line represents the trajectory in the flux tab 6 as described above, and is a solid line. Represents the trajectory in the workpiece groove.
Here, the trajectory in the case of a two-layer multilayer is also shown, and the welding torch is the first layer, and each point in the workpiece groove is a weaving pattern of P1, P2, P3, P4, P5, P1. After repeating the upward welding, the points in the flux tab 6 are repeatedly advanced for a predetermined cycle with a weaving pattern of P1 "→ P2 '' → P3 '' → P4 '' → P5 '' → P1 ''. Weld, and finish welding at point P1 ''. In the second layer, similarly, each point in the workpiece groove is repeatedly welded in a weaving pattern of Q1, Q2, Q3, Q4, and Q1, and then each point in the flux tab 6 is Q1 '. '→ Q2''→Q3''→Q4''→Q1''Welding is repeated a predetermined cycle with the weaving pattern, and the welding is terminated at point Q1''. As described above, the trajectory in the flux tab 6 is set on the inner side of the groove with respect to the trajectory in the work groove for each layer similarly to the lower end tab portion, and the weaving width of the weaving pattern is reduced. This is because, when welding at the upper end tab portion, since the heat when the workpiece groove has been welded upward is transmitted to the flux tab 6, the flux tab 6 is very easy to melt. It is. Therefore, the welding current, welding voltage, and welding speed at the upper end tab portion are also changed from the conditions at the workpiece groove.
[0026]
FIGS. 6-8 has shown an example of the welding conditions of a workpiece | work groove | channel, a lower end tab part, and an upper end tab part, respectively, and has shown only the conditions of the 1st layer. Here, the point represents the position on the locus of the tip of the welding torch within the groove of each part as shown in FIGS. 5 and 6, and the welding torch moves between each point by linear interpolation in the case of a robot, for example. It shall be. X, Y, and Z represent the relative position of each point from the reference point (P1 for the workpiece groove, P1 ′ for the lower tab portion, and P1 ″ for the upper tab portion). The current, voltage and speed represent the welding current, welding voltage and welding speed when moving to the point, and the stop timer represents the time for maintaining the welding current and welding voltage after reaching the point. In this way, the workpiece groove is welded upward under the welding conditions suitable for the groove, and the flux tabs 5 and 6 at the lower end and the upper end are respectively smaller than the welding conditions at the workpiece groove. ing. For example, each point is about 1 to 3 mm inward so that the locus is inside the groove in plan view from the locus at the flange groove, and the welding current and welding voltage are 5 to 15 A and 0 to 3 V from the flange groove, respectively. It is small and the stop timer is small. When the current is not reduced, the position of each point in the height direction (Z direction in the figure) may be increased or the speed may be increased.
[0027]
FIG. 9 is a flowchart showing another sequence example of upward welding when using a flux tab. Note that steps having the same processing contents as those in the flowchart shown in FIG. 3 are given the same step numbers, and the following description will focus on steps for performing different processing.
First, in S2, arc start is performed under the welding conditions of the lower end tab portion in the same manner as described above, and upward welding is performed toward the workpiece groove. Next, in S13, it is determined whether or not the position of the welding torch in the weld line direction (here, the vertical direction) is within one cycle before the workpiece groove. Here, it is determined whether or not it is within one cycle before the workpiece groove. The distance in the welding line direction from the current position to the workpiece groove position is larger than the upward distance during one cycle upward welding at the lower end tab portion. Judgment is based on whether it is small or not. If it is not within one cycle, repeat S13 and wait until it is within one cycle. If it is before, the process proceeds to S4 as described above and immediately changes to the welding condition of the workpiece groove. Continue upward welding of workpiece groove.
[0028]
In this way, in this example of the upward welding sequence, when it is within one cycle before the workpiece groove position, the welding condition is changed to the welding condition of the workpiece groove and the upward welding is performed. Accordingly, the position where the welding condition of the workpiece groove is switched can be prevented from entering the workpiece groove, so that the welding strength of the workpiece groove can be surely enhanced.
[Brief description of the drawings]
FIG. 1 shows an example of a workpiece to which upward welding according to the present invention is applied.
FIG. 2 is a detailed perspective view of a workpiece groove for performing upward welding.
FIG. 3 shows an example of a flowchart of an upward welding sequence when using a flux tab.
FIG. 4 represents a welding torch tip locus of a lower end tab portion of a flux tab for upward welding.
FIG. 5 shows a welding torch tip locus of an upper end tab portion of an upward welding flux tab.
FIG. 6 shows welding conditions of a workpiece groove for upward welding when using a flux tab.
FIG. 7 shows welding conditions for the lower end tab portion of upward welding when using a flux tab.
FIG. 8 shows the welding conditions of the upper end tab portion of upward welding when using a flux tab.
FIG. 9 is a flowchart illustrating another sequence of upward welding when using a flux tab.
FIG. 10 is an explanatory diagram of a welded portion of an open tip portion using a steel tab according to the prior art.
[Explanation of symbols]
1 ... pillar, 2 flange, 3 diaphragm, 4 joint weld, 5, 6 flux tab, 11 base material, 12 steel tab.

Claims (4)

A flux tab (5) having a main body formed of a non-conductive material and having a groove and a surface of the groove formed of a conductor layer is brought into contact with the end surface of the lower end of the workpiece groove. In the upward welding method in which arc welding is started from the inside of the groove of the flux tab (5) at the lower end before performing upward welding on the workpiece groove ,
Welding is performed under predetermined welding conditions at the groove of the flux tab (5) below the lower end of the work groove, and the work groove is changed to a welding condition suitable for the work groove and welded. An upward welding method characterized by the above. The locus of the tip of the welding torch in the groove of the flux tab (5) at the lower end of the workpiece groove is on the inner side farther from the groove surface than the locus in the workpiece groove. Item 6. An upward welding method according to item 1 . The upper end of the workpiece groove is in contact with a flux tab (6) having a main body formed of a non-conductive material and having a groove and the surface of the groove formed of a conductor layer. is allowed, UeSusumu welding method according to claim 1, characterized in that UeSusumu welded at predetermined welding condition different from the welding conditions at the work GMA in the groove of the flux tab (6). For each groove of the workpiece groove and the flux tab (5) at the lower end of the workpiece groove, the welding condition and welding torch locus of each layer during multi-layer deposition are set, respectively. UeSusumu welding method according to claim 1, wherein the performing UeSusumu welding multi-pass based.

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