JPH0438220B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an apparatus for manufacturing anti-corrosion coated steel pipes used as foundation piles in civil engineering works such as offshore bridges, etc., and in particular to steel pipes with raised weld beads. A thermoplastic synthetic resin sheet is spirally wrapped around the outer circumferential surface.

[Conventional technology]

For example, in the case of a structure such as a bridge built on the sea, the steel pipe supports, which are welded to steel pipe piles driven into the seabed and protrude above the sea surface, are connected to the tidal zone of the sea surface and the so-called splash zone above it. The parts that are most likely to be exposed to splashes are the most susceptible to corrosion. Therefore, corrosion protection of the portion of the steel pipe support that extends from the tidal zone to the splash zone is particularly important. Conventional corrosion-resistant steel pipes of this type are coated with urethane or epoxy paint to a thickness of about 3 mm, or coated on the outer circumferential surface of the steel pipe by continuously extruding molten polyolefin resin (polyethylene melt extrusion coating). Anti-corrosion coated steel pipes have been used.

[Problem to be solved by the invention]

However, each of the above conventional devices has the following problems.

The cost of painting materials is high.

In the polyethylene melt extrusion coating method, the equipment is very expensive, and the cost of transporting the steel pipe after anti-corrosion treatment increases, and furthermore, damage may occur during handling during transportation, requiring a great deal of effort to repair.

Therefore, this invention wraps a thermoplastic synthetic resin film around the outer circumferential surface of a preheated steel pipe, and in the case of coating by this wrapping, when a weld bead is raised on the surface such as a spiral steel pipe, etc. It is an object of the present invention to solve the above-mentioned conventional problems by providing an apparatus for producing a corrosion-resistant coated steel pipe that eliminates the disadvantage that air pockets are likely to be formed beside the weld bead.

[Means for solving problems]

The apparatus for manufacturing an anti-corrosion coated steel pipe with a weld bead according to the present invention includes a rotating shaft that supports a thermoplastic synthetic resin sheet wound into a coil and is tiltable with respect to the longitudinal direction of the steel pipe. a sheet feeding means configured to feed the sheet from an oblique direction to a steel pipe that is moving relative to the steel pipe; The sheet crimping rolls are elastically supported and each can be set in the direction of the rotating shaft in a direction perpendicular to the sheet feeding direction from the sheet feeding means, and the sheet is applied to the outer circumferential surface of the steel pipe rotating at a constant speed around the axis. The sheet crimping means is configured to apply elastic pressure, and the sheet feeding device relatively moves the sheet supplying means and the sheet crimping means in the longitudinal direction of the steel tube, and the winding angle and the winding pitch of the sheet around the steel tube are adjusted. a heating device disposed before the sheet supply position on the steel pipe to preheat the steel pipe; and a heating device disposed after the position of the crimping roll on the steel pipe to cool the sheet. The system is equipped with a cooling device.

[Effect]

The apparatus for manufacturing a corrosion-resistant coated steel pipe with a weld bead according to the present invention uses a sheet feeding device to feed a wide thermoplastic synthetic resin sheet at a predetermined angle onto the outer peripheral surface of a steel pipe that has been preheated by a heating device. supply. The sheet pressing means presses the supplied thermoplastic synthetic resin sheet against the outer circumferential surface of the steel pipe with a sheet pressing roll, and wraps the sheet in a spiral while expelling air that tends to be caught between the two.

Here, a plurality of sheet crimping rolls are provided in line in the longitudinal direction of the steel pipe, and each roll is elastically supported so as to independently press the sheet on the steel pipe, so that the weld bead of the steel pipe is raised at the part where the weld bead is raised. However, some of the rolls of each sheet crimping roll ride on this, and while climbing over it, move up and down against the steel pipe along the shape of the weld bead, crimping it along the bulge, and the others press the flat part where there is no weld bead. For crimping, the bead portion and other portions can be pressed individually to crimp them. Therefore,
Since the flat part and the bead part are finely crimped, there is no air pocket between the anticorrosive coating and the outer circumferential surface of the steel pipe.

The horizontal slide means optimally adjusts the winding angle and winding pitch of the sheet around the steel pipe according to dimensional changes of the steel pipe, properties of the sheet, and the like.

After the thermoplastic synthetic resin sheet is pressed by the sheet pressing roll, it is cooled by a cooling device to prevent crystallization of the thermoplastic resin due to slow cooling, thereby ensuring its durability.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of an apparatus for manufacturing anti-corrosion coated steel pipes according to the present invention will be described based on the drawings.

1 to 4 show an embodiment of the present invention. For example, a thermoplastic synthetic resin sheet 2 is placed on the outer circumferential surface 1A of a spiral steel pipe 1 in a range of 5 to 10 mm between the side edges of the sheet (for example, It is constructed so that it can be wound spirally while maintaining a uniform narrow interval of 5 mm). Since the steel pipe 1 is a spiral steel pipe as described above, weld beads appear continuously in a spiral shape on the outer surface of the steel pipe 1.

That is, this manufacturing device rotatably supports a thermoplastic synthetic resin sheet 2 wound into a coil shape, and is provided with a horizontal rotating shaft 11 that is tiltable with respect to the longitudinal direction of the steel pipe 1. A sheet supply means 10 is provided. This sheet supply means 1
0 is for a steel pipe 1 that has been preheated, is rotating at a constant speed around the pipe axis, and is moving relatively in the pipe axis direction,
The thermoplastic synthetic resin sheet 2 is continuously fed from an oblique direction at a predetermined angle of inclination. Also provided is a sheet crimping means 30 provided with a plurality of sheet crimping rolls 31 for pressing and fusing the thermoplastic synthetic resin sheet 2 fed from the sheet supplying means 10 to the outer circumferential surface 1A of the steel pipe.

The above-mentioned sheet feeding means 10 and sheet pressing means 3
0 is formed so that the wide thermoplastic synthetic resin sheet 2 can be horizontally rotated in conjunction with the rotation means 20 in order to supply the steel pipe outer circumferential surface 1A from an oblique direction and properly press it.

Furthermore, in order to arbitrarily adjust the winding angle and winding pitch of the thermoplastic synthetic resin sheet 2 spirally wound around the steel pipe 1, the sheet supplying means 1
A horizontal slide means 40 is provided in order to move the sheet pressure bonding means 30, the sheet pressure bonding means 30, and the turning means 20 together in a straight line horizontally in the tube axis direction.

Furthermore, in order to expel air between the outer circumferential surface 1A of the steel pipe and the wrapped thermoplastic synthetic resin sheet 2, a straightening roll 51 presses the thermoplastic synthetic resin sheet 2 over its entire width against the outer circumferential surface 1A of the steel pipe.
is provided with an air expulsion means 50 provided downstream of the sheet pressure roll 31.

To explain in more detail, sheet supply means 10,
Each of the above-mentioned means such as the turning means 20, the sheet pressing means 30, the horizontal sliding means 40, and the air expelling means 50 is arranged on a base 100 via a support 101, and the base 100 moves on a track 102 with the wheels 10.
It is mounted on a trolley 104 that travels through rolling motions. The trolley 104 is driven by a chain (not shown) whose power source is a travel motor 105 mounted on the base 100. Although not shown, a long cantilever beam inserted into the inside of the steel pipe 1 is fixed to the cart 104, and a gas burner and a cooling water spray for heating the steel pipe 1 from the inner side are installed at the tip of the cantilever beam. is installed.

The steel pipe 1 is placed on a drive roll 110 disposed in a space above the track 102, and supported so as to be rotatable at a constant speed about the pipe axis.

A cross beam 111 is attached to the upper part of the support column 101 so as to protrude above the steel pipe 1 so as to be able to swing vertically.The lower surface of the cross beam 111 is supported by a worm jack 114, and the lower end of the worm jack 114 is supported by

A horizontal slide means 40 is provided on the distal end surface of the cross beam 111, and a rotary feed handle 47
This allows the slide table 44 to slide horizontally in the axial direction of the steel pipe 1. Then, the sheet supply means 1 is placed at the tip of the horizontal slide table 44.
0 and a sheet pressure bonding means 30 are rotatably attached via a turning means 20.

The sheet supplying means 10 includes a reel 12, a rotating shaft 11 of which is rotatably supported on a U-shaped support frame 13, and a brake device 14 is provided at the end of the shaft. The purpose of this brake device 14 is to apply appropriate resistance to the feeding of the thermoplastic synthetic resin sheet coil loaded onto the reel 12 and to tension the thermoplastic synthetic resin sheet 2 to the extent that it does not loosen. A simple type of friction brake that allows you to adjust the strength by tightening the brake will suffice.

Reference numeral 15 denotes a guide roll that is suspended and attached to the tip of the support frame 13 via an arm 16.

The sheet supply means 10 is attached to a horizontal slide table 44 via a turning means 20,
By turning a handle (not shown), the sheet supply means 10 can be rotated in a horizontal plane about a pivot shaft 21.

The sheet pressure bonding means 30 is attached to the lower surface side of the horizontal slide table 44 via an arm 32.

The sheet pressure roll 31 has an outer ring made of heat-resistant silicone rubber, for example, and a rotating shaft 3 of the roll.
3 is supported by roll brackets 34, and a floating support shaft 35 and a swing operation shaft 36, which can rotate and move up and down, are provided on the upper surface of each bracket. Second
In the figure, the pivoting shaft 36 is shown only for the left roll bracket 34. The floating support shaft 35 is erected directly above the roll rotation shaft 33, and the swing operation shaft 36 is erected at the end of the roll bracket 34 with a slight distance therebetween. A bearing 37 into which the floating support shaft 35 is inserted is fixed to the front end surface of the arm 32, and a coil spring 39 inserted between the bearing 37 and the roll bracket 34 pushes the sheet pressure roll 31 against the outer peripheral surface of the steel pipe. Suppress against 1A.

A plurality of sheet pressure rolls 31 (five in FIGS. 2 and 4) configured in this manner are arranged at equal intervals along the longitudinal direction of the steel pipe 1 within the width of the thermoplastic synthetic resin sheet 2. The rotation operation shafts 36 of each roll 31 are operatively connected via a link mechanism (not shown). Furthermore, the other end of a swing connecting arm 36A, which has one end fixed to the swing shaft 21 of the swing means 20 and extends downward, is slidably inserted into the swing operation shaft 36 located at the leftmost end in FIG. .

The air expelling means 50 is provided on a shelf 52 that is formed to project from the middle of the main column 101.
That is, a back and forth feed shaft 53 is supported by the shelf 52 so as to be movable back and forth (in the transverse direction of the steel pipe 1). A pair of curved arms 58 are attached to one end of the longitudinal feed shaft 53 in the axial direction of the steel pipe 1. A bearing bracket 60 is attached to the curved arm 58 so as to be movable along the outer circumferential surface 1A of the steel pipe, and is normally fixed in a predetermined position with a handle 61. cooling rolls 65 are each rotatably supported. The straightening roll 51 is hollow and made of silicone rubber, and pressurized air is fed into it from its end. Note that the structure of the cooling roll 65 is almost the same as that described above, but it is made of an iron pipe and is configured to send cold water into the inside thereof.

Next, the effect will be explained.

Thermoplastic synthetic resin sheet 2 in this example
For example, a polyethylene sheet is used in consideration of weather resistance. The polyethylene sheet 2 is a two-layer polyethylene whose outer surface is made of normal polyethylene and whose inner surface is made of modified polyethylene having adhesive properties. The latter modified polyethylene having adhesive properties is preferably one obtained by reacting low-density or high-density polyethylene with maleic anhydride or the like. However, it is also possible to introduce a known adhesive functional group other than maleic anhydride groups. Furthermore, as the plastic synthetic resin, polyolefins other than polyethylene, copolymers with vinyl acetate, etc. can also be used. Further, additives and fillers such as antioxidants and carbon black may be contained as necessary.

When manufacturing anti-corrosion coated steel pipes, steel pipe 1 is heated to 120°C.
Preheat to a temperature in the range of ~240°C, for example, about 200°C in this example. The heating is performed by the drive roll 11
This is done using a gas burner inserted into the inner surface of a steel pipe 1 placed on top of the steel pipe 1 and rotating in the direction of the arrow mark A. Thereby, the outer circumferential surface 1A of the steel pipe is maintained at a temperature necessary for fusing the thermoplastic synthetic resin sheet 2.

The preheated steel pipe 1 rotates around the pipe axis at a constant speed and at the same time is slowly moved relatively along the pipe axis in the direction of the arrow mark B in FIG. This movement is performed by towing the trolley 104 by the travel motor 105. Of course, the steel pipe 1 may also be moved; in short, the steel pipe 1 and the thermoplastic synthetic resin sheet 2 may be moved relative to each other in the axial direction.

In order to spirally wrap the wide thermoplastic synthetic resin sheet 2 around the hot outer circumferential surface 1A of the steel pipe 1, the sheet supply means 10 continuously and obliquely to the tube axis, that is, obliquely at a predetermined angle. Let and supply. The feeding angle and feeding pitch are adjusted by operating the turning means 20 and the horizontal sliding means 40 and, if necessary, by adjusting the speed of the cart 104.

That is, the support frame 13 of the sheet supply means 10 is rotated by the rotation means 20 so that the support frame 13 of the sheet supply means 10 is
1 as an axis, the appropriate sheet feeding angle can be set accurately and easily.

Also, at the same time, the rotation axis 2 of the rotation means 20
The pivoting connection arm 36A fixed at 1 also pivots.
In conjunction with this, the turning operation shaft 36 is operated in conjunction, so that the five sheet pressure bonding rolls 31 connected by the link mechanism 29 integrally turn around the respective floating support shafts 35, as shown in FIG. As shown by the solid line, the rolls 31 are oblique to the tube axis, and each roll 31 can appropriately correspond to the sheet feeding direction so as to press the sheet 2 onto the steel pipe 1.

By adjusting the feeding angle and feeding pitch of the thermoplastic synthetic resin sheet 2, a small distance (for example, 5 mm) is formed between the side edges 2A of the sheet. Then, while maintaining the interval, the thermoplastic synthetic resin sheet 2 is pressed against the outer circumferential surface 1A of the steel pipe by the sheet pressure roll 31. As a result, the outer peripheral surface 1 of the steel pipe can be
The thermoplastic synthetic resin sheet 2 is helically wound while expelling the air between the sheets 2 and A, and the thermoplastic synthetic resin sheet 2 is heat-sealed to the outer circumferential surface 1A of the steel pipe.

In this case, if the sheet crimping roll 31 were formed as a single roll, the steel pipes would be pressed at only one point when they are crossed diagonally, making it impossible to press the entire width of the sheet evenly. , therefore good winding cannot be achieved. On the other hand, it may be possible to use a concave curved roll that matches the curved surface of the steel pipe, but in that case, a large number of rolls would be required for each pipe diameter.

In addition, since the sheet pressure roll 31 is divided into a plurality of parts and individually supported by the floating support shaft 35, the steel pipe 1
The elastic force of the coil spring 39 allows each roll to overcome uneven parts such as weld beads. Therefore, the thickness of the anticorrosive coating layer 5 is prevented from changing depending on the unevenness of the surface of the steel pipe.

Furthermore, the feed handle 4 of the horizontal slide means 40
7 to move the horizontal slide table 44 in the longitudinal direction of the steel pipe 1.
Since the and sheet compression means 30 can be shifted, it is possible to immediately respond to changes in the shape and dimensions of the steel pipe 1, thermal deformation of the thermoplastic synthetic resin sheet 2, and the like. Therefore, it is always possible to maintain an appropriate helical shape and ensure an arbitrary winding interval.

The thermoplastic synthetic resin sheet 2, which has been softened by the heat of the steel pipe 1 and pressed against the steel outer peripheral surface 1A by the sheet pressure roll 31, is then pressed over the entire width of the sheet by the straightening roll 51. Since the straightening roll 51 is easily deformed elastically and adapts well to the uneven shape of the outer circumferential surface 1A of the steel pipe, it can also push out residual air from uneven parts such as weld beads. As a result, the thermoplastic synthetic resin sheet 2 can be brought into closer contact with the outer circumferential surface 1A of the steel pipe, and residual air can be completely expelled.

After winding the thermoplastic synthetic resin sheet 2 to a predetermined length, the thermoplastic synthetic resin sheet 2 is cut with a cutter.

Finally, when the steel pipe 1 is cooled from inside with a cooling spray, a good anticorrosion coating layer is formed on the steel pipe outer circumferential surface 1A, which is completely fused without any residual air.

Note that the gap between the spirally wound thermoplastic synthetic resin sheets 2 is filled separately by pressing a narrow thermoplastic synthetic resin material against the outer circumferential surface 1A of the steel pipe using a jig or the like. That is, on the outer peripheral surface 1A of the steel pipe in the space between the side edges of the thermoplastic synthetic resin sheet,
The gap is filled in by wrapping a thin thermoplastic synthetic resin material and heat-sealing it. Then, the heat of the preheated steel pipe 1 fuses the thermoplastic synthetic resin sheet 2 and the narrow thermoplastic synthetic resin material. The narrow thermoplastic synthetic resin material may be formed in advance by slicing a homogeneous thermoplastic synthetic resin sheet 2 into a width slightly narrower than 5 mm, for example.

The above-mentioned anti-corrosion coated steel pipe manufacturing apparatus has a simple structure, does not require a special installation foundation, and is easy to transport and install. Therefore, by bringing it to a construction site and installing it, it becomes possible to manufacture corrosion-resistant coated steel pipes with weld beads on-site.

In the above embodiments, two-layer polyethylene was used as the thermoplastic synthetic resin sheet, but other thermoplastic synthetic resins may also be used.

Further, it goes without saying that the outer circumferential surface of the steel pipe may be subjected to well-known pretreatment such as rust removal treatment and anticorrosion treatment.

Further, cooling after the formation of the anticorrosive coating may be performed by blowing air onto the outer surface of the steel pipe. Furthermore, in addition to a gas burner, electric heating or high-frequency heating can be used to preheat the steel pipe, and heating may be performed not only from the inner surface of the steel pipe but also from the outer surface.

Furthermore, the straightening roll of the air expelling means is not limited to a pneumatic rubber roll, but may also be a sponge roll, a brush roll, a metal roll, or the like. In short, it is desirable to have a material that can press the entire width of the sheet while adapting well to the uneven shape of the outer circumferential surface of the steel pipe.

〔Effect of the invention〕

As explained above, according to the present invention, on the surface of the steel pipe where the bead is attached to the raised outer surface,
The thermoplastic synthetic resin sheet spirally wound by the sheet supply means is pressed against the weld bead of the steel pipe by a plurality of sheet pressure rolls each elastically supported to press the sheet on the steel pipe independently. Even in areas where there is a bulge, some of the rolls ride on it and while climbing over it, move up and down against the steel pipe along the shape of the weld bead and crimp it along the bulge, while other rolls ride on the weld bead. Since the thermoplastic synthetic resin sheet is sequentially pressed by each roll, the bead portion and other portions can be pressed individually and continuously to be crimped. For this reason, since the flat part and the bead part are finely crimped, no air pockets are formed between the anticorrosive coating and the outer peripheral surface of the steel pipe.

Further, according to the present invention, the steel pipe to which the thermoplastic synthetic resin sheet is crimped as described above after being preheated by the heating device is cooled by the cooling device, so that the thermoplastic synthetic resin is crystallized by slow cooling. It also has the effect of preventing this and ensuring its durability.

[Brief explanation of drawings]

Fig. 1 is a side view showing an embodiment of the manufacturing apparatus for anti-corrosion coated steel pipes with weld beads according to the present invention, Fig. 2 is a front view of the main parts thereof, Fig. 3 is an explanatory diagram of the air expelling means, and Fig. 4 FIG. 3 is a plan view showing the rotating state of the sheet pressure roll. 1 is a steel pipe, 1A is the outer peripheral surface of the steel pipe, 2 is a thermoplastic synthetic resin sheet, 10 is a sheet supply means, 11 is its rotating shaft, 30 is a sheet crimping means, 31 is a sheet crimping roll, 39 is a coil spring, 40 is a horizontal slide The means 44 is a horizontal slide table serving as a feeding device.

Claims (1)

[Scope of Claims] 1. A rotary shaft supporting a thermoplastic synthetic resin sheet wound into a coil shape and having a weld bead on the surface and tiltable in the longitudinal direction of the steel pipe, and relatively movable in the longitudinal direction. a sheet supplying means adapted to supply the sheet from an oblique direction of the steel pipe, and a plurality of sheet supply means arranged in line in the longitudinal direction of the steel pipe, each of which is elastically supported so as to independently press the sheet on the steel pipe. Each of the sheet pressure bonding rolls is provided with a rotation axis direction that can be set in a direction perpendicular to the sheet feeding direction from the sheet feeding means, and the sheet is placed on the outer peripheral surface of the steel pipe where the weld bead is located, which is rotating at a constant speed around the axis. a sheet crimping means configured to apply elastic pressure; and a feeding device for relatively moving the sheet supplying means and the sheet crimping means in the longitudinal direction of the steel tube, and adjusting the winding angle and winding pitch of the sheet around the steel tube. horizontal sliding means adapted to adjust; a heating device disposed before the supply position of the sheet on the steel pipe to preheat the steel pipe; and a heating device disposed after the position of the crimping roll on the steel pipe to cool the sheet. 1. A manufacturing device for a corrosion-resistant coated steel pipe with a weld bead, characterized in that it is equipped with a cooling device that performs the following steps.