JPS5933071B2 - Welded part sealing device for ERW pipes - Google Patents

Description

[Detailed description of the invention] The present invention relates to welding of ERW pipes during manufacture of ERW pipes.

The present invention relates to a welding part sealing device that adjusts the atmosphere of the welding part by sealing the vicinity of the welding part. ERW pipes are made by forming a band-shaped coil into a tubular body using a large number of rolls, then heating the edge portion to a predetermined temperature by induction heating with a work coil or direct current heating with a contact tip, and then processing with welding rolls. Manufactured by pressure welding.

With this method, the steel pipe at the input part can be manufactured without any defects, but steel containing components such as Cr, which easily generates oxides and has a high melting point of oxides, may be oxidized when welded in an oxidizing atmosphere. The drawback was that particles remained in the welded area, which could easily cause welding defects. Therefore, various inert gas sealing methods have been proposed as a countermeasure against this problem. According to the research conducted by the present inventors, the requirements for a sealing device for a welded part are (1) a structure that completely isolates the heated part from air and water;

Also, although it varies depending on welding conditions and materials to be welded, it is desirable that the O2 concentration is 0.2% or less and the dew point is 0°C or less. (2)
Shape suitable for tight spaces between welding rolls and contact tips or work coils.

(3) The structure should be free from adhesion of scale and dirt.

(4) Durable enough to withstand long-term use (5o(
5) The structure must allow for visible welding points and heated edges.

However, there is no conventional weld sealing device that satisfies all of these conditions.

The purpose of the present invention is to provide an extremely practical welded part sealing device for an electric resistance welded pipe that satisfies all of the above-mentioned conditions. In a sewing pipe welding device, a front seal and a rear seal are provided at the front and rear of the isoheater or mandrel in close contact with the inner surface of the tubular body, and a an inner seal consisting of an intermediate seal provided on the in-heater with the front part in close contact with the left and right sides of the tubular body with the front part being in close contact with the left and right sides of the tubular body with an appropriate interval, and the front seal; and a suction seal that is in close contact with the outer surface of the tubular body at the upper part of the front part of the intermediate seal, and an inert gas inlet at the upper part of the work coil or contact chip. This is a welded portion sealing device for an electric resistance welded pipe, characterized in that it has an outer seal having a shape with a reduced cross-sectional area.

Next, the configuration of the apparatus of the present invention will be described based on the drawings, taking as an example the case where heating is performed using a work coil.

FIG. 1 is a perspective view showing one embodiment of the weld sealing device of the present invention, FIG. 2 is a longitudinal sectional view of the weld seal device shown in FIG. 1, and FIG. 3 is a weld seal shown in FIG. 1. FIG. 2 is a cross-sectional view of the device. In the figure, the inner seal 21 is in close contact with the inner surface of the tubular body 1, and the front seal 8 is fixed to the front part of the in-heater 7. A rear seal 11 fixed to the rear part of the tubular body 10, and an appropriate interval 11, 12 between the front seal 8 and the rear seal 11, respectively, so that the front part is in close contact with the upper part and the left and right sides of the tubular body 1, The parts other than the front part are in close contact with the left and right sides of the tubular body 1 and consist of an intermediate part seal 9 fixed to an in-heater 7. Reference numeral 14 denotes a suction section seal, and as shown in FIG. 2, this suction section seal 14 is provided in close contact with the outer surface of the tubular body 1 above the front section seal 8 and the intermediate section seal 9.

6 is an outer seal.As shown in the figure, this outer seal 6 has an inert gas inlet 28 in the upper side wall 17, 17'.
, 28/, and surrounds the upper part of the work coil 5 and the welding point 15, from the upper part to the lower part so that the cross-sectional area of the part through which the inert gas flows (indicated by the dashed arrow) gradually decreases. As shown in FIG. 3, its cross section has a V-shape so that its cross-sectional area decreases, and its rear part is located on the heated edge 1' and the welding point 15. The welding rolls 4, 4' are provided in close contact with each other with a space having a height of .

Next, the apparatus of the present invention will be explained in detail with reference to the embodiments shown in FIGS. 1 to 3.

The outer seal 6 mainly covers the ceiling plate 18, side walls 17, 17/
, a front wall 16} and a rear wall 19. The outer seal 6 is
It is supported by a frame 26 fixed to the side walls 17, 17' and the front wall 16. Frame 26 is fixed to roll housing 24 with bolts 27. The rear wall 19 has a nose portion 30 for the purpose of sealing the roll housing 24 side and for guiding inert gas in the direction of the welding point 15. The nose portion 30 is inserted between the welding rolls 4, 4'. This nose part 30 is closest to the edge part 1' and the upper part of the welding point 15, but it is still several times? }V, there is no need to worry about scale, dirt, etc. adhering. Gas blowing pipes 20, 20' are fixed above the side walls 17, 177, and inert gas is blown into the outer seal 6 from the blowing ports 28, 281. 91J walls 17, 17' are fixed to the rear of the walls 17, 17' with retaining plates 23, 23, which are in direct contact with the outside of the welding rolls 4, 4', and are used to seal inert gas and to seal the welding rolls 4, 4'. Cooling water is prevented from entering into the outer seal 6.

As a result, the resistance welding rolls 4, 4' can also be used as part of the seal side wall, and there is no need to provide anything special near the narrow welding area. Additionally, the welding rolls 4, 4' are cooled by applying soluble oil from the nozzles 29, 29'.

The holding plates 23, 23' are made of a non-metallic elastic body, such as neoprene sponge or rubber, and the welding rolls 4,
It is designed to accommodate the left and right movements of 4'. Further, work coil seals 22, 22 for sealing the work coil 5 are provided below the side walls 17, 17'. The work coil seals 22, 22' have elongated holes 31 to enable movement of the work coil 5 in the tube axis direction, and are slidable in the tube axis direction.
Fixed by The front wall 16 and the rear wall 19 are provided almost vertically, but the shapes of the welding rolls 4 and 4' are such that the cross section of the side walls 1r and 1T outer seal 6 decreases from the top to the bottom. Accordingly, it is formed in a V-shape. This structure makes it easy to maintain the pressure of the inert gas inside the outer seal 6 when inert gas is blown into the upper part of the outer seal 6, and even if there are some gaps between the welding rolls 4, 4' and the tubular body 1, the air can be This has the advantage that there is no entrainment. In fact, in the example described later, the gap is 2 to 3 m7!
It has been confirmed that there is no problem even if L is open. As for the material of the outer seal 6, a non-metallic material is preferable since the part near the work coil 5 receives induction heating, and as mentioned above, acrylic or PVC is used so that the internal state can be seen from the viewpoint of workability. It is desirable that the material be transparent. A special glass window 25 is also provided in the front wall 16 so that the interior of the outer seal 6 can be observed. If such an external seal is used, the pressure in all parts of the seal will be higher than the external surface, so there will be no entrainment of air, and the flow of inert gas will be shown by the dashed arrows in Figures 2 and 3. This is the ideal flow. In addition, the structure of the seal is simple, and there is a space just above the heated edge, so there is little dirt attached to the seal, and there is no risk of dirt getting caught in the welding part. Also, the consumable part of the outer seal 6 is the presser plate 23 that is in contact with the welding rolls 4, 4/.
, 23', it is sufficiently durable9, and also has the advantage that the seal can be easily attached and detached, and the work can be completed in an extremely short time. Next, the prevention of intrusion of cooling water and the like and the removal of moisture will be explained.

The water-soluble soluble oil flowing inside the tubular body 1 during tube forming is removed by an inner seal 6 provided inside the tubular body 1.
is dammed by a front seal 8.

The overflow of the soluble oil, the soluble oil adhering to the edge portion V, and other dirt are removed by suction from the suction port 13 by a suction device (not shown). In-heater 7
is fixed to the mandrel 10, and an inner bead cutter (not shown) is connected to the rear of the mandrel 10.

The in-heater 7 has a ferrite core inside a non-metallic cylindrical body made of epoxy or Teflon, and this ferrite core is cooled by soluble oil sent through the inside of the mandrel 10. The cooled soluble oil is discharged from a hole 12 provided in the mandrel 10 and cools a subsequent inner bead cutter (not shown). The soluble oil released into this pipe is almost completely dammed up by the rear seal 11 of the inner seal 6. Some soluble oil flowing from the front seal 8} and the rear seal 11 of the inner seal 6 flows into the inert gas flow path shown in the figure (indicated by the broken line arrow).
Accordingly, it is sucked together with inert gas from the suction port 13 by a suction device (not shown). Middle seal 9 of inner seal 6
The internal space of the tubular body 1 is divided into an upper part and a lower part as shown in Fig. 2b [X-X sectional view in Fig. 2a], and the flow of inert gas is indicated by the broken line arrow in Fig. 2. It has a flowing structure. Examples of the present invention will be described below. Although the present invention has been explained above by taking the case of high frequency induction welding as an example, the present invention can also be used for high frequency resistance welding using a contact tip as described above.

Examples thereof are shown in FIG. 4 and FIG. 5. In this embodiment, welding is performed using two welding rolls. The edge portion 60 of the tubular body 41 is heated by direct current heating from the contact chips 44, 44', and is pressed into contact with the welding rolls 40, 40' at a welding point 62 to form the tube 42. The inner seal 65 provided on the inner surface of the tube is exactly the same as in the previous embodiment, and consists of a front seal 49, an intermediate seal 50, and a rear seal 51 provided on the in-heater 46. 45
is a mandrel, and the cooling water of the in-heater 46 is discharged from the hole 48.

In this case, if an in-heater is not used, the structure may be such that the mandrel is provided with the above-mentioned inner seal.

Sorible oil, steam, etc. inside the pipe are removed from the suction port 63 by a suction device (not shown). The outer seal 47 is attached to the front wall 55;
It consists of a ceiling plate 54, a rear wall 53} and side walls 56 and 57,
They are constructed with good airtightness.

The rear wall 53 is provided with a nose portion 64 as shown in FIG. 4 for the same purpose as in the previous embodiment. Side walls 56, 57
As in the previous embodiment, there is an inert gas blowing pipe 5 at the top.
8,58//> are provided so that inert gas is blown into the outer seal 47 from the inlet ports 59,597, and when viewed in the tube axis direction (Fig. 5), it has a V-shape. Since the structure is configured such that the cross-sectional area through which the inert gas flows becomes smaller toward the lower part, air inflow from the outside where the pressure is high is eliminated. In addition, the attachment and detachment of the seal is easy and can be completed in a very short time, as in the previous embodiment, and the flow of inert gas is directed to the heated edge 60 and the welding area as shown by the broken line arrow in the figure. The flow is such that the point 62 is completely sealed. In addition, the side wall 5
7 is provided with good airtightness to the power feeding arm 43. Since the present invention is a welding part sealing device as described above, it can completely seal the heated part in the manufacture of electric resistance welded pipes, and has a shape suitable for narrow spaces near the welding part. It is possible to obtain an electric resistance welded steel pipe with excellent quality of the welded part because it has less adhesion of scale, dirt, etc., can withstand long-term use, and the condition near the welded part can be monitored from the outside.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing one embodiment of the weld sealing device of the present invention, Fig. 2 a is a longitudinal sectional view of the weld seal device shown in Fig. 1, and Fig. 2 b is Fig. 2 Af) -X sectional view, FIG. 3 is a cross-sectional view of the weld sealing device shown in FIG. 1, and FIG. 4 is a longitudinal sectional view showing another embodiment of the weld sealing device of the present invention.
FIG. 5 is a sectional view taken along the line AA in FIG. 4. In the figure, 1, 41... tubular body, V, 6O.
...Edge part, 3, 3', 4, 4', 40, 40
'... Welding roll, 5... Work coil, 6, 47... Outer seal, 7, 46...
...In-heater, 8,49...Front seal,
9,50...middle seal, 10,45...
...Mandrel, 11.5 volumes...Rear seal,
14, 52... Suction part seal, 15, 62...
...Welding point, 21,65...Inner seal,
28, 28', 59, 59t...Inlet, 44,
44t...Contact chip.

Claims (1)

[Claims] 1. In an electric resistance welding pipe welding device that welds the edges of a continuously running tubular body while heating, a front seal and a rear seal are provided in close contact with the inner surface of the tubular body at the front and rear parts of an impeder or mandrel. The front part is provided in the impeder in close contact with the upper part and the left and right sides of the tubular body, and the parts other than the front part are provided in close contact with the left and right sides of the tubular body, with appropriate spacing in the front and rear between the seal, the front seal, and the rear seal. an inner seal consisting of a middle part seal, a suction part seal in close contact with the outer surface of the tubular body at the upper part of the front part of the front seal and the middle part seal, and an inert gas inlet at the upper part of the work coil or the middle part seal. 1. A welded portion sealing device for an electric resistance welded pipe, comprising a contact tip and an outer seal that surrounds a welding point and has a cross-sectional area that decreases from the top to the bottom.