JPH07117097A - Method and apparatus for producing composite pipe - Google Patents

Abstract

PURPOSE:To rapidly and easily adjust the thickness irregularity of an inner surface resin coating layer by adjusting the position of a mold or that of a metal pipe to uniformly hold the clearance between the outer peripheral surface of the mold and the inner peripheral surface of a tubular molded metal material in the peripheral direction thereof. CONSTITUTION:A round pipe (a) is produced up to the position exceeding the leading end of a mold and, at this point of time, the non-uniformity of the clearance between the outer peripheral surface 710 of the leading end part of the mold and the inner peripheral surface of the round pipe (a) in the peripheral direction is detected by a detection means 8. The detection quantity is reduced by the operation of the position adjusting means 9 of the mold 7 to uniformize the clearance in the peripheral direction and a resin is extruded from the resin emitting orifice 714 of the mold 7 to apply a resin coating layer to the inner surface of the round pipe. Since the cylindrical resin passage in the horizontal part 71 of the mold 7 is substantially uniform in the peripheral direction thereof and the length of the horizontal part 71 is extended, during a period when the resin flows through the horizontal part 71 of the mold 7, the internal stress based on the resin pressure or viscoelasticity of the resin is sufficiently uniformized in the peripheral direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for producing a composite pipe in which the inner surface of a metal pipe is covered with a resin layer.

[0002]

2. Description of the Related Art Pipes used for transferring fluids for water supply, hot water supply, drainage, air conditioning, etc. are required to have corrosion resistance, chemical resistance, etc., and composite pipes coated with a resin layer on the inner surface of metal pipes are often used. Has been done.

As a method for producing such a composite pipe, a circular pipe forming machine is used to form a strip-shaped metal material into a tubular shape by aligning both side edges thereof in the longitudinal direction, and the metal material joining portion of the tubular formed metal material is welded by a welding machine. And the extrusion die is introduced into the tubular forming metal material through the openings between both side edge portions of the strip-shaped metal material on the inlet side of the circular pipe forming machine, and the resin discharge tip of the die is the joining machine. A method for producing an inner resin-coated metal pipe by coating the resin discharged from the die of an extruder arranged on the downstream side of the inner surface of the tubular metal material after welding and further cutting it to a predetermined length (For example, Japanese Patent Laid-Open No. 3-227218).

In the above composite pipe, it is essential to prevent the uneven thickness of the coating layer as much as possible in order to effectively exhibit the anticorrosion performance by eliminating the local thinning of the resin coating layer on the inner surface. . It is known that an uneven thickness adjusting machine is additionally provided in the above-mentioned composite pipe manufacturing apparatus (for example, Japanese Patent Laid-Open No. 62-198447).

[0005]

As is well known, in adjusting the uneven thickness of the resin extrusion coating, the uneven thickness amount is detected at a position immediately after the resin is extruded, and the uneven thickness adjusting device is operated according to the detected amount. It is ideal to correct the uneven thickness amount within a predetermined allowable value from the viewpoint of preventing material loss, for example, by detecting the uneven thickness amount immediately after extrusion of the resin by X-ray fluoroscopy, It is known that uneven thickness adjustment is performed based on this detection result.

However, in the above-mentioned method for producing a composite pipe, it is considered extremely difficult to detect uneven thickness of the coating layer immediately after extrusion, because the resin is extruded and coated in the metal pipe.

[0007] In the prior art, therefore, the cross section of the inner surface resin-coated metal pipe cut to a fixed length is observed to measure the amount of uneven thickness of the inner surface resin coating layer, and an uneven thickness adjuster is used in accordance with this amount of uneven thickness. Operation until the coating layer thickness is substantially uniform in the circumferential direction,
The uneven thickness measurement and uneven thickness adjustment on the cut surface of the pipe are repeated (the uneven thickness adjusting machine described in JP-A-62-198447 is also used for such uneven thickness adjustment). Therefore, a great deal of time loss and material loss are inevitable.

It is an object of the present invention to provide a method and an apparatus for manufacturing a composite pipe, which can quickly and easily adjust the uneven thickness of the inner resin coating layer when manufacturing the inner resin coated metal pipe.

[0009]

A method for manufacturing a composite pipe according to the present invention is a tubular pipe forming machine in which a strip-shaped metal material is formed into a tube by aligning both side edges of the metal material in a longitudinal direction, and the tubular formed metal is formed. The metal material joining portion of the material is joined, and the extrusion die is introduced into the tubular molding metal material through the openings between both side edge portions of the strip-shaped metal material on the inlet side of the circular pipe molding machine, and the tip of the die is In the method for producing an inner resin-coated metal pipe by coating the inner surface of the tubular molded metal material after the joining with the resin discharged from the die of the extruder arranged on the downstream side of the joining machine, the die or the metal The configuration is characterized in that the position of the tube is adjusted to uniformly maintain the clearance between the outer peripheral surface of the mold and the inner peripheral surface of the tubular formed metal material in the circumferential direction.

The composite pipe manufacturing apparatus according to the present invention is
A circular pipe forming machine for forming a strip-shaped metal material into a tubular shape by aligning both side edge portions in the vertical direction, a joining machine for joining the metal material joining portions of the tubular formed metal material, and an extrusion die having the circular pipe Introduced into the tubular forming metal material through the opening between both side edge portions of the strip-shaped metal material on the inlet side of the forming machine, the tip of the die is provided with an extruder arranged downstream of the joining machine, and the above-mentioned joining In the device for manufacturing the inner surface resin-coated metal pipe by coating the inner surface of the tubular molded metal material that has passed through the machine with the resin discharged from the mold,
Detecting means for detecting the degree of non-uniformity of the clearance between the outer peripheral surface of the mold and the inner peripheral surface of the tubular molded metal material along the circumferential direction, and the position of the mold or metal tube is adjusted according to the above detection amount. It is characterized in that the adjusting means is provided.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of the present invention will be described below with reference to the drawings. 1A is an explanatory diagram showing an example of the manufacturing apparatus according to the present invention, and FIG. 1B is an enlarged explanatory diagram of a portion A of FIG. 1A. Further, FIG. 1C is a sectional view taken along the line of FIG.

In FIG. 1A, reference numeral 2 is a strip-shaped metal material 1.
As the belt-shaped metal material 1, a steel plate, a stainless plate, an aluminum plate, a copper plate, a plated steel plate, or the like can be used. 3 is a strip metal material pretreatment tank or device,
Mechanical treatment such as sandblasting, degreasing treatment with alkali, etc., acid treatment with hydrochloric acid, sulfuric acid, nitric acid, zinc phosphate,
Antirust treatment with iron phosphate, oxalic acid, etc., primer treatment with silane coupling agent, titanium coupling agent, organic titanate, etc. can be performed. Reference numeral 4 denotes a forming machine, in which the strip-shaped metal material 1 is formed into a circular opening a as shown in FIG. 1C by a plurality of forming roll pairs through a U-shaped cross section. .

In FIG. 1 (a), 5 is a circular pipe forming machine, in which the opening circular metal material from the forming machine 4 is abutted on both side edges by a plurality of pairs of forming rolls.
Alternatively, they are formed into a tubular shape under superposition. 6
Is a welding machine, and a machine for performing butt welding or lap welding of both side edges of the tubular metal strip according to the above-mentioned forming form of the circular pipe forming machine 5 can be used. For example, an inert gas arc (TIG or A MIG) welding machine, a high frequency welding machine, etc. can be used.

Reference numeral 70 denotes an extruder main body. Reference numeral 7 denotes an extrusion die connected to the extruder main body 70, which includes a horizontal portion 71, a vertical portion 72, and a box portion 73, as shown in FIG. Opening between the pipe forming machine 5 and the horizontal portion 71 is introduced into the circular pipe by inserting the vertical portion 72 into the opening of the circular metal material (shown by b in FIG. 1C). The tip of the portion 71 is arranged at a position beyond the welding machine 6. The horizontal portion 71 is an outer cylinder 711.
And a core 712, and a cylindrical resin flow path 7 between them.
13 and a resin discharge port 714 opened to the outer periphery of the horizontal part between the outer cylinder front end and the core front end, and the outer peripheral surface of the tip of the core serves as a sizing surface 715. Is molded between the sizing surface 715 at the tip of the core and the inner surface of the tubular metal tube e.

In FIG. 1 (b), 8, ... Detecting means for detecting the degree of nonuniformity of the clearance between the outer peripheral surface 710 of the mold and the tubular molding metal material e along the circumferential direction. That is, for example, a displacement gauge for detecting the radial displacement of the same clearance with respect to the center of the mold horizontal portion 71 is located at two or more different positions (90 ⁰ relative to each other) near the resin discharge port of the mold horizontal portion 71 on the same circumference. At two locations separated by an angle of 1
In many cases, it is set at three places separated by an angle of 20 ⁰ , four places separated by an angle of 90 ⁰ , and the like. ) Is installed in.

The displacement gauge may be a non-contact type displacement gauge using laser light or sound waves, or the displacement of a spring may be measured by a pressure change of gas or the like, or an electric quantity such as a piezoelectric element may be measured. It is possible to use a contact-type displacement meter which is measured in.

The mold 7 is provided with position adjusting means 9 for adjusting the position of the horizontal portion 71 in the circular pipe (tubular formed metal material e). As the position adjusting means, as shown in FIG. 2 (a), small jacks 92, ... Are attached to the die receiving base 91, and the die 7 is moved up and down to move the tip of the horizontal portion of the die and the inner circumference of the circular pipe. , The bolts 93, ... Are attached to the die 7 and the distance between the flange portion 700 of the die 7 and the receiving base 91 is changed to change the die position. Adjusting configurations and the like can be used.

In FIG. 1A, 10 is a cooling device.
11 shows a standard length cutting device. Above
As shown in FIG.
The length of the circular pipe forming machine 5 is L₁, Welder 6 resin injection of mold
The distance to the exit 714 is L₂If so, the horizontal part 7 of the mold
The length of 1 is approximately (L₁+ L₂). The circular pipe forming machine
5 length L ₁Is an open circular shape sent to the molding machine 5.
The opening width of the metal material a [in (c) of FIG.
The wider is shown, the longer it needs to be (open circle)
The wider the opening width of the, the larger the amount of molding for molding into a circular pipe.
And the molding amount per unit length of the molding machine, that is, the molding rate
Under the same conditions, the larger the molding amount, the longer the molding machine
There is a need to). Therefore, in (c) of FIG.
The thickness of the vertical portion 72 of the mold is to reduce the resin flow resistance.
It must be thick enough to be
It is necessary to widen the opening width of the
The length L of the circular pipe forming machine 5₁Is quite long
It Also, from the welding machine 6 to the resin discharge port 714 of the mold.
Distance L₂For this, make sure you have enough welds between
Do not allow the resin to deteriorate due to welding heat by natural cooling
It has been quite long. Therefore, the horizontal part 71 of the mold
Length of (L₁+ L₂) Is quite long. example
For example, as a metal material, it has a thickness of 2.8 mm and a width of 359 mm.
Rolled steel plate is used, the inner diameter of the circular pipe is 108.7 mm, and T
When using an IG welder, the horizontal mold part 71 is approximately 600.
mm.

The method of manufacturing a composite pipe according to the present invention can be carried out by using the above-mentioned manufacturing apparatus, and is shown in FIGS.
First, the circular pipe e is manufactured to a position beyond the tip of the mold, and at this time, the circumferential non-uniformity of the clearance between the outer peripheral surface 710 of the mold tip and the inner circumference of the circular pipe e is detected. 8 and the position adjusting means 9 of the mold 7 is operated to reduce the amount of detection to make the clearance uniform in the circumferential direction. After that, the resin is extruded from the resin discharge port 714 of the mold 7 to form a circle. A resin coating layer is applied to the inner surface of the tube. Therefore, the cylindrical resin flow path 713 in the horizontal portion 71 of the mold 7 is substantially uniform in the circumferential direction, and the length of the horizontal portion 71 is sufficiently long as described above. Therefore, while the resin flows in the mold horizontal portion 71, the internal stress due to the resin pressure and viscoelasticity is sufficiently uniformized in the circumferential direction, and the sizing surface 715 of the mold tip and the circular pipe e. If the clearance with the inner circumference is kept uniform in the circumferential direction, the thickness of the resin coating layer can be made sufficiently uniform in the circumferential direction.

During production of the composite pipe, if the position of the tip of the die is displaced for some reason and the inner surface resin coating layer is unevenly thickened, the outer periphery 710 of the die tip and the inner circumference of the circular tube e are separated. The clearance between them becomes non-uniform in the circumferential direction, and the non-uniformity is detected by the detection means 8. Therefore, if the die position adjusting means 9 [(c) in FIG. 1] is operated according to the detected value to reduce the detected value, the degree of nonuniformity of the clearance along the circumferential direction is determined. The thickness can be kept within the limit, and uneven thickness of the inner surface resin coating can be suppressed to make the thickness substantially uniform.

The die 7 is supported by a cantilever type, and the displacement of the tip of the die occurs with the cantilever end as a fulcrum, and the distance from this fulcrum to the displacement gauge is lengthened. Since the displacement received by the displacement gauge, and thus the detection sensitivity, can be increased, it is desirable to dispose the displacement gauge 8 on the tip side of the mold as much as possible.
It is arranged in the range of up to 200 mm.

In the above-mentioned configuration example of the present invention, the joining portion in the longitudinal direction of the circular pipe is joined by welding, but it is also possible to use another joining method, for example, a folded joint. .

Further, a method of adjusting the position of the mold side is used for the relative position adjustment of the mold with respect to the circular pipe.
It is also possible to use a method of adjusting the position of the cylindrical metal material side in a two-dimensional direction (usually the vertical direction) orthogonal to the lengthwise direction.

As the resin used for the above inner surface coating, known synthetic resins can be used. In particular, it is desirable to use a synthetic resin having excellent adhesiveness to a metal, for example, silane-grafted polyethylene, carboxylic acid-modified polyethylene,
Polyvinyl acetate, polyvinyl acetal, polyvinyl alcohol, polyamide and the like are suitable.

[0025]

[Function] Since the resin passage in the mold is uniform in the circumferential direction and is sufficiently long, the resin pressure and internal stress are sufficiently uniform in the circumferential direction while the resin flows in the mold. Will be
If the clearance between the sizing surface on the outer periphery of the mold tip (the outer peripheral surface of the mold tip on the downstream side of the resin discharge port) and the inner peripheral surface of the tubular molded metal material is kept uniform in the circumferential direction, the inner surface resin coating layer The thickness can be made sufficiently uniform in the circumferential direction.

If the clearance between the sizing surface on the outer periphery of the tip of the mold and the inner peripheral surface of the tubular formed metal material fluctuates, the variation is followed to the outer peripheral surface of another mold (the outer periphery other than the sizing surface). The clearance between the surface) and the inner circumferential surface of the tubular formed metal material also fluctuates, and if the latter clearance non-uniformity in the circumferential direction is reduced, the former clearance non-uniformity along the circumferential direction can also be reduced. From the latter, the latter circumferential non-uniformity of the clearance is detected, and the position of the die or metal tube is adjusted by the detected amount to reduce the circumferential non-uniformity of the same clearance, and the sizing surface of the outer periphery of the die tip is adjusted. The clearance between the tubular molded metal material and the inner peripheral surface can be uniformly maintained in the circumferential direction, and the thickness of the inner surface resin coating layer can be uniform in the circumferential direction.

[0027]

EXAMPLE According to the present invention, a composite pipe having a resin coating layer on the inner surface can be manufactured while preventing uneven thickness of the resin coating layer on the inner surface. This can be confirmed from the following examples.

The strip-shaped metal material has a width of 359 mm and a thickness of 2.
An 8 mm hot rolled plate was used, and the pretreatment was degreasing treatment with alkali and oxide film removal treatment with nitric acid. The length of the horizontal portion of the mold and 600 mm, vertically position upstream 50mm resin discharge port was fitted with a piezoelectric element in four positions spaced an angle of 90 ⁰ to each other right and left. The mold position adjusting means shown in FIG. 2B is used, and the silane-grafted polyethylene (polyethylene 100) is used while adjusting the bolts of the mold adjusting means so that the outputs of the four piezoelectric elements are equalized. 1 part by weight vinyltrimethoxysilane
Parts by weight and 0.04 parts by weight of di-t-butylperoxide) were extruded at 190 ° C. and coated with an inner surface resin layer having a design thickness of 2.5 mm to obtain a composite pipe. The thickness was measured at 16 equal parts in the circumferential direction of the resin coating layer on the inner surface of this composite pipe, and the variation was found to be within 10%, and the absolute value was only ± 0.25 mm.

On the other hand, when the conventional method for suppressing the uneven thickness by repeatedly measuring the uneven thickness of the inner resin coating layer on the cut surface of the composite pipe and operating the mold position adjusting means is used, Variation is about 25%, and absolute value is ± 0.6m
It reached m.

[0030]

EFFECTS OF THE INVENTION The present invention is configured as described above, and when a strip-shaped metal material is formed into a tubular shape, the joining portions of the tubular metal materials are joined, and the inner surface of the joined metal tube is extruded and coated with resin, Due to the circumferential uniformity of the resin extrusion of the mold, if the clearance between the outer peripheral surface of the mold and the inner peripheral surface of the tubular formed metal material is kept uniform along the circumferential direction, the uneven thickness of the coating layer will be substantially eliminated. In view of the above prevention, it is possible to detect the uneven thickness of the coating layer at the position of the mold, and the relative value between the mold and the metal tube is adjusted by this detected value to correct the uneven thickness. Therefore, the inner surface resin-coated metal tube can be manufactured with the inner surface coating layer being sufficiently uniform and material loss being substantially eliminated.

[Brief description of drawings]

1 (a) is an explanatory view showing an embodiment of a manufacturing apparatus according to the present invention, and FIG. 1 (b) is A in FIG. 1 (a).
1 is an enlarged explanatory view of a portion, and FIG. 1C is a sectional view taken along the line HB in FIG.

2A and 2B are explanatory views showing different examples of mold position adjusting means used in the manufacturing apparatus according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 band metal material 5 circular pipe forming machine 6 joining machine 70 extruder main body 7 extrusion die 714 discharge port 710 die outer peripheral surface e tubular forming metal material 8 detection means 9 die position adjusting means

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Claims (2)

[Claims] 1. A circular pipe molding machine is used to form a strip-shaped metal material into a tubular shape by aligning both side edges thereof in the longitudinal direction, and joining the metal material-bonded portions of the tubular molded metal material, and the extrusion die is the above-mentioned. The metal of the extruder is introduced into the tubular forming metal material through the openings between both side edge portions of the strip-shaped metal material on the inlet side of the circular pipe forming machine, and the tip of the die is arranged on the downstream side of the joining machine. In a method for producing an inner surface resin-coated metal pipe by coating the resin discharged from a mold on the inner surface of the tubular metal molding material after joining, the outer peripheral surface of the mold and the tubular metal molding are adjusted by adjusting the position of the metal mold or the metal pipe. A method for manufacturing a composite pipe, characterized in that the clearance between the inner peripheral surface of the material and the peripheral surface is kept uniform in the circumferential direction. 2. A circular pipe forming machine for forming a strip-shaped metal material into a tubular shape by aligning both side edges thereof in the longitudinal direction, a joining machine for joining the metal material joining portions of the tubular formed metal material, and an extrusion die. An extruder in which the die is introduced into the tubular forming metal material through the openings between both side edges of the strip-shaped metal material on the inlet side of the circular pipe forming machine, and the tip of the die is arranged on the downstream side of the joining machine. Equipped with
In an apparatus for manufacturing an inner surface resin-coated metal pipe by coating the resin discharged from a mold on the inner surface of the tubular molded metal material that has passed through the joining machine, between the outer peripheral surface of the mold and the inner peripheral surface of the tubular molded metal material. A detection means for detecting the degree of non-uniformity of the clearance along the circumferential direction, and an adjustment means for adjusting the position of the mold or the metal tube in accordance with the above detection amount are provided. Manufacturing equipment.