JP2017042779A - Welding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a welding method in which penetration welding is achieved in butt-welding by GMA welding so that a work efficiency in the welding can be improved.SOLUTION: The welding method comprises: a step for preparing a first base material 50 and a second base material 60; a step for arranging the first base material 50 and the second base material 60; and a step for welding the first base material 50 to the second base material 60 by GMA welding. In the step for welding the first base material 50 to the second base material 60, a molten area 12 is formed by heat of an arc 11. Further in the step for welding the first base material 50 to the second base material 60, an arc 11 is formed, while a position of a tip 15A is reciprocated between a first depth and a second depth, in a state where a welding wire 15 enters an area surrounded by the molten area 12, so that the molten area 12 is formed so as to penetrate in a thickness direction through the first base material 50 and the second base material 60.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a welding method.

  In butt welding, where the end faces of the pair of base materials are arranged so that the end faces are opposed to each other, the fusion region formed by welding is formed so as to penetrate the base material in the thickness direction. By doing this (through welding), the work efficiency of welding can be improved. Submerged arc welding is effective for achieving through welding. In butt welding employing submerged arc welding, measures have been proposed to achieve improvement in the quality of the welded portion (see, for example, Patent Documents 1 and 2).

JP 2010-212298 A JP 2007-260692 A

  However, in submerged arc welding, it is necessary to supply granular flux to the weld. Therefore, in the submerged arc welding, the welding posture is limited. Moreover, in submerged arc welding, the welding apparatus tends to increase in size.

  Submerged arc welding is easy to achieve through welding, but has the disadvantages described above. Therefore, an object of the present invention is to provide a welding method capable of improving the work efficiency of welding by achieving through welding in butt welding by GMA (Gas Metal Arc) welding.

  In the welding method according to the present invention, the first base material and the second base material are prepared, and the first end surface of the first base material and the second end surface of the second base material face each other. A step of arranging the base material and the second base material, and a step of welding the first base material and the second base material by GMA welding so that the first end face and the second end face are joined. In the step of welding the first base material and the second base material, an arc is formed between the welding wire, the first base material, and the second base material, and the first base material and the second base material are generated by the heat of the arc. The first base material and the second base material are welded by forming a melting region in the first part. In the step of welding the first base material and the second base material, the position of the tip of the welding wire is the thickness of the first base material and the second base material in a state where the welding wire has penetrated to the region surrounded by the melting region. The arc is formed while reciprocating between the first depth and the second depth deeper than the first depth in the direction, so that the melting region penetrates the first base material and the second base material in the thickness direction. To be formed.

  The inventors of the present invention have studied a method for achieving through welding by GMA welding. As a result, the following knowledge was obtained and the present invention was conceived. By performing welding while maintaining a state in which an arc is formed in a state where the welding wire has entered the region surrounded by the melting region (buried arc state), it is easy to achieve through welding.

  On the other hand, when through-welding is achieved in this way, one of the main surfaces of the base material (main surface on the side where the welding wire enters) in which the bead formed by solidification of the molten region is maintained in an unmelted state is maintained. A state (overlap) covering the part may occur. In this case, the main surface of the base material and the bead are not sufficiently bonded. For this reason, the region where the overlap occurs becomes a defect of the bonded body, which may reduce the strength of the bonded body. According to the study by the present inventors, the arc is formed while the tip position of the welding wire reciprocates in the thickness direction of the first base material and the second base material, thereby suppressing the occurrence of overlap. However, through welding can be achieved. That is, when the welding wire penetrates deeply (to the second depth), the heat of the arc is applied to a region far from the main surface of the base material on the side where the welding wire penetrates, contributing to the achievement of through welding. When the welding wire is shallow (up to the first depth), arc heat is applied to a region close to the main surface of the base material on the side where the welding wire enters, and the occurrence of overlap is suppressed. By repeating the state where the welding wire penetrates deeply and the state where the welding wire penetrates shallowly, through welding can be achieved while suppressing occurrence of overlap.

  In the welding method of the present invention, an arc is formed while the position of the tip of the welding wire reciprocates in the thickness direction of the first base material and the second base material in a state where the welding wire has penetrated to the region surrounded by the melting region. Thus, the melting region is formed so as to penetrate the first base material and the second base material in the thickness direction. Therefore, according to the welding method of the present invention, it is possible to improve the work efficiency of welding by achieving through welding in butt welding by GMA welding.

  In the above-described welding method, in the step of welding the first base material and the second base material, the welding wire penetrates to the first depth, and the mode of transition to the melted region formed by melting the welding wire is formed. May be repeated between the state of rotating transition and the state where the welding wire penetrates to the second depth and the transition form is other than the transition of rotating.

  In the state of rotating, the tip of the welding wire rotates around an axis along the thickness direction of the first base material and the second base material. Therefore, the formed arc rotates around the axis. When the welding wire is in a shallow state (up to the first depth) and is shifted to the rotating state, the heat of the arc is easily supplied to a region where the overlap is likely to occur. As a result, the occurrence of overlap is more reliably suppressed.

  In the welding method, in the step of welding the first base material and the second base material, the feeding speed of the welding wire may be 30 m / min or more. By doing in this way, it becomes easy to maintain a buried arc state.

  In the welding method, in the step of preparing the first base material and the second base material, a first base material and a second base material having a thickness of 10 mm to 30 mm may be prepared. The achievement of through welding by GMA welding is particularly effective from the viewpoint of improving work efficiency in a base material having a thickness of 10 mm or more. On the other hand, if the thickness of the base material exceeds 30 mm, it may be difficult to achieve through welding. Therefore, the thickness of the first base material and the second base material may be 10 mm or more and 30 mm or less.

  In the welding method, in the step of welding the first base material and the second base material, the first base material and the second base material in which no groove is formed may be welded.

  According to the welding method of the present invention, it is possible to weld a base material in which no groove is formed. When the groove is formed, it is necessary to fill a region where the groove is formed at the time of welding. Therefore, for example, the distortion of the base material may increase due to an increase in the amount of filler material supplied to the weld. By welding the base material in which no groove is formed by the welding method of the present invention, the occurrence of such a problem can be suppressed.

  In the welding method, the welding wire may be a solid wire. In the welding method of the present invention, it is preferable to use a solid wire.

  In the above welding method, the diameter of the welding wire may be not less than 1.2 mm and not more than 1.6 mm. This makes it easy to maintain a buried arc state during welding.

  As is apparent from the above description, according to the welding method of the present invention, it is possible to provide a welding method capable of improving the work efficiency of welding by achieving through welding in butt welding by GMA welding.

It is a flowchart which shows the outline of the procedure of welding. FIG. 3 is a schematic diagram showing a state before starting welding in the first embodiment. It is the schematic which shows the state which the welding wire penetrate | invaded deeply of the welding process in Embodiment 1. FIG. It is the schematic which shows the state which the welding wire penetrate | invades shallowly and the transfer form of a droplet is rotating transfer in the welding process in Embodiment 1. FIG. It is a timing chart which shows the control state of electric current, a voltage, and the feeding speed of a welding wire. 6 is a schematic diagram showing a state before the start of welding in Embodiment 2. FIG. It is the schematic which shows the state which the welding wire penetrate | invaded deeply of the welding process in Embodiment 2. FIG. It is the schematic which shows the state which the welding wire penetrate | invades shallowly and the transfer form of a droplet is rotating transfer in the welding process in Embodiment 2. FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following drawings, the same or corresponding parts are denoted by the same reference numerals, and description thereof will not be repeated.

(Embodiment 1)
First, the welding method in Embodiment 1 is demonstrated. With reference to FIG. 1, in the welding method of Embodiment 1, a base material preparation process is first implemented as process (S10). In this step (S10), a pair of base materials to be joined by welding is prepared. Specifically, referring to FIG. 2, a first base material 50 and a second base material 60 are prepared. The first base material 50 and the second base material 60 are steel plates made of steel such as mild steel, carbon steel for machine structure, alloy steel for machine structure, for example. The thickness of the steel plate is, for example, 10 mm or more and 30 mm or less.

  Next, a base material arranging step is performed as a step (S20). In this step (S20), referring to FIG. 2, first base material 50 and second base material 60 prepared in step (S10) are set in welding apparatus 100. The welding apparatus 100 includes a torch 19, a power supply 30, and a wire feeding device 29. The torch 19 includes a contact tip 17 and a nozzle 18 having a hollow cylindrical shape surrounding the contact tip 17. The contact chip 17 is made of a conductive material (metal) such as a copper alloy. The contact tip 17 guides the welding wire 15 while being in contact with the welding wire 15 that is a filler material. That is, the welding wire 15 and the contact tip 17 are electrically connected. The welding wire 15 functions as a consumable electrode. In the present embodiment, the welding wire 15 is a solid wire. The diameter of the welding wire 15 is 1.2 mm or more and 1.6 mm or less, for example.

  The nozzle 18 forms a flow path for flowing a shield gas between the nozzle 18 and the contact chip 17. The welding wire 15 is located in a region including the central axis of the nozzle 18. The wire feeding device 29 feeds the welding wire 15 into the nozzle 18. The power supply 30 is electrically connected to the contact chip 17 via the wiring 34. The power supply 30 is electrically connected to the second base material 60 via the wiring 64.

  The first base material 50 has one main surface 52, the other main surface 53, and a first end surface 51. Second base material 60 has one main surface 62, the other main surface 63, and a second end surface 61. The first base material 50 and the second base material 60 are arranged so that the first end face 51 and the second end face 61 face each other. The first base material 50 and the second base material 60 are arranged so that the first end face 51 and the second end face 61 are in contact with each other. No groove is formed in the first base material 50 and the second base material 60. That is, the first end surface 51 and the second end surface 61 are parallel throughout the entire thickness direction.

  Next, a welding process is performed as a process (S30). In this step (S30), the first base material 50 and the second base material 60 arranged in step (S20) are welded by GMA welding. Specifically, referring to FIGS. 3 and 4, the welding wire 15 is fed by the wire feeding device 29, and the first preform 50, the second preform 60, and the welding wire 15 are supplied by the power source 30. When a voltage is applied between them, the arc 11 is formed between the welding wire 15 and the first base material 50 and the second base material 60. At this time, for example, a shielding gas such as carbon dioxide gas is supplied into the nozzle 18 and flows through the space between the contact tip 17 and the inner peripheral surface of the nozzle 18. And shield gas is discharged along the arrow G from the exit of the nozzle 18, and the arc 11 and external air are interrupted | blocked. The molten region 12 is formed in the first base material 50 and the second base material 60 by the heat of the arc 11 formed in this way.

  At this time, the position of the tip 15A of the welding wire 15 is in the thickness direction of the first base material 50 and the second base material 60 with the welding wire 15 penetrating into the region surrounded by the melting region 12 (buried arc state). The arc 11 is formed while reciprocating between the first depth and the second depth deeper than the first depth, so that the melting region 12 causes the first base material 50 and the second base material 60 to move in the thickness direction. It is formed so as to penetrate through. That is, in a state where the tip 15A of the welding wire 15 that has entered from one main surface 52 of the first base material 50 and one main surface 62 of the second base material 60 is located in a region surrounded by the melting region 12. The arc 11 is formed while the position of the tip 15 </ b> A reciprocates in the thickness direction of the first base material 50 and the second base material 60. The molten region 12 is exposed on the other main surface 53 of the first base material 50 and the other main surface 63 of the second base material 60.

A more specific control method will be described with reference to FIGS. In FIG. 5, the horizontal axis corresponds to time t. The vertical axis corresponds to the feed rate W _f of the welding current I, welding voltage V and welding wire 15 in FIG. Referring to FIGS. 3 to 5, the current I is controlled to repeat a state of high _{I H} than state and _{I TH} lower _{I L} than the threshold current _{I TH.} Between time _{t 1} the current I is in the state of the _{I H} at time _{t 2} (time _T H), the voltage V is _{V H,} the feeding rate _{W f} is the _{W fH.} Between time _{t 2} the current I is the state of _{I L} at time _{t 3} (time _T L), the voltage V is lower _{V L} than _{V H,} feed rate _{W f} is smaller than _{W fH W fL} It is said. The sum of the time _TH and the time _TL is the time T per cycle. The reciprocal 1 / T of T is the frequency. The frequency 1 / T can be, for example, 0.2 Hz or more and 2 Hz or less.

In a state where the current I is smaller than the threshold current _ITH , as shown in FIG. 3, the welding wire 15 has entered deeply (to the second depth) in the thickness direction of the first base material 50 and the second base material 60. It becomes. At this time, the transition form to the melted region 12 of the fusion formed by melting the welding wire 15 is a state other than the rotational transition, for example, a drop transition state, or the tip 15A of the welding wire 15 moves in a pendulum shape. It becomes the state transition (pendulum transition) state. On the other hand, in the state where the current I is larger than the threshold current _ITH , the welding wire 15 is shallow in the thickness direction of the first base material 50 and the second base material 60 (up to the first depth) as shown in FIG. Will be in a state. At this time, the mode of transition to the melted region 12 of the fusion formed by melting the welding wire 15 is a state of rotating transition.

  In the state of rotating transition, the region near the tip 15A of the welding wire 15 is curved so as to be separated from the axis α along the thickness direction of the first base material 50 and the second base material 60. Then, the tip 15A of the welding wire 15 rotates around the axis α. Therefore, the formed arc 11 rotates around the axis α. When the welding wire 15 enters a state where the welding wire 15 has entered shallowly and is in a state of shifting to a rotating state, an area where the occurrence of overlap is a concern (one main surface 52 of the first base material 50 and one main surface of the second base material 60). It becomes easy to supply the heat of the arc 11 to a region close to the surface 62.

  As the torch 19 moves relative to the first base material 50 and the second base material 60, the region where the melted region 12 is formed moves. The previously formed molten region 12 solidifies as the temperature decreases. In this embodiment, the melted region 12 is sequentially formed along the extending direction of the region to be welded (the region where the first end surface 51 and the second end surface 61 face each other), and the formed melted region 12 is solidified. The welding of the first base material 50 and the second base material 60 in the form is completed.

  In the welding method according to the present embodiment, in the step (S30), the position of the tip 15A of the welding wire 15 is the first base material 50 and the second base material 50 in a state where the welding wire 15 has penetrated to the region surrounded by the melting region 12. The arc 11 is formed while reciprocating between the first depth and the second depth deeper than the first depth in the thickness direction of the base material 60, so that the melting region 12 is formed in the first base material 50 and the first base material 60. It is formed so as to penetrate the two base materials 60 in the thickness direction.

  At this time, the welding wire 15 penetrates shallowly (to the first depth) in the thickness direction of the first base material 50 and the second base material 60, and the welding wire 15 melts to the melting region 12 formed by melting. The transition form is a state of transition to rotating, and the welding wire 15 penetrates deeply (to the second depth), and the transition form is repeated in a state other than the transition of rotating. By forming the arc 11 with the welding wire 15 penetrating deeply, the heat of the arc 11 is in a region close to the other main surface 53 of the first base material 50 and the other main surface 62 of the second base material 60. Supplied. Therefore, it is easy to achieve through welding. On the other hand, when the welding wire 15 enters a state where the welding wire 15 has entered shallowly, the region where the occurrence of overlap is likely to occur (one main surface 52 of the first base material 50 and one of the second base materials 60). The heat of the arc 11 is easily supplied to the region near the main surface 62. Therefore, the occurrence of overlap is suppressed. And by repeating these states, through welding can be achieved while suppressing the occurrence of overlap. Therefore, according to the welding method of the present embodiment, it is possible to improve the work efficiency of welding by achieving through welding in butt welding by GMA welding.

  In the said process (S30), it is preferable that the feeding speed of a welding wire shall be 30 m / min or more. Thereby, it becomes easy to maintain a buried arc state.

(Embodiment 2)
Next, the welding method in Embodiment 2, which is another embodiment of the present invention, will be described. The welding method according to the second embodiment is basically performed in the same manner as in the first embodiment, and has the same effects. However, the welding method of the second embodiment is different from that of the first embodiment in the shape of the end face of the base material.

  Referring to FIG. 6, in the welding method according to the second embodiment, in step (S10), first base material 50 and second base material 60 in which groove 70 is formed are prepared. The groove 70 is formed on one main surface 52, 62 side of the first base material 50 and the second base material 60. The groove 70 includes a corner portion of the first base material 50 to which the first end surface 51 and the one main surface 52 are connected, and a second base material 60 to which the second end surface 61 and the one main surface 62 are connected. It is formed so as to remove the corners. Therefore, in the step (S20), when the first base material 50 and the second base material 60 are arranged so that the first end face 51 and the second end face 61 face each other, in the region corresponding to the groove 70, The distance between the first base material 50 and the second base material 60 increases as the main surfaces 52 and 62 are approached.

  In step (S30), referring to FIGS. 7 and 8, first base material 50 and second base material 60 are welded in a state where groove 70 is formed. At this time, the region corresponding to the groove 70 is filled by welding. That is, the amount of the welding wire 15 as the filler material supplied to the melting region 12 is increased as compared with the first embodiment in which the groove 70 is not formed.

  Thus, by forming the groove 70, it becomes easy to achieve through welding in the step (S30). Therefore, when the first base material 50 and the second base material 60 having a large thickness are welded, the welding method of the present embodiment is suitable.

  In the above embodiment, the welding current, welding voltage, and welding wire feeding speed are increased to allow the welding wire to enter shallowly, and the welding current, welding voltage, and welding wire feeding speed are decreased. Although the method of reciprocating the position of the tip of the welding wire in the thickness direction of the base material by setting the welding wire to enter deeply has been described, the welding method of the present invention is not limited to this. For example, under a constant welding voltage, the welding wire feed speed and welding current are increased so that the welding wire penetrates deeply, and the welding wire feeding speed and welding current is reduced to enter the welding wire shallowly penetrating. By doing so, the position of the tip of the welding wire may be reciprocated in the thickness direction of the base material.

  An experiment was conducted to confirm that through welding in butt welding can be achieved by GMA welding with the welding method of the present invention. The specific experimental method is as follows.

  First, two steel plates with a thickness of 12 mm were prepared as base materials. Next, referring to FIG. 2, as in the case of the first embodiment, two steel plates were set in welding apparatus 100 so that the end surfaces of the two steel plates contact each other without forming a groove. And welding was implemented on the conditions shown in Table 1.

溶接により接合された鋼板を観察した結果、貫通溶接が達成されていることが確認された。また、オーバーラップの発生は確認されなかった。以上の実験結果から、本発明の溶接方法によれば、溶接ワイヤが深く侵入した状態と浅く侵入した状態とが繰り返されることにより、オーバーラップの発生を抑制しつつ貫通溶接を達成することができることが確認される。

As a result of observing the steel plates joined by welding, it was confirmed that through welding was achieved. Moreover, the occurrence of overlap was not confirmed. From the above experimental results, according to the welding method of the present invention, it is possible to achieve through welding while suppressing the occurrence of overlap by repeating the state where the welding wire penetrates deeply and the state where the welding wire penetrates deeply. Is confirmed.

  It should be understood that the embodiments and examples disclosed herein are illustrative in all respects and are not restrictive in any respect. The scope of the present invention is defined by the scope of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the scope of the claims.

  The welding method of the present invention can be applied particularly advantageously to welding that requires improvement in work efficiency.

  11 arc, 12 melting region, 15 welding wire, 15A tip, 17 contact tip, 18 nozzle, 19 torch, 29 wire feeder, 30 power supply, 34 wiring, 50 first base material, 51 first end face, 52, 53 Main surface, 60 2nd base material, 61 2nd end surface, 62, 63 Main surface, 64 wiring, 70 groove, 100 Welding device.

Claims (7)

Preparing a first base material and a second base material;
Disposing the first base material and the second base material such that the first end surface of the first base material and the second end surface of the second base material face each other;
Welding the first base material and the second base material by GMA welding so that the first end face and the second end face are joined,
In the step of welding the first base material and the second base material, an arc is formed between a welding wire, the first base material, and the second base material, and the first base material is generated by heat of the arc. The first base material and the second base material are welded by forming a melting region in the material and the second base material,
In the step of welding the first base material and the second base material, the position of the tip of the welding wire is the first base material and the welding wire in a state where the welding wire has penetrated to the region surrounded by the melting region. The arc is formed while reciprocating between a first depth and a second depth deeper than the first depth in the thickness direction of the second base material, so that the melting region is the first base material. The welding method formed so that a material and the said 2nd base material may be penetrated in the thickness direction.   In the step of welding the first base material and the second base material, the welding wire penetrates to the first depth, and the excision formed by melting the welding wire is transferred to the melting region. The welding method according to claim 1, wherein the state is a state of transition to rotation and the welding wire penetrates to the second depth, and the state of transition is a state other than the transition of rotation.   The welding method according to claim 1 or 2, wherein, in the step of welding the first base material and the second base material, a feeding speed of the welding wire is 30 m / min or more.   4. The method according to claim 1, wherein in the step of preparing the first base material and the second base material, the first base material and the second base material having a thickness of 10 mm to 30 mm are prepared. The welding method as described in.   5. The method according to claim 1, wherein in the step of welding the first base material and the second base material, the first base material and the second base material in which no groove is formed are welded. The welding method according to Item 1.   The welding method according to claim 1, wherein the welding wire is a solid wire. The welding method according to claim 1, wherein a diameter of the welding wire is 1.2 mm or greater and 1.6 mm or less.

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