JPS5832034B2 - Vertical welding method for curved surfaces, etc. - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention is a method for welding a curved surface whose inclination angle changes as welding progresses while maintaining the penetration amount, base material light, and back penetration ratio constant. This invention relates to a vertical welding method.

In general, vertical welding is performed using automatic electrogas welding equipment, etc., but in both cases, a welding cart is attached to the base material so that it can be moved upward by resting on the groove, and a welding torch attached to the welding cart is opened. The welding wire is inserted through the welding torch into the welding area and continuously connected to the welding area surrounded by the welding metal.

By the way, a welding torch is usually mounted on a welding cart so that its mounting angle can be adjusted, but in actual welding, for example, when welding a vertical surface or an inclined surface with a constant inclination angle, the mounting angle must be adjusted to a fixed angle. It is normal to maintain the

In addition, the welding heat input, which is determined by arc current, arc voltage, wire protrusion length, etc., is also generally maintained constant.

When welding a vertical surface or an inclined surface with a constant inclination angle, good welding results can be expected by maintaining the welding torch installation angle and welding heat input constant. However, if the angle of inclination changes as welding progresses, good welding results cannot be obtained.

In other words, when welding a curved surface using the conventional vertical welding method described above, the amount of penetration and the penetration ratio on the front and back sides of the base metal are uniform over the entire weld length, and a bead with a constant width is formed. There was a problem that I couldn't do it.

This invention was made to solve this problem, and even when the inclination angle changes as welding progresses, such as on a curved surface, the amount of penetration and the front and back sides of the base material can be maintained regardless of the change in the inclination angle. The present invention aims to provide a vertical welding method for curved surfaces, etc., which can maintain a uniform penetration ratio and form a bead of constant quality over the entire weld length.

Now, as shown in FIGS. 1 and 2, the base material inclination angle θ is θ1.
Considering the case where θ2 (G1 minus G2) is different, the welding wheel moves upward while resting on the base material, so that it inclines approximately in line with the inclination of the base material.

Therefore, when the attachment angle of the welding torch to the welding wheel is maintained constant, the inclination angle of the welding torch with respect to the base material is a constant angle α regardless of the inclination angle of the base material.

is maintained.

Therefore, the inclination angle θ1. According to θ2, the wire aiming angle with respect to the molten pool surface is G1°G2 (G1>G2
) changes.

Further, even if the thickness d of the base material is constant, the effective thickness changes from Dl to D2 (Dl>D2) depending on the inclination angle of the base material.

Therefore, the surface area of the molten pool changes depending on the inclination angle of the base metal, so if the welding heat input is kept constant, the heat input per unit surface area changes as the inclination angle changes, and therefore the amount of penetration increases. It is thought that this will change.

In addition, since the wire aiming angle changes depending on the inclination angle of the base metal, this causes a difference in the amount of molten metal flowing toward the back side of the base material in the molten pool due to the arc force, resulting in a penetration ratio between the back side and the front side. changes.

Therefore, in vertical welding of curved surfaces, etc., the above problem can be solved by keeping the wire aiming angle with respect to the molten metal surface of the molten pool constant and the heat input per unit area of the molten metal surface constant.

Therefore, according to Fig. 3, the curved surface part of the base material is
Let us consider the case where only the welding is performed.

In this case, the plate thickness of the base metal is d1, the groove shape is a ■ shape, the gap is the inclination angle of the G1 welded part is θ, and the arc voltage Va is
, the arc electric current fiIa is constant, and the amount of metal deposited per unit time is expressed in volume as m1, and the required welding time is Δt.

Then, the volume V1 of the groove space to be filled with molten metal during welding is given by the following equation (1) since the minute distance Δl can be approximated as a straight line.

Further, the volume ■2 of the molten metal transferred from the welding wire into the groove when Δ is the time is given by the following equation (2).

holds true.

Further, the welding heat input Q given to the base metal in time Δ is given by the following, where η is the efficiency.

Furthermore, the following relationship holds between the plate thickness d of the base material and the effective plate thickness.

Therefore, from equations (3), (4), and (5) above, the heat input amount q per unit area of the molten pool is as follows.

In this equation (6), since ■a, Ia, η, and △l are always constant even if θ changes, the above equation (6) can be expressed as follows.

By the way, the amount m of metal deposited per unit time is proportional to the wire melting speed, and the wire melting speed is proportional to the wire protrusion length Le.
Assuming that x is proportional to zo, the following relationship holds true.

Therefore, if the relationship between the inclination angle θ and the wire protrusion length Lex is established, (s), (9),
From equation (10), the following relationship holds true.

Therefore, given that, becomes.

By the way, the practical range of inclination angle of the base metal to be welded is 4
Since it is 5° to 90°, it can be approximated as follows, and the amount of heat input q per unit area of the hot water surface can always be kept approximately constant regardless of the inclination angle θ of the base metal.

On the other hand, in the above relational expression, if the following relationship is established, the heat input q per unit area of the hot water surface will change according to the change in the inclination angle θ of the base metal, as in the case above.
can be kept approximately constant regardless of the inclination angle θ of the base material.

On the other hand, the wire aiming angle α relative to the surface of the molten pool is determined by the attachment angle α of the welding torch with respect to the welding cart depending on the change in the inclination angle θ of the base metal.

can be held constant regardless of the inclination angle θ.

This invention has been made based on such research results, and the mounting angle α of the welding torch with respect to the welding cart is determined according to the inclination angle θ at the welded portion of the base metal.

The wire aiming angle α with respect to the molten pool surface is always kept constant by changing the angle θ, and the amount of metal deposited per unit time m is changed according to the change in the above-mentioned inclination angle θ, and the arc voltage Va is also changed. The heat input amount q per unit area of the molten metal surface of the molten pool is always kept constant.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.

The curved surface portion of the base material 1 (the curved surface portion is shown as a simple inclined plate in the figure).

), a welding cart 3 is attached to the groove 2 of the base material 1 so that it can move upward.

The welding truck 3 has a front truck 4 disposed on the front side of the base material 1, and a back truck 5 facing the back side of the base material 1, that is, on the concave curved surface side.

Both carts 3 and 4 are pressed onto the base material 1 by a pressure mechanism 6.

The pressure mechanism 6 has a threaded end passing through the front cart 4, a rear end passing through the groove 2, and a connecting frame 8 which is pivotally attached to the back cart 5 by a pin 7, and a threaded end of the connecting frame 8. It consists of a screwed nut 9 and a pressure spring 10 inserted between the nut 9 and the table carriage 4.

The front truck 4 has guide rollers 11 with a large diameter at its upper and lower ends to fit into the groove 2 at its center, and the back truck 5 has guide rollers 12 at its upper and lower ends. have

The front and rear trucks 4 and 5 forming the welding truck 3 each have support arms 13 and 14 extending downward from their lower ends and resting on the base material 1.

These support arms 13 and 14 are connected to the front and back carriages 4, respectively.
, 5 so as to be rotatable in one direction of the base material.
Further, it is elastically biased in one direction of the base material by a spring member (not shown).

The support arms 13 and 14 each have a groove 2 in the base material 1 at the lower end.
The water-cooling pads 16 and 17 are held in sliding contact with the front and back surfaces of the welded portion, surround the welded portion, prevent molten metal from flowing down from the groove 2, and form a molten pool 15.

Although not shown in detail in the figure, the water cooling pads 16 and 17 are rotatably supported by support arms 13 and 14 along the curved surface of the base material 1, and are also supported by spring members (not shown). It is adapted to be pressed against the base material 1.

By the way, the support arm 13 provided on the front side of the base material 1 has a molten pool 15, and preferably one end of the rotating arm 20 is attached to a portion adjacent to the arc point 1B generated above the molten pool 15 by means of a fulcrum pin 19. It is pivoted so that it can rotate freely.

The position of this fulcrum pin 19 is determined so that the rotation of the rotation arm 20, especially the protrusion length Lex of the protruding contact wire, is proportional to the inclination angle θ at the welded part of the base metal 1. There is.

The body of an electric cylinder 21 is rotatably attached to the center of the rotating arm 20 by means of a fulcrum pin 22.

The electric cylinder 21 has a telescopic rod 23 whose distal end is rotatably connected to the upper end of the support arm 13 by a fulcrum pin 24 .

Then, the body of the wire feeding motor 25 is attached to the other end of the rotating arm 20 with its output shaft side facing toward the base material 1.

A frame 26 is attached to the output shaft side of the motor 25, and a base end portion of a welding torch 27 is attached to the frame 26.

This welding torch 27 has its tip extending into the groove 2 of the base material 1.

The tip of the welding torch 27 is curved downward to guide the fed welding wire W to the center of the molten pool 15.

The frame 26 is provided with a wire feeding mechanism 28 that continuously feeds the welding wire W to the welding torch 27.

This wire feeding mechanism 28 is provided with an outlet 29 at the base end of the welding torch 27 and an inlet 30 at the termination side.
A feed roller 31 driven by a motor 25 and a pressure roller 32 for pressing the welding wire W onto the roller 31 are provided between the feed roller 31 and the feed roller 31 .

A gyro device 33 is installed on the upper surface of the body of the wire feeding morph 25 as a device for detecting the inclination angle of the welded portion of the base material 1, which is used for attitude control in, for example, aircraft.

This gyro device 33 detects the inclination angle A of its own central axis S with respect to the vertical axis vl, and outputs an electric signal, for example, a voltage Ea, proportional to the inclination angle A.

By the way, the inclined posture of this gyro device 33 is caused by the telescopic rod 23 of the electric cylinder 21 connecting between the fulcrum pins 22 and 24.
In other words, since the support arm 13 is provided approximately parallel to the base material 13, it is determined by the inclination angle θ of the base material 1 relative to the horizontal axis hl. .

On the other hand, the wire aiming angle α with respect to the molten metal surface of the molten pool 15 is
Since the welding torch 27 is integrated with the gyro device 33, it depends on the inclination angle of the gyro device 33.

Therefore, in order to keep the wire aiming angle α at a predetermined constant angle, it is sufficient to keep the inclination angle A of the gyro device 33 constant, so the inclination angle N of the gyro device 33
(This angle is determined by setting the wire aiming angle.)

) is set, the reference voltage Es is compared with the output voltage Ea of the gyro device 33, and the difference voltage is set as a control signal so that the difference becomes zero. As electric cylinder 21 telescopic rod 23
The length of the extension is controlled.

In other words, controlling the extension length of the telescopic rod 23 of the electric cylinder 21 so that the inclination angle A of the gyro device 33 is constant means that the welding torch The mounting angle α of No. 27 with respect to the welding cart 3.

By changing the angle .alpha., the wire aiming angle .alpha. relative to the molten metal surface of the molten pool 15 is always kept constant.

Further, the tip of the welding torch 27 and the welding torch 2
Strictly speaking, the fulcrum pin 19 that supports the welding torch 27 and the arc point 18 have a special positional relationship. Mounting angle α with respect to the trolley 3.

When the length of the wire W is changed, the protrusion length Lex
and the inclination angle θ at the welded part of the base metal 1 as expressed by the above-mentioned equation (10), that is, Lex=
They are mutually arranged in a positional relationship such that a relationship of 3·θ holds true.

However, with such a configuration, even if the inclination angle θ of the welded part of the base metal 1 changes as welding progresses, the gyro device 33 detects this and changes the telescopic rod 23 of the electric cylinder 21. Activate the welding trolley 3 of the welding torch 27
installation angle α.

is controlled so that the wire aiming angle α with respect to the molten metal surface of the molten pool 15 is always kept constant.

Therefore, regardless of the change in the inclination angle of the base material 1, the base material 1
The effect is that the penetration ratio between the front and back surfaces can be made uniform.

Moreover, the tip of the welding torch 27 and the welding torch 27
The fulcrum pin 19 supporting the fulcrum pin 19 and the arc point 18 are in a special positional relationship, that is, the attachment angle α0 of the welding torch 27 with respect to the welding cart 3 is set so that the wire aiming angle α with respect to the molten metal surface of the molten pool 15 is always constant. are mutually arranged in a positional relationship such that the relationship Lex = k3・θ (k3 is a constant) holds between the protruding length Lex of the wire W and the inclination angle θ of the welded part of the base metal 1 when changing the Therefore, the above-mentioned Sita No. (10) (11) (12) (13)
Equation (14) As is clear, the amount of heat input q per unit area of the hot water surface can always be kept at a substantially constant value regardless of the inclination angle θ at the welded portion of the base metal 1.

In other words, even if the surface area of the molten pool 15 changes according to the inclination angle θ, the welding heat input Q changes accordingly, and the heat input q per unit area of the molten pool surface always remains approximately constant. be done.

Therefore, there is no problem that the bead width changes depending on the change in the inclination angle θ, and it is possible to form a bead with a constant width over the entire welding length.

In addition, FIG. 5 shows the change tendency of the bead width on the front and back sides of the base metal with respect to the change in the inclination angle θ of the base metal in the above embodiment, and the mounting angle α of the conventional welding torch.

In this figure, the change in the front bead width according to the above embodiment is shown by the actual line IB-1, the change in the back bead width is shown by the solid line B-2, and the change in the front bead width by the conventional device is shown in comparison with the one without adjustment. The change in the back bead width is indicated by the dotted line b -
Shown as 2.

As is clear from this figure, the mounting angle α of the welding torch is the same as in the previous embodiment.

When the wire aiming angle α is kept constant, the penetration ratio on the front and back sides of the base material is kept constant, and the bead widths on the front and back sides are also kept substantially constant.

Furthermore, FIG. 6 shows trends in changes in the effective plate thickness of the base material and changes in the welding speed V with respect to changes in the inclination angle θ of the base material in the above embodiment.

What should be noted in this figure is that the welding speed V changes as the inclination angle θ of the base metal changes, in other words, as the effective plate thickness changes. This is because the wire protrusion length Lex changes proportionally, indicating that the heat input amount q per unit area of the molten metal surface of the molten pool is kept constant.

In the experimental examples shown in FIGS. 5 and 6, the thickness of the base material 1 was 15 mm, the radius of curvature was 1800 R, and the groove interval was 15 mm.
±1 mm, welding voltage 36■ (constant), welding current 6
0OA (constant), protrusion length Lex of wire W is 20
This was carried out under extremely difficult conditions.

In the above embodiment, the welding torch 27 is rotated about the fulcrum pin 19, in other words, the angle at which the welding torch 27 is attached to the welding cart 3 is adjusted to keep the wire aiming angle constant, thereby simultaneously ejecting the wire. The most desirable method was to be able to adjust the length so that the heat input remained constant, but for example, in the case of a mechanism that fixed the length of the wire protrusion, it was necessary to adjust the angle at which the welding torch was attached to the welding cart. The arc voltage Va is changed by using a switching element such as a cyrisk, a transistor, etc. according to the change in the inclination angle θ.
Of course, it is also possible to provide a control function that is automatically set to satisfy the relationship θ to keep the heat input q per unit area of the hot water surface constant.

[Brief explanation of the drawing]

1 and 2 are schematic diagrams for explaining a conventional welding method, FIG. 3 is a schematic diagram for explaining the present invention, and FIG. 4 is a side view of an apparatus for explaining an embodiment of the present invention. figure,
FIGS. 5 and 6 are percentage lubrication line tables showing the effects of the same practical example. 1... Base material, 2... Bevel, 3...
...Welding cart, 15... Molten pool, 16,17.
...Cash, 18...Arc point, 20...
...Rotating arm, 21...Electric cylinder,
25...Wire feed motor, 27...
Welding torch, 28...Wire feeding mechanism, 33.
...Gyro device, W...Welding wire.

Claims (1)

[Claims] 1. The mounting angle α of the welding torch with respect to the welding cart according to the change in the inclination angle θ at the welded portion of the base metal. The wire aiming angle α with respect to the molten pool surface is always kept constant by changing the molten pool, and (a) the wire protrusion length Lex is adjusted in proportion to the inclination angle θ according to the change in the above-mentioned inclination angle θ. (b) The arc voltage V
A curved surface, etc., characterized in that the heat input amount q per unit area of the molten pool surface is always kept constant by changing a in inverse proportion to the inclination angle θ and keeping the wire protrusion length Lex constant. Vertical welding method. 2. The wire protrusion length Lex is the attachment angle α of the welding torch with respect to the welding cart. 2. A vertical welding method for curved surfaces, etc., according to claim 1, characterized in that the vertical welding method for curved surfaces, etc. changes when . 3. A vertical welding method for curved surfaces, etc., according to claim 1, characterized in that a change in the inclination angle θ of the welded portion of the base metal is detected by a gyro device attached to a welding cart. 4. The mounting angle α of the welding torch with respect to the welding cart is determined based on the detection result of the gyro device. The vertical welding method for curved surfaces, etc. according to claim 3, characterized in that the welding heat input amount Q is automatically controlled.