JPH03281768A - Device for repair-plating bead cutting zone of plated resistance welded steel pipe - Google Patents

Abstract

PURPOSE:To obtain the device for repair-plating the title cutting zone with the adhesion between the repair plating layer and the base material, weldability, etc., improved by increasing the supply of a nonoxidizing gas to a seal hood when continuously calculated values of the dew point and O2 concn. of the atmosphere in the hood exceed a specified value. CONSTITUTION:The padding on the outer surface of the bead zone 3 of a plated resistance welded steel pipe P is cut by a cutting tool 4, and a nonoxidizing gas is supplied into a seal hood 6 provided on the downstream side of the tool 4 at all times. A molten repair metal having a composition identical or similar to that of the plating layer of a metal-plated band steel S is continuously discharged from a nozzle 5 to the vicinity of the bead cutting zone of the traveling pipe P when the cutting zone of bead 3 is still hot to repair-plate the bead cutting zone. In this case, the dew point and O2 concn. of the nonoxidizing gas extracted 9 to the tool 4 side from the nozzle 5 in the hood 6 are continuously measured 10 and 11' a large amt. of the nonoxidizing gas is supplied 12 into the hood 6 when the measured values exceed a specified value, and the set value in the hood 6 is kept below the specified value when the measured value reaches the set value.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a method for applying a plating layer of a metal-plated steel strip continuously to a weld bead cut portion of a plated electric resistance welded steel pipe manufactured using a metal-plated steel strip as a material. Repair plating of weld bead cut parts of galvanized electric resistance welded steel pipes that can uniformly form a good repair plating layer on the weld bead cut parts by hot-dipping repair plating metal with the same or similar composition to the weld bead cut parts. It is related to the device.

[Conventional technology]

Steel pipes plated with Zn, M, or Zn-12 alloys have excellent corrosion resistance, weather resistance, heat resistance, etc., and are therefore widely used as building materials, automobile parts, electrical equipment materials, and the like. These metal-plated steel pipes have been manufactured by applying metal plating, such as by hot rVJ immersion plating or electroplating, to pipe materials that were previously made by welding or drawing.

However, recently, except for some applications, in order to reduce manufacturing costs, copper strips that have been plated with metals such as Zn, Ml, or Zn-M alloys are used as raw materials, and the strips are shaped into widths using forming rolls. The mainstream method is to manufacture plated electrical I11 rust pipes by bending the pipe in the direction of the pipe, forming it into a tubular shape, and then welding the abutting portions of both side edges by electric resistance welding.

However, with this method, the weld bead and the plating layer in the vicinity are destroyed by the heat during electric resistance welding, so
In that part, the original properties such as corrosion resistance and heat resistance are impaired. Further, a plating layer having such characteristics does not originally exist in the weld bead forming a part of the surface of the plated electric Mtf4 tube.

Therefore, there is a method for imparting properties such as corrosion resistance and heat resistance to the weld bead and its immediate vicinity (hereinafter collectively referred to as the weld bead), which have not conventionally had such properties. , After electric resistance welding, the build-up of the weld bead is cut and removed, and that part (hereinafter referred to as the weld bead cut part)
A method of forming a plating layer by thermally spraying a repair plating metal of the same or similar composition to the plating layer of the raw material has been implemented. However, the repair plating layer formed in this way is not essentially a layer that has reacted metallurgically homogeneously with the steel base, but is different from the plating layer formed on the material on the side where the weld bead is formed. They have different structures. In other words, this thermal sprayed repair plating layer only adheres to the cut part of the weld bead due to the anchoring effect, so it has poor adhesion, and since the thermal spraying is performed in an oxidizing atmosphere, the repair plating layer itself may contain oxides. It becomes porous.

Therefore, the properties such as corrosion resistance and heat resistance are significantly inferior to the plated layer of the material.

These problems can be solved by improving the thermal spraying technology to strengthen and homogenize the bond between the repair plating layer and the steel substrate, or by applying metal powder mixed with flux to the weld bead and heating it. Attempts have been made to form a repair plating layer, but the repair plating layer formed in this way cannot be constructed like the good plating layer that the material before pipe making has. So the problem is not resolved.

[Problem to be solved by the invention]

The present invention solves the above-mentioned conventional problems, and the repair plating layer formed on the cut portion of the weld bead is made of original Zn.

To provide a repair plating device for a weld bead cut part of an electric resistance welded steel pipe, which has good adhesion to the material like the M or Zn-AQ alloy plating layer and has excellent performance such as weldability, corrosion resistance, and heat resistance. That is the issue.

[Means to solve the problem]

As a result of intensive research to solve the above problems, the inventors of the present invention have found that, immediately after electric resistance welding, while the welding bead is still hot, the welding bead can be cut and repair hot-dip plating metal can be attached to the welding bead cut using a non-oxidizing gas. Method performed under atmosphere (Japanese Unexamined Patent Publication No. 61-1245
No. 59, JP-A-62-13561.

(Refer to JP-A No. 62-109958), a very excellent effect was obtained, but the thickness of the plated steel strip for pipe making, the steel type,
The manufacturing process may vary depending on various conditions such as the pipe diameter, and even when manufacturing 1'ti steel pipes with the same plating, the manufacturing conditions are not always constant due to fluctuations in welding conditions, etc., so at least welding The non-oxidizing gas atmosphere in the seal hood that covers the weld bead cutting area from the bead cutting position to the nozzle that discharges hot-dip repair metal and its vicinity is not always maintained in a state that provides good plating performance. As a result, poor adhesion of repair hot-dip plating metal to the cut portion of the weld bead and non-plating occurred.

Therefore, the present inventors considered it important to understand the relationship between the atmosphere inside the seal hood and plating performance in order to perform good repair plating, and as a result of various studies, they found that good repair plating could not be performed in the past. This is because an oxide film is formed on the weld bead cut part during the process from the weld bead cutting position to the nozzle for dispensing hot-dipped metal for repair, and the factor that has the most influence on the formation of this oxide film is the seal hood. The dew point and oxygen concentration of the atmosphere inside the seal hood are determined to be the same, and the dew point and oxygen concentration of the atmosphere inside the seal hood are continuously measured. When the measured values exceed a predetermined value, non-oxidizing gas is removed from the seal hood. He completed the invention with the belief that the objective could be achieved by opening a solenoid valve installed in a supply path that supplies a large amount of water to the interior of the body, and closing the solenoid valve when the measured value reached a set value. .

[Structure of the invention]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a repair plating device for a weld bead cut portion of a plated electric resistance welded steel pipe according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic front view of one embodiment of the device of the present invention, FIG. 2 is an explanatory plan view of the same, FIG. 3 is an explanatory front view of the seal hood section of the device of the present invention, and FIG. FIG. 3 is an enlarged cross-sectional view taken along line X-X.

In the drawing, S is a material steel strip consisting of a metal-plated steel strip plated with Zn, All or Zn-AQ alloy, and this material steel strip S is continuously moved horizontally during forming by a pipe making machine. A plated electric resistance welded steel pipe which is curved in the width direction by roll 1 (only the last roll is shown) and formed into a tubular shape, whose both side edges are abutted by squeeze roll 2, and the abutted portion &itM welded to have a weld bead 3. It becomes P.

The device of the present invention is a device that is installed continuously in this pipe making machine, and includes a cutting tool 4 for cutting the outer surface of the weld bead 3 of the plated electric resistance welded steel pipe P immediately after being manufactured in the pipe making machine, and
The weld bead cut part of the plated ERW steel pipe P passing through the cut part of the weld bead 3 on the downstream side of A nozzle 5 that continuously discharges a repair hot-dip metal of the same composition, a seal hood 6 that covers the weld bead cutting portion from at least the rear side of the cutting tool 4 to the nozzle 5, and the immediate vicinity thereof, and a seal hood 6 that A non-oxidizing gas such as nitrogen gas or argon gas is inserted from a gas source 7a into, for example, the seal hood 6 from the front and rear, and the gas blowing hole 7ba is provided along the ceiling and has a hole diameter of 1 to 2 mm.
A non-oxidizing gas supply section 7 that constantly supplies a constant amount of non-oxidizing gas in the form of a shower by two non-oxidizing gas supply W7b which are reasonably small and have a large number of non-oxidizing gases spaced at intervals of 5 to 10 mm, and furthermore, a seal hood 6 comes out of the non-oxidizing gas supply section 7, which has a large number of non-oxidizing gas feeds W7b, and the electric resistance stitching which comes out from the seal hood 6. It is the same as the technical concept described in the three patent publications previously proposed by the present applicant. In addition to the above-mentioned configuration, the device of the present invention is characterized by a seal hood 6.
A fog point measuring means 10 for continuously measuring the n point and oxygen concentration of the non-oxidizing gas extracted from inside, preferably through an extraction pipe 9 having an extraction port on the side of the bite 4 from the nozzle 5 in the seal hood 6; An electromagnetic valve installed in an oxygen concentration measuring means 11 and a supply path 12 that supplies a large amount of non-oxidizing gas into the seal hood when the value measured by the dew point measuring means 10 or the oxygen concentration measuring means 11 exceeds a predetermined value. The control box 14 is equipped with a control box 14 that issues a signal to open the seal hood 13 and close it when the measured value reaches a set value.Furthermore, the contact portion of the seal hood 6 with the plated electric resistance welded steel pipe P is made of metal fiber nonwoven fabric 6a. It lies in becoming. When using this metal fiber nonwoven fabric 6a, a press plate such as metal fiber nonwoven fabric 6.1 (manufactured by Nippon Seisen Co., Ltd., trade name: Naslon) made of felted stainless steel fibers is attached to the side wall of the seal hood main body 6b. 6c and fixing screw 6d. In addition, 15 is a support roll for passing the electric resistance welded plated electric resistance welded steel pipe P horizontally and without vertical vibration, and 16 is a support roll for repairing the nozzle 5. This is a repair hot-dip plating metal tank for continuously supplying hot-dip plating metal.

[For production]

To perform repair plating on a weld bead cut portion of a plated electric resistance welded steel pipe using the apparatus of the present invention having such a structure.

In the process of continuously moving the raw material steel strip S horizontally, it is curved in the width direction by the forming roll l of the pipe making machine to form it into a tube shape, and the both edges of the raw material steel cloth S are butted against each other by the squeeze roll 2 to form the material into a tube. Weld bead 3 by electric resistance welding on the butt part.
Using the device of the present invention, which is installed immediately after the plated ERW steel pipe P is formed, the build-up on the outer surface of the weld bead 3 of the plated ERW steel pipe P is cut with a cutting tool 4. The weld bead 3 passes through the cut part while it is still hot under an atmosphere of non-oxidizing gas that is always supplied in a fixed amount from the non-oxidizing gas supply section 7 into the seal hood 6 installed on the downstream side of the Repair plating is performed by continuously discharging repair hot-dip metal having the same or similar composition to the plating layer of the metal-plated steel strip S from the nozzle 5 at the weld bead cutting part of the ERW steel pipe P and in the very vicinity thereof. At this time, the dew point and oxygen concentration of the non-oxidizing gas extracted through the extraction pipe 9 having an extraction port on the side of the cutting tool 4 from the nozzle 5 in the seal hood 6, preferably in the seal hood 6, are continuously measured. The dew point measuring means 10 and the oxygen concentration measuring means 11 measure the dew point, and when the measured value by the dew point measuring means 10 or the oxygen concentration measuring means 11 exceeds a predetermined value, a signal from the control box 14 sends non-oxidizing gas to the seal hood. A solenoid valve 13 installed in a supply path 12 for supplying a large amount of water into the interior of the tank 6 is opened, and when the measured values by the dew point measuring means 1O and the oxygen concentration measuring means 11 reach the set values, the solenoid valve 13 is closed and the seal is closed. The dew point and oxygen concentration of the non-oxidizing gas in the hood 6 are always kept below predetermined values. In this way, in order to always maintain the n-point of non-oxidizing gas and oxygen concentration in the seal hood 6 below a predetermined value, it is necessary that the seal hood 6 has good airtightness, and the plating of the seal hood 6 When the contact portion with the electric resistance welded steel pipe P is made of the metal fiber nonwoven fabric 6a, the metal fiber nonwoven fabric 6a has elasticity and is excellent in heat resistance and abrasion resistance, so it can withstand long-term use. It is preferable because it can be obtained. In this way, when the dew point and oxygen concentration of the non-oxidizing gas in the seal hood 6 are always kept below the predetermined values, the plating adhesion of the repair hot-dip metal to the weld bead cut part of the galvanized ERW steel pipe P is reduced. Since the wettability is improved and stable repair plating can be continuously obtained, high-quality plated electric resistance welded steel pipes PfJ can be manufactured.

〔Example〕

Hereinafter, an example in which the apparatus of the present invention was used to perform repair plating on a weld bead cut portion of an ETLL pipe will be specifically described.

Example 1 Hot-dip galvanized steel strip with plate thickness of 1.6 mm [zinc coating amount: 120
g/+w” (one side)] as shown in Figures 1 and 2, passed through a pipe making machine to form a tube, and then butt-welded both sides of the pipe to form a continuous plated electric resistance welded steel pipe. In the apparatus of the present invention shown in Fig. 3, which is manufactured and installed continuously in a pipe making machine from 1 to 20, a bath temperature of 470°C is placed in a metal tank from zinc containing 0.2% by weight. When performing repair plating by continuously discharging repair hot-dip metal from a nozzle onto the cut portion of the still hot weld bead, the contact area with the galvanized ERW steel pipe is as shown in Figures 3 and 4. Gold Ji4In fiber nonwoven fabric made of felted stainless steel fibers (
An electric resistance welded W4 pipe with an outer diameter of 25.4 mm was manufactured by creating a nitrogen gas atmosphere inside the seal hood made of Nippon Seisen Co., Ltd., U product name Naslon. At this time, the atmosphere gas in the seal hood was set to always have a dew point of 35° C. or lower and an oxygen concentration of 25 ppm or lower. In other words, the length of the seal hood that covers the weld bead cutting part and its vicinity from the rear side of the cutting tool to the plating nozzle is 500 IItlI, and the length of the seal hood that covers the weld bead cutting part and its vicinity from the rear side of the cutting tool to the plating nozzle is 10 nm along the ceiling inside the seal hood that constitutes the non-oxidizing gas supply section.
The gas supply to the seal hood from two non-oxidizing gas feed pipes with holes 2 m in diameter spaced apart by n is normally 25 Q.
/min, but the dew point and M element concentration of the non-oxidizing gas extracted through the extraction pipe with the extraction port on the side of the bite from the nozzle in the seal hood are measured using a dew point measuring means (Hygrometer manufactured by Paname 1 to Rixner 1). ) and oxygen concentration measuring means (
Manufactured by Teledyne Analytical Instruments, Inc.
The dew point and oxygen concentration are continuously measured using Micro Fuel Cell (trade name) and the measured values are sent to the control box.
If the oxygen concentration exceeds 30 ppm, a large amount of non-oxidizing gas (30 to 50 Q
/vain) is opened to the solenoid valve installed in the supply path, and the dew point or oxygen concentration at which the measured value exceeds the predetermined value is the set value (-40°C for dew point, 20 ppm for oxygen concentration) ), the solenoid valve was closed to maintain a good atmosphere inside the seal hood.

The setting values for the dew point and oxygen concentration of the atmosphere inside the seal hood were set as shown above based on the results of investigating the influence of the dew point inside the seal hood and #blue concentration on the precipitability shown in Table 1. This is what I selected.

In this Table 1, the determination of the fitability is made by bending the repaired plated layer to a radius of 150m+ with the repaired plated layer on the outside.
A cellophane tape was attached to the surface of the repair plating layer and the cellophane tape was peeled off, and the repair was evaluated based on the adhesion of the repair plating layer and the appearance of the plating.

○: No peeling, good appearance △ Partial peeling, good appearance A plating layer can be stably obtained, and the repair plating layer has far superior plating adhesion and wetting properties compared to plated ERW steel pipe obtained by conventional methods, and has significantly improved corrosion resistance and heat resistance. It was intended to improve the results.

Example 2 A hot-dip aluminized steel strip with a plate thickness of 1.6 mm [aluminum coating amount 90 g/m2 (one side)] was prepared in the same manner as in Example 1 to have an outer diameter of 3.
A plated electric resistance welded steel pipe of 1.8+uo+ was manufactured.

As the repair plating metal bath, an aluminum bath to which 9% by weight of Si was added was used, and the plating bath temperature was 700°C.

As a result, there was no occurrence of unplated material, and a good repair plating layer was stably obtained.Furthermore, the repair plating layer was higher than that of the ERW steel pipe obtained by the conventional method as in Example 1. It has far superior plating adhesion and wettability, and has significantly improved corrosion resistance and heat resistance.

〔Effect of the invention〕

As described in detail below, according to the repair plating device for the weld bead cut portion of a plated ERW steel pipe according to the present invention, Zn, Ml
Alternatively, in the manufacturing process of galvanized ERW steel pipes made from Zn-AQ gold alloy plated steel strip, a seal hood is used to extend the area from the cutting position of the weld bead to the attachment point of repair hot-dip plated metal to the molten bead cutting area. For the non-oxidizing gas atmosphere inside the seal hood, non-oxidizing gas is supplied so that the dew point and oxygen concentration are always below the set values, and the structure of the seal hood is isolated from the outside air. By using metal fiber non-woven fabric in the area to be welded, the atmosphere inside the seal hood is maintained well, and the adhesion and wettability of the hot-dip metal for repair to the weld bead cutting area is improved. It is possible to continuously obtain stable repair plating using this method, and it not only improves corrosion resistance and heat resistance performance, but also improves productivity and yield, and its industrial value is extremely large. It is something.

[Brief Description of the Drawings] Fig. 1 is a schematic front view of one embodiment of the device of the present invention, Fig. 2 is an explanatory plan view of the same, Fig. 3 is an explanatory view of the JF plane of the seal hood portion of the device of the present invention, and FIG. 4 is an enlarged cross-sectional view taken along the line X--X in FIG. 3. In the drawings 1...Forming roll 2...Squeeze roll 3...Welding bead 4...Bite 5...Nozzle 6...Seal hood 6a...Metal fiber Non-woven fabric 6b...Seal hood body 6c...Press plate 6d...Stopper plate...Non-oxidizing gas supply section 7a...Gas source 7b...Non-oxidizing gas supply Inlet pipe 7ba... Gas blowout hole 8... Straightening roll 9... Extraction pipe 10... Dew point measuring means 11... Oxygen concentration measuring means 12... Supply path 13. ... Solenoid valve 14 ... Control box 15 ... Support roll 16 ... Hot-dip metal tank for repair S ... Material steel strip P ... Plated electric resistance welded steel pipe

Claims (1)

[Scope of Claims] 1. A device that is installed continuously in a device that continuously manufactures galvanized electric resistance welded steel pipes by moving a metal plated steel strip, forming it into a tubular shape, and butting and electric resistance welding the both side edges of the metal plated steel strip. And,
A cutting tool for cutting the outer surface of the weld bead of the galvanized ERW steel pipe, and a cutting tool for cutting the weld bead of the galvanized ERW steel pipe passing downstream of the cutting tool, and plating of the metal-plated steel strip in the very vicinity thereof. a nozzle that continuously discharges a repair molten plating metal having the same or similar composition to the layer; a seal hood that covers the weld bead cut portion from at least the rear side of the bit to the nozzle and the immediate vicinity thereof; and the seal. a non-oxidizing gas supply unit that always supplies a constant amount of non-oxidizing gas into the hood;
a dew point measuring means and an oxygen concentration measuring means that continuously measure the dew point and oxygen concentration of the non-oxidizing gas extracted from inside the seal hood through the extraction pipe; A control box that opens a solenoid valve installed in the supply path that supplies a large amount of non-oxidizing gas into the seal hood when the measured value exceeds the set value, and issues a signal that closes the solenoid valve when the measured value reaches the set value. A repair plating device for a weld bead cutting part of a mated ERW steel pipe, characterized in that: 2. The repair plating device for a weld bead cut portion of a plated electric resistance welded steel pipe according to claim 1, wherein the contact portion of the seal hood with the plated electric resistance welded steel pipe is made of a metal fiber nonwoven fabric.