JPS5912147Y2 - Electric resistance welded pipe manufacturing equipment - Google Patents

Description

[Detailed description of the invention] This invention relates to an improvement of a welded pipe manufacturing apparatus using electric resistance welding, and in particular to an electric resistance welded pipe manufacturing apparatus that can perform seam annealing without problems even when manufacturing small diameter pipes. .

Electric resistance welded pipes, also known as ERW pipes, utilize heat generated by electrical resistance to intensively heat both edges of a steel strip that is continuously fed and shaped into a roughly tubular shape by a group of forming rolls. , manufactured by butt welding both edges of the steel strip together using squeeze rolls.

The general manufacturing process for electric resistance welded pipes is explained using the flow diagram in Figure 1. There is an entry process (not shown) in which the coil is unwound and the edge of the steel strip is finished into a shape suitable for welding, and the steel strip 1 is passed through a large number of A forming process (2) in which the steel strip is continuously formed into a tubular shape using a group of rolls of a certain shape, a welding process (2) in which both edges of the steel strip 1 are butt welded by a welding machine 3 and a squeeze roll 4, and a seam ring process in which the heat-affected zone of the weld is heat treated. III. It consists of a diameter-setting step (not shown) in which the diameter is shaped into a perfect circle and straight using a diameter-sizing machine, a cutting step (not shown) in which the diameter is set to a fixed size, and the like.

In the welding process, one of a low frequency welding method, a high frequency induction method, and a high frequency resistance welding method is employed.

Whichever welding method is used, the seam part is affected by the welding heat that intensively heats the seam part, and the structure of the material becomes different from that of the base metal part, which is not preferable in terms of product quality assurance.

Therefore, conventionally, the seam portion has been subjected to a heat treatment called so-called seam annealing using a boss annealer configured with an induction heater or the like provided after the squeeze roll.

However, although this seam annealing is actually carried out when manufacturing pipes of JIS-SGP-8O A or higher, even if the outer diameter is 80A, the ratio of the wall thickness t and the outer diameter D is t/ At present, this is not carried out when manufacturing so-called small diameter pipes in which D is 10% or more, in other words, the inner diameter is about 7 Qm/m or less.

The reason is as explained below. In other words, in such electric resistance welded pipe manufacturing equipment, roll lubricant, cooling water, etc. used in large quantities in the forming process remain on the bottom of the pipe during the forming process, and remain in the pipe until the cutting process. Since the water is not discharged to the outside, the water remaining in the tube is heated by the heat of the heat treatment of the seam portion at the boss annealer position and boils.

However, as mentioned above, JIS-SGP-80
In the case of pipes with an outer diameter of A or more, or a pipe with an inner diameter of 7Qm/m or more, the cross-sectional area of the pipe is sufficiently large, so the thermal effect is small and the water retained in the pipe almost never boils. In addition, even if it boils, the water vapor pressure does not rise to the point where it spews out from the opening between the two steel strips upstream of the weld, but in the case of small-diameter pipes such as those mentioned above, the cross-sectional area of the pipe is Because of its small size, its thermal influence is large, causing much of the water remaining in the pipe to boil, and its water vapor pressure easily rises to the point where it spews out from the openings on both edges of the strip upstream of the weld, creating the so-called blowback phenomenon. This is because the water vapor, residual water in the pipe accompanying this water vapor, and welding flash cool the welded part or get caught in the welded part, resulting in frequent welding defects.

In view of the above-mentioned points, this idea was developed to manufacture electric resistance welded pipes that prevent the blowback phenomenon of water vapor caused by the boiling of water stored in the pipes, ensure good welding even for small diameter pipes, and allow seam annealing to be performed without problems. The purpose is to propose a device.

That is, this invention is an electric resistance welded pipe manufacturing apparatus that is equipped with a boss annealer at the rear stage of the squeeze roll, and includes a suction conduit that sucks and discharges water retained at the bottom of the pipe into the pipe between the squeeze roll and the boss annealer. This is an electric resistance welded pipe manufacturing apparatus that is equipped with a high-pressure fluid injection pipe that injects high-pressure fluid in the direction of movement of the pipe.

This invention will be explained in detail below based on the accompanying drawings.

FIG. 2 is a partially cutaway vertical cross-sectional view showing an embodiment of the manufacturing device of this invention, and the same figure shows a method using a bead removal device installed inside the tube to remove the inner bead that occurs at the seam. This figure shows a case in which the suction conduit and the high-pressure fluid injection pipe are provided.

In the same figure, the bead removing device 5 is inserted into the tube 2 so that its tip is located downstream of the squeeze roll 4 from the opening between both edges of the steel strip that is in the process of being formed in the forming process, and its base end is located downstream of the squeeze roll 4. The mandrel 5a has an L-shape (see Fig. 1) and is fixedly held on a roll stand (not shown), and a bead is provided on the upper surface of a mounting base 5b that is swingably attached to the tip of the mandrel 5a. A cutting tool 5C, and a pressing member 5d that is repeatedly struck by a rod 5e provided in a mandrel 5a that is stroke-operated by a drive source (not shown) outside the pipe 2 in order to bring the cutting tool 5C into contact with the bead with an appropriate pressure. , and by manipulating the stroke amount of the rod 5e, the pie relative to the bead is
It is provided so that the bead can be cut while maintaining the contact pressure of 5C at a predetermined value.

Like the mandrel 5a, the suction conduit 7 for suctioning and discharging retained water, etc. at the inner bottom of the tube 2, is inserted into the tube 2 from the openings on both edges of the steel band in the process of being formed, and its tip is placed downstream of the squeeze roll 4. The mandrel 5a is inserted so as to be located on the side thereof, and is attached using a plurality of supporting metal fittings along the outer surface of the lower part of the mandrel 5a.

The tip is bent to bring it closer to the bottom surface of the tube, and the tip opening is shaped into a wide opening that follows the curved surface of the tube, so that it faces the bottom surface of the tube with an appropriate distance, and the rear end is attached to a mandrel. It is led out of the tube 2 in the same way as the proximal end of the tube 5a, and is connected to a suction pump (not shown), thereby suctioning and discharging the residual water etc. that reaches the position of the boss annealer 6 as much as possible. It is provided.

The high-pressure fluid injection pipe 8 that injects high-pressure fluid in the direction of movement of the pipe is connected to the remandrel 5 from the base end of the mandrel 5a.
The mandrel 5a is inserted into the mandrel 5a, and the tip protrudes from the tip of the mandrel 5a without interfering with the operation of the mounting base 5b, the pressing member 5d, and the rod 5e, and the tip is located upstream of the boss annealer 6.

A nozzle 9 is attached to the tip of the pipe 2 to diffuse and spray high-pressure fluid over the entire inner cross-section of the tube 2, and a high-pressure fluid supply source (not shown) is connected to the rear end. It is installed to blow away the steam generated in the pipe in the direction of travel of the pipe.

As mentioned above, in the illustrated embodiment, the suction conduit 7 is provided along the outer surface of the mandrel 5a, and the high-pressure fluid injection tube 8 is provided through the mandrel 5a. 5a, and the high-pressure fluid injection tube 8 may be provided along the outer surface of the mandrel 5a, or both tubes may of course be provided along the outer surface of the mandrel 5a or through the inside thereof.

Furthermore, as the high-pressure fluid to be ejected from the high-pressure fluid injection pipe 8, water, air, steam, etc. may be used, but steam is most preferably used from the viewpoint of the purpose.

In other words, since water supercools the seam part rather than the inside of the pipe, it is inappropriate when implementing the seam norm, and air has a pressure of 5 to 7 kg/cm' or more, which is the normal factory air pressure, to blow back water vapor etc. in the direction of pipe movement. This is because it is necessary to provide a pressurizing device.

On the other hand, in the case of steam, the steam pressure used in normal factories is 5
This is because water vapor etc. blown back at a pressure of ~7 kg/cm' can be easily blown away in the direction of movement of the pipe, and there is no need to worry about overcooling of the seam portion.

In the manufacturing apparatus of this invention having the structure detailed above, when seam annealing the tube, the water retained at the bottom of the tube is sucked and discharged by the suction conduit on the upstream side reaching the bottom annealer position. The amount of retained water reaching the store kneeler position can be reduced as much as possible, and the amount of water vapor generated can be reduced, and this water vapor is blown away in the traveling direction of the pipe by the high-pressure fluid injected from the high-pressure fluid injection pipe. It is possible to reliably prevent the so-called blowback phenomenon in which water vapor generated at the kneeler position and residual water, flash, etc. accompanying this water vapor blow back to the welding part.

Therefore, even for small diameter pipes, seam annealing can be carried out without any problems without worrying about welding defects.

By the way, with the conventional manufacturing equipment and the manufacturing equipment of this invention, JIS-SGP-5O A (outer diameter 60.5 mm,
When seam annealing was carried out on the production line during the production of 3.8mm wall thickness, conventional production equipment was unable to perform seam annealing because the blowback phenomenon was extremely severe and no welding could be performed. In this case, no blowback phenomenon was observed, stable welding was performed, and seam annealing could be performed without any problems.

[Brief explanation of drawings]

FIG. 1 is a flowchart showing the manufacturing process of an electric resistance welded pipe, and FIG. 2 is a partially cutaway side view showing an embodiment of the electric resistance welded pipe manufacturing apparatus according to this invention. In the figure, 1... steel strip, 2... pipe, 3...
...Welding machine, 4...Squeeze roll, 5.
...Bead removal device, 5a...Mandrel, 5b...Mounting base, 5C...Bite, 5d...Press member, 5e... ...Rod, 6...Bost annealer 7...Suction conduit, 8...High pressure fluid injection pipe, 9...
·nozzle.

Claims (1)

[Scope of utility model registration request] This is an electric resistance welded pipe manufacturing device that is equipped with a boss annealer after the squeeze roll, and includes a suction conduit that suctions and discharges retained water on the bottom of the tube in the tube between the squeeze roll and the boss annealer, and a tube that moves forward. An electric resistance welded pipe manufacturing device equipped with a high-pressure fluid injection pipe that injects high-pressure fluid in a direction.