JP6994623B2 - Arc start method - Google Patents

Description

The present disclosure relates to an arc start method in which an arc is generated between a welding wire as a consumable electrode and a base metal to be welded to perform welding.

In the conventional arc welding, as shown in FIG. 5, the main welding average current IN is performed from the welding start portion. In the above-mentioned conventional arc welding, when a base metal having high thermal conductivity and low intrinsic resistivity such as aluminum is welded at the welding start portion, insufficient penetration may occur due to insufficient heat input near the welding start portion. be. The bead width is narrow, the bead height is high, the penetration is shallow, and the bead appearance may be unfamiliar to the bead.

For the above solution, in the arc start welding method using the semi-automatic arc welding device, as shown in FIG. 6, after the initial welding average current is held for a predetermined time during the arc start period, the main welding average current is operated by the operator's torch switch operation. Welding conditions were switched to.

Further, in the arc start welding method using an automatic welding device (robot), as shown in FIG. 6, in the arc start period TS, the initial welding average current IS larger than the main welding average current IN of the main welding period TN is the initial welding average. It is disclosed that the output is output in the current holding period TS2 and is controlled by moving from the welding start position which is the welding start portion at a speed smaller than the welding speed of the main welding period TN (for example, Patent Document 1).

International Publication No. 2008/0474888

In the arc start welding method when welding a base metal with high thermal conductivity and low intrinsic resistance such as aluminum in a conventional semi-automatic arc welding device, as shown in FIG. 6, the book of the main welding period during the arc start period. After holding the initial welding average current larger than the welding average current for a predetermined time, the welding conditions were switched to the average main welding current by operating the torch switch of the operator. Therefore, there are large variations depending on the welding environment such as the operator, base metal shape, plate thickness, welding speed, etc., causing melt-down and insufficient penetration, making it difficult to select welding conditions to ensure welding quality. rice field.

Further, during the arc start period, by steeply increasing the welding current increase slope as shown in FIGS. 6 and 7, the arc becomes unstable and short circuits increase, so that heat input decreases and the amount of penetration decreases. do. Further, since the thermal conductivity is high, the heat input at the welding start position is reduced and the penetration amount is also reduced by slowing the welding current increase inclination.

In order to solve the above problems, in the arc start method of the present disclosure, the material of the welding wire or the base material is mainly aluminum, and the peak current and the base current are pulsed between the welding wire and the base material. It is an arc start method of arc welding that shifts from the arc start period to the main welding period, in which the pulse current is time-averaged and a constant welding average current during the arc start period is obtained. Heat input control higher than the main welding average current in the main welding period is performed for a predetermined time, and after the predetermined time elapses, the main welding period is entered, the heat input amount in the arc start period is determined in advance, and in the arc start period. The increase slope and / or the decrease slope of the welding current during the arc start period is determined so as to have the welding average current and the heat input amount, and the holding time of the welding average current during the arc start period is 200 msec or more and 400 msec. If it is less than, the magnification of the welding average current during the arc start period with respect to the main welding average current is 1.2 times or more and 2.2 times or less with respect to the main welding average current during the main welding period. When the holding time of the welding average current during the arc start period is 400 msec or more and 1500 msec or less, the ratio of the welding average current to the main welding average current during the arc start period is the main welding average current during the main welding period. 1 . This is an arc start method within the range of the value shown by 0008X + 2.5273.

According to the present disclosure, even when welding a base metal having high thermal conductivity and low resistivity such as aluminum, a sufficient amount of penetration can be secured at the welding start position during the arc start period, and the molten pool is stable. It is possible to shift to main welding in this state.

The figure which shows the schematic structure of the arc welding apparatus in this embodiment. (A) A diagram showing a time change of a welding current in the present embodiment, and (b) a diagram showing a torch switch operation in the embodiment. The figure of each welding condition in the arc start period TS of this embodiment and the range which shows the result. A range diagram showing each welding condition and the result in the arc start period TS of the embodiment. (A) A diagram showing a time change of a conventional welding current, (b) a diagram showing a conventional torch switch operation. The figure which shows the time change of the welding current in the conventional automatic welding apparatus. (A) A diagram showing the time change of the welding current in the conventional semi-automatic welding device, (b) A diagram showing the switching of the welding current by operating the torch switch in the conventional semi-automatic welding device.

Hereinafter, embodiments of the present disclosure will be described with reference to FIGS. 1, 2, 3, and 4.

FIG. 1 is a diagram showing a schematic configuration of an arc welding apparatus according to an embodiment of the present disclosure. The arc welding device inputs the primary rectifying unit 2 that rectifies the AC power input from the input power supply 1, the switching unit 3 that controls the welding output, and the output of the switching unit 3 to convert the power into power suitable for welding. A transformer 4 is provided. Further, a secondary rectifying unit 5 that rectifies the secondary output of the transformer 4, a reactor 6 that smoothes the output of the secondary rectifying unit 5, a driving unit 7 that drives the switching unit 3, and welding that detects the welding current. A current detection unit 8 and a welding start determination unit 9 that determines the start of welding from the detected welding current are provided.

Further, it is set by the welding condition setting unit 12 for setting the welding conditions such as the set current, the set voltage, the wire feed amount, the shield gas type, the wire type of the welding wire 17, and the wire diameter, and the welding condition setting unit 12. The storage unit 11 is provided with various parameters such as information, a peak current value for each wire feeding speed, and a base current value. Further, the arc control unit 10 is provided to output a signal for controlling the current and voltage at the time of arc generation based on the output from the storage unit 11.

The drive unit 7 controls the switching unit 3 based on the output of the arc control unit 10. Further, the wire is fed by a wire feeding motor controlled by the welding wire 17 and the wire feeding unit 18. Power for welding smoothed by the reactor 6 is supplied to the welding wire 17 via a tip 14 provided on the torch 13, and an arc 15 is generated between the welding wire 17 and the base metal 16 to perform welding. Will be done.

Further, each component constituting the arc welding apparatus shown in FIG. 1 may be configured individually or may be configured by combining a plurality of components. The operation of the arc welding apparatus configured as described above will be described.

FIG. 2 shows a current value obtained by averaging the pulsed welding currents in the arc start period TS and the present welding period TN in the embodiment of the present disclosure, and is a diagram showing the time change of the welding current. FIG. 3 is a diagram showing welding conditions in each welding period in the arc start period TS, and FIG. 4 is a diagram showing the results.

In the arc start period TS, the welding current is supplied in the welding current increase period TS1 at the welding start portion (not shown) of the base metal 16, and the initial welding average current IS is controlled to gradually increase at a constant rate. When the welding current increase period TS1 is less than 50 msec, the arc becomes unstable due to the steep increase in the welding current I, the short circuit increases, and the heat input decreases. Further, when the welding current increase period TS1 exceeds 400 msec, the heat at the welding start portion is dispersed faster in the base metal having high thermal conductivity such as aluminum than in the base metal such as iron, which is sufficient for the welding start portion. Heat cannot be applied and the heat input decreases.

Therefore, the welding current increase period TS1 reaches the initial welding average current IS in the range of 50 msec or more and 400 msec or less, so that even a base material having high thermal conductivity such as aluminum can be transferred to the base material 16 in the welding current increase period TS1. The heat input is good and the welding condition is stable.

Next, in the arc start period TS, the schematic configuration of the arc welding apparatus of FIG. 1 with respect to the output values and output timings of the welding current increase period TS1, the initial welding average current holding period TS2, the welding current decrease period TS3, and the initial welding average current IS. Will be described using. The welding current detection unit 8 detects the current, the welding start determination unit 9 determines the start of welding, and at the same time, the welding condition setting unit 12 determines the main welding average current IN, and the storage unit 11 determines the main welding average current IN. The welding current increase period TS1, the initial welding average current holding period TS2, the welding current decrease period TS3, and IS associated with are determined and output to the arc control unit 10.

Further, in the initial welding average current holding period TS2 in the arc start period, the initial welding average current IS higher than the main welding average current IN of the main welding period TN is controlled to be output for a certain period of time.
When the initial welding average current holding period TS2 is 200 msec or more and less than 400 msec, the initial welding average current IS in the arc start period is 1.2 times or more the main welding average current IN in the main welding period TN. When it is 2 times or less and the initial welding average current holding period TS2 in the arc start period is 400 msec or more and 1500 msec or less, the initial welding average current IS in the arc start period is the main welding average current IN in the main welding period TN. The range is 1.2 times or more, the initial welding average current IS is Y, the initial welding average current holding period TS2 is X, and Y = −0.0008X + 2.5273 or less. By setting to, the heat input to the base metal 16 during the initial welding average current holding period TS2 becomes good, and it is sufficient for the base metal such as aluminum, which has high heat conductivity and easily disperses heat to the welding point. Welding can be obtained, and even for a base material having a low melting point and liable to cause leaching, it is possible to prevent leaching due to excessive heat input, and it is possible to form a uniform bead width.

Next, in the welding current reduction period TS3 in the arc start period TS, the initial welding average current IS is controlled to gradually decrease to the main welding average current IN at a constant rate. In the welding current reduction period TS3, the heat input is insufficient when it is less than 400 msec, and in the initial welding average current holding period TS2, the main welding period shifted from the arc start period because the heat input to the welding start position is sufficiently applied. The molten metal of the TN is pulled toward the welding start position, the bead width near the welding start position is wide, and the bead at the start portion of the main welding period TN becomes relatively thin, that is, a constricted bead is formed. .. When the welding current reduction period TS3 exceeds 1000 msec, melt-off is likely to occur in the main welding period TN due to excessive heat input to a base material having a low melting point such as aluminum.

Therefore, by setting the welding current reduction period TS3 so as to reach the main welding average current IN in the range of 400 msec or more and 1000 msec or less, the heat input in the welding current reduction period TS3 becomes good, and the bead width becomes uniform. Can be stably secured.

As described above, in the arc start method of the present disclosure of the present disclosure, the material of the welding wire or the base metal is mainly aluminum, and the peak current and the base current are supplied in a pulse shape between the welding wire and the base metal for welding. The initial heat input control in which the initial welding average current in the arc start period is higher than the main welding average current in the main welding period is performed for a predetermined time, and after the predetermined time elapses, the main welding period TN is performed. be.

In addition to the above, the heat input amount during the arc start period is determined in advance, and the increase slope and / or decrease slope of the welding current during the arc start period is determined so as to be the initial welding average current and heat input amount during the arc start period. Is what you do.

By controlling the welding current in the arc start period TS as described above, appropriate heat input to the base metal is performed at the welding start part, and it is possible to shift to the main welding period TN in a stable state of the molten pool. , The main welding can be stabilized. In addition, by eliminating the switching of welding conditions to average main welding by operating the torch switch, there is no variation among workers, and welding is performed even when welding a base metal with high thermal conductivity and low resistivity such as aluminum. Quality can be ensured.

Since uniform welding quality can be ensured in the arc welding control method and the semi-automatic arc welding apparatus, it is industrially useful as an arc welding control method and an arc welding apparatus.

1 Input power supply 2 Primary rectifying unit 3 Switching unit 4 Transformer 5 Secondary rectifying unit 6 Reactor 7 Drive unit 8 Welding current detection unit 9 Welding start determination unit 10 Arc control unit 11 Storage unit 12 Welding condition setting unit 13 Torch 14 Chip 15 Arc 16 Base metal 17 Welding wire 18 Wire feeder IN Main welding average current IS Initial welding average current TN Main welding period TS Arc start period TS1 Welding current increase period TS2 Initial welding average current holding period TS3 Welding current decrease period

Claims (5)

The main material of the welding wire or base metal is aluminum, and welding is performed by supplying a pulsed current with a pulsed peak current and base current between the welding wire and the base metal, and welding is performed from the arc start period. In the arc start method of arc welding that shifts to the welding period, heat input control is performed in which the pulse current is time-averaged and the constant welding average current in the arc start period is higher than the main welding average current in the main welding period. It is performed for a predetermined time, and after the predetermined time has elapsed, the welding period is started.
The amount of heat input during the arc start period is determined in advance, and in the arc start period, the increase slope and / or the decrease slope of the welding current during the arc start period is determined so as to have the welding average current and the heat input amount.
When the holding time of the welding average current during the arc start period is 200 msec or more and less than 400 msec, the ratio of the welding average current to the main welding average current during the arc start period is the main welding average current during the main welding period. When the holding time of the welding average current during the arc start period is 400 msec or more and 1500 msec or less, the welding average current during the arc start period is 1.2 times or more and 2.2 times or less. The magnification with respect to the main welding average current is 1.2 times or more the main welding average current during the main welding period, and the holding time of the welding average current is X, −0 . An arc start method within the range of the value shown by 0008X + 2.5273. The claim that the welding average current is reached in the range of 50 msec or more and 400 msec or less in the increase slope period of the increase slope of the welding current so as to be the welding average current and the heat input amount in the arc start period. 1 The arc start method described. A claim that the main welding average current is reached within the range of 400 msec or more and 1000 msec or less in the decrease inclination period of the decrease inclination of the welding current so as to be the welding average current and the heat input amount in the arc start period. Item 1. The arc start method according to Item 1. The arc start method according to claim 1, wherein the welding average current during the arc start period is in a range of 1.2 times or more and 2.2 times or less with respect to the main welding average current during the main welding period. The arc start method according to claim 1, wherein the holding time of the welding average current during the arc start period is in the range of 200 msec or more and 1500 msec or less.

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