JP2002059264A - Gas shielded non-consumable electrode type metal arc welding equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas shielded non-consumable electrode type metal arc welding equipment capable of automatically and appropriately controlling the distance between a filler metal and a work. SOLUTION: This gas shielded non-consumable electrode type metal arc welding equipment comprises a welding torch 34 directed to grooves 16 of works 12 and 14, a wire nozzle 36 which is disposed adjacent to the welding torch 34 and feeds a wire W as a filler metal into the arc formed by the welding torch 34, wire nozzle moving devices 26, 28 and 32 for relatively moving the wire nozzle 36 to the works 12 and 14, and a power source 40 for supplying the power between the wire W and the works 12 and 14 to heat the wire W. The position of the wire nozzle 36 to the works 12 and 14 is controlled based on the deviation of the wire heating current.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a gas shield non-consumable electrode type arc welding apparatus.

[0002]

2. Description of the Related Art A gas shield non-consumable electrode type arc welding method represented by TIG welding has been conventionally known.
Gas shield non-consumable electrode type arc welding method, for example, TIG
In welding, an arc is generated between a tungsten electrode and an object to be welded in an inert gas atmosphere, and the heat is used to melt the object to be welded and a filler material (welding rod or wire) to perform welding. .

[0003]

In general, a filler material is inserted manually or automatically into an arc. However, in order to perform a gas shield non-consumable electrode type arc welding well, a filler metal in an arc is required. The distance between the material and the workpiece must be maintained properly. Conventionally, the distance between the filler material and the workpiece has been adjusted by hand to maintain a good welding state visually by a welding operator, resulting in reduced work efficiency and reduced weld quality. Had a problem.

An object of the present invention is to solve the problems of the prior art, and a gas shield non-consumable electrode system in which the distance between a filler material and a workpiece can be automatically and appropriately controlled. An object of the present invention is to provide an arc welding apparatus.

[0005]

A welding torch directed to a groove of an object to be welded, and a wire as a filler material disposed adjacent to the welding torch is directed into an arc formed by the welding torch. A wire nozzle, a wire nozzle moving device that moves the wire nozzle relative to the workpiece, and power supply between the wire and the workpiece to heat the wire. An automatic gas shield non-consumable electrode type arc welding apparatus comprising: a power supply device that performs power supply between the wire and the workpiece; a current value deviation value or a time average value of electric power supplied between the wire and the workpiece; The position of the wire nozzle with respect to is controlled.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. In the first embodiment of the present invention, a gas shield non-consumable electrode type arc welding apparatus 10 (hereinafter, simply referred to as an automatic welding apparatus 10) includes:
The two cylindrical or columnar workpieces 12 and 14 arranged horizontally are welded while rotating at a groove 16 in a state where the workpieces 12 and 14 abut each other. In the embodiment of FIG. 1, the workpieces 12 and 14 are attached to the automatic welding apparatus 10 in a state where the workpieces 12 and 14 are temporarily fixed at the groove 16 before starting welding. One of the objects to be welded 12 is rotatably supported by a cradle 18 having a support roller 20, and the other one of the objects to be welded 1.
4 is gripped by the gripping device 22 supported by the positioning device 24. The positioning device 24 positions the workpiece 14 gripped by the gripping device 22 with respect to the workpiece 12 supported by the receiving table 18 such that the respective central axes coincide with each other. The gripping device 22 is a positioning device 2
The workpieces 12 and 14 are also rotated by the rotation of the gripping device 22.

[0007] A welding torch 34 is provided toward the groove 16 of the workpieces 12 and 14. The welding torch 34 is attached by the manipulator arm 26 so as to be relatively movable with respect to the workpieces 12 and 14 in three orthogonal directions. More specifically, the manipulator arm 26 has a slide shaft 30 parallel to the central axis of the workpieces 12 and 14, and a movable body 28 is attached movably along the slide shaft 30, and is attached to the movable body 28. Is the elevating table 32 for the workpiece 1
The welding torch 34 is mounted on the lifting table 32 so as to be vertically movable along the radial direction or vertical direction 2 and 14 (defined as the Z-axis direction in this specification).
A wire nozzle 36 is also attached to the lift 32, and a welding wire W is fed from the wire reel 38 to the wire nozzle 36. Manipulator arm 26,
The moving body 28 and the lift 32 constitute a wire nozzle moving device controlled by the automatic welding control device 50.

In order to heat the wire W, a power supply 40
As a result, a predetermined electric power is applied between the wire W and the workpieces 12 and 14. More specifically, the cathode of the power supply 40 is connected to the wire W by the cathode wire 42, and the anode of the power supply 40 is connected to the workpieces 12 and 14 by the anode wire 44. The cathode electric wire 42 is provided with a wire heating current / voltage detector 46 for measuring a current value and a voltage value of the electric power supplied to the wire W. Wire heating current / voltage detector 4
6 is connected to a microcomputer 48, and the microcomputer 48 is also connected to an automatic welding control device 50. The microcomputer 48 controls the automatic welding control device 50 and the power supply device 4 according to the stored program.
A control command is issued for 0. For example, as the welding process progresses, a filler material is deposited on the groove 16 and the distance between the tip of the wire W and the workpieces 12 and 14 gradually decreases, so that the welding of the wire nozzle 36 and the welding torch 34 is performed. The position with respect to the objects 12 and 14 must also be corrected, and since the size of the groove 16 also changes, the amount of the filler material to be deposited also changes, and therefore the power (voltage) supplied to the wire W must also be changed. No. These welding conditions are programmed in advance and stored in the microcomputer 48. The power supply to the welding torch 34 is as follows.
This can be performed by the power supply device 40 or a power supply device (not shown) independent of the power supply device 40.

The operation of the first embodiment of the present invention will be described below with reference to the flowcharts of FIGS. Figures 4 and 5
5 shows a subroutine for controlling the positioning of the wire nozzle 36 of the automatic welding device 10 in the Z-axis direction by the automatic welding control device 50. When the welding process is started, the welding operator visually observes the state of the arc to obtain the welding target 1 of the wire nozzle 36 in which optimal welding conditions can be obtained.
The position in the radial direction with respect to 2, 14, that is, the height of the wire nozzle 36 is determined. This height or position of the wire nozzle 36 is defined as an initial position.

Once the initial position has been determined, the control subroutine is
Is started, and the parameter i is set in step S10.
0 (zero), and in step S12,
Wiring is performed in a predetermined cycle by the ear heating current / voltage detector 46.
Measure and sample the current value applied to the
From the obtained current value, a microcomputer 48
Deviation value I of fluctuation of current value within fixed time_devIs calculated, and
In step S14, the deviation I_devBut in advance micro
Determination value I stored in computer 48 _disAnd ratio
Are compared. I_devIs I_disLess than (step
If Yes in S14), the subroutine
In step S22, the parameter i is reset to 0 (zero).
After that, the process returns to step S12.

If I _dev is equal to or greater than I _{dis in} step S14 (No in step S14), the parameter i is compared with a predetermined number n, for example 10, stored in the microcomputer 48 in step S16. . If the parameter i is smaller than n (No in step S16), the subroutine proceeds to step S18, and the microcomputer 48 sends a predetermined value ΔZ _d to the automatic welding control device 50, for example, 1 mm.
, A command is issued to move the wire nozzle 36 downward along the Z-axis. Next, the subroutine adds 1 to the parameter i in step S20 and proceeds to step S20.
Return to 12.

If i is greater than or equal to n in step S16 (Yes in step S16), the subroutine proceeds to step S24, where the parameter i is reset to 0 (zero). Then, in step S26, the microcomputer 48 Then, a command is issued to the automatic welding control device 50 to move the wire nozzle 36 upward along the Z-axis by ΔZ _d × n, that is, to move the wire nozzle 36 to the first position where the wire nozzle 36 has started to be lowered by the above subroutine. Further, in step S28, a command is issued to the automatic welding control device 50 to move the wire nozzle 36 upward along the Z axis by a predetermined value ΔZ _u , for example, 0.5 mm.

Next, in step S30, the wire
Deviation value I of fluctuation of current value applied to W_devIs calculated
In step S32, the deviation I_devIs judged
Value I _disIs compared to I_devIs I_disPlace smaller than
If (Yes in step S32), the subroutine
In step S34, the parameter i is set to 0 (zero).
After returning to step S12, the process returns to step S12.

If I _dev is greater than I _{dis in} step S32 (No in step S32), the parameter i is compared with a predetermined value m, for example, 5 stored in the microcomputer 48 in step S36. . If the parameter i is smaller than m (No in Step S36), 1 is added to the parameter i in Step S38, and the process returns to Step S28. If the parameter i is greater than or equal to m (Ye in step S36)
s), the subroutine proceeds to step S40, and the microcomputer 48
A warning is issued for 0, and a command is issued to return the wire nozzle 36 to the initial position where the wire nozzle 36 began to be lowered by the above subroutine.

Next, the effects of the present embodiment will be described with reference to FIG. FIG. 6 shows the automatic welding apparatus 10 shown in FIGS.
Of the average value (shown by a solid line) of the wire heating current and the deviation value of the wire heating current (shown by a dashed line (Indicated by). When the tip position of the wire W is in the range shown by Z _a, the deviation of the wire heating current good welding has been performed less than 1A. When the tip position of the wire W approaches the workpieces 12 and 14 (the tip position of the wire shifts to the left in the graph of FIG. 6), the electric resistance in the arc decreases, and the wire heating current increases. . When the wire tip position is too close to the workpieces 12 and 14 and deviates from the proper range Za, the deviation value of the wire heating current is 1 _A.
Increase beyond. The tip end of the wire W is the workpiece 1
When the wire is separated from 2, 14, the electric resistance in the arc increases, so that the wire heating current decreases. Then, the wire tip position deviates from the appropriate range Z _a too away from the weld object 12, deviation of the wire heating current increases beyond 1A. Further, when the position of the tip of the wire separates from the workpiece, a so-called wire droplet state occurs, the melting of the filler material in the arc becomes discontinuous, and the deviation value of the wire heating current becomes extremely large.

The welding operator by visually observing the welding state from experience during welding start, the wire tip position is adjusted manually the position of the wire nozzle 36 to enter a proper range Z _a. By the way, even if the welding operator adjusts the wire tip position to the optimum position at the start of welding, as the welding process proceeds, for example, the feeding speed of the wire W from the wire reel 38 and the welding at the groove 16 are increased. Due to a mismatch with the deposition rate of the material,
The position of the wire tip relative to 2, 14 also changes,
If the feeding speed of the wire W is relatively low, the relative position of the wire tip shifts to the right, and if the feeding speed of the wire W is relatively high, the relative position of the wire tip shifts to the left.

[0017] Conventionally, a welding operator uses a wire during the welding process.
By adjusting the position of the nozzle 36 manually,
This shift of the wire tip position is compensated. Against this
In this embodiment, the wire tip is automatically
Position is in proper range Z_aIs controlled to be maintained within
You. For example, the initial position Z₀Is in the proper range Z_aAlso inside
However, the tip of the wire W is to be welded during the welding process.
It is too close to the objects 12, 14 and the proper range Z in FIG.
_aDeviating from Z₁Considering the case of shifting to
The determination in step S14 of the flowchart in FIG.
And the wire nozzle 36 is directed toward the workpieces 12 and 14.
approach. Wire nozzle 36 contacts workpieces 12 and 14
When approaching, the wire tip position in FIG. 6 shifts to the left
The deviation of the wire heating current gradually increases.
Until i reaches a predetermined number n, for example, 10, step S
Steps S20 to S20 are repeated. i is a predetermined number n
Is reached, i is reset to 0 (zero) (step S24).
After that, in step S26, the wire nozzle 36 is
Move the wire tip to the initial Z position.₁Return to
You. Next, in step S28, the wire nozzle 3
6 is a predetermined distance Z_uTo move the wire
The end position is separated upward from the workpieces 12 and 14. Wa
Deviation I of ear heating current_devIs the judgment value I_disSmaller than
By repeating this until it becomes a proper value
Wire tip position is in proper range Z₀Return to. Predetermined number m
When the wire nozzle 36 is moved upward,
Flow deviation I _devIf the value is not the appropriate value,
When it is judged to be normal, an alarm is issued and the wire nozzle 36 is
First position Z₁To return to.

[0018] Conversely, those initial position Z ₀ were within proper range Z _a is, the tip of the wire W while the welding process progresses excessively away from the object to be welded 12 and 14, appropriate 6 Considering the case of shifting to the Z ₂ deviates from the scope Z _a, the determination in step S14 in the flowchart of FIG. 4 is No, wire nozzle 36 is welded object 12,1
Approaching towards 4. Step S12 to step S2
By repeating 0, the wire tip position becomes the proper range Z
Return to ₀ again. The predetermined number n is an appropriate value from experience, for example, 1
It can be set to 0.

In this embodiment, as described above, the control is performed so that the wire nozzle 36 is brought closer to the workpieces 12 and 14 first. As can be understood from FIG. 6, this is because the ends of the wires W are welded to the workpieces 12 and 14, especially
If the wire nozzle 36 is too far away from the wire 6, the wire may be in a molten state, and the welding process may not be able to be maintained.
14 is advantageous.

Next, a second embodiment of the present invention will be described with reference to FIGS. In the first embodiment, the position control of the wire nozzle in the Z-axis direction is mainly performed based on the deviation value of the wire heating current, that is, the change of the wire heating current value. However, in the second embodiment, the average of the wire heating current is averaged. Control is performed based on the value. Also in the second embodiment, when the welding process is started in the same manner as in the first embodiment, the welding operator visually observes the state of the arc and obtains the optimum welding conditions by the welding object of the wire nozzle 36. The position in the radial direction with respect to 12 and 14, that is, the height of the wire nozzle 36 is determined. When this initial position is determined, a control subroutine is started. In step S42, the current value and voltage value applied to the wire W in a predetermined cycle by the wire heating current / voltage detector 46 are measured and sampled.
The values are averaged by the microcomputer 48, and the current average value and the voltage average value at the initial position are set as a reference average current value I _aveR and a reference average voltage value E _aveR .

Next, in step S44, a deviation value _Idev of the fluctuation of the current value is calculated. In step S46, this deviation value I _dev is
8 is compared with the judgment value I _dis stored in the reference _numeral 8. This I _dis is generally a larger value than the I _dis of the first embodiment, and is a value corresponding to the molten state of the wire droplet on the right side of the graph of FIG. If I _dev is equal to or greater than I _dis (Yes in step S46), it is determined that the wire droplet is in a molten state. In step S48, the microcomputer 48 controls the automatic welding control device 50 to move the wire nozzle 36 to a predetermined position. A command is issued to forcibly move down by a distance ΔZ, for example, 2 mm, and the subroutine returns to step S42.

If I _dev is smaller than I _dis (No in step S46), the voltage value applied to the wire W in a predetermined cycle is measured and sampled by the wire heating current / voltage detector 46, and is measured by the microcomputer. The current average voltage value E _ave is obtained by averaging according to 48, and is compared with the reference average voltage value E _aveR in step S52. Reference average voltage value E _aveR and average voltage value E _ave
Is greater than or equal to the determination value E _dis (step S
If Yes in step 52), it is determined that the welding path has been changed, and the subroutine returns to step S42 to return to the reference average current value _IaveR and the reference average voltage value E again.
_Ask for _aveR .

Reference average voltage value E_aveRAnd average voltage value E_ave
If the absolute value of the difference from the
(No in step S52), wire heating current / voltage detection
Is applied to the wire W in a predetermined cycle by the heater 46
Measure the current value, sample it, and
The current average current value I_{av e}
, And in step S56, the reference average current value I_aveR
Is obtained. As already described with reference to FIG.
The tip position of the wire W approaches the workpieces 12 and 14
And the electric resistance in the arc decreases, so that the wire is heated.
Since the current increases, ΔI and the reference average current value I_aveRAnd
Compare the current wire tip to the initial position
The approximate location of the edge is expected. In step S58
The absolute value of ΔI is_dismIs compared to ΔI
The absolute value is the judgment value I_dismSmaller than (step S5
8 if Yes), the wire tip from the initial position
Proper range Z for small displacement and good welding_aInside
And the subroutine returns to step S44.
Return.

[0024] If the absolute value of ΔI is equal to or greater than the determination value I _dism (if at step S58 of No), the displacement of the position of the wire tip from the initial position deviates from the proper range Z _a which exerts a great good welding And step S6
At 0, ΔI is multiplied by a negative coefficient α to obtain ΔZ, and the wire nozzle 36 is moved by ΔZ (step S62).
At this time, when ΔZ is a negative number, the wire nozzle 36 is moved in a direction in which the wire tip approaches the workpieces 12 and 14, that is, downward in FIG. 3, and when ΔZ is a positive number In the direction in which the tip of the wire separates from the workpieces 12 and 14, that is, upward in FIG.
To move. As shown in FIG. 6, when the position of the tip of the wire approaches the workpieces 12 and 14, the electric resistance in the arc decreases, and the wire heating current increases.
The rate of increase is based on the fact that the rate of increase is approximately proportional to the distance between the tip of the wire and the workpieces 12 and 14. According to the present embodiment, by appropriately selecting the value of the coefficient α in advance by experiments or the like, it is possible to automatically and appropriately maintain the position of the wire tip with respect to the workpieces 12 and 14. Further, it is possible to detect a change in the welding path based on the average value of the voltage and appropriately cope with the change.

[Brief description of the drawings]

FIG. 1 is a schematic front view of an automatic welding apparatus according to a preferred embodiment of the present invention.

FIG. 2 is a schematic side view of the automatic welding apparatus according to the embodiment.

FIG. 3 is a diagram showing a positional relationship among a workpiece, a welding torch, a wire nozzle, and a wire.

FIG. 4 is a flowchart illustrating a wire tip position control subroutine according to the first embodiment.

FIG. 5 is a flowchart illustrating a wire tip position control subroutine according to the first embodiment.

FIG. 6 is a graph showing changes in a wire heating current average value and a wire heating current deviation value with respect to a wire tip position.

FIG. 7 is a flowchart illustrating a wire tip position control subroutine according to a second embodiment.

FIG. 8 is a flowchart illustrating a wire tip position control subroutine according to a second embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Gas shield non-consumable electrode type arc welding device (automatic welding device) 12 ... Workpiece 14 ... Workpiece 16 ... Groove 18 ... Cradle 22 ... Gripping device 24 ... Positioning device 26 ... Manipulator arm 28 ... Moving body 32 ... elevating table 34 ... welding torch 36 ... wire nozzle

Claims (4)

[Claims] 1. A welding torch directed to a groove of an object to be welded, and a wire disposed adjacent to the welding torch and supplying a wire as a filler material into an arc formed by the welding torch. Nozzle, a wire nozzle moving device that moves the wire nozzle relative to the workpiece,
An automatic gas shield non-consumable electrode type arc welding apparatus comprising: a power supply for supplying electric power between the wire and the workpiece to heat the wire; A gas shield non-consumable electrode type arc welding apparatus wherein a position of the wire nozzle with respect to the workpiece is controlled based on a deviation value of a current value of electric power supplied to the workpiece. 2. When the deviation value of the current value is larger than a predetermined judgment value, the wire nozzle is caused to approach the workpiece with a predetermined distance, and the deviation value of the current value is obtained again and compared with the judgment value. The deviation value comparison step is repeated, and if the deviation value of the current value does not become smaller than the determination value even after repeating the deviation value comparison step a predetermined number of times, the wire nozzle is returned to the initial position, and the wire is moved over a predetermined distance. The gas shield non-consumable electrode type arc welding apparatus according to claim 1, wherein the nozzle is separated from the workpiece. 3. A welding torch directed to a groove of an object to be welded, and a wire disposed adjacent to the welding torch and supplying a wire as a filler material into an arc formed by the welding torch. Nozzle, a wire nozzle moving device that moves the wire nozzle relative to the workpiece,
An automatic gas shield non-consumable electrode type arc welding apparatus comprising: a power supply for supplying electric power between the wire and the workpiece to heat the wire; A gas shield non-consumable electrode type arc welding apparatus wherein the position of the wire nozzle with respect to the workpiece is controlled based on a time average value of a current value of electric power supplied to the electrode. 4. The time average value of the current value in a good welding state is defined as a reference current average value, and the difference between the reference current average value and the current current time average value is larger than a predetermined determination value. The wire nozzle is moved with respect to the workpiece by a distance proportional to a difference between the reference current average value and a time average value of a current current value when the reference value is reached.
The gas-shielded non-consumable electrode-type arc welding apparatus according to 1.