JPS5814061Y2 - Shield device for sewing and welding work part of electric resistance welded pipes - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a shield device used when sewing and welding electric resistance welded pipes in an atmosphere of inert gas or reducing gas.

When welding an electric resistance welded tube, if the material of the electric resistance welded tube is a high manganese material or a high chromium additive material, inclusions called penetrators tend to remain in the welded portion, which significantly deteriorates the quality of the welded portion.

The cause of the penetrator is the oxygen 02 in the atmosphere and the manganese Mn in the material while heating the ERW tube with high frequency current.
When chromium, Cr, etc. float to form oxides, which are applied with a squib and a 7-tube set,
This is thought to be because it remains in the molten core without being discharged outside.

One of the measures to prevent this occurrence is to perform welding in an atmosphere of inert gas or reducing gas.

Conventionally, when sewing and welding ERW pipes in an atmosphere of inert gas or reducing gas, for pipes with large outer diameters, -L gas Z was sprayed directly onto the welded part, or when the edge of the ERW pipe was welded. Only the heating part has been locally covered with a shield box, and for pipes with a small outer diameter, the welding equipment has also been covered with a shield box, but conventional shielding equipment However, there was a drawback that it was not possible to determine the extent to which shielding was being performed.

For example, if pipe forming conditions such as mill speed change, the shielding condition will also change, and it will also be greatly affected by the pressure and flow rate of the shielding gas.

In this way, with the conventional welding method, it was not possible to determine the degree of shielding, so welding could not be performed with confidence, leading to variations in quality.

The present invention was developed in view of the above-mentioned circumstances, and its purpose is to make it possible to determine the degree of shielding by incorporating an oxygen analysis mechanism, so that even if the tube manufacturing conditions change, the pressure and flow rate of the shielding gas The suture of ERW pipes can be easily tracked by adjusting the angle, making it easier to manage the welding of ERW pipes made of materials such as high manganese materials and high chromium additive materials, which are particularly susceptible to penetrator formation. The present invention aims to provide a shielding device for a welding work section.

Hereinafter, the present invention will be explained based on an embodiment shown in the drawings.

The drawings show an example in which the shielding device of the present invention is incorporated into a welding device for sewing and welding electric resistance welding pipes by high-frequency resistance welding.

To explain the outline of this welding device, 1 is an electric resistance welding pipe, 2.2
3 is a squeeze roll for forming the ERW pipe 1 into a circular pipe and welding it, 3 is a contact tip, and squeeze roll 2
, 2, in the process of forming the ERW tube 1 into a circular tube and welding it, a high frequency current is passed directly to the welded part of the ERW tube 1 from the contact tip 3 to generate heat due to the contact resistance of the welded part, and the squeeze roll 2, Pressure is applied in step 2 to stitch and weld the electric resistance welding tube edges 1a, 1a.

By this welding, a suture welding section 4 is formed in which the electric resistance welding tube edges 1a, 1a are opened in a V-shape from the welded portion 1b toward the unwelded portion 1C.

Hereinafter, the shield device of the present invention related to this suture welding work section 4 will be explained.

Reference numeral 5 in the figure indicates a shielding gas ejection mechanism, and this shielding gas ejection mechanism 5 is arranged to face the inner and outer surfaces 1d and le of the ERW tube 1, and is designed to cover the suture welding section 4 of the ERW tube 1. The outer shield box 7.8 consists of a plurality of chambers in which the shield gas 6 is ejected and the pressure of the ejected shield gas 6 can be adjusted as described below.
It is equipped with.

The inner shield box 7 is moved from a position corresponding to the welding input point (position of the contact tip 3) to a squeeze roll 2,
2 to 1 on the inner surface 1d of the ERW tube 1 over the position corresponding to 2.
Four independent and integrated chambers 7a, 7b, 7C, and 7d installed at a distance of about Qmm are sequentially provided from the input to the output side of the electric resistance welded tube 1, and the chambers 7a and 7b are equipped with electric A large number of gas ejection holes 9a are formed facing the inner surface 1d of the sewn tube 1.
. . , 9b . Gas outlet 9C
. . . , 9d . . . are provided at predetermined intervals vertically and horizontally.

In addition, the outer shield box 8 is connected to the squeeze rolls 2, 2 from the vicinity of the welding input point (position of the contact tip 3).
2 to l on the outer surface 1e of the ERW tube 1 over a position slightly past
Three independent and integrated chambers 8a, 8b, and 8C installed at a distance of about Qml'11 are sequentially provided from the inlet side to the outlet side of the ERW tube 1. A number of gas ejection holes 10a are formed facing the outer surface 1e of the pipe 1.
. . , 10b . A large number of gas ejection holes 10C are provided vertically and horizontally at predetermined intervals.

And each chamber 7a, 7b, 7c, 7d
, 8a, 8b, and sc are equipped with gas supply pipes 11 for injecting inert gas or reducing gas used as shield gas 6, and the flow rates and pressures of these gases are automatically controlled. The gas ejection holes 9a... can be adjusted arbitrarily or manually.
, 9b..., 9c..., 9d...
..., 10a..., 10b...

By ejecting the gas from the 10 C..., the heating portions and the welding portions 1b of the electric resistance welded tube edges 1a, 1a are shielded.

Reference numerals 12 and 13 in the figure indicate inner and outer support mechanisms that support the inner and outer shield boxes 7.8 so as to be movable toward and away from the inner and outer surfaces 1d and le of the electric resistance welded tube 1.

As shown in FIG. 3, the inner shield box 7 is attached to and supported by an inner support mechanism 12 on a mandrel rod 14 for cutting the inner bead of the electric resistance welded tube 1.

That is, this inner support mechanism 12 includes a piston-cylinder mechanism 15 that connects the cylinder 15b to the mandrel rod 14 and connects the piston 15a to the member 16 and is driven by pneumatic or hydraulic pressure. The members 18 are connected via the turnbuckle 17, and both members 16, 18 are connected to the connecting rod 20 through the compressed coil spring 19.
..., and the guide rollers 21 provided at both ends of the member 18 are brought into rolling contact with the inner surface 1d of the ERW tube 1, and the distance between the inner shield box 7 and the inner surface 1D of the ERW tube 1 is a turn. The distance between the members 16, 18 is adjusted by the buckle 17, and the distance between the members 16, 18 is adjusted by nuts 22 threaded onto both ends of the connecting rod 20, which protrude from the members 16, 18. .

The outer support mechanism 13 also includes a screw cylinder mechanism 23 driven by pneumatic or hydraulic pressure, which has a piston 23 a connected to an outer shield box 8 and a cylinder 23 b attached to and supported by a frame 24 of a welding device. Be prepared.

Further, reference numeral 25 in the figure is an oxygen analysis mechanism that samples gas in the suture welding work section 4 covered with the shielding gas 6 and analyzes the oxygen content of this gas.

That is, this oxygen analysis mechanism 25 has a gas sampling port 26.
a to the ERW pipe edge L in the suture welding work section 4 of the ERW pipe 1.
Gas sampling pipes 2 facing near the heating parts a and la
6.26, which is equipped with a gas sampling device 27 that samples gas through the gas sampling device 26, and which automatically and continuously analyzes the amount of oxygen contained in the gas sampled with this gas sampling device 27 and displays the results. It is equipped with an automatic quantitative analyzer 28.

The operation of the device configured as described above will be explained.

First, when the material of the ERW pipe 1 enters in the direction of arrow A shown in the figure, the inner shield box 7 is moved by the shortening operation of the piston-cylinder mechanism 15 in order to prevent damage to the shield device by the front end of the material. The outer shield box 8 is lowered downward, and the outer shield box 8 is pulled upward by the shortening operation of the screw cylinder mechanism 23.

When the material of the ERW tube 1 enters the squeeze roll 2.2, the piston-cylinder mechanism 15.23 is extended to separate the inner and outer shield boxes 7.8.
be installed in the designated position.

In this state, the valve of the shielding gas cylinder (not shown) is opened, and the inert gas or reducing gas used as the shielding gas 6 is passed through the pipe 11.
Respective chambers 7a, 7b of outer shield box 7.8
, 7C, 7d, 8a, 8b, 8C1: The injected gas is injected into each gas ejection hole 9a, 9b, 9C.
, 9d, 10a, 10b, and are ejected from the IOC to shield the heated portion and welded portion 1b of the ERW pipe edges 1a, 1a.

Next, the suture welding section 4 of the electric resistance welding pipe 1 is removed using the gas sampling device 27.
After checking the shield condition by analyzing the oxygen content of the sampled gas with an oxygen content automatic analyzer 28, stitching and welding of the electric resistance welded pipe 1 is started.

During welding, the oxygen content analyzer 28 automatically and continuously measures the shielding condition, and if the shielding condition changes due to fluctuations in pipe manufacturing conditions, etc., the pressure and flow rate of the shielding gas 6 should be adjusted. If the amount of oxygen in the suture welding work section 4 is controlled automatically or manually to an appropriate value (according to experiments by the inventors, the amount of oxygen is 0.1 to 0.6%), Control so that suture welding of electric resistance welded pipes made of materials containing high manganese or high chromium can be performed satisfactorily.

Immediately after welding is completed and the rear end of the ERW pipe 1 exits the shield device, the piston-cylinder mechanisms 15 and 23 are each shortened again to prevent damage to the shield device at the rear end of the ERW pipe 1. It prevents it.

After confirming the operation of this piston-cylinder mechanism 15.23, close the valve of the shield gas cylinder.

Incidentally, the relationship between the shield box and the ejection pressure of the shield gas is as shown in FIGS. 4 I and II, according to experiments conducted by the present inventors.

These Figures I and II are based on the upper shield box 8, and the pressure ratios of the ejected gas in the three chambers 8a, 8b, and 8C are the results of experiments under four conditions as shown in Figure 4II. It can be seen that when the pressure ratio of the ejected gas is set to 2:F2, the amount of oxygen in the seam welding work section 4 is most effectively shielded, as shown by the diagram in Figure 4.

Therefore, also in the shield device of the present invention, the electric resistance welded pipe 1
The person should be able to adjust the pressure of the ejected gas from the chambers 7a, 7C, 7d and 8a, 8c located on the outlet side so that it is greater than the pressure of the ejected gas from the central chambers 7b and 8b. be.

In addition, although the above-mentioned embodiment explained the case where it was implemented in high frequency resistance welding, the present invention can be implemented in the same way in the case of high frequency induction welding.

As explained above, the shielding device of the present invention is arranged to face the inner and outer surfaces of an ERW pipe, and ejects a shield gas to cover the suture welding portion of the ERW pipe, and the ejected shield gas A shield gas blowout mechanism is equipped with an inner and outer shield box consisting of multiple chambers that can adjust the pressure of each chamber, and the inner and outer shield boxes can be moved toward and away from the inner and outer surfaces of the ERW tube. and an oxygen analysis mechanism that collects gas in the suture welding work area covered with the shielding gas and analyzes the amount of oxygen in this gas. It is possible to determine the degree of shielding in the sewing and welding work area of ERW pipes, and even if pipe manufacturing conditions change, the pressure and flow rate of the shielding gas can be adjusted appropriately for each chamber of the inner and outer shield boxes, making it easy to do so. This has the effect of being able to follow the flow and shielding most effectively, resulting in the best suture welding.

Therefore, it is easy to manage the welding of electric resistance welded pipes made of materials such as high man index materials and high chromium additive materials, which are particularly susceptible to penetrator formation.

Furthermore, the positions of the inner and outer shield boxes can be adjusted by moving the inner and outer shield boxes toward and away from the inner and outer surfaces of the ERW tube using the inner and outer support mechanisms, thereby preventing damage to the device. .

[Brief explanation of the drawing]

1 to 3 show an embodiment of the present invention, in which FIG. 1 is a vertical side view, FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1, and FIG. A cross-sectional view taken along the line III-III, Figures I and II show the relationship between the shield box and the ejection pressure of the shielding gas, ■ is a diagram showing the experimental results, and II is an explanatory diagram of the experimental conditions. be. 1... ERW pipe, 1a... ERW pipe edge, 1b... Welded part, 1C...
Unwelded part, 1d... Inner surface of the ERW tube, 1e...
...Outer surface of the ERW pipe, 2...Squeeze roll, 3...Contact tip, 4...Sewing welding section of the ERW pipe, 5... ...Shield gas ejection mechanism, 6...Shield gas, 7...
Inner shield box, 8...Outer shield box, 9a, 9b, 9c, 9d, 10a, 10b
, 10 C... Gas outlet, 11...
・Gas supply pipe, 12...Inner support mechanism, 13.
...Outer support mechanism, 14... Mandrel rod for cutting inner bead, 15°23... Piston-cylinder mechanism, 17... Turnbuckle, 19.・・・・・・Coil spring in compressed state, 2
0... Connecting rod, 22... Nut, 24
... Frame of welding equipment, 25 ... Oxygen analysis mechanism, 26 ... Gas sampling pipe, 26 a.
...Gas sampling port, 27...Gas sampling device,
28...Oxygen amount automatic analyzer, A......Entry direction of the ERW tube.

Claims (1)

[Scope of utility model registration request] A plurality of chambers are disposed facing the inner and outer surfaces of the ERW pipe and eject shielding gas to cover the sewing and welding portion of the ERW pipe, and the pressure of the ejected shielding gas can be adjusted respectively. A shield gas ejection mechanism including an outer shield box, an inner and outer support mechanism that supports the inner and outer shield boxes so as to be movable toward and away from the inner and outer surfaces of the ERW pipe, and the shield gas 1. A shield device for a seam welding work part of an electric resistance welding pipe, comprising an oxygen analysis mechanism for collecting gas in the seam welding work part covered with water and analyzing the amount of oxygen in the gas.