JP2013099755A - Arc welding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an arc welding method which can stabilize a shape of a molten ball to stabilize weld strength.SOLUTION: In the TIG welding that causes arc discharge to be generated between conductors 20, 21 and an electrode 12 to perform welding, a welding current is temporarily reduced so that arc pressure that acts on ends 20a, 21a of the conductors 20, 21 during discharge is temporarily reduced in the middle of discharge to integrate together molten metals that are independently melted in respective conductors 20, 21.

Description

  The present invention relates to an arc welding method for performing welding using arc discharge. More specifically, the present invention relates to a non-consumable electrode type arc welding method capable of stabilizing the shape of a molten ball during welding.

  The ends of other coil wires, connection terminals, and the like are connected to the ends of the coil wires constituting the coil mounted on the stator or the like. In this connection portion, both members are welded and electrically connected. Such welding is performed by, for example, TIG welding (see Patent Document 1).

  When joining the coil wires by TIG welding, the tip of the coil wire to be joined is held and the electrode is brought close to the end of the coil wire. Then, by passing a constant current through the end of the coil wire (controlling the welding current at a constant value), the coil wire is melted by the high heat generated by the arc generated between the coil wire and the electrode. As a result, the coil wires are fused and integrated at the molecular atom level.

JP 2008-243870 A

  However, the above-described welding method has a problem that welding failure such as melting and distortion of the shape of the welded portion occurs and the welding strength after joining is not stable. This was found to be due to the following reasons. That is, in non-consumable electrode type arc welding such as TIG welding, a large arc pressure generated during welding acts on the end of the coil wire, so that the molten metal is pushed away and joined as shown in FIG. Since the molten metal moves in a direction away from the molten metal, it is difficult to form a molten ball. For this reason, melting and splitting may occur.

  Then, when the volume of the molten metal increases, if the molten ball is connected to one ball and a molten ball is formed, melting does not occur. However, when the molten metal is connected to one ball, The molten pool shakes up and down and right and left. Depending on the behavior of the molten pool, the shape of the welded portion may be distorted depending on the conditions at which the molten pool solidifies.

  Accordingly, the present invention has been made to solve the above-described problems, and an object thereof is to provide an arc welding method capable of stabilizing the welding strength by stabilizing the shape of the molten ball.

  One aspect of the present invention made to solve the above problems is a non-consumable electrode type arc welding method in which arc discharge is generated between a member to be welded and an electrode to perform welding. The arc pressure acting on the gas is temporarily reduced during the discharge, and melted and independent molten metals are integrated for each member to be welded.

  In this arc welding method, molten metal that is melted and independent for each member to be welded is integrated in the course of welding to form a molten ball, and therefore when the independent molten metal is connected to one ball. It is possible to prevent the molten pool formed on the surface from shaking greatly. Thereby, while being able to stabilize the shape of a molten ball, generation | occurrence | production of melting and splitting can be prevented reliably. As a result, the welding strength after joining can be stabilized.

  In the arc welding method described above, the time for reducing the arc pressure may be 1/20 to 1/3 of the welding time (total energization time).

  This is because by setting the arc pressure drop time to the above-described time, the shape of the molten ball can be reliably stabilized and the occurrence of melting can be reliably prevented. If the arc pressure drop time is shorter than 1/20 of the welding time, there is a possibility that an independent molten metal cannot be connected to one ball. Since the production efficiency is lowered simply by increasing the arc length, the arc pressure drop time is set in the above-described range.

  In the arc welding method described above, it is desirable to reduce the arc pressure by reducing the welding current while keeping the welding voltage constant.

  Since the arc pressure is generally amplified by the square of the current value, the arc pressure can be temporarily reduced easily and reliably by reducing the welding current while keeping the welding voltage constant. Thereby, it is possible to form molten balls by integrating molten metals that are melted and independent for each member to be welded during welding. As a result, the shape of the molten ball can be stabilized and the occurrence of melting can be reliably prevented, so that the welding strength after joining can be stabilized.

  Then, the welding current may be reduced to 50% or less of the maximum value. In this case, 0 A is not included in the welding current value. This is because when the welding current is 0 A, the arc disappears and welding cannot be performed.

  The reason for this is that if the current value when the welding current is reduced is greater than 50% of the maximum value, the arc pressure cannot be sufficiently reduced, and the molten pool may be greatly shaken vertically and horizontally. Because there is.

  In the arc welding method described above, the arc pressure acting on the member to be welded may be reduced by shifting the irradiation position of the arc on the member to be welded.

Specifically, at least one of the electrode and the member to be welded may be shifted in a direction orthogonal to the arc irradiation direction. Further, the member to be welded may be vibrated. Even if it does in this way, the arc pressure which acts on a to-be-welded member can be reduced, and the above-mentioned effect can be acquired.
In addition, the range which shifts an electrode or a member to be welded needs to be within 0.5 mm width (1.0 mm in the range) from the original position (reference position). This is because if the position is further shifted, the member to be welded cannot be welded. Even when the member to be welded is vibrated, it is necessary to set the amplitude within the same range.

  Alternatively, in the arc welding method described above, the arc pressure acting on the member to be welded may be reduced by increasing the distance between the member to be welded and the electrode in the arc irradiation direction.

Specifically, at least one of the electrode and the member to be welded may be moved in the arc irradiation direction so that the distance between them is increased. Even if it does in this way, the arc pressure which acts on a to-be-welded member can be reduced, and the above-mentioned effect can be acquired.
In addition, the distance which moves an electrode or a to-be-welded member needs to be less than 0.5 mm from the original position (reference | standard position). This is because if it is moved beyond this, the member to be welded cannot be welded.

  According to the arc welding method of the present invention, as described above, the welding strength can be stabilized by stabilizing the shape of the molten ball.

It is a schematic block diagram which shows the outline of a welding apparatus. It is a figure which shows typically the mode of the welding part at the time of welding. It is a figure which shows the change of a welding current, and the state change of a fusion pool. It is a figure for demonstrating a 1st modification. It is a figure for demonstrating a 2nd modification. It is a figure which shows an example in the case of welding a conducting wire and a terminal. It is a figure which shows the change of the welding current in the conventional welding method, and the state change of a fusion pool.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying the arc welding method of the present invention will be described below in detail with reference to the drawings. Here, in order to join two conductors, the case where the end part is TIG-welded is illustrated.

  First, a schematic configuration of a welding apparatus that performs the TIG welding method according to the present embodiment will be briefly described with reference to FIGS. 1 and 2. FIG. 1 is a schematic configuration diagram showing an outline of a welding apparatus. FIG. 2 is a diagram schematically showing the state of the welded part during welding.

  As shown in FIG. 1, the welding apparatus 10 includes a welding torch electrode 12 connected to the negative electrode side of the power supply control unit 11 and a positive electrode side of the power supply control unit 11 between the conductors 20 and 21. An electrode 13 for generating arc discharge is provided. A predetermined interval is formed between the conductors 20 and 21 and the electrode 12 in a state where the ends of the electrodes 13 are aligned with the conductors 20 and 21 and the end portions 20a and 21a are sandwiched and adhered. Thus, the conductors 20 and 21 are fixed. As a result, the conductors 20 and 21 are connected to the positive electrode side of the power supply control unit 11 via the electrode 13, and the center axis L of the electrode 12 of the welding torch and the center C of the boundary between the conductors 20 and 21 coincide with each other. To do.

  The conductors 20 and 21 are electric wires coated with an insulator (enamel), and at the ends 20a and 21a, the insulator is peeled to expose the conductor. The conductors 20 and 21 are flat rectangular conductors made of copper and having a rectangular cross-sectional shape. In addition, the conductor used as welding object may be comprised by the round wire with the circular cross-sectional shape.

  Then, the power source controller 11 energizes the conductors 20 and 21 through the electrode 13 to generate an arc 14 between the electrode 12 and the conductors 20 and 21 as shown in FIG. The arc 14 is an arc discharge that flows between the electrode 12 and the conductors 20 and 21, and is a flow of charged particles in a high-temperature plasma state. By this arc 14, the conductor 20 and the conductor 21 are TIG welded. That is, the end portions 20a and 21a of the conductors 20 and 21 are heated to a high temperature and melted by the arc 14, and the conductor 20 and the conductor 21 are integrated and joined at the end portions 20a and 21a.

  Here, in the conventional TIG welding, as described above, due to the large arc pressure generated during welding (see the arrow in FIG. 2), the molten metal is pushed away and the molten metal to be joined is separated. It moves. Therefore, poor welding has occurred due to the difficulty of forming molten balls.

  Therefore, in the welding method according to the present embodiment, in order to stabilize the shape of the molten ball, the arc pressure acting on the end portions 20a, 21a of the conductors 20, 21 is temporarily reduced during welding as follows. I am letting. This welding method will be described with reference to FIG. FIG. 3 is a diagram showing changes in welding current and changes in the state of the molten pool. The change in the state of the molten pool was confirmed by photographing the state of TIG welding with a high-speed camera.

  In the welding method according to the present embodiment, as shown in FIG. 3, the arc current is reduced by temporarily reducing the welding current during welding. The voltage value is constant. Specifically, when welding is started, a predetermined current flows through the conductors 20 and 21, and an arc 14 is generated. As a result, the ends 20a and 21a of the conductors 20 and 21 are heated to a high temperature by the arc 14 and start to melt. At this time, as shown to Fig.3 (a), the metal fuse | melted in edge part 20a, 21a is in the state which was mutually independent (it is not connected). And with time progress, the quantity of the molten metal in the edge parts 20a and 21a increases (refer FIG.3 (b)). At this time, the molten metals at the end portions 20a and 21a are in an independent state.

  And welding current is reduced temporarily. Since the arc pressure is generally amplified by the square of the current value, the arc acting on the ends 20a and 21a of the conductors 20 and 21 can be easily and reliably reduced by reducing the welding current while keeping the welding voltage constant. The pressure can be temporarily reduced. Thereby, as shown in FIG.3 (c), since the metal fuse | melted in the edge parts 20a and 21a becomes difficult to receive to the influence of an arc pressure, it connects and it becomes one molten ball. At this time, since the arc pressure acting on the end portions 20a and 21a of the conductors 20 and 21 is small, the molten pool does not shake greatly. Thereby, while being able to stabilize the shape of a molten ball, generation | occurrence | production of melting and splitting can be prevented reliably.

  Here, the time for reducing the arc pressure, in other words, reducing the welding current may be 1/20 to 1/3 of the welding time (total energization time). If the current reduction time is shorter than 1/20 of the welding time, molten metal may not be connected to a single ball. On the other hand, even if the current reduction time is increased, the welding efficiency only increases and the production efficiency decreases. Because it does. Specifically, since the total energization time is several hundred msec, the current reduction time is about 10 msec to 100 msec. For example, if the total energization time is about 300 msec, the current reduction time may be set to about 50 msec.

  In this way, by reducing the welding current for a certain time, the metal melted at the ends 20a and 21a of the conductors 20 and 21 can be reliably connected and the shape can be stabilized as one molten ball, The occurrence of separation can be reliably prevented.

The welding current can be reduced by reducing the welding current to 50% or less of the maximum value. The reason for this is that if the current value when the welding current is reduced is greater than 50% of the maximum value, the arc pressure cannot be sufficiently reduced, and the molten pool may be greatly shaken vertically and horizontally. Because there is. Specifically, since the welding current value is about 50 to 200 A, the reduced current value is about 25 to 100 A. For example, if the welding current value is about 100 A, the reduced current value may be set to about 25 to 50 A.
Note that the current value is not set to 0 A when the welding current is reduced. This is because when the welding current is set to 0 A, the arc disappears and welding cannot be performed.

  Then, the welding current value is again increased to a predetermined value. Then, the volume of the molten pool increases according to the energization time. At this time, the arc pressure increases again, but the metal melted at the end portions 20a and 21a of the conductors 20 and 21 is one molten ball, so that the molten pool is greatly shaken under the influence of the arc pressure. No (see FIG. 3D). In addition, the energization time (time from the end of current reduction control to the end of welding) at this time may be about 100 msec to 500 msec.

Thereafter, energization is terminated and welding is completed. If it does so, the temperature of the edge parts 20a and 21a of the conductors 20 and 21 will fall, a molten pool will solidify, and the conductor 20 and the conductor 21 will be joined (refer FIG.3 (e)).
As described above, in the welding method according to the present embodiment, the molten metal at the end portions 20a and 21a of the conductors 20 and 21 can be reliably connected to form one molten ball, and the molten pool can be shaken greatly. And the molten pool can be stabilized and solidified. Therefore, it is possible to always ensure good welding quality and to stabilize the welding strength.

  Here, in the welding method described above, the arc pressure acting on the conductor end is reduced by reducing the welding current, but the arc pressure can also be reduced as follows. Therefore, a modification of the welding method will be described with reference to FIGS. FIG. 4 is a diagram for explaining the first modification. FIG. 5 is a diagram for explaining the second modification.

First, in the first modified example, the arc pressure acting on the end portions 20a and 21a of the conductors 20 and 21 is reduced by shifting the irradiation position of the arc on the conductors 20 and 21. That is, as shown in FIG. 4, at least one of the electrode 12 or the conductors 20 and 21 is shifted in a direction in which the central axis L of the electrode 12 and the center C of the boundary between the conductors 20 and 21 are orthogonal to the arc irradiation direction. You can do it. Thereby, the arc pressure acting on the end portions 20a and 21a can be reduced, and the above-described effects can be obtained.
Further, even if the conductors 20 and 21 are vibrated in the left-right direction in the figure, the arc pressure acting on the end portions 20a and 21a can be reduced.

  In this first modification, the range in which the electrode 12 or the conductors 20 and 21 are displaced (the amount of deviation between the center axis L and the center C) is within 0.5 mm (1.0 mm in the range) in the left-right direction in the figure. There is a need to. This is because the conductor 20 and the conductor 21 may not be welded if they are shifted beyond this. Also, when the conductors 20 and 21 are vibrated, it is necessary to set the amplitude within the same range.

  Next, in the second modification, the arc pressure acting on the end portions 20a, 21a of the conductors 20, 21 by separating the distance between the end portions 20a, 21a of the conductors 20, 21 and the electrode 12 in the arc irradiation direction. Is reduced. That is, as shown in FIG. 5, at least one of the electrode 12 or the conductors 20 and 21 may be moved in the arc irradiation direction (vertical direction in the figure) so that the distance between them is increased. Thereby, the arc pressure acting on the end portions 20a and 21a can be reduced, and the above-described effects can be obtained.

  In the second modification, the distance for moving the electrode 12 or the conductors 20 and 21 needs to be within 0.5 mm from the original position (reference position). This is because the conductor 20 and the conductor 21 cannot be welded if they are moved further.

  As described above, according to the welding method of the present embodiment as described in detail, the arc pressure acting on the end portions 20a and 21a of the conductors 20 and 21 is reduced during welding, and the conductors 20 and 21 are melted. Since the molten metals that are independent are integrated to form a molten ball, it is possible to prevent a large swinging movement of the molten pool when the molten metal is connected to one ball. Therefore, the shape of the molten ball can be stabilized and the occurrence of melting can be reliably prevented, so that the welding strength after joining can be stabilized.

It should be noted that the above-described embodiment is merely an example and does not limit the present invention in any way, and various improvements and modifications can be made without departing from the scope of the invention. For example, in the above-described embodiment, the case where the present invention is applied when two conductors are joined is illustrated, but three or more conductors can be joined.
Further, the present invention can be applied not only to joining conductors but also to joining conductors 20 and terminals (bus bars) 25 as shown in FIG.
Furthermore, the present invention can also be applied to welding (joining) metal materials other than conductors and terminals.

10 TIG Welding Device 11 Power Supply Control Unit 12 Electrode (Negative Electrode Side)
13 Electrode (Positive electrode side)
14 Arc 20 Conductor 20a End 21 Conductor 21a End C Center L Center axis

Claims (6)

In a non-consumable electrode type arc welding method for performing welding by generating arc discharge between a member to be welded and an electrode,
An arc welding method characterized in that an arc pressure acting on a member to be welded during discharge is temporarily reduced during the discharge, and molten metals that are melted and independent for each member to be welded are integrated. In the arc welding method according to claim 1,
The arc welding method characterized in that the time for reducing the arc pressure is 1/20 to 1/3 of the welding time. In the arc welding method according to claim 1 or 2,
An arc welding method characterized by lowering an arc pressure acting on a member to be welded by reducing a welding current while keeping a welding voltage constant. In the arc welding method according to claim 3,
An arc welding method, wherein the welding current is reduced to 50% or less of the maximum value. In the arc welding method according to claim 1 or 2,
An arc welding method characterized by reducing an arc pressure acting on a member to be welded by shifting an irradiation position of the arc to the member to be welded. In the arc welding method according to claim 1 or 2,
An arc welding method characterized by lowering an arc pressure acting on a member to be welded by separating a distance between the member to be welded and an electrode in an arc irradiation direction.

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