OA17188A - Electroplating device. - Google Patents

Abstract

An electro plating device includes a pipe inside seal mechanism which occludes an inner channel of a steel pipe, a tubular insoluble electrode which is disposed in a pipe end so as to be opposite to a female screw, a plating solution feed mechanism which includes a plurality of nozzles which extend radially with a pipe axis of the steel pipe as a center, and a pipe end seal mechanism which accommodates the nozzles there inside and is mounted to the pipe end, when viewed in the pipe axial direction, a tip of each of the nozzles is positioned between the female screw and the insoluble electrode, and each of the nozzles injects the plating solution toward a direction which intersects an extension direction of the nozzle, the direction being a rotational direction of a clockwise direction or a counterclockwise direction in which the pipe axis is the center.

Description

[Type of Document] SPECIFICATION [Title of the Invention] ELECTROPLATING DEVICE [Technical Field]

The présent Invention relates to an electro plating device which forms an electro plating layer on a surface of a female screw carved on an inner clrcumferential surface of a pipe end of a steel pipe.

Priority is claimed on Japanese Patent Application No. 2012-148476, filed on July 2, 2012, and the contents of which are Incorporated herein by référencé.

[Background Art]

In order to collect naturel gas or crude oil from underground, a pit is dug toward a naturel gas field or an oll field existing at several thousand meters from the ground surface to underground, and it Is necessary to install a large transport pipe to the pit. In the transport pipe, a plurality of long steel pipes (so-called oil-well pipes) are connected to each other In a line. In recent years, in the viewpoint of productivity Improvement, a need for a screw joint (so-called Intégral joint) for a steel pipe capable of directly connecting the oil-well pipes without using a coupling is increasing. The oil-well pipe having a male screw formed on an outer drcumferential surface of one pipe end and a female screw formed on an inner drcumferential surface of the other pipe end is used as the intégral joint. That is, the intégral joint indudes the male screw (pin) which is spirally carved on the outer drcumferential surface of one pipe end of the oil-well pipe, and the female screw (box) which Is spirally carved on the Inner drcumferential surface of one pipe end of the other oil-well pipe connected to the oil-well pipe.

Conventionaliy, when the oil-well pipes are secured to each other, in order to prevent

- 1 17188 selzure ofthe Joint portion, lubricatlng oll (API dope) Induding heavy metals such as Pb Is applied to at least one of the male screw and the female screw of the oil-well pipe. On the other hand, In a région In which use of the API dope is limited under a severe envlronmental régulation, environment protective lubricating oil (green dope) not induding heavy metals may be used. Slnce lubridty of the green dope is worse than that of the API dope, the selzure easily occurs in the joint portion. Thereby, when the green dope is used as the lubricating oil, in order to compensate for lack of the lubridty of the green dope and prevent occurrence of the selzure, it is préférable that an electro platlng layer such as copper be formed on at least one surface of the male screw and the female screw carved on the pipe end of the oil-well pipe.

For example, in Patent Document 1 below, a device Is disdosed which forms an electro plating layer on a surface of a male screw (pin) carved on one pipe end of the oil-well pipe, that is, on an outer drcumferential surface of one pipe end of the oil-well pipe.

(Prior Art Document] [Patent Document] (Patent Document 1] Japanese Examined Patent Application, Second Publication No. S63-6637 [Disdosure of the Invention] [Problem that the Invention is to solve]

When a coupling Is used as a joint element, an electro platlng layer Is formed on a surface of a female screw carved on an Inner drcumferential surface ofthe coupling, and thus, reliability (selzure résistance) of a Joint portion Is improved. Also In an Intégral Joint, In order to obtain the similar reliability, lt 1s préférable that an electro plating layer be formed on a surface of a

- 2 17188 female screw (box) carvad on an Inner drcumferentlal surface of one pipe end of an oil-well pipe.

In general, when the electro plating layer is formed, bubbles of hydrogen or oxygen are generated concurrently with the electro plating layer. As described In Patent Document 1, when the electro plating layer is formed on the surface of the male screw carved on the outer circumferential surface ofthe steei pipe, sînce bubbles are rapîdly separated from the surface of the maie screw, there ls no problem. However, when the electro plating layer ls formed on the surface ofthefemalescrewcarved on the Innercircumferential surface ofthe steelpipe, slnce séparation of the bubbles ls Impeded due to an inner wall of the steel pipe, particularly, the bubbles easily remain In grooves of the female screw. The resldual portion of the bubbles becomes an unpiated région and becomes the cause which decreases selzure résistance of the joint portion.

The présent Invention ls made In considération ofthe above-described drcumstance, and an object thereof is to provide an electro plating device capable of forming a unlform electro plating layer wlthout an unpiated région on the surface of the female screw carved on the Inner circumferential surface of the pipe end ofthe steel pipe.

[Means for Solving the Problems]

The présent invention adopts the following means in order to solve the above-described problems and achieve the related object That is, (1 ) According to an aspect of the présent invention, there is provided an electro plating device which forms an electro plating layer on a surface of a female screw carved on an Inner drcumferentlal surface of a pipe end of a steel pipe, including: a pipe inside seal mechanism which ocdudes an Inner channel of the steel pipe at a position distanced from the female screw in a pipe

- 3 17188 axial direction of the steel pipe; a tubular insoluble electrode which Is disposed in the pipe end so as to be opposite to the female screw; a plating solution feed mechanism which indudes a piurality of nozzles which extend radtaliy with a pipe axis ofthe steei pipe as a center and is disposed outside the pipe end; and a pipe end seal mechanism which accommodâtes the nozzles thereinslde and is mounted to the pipe end In a state where the pipe end seal mechanism dosely contacts an outer drcumferential surface ofthe pipe end, and when viewed In the pipe axial direction, a tip of each of the nozzles is positioned between the female screw and the insoluble eiectrode, and each of the nozzles injects the platlng solution from an Injection port formed on the tip toward a direction which Intersects an extension direction ofthe nozzle, the direction being a rotational direction of a dockwise direction or a counterclockwise direction in which the pipe axis Is the center.

(2) In the electro platlng device according to (1), each of the nozzles may be perpendicular to the pipe axial direction or be Indined toward the pipe end side.

(3) In the electro platlng device according to (1 ), each of the nozzles may be perpendicular to the pipe axial direction, and each of the nozzles may inject the platlng solution In a reference direction perpendicular to the pipe axial direction and the extension direction when viewed In the extension direction of the nozzle or Inject the plating solution in a direction which is Indined from the reference direction to the pipe end side.

(4) In the electro plating device according to any one of (1) to (3), the plating solution feed mechanism may Indude three nozzles.

(5) In the electro plating device according to any one of (1 ) to (4), the pipe end seal mechanism may further include: a discharglng port for discharging a used plating solution; and a liquid discharge promotion mechanism for promotlng discharglng ofthe used plating solution.

- 4 17188 (6) In the electro plating device according to (5), the liquid discharge promotion mechanism may be an atmosphère opening portion which Is dlsposed at a position above the steel pipe In the pipe end seal mechanism.

[Effects of the Invention]

According to the above-described aspects, a uniform electro plating layer can be formed without an unplated région on the surface of the female screw carved on the Inner drcumferentla! surface of the pipe end of the steel pipe.

[Brlef Description of the Drawing]

FIG 1 Is an expianatory view conceptually showing a configuration of an electro plating device according to an embodiment of the présent invention.

FIG 2 is a cross-section view taken along Une A-Aof FIG 1 (a view when viewed In a pipe axial direction of a steel pipe 0).

FIG 3 Is a view when a plating solution feed mechanism 7 In modification example Is viewed in a direction perpendicular to the pipe axial direction of the steel pipe 0.

FIG 4 Is a cross-section view taken along line B-B of FIG 3 (a view when viewed In a pipe axial direction of a steel pipe 0).

FIG 5 is a view when a plating solution Injection nozzle 7a Is viewed in an extension direction R11 thereof.

[Best Mode for Carrying Out the Invention]

Herelnafter, an embodiment of the présent Invention will be described In detail with référencé to drawings or the like.

- 5 17188

FIG 1 is an explanatory view conceptually showing a configuration of an eiectro plating device 1 according to an embodiment of the présent Invention.

As shown in FIG 1, the eiectro plating device 1 according to the présent embodiment Is a device which forms an eiectro plating layer on a surface of a female screw 0b spirally carved on an Inner drcumferential surface of one pipe end 0a of a cylindrical steel pipe 0. In FIG 1, a state where the steel pipe 0 Is disposed approximately horizontally Is exemplified. In descriptions below, a case where the steel pipe 0 Is a long seamless oil-well pipe 1s exemplified. Moreover, a référencé numéral AX in the drawing Indicates a pipe axis (central axis) of the steel pipe 0.

The eiectro plating device 11ncludes a pipe Inside seal mechanism 2, a pipe end seal mechanism 3, an Insoluble eiectrode 4, and a plating solution feed mechanism 5. Hereinafter, the details of each component of the eiectro plating device 1 will be described sequentially.

[Pipe Inside Seal Mechanism 2]

The pipe inside seal mechanism 2 Is disposed at a predetermlned position Oc inside In a pipe axial direction (a direction along the pipe axis AX In FIG 1) of the steel pipe 0 from a female screw Ob of the steel pipe 0. The pipe Inside seal mechanism 2 contacts the steel pipe 0 In a sealing state at the predetermined position Oc. In other words, the pipe Inside seal mechanism 2 occludes an inner channel of the steel pipe 0 at the predetermlned position Oc.

For example, as the pipe inside seal mechanism 2, a hex plug which is used In piping work may be used. As Is well known, the hex plug has a structure which occludes an Inner channel of a tubular member by inserting a ru b ber ring between two plates and expanding the diameter of the rubber ring. Moreover, the pipe Inside seal mechanism 2 is not limited to the hex plug and may be any device if having a structure capable of ocduding the Inner channel of the

- 6 17188 steel pipe 0.

Since the pipe inside seal mechanism 2 Is well known by a person skilled in the art, further descriptions with respect to the pipe inside seal mechanism 2 are omitted.

IPipe End Seal Mechanism 3]

The pipe end seal mechanism 3 inciudes a tubular main body 3a which accommodâtes plating solution injection nozzles 5a, 5b, and 5c included in the plating solution feed mechanism 5 described below thereinside and inciudes an inner surface shape which can be mounted in a state where the main body 3a ciosely contacts an outer circumferential surface and an end surface of the pipe end 0a of the steel pipe 0.

The pipe end seal mechanism 3 is mounted to the pipe end 0a In the state where the main body 3a ciosely contacts the outer drcumferential surface and the end surface of the pipe end 0a of the steel pipe 0, and thus, the pipe end seal mechanism 3 seals the inside of the pipe end 0a of the steel pipe 0 along with the pipe inside seal mechanism 2.

A liquid discharge port 3c and a iiquid discharge promotion mechanism 3b are disposed in the main body 3a of the pipe end seal mechanism 3.

The liquid discharge port 3c discharges plating solution after the plating solution is used for formation of the electro plating layer, and is disposed at a position lower than the steel pipe 0 when the pipe end seal mechanism 3 is mounted to the steel pipe 0.

The liquid discharge promotion mechanism 3b promûtes discharging of used plating solution. The liquid discharge promotion mechanism 3b Is not limited to a spécifie type if it can promote the discharging of the plating solution, and as shown in FIG 1, is preferably an atmosphère opening port 3b which is disposed at a position above the steel pipe 0 In the pipe end

- 7 17188 seal mechanism 3.

A configuration may be adopted in which an eiectromagnetic valve (not shown) is disposed at the atmosphère opening port 3b and the atmosphère opening port 3b Is opened and closed. Aitematively, a hose Is mounted to the atmosphère opening port 3b, the hose Is extended upward, and It may prevent the liquid from being blown outside the main body 3a by balancing pressure of liquid inserted by a pump and the weight of the liquid itself. Aitematively, the discharging of the used plating solution may be promoted by feeding compressed air from the atmosphère opening port 3b to the Inner portion of the pipe end 0a, or the like.

If the used plating solution is not rapidly discharged after the eiectro plating layer Is formed, the eiectro plating layer may corrode and color of the layer may be changed. However, as described above, since the atmosphère opening port 3b Is provided In the pipe end seal mechanism 3 and thus, the used plating solution Is rapidly discharged, the change of color of the surface of the eiectro plating layer formed on the female screw 0b can be suppressed.

[Insoluble Electrode 4]

The Insoluble electrode 4 is a hollow cylindrical electrode (anode) for formlng the eiectro plating layer on the female screw 0b and Is disposed In the pipe end 0a of the steel pipe 0 so as to be opposite to the female screw 0b. It Is préférable that the central axis of the Insoluble electrode 4 be disposed so as to coïncide with the pipe axis AX of the steel pipe 0. That Is, when viewed In the pipe axial direction of the steei pipe 0, It Is préférable that the steel pipe 0 and the Insoluble electrode 4 hâve a concentric relationship. The Insoluble electrode 4 Is disposed In thls way, and thus, an eiectro plating layer having high uniformlty can be formed on the surface of the female screw 0b which Is carved on the Inner drcumferentiai surface of the pipe end 0a.

- 8 17188

As the insoluble electrode 4, It is préférable that an electrode, in which an iridium oxide coating titanium plate or stainless steel plate, or the like Is formed In a cylindricai shape, be used.

An energizing bar 6 for energizing the insoluble electrode 4 pénétrâtes the main body 3a of the pipe end seai mechanism 3 and is connected to the insoluble electrode 4. For example, a titanium bar, a stainless steel bar, or the like may be used as the energizing bar 6.

If a potential différence is applied between the insoluble electrode 4 and the steel pipe 0 while the piating solution is supplied between the female screw 0b and the Insoluble electrode 4 by the platlng solution feed mechanism 5 described beiow, the electro piating layer is formed on the surface of the female screw Ob.

Since the insoluble electrode 4 is well known by a person skiiled In the art, further descriptions with respect to the insoluble electrode 4 are omitted.

[Piating Solution Feed Mechanism 5]

The piating solution feed mechanism 5 supplies the platlng solution to the inside of the pipe end Oa of the steel pipe 0 and Is supported at a position outside the pipe end Oa by a supportlng mechanism (not shown) which Is provided on the pipe end seal mechanism 3.

Hereinafter, a configuration of the piating solution feed mechanism 5 wili be described in detail with référencé to FIGS. 1 and 2. Moreover, FIG 2 Is a cross-section view taken along line A-A of FIG 1 (that Is, a view when Is vlewed outside of the steel pipe 0 from Inside of the steel pipe 0 In the pipe axial direction of the steel pipe 0).

As shown In FIGS. 1 and 2, the platlng solution feed mechanism 5 Includes a plurality of (three as an example In the présent embodiment) piating solution Injection nozzles 5a, 5b, and 5c which extend radially with the pipe axis AX of the steel pipe 0 as the center. As shown in FIG 2,

- 9 17188 when viewed in the pipe axial direction of the steel pipe 0, tips (refer to référencé numerals 5a-1, 5b-1, and 5o-1 in FIG 2) ofthe respective piating solution Injection nozzles 5a, 5b, and 5c are disposed between the female screw 0b and the insoluble electrode 4.

In addition, when viewed in the pipe axial direction ofthe steel pipe 0, the respective piating solution injection nozzles 5a, 5b, and 5c Inject the piating solution from Injection ports (refer to référencé numerals 5d, 5e, and 5f in FIG 2) formed on each tip ofthe nozzles toward directions which intersect extension directions (refer to référencé numerals R1, R2, and R3 in FIG 2) ofthe piating solution Injection nozzles, the directions being rotational directions of a clockwise direction or a counterclockwise direction In which the pipe axis AX is the center. Hereinafter, the directions In which the piating solution is Injected from the respective piating solution injection nozzles 5a, 5b, and 5c are referred to as piating solution Injection directions (refer to référencé numerals S1, S2, and S3 In FIG 2).

Moreover, as described above, the respective piating solution injection directions S1, S2, and S3 may be set to the rotational direction of any one of the clockwise direction and the counterclockwise direction In which the pipe axis AX is the center. However, in order to suppress the occurrence of the unpiated régions effectively, it is préférable that the respective piating solution Injection directions S1, S2, and S3 are set to the same rotational direction of the clockwise direction or the counterclockwise direction as a screw cutting direction ofthe femaie screw 0b.

As shown in FiG 2, the extension direction R1 of the piating solution Injection nozzle 5a intersects the piating solution Injection direction S1. However, both (R1 and S1 ) do not necessarily intersect each other In a state where both are perpendicular to each other. In other words, an Intersection angle between the extension direction R1 ofthe piating solution Injection nozzle 5a and the piating solution injection direction S1 Is not limited to 90°, and may be

- 10 17188 appropriately set according to the dimensions of the steel pipe 0 and the Insoluble electrode 4 or the like so that a unifonm electro plating layer ls formed on the surface of the female screw 0b.

A relationship between the extension direction R2 of the plating solution Injection nozzle 5b and the plating solution injection direction S2 and a relationship between the extension direction R3 of the plating solution injection nozzle 5c and the plating solution Injection direction S3 are similar to the above.

In addition, for example, when the screw cutting direction of the female screw 0b ls the clockwise direction, It is préférable that ail of the plating solution Injection directions S1, S2, and S3 are set so as to face the rotational direction of the clocwise direction in which the pipe axis AX ls the center.

Moreover, an angle between adjacent plating solution Injection nozzles may be appropriately set according to the total number of the plating solution Injection nozzles. For example, In the présent embodiment, when the total number of the plating solution injection nozzles ls 3, the angle between the adjacent plating solution injection nozzles may be setto 120°.

In addition, as shown in FIG 1, when viewed in the direction perpendicular to the pipe axial direction of the steel pipe 0, the respective plating solution Injection nozzles 5a, 5b, and 5c are Inclined toward the pipe end 0a side. In order words, the extension directions R1, R2, and R3 of the respective plating solution Injection nozzles 5a, 5b, and 5c are Inclined with respect to the pipe axis AX of the steel pipe 0.

For example, It ls préférable that an Inclined angle (référencé numéral a1 in FIG 1) between the plating solution injection nozzle 5a (extension direction R1) and the pipe axis AX be appropriately set according to the dimensions of the steel pipe 0 and the Insoluble electrode 4 or

- 11 17188 the like so that a uniform electro plating layer is formed on the surface of the female screw 0b. According to examination conducted by the Inventors, it was established that the electro plating layer having high uniformity was formed if the Inclined angle a1 was set to a range equal to or more than 45° and less than 90°.

Moreover, the plating solution Injection nozzle 5a (extension direction R1) may be perpendicular to the pipe axial direction of the steel pipe 0 (that is, inclined angle a1 = 90°). Also in this case, it was established that the electro plating layer having high uniformity was formed.

A relationship between the plating solution Injection nozzle 5b and the pipe axis AX and a relationship between the plating solution injection nozzle 5c and the pipe axis AX are simiiar to the above.

According to the electro plating device 1 of the présent embodiment described above, the uniform electro plating layer can be formed without an unplated région on the surface of the female screw 0b carved on the Inner drcumferential surface of the pipe end 0a of the steel pipe 0. Hereinafter, the reasons will be described.

When the electro plating layer Is formed on the screw surface of the steel pipe 0, a method which séparâtes bubbles by applying a jet of the plating solution is generally known. For example, In the related art disclosed in Patent Document 1, it is possible to apply the jet of the plating solution by increasing a supply amount of the plating solution.

However, the plating surface is a surface of a screw and includes thread ridges and thread bottoms. Thereby, the jet Is weak at thread bottoms while the jet is strong near the surfaces of thread ridges. Since hydrogen gas or oxygen gas generated when the electro plating layer Is formed are minute bubbles, the bubbles accumulated In the thread bottoms are not

- 12 17188 separated from the thread bottoms untii the minute bubbles are collected In the thread bottoms (grooves of the screw) and become large bubbles. The unplated région which really occurs Is a small dot-like région. Moreover, the screw which Is used for fastening members Is formed In a three-dimenslonal spiral shape.

As the method which séparâtes minute bubbles from thread bottoms, the Inventors found a method which feeds the plating solution by a spiral jet between the surface of the female screw 0b and the insoluble electrode 4 by a plurality of, that is, two or more plating solution Injection nozzles. However, when a single plating solution injection nozzle is used, sufficient jet effects cannot be obtained.

Moreover, even when three plating solution injection nozzles are installée! on the tips of the supply port, if the plating solution injection direction of each plating solution Injection nozzie is not appropriate, a pressure balance between the plating solution injection nozzles cannot be appropriately adjusted, and sufficient jet effects cannot be obtained.

Therefore, the plurality of plating solution Injection nozzles are disposed at the supply port of the center of the pipe end 0a of the steel pipe 0, and a uniform spiral jet can be obtained by adjusting the plating solution injection directions of each of the plating solution injection nozzles.

Spedfically, as shown In FIGS. 1 and 2, the tips of the respective plating solution injection nozzles 5a, 5b, and 5c are incllned to the pipe axis AX of the steel pipe 0 to be plated. It is préférable that three or more plating solution Injection nozzles be provided. Moreover, it is préférable that the plating solution injection directions S1, S2, and S3 of the plating solution injection nozzles 5a, 5b, and 5c be set so that the spiral jet is formed In the same rotational direction as the screw cutting direction of the surface of the female screw 0b to be plated.

- 13 17188

It Is préférable that tips of the respective plating solution Injection nozzles 5a, 5b, and 5c be positioned at the outside of the steel pipe 0 from the tip of the female screw Ob, that Is, a tip Oa1 of the pipe end Oa of the steel pipe 0 so that bubbles are separated from the entire région of the surface of the female screw Ob.

Moreover, It Is préférable that the tip surfaces of respective plating solution Injection nozzles 5a, 5b, and 5c be positioned between the female screw Ob and the Insoluble electrode 4 In a radial direction of the steel pipe 0.

The tips of the respective plating solution injection nozzies 5a, 5b, and 5c are lineariy formed toward the female screw Ob. However, for example, a portion of the tip Including the tip 10 surface of each of the plating solution Injection nozzles 5a, 5b, and 5c may be Inclined toward the outside in the radial direction of the steel pipe 0 according to the diameter of the steel pipe 0, the dimensions of the female screw Ob, or the like In order to Increase unîformîty of the spiral jet which Is formed between the female screw Ob and the Insoluble electrode 4. In addition, even in the case where a portion of the tip Including the tip surface of each of the plating solution Injection 15 nozzles 5a, 5b, and 5c Is not inclined toward the outside In the radial direction of the steel pipe 0, when the steel pipe 0 which is electro-piated is changed, It Is préférable that orientation directions (plating solution Injection directions) of the respective plating solution Injection nozzies 5a, 5b, and 5c be appropriately corrected according to the diameter of the steel pipe 0, the dimensions of the female screw 0b, or the like.

As described above, In the electro plating device 1 of the présent embodiment, slnce a uniform spiral jet can be formed between the female screw 0b and the Insoluble electrode 4, the bubbles remalnlng on the thread bottoms of the female screw 0b can be effectively removed.

Therefore, according to the electro plating device 1 of the présent embodiment, the

- 14 17188 uniform electro platîng layer can be formed without an unplated région on the surface of the female screw 0b carved on the Inner circumferential surface of the pipe end 0a of the steel pipe 0.

In addition, according to the electro platîng device 1 of the présent embodiment, since the atmosphère opening port 3b is provided in the pipe end seal mechanism 3 and thus, the used platîng solution is rapidly discharged, the change of color of the surface of the electro plating layer formed on the female screw 0b can be suppressed.

Moreover, the présent invention is not limited to the above-described embodiment, and there may be modification example beiow. For example, Instead of the plating solution feed mechanism 5 shown in FIGS. 1 and 2, a plating solution feed mechanism 7 including a configuration shown In FIGS. 3 and 4 may be used. FIG 3 Is a view when the plating solution feed mechanism 7 in Modification Example is viewed In a direction perpendicular to the pipe axial direction of the steel pipe 0. FIG 4 is a cross-section view taken along fine B-B of FIG 3 (that is, a view when is viewed outside of the steel pipe 0 from inside of the steel pipe 0 in a pipe axial direction of a steel pipe 0).

As shown in FIGS. 3 and 4, the plating solution feed mechanism 7 of Modification Example includes a plurality of (three as an example in the présent embodiment) plating solution injection nozzles 7a, 7b, and 7c which extend radially with the pipe axis AX of the steel pipe 0 as the center. As shown In FIG 4, when viewed In the pipe axiai direction of the steel pipe 0, tips (refer to référencé numerals 7a-1,7b-1, and 7c-1 in FIG 4) of the respective plating solution Injection nozzles 7a, 7b, and 7c are disposed between the female screw 0b and the insoluble electrode 4.

in addition, when viewed in the pipe axial direction of the steel pipe 0, the respective piating solution Injection nozzles 7a, 7b, and 7c Inject the plating solution from Injection ports (refer

- 15 17188 to référencé numérale 7d, 7e, and 7f In FIG4) formed on each tip of the nozzles toward directions which intersect extension directions (refer to référencé numerals R11, R12, and R13 in FIG 4) of the plating solution injection nozzles, the directions being rotational directions of the clockwise direction or the counterclockwise direction in which the pipe axis AX is the center. Hereinafter, the directions in which the plating solution is injected from the respective plating solution injection nozzles 7a, 7b, and 7c are referred to as plating solution injection directions (refer to référencé numerals S11, S12, and S13 in FIG4).

Moreover, as described above, the respective plating solution injection directions S11, S12, and S13 maybe settothe rotational direction ofanyone ofthe clockwisedirectionandthe counterclockwise direction in which the pipe axis AX is the center. However, In order to suppress the occurrence ofthe unplated régions effectlvely, it is préférablethatthe respective plating solution injection directions S11, S12, and S13 are set to the same rotational direction ofthe clockwise direction or the counterclockwise direction as the screw cutting direction of the female screw 0b.

As shown In FIG 4, the extension direction R11 of the plating solution injection nozzle 7a intersects the plating solution Injection direction S11. However, both (R11 and S11) do not necessarily Intersect each other in a state where both are perpendicuiar to each other. In other words, an intersection angle between the extension direction R11 of the plating solution Injection nozzle 7a and the plating solution injection direction S11 is not limited to 90°, and may be appropriately set according to the dimensions of the steel pipe 0 and the insoluble eiectrode 4 or the like so that a uniform electro plating iayer is formed on the surface ofthe femaie screw 0b.

A reiationship between the extension direction R12 of the plating solution Injection nozzle 7b and the plating solution injection direction S12 and a reiationship between the extension

- 16 17188 direction R13 of the plating solution Injection nozzle 7c and the plating solution injection direction S13 are similar to the above.

In addition, for example, when the screw cutting direction of the female screw 0b Is the right-handed rotation, It is préférable that ali ofthe plating solution Injection directions S11, S12, and S13 are set so as to face the rotational direction of the clockwise direction In which the pipe axis AXis the center.

Moreover, an angle between adjacent plating solution Injection nozzles may be appropriately set according to the total number of the plating solution Injection nozzles. As shown in FIG 4, when the total number of the plating solution Injection nozzles is 3, the angle between the adjacent plating solution injection nozzles may be set to 120°.

In addition, as shown In FIG 3, when viewed in the direction perpendicuiar to the pipe axial direction of the steel pipe 0, the respective plating solution Injection nozzles 7a, 7b, and 7c are perpendicuiar to the pipe axial direction of the steel pipe 0. In other words, the extension directions R11, R12, and R13 ofthe respective plating solution injection nozzles 7a, 7b, and 7care perpendicuiar to the pipe axial direction of the steel pipe 0.

in addition, for example, as shown In FIG 5, when viewed In the extension direction R11 of the plating solution Injection nozzle 7a, the plating solution injection nozzle 7a injects the plating solution toward the direction which Is inclined from a reference direction V perpendicuiar to the pipe axial direction and the extension direction R11 to the pipe end 0a slde.

That Is, when viewed in the extension direction R11 of the plating solution Injection nozzle 7a, the plating solution Injection direction S11 of the plating solution Injection nozzle 7a Is Inclined from the reference direction V to the pipe end 0a slde.

- 17 17188

It Is préférable that an Inclined angle (référencé numéral a2 In FIG5) between the plating solution Injection direction S11 of the plating solution Injection nozzle 7a and the référencé direction V be appropriately set according to the dimensions of the steel pipe 0 and the Insoluble electrode 4 or the like so that a uniform electro plating layer Is formed on the surface of the female 5 screw Ob. According to examination conducted by the Inventors, It was established that uniform electro plating layer was formed without an unplated région If the Indined angle a2 was set to a range more than 0° and less than or equal to 45° (more preferably, a range more than 0° and less than or equal to 20°).

In addition, the plating solution injection nozzle 7a may injed the plating solution in the référencé direction V. In this case, the plating solution injection direction S11 of the plating solution Injection nozzle 7a and the référencé direction V coindde with each other (that Is, the inclined angle a2= 0°). Also In this case, it was established that the electro plating iayer having high uniformity was formed. The plating solution Injection nozzles 7b and 7c are also similar to the above.

[Exemple]

Herelnafter, Exampies of the présent Invention will be described.

A degreaslng liquid (sodium hydroxide - 50 g/L), a Ni-strike bath (nickel chloride = 250 g/L and hydrochloric acid = 80 g/L), and a copper plating bath (copper sulfate - 250 g/L and suifuric add = 110 g/L) were prepared, and copper plating was performed by processes and 20 conditions shown in Table 1 using the electro plating device 1 shown In FIG 1.

[Table 1] ’rocess

Cathode Electrolytic Degreasing

Ni-Strike

Copper plating

- 18 17188

'reatme nt îonditio n	Bath Température (°C)	Current Density (A/dm2)	Treatment Time (second)	Bath Température (°C)	Current Density (A/dm2)	Treatment Rme (second)	Bath Température (°C)	Current Density (A/dm2)	Treatment Time (second)
50	6	60	35	6	120	50	8	400

By changing the ptating solution injection nozzle type, the number of the plating solution

Injection nozzles, and the presence or absence of the atmosphère openlng port, the presence or absence of an unplated région (Good: None, Normal: Slight Occurrence, and Bad: Large Occurrence) and the presence or absence of the change of the color of the plated surface (Good:

Absence and Bad: Presence) were examined. Results are shown in Table 2. In addition, in a column of a “nozzle type* of Table 2, a separated type outside the pipe means a type (Comparatives 1 and 2) In which the plating solution Injection nozzles are fixed to the main body of the pipe end seai mechanism indivldually and supplied the plating solution from the outside of the pipe via hoses Indivldually. Additionally, In a column of a “nozzle type* of Table 2, a common type Inside the pipe means a type (Examples 1, 2, and 3) which uses the disposition of the plating solution Injection nozzle shown in FIG 1.

[Table 2]

Classification	Nozzle Type	Number of Nozzle	Upper Portion Atmosphère Opening Port	Unplating	Change of Color of Surface
Comparative Example 1	Separated Type Outside Pipe	1	Absence	Bad	Bad
Comparative	Separated Type	3	Absence	Bad	Bad

- 19 17188

Example 2	Outslde Pipe
Example 1	Common Type Inslde Pipe	3	Presence	Good	Good
Example 2	Common Type Inslde Pipe	4	Presence	Good	Good
Example 3	Common Type Inslde Pipe	2	Presence	Normal	Good

As shown In FIG 2, when the plating solution injection nozzle was Individually provided o ut si de the pipe (Comparative Examples 1 and 2), even though the number of the plating solution Injection nozzles was 3, a uniform spiral jet could not be obtained, and unplated réglons occurred.

On the other hand, when three or more plating solution injection nozzles were provided in common Inslde the pipe (Examples 1 and 2), It was understood that the unplated région dîd not occur. This was consldered because bubbles remalning on the thread bottoms of the female screw were effectively removed by forming a uniform spiral jet between the female screw and the anode of the insoluble electrode.

In addition, It was confirmed that the plating solution was rapidly discharged by providing the atmosphère opening port at the position of the upper portion of the pipe and the change of the coior of the surface of the electro plating layer did not occur.

Moreover, It was found that although the unplated régions slightly occurred In Exampie 3 (when the number of plating solution injection nozzles were two) of Table 2, it was levei without problems, and removal effects of the bubbles were suffident

As understood from the results, In order to prevent the unplated réglons from occumng due to the staying of the oxygen gas generated from the anode at the time of plating, the method

- 20 17188 applying the jet is consldered. it Is effective in a case of a fiat shape only by providing the plating solution injection nozzle outslde the pipe. However, in the spiral screw shape, bubbles stay on the thread bottoms and unplated régions occur. Even when the number of the plating solution injection nozzles is increased, a uniform jet is not obtained, and the unplated régions occur.

On the other hand, if the plurality of, that is, two or more plating solution injection nozzles are provided in common inside the pipe, a uniform spiral jet can be formed between the femaie screw and the insoluble electrode, remaining bubbles on the thread bottoms are effectîvely removed, and occurrence of the unplated régions can be prevented. The number of the plating solution injection nozzles is preferably3, and thus, occurrence ofthe unplated régions can be securely prevented. In addition, the plating solution is rapidly discharged by providing the atmosphère opening port, and the change of the coior of the surface of the plated femaie screw does not occur.

[Description of Reference Numerals and Signs]

0: steel pipe

Oa: pipe end

Oa-1 : tip of pipe end

Ob: female screw

Oc: predetermined position : electro platlng device

2: pipe inside seal mechanlsm

3: pipe end seal mechanism

- 21 17188

3a: main body

3b: liquid discharge promotion mechanism (atmosphère opening port)

3c: liquid discharge port

4: Insoluble electrode

5 and 7: plating solution feed mechanism

5a, 5b, and 5c: plating solution injection nozzle

7a, 7b, and 7c: piating solution injection nozzle

5a-1,5b-1, and 5c-1: tip of plating solution éjection nozzle

7a-1,7b-1,7o-1: tip of plating solution Injection nozzle

6: energlzing bar

- 22 17188

Claims (1)

1. [Type of Document] CLAIMS [Claim 1]

   An electro plating device which forms an electro plating layer on a surface of a female screw carved on an inner drcumferential surface of a pipe end of a steel pipe, the electro plating device comprising:

   a pipe inside seal mechanism which occludes an inner channel of the steel pipe at a position distanced from the female screw in a pipe axial direction of the steel pipe;

   a tubular insoluble electrode which Is disposed in the pipe end so as to be opposite to the female screw;

   a plating solution feed mechanism which includes a plurality of nozzles which extend radlally with a pipe axis of the steel pipe as a center, and is disposed outside the pipe end; and a pipe end seai mechanism which accommodâtes the nozzles theretnstde and is mounted to the pipe end In a state where the pipe end seal mechanism closely contacts an outer drcumferential surface of the pipe end, wherein when viewed in the pipe axial direction, a tip of each of the nozzles Is posltioned between the female screw and the Insoluble electrode, and each of the nozzles injects the plating solution from an Injection port formed on the tip toward a direction which intersects an extension direction of the nozzle, the direction being a rotational direction of a dockwise direction or a counterdockwise direction in which the pipe axis is the center.

   - 23 17188 (Claim 2]

   The electro plating device according to daim 1, wherein each of the nozzles 1s perpendicular to the pipe axial direction or Is Indined toward the pipe end side.

   5 [Claim 3]

   The electro plating device according to daim 1, wherein each of the nozzles is perpendicular to the pipe axial direction, and each of the nozzles injects the plating solution In a reference direction perpendicular to the pipe axial direction and the extension direction when viewed In the extension direction of the nozzle or Injeds the

   10 plating solution In a direction which Is Indined from the reference direction to the pipe end side.

   [Claim 4]

   The electro plating device according to any one of daims 1 to 3, wherein the plating solution feed mechanism Indudes three nozzles.

   [Claim 5]

   15 · The electro plating device according to any one of daims 1 to 4, wherein the pipe end seal mechanism further indudes:

   a discharglng port for discharglng a used plating solution; and a liquid discharge promotion mechanism for promoting discharging of the used plating solution.

   - 24 17188 [Claim 6]

   The electro plating device according to claim 5, wherein the liquid discharge promotion mechanism ls an atmosphère openlng portion which ls disposed at a position above the steel pipe in the pipe end seal mechanism.