JP2005262264A - Arc start method for consumable electrode gas shielded arc welding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To automatically set an initial time Ti required until the movement of a welding torch starts after arc starting in consumable electrode gas shielded arc welding. <P>SOLUTION: The arc starting method for consumable electrode gas shielded arc welding is provided for starting the movement of the welding torch at a predetermined welding speed vw [mm/s] after a welding current Io starts energizing at the arc starting and after the initial time Ti [s] elapses thereafter, wherein the initial time Ti is set to the time when the initial deposition amount Yi of the welding wire from the point of the time the welding current Io starts energizing attains the reference value Yt obtained by multiplying the stationary deposition amount per unit welding length 1 cm by a coefficient α and the coefficient α is finely adjusted around 0.5 in such a manner that the bead shape of the arc start section attains a desired shape. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an arc start method for consumable electrode gas shield arc welding for improving the welding quality of an arc start portion.

  FIG. 6 is a configuration diagram of a consumable electrode gas shield arc welding apparatus using a welding robot. The manipulator 6 is equipped with a feed motor WM for feeding the welding torch 4 and the welding wire 1. The robot controller 7 outputs an operation control signal Mc for controlling the servo motors of the plurality of axes of the manipulator 6 based on the teaching data. Further, the robot control device 7 transmits a welding condition setting signal including a welding start signal St and a welding speed setting signal vws to the welding power source 5 to start the movement of the welding torch 4 from the welding power source 5 at the time of an arc start. The movement permission signal Wcr is received. That is, the manipulator 6 stops after moving the welding torch 4 to the arc start position, and moves the welding torch 4 at the welding feed vw when the movement permission signal Wcr is input after starting welding. .

  The welding power source 5 is a general power source for consumable electrode gas shielded arc welding, and outputs a welding voltage Vo and a welding current Io for generating the arc 3. Further, the welding power source 5 receives the welding condition setting signal including the welding start signal St and the welding speed setting signal vws, transmits the movement permission signal Wcr, and controls the rotation of the feed motor WM. For this purpose, a feed control signal Fc is output and a feed speed detection signal Fd is received. The welding wire 1 is fed by the feed motor WM, and an arc 3 is generated between the welding wire 1 and the base material 2.

  FIG. 7 is a timing chart at the time of arc start in the above-described welding apparatus. FIG. 4A shows the welding start signal St, FIG. 4B shows the feed control signal Fc, FIG. 4C shows the welding current Io, and FIG. 4D shows the movement permission signal Wcr. (E) shows the time change of the welding speed (welding torch moving speed) vw. Hereinafter, description will be given with reference to FIG.

  At time t1, when the welding start signal St becomes a high level as shown in FIG. 9A, the feed control signal Fc becomes a value corresponding to the initial feed speed Fi as shown in FIG. The welding wire starts to be fed at the initial feeding speed Fi. When the wire tip reaches and contacts the base material at time t2, the welding current Io starts to pass as shown in FIG. At time t3 when a predetermined initial time Ti has elapsed from the start of current application, the movement permission signal Wcr changes to a high level as shown in FIG. In response, the welding torch starts moving at a welding speed vw determined by a predetermined welding speed setting signal vws, as shown in FIG. At the same time, as shown in FIG. 5B, the feed control signal Fc becomes a value corresponding to the steady feed speed Fa, and the welding wire is fed at the steady feed speed Fa. As described above, the welding torch is stopped at the arc start position until the initial time Ti elapses after the welding current Io is applied at time t2 and the arc is generated.

  In the above, the feeding speed during the period from the time t1 to the time t2 is often set to a value (slow down speed) that is lower than the initial feeding speed Fi. Also, the initial feeding speed Fi and the steady feeding speed Fa are often set to the same value.

  There are mainly two reasons for providing the initial time Ti. The first reason is to wait for the movement of the welding torch until the arc state after the current application becomes stable as described in Patent Document 1. If the welding torch starts moving before the arc state is stabilized, the arc state may become unstable due to the movement, and this is to prevent this. The second reason is to improve the bead shape of the arc start portion. FIG. 8 is a schematic view of the bead shape of the arc start portion as seen from the cross section. FIG. 4A shows the case where the initial time Ti is zero, and FIG. 4B shows the case where the initial time Ti is an appropriate value. In the case of FIG. 6A, the bead 2a at the arc start portion has a gentler slope than the bead 2b at the steady portion because the wire welding amount is insufficient. That is, the bead length until the bead shape becomes a steady shape is long. On the other hand, in the case of FIG. 5B, since the welding torch is stopped during the initial time Ti, the welding wire is fed to the arc start portion and the initial welding amount becomes appropriate. For this reason, the bead 2a of the arc start part immediately becomes the same as the bead 2b of the steady part.

Japanese Patent No. 2988176

  FIG. 9 is a bead shape diagram of the arc start portion when the welding conditions are changed. (A) is when the initial time Ti is appropriate, (B) is when the initial time Ti is fixed and the welding speed is increased, and (C) is when the initial time Ti is fixed. This is when the groove shape is widened. As shown in FIG. 5A, if the initial time Ti is an appropriate value, the bead 2a in the arc start portion becomes good. However, as shown in FIG. 5B, when the initial time Ti is fixed and the welding speed is increased, the bead 2a at the arc start portion becomes a slope and the welding quality is deteriorated. Similarly, as shown in FIG. 5C, when the initial time Ti is fixed and the groove of the weld joint is widened, the bead 2a at the arc start portion becomes a slope and the welding quality is deteriorated. Therefore, conventionally, when the welding conditions such as the welding speed, the groove shape, and the steady feeding speed are changed, the initial time Ti has to be set to an appropriate value through trial and error. For this reason, a lot of time is required for the preparation time before welding, and the production efficiency is lowered.

  Therefore, the present invention provides an arc start method for consumable electrode gas shield arc welding that can automatically set the initial time Ti to an appropriate value even if the welding conditions change.

In order to solve the above-described problem, the first invention is that welding is started at a welding speed vw [mm / s] after an initial time Ti [s] has elapsed after the welding current starts energizing at the time of arc start. In the arc start method of the consumable electrode gas shield arc welding that starts the movement of the torch,
The initial time Ti is a time until the initial welding amount Yi of the welding wire from the time when the welding current starts energization to reach the reference value Yt obtained by multiplying the steady welding amount Yc per 1 cm of the welding length by the coefficient α. This is an arc start method for consumable electrode gas shielded arc welding in which the coefficient α is finely adjusted with 0.5 as a center value so that the bead shape of the arc start portion becomes a desired shape.

  In the second invention, the initial feeding speed Fi [mm / s] of the welding wire during the initial time Ti and the steady feeding speed Fa [mm / s] of the welding wire after the initial time Ti has elapsed. The initial value Ti is set to the same value, and the initial time Ti is set to Ti = 10 · α / vw according to the coefficient α and the welding speed vw. Arc start of consumable electrode gas shielded arc welding according to the first invention Is the method.

  According to the first aspect of the invention, the welding condition changes by setting the initial time Ti until the welding torch starts moving after the arc start to the time until the initial welding amount Yi reaches the reference welding amount Yt. However, since the initial time Ti is automatically set to an appropriate value, the bead shape of the arc start portion can always be improved. Since the initial time Ti is automatically set according to the welding conditions, the time required for obtaining an appropriate value of the initial time Ti, which has been required in the past, is unnecessary, and the production efficiency is improved.

  According to the second invention, in addition to the above effect, when the initial feeding speed Fi and the steady feeding speed Fa are the same value, the initial time Ti is Ti = 10 · α depending on the coefficient α and the welding speed vw. It can be calculated as / vw. For this reason, since the circuit configuration for calculating the initial time Ti is simplified, the cost of the welding apparatus can be reduced.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a timing chart at the time of arc start according to the embodiment of the present invention. FIG. 4A shows the welding start signal St, FIG. 4B shows the feed control signal Fc, FIG. 4C shows the welding current Io, and FIG. 4D shows the movement permission signal Wcr. (E) shows the welding speed (moving speed of the welding torch) vw, and FIG. (F) shows the change over time of the initial welding amount Yi. This figure corresponds to FIG. 7 described above, and only the parts different from FIG. 7 will be described below.

In the figure, the operation up to time t2 is the same as that in FIG. At time t2, when the welding current Io is started as shown in FIG. 5B, the calculation of the initial welding amount Yi is started as shown in FIG. Here, assuming that the diameter d [mm] of the welding wire and the feed speed detection value Fd [mm / s], the initial welding amount Yi [mm ³ ] is expressed by the following equation.
Yi = ∫π · (d / 2) ² · Fd · dt (1) Therefore, the integration is started from time t2 and the initial welding amount Yi is calculated every moment. As shown in FIG. 5F, the initial time Ti [s] is terminated at time t3 when the initial welding amount Yi reaches the reference welding amount Yt. In response to this, movement of the welding torch is started as shown in FIG. 5E, and the feed control signal Fc is a value corresponding to the steady feed speed Fa as shown in FIG. To change.

The reference welding amount Yt is a value obtained by multiplying a steady welding amount Yc per 1 cm of welding length (hereinafter, simply referred to as a steady welding amount) by a coefficient α. That is, Yt = α · Yc. The steady welding amount Yc [mm ³ / mm] is calculated by the following equation using the welding wire diameter d [mm], steady feeding speed Fa [mm / s], and welding speed vw [mm / s].
Yc = 10 · π · (d / 2) ² · Fa / vw (2) In this equation, the diameter d, the steady feeding speed Fa, and the welding speed vw are welding conditions determined in advance before welding. The steady welding amount Yc is a predetermined value.

  FIG. 2 is a conceptual diagram of the bead shape of the arc start portion for explaining the coefficient α. In order to form a bead shape substantially the same as the steady welding amount Yc per 1 cm of the weld length at the arc start portion, the initial welding amount Yi = 0.5 · Yc may be used. Therefore, the coefficient α = 0.5. However, the bead shape of the arc start portion can be finely adjusted to a desired shape by finely adjusting the coefficient α. The fine adjustment width is about 0.5 ± 0.2.

Here, consider a case where the initial feeding speed Fi and the steady feeding speed Fa are the same value. Since the feed speed detection value Fd = Fi = Fa during the initial time Ti, the above equation (1) becomes the following equation.
Yi = π · (d / 2) ² · Fa · Ti
Since Yi = α · Yc is established when the initial time Ti elapses, the following equation is obtained by substituting the above equation and equation (2) into this.
Ti = 10 · α / vw (3) Therefore, when the initial feed speed Fi and the steady feed speed Fa are the same value, the appropriate initial time Ti can be calculated by the above formula (3). it can.

  FIG. 3 is a diagram in which an initial time Ti at which the bead shape of the arc start portion becomes a desired shape when the welding speed vw and the steady feeding speed Fa are changed is obtained by a test. This figure shows the case where the initial feed speed Fi and the steady feed speed Fa are the same value, a mild steel wire having a diameter of 1.2 mm is used as the welding wire, and the T-shaped fillet joint is welded with carbon dioxide arc. As shown in the figure, even when Fa = 8 m / min and Fa = 15 m / min, the initial time Ti can be approximated by a curve L1. The curve L1 can be expressed as Ti [s] = 10 · 0.5 / vw [mm / s]. Since this agrees with the above equation (3), the coefficient α = 0.5 is supported by the test.

  The welding apparatus for carrying out the arc start method according to the embodiment of the present invention is the same as that shown in FIG. However, the configuration of the welding power source 5 is the one shown in FIG. Hereinafter, each circuit will be described with reference to FIG.

  The power supply main circuit MC receives an AC commercial power supply (3-phase 200 V or the like) as input, performs output control such as inverter control according to a drive signal Dv described later, and outputs a welding voltage Vo and a welding current Io. The voltage setting circuit VS outputs a predetermined voltage setting signal Vs. The voltage detection circuit VD detects the welding voltage Vo and outputs a voltage detection signal Vd. The voltage error amplification circuit EV amplifies an error between the voltage setting signal Vs and the voltage detection signal Vd, and outputs a voltage error amplification signal Ev. This circuit forms constant voltage characteristics for consumable electrode gas shield arc welding. When an external welding start signal St is input, the drive circuit DV outputs a drive signal Dv for driving the inverter circuit of the power supply main circuit MC.

  The initial feed speed setting circuit FIS outputs a predetermined initial feed speed setting signal Fis. The steady feeding speed setting circuit FAS outputs a predetermined steady feeding speed setting signal Fas. The switching circuit SW switches to the a side when a later-described movement permission signal Wcr is at the Low level, and outputs the initial feeding speed setting signal Fis as the feeding speed setting signal Fs, and to the b side when it is at the High level. The above-mentioned steady feeding speed setting signal Fas is output as the feeding speed setting signal Fs. The feeding error amplification circuit EF amplifies an error between the feeding speed setting signal Fs and the feeding speed detection signal Fd from the feeding motor WM, and outputs a feeding error amplification signal Ef. When an external welding start signal St is input, the feed control circuit FC outputs a feed control signal Fc for controlling the feed motor WM according to the feed error amplification signal Ef.

  The reference welding amount calculation circuit YT receives the above-described steady feeding speed setting signal Fas, a predetermined wire diameter φd, a predetermined coefficient α, and an external welding speed setting signal vws as input, based on the above equation (2). And the reference welding amount signal Yt is output. The current detection circuit ID detects the welding current Io and outputs a current detection signal Id. The initial welding amount calculation circuit YI determines that current energization starts when the current detection signal Id is equal to or greater than the threshold value, starts the calculation of the above formula (1) with the feed speed detection signal Fd as an input, When the value reaches the value of the reference welding amount signal Yt, the movement permission signal Wcr is output (High level).

[effect]
FIG. 5 is a bead shape diagram of an arc start portion showing an example of the effect of the present invention. This figure corresponds to FIG. 9 described above. FIG. 4B shows the case where the welding speed is increased with the case of FIG. 4A as the reference welding condition, and FIG. 4C shows the case where the groove shape is widened and the steady feeding speed is increased. . In the present invention, the initial time Ti is automatically set to an appropriate value even if the welding conditions such as the welding speed and the steady feeding speed change, so that the bead shape of the arc start portion is always good as shown in FIG. become.

  The present invention can be applied to consumable electrode gas shielded arc welding of various metal materials such as aluminum, stainless steel and magnesium as well as steel. Further, the arithmetic processing of the initial time Ti may be performed by the robot control device. An automatic cart or the like can be used instead of the robot.

It is a timing chart of the arc start method of consumable electrode gas shield arc welding concerning an embodiment of the invention. It is a bead shape conceptual diagram showing the relation between initial welding amount Yi and steady welding amount Yc concerning an embodiment of the invention. It is a related figure of welding speed vw and steady feeding speed Fa, and initial time Ti concerning an embodiment of the invention. It is a block diagram of the welding power supply concerning the present invention. It is a bead shape figure of the arc start part which shows an example of the effect of the present invention. It is a block diagram of the conventional consumable electrode gas shield arc welding apparatus. It is a timing chart which shows the conventional arc start method. It is a figure which shows the bead shape of the conventional arc start part. It is a bead shape figure of an arc start part for explaining a subject.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Welding wire 2 Base material 2a Bead 2b of arc start part 3 Bead 3 of steady part 3 Arc 4 Welding torch 5 Welding power supply 6 Manipulator 7 Robot controller d Diameter DV Drive circuit Dv Drive signal EF Feed error amplifier circuit Ef Feed error amplifier Signal EV Voltage error amplification circuit Ev Voltage error amplification signal Fa Steady feed speed FAS Steady feed speed setting circuit Fas Steady feed speed setting signal FC Feed control circuit Fc Feed control signal Fd Feed speed detection (value / signal)
Fi initial feed speed FIS initial feed speed setting circuit Fis initial feed speed setting signal Fs feed speed setting signal ID current detection circuit Id current detection signal Io welding current L1 curve MC power supply main circuit Mc operation control signal St welding start signal SW switching circuit Ti initial time VD voltage detection circuit Vd voltage detection signal Vo welding voltage VS voltage setting circuit Vs voltage setting signal vw welding feed rate vws welding speed setting signal Wcr movement permission signal WM feed motor Yc steady welding amount YI initial welding amount Arithmetic circuit Yi Initial welding amount YT Reference welding amount arithmetic circuit Yt Reference welding amount Yt Reference welding amount signal α Coefficient

Claims (2)

Arc start of consumable electrode gas shielded arc welding in which welding current starts energizing at the time of arc start and starts moving the welding torch at a predetermined welding speed vw [mm / s] after the initial time Ti [s] has elapsed. In the method
The initial time Ti is set to a time until the initial welding amount of the welding wire from the time when the welding current starts energization reaches a reference value obtained by multiplying the steady welding amount per 1 cm of the welding length by a coefficient α, An arc start method for consumable electrode gas shielded arc welding, wherein the coefficient α is finely adjusted with 0.5 as a center value so that the bead shape of the arc start portion becomes a desired shape. The initial feeding speed Fi [mm / s] of the welding wire during the initial time Ti and the steady feeding speed Fa [mm / s] of the welding wire after the initial time Ti elapses are set to the same value, and the initial value is set. 2. The arc start method for consumable electrode gas shielded arc welding according to claim 1, wherein the time Ti is set to Ti = 10 · α / vw by the coefficient α and the welding speed vw.

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