JPS6010784Y2 - Welding machine for overlaying tank bottom corners - Google Patents

Description

[Detailed description of the invention] This invention relates to a tank bottom corner welding machine that performs overlay welding on the bottom corner of a cylindrical tank. This was devised for the purpose of providing a welding machine that can automatically apply good build-up welding to the corner portions of tank bottoms.

Conventionally, as shown in Fig. 1, the corners of a large cylindrical tank 1 are formed by placing annular foundation blocks 3 with the same diameter as the tank's outer diameter on the foundation ground 2 on which the tank is to be installed, as shown in Fig. 2. The annular annular plate 4 is buried so that its upper surface is on the same horizontal plane as the upper surface of the foundation ground 2, and then an annular annular plate 4 is installed on top of the foundation block 3 and the foundation ground 2 inside it. The tank side plate 5 of the first stage of the tank 1 is placed above the center of the width of the foundation block 3 on the plate 4,
The tank side plate 5 and the annular plate 4 are joined by fillet welding 6 on both sides, and the tank bottom plate 7, which is laid on the foundation ground 2, is welded to the inner peripheral edge of the annular plate 4. The bottom is made liquid-tight.

The main cause of liquid leakage accidents that occur in large tanks formed to prevent liquid leakage in this way is that the shape of the fillet weld 6 generally has a large rising angle α.
It is thought that this is because the curvature ρ is small, and in addition to the hydraulic pressure of the liquid content, uneven settlement of the foundation ground 2 causes an overload external force to be applied to the tank body, causing large stress to occur in the fillet weld, causing damage. .

As a result of research conducted by the inventors of the present invention, it was found that the mechanism of generation of this excessive stress is as follows.

That is, when the liquid is poured into the tank 1 formed as shown in FIG. 2, a horizontal liquid pressure a is applied to the bottom tank side plate 5 as shown in FIG. 3, causing the annular plate 4 and the tank bottom plate to 7 is applied with vertical hydraulic pressure.

In response to this hydraulic pressure a, the tank side plate 5 attempts to horizontally move outward to the position indicated by the chain line in FIG. Since this is not possible, the upper part of the side plate 5 is rotated outward as shown in FIG.

Therefore, a horizontal force Q is generated inside the lower end C as a reaction force.

At this time, the annular plate 4 tries to follow the rotation of the base of the tank side plate 5, but the annular plate 4 inside the tank is prevented from rotating by the hydraulic pressure, so as shown in FIG. A large bending moment M occurs at the weld 6.

Furthermore, the extra length 8 of the annular plate 4 outside the tank
As shown in FIG. 5, the foundation block 3 receives a reaction force P that prevents the rotation, and the bending moment M is increased by the hydraulic pressures a and b.

Due to the bending moment M thus generated, a large local stress close to the yield stress of the base material is generated at the toe 9 of the inner fillet weld 6.

Therefore, there is a risk of damage due to repeated loads due to the inflow and outflow of the liquid content, overload external force due to unequal conditions, etc.

Through experiments by the present inventors, for example, a thickness of 30 to 50 rIr.
! ! In the large tank 1 in which an annular plate 4 having a thickness of 12 to 22 mm is fillet welded to the L tank side plate 5,
The angle θ between the tank side plate 5 and the annular plate 4 is 1~
For a repeated load of about 2 degrees, the number of repetitions is close to 200 depending on the shape of the fillet weld 6, and if the angle θ is 5 to 6 degrees, cracks may occur in the toe 9 at an early stage. understood.

This is because the fillet weld 6 generally has a large rising angle α at the toe, tends to have a small curvature ρ, and is also subject to hardening, softening, and embrittlement of the material due to the effects of welding heat.

Therefore, if excessive deformation occurs due to repeated loads due to the inflow and outflow of the liquid content, uneven subsidence of the ground, earthquakes, etc., as described above, there is a risk of large-scale damage to the toe.

In order to prevent this danger, the present inventors conducted research and found that the joint between the fillet weld 6 and the overlay weld, and the overlay toe, are located adjacent to the inside of the fillet weld 6, as shown in FIGS. 6 and 7. Good results can be obtained by performing overlay welding 10 in which the portion 10a is smooth and has a low excess buildup.

That is, the overlay welding 10 can disperse stress concentration occurring at the toe 9 and prevent cracking near the toe, thereby increasing the fatigue strength near the fillet weld on the inside of the tank between the tank side plate 5 and the annular plate 4. It has been found that it is possible to increase the bending deformability, that is, the angle θ until cracking occurs, and to reliably prevent the contents of a large tank from leaking.

In addition, in this overlay welding 10, rather than weaving a welding torch (described later) parallel to the tank side plate 5, weave the welding torch (described later) in a substantially perpendicular direction toward the tank side plate 5 as shown in the locus 11 and 12 shown in FIGS. It was found that overlay welding was superior in terms of strength.

The present invention provides a welding machine that performs this overlay welding.

Embodiments of the present invention shown in FIG. 10 and subsequent figures will be described below.

The welding machine of the present invention has a structure in which a self-propelled device 14, a side plate profiling roller 15, a reciprocating device 16, a control device 17, an operating device 46, a wire feeding device 19 for welding material, a wire reel 18, etc. are attached to a frame 13. It is designed to automatically perform overlay welding.

Next, the details and operation of each component will be explained.

The pedestal 13 has three frames, namely a first frame 13
It is structured in an H-shape by a, second frame 13b, and third frame 13c.

The reason why the frame 13 is made H-shaped is that the frame structure is relatively simple and requires only a small number of components, and as described later, the first and second frames 13a and 13b are connected to the third frame 13c. This is because the four drive rollers 21 and the four driven rollers 20 can be rotated independently of each other via the hinges H provided in the annular plates, so that the four driving rollers 21 and the driven rollers 20 can be prevented from separating from the annular plate at all times.

Each frame 13 is connected in a manner that can be assembled and disassembled using bolts and nuts, for example, as shown in FIGS. (Fig. 2) so that it can be brought in and assembled inside the tank.

Further, the pedestal 13 has first and second frames 13a and 13b removably connected to both ends of the third (7) 7L/- frame 13c, and a second frame 13b of the third frame 13c.
The axis of the third frame 13c (this axis becomes a horizontal axis perpendicular to the direction of movement of the welding machine when the welding machine is used) is attached to the end side where the welding machine is connected.

) is assembled into an H-shape by providing a rotatable hinge H around the frame 13a, the frame 13a having the drive roller 21 attached to both ends, and the frame 13b having the driven rollers 20 attached to both ends, as a third frame. 13c can be rotated separately about the axis of the annular plate 13c, and the above-mentioned 4.
It is supported by ring rollers and runs stably.

The self-propelled device 14 carries the welding machine body and runs the welding machine on the annular plate 4 parallel to the tank side plate 5 in the direction of the thick arrow in Fig. roller 20. two drive rollers 21,
The shaft S and the drive motor 22 with M speed gear should be avoided.

Each roller uses heat-resistant synthetic comb tires.

As shown in FIGS. 11 and 15, the output shaft of the drive motor 22 and the central axes of the two drive rollers 21 are connected to a worm 23 fixed to a shaft S connected to the output shaft, and a center axis of the two drive rollers 21. It is connected via a worm gear 24 that is coaxially connected and meshes with the worm 23.

By tilting the drive roller 21 toward the tank side plate 5 with respect to the running direction as shown by the dotted line in FIG. 11, a running speed toward the tank side plate 5 is generated, and the welding machine body is actively moved along the tank side plate 5. You can do it like this.

In order to tilt the drive roller 21, as shown in FIGS. 15 and 16, a circular hole 26 is formed in the upper surface 25a of the inner box 25 in which the drive roller 21 is built and the drive motor 22 is attached, and one hole is formed around the hole 26. A circular arc hole 26a is bored in the inner box 25.
is configured to be tightened to the stand frame 13a by bolts 45 and 45 inserted through the two holes, and the inner box 25 is rotated about a vertical axis around the circular hole 26 to tilt the drive roller 21. .

Therefore, even for a tank in which the annular plate 4 is inclined toward the inside of the tank, the welding machine main body can suitably follow the tank side plate.

As shown in FIGS. 11 and 12, the side plate tracing roller 15 is rotatably supported in all directions on a wheel frame 27 fixed to the end face of the mount 13 facing the tank side plate 5. The welding machine body is moved along the tank side plate 5 while coming into contact with the inner peripheral surface.

The reciprocating device 16 reciprocates in a horizontal plane substantially perpendicular to the running direction of the welding machine main body, and is used to weave the welding torch 40 fixed thereto.

As shown in FIGS. 10 to 12 and 17, a traveling rail 28 is fixed to the upper surface of the frame 13b perpendicular to the traveling direction of the welding machine main body, and a carriage 30 is attached to the rail 28 by a guide roller. 29.29, and the carriage 30 is reciprocated by a carriage drive roller 34 which is attached to the carriage 30 and rotates in forward and reverse directions.

As shown in FIG. 11.17, the traveling distance of the carriage 30, that is, the weaving width, is adjusted by the carriage 30 drive motor 3.
A normal reversing device such as a limit switch 43 for reversing the movement of the moving rail 28 is provided at the front and rear of the traveling rail 28.

Therefore, this reciprocating device 16 reciprocates through a constant weaving width by the forward and reverse rotation of the motor 34 during welding.

The wire feeding device 19 feeds a wire-shaped welding material 38 supplied from a wire reel 18 provided on a support 37 mounted on a pedestal 13a at an appropriate speed by a wire feeding roller 41 driven by a wire feeding motor 42. This is a device that supplies it into the welding torch 40 and performs overlay welding.

This torch 40 is attached to the frame 13 on the opposite side to the direction of welding progress.
By arranging the welding torch 40 as close as possible to the driven roller 20 (b), the welding torch 40 and the welding surface of the annular plate 4 are always kept at a constant distance from each other despite the ups and downs of the annular plate 4, and a stable arc phenomenon can be obtained.

The control device 17 causes the self-propelled device 14, the reciprocating device 16, and the wire feeding device 19 to operate in conjunction with each other to set welding conditions,
Automatically controls weaving trajectory settings, etc.

The control device 17 includes a time switch, a numerical controller, and the like.

The operating device 46 is an operating panel on which a welder sets various welding conditions when performing overlay welding.

Since the welding machine of the present invention is constructed and operates as described above, 1. It is possible to automatically perform overlay welding by weaving in a direction approximately perpendicular to the tank side plate while self-propelled along the tank side plate. .

2. Compared to manual welding, it is more efficient and can produce smooth and homogeneous welding with a peal shape free of harmful defects.

Therefore, the bending deformability of the inner corner of the tank can be significantly improved, and a tank without leakage accidents can be provided.

3 Welding conditions and weaving methods can be easily set by operating each device in a related manner.

4. It has a wide range of uses because it can be carried into an existing tank and stable overlay welding can be performed even on tanks with irregularly contoured annular plates.

[Brief explanation of drawings]

Figure 1 is a front view of a large cylindrical tank, Figure 2 is an enlarged sectional view taken along line A-A in Figure 1, and Figures 3 to 5 show the deformation process of the tank corner due to the hydraulic pressure of the liquid in the tank. Figure 6 is a partial vertical sectional view of the corner of the tank with overlay welding, Figure 7 is a plan view of Figure 6, and Figures 8 and 9 are planes similar to Figure 7 showing the weaving method. Figures 10 to 17 show an embodiment of the welding machine of the present invention, where Figure 10 is a front view, Figure 11 is a plan view, Figure 12 is a right side view, and Figure 13 is B of Figure 11. -B
14 is an enlarged sectional view of section H in FIG. 11, FIG. 15 is an enlarged sectional view taken along line CC in FIG. 11, and FIG.
5, and FIG. 17 is an enlarged front view of the left part of FIG. 10. 5... Tank side plate, 13... Frame, 1
4... Self-propelled device, 15... Side plate tracing roller, 16... Reciprocating device, 17...
・Control device, 19...Wire feeding device, 40・
...Welding torch, 46...Operating device.

Claims (1)

[Scope of utility model registration request] First frame 13a with drive rollers 21 attached to both ends
and a second frame 1 with driven rollers 20 attached at both ends.
3b to both ends of the third frame 13c in a disassembly manner, and around a horizontal axis perpendicular to the direction of movement, on the end side of the third frame 13c to which the second frame 13b is connected. A rotatable hinge H is provided to configure the pedestal 13 into an H-shape, and the pedestal 13 has a side plate tracing roller 15 that rotates in all directions, and power is transmitted to a drive roller 21 to move the side plate tracing roller 15 into a tank. A self-propelled device 14 is provided that allows the welding machine main body to run parallel to the tank side plate 5 while being in contact with the inner surface of the side plate 5, and a reciprocating device 16 is provided in a direction substantially perpendicular to the self-propelled direction of the welding machine main body. A welding torch 40 attached to the device 16 facing downward is combined with a wire feeding device 19 which is a welding material, and a control device 17 for operating the above-mentioned devices in conjunction with each other and an operating device 46 for setting welding conditions are provided. A welding machine for overlaying the bottom corners of tanks.