SPECIFICATION
[Title of the Invention] ELECTRO PLATING DEVICE
[Technical Field]
[OOOl]
The present invention relates to an electro plating device which forms an
electro plating layer on a surface of a female screw carved on an inner circumferential
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 reference.
[Background Art]
[0002]
In order to collect natural gas or crude oil from underground, a pit is dug
toward a natural gas field or an oil 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 tlie viewpoint of productivity
impmvenient, a need for a screw joint (so-called integral joint) for a steel pipe capable
of directly connecting tlie oil-well pipes without using a coupling is increasing. The
oil-well pipe having a male screw formed on an outer circumferential surface of one
pipe end and a female screw formed on an inner circumferential surface of the other
pipe end is used as the integral joint. That is, the integral joint includes the male
screw @in) w11ich is spirally calved on the outer circumferential surface of one pipe
end of the oil-well pipe, and the female screw (box) which is spirally carved on the
inner circumferential surface of one pipe end of the other oil-well pipe connected to the
oil-well pipe.
[0003]
Conventionally, when the oil-well pipes are secured to each other, in order to
prevent seizure of the joint portion, lubricating oil (API dope) including 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 region in which use of the API dope is limited
under a severe environmental regulation, enviromient protective lubricating oil (green
dope) not including heavy metals may be used. Since lubricity of the green dope is
worse than that of the API dope, the seizure easily occurs in the joint portion.
Thereby, wvlien the green dope is used as the lubricating oil, in order to compensate for
lack of the lubricity of the green dope and prevent occurrence of the seizure, it is
preferable that an electro plating 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.
[0004]
For example, in Patent Document 1 below, a device is disclosed which forms
an electro plating layer on a surface of a male screw bin) carved on one pipe end of
the oil-well pipe, that is, on an outer circumferential surface of one pipe end of the oilwell
pipe.
[Prior Art Document]
[Patent Document]
[OOOS]
[Patent Document I] Japanese Examined Patent Application, Second
Publication No. S63-6637
[Disclosure of the Invention]
[Problem that the Inventiol is to solve]
[0006]
When a coupling is used as a joint element, aa electro plating layer is formed
on a surface of a female screw carved on an inner circumferential surface of the
coupling, and thus, reliability (seizure resistance) of a joint portiol is improved. Also
in an integral joint, in order to obtain the similar reliability, it is preferable that an
electro plating layer be formed on a surface of a female screw (box) cawed on an inner
circumferential surface of one pipe end of an oil-well pipe.
[0007]
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 of the steel pipe, since bubbles are
rapidly separated from the surface of the male screw, there is no problem. However,
when the electro plating layer is formed on the surface of the female screw carved 011
the inner circumferential surface of the steel pipe, since separation of the bubbles is
impeded due to an inner wall of the steel pipe, particularly, the bubbles easily remain
in grooves of the female screw. The residual portion of the bubbles becomes an
unplated region and becomes the cause which decreases seizure resistance of the joint
portion.
[OOOS]
The present invention is made in consideration of the above-described
circumstance, and an object thereof is to provide an electro plating device capable of
forming a uniform electro plating layer without an unplated region on the surface of
the female screw carved on the inner circumtlferentia surface of the pipe end of the
steel pipe.
[Means for Solving the Problems]
The present invention adopts the following means in order to solve the abovedescribed
problems and achieve the related object. That is,
(1) According to an aspect of the present 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 circumferential surface of a pipe end of a steel pipe,
including: 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 radially with a pipe axis of the steel pipe as a center
and is disposed outside the pipe end; and a pipe end seal mechanism which
accotnmodates the nozzles thereinside and is mounted to the pipe end in a state where
the pipe end seal nlechanis~nc losely contacts an outer circumferential surface of the
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 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 clockwise direction or a counterclock wise direction in which
the pipe axis is the center,
[OO 1 01
(2) In the electro plating device according to (I), each of the nozzles may be
perpendicular to the pipe axial direction or be inclined toward the pipe end side.
[OOll]
(3) In the electro plating device according to (I), each of the nozzles may be
perpendicular to the pipe axial direction, and each of the nozzles may inject 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 inject the
plating solution in a direction which is inclined from the reference direction to the pipe
end side.
[OO 121
(4) In the electro plating device according to any one of (1) to (3), the
plating solution feed mechanism may include three nozzles.
[0013]
(5) In the electro plating device according to any one of (1) to (4), the pipe
end seal mechanism may further include: a discharging port for discharging a used
plating solution; and a liquid discharge promotion mechanism for promoting
discharging of the used plating solution.
[0014]
(6) In the electro plating device according to (5), the liquid discharge
pro~notionm echanism may be an atmosphere opening portion which is disposed at a
position above the steel pipe in the pipe end seal mechanism.
[Effects of the Invention]
[0015]
According to the above-described aspects, a uniform electro plating layer can
be formed without an unplated region on the surface of the female screw carved 011 the
inner circumferential surface of the pipe end of the steel pipe.
[Brief Description of the Drawillg]
[0016]
FIG. 1 is an explanatory view conceptually showing a configuration of an
electro plating device according to an enlbodi~nenot f the present invention.
FIG. 2 is a cross-section view taken along line A-A of FIG. 1 (a view when
viewed it1 a pipe axial direction of a steel pipe 0).
FIG. 3 is a view when a plating solotion feed mechanism 7 in nlodification
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]
[0017]
Hereinafter, an enlbodiment of the present invention will be described in
detail with reference to drawings or the like.
FIG. 1 is an explanatory view conceptually showing a configmation of an
electro plating device 1 according to an embodiment of the present invention.
[0018]
As shown in FIG. 1, the electro plating device I according to the present
embodin~enits a device which forrns an electro plating layer on a surface of a female
screw Ob spirally carved on an inner circumferential surface of one pipe end Oa 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 \vhere the
steel pipe 0 is a long seamless oil-well pipe is exemplified. Moreover, a reference
numeral AX in the d~awingin dicates a pipe axis (central axis) of the steel pipe 0.
[00 191
The electro plating device 1 includes a pipe inside seal mechanism 2, a pipe
end seal mechanism 3, an insoluble electrode 4, and a plating solution feed mechanisln
5. Hereinafter, the details of each component of tile electro plating device 1 will be
described seque~ltially.
[0020]
[Pipe Inside Seal Mechanism 21
The pipe inside seal mechanism 2 is disposed at a predetermined position Oc
illside 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 predetermined position Oc.
[0021]
For example, as the pipe inside seal nlechanisln 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 inse~?inga lubber 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 occluding the inner channel of the steel pipe 0.
[0022]
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.
[0023]
[Pipe End Seal Mechanism 3 j
The pipe end seal mechanisnl3 includes a tubular main body 3a w11ich
accon~modatesp lating solution injection nozzles 5a, 5b, and 5c included in the plating
solution feed mechanism 5 described below thereinside and includes an inner surface
shape which can be mounted in a state where the main body 3a closely contacts an
outer circumferential surface and an end surface of the pipe end Oa of the steel pipe 0.
[0024]
The pipe end seal n~echanism3 is mounted to the pipe end Oa in the state
where the nuin body 3a closely contacts the outer circumferential surface and the end
surface of the pipe end Oa of the steel pipe 0, and thus, the pipe end seal mechanism 3
seals the inside of the pipe end Oa of the steel pipe 0 along with the pipe inside seal
mechanism 2.
[0025]
A liquid discharge port 3c and a liquid discharge promotion tnechanisnl3b 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 mechanis~n3 is mounted to the steel
pipe 0.
[0026]
The liquid discharge promotion mechanism 3b promotes discharging of used
plating solution. The liquid discharge pro~notionm echanism 3b is not limited to a
specific type if it can promote the discharging of the plating solution, and as shown in
FIG. 1, is preferably an atmosphere opening port 3b which is disposed at a position
above the steel pipe 0 in the pipe end seal nlechanis~n 3.
[0027]
A configuration may be adopted in which an electron~agneticv alve (not
shown) is disposed at the atn~osphereo pening port 3b and the atmosphere opening port
3b is opened and closed. Alternatively, a hose is mounted to the atmosphere 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. Alternatively, the discharging of the used plating solution
may be promoted by feeding co~npresseda ir from the atmosphere opening port 3b to
the inner portion of the pipe end Oa, or the like.
[0028]
If the used plating solution is not rapidly discharged after the electro plating
layer is formed, the electro plating layer may col~odean d color of the layer may be
changed. Howevel; as described above, since the atmosphere 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 electro plating layer formed on the
female screw Ob can be suppressed.
[0029]
[Insoluble Electrode 41
The insoluble electrode 4 is a hollow cylindrical electrode (anode) for forming
the electro plating layer on the female screw Ob aud is disposed in the pipe end Oa of
the steel pipe 0 so as to be opposite to the female screw Ob. It is preferable that the
central axis of the insoluble electrode 4 be disposed so as to coincide with the pipe axis
AX of the steel pipe 0. That is, when viewed in the pipe axial direction of the steel
pipe 0, it is preferable that the steel pipe 0 and the insoluble electrode 4 have a
concentric relationship. The insoluble electrode 4 is disposed in this way, and thus,
an electro plating layer having high uniformity call be formed on the surface of the
female screw Ob which is carved on the inner circumferential surface of the pipe end
Oa.
[0030]
As the insoluble electrode 4, it is preferable that an electrode, in which an
iridium oxide coating titanium plate or stainless steel plate, or the like is formed in a
cylindrical shape, be used.
[003 11
An energizing bar 6 for energizing the insoluble electrode 4 penetrates the
main body 3a of the pipe end seal 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.
[0032]
If a potential difference is applied between the insoluble electrode 4 and the
steel pipe 0 while the plating solution is supplied between the female screw Ob and the
insoluble electrode 4 by the plating solution feed mechanism 5 described below, the
electro plating layer is formed on the surface of the female screw Ob.
[0033]
Since the insoluble electrode 4 is well known by a person skilled in the art,
further descriptions with respect to the insoluble electrode 4 are omitted.
[0034]
[Plating Solution Feed Mechanism 51
The plating solution feed mechanism 5 supplies the plating 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 supporting mechanism (not shown) which is provided on the pipe end
seal mechanism 3.
Hereinafter, a configuration of the plating solution feed mechanism 5 will be
described in detail with reference 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 viewed outside of
the steel pipe 0 from inside of the steel pipe 0 in the pipe axial direction of the steel
pipe 0).
[0035]
As shown in FIGS. 1 and 2, the plating solution feed mechanism 5 includes a
plurality of (three as an example in the present embodiment) plating solution injection
nozzles 5a, 5b, and 5c which extend radially with the pipe axis AX of the steel pipe 0
as the center. As show in FIG. 2, when viewed in the pipe axial direction of the steel
pipe 0, tips (refer to reference numerals 5a-1,5b-1, and 5c-1 in FIG. 2) of the
respective plating solution injection nozzles 5a, 5b, and 5c are disposed between the
female screw Ob and the insoluble electrode 4.
[0036]
In addition, when viewed in the pipe axial direction of the steel pipe 0, the
respective plating solution injection nozzles 5a, 5b, and 5c inject the plating solution
from injection ports (refer to reference nulnerals 5d, 5e, and 5f in FIG. 2) formed on
each tip of the nozzles toward directions which intersect extension directions (refer to
reference riunlerals R1, R2, and R3 in FIG. 2) of the plating solution injection nozzles,
the directions being rotational directions of a clockwise direction or a
counterclockwise direction in which the pipe axis AX is the centrel: Hereinaftel; the
directions in which the plating solution is injected from the respective plating solution
injection nozzles 5a, 5b, and 5c are referred to as plating solution injection directions
(xefer to reference numerals S1, S2, and S3 in FIG. 2).
Moreover, as described above, the respective plating 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 unplated regions
effectively, it is preferable that the respective plating 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 of the female screw Ob.
[0037]
As shown in FIG. 2, the extension direction R1 of the plating solution
injection nozzle 5a intersects the plating 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 of the plating solution injection nozzle 5a and the plating
solution injection direction S1 is not limited to 90°, and may be appropriately set
according to the dimensions of the steel pipe 0 and the insoluble electrode 4 or the like
so that a uniforn~e lectro plating layer is formed on the surface of the female screw Ob.
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
Ob is the clockwise direction, it is preferable that all 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 is the center.
Moreover, an angle between adjacent plating solution injection nozzles may
be appropriately set according to the total nuinber of the plating solution injection
nozzles. For example, in the present embodiment, 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'.
[0038]
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, Sb, and 5c are inclined toward the pipe end Oa side. In order words, the
extension directions R1, R2, and R3 of the respective plating solution injection nozzles
5a, Sb, and 5c are inclined with respect to the pipe axis AX of the steel pipe 0.
For example, it is preferable that an inclined angle (reference numeral 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 the like so that a uniform electro plating layer is
formed on the surface of the female screw Ob. 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 Inore 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 unifor~nityw as fornled.
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 similar to the above.
[0039]
According to the electro plating device 1 of the present embodiment described
above, the uniform electro plating layer can be formed without an uuplated region on
the surface of the female screw Ob carved on the imier circumferential surface of the
pipe end Oa of the steel pipe 0. Hereinafter, the reasons will be described.
[O040]
When the electro plating layer is forined on the screw surface of the steel pipe
0, a method which separates 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.
[O04 11
However, the plating surface is a surface of a screw arld inicludes thread ridges
and thread bottoms. Thereby, the jet is weak at thread bottoms while the jet is strong
near the surfaces of tl~eadri dges. Siuce 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 separated from the thread bottoms until the minute bubbles are
collected in the thread bottot~ls( grooves of the screw) and beconle large bubbles. The
unplated region which really occurs is a sll~aldl ot-like region. Moreover, the screw
\vl~ichi s used for fastening ~ilelilbersis forlned in a tluee-dimensio~ials piral shape.
[0042]
As the method whcli separates 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 Ob and the insoluble electrode 4 by a plurality of, that is,
two or iixore plating solution injection nozzles. However, when a single plating
solution injection nozzle is used, sufficie~j~ett effects cantlot be obtained.
[0043]
Moreover, even when thee plating solution injection nozzles are installed on
the tips of tlie supply port, if tlie plating solution injection direction of each plating
solution injection nozzle is not appropriate, a pressure balance between the plating
solution injection nozzles cannot be appropriately adjusted, and sufficient jet effects
cannot be obtained.
[0044]
Therefore, the plurality of plating solution injection nozzles are disposed at
the supply port of the center of tlie pipe end Oa 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.
[0045]
Specifically, as shown in FIGS. 1 and 2, the tips of the respective plating
solution injection ~iozzles5 a, 5b, and 5c are inclined to the pipe axis AX of the steel
pipe 0 to be plated. It is preferable that thee or more plating solution injection
nozzles be provided. Moreover, it is preferable that the plating sol~rtionin jection
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 tlie surface of the female screw Ob to be plated.
[0046]
It is preferable 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, tliat is, a tip Oa-1 of the pipe end Oa of the steel pipe 0 so tliat bubbles are
separated fro111 tlie entire region of the surface of the female screw Ob.
[0047]

Moreover, it is preferable that the tip surfaces of respective plating solution
injection nozzles Sa, Sb, and 5c be positioned between the female screw Ob and the
insoluble electrode 4 in a radial direction of tlie steel pipe 0.
[0048]
The tips of the respective plating solution injection nozzles Sa, Sb, and 5c are
linearly formed toward the female screw Ob. However, for example, a portion of the
tip including the tip surface of each of the plating solution it~jectionn ozzles 5a, Sb, and
5c may be inclined toward the outside in tile 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 uniformity of the spiral jet which is formed between the
female screw Ob and the insoluble electrode 4. In addition, even in tlie case where a
poition of the tip including the tip surface of each of the plating solutioli it~jection
nozzles Sa, Sb, 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-plated is changed, it is preferable
that orientation directions @latitlg solution injection directions) of the respective
plating solution injection nozzles Sa, Sb, and 5c be appropriately corrected according
to the diameter of the steel pipe 0, tlie dimensions of the female screw Ob, or the like.
[0049]
As described above, in the electro plating device 1 of the present embodiment,
since a uniform spiral jet can be formed between the female screw Ob and the insoluble
electrode 4, the bubbles remailiing on the thead bottoms of the female screw Ob can be
effectively removed.
Therefore, according to the electro plating device 1 of the present
emnbodimel~tt,h e uniform electro plating layer call be formed witliout an unplated
region on the surface of the female screw Ob carved 011 the imier circumferelltial
surface of the pipe end Oa of the steel pipe 0.
In addition, according to the electro plating device 1 of the present
embodiment, since the atmosphere opening port 3b is provided in the pipe end seal
n~echanism3 and thus, the used plating 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.
[OOSO]
Moreover, the present invention is not limited to the above-described
embodiment, and there may be modification example below. For example, instead of
the plating solution feed mechanism 5 shown in FIGS. 1 and 2, a plating solution feed
~neclianism7 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 line B-B of FIG. 3 (that is, a view when is viewed
outside of the steel pipe 0 fio~nin side of the steel pipe 0 in a pipe axial direction of a
steel pipe 0).
[OOS 11
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 present
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 axial direction of the steel pipe 0, tips (refer to reference 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 Ob and the insoluble electrode 4.
[0052]
In addition, w11en viewed in the pipe axial direction of the steel pipe 0, the
respective plating solution injection nozzles 7a, 7b, and 7c inject the plating solution
from injection ports (refer to reference nurnerals 7d, 7e, and 7f in FIG.4) fornled on
each tip of the nozzles toward directions which intersect extension directions (refer to
reference 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 wluch the pipe axis AX is the center. Hereinaftel; the
directions in which the plating solution is injected fiom the respective plating solution
injection nozzles 7a, 7b, and 7c are refelred to as plating solution injection directions
(refer to reference numerals S 11, S12, and S 13 in FIG.4).
Moreover, as described above, the respective plating solution injection
directions SI 1, S12, and S13 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 unplated regions
effectively, it is preferable that the respective plating solution injection directions Sll,
S12, and S13 are set to the same rotational direction of the clockwise direction or the
counterclockwise direction as the screw cutting direction of the female screw Oh.
[0053]
As shown in FIG 4, the extension direction RS 1 of the plating solution
injection nozzle 7a intersects the plating solution injection direction S11. However,
both (RIS and S11) 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 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 electrode 4 or the like
so that a uniforlli electro plating layer is formed on tlie surface of the female screw Ob.
A relationship between tlie cxtensio~di irection R12 of the plating solution
iujection nozzle 7b and the plating solutioti iujection direction S12 and a relationship
between the exte~isiod~ilr ectio~Ri 13 of the plating solution injectio~ni ozzle 7c and the
plating solution injection direction S13 are similar to the above.
In addition, for example, when the screw cutting direction of tlie female screw
Ob is the right-handed rotation, it is preferable that all of the plating solution injection
directions S11, S12, and S 13 are set so as to face the rotational direction of tlie
clockwise direction in which the pipe axis AX is the center.
Moreover, an angle between adjacent plating solution injection ~lozzlems ay
be appropriately set accordit~gto the total number of the plating solution injection
nozzles. As shown in FIG. 4, wlieti 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°.
[0054]
In addition, as shown in FIG. 3, when viewed in the direction perpendicular to
tlie pipe axial direction of the steel pipe 0, the respective plating solutioli injection
nozzles 7a, 7b, and 7c are perpendicular to the pipe axial direction of the steel pipe 0.
In other words, the extension directions R11, R12, and R13 of the respective plating
solution injection nozzles 7a, 7b, and 7c are perpe~idicularto the pipe axial direction of
tlie steel pipe 0.
In addition, for example, as shown in FIG. 5, when viewed in tlie extension
direction R11 of the plating solution injection ~lozzle72 1, the plating solution injection
nozzle 7a injects the plating solution toward the direction which is inclined from a
reference direction V perpendicular to the pipe axial direction and the extension
direction R11 to the pipe end Oa side.
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 Oa side.
[0055]
It is preferable that an inclined angle (reference numeral a2 in FIGS) between
the plating solution injection direction S11 of the plating solution injection nozzle 7a
and the reference 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 fornied on the surface of the fenlale screw Ob. According to examination
conducted by the inventors, it was established that uniform electro plating layer was
fornied without an unplated region if the inclined angle a2 was set to a range more
than 0' and less than or equal to 45' (niore preferably, a range more than 0' and less
than or equal to 20').
In addition, the plating solution injection nozzle 7a may inject the plating
solution in tlie reference direction V. In this case, the plating solution injection
direction S11 of the plating solution injection nozzle 7a and the reference direction V
coincide with each other (that is, the inclined angle a2= 0"). Also in this case, it was
established that the electro plating layer having high uniformity was fonned. The
plating solution injection nozzles 7b and 7c are also similar to the above.
[Example]
[0056]
Hereinaftel; Examples of the present invention will be described.
A degreasing liquid (sodium hydroxide = 50 g/L), a Ni-strike bath (nickel
chloride = 250 g/L and 1~~~drocliloacridc = 80 g/L), and a copper plating bath (copper
sulfate = 250 g/L and sulfuric acid = 110 g/L) were prepared, and copper plating was
performed by processes and conditions shown in Table 1 using the electro plating
device 1 shown in FIG 1.
[0057]
[0058]
By changing the plating solution injection nozzle type, the number of the
plating solution injection nozzles, and the presence or absence of the atmosphere
opening port, the presence or absence of an unplated region (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 sho~vnin 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 seal mechanism individually and supplied the plating solution from the outside of
the pipe via hoses individually. Additionally, in a column of a "nozzle type" of Table 2,
a colntnon 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.
[0059]
[Table 21
[Table 11
Process
Trzatment
Condition
Clxssification
Cathode Eleetrol>lic Uegrcasitlg
NolrleTlye
Bath
Te~uperature
rC)
50
Ni-Strike
Number of Nozzle
Currcnt
Density
(A/dniZ)
6
Bath
Temperature
rC)
35
Copper plating
Treatment
Time
(second)
60
Bat11
Temperature
PC)
50
Upper Portion
Atmosphere
Opening Port
Current
Density
I
6
Trealrne81t
Time
(second)
120
Currellt
Density
(Ndm')
8
Unplating
Treablest
Time
(second)
400
Change of Color
of Surface
As shown in FIG. 2, when the plating solution injection nozzle was
individually provided outside the pipe (Comparative Examples 1 and 2), even though
the number of the plating solutio~iln jection nozzles was 3, a uniform spiral jet could
not be obtained, and unplated regions occurred.
[0061]
On the other hand, m~lienth ree or more plating solution injection nozzles were
provided in common inside the pipe (Examples 1 and 2), it was understood that the
unplated region did not occur. This was considered because bubbles remaining on the
thread bottoi~lso f the female screw were effectively removed by forming a uniform
spiral jet between the female screw and the anode of the insoluble electrode.
[0062]
111 addition, it was confirmed that the plating solution was rapidly discharged
by providing the atmosphere opening poit at the position of the upper portion of the
pipe and the change of the color of the surface of the electro plating layer did not
occur.
[0063]
Moreover, it was found that although the unplated regions slightly occurred in
Exanlple 3 (when the number of plating solutiotl injection nozzles were two) of Table
2, it was level witlioout problems, and removal effects of the bubbles were sufficient.
[0064]
As understood from the results, in order to prevent the unplated regions from
occur~ingd ue to the staying of the oxygen gas generated from the anode at the time of
plating, the method applying the jet is considered. It is effective in a case of a flat
shape only by providing the plating solution injection nozzle outside the pipe.
Ho\vever, in the spiral screw shape, bubbles stay on the thread bottoms and unplated
regions occur, Even when the number of the plating solution injection nozzles is
increased, a uniform jet is not obtained, and the unplated regions occur.
[0065]
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 fetnale screw and the insoluble electrode, remaining bubbles on
the thread bottoms are effectively removed, and occurrence of the unplated regions can
be prevented. The number of the plating solution injection nozzles is preferably 3,
and thus, occurrence of the unplated regions can be securely prevented. In addition,
the plating solution is rapidly discharged by providing the atmospl~ereo pening port,
and the change of the color of the surface of the plated female screw does not occur.
[Description of Reference Nunlerals and Signs]
[0066]
0: steel pipe
Oa: pipe end
Oa-1: tip of pipe end
Ob: female screw
Oc: predetermined position
1: electro plating device
2: pipe inside seal ~nechanism
3: pipe end seal mechanism
3a: main body
3b: liquid discharge promotion mechanism (atmosphere opening port)
3c: liquid discharge port
4: insoluble electrode
5 and 7: plating solution feed mechanism
5a, Sb, and 5c: plating solution injection nozzle
7a, 7b, and 7c: plating solution injection nozzle
5a-1, 5b-1, and 5c-I: tip of plating solution ejection nozzle
7a-1, 7b-1, 7c-1: tip of plating solution injection nozzle
6: energizing bar

CLAIMS
[Claim 1]
An electro plating device which forms an electro plating layer on a surface of
a female screw carved on an inner circumferential 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 fro111 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 radially with a pipe axis of the steel pipe as a center, and is disposed outside the
pipe end; and
a pipe end seal mechanism which accommodates the nozzles thereinside and
is mounted to the pipe end in a state where the pipe end seal mechanism closely
contacts an outer circumferential surface of the pipe end,
wherein 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 from an injection port formed
on the tip toward a direction which intersects an extension directio11 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.
[Claim 2]
The electro plating device according to claim 1,
where in each of the nozzles is perpendiculator the pipe axial direction or is
inclined toward the pipe end side.
[Claim 3]
The electro plating device according to claim 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 injects the plating solution in a direction which is inclined
from the reference directiou to the pipe end side.
[Claim 4]
The electro plating device according to any one of claims 1 to 3,
wherein the plating solution feed mechanism includes three nozzles.
[Claim 5]
The electro plating device according to any one of claims 1 to 4,
wherein the pipe end seal mechanism further includes:
a discharging port for discharging a used plating solution; and
a liquid discharge prolnotion mechanism for p~on~otindgis charging of the
used plating solution.
[Claim 6]
The electro plating device according to claim 5,
wherein the liquid discharge promotion mechanism is an atmosphere opening
portion which is disposed at a position above the steel pipe in the pipe end seal
mechanism.