U.S. patent application number 10/434513 was filed with the patent office on 2003-11-20 for torch for powder plasma buildup welding.
This patent application is currently assigned to Nippon Welding Rod Co., Ltd.. Invention is credited to Imai, Minoru, Onitsuka, Yoshimi.
Application Number | 20030213781 10/434513 |
Document ID | / |
Family ID | 18946811 |
Filed Date | 2003-11-20 |
United States Patent
Application |
20030213781 |
Kind Code |
A1 |
Onitsuka, Yoshimi ; et
al. |
November 20, 2003 |
Torch for powder plasma buildup welding
Abstract
A torch for powder plasma buildup welding capable of readily
attaining welding in conformity to any size of a pipe material to
be subjected to welding, any configuration thereof and the like. A
torch head is replaceably connected to a torch body. The torch body
is provided with a gap formation spacer member which is abutted
against an inner peripheral surface of the pipe material to keep a
distance between an opening of a convergent nozzle of the torch
head and the inner peripheral surface of the pipe material
substantially constant during buildup welding. Also, the torch body
is provided with a deflection restraint spacer member which is
abutted against the inner peripheral surface of the pipe material
to prevent deflection of the torch body in the pipe material during
buildup welding.
Inventors: |
Onitsuka, Yoshimi; (Tokyo,
JP) ; Imai, Minoru; (Tokyo, JP) |
Correspondence
Address: |
PEARNE & GORDON LLP
526 SUPERIOR AVENUE EAST
SUITE 1200
CLEVELAND
OH
44114-1484
US
|
Assignee: |
Nippon Welding Rod Co.,
Ltd.
Tokyo
JP
|
Family ID: |
18946811 |
Appl. No.: |
10/434513 |
Filed: |
August 1, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10434513 |
Aug 1, 2003 |
|
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09956229 |
Jan 24, 2002 |
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6621038 |
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Current U.S.
Class: |
219/121.45 ;
219/121.36 |
Current CPC
Class: |
H05H 1/3423 20210501;
H05H 1/34 20130101; B23K 15/00 20130101 |
Class at
Publication: |
219/121.45 ;
219/121.36 |
International
Class: |
B23K 009/02 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 28, 2001 |
JP |
92333-2001 |
Claims
What is claimed is:
1. A torch for powder plasma buildup welding, comprising: a torch
head adapted to be inserted into a pipe material of a continuous
length to carry out buildup welding on an inner peripheral surface
of the pipe material; and a torch body formed into a continuous
length and having said torch head mounted on a distal end thereof;
said torch head being replaceably connected to said torch body.
2. The torch as defined in claim 1, wherein said torch head
includes a convergent nozzle having an opening; and either said
torch head or said torch body is provided with a gap formation
spacer member which is abutted against the inner peripheral surface
of the pipe material to keep a distance between said opening of
said convergent nozzle of said torch head and the inner peripheral
surface of the pipe material substantially constant during welding.
Description
BACKGROUND OF THE INVENTION
[0001] This invention relates to a torch for powder plasma buildup
welding, and more particularly to a powder plasma buildup welding
torch wherein a torch head is inserted into a pipe material to be
subjected to buildup welding, to thereby carry out the welding on
an inner peripheral surface of the pipe material.
[0002] A typical torch for powder plasma buildup welding which has
been conventionally known or practiced in the art includes a torch
head and a torch body for connecting a body of a welding machine
such as a power supply or the like and the torch head to each other
therethrough and is adapted to carry out buildup welding on an
inner peripheral surface of a pipe material. Such a welding
equipment is constructed so as to rotate the pipe material while
keeping the torch head and a part of the torch body inserted into
the pipe material and move the torch head in the pipe material to
form a spiral padding on the inner peripheral surface of the pipe
material, to thereby attain buildup welding on the pipe material.
Such a torch for powder plasma buildup welding is used to carry out
buildup welding on an inner surface of a pipe material for a
petroleum reaction pipe, an injection molding cylinder or the like
using a welding material which has corrosion resistance and wear
resistance.
[0003] Unfortunately, the conventional powder plasma buildup
welding torch must be varied in construction depending on
dimensions of a pipe material, a configuration thereof and the
like, resulting in handling thereof being troublesome. In a powder
plasma buildup welding torch, the torch body is formed of a rigid
material, to thereby fail to construct the whole torch in a compact
manner, so that transport of the torch is troublesome. This renders
repairing of the torch head highly hard when any failure or trouble
occurs in the torch head.
SUMMARY OF THE INVENTION
[0004] The present invention has been made in view of the foregoing
disadvantage of the prior art.
[0005] Accordingly, it is an object of the present invention to
provide a torch for powder plasma buildup welding which is capable
of being readily handled irrespective of dimensions of a pipe
material, a configuration thereof and the like.
[0006] It is another object of the present invention to provide a
torch for powder plasma buildup welding which is capable of
facilitating repairing of a torch head when it fails or breaks
down.
[0007] It is a further object of the present invention to provide a
torch for powder plasma buildup welding which is capable of
restraining a variation in distance between an opening of a
convergent nozzle of a torch head and an inner peripheral surface
of a pipe material to be subjected to welding, to thereby form a
padding uniform in size thereon.
[0008] It is still another object of the present invention to
provide a torch for powder plasma buildup welding which is capable
of preventing leaping of a torch body.
[0009] In accordance with the present invention, a torch for powder
plasma buildup welding is provided. The torch includes a torch head
adapted to be inserted into a pipe material of a continuous length
to carry out buildup welding on an inner peripheral surface of the
pipe materiall and a torch body formed into a continuous length and
having the torch head mounted on a distal end thereof. The torch
head is replaceably connected to the torch body. Such construction
permits buildup welding to be attained in conformity to any size of
a pipe material to be subjected to welding, any configuration
thereof and the like. Thus, the present invention facilitates
application of the torch to welding while eliminating replacement
of the whole powder plasma buildup welding torch required in the
prior art. Also, when any failure or trouble occurs in the torch
head, the torch head may be readily repaired because it is detached
from the torch body.
[0010] In general, the torch head includes a convergent nozzle
having an opening. In a preferred embodiment of the present
invention, either torch head or torch body is provided with a gap
formation spacer member which is abutted against the inner,
peripheral surface of the pipe material to keep a distance between
the opening of the convergent nozzle of the torch head and the
inner peripheral surface of the pipe material substantially
constant when welding takes place. Such arrangement of the gap
formation spacer member in the torch effectively prevents a
variation in distance between the opening of the convergent nozzle
of the torch head and the inner peripheral surface of the pipe
material subjected to welding due to a weight of the torch head
and/or deflection of the torch body, to thereby ensure formation of
a padding of a uniform size on the inner peripheral surface of the
pipe material.
[0011] An increase in length of the torch body tends to cause it to
be deflected in the pipe material during build up welding. In
particular, arrangement of the gap formation spacer member causes
leaping of the torch body during rotation of the pipe material
depending on abutment between the gap formation spacer member and
the inner peripheral surface of the pipe material, leading to an
increase in deflection of the torch body. In view of such a
disadvantage, the torch body is preferably provided with at least
one deflection restraint spacer member adapted to be abutted
against the inner peripheral surface of the pipe material so as to
prevent deflection of the torch body in the pipe material during
buildup welding.
[0012] More specifically, in accordance with the present invention,
a following torch for powder plasma buildup welding is provided.
The torch includes a torch head adapted to be inserted into a pipe
material of a continuous length to carry out buildup welding on an
inner peripheral surface of the pipe material and a torch body
formed into a continuous length and having the torch head mounted
on a distal end thereof. The torch body includes a connection pipe
and a plurality of pipes arranged in said connection pipe. The
plurality of pipes feed cooling water, gas and the like to said
torch head, respectively. The plurality of pipes include two or
more pipes made of an electrically conductive material. One of the
two or more pipes constitutes a first conductive portion
electrically connected to one of electric poles of a DC power
supply and another of the two or more pipes constitutes a second
conductive portion electrically connected to the other of said
electric poles. The torch head includes a bar-like electrode, an
electrode support made of an electrically conductive material and
arranged for supporting the bar-like electrode, a convergent nozzle
made of an electrically conductive material, a nozzle support made
of an electrically conductive material and arranged for supporting
said convergent nozzle, and a head-side insulation member arranged
between the electrode support and the nozzle support to
electrically insulate the electrode support and nozzle support from
each other. The head-side insulation member includes a projection
portion projecting beyond the electrode support and nozzle support
and toward the torch body. The connection pipe of the torch body is
fixedly provided on an end thereof defined on a side of the torch
head with an insulation flange. The insulation flange is attached
with a connection member. The connection member includes a first
connection member half and a second connection member half which
are arranged so as to be spaced from each other through a cavity
defined therebetween and fitted with the projection portion. One of
the two or more pipes mentioned above is connected with the first
connection member half through the insulating flange. Another of
the two or more pipes mentioned above is connected with the second
connection member half through the insulating flange. The electrode
support is contacted with the first connection member half. The
nozzle support is contacted with the second connection member half.
The torch head is replaceably connected to the torch body by means
of a plurality of bolts for fixing the torch head and connection
member to each other.
[0013] The torch of the present invention thus constructed
facilitates detachable connection between the connection member and
the torch head by tightening and releasing of the bolts. This
permits the torch head to be replaceably connected to the torch
body by means of bolts. Also, connection between the connection
member and the torch head leads to joining between the first
connection member half and the electrode support, so that a current
may be fed from one of electric poles of a power supply (a body of
a welding machine) through one of the two or more pipes
constituting a first conductive portion, the first connection
member half and the electrode support to the bar-like electrode.
Also, connection between the connection member and the torch head
permits the second connection member half and nozzle support to be
joined together, so that a current may be fed from the other
electric pole of the power supply (the body of the welding machine)
through another of the two or more pipes constituting a second
conductive portion, the second connection member half and the
nozzle support to the convergent nozzle.
[0014] In this invention, particularly, the head-side insulation
member includes the projection portion. Thus the positioning
between the torch head and the torch body is easily performed only
by fitting the projection portion into the cavity defined between
the first connection member half and the second connection member
half. The connection member may be attached with the insulation
flange by means of the bolts for fixing the torch head and the
connection member to each other. This permits the torch head, the
connection member and the insulation flange to be fixed together by
means of a small number of bolts.
[0015] In a preferred embodiment of the present invention, the
first connection member half and the second connection member half
each are formed with a plurality of connection member-side bolt
insertion through-holes. The flange is formed with a plurality of
flange-side bolt insertion through-holes aligned with the
connection member-side bolt insertion through-holes, respectively.
The flange-side bolt insertion through-holes each include a large
diameter portion receiving therein each head of the bolts and a
small diameter portion receiving therein each shank of the bolts.
The electrode support and the nozzle support each are formed with a
plurality of threaded holes aligned with the connection member-side
bolt insertion through-holes, respectively. The torch head is
detachably connected to the torch body by means of bolts threadedly
fitted in the threaded holes of the torch head through the
connection member-side bolt insertion through-holes and flange-side
bolt insertion through-holes. Such construction permits the
connection member and torch head to be connected to each other by
inserting bolts through the connection member-side bolt insertion
through-holes and flange-side bolt insertion through-holes and
threadedly fitting the bolts in the threaded holes of the torch
head. Release of the bolts leads to separation of the connection
member and torch head from each other.
[0016] In a preferred embodiment of the present invention, the
insulation flange is formed with flange-side through-holes via
which the pipes of the torch body extend and the connection member
is formed with fit holes which communicate with the flange-side
through-holes and in which the pipes are fitted and communication
holes which communicate with the fit holes and are open on-a side
of the torch head. The torch head is formed with in-head passages
aligned with the communication holes. The torch head is connected
to the torch body so that the communication holes and in-head
passages may communicate with each other at communication portions
therebetween. Thus, connection between the connection member and
the torch head leads to communication between the communication
holes and the in-head passages, so that a current, cooling water,
gas and the like may be fed from the body of the welding machine to
the torch head.
[0017] In a preferred embodiment of the present invention, the
communication portions, at which the communication holes and
in-head passages communicate with each other, each are sealed at a
peripheral edge thereof with an O-ring which is arranged at an
opening of each of the communication holes on a side of the torch
head or an opening of each of the in-head passages on a side of the
connection member. This permits the peripheral edge of the
communication portion between the communication holes and the
in-head passages to be effectively sealed with the O-ring
compressed due to tightening of the bolts.
[0018] In a preferred embodiment of the present invention, the
torch body is provided on an end thereof defined on a side of the
torch head with an above-mentioned gap formation spacer member and
the torch body is provided with an above-mentioned deflection
restraint spacer member.
[0019] The gap formation spacer member may be constructed in any
desired manner. For example, the gap formation spacer member may
include an upper head support half and a lower head support half
which are combined with each other to circumferentially surround
the torch body. In this instance, the lower head support half may
include a lower body portion for circumferentially surrounding a
lower portion of the torch body and a lower projection portion
arranged so as to vertically downwardly project from the lower body
portion, resulting in being abutted against the inner peripheral
surface of the pipe material. The upper head support half may
include an upper body portion for circumferentially surrounding an
upper portion of the torch body and an upper projection portion
arranged so as to project from the upper body portion in a radial
direction of the pipe body, resulting in being abutted against the
inner peripheral surface of the pipe material. The upper projection
portion may have, to the lower projection portion, positional
relationship which is set to restrain a variation in distance
between the torch head and the inner peripheral surface of the pipe
material during welding.
[0020] In a preferred embodiment of the present invention, the
lower projection portion includes a projection body threadedly
coupled to the lower head support half and a ball member supported
in the projection body in a rollable manner (hereinafter also
referred to as "rollably") so as to be abutted against the inner
peripheral surface of the pipe material. This permits rotation or
rolling of the ball member to reduce friction between the lower
projection portion and the inner peripheral surface of the pipe
material, to thereby reduce deflection of the torch body in the
pipe material during buildup welding.
[0021] In a preferred embodiment of the present invention, the
insulation flange is formed into a cylindrical configuration and
constitutes the gap formation spacer member. In this instance, the
insulation flange may be abutted against the inner peripheral
surface of the pipe material. This eliminates a necessity of
providing the gap formation spacer member separately and simplifies
a structure of the gap formation spacer member.
[0022] The deflection restraint spacer member may be likewise
constructed in any desired manner. For example, the deflection
restraint spacer member may include an upper body support half and
a lower body support half which are combined with each other to
circumferentially surround the torch body, as well as an abutment
member arranged so as to vertically downwardly project from the
lower body half, resulting in being abutted against the inner
peripheral surface of the pipe material. The abutment member may be
formed into a plate-like shape and arranged so as to extend in a
longitudinal direction of the pipe material to be welded. Also, the
deflection restraint spacer member may be constituted by a
cylindrical member. The cylindrical member may include a first body
support half and a second body support half which are combined with
each other to circumferentially surround the torch body.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] These and other objects and many of the attendant advantages
of the present invention will be readily appreciated as the same
becomes better understood by reference to the following detailed
description when considered in connection with the accompanying
drawings; wherein:
[0024] FIG. 1 is a schematic view showing a manner of buildup
welding on an inner peripheral surface of a pipe material in
accordance to an embodiment of a torch for powder plasma buildup
welding according to the present invention;
[0025] FIG. 2 is a sectional view showing a structure around a
torch head incorporated in the torch for powder plasma buildup
welding shown in FIG. 1;
[0026] FIG. 3 is a front elevation view showing a torch head
incorporated in the torch for powder plasma buildup welding of FIG.
1;
[0027] FIG. 4 is a plan view showing a torch head incorporated in
the torch for powder plasma buildup welding of FIG. 1;
[0028] FIG. 5 is a rear view showing a torch head incorporated in
the torch for powder plasma buildup welding of FIG. 1;
[0029] FIG. 6 is a plan view showing a first connection member
incorporated in the torch for powder plasma buildup welding of FIG.
1, which is viewed from a side of a torch body;
[0030] FIG. 7 is a plan view showing a second connection member
incorporated in the torch for powder plasma buildup welding of FIG.
1, which is viewed from a side of a torch body;
[0031] FIG. 8 is a plan view showing an insulation flange
incorporated in the torch for powder plasma buildup welding of FIG.
1, which is viewed from a side of a torch body;
[0032] FIG. 9 is a plan view showing a gap formation spacer member
incorporated in the torch for powder plasma buildup welding of FIG.
1;
[0033] FIG. 10 is a side elevation view showing a gap formation
spacer member incorporated in the torch for powder plasma buildup
welding of FIG. 1;
[0034] FIG. 11 is a sectional view taken along line XI-XI of FIG.
10;
[0035] FIG. 12 is a side elevation view showing a deflection
restraint spacer member incorporated in the torch for powder plasma
buildup welding of FIG. 1;
[0036] FIG. 13 is a bottom view showing a deflection restraint
spacer member incorporated in the torch for powder plasma buildup
welding of FIG. 1;
[0037] FIG. 14 is a sectional view taken along line XIV-XIV of FIG.
12:
[0038] FIG. 15 is a plan view showing a structure around a torch
head incorporated in another embodiment of a torch for powder
plasma buildup welding according to the present invention;
[0039] FIG. 16 is a partially broken-away side elevation view of
the structure shown in FIG. 15;
[0040] FIG. 17 is a bottom view of the structure shown in FIG.
15;
[0041] FIG. 18 is a plan view showing an insulation flange
incorporated in the torch for powder plasma buildup welding of FIG.
15, which is viewed from a side of a torch body;
[0042] FIG. 19 is a plan view showing a deflection restraint spacer
member incorporated in a further embodiment of a torch for powder
plasma buildup welding according to the present invention;
[0043] FIG. 20 is a side elevation view showing a modification of
the deflection restraint spacer member incorporated in a still
another embodiment of a torch for powder plasma buildup welding
according to the present invention; and
[0044] FIG. 21 is a sectional view taken along line XXI-XXI of FIG.
20.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0045] Now, a torch for powder plasma buildup welding according to
the present invention will be described with reference to the
accompanying drawings.
[0046] Referring first to FIG. 1, a manner of buildup welding on an
inner peripheral surface of a pipe material carried out in
accordance with an embodiment of a torch for powder plasma buildup
welding according to the present invention is illustrated. A torch
for powder buildup welding of the illustrated embodiment which is
generally designated at reference numeral 1 in FIG. 1 includes a
torch head 3, a torch body 5 of a continuous length, a gap
formation spacer member 7, and a deflection restraint spacer member
9. The torch head 3 and a part of the torch body 5 are inserted
into a pipe material P of a continuous length to be subjected to
buildup welding. Then, the pipe material P is rotated and the torch
head 3 is moved in the pipe material P, so that buildup welding is
carried out on an inner peripheral surface of the pipe material P
to form a spiral padding W thereon. In the illustrated embodiment,
the pipe material P is formed into an inner diameter of 120 mm. The
torch body 5, as shown in FIG. 2, includes a connection pipe 11 and
pipes 13, 15 and 17 arranged in the connection pipe 11 so as to
flow a DC current, gas and the like therethrough. This results in a
DC current, gas and the like being fed from a body of a welding
machine (not shown) to the torch head 3. In the illustrated
embodiment, the torch body 5 is formed into a length of about 5 m.
Eight such pipes are arranged so as to feed a DC current, gas and
the like therethrough to the torch head 3. However, only three
pipes 13, 15 and 17 are shown in FIG. 2 for the sake of brevity.
The connection pipe 11 includes a pipe body 11a and a
small-diameter end portion or an end portion reduced in diameter as
compared with the pipe body which is designated at reference
character 11b. The end portion 11b is arranged on an end of the
pipe body 11a defined on a side of the torch head 3. The pipe body
11a includes an outer wall section 11c and an inner wall section
11d, to thereby be constructed into a double-wall structure.
Between the outer wall section 11c and the inner wall section 11d
is formed a waterway lie.
[0047] The torch head 3, as shown in FIGS. 2 to 5, is connected
through a first connection member half 21 and a second connection
member half 23 constituting a connection member 19 described above,
and an insulation flange 25 to the connection pipe 11 and includes
a bar-like electrode 29, an electrode support 31 for supporting the
bar-like electrode 29 therein, a convergent nozzle 33, a nozzle
support 35 for supporting the convergent nozzle 33 therein and a
head-side insulation member 37. The bar-like electrode 29 is
supported in the electrode support 31 through a collet 39 for
adjusting centering of the bar-like electrode 29 and a collet
holder 41.
[0048] The electrode support 31 is made of an electrically
conductive material and, as shown in FIGS. 4 and 5, is formed
therein with an in-head passage 31a for feeding cooling water, an
in-head passage 31b for plasma gas and an in-head passage 31c for
discharging cooling water. The cooling water feed in-head passage
31a and cooling water discharge in-head passage 31c are arranged so
as to communicate with a first cooling water feed pipe (not shown)
of the torch body 5 and a first cooling water discharge pipe (not
shown) of the torch body through a communication hole 21d of the
first connection member half 21, respectively. This permits cooling
water fed from a side of a body of a welding machine through the
first cooling water feed pipe and cooling water feed in-head
passage 31a to the electrode support 31 to be returned through the
cooling water discharge in-head passage 31c and first cooling water
discharge pipe to the side of the body of the welding machine after
cooling a peripheral region of an upper portion of the bar-like
electrode 29. Also, the first cooling water feed pipe in the torch
body 5 connected to the cooling water feed in-head passage 31a
constitutes a first conductive portion electrically connected to a
negative electric pole of a DC power supply of the body of the
welding machine. Such construction permits a current to be fed from
the DC power supply through the first cooling water feed pipe (the
first conductive portion), first connection member half 21,
electrode support 31, collet holder 41 and collet 39 to the
bar-like electrode 29. The plasma gas in-head passage 31b is
arranged so as to communicate at one end thereof with the plasma
pipe 13 of the torch body 5 through the communication hole 21d of
the first connection member half 21 and communicate at the other
end thereof to a through-hole 37c formed through a central portion
of the head-side insulation member 37 and a through-hole 35a formed
through a central portion of the nozzle support 35. Such
construction results in plasma gas fed from the side of the body of
the welding machine through the plasma gas pipe 13 and plasma gas
in-head passage 31b being fed to a peripheral area at a distal end
of the bar-like electrode 29 via the through-holes 37c and 35a.
[0049] The convergent nozzle 33 is formed into a cylindrical shape
while being gradually reduced in diameter toward a distal end of
the bar-like electrode 29. Also, the convergent nozzle 33 is
supported in the nozzle support 35 in a manner to surround the
bar-like electrode 29 while being spaced at a predetermined
interval from the bar-like electrode 29. Further, the convergent
nozzle 33 has a shield cap 34 arranged therearound while being
threadedly fitted in the nozzle support 35.
[0050] The nozzle support 35 is made of an electrically conductive
material as in the electrode support 31 and formed therein with a
through-hole 35a in a manner to extend through a central portion
thereof, in which the bar-like electrode 29 is partially arranged.
Also, the nozzle support 35, as shown in FIGS. 4 and 5, is formed
therein with a first in-head passage 35b for a powder, an in-head
passage 35c for shield gas, a second in-head passage 35d for a
powder, an in-head passage 35e for feeding cooling water, and an
in-head passage 35f for discharging cooling water. The first powder
in-head passage 35b and second powder in-head passage 35d are
arranged so as to communicate at one end thereof through a
communication hole 23d of the second connection member half 23 to
first and second powder pipes (not shown) of the torch body 5,
respectively. Also, the first and second powder in-head passages
35b and 35d communicate at the other end thereof with a powder hole
33b. This results in a powder which is fed from the body side of
the welding machine through the powder pipes and in-head passages
35b and 35d being fed through the powder hole 33b into an arc
column discharged between bar-like electrode 29 and the pipe
material P. The shield gas in-head passage 35c is arranged so as to
communicate at one end thereof with the shield gas pipe 15 of the
torch body 5 through the communication hole 23d of the second
connection member half 23 and at the other end thereof with a
shield gas hole 33c. This permits shield gas fed from the body side
of the welding machine through the shield gas pipe 15 and shield
gas in-head passage 35c to be fed around the arc column. The
cooling water feed in-head passage 35e is arranged so as to
communicate the communication hole 23d of the second connection
member half 23 to a second cooling water feed pipe (not shown) of
the torch body 5 and the cooling water discharge in-head passage
35f is arranged so as to communicate through the communication hole
23d of the second connection member half 23 to the second cooling
water discharge pipe 17 of the torch body 5, so that cooling water
fed from the body side of the welding machine through the second
cooling water feed pipe and cooling water feed in-head passage 35e
may be returned to the body side of the welding machine through the
cooling water discharge in-head passage 35f and second cooling
water discharge pipe 17 after it cools a periphery of a lower
portion of the bar-like electrode 29. Also, the second cooling
water feed pipe of the torch 5 connected to the cooling water
in-head feed passage 35e constitutes a second conductive portion
electrically connected to a positive electric pole of the DC power
supply on the body side of the welding machine. This permits the
convergent nozzle 33 to be fed with a current from the positive
pole through the second cooling water feed pipe (the second
conductive portion), second connection member half 23 and nozzle
support 35. Thus, a so-called pilot arc is generated between a
distal end of the bar-like electrode 29 electrically connected to
the negative pole and the convergent nozzle 33 electrically
connected to the positive pole during welding.
[0051] The head-side insulation member 37 is formed of an
insulating material such as a ceramic material or the like which
has a plate-like configuration and arranged between the electrode
support 31 and the nozzle support 35 to insulate both from each
other. The head-side insulation member 37 includes an insulation
portion 37a arranged between the electrode support 31 and the
nozzle support 35 and an elongated projection portion 37b
projecting from the insulation portion 37a toward the connection
member 19 described below. The insulation portion 37a is formed
therein with the above-described through-hole 37c in a manner to
extend through a central portion thereof in a thickness direction
thereof. The through-hole 37c has a part of the bar-like electrode
29 arranged therein. The insulation portion 37a, as shown in FIGS.
2 and 4, is formed with bolt insertion through-holes 37c to 37i in
a manner to extend therethrough in a thickness direction thereof.
Of the bolt insertion through-holes 37c to 37i, the bolt insertion
through-holes 37c to 37e each have a bolt 43 arranged therein so as
to extend from the head-side insulation member 37 to the electrode
support 31. The bolt insertion through-holes 37c to 37e each are
formed into a configuration which prevents a head of the bolt 43
from being contacted with the nozzle support 35. The head-side
insulation member 37 and electrode support 31 are fixed with
respect to each other by extending the bolt 43 through each of the
bolt insertion through-holes 37c to 37e and threadedly fitting it
in each of threaded holes 31d formed in the electrode support 31.
Of the bolt insertion through-holes 37c to 37i, the bolt insertion
through-holes 37f to 37i, as shown in FIG. 2, each have a bolt 45
arranged therein so as to extend from the head-side insulation
member 37 to the nozzle support 35. The bolt insertion
through-holes 37f to 37i each are formed into a shape which
prevents a head of the bolt 45 from being contacted with the
electrode support 31. Thus, the head-side insulation member 37 and
nozzle support 35 are fixed with respect to each other by inserting
the bolt 45 through each of the bolt through-holes 37f to 37i and
threadedly fitting it in each of threaded hole 35g formed in the
nozzle support 35. Also, the electrode support 31 is formed at a
portion thereof aligned with each of the bolt insertion
through-holes 37f to 37i with a screwdriver insertion port 31e in a
manner to extend therethrough in a thickness direction thereof so
that the bolt 45 may be externally secured by means of the
screwdriver.
[0052] The connection member 19 is arranged on an end of the torch
body 5 defined on a side of the torch head 3 and is constituted by
the connection member half 21 and second connection member half 23
each formed of an electrically conductive material of a plate-like
shape. The first connection member half 21 and second connection
member half 23 are arranged so as to be spaced from each other with
a gap or cavity being defined therebetween. The cavity has the
projection portion 37b of the head-side insulation member 37 fitted
therein. More particularly, the first connection member half 21 and
second connection member half 23 are arranged in a manner to be
insulated from each other while interposing the projection portion
37b of the head-side insulation member 37 therebetween. The first
connection member half 21, as shown in FIGS. 2 and 6, is joined to
the electrode support 31 and formed with three feed holes 21a and
two connection member-side bolt insertion through-holes 21b in a
manner to extend therethrough in a thickness direction thereof. The
feed holes 21a each are formed at a lower portion of a central
section of the first connection member half 21 and include a fit
hole 21c positioned on a side of the torch body 5 and a
communication hole 21d positioned on a side of the torch head 3 and
formed into a diameter smaller than the fit hole 21c. The fit holes
21c each have each of three pipes 13 of the torch body 5 fitted
therein and the communication holes 21d each are arranged so as to
communicate with each of the pipes 13 and each of the in-head
passages 31a to 31c of the electrode support 31. The second
connection member half 23, as shown in FIGS. 2 and 7, is arranged
so as to be joined to the nozzle support 35 and formed with six
feed holes 23a and two connection member-side bolt insertion
through-holes 23b in a manner to extend there through in a
thickness direction thereof. The feed holes 23a each are formed at
a central portion of the second connection member half 23 and
include a fit hole 23c positioned on a side of the torch body 5 and
a communication hole 23d positioned on a side of the torch head 3
and formed into a diameter smaller than the fit hole 23c. The fit
holes 23c each have each of six pipes 15 and 17 of the torch body 5
fitted therein and the communication holes 23d each are arranged so
as to communicate with each of the pipes 15 and 17 and each of the
in-head passages 35b to 35f.
[0053] The insulation flange 25, as shown in FIGS. 2 and 8, is
formed of, a ceramic material into a plate-like shape and arranged
between the connection member 19 and the torch body 5 or at an end
of the torch body 5 defined on a side of the torch head 3. FIG. 8
is a plan view of the insulation flange 25 which is viewed from a
side of the torch body 5. The insulation flange 25 is formed with
eight flange-side through-holes 25a, three fixing bolt insertion
through-holes 25b and four flange-side bolt insertion through-holes
25c so as to extend therethrough in a thickness direction thereof.
The flange-side through-holes 25a are arranged rather in proximity
to a central portion of the insulation flange 25 and each have each
of the eight pipes 13, 15 and 17 arranged therein so as to extend
therethrough. The fixing bolt insertion through-holes 25b each
include a large-diameter portion 25d positioned on a side of the
torch head 3 and a small-diameter portion 25e positioned on a side
of the torch body 5. The insulation flange 25 and torch body 5 are
fixed with respect to each other by inserting a bolt 47 through
each of the fixing bolt insertion through-holes 25b into the torch
body 5 and threadedly fitting it in each of threaded holes 11f
formed in the torch body 5. More specifically, the bolts 47 each
are threadedly fitted in each of the threaded holes 11f while being
inserted through each of the large-diameter portions 25e and
keeping a head thereof arranged therein. The flange-side bolt
insertion through-holes 25c are arranged in a manner to be
dispersed on a edge of the insulation flange 25 so as to be aligned
with the connection member-side bolt insertion through-holes 21b of
the connection member 19. Also, the flange-side bolt insertion
through-holes 25c each are so arranged that an opening thereof
defined won a side of the torch body 5 is exposed outside the
small-diameter end portion lib of the torch body 5. The flange-side
bolt insertion through-holes 25c each include a large-diameter
portion 25f positioned on a side of the torch body 5 and a
small-diameter portion 25g positioned a side of the torch head 3.
The insulation flange 25, and the first connection member half 21
and electrode support-31 are fixed with respect to each other by
inserting each of bolts 49 through two flange-side bolt insertion
through-holes 25c positioned on an upper side in FIG. 8 into the
first connection member half 21 and electrode support 31 and
threadedly fitting it in the threaded hole 31f in the electrode
support 31. More specifically, the bolt 49 is threadedly fitted in
the threaded hole 31f while extending through the small-diameter
portion 25g and the connection member-side bolt insertion
through-hole 21b of the first connection member half 21 and keeping
a head thereof received in the large-diameter portion 25f. The
insulation flange 25, and the second connection member half 23 and
nozzle support 35 are fixed with respect to each other by inserting
a bolt through each of two flange-side bolt insertion through-holes
25c positioned on a lower side in FIG. 8 into the second connection
member half 23 and nozzle support 35 and threadedly fitting it in a
threaded hole (not shown) formed in the electrode support 31. Such
arrangement permits the communication passages 21d and in-head
passages 31a to 31c to communicate with each other and the
communication holes 23d and in-head passages 35b to 35f to
communicate with each other, resulting in the connection member 19
and torch head 3 being connected to each other. Also, release of
the bolts 49 leads to separation of the connection member 19 and
torch head 3 from each other. Thus, the bolts 49 permit the torch
head 3 to be detachably connected to the torch body 5. This
facilitates replacement of the torch head 3, so that only
replacement of the torch head 3 is merely required in order to
carry out welding in conformity to a size of a pipe material, a
configuration thereof and the like. Thus, the present invention
eliminates replacement of the whole torch for powder plasma buildup
welding which is required in the prior art, to thereby facilitate
handling of the powder plasma buildup welding torch. Also, it
facilitates repairing of the torch head when it fails or breaks
down, because the torch head is detachably arranged. Further, the
in-head passages 31a to 31c and 35b to 35f each are provided on a
peripheral edge of an opening thereof with an O-ring 51, so that
communication regions between the communication holes 21d and 23d
and the in-head passages 31a to 31c and 35b to 35f each are sealed
with the O-ring 51 compressed due to tightening of the bolt 49.
[0054] The gap formation spacer member 7, as shown in FIGS. 1 and 9
to 11, includes an upper head support half 53 and a lower head
support half 55 which are combined with each other to
circumferentially surround the torch body 5. FIGS. 9 and 10 are a
plan view of the gap formation spacer member 7 and a side elevation
view thereof, respectively, and FIG. 11 is a sectional view taken
along line XI-XI of FIG. 10. The upper head support half 53 is made
of brass and includes an upper body section 57 and an upper
projection section 59. The upper body section 57 is formed into a
semi-circular shape in section so as to circumferentially surround
an upper portion of the torch body 5 and includes a groove 57a, two
threaded through-holes 57b, four bolt head arrangement grooves 57c
and four bolt insertion through-holes 57d. The groove 57a is formed
so as to extend in a direction perpendicular to a direction in
which the torch body 5 extends and formed so as to be upwardly
open. The threaded through-holes 57b each are formed through the
upper body section 57 so as to communicate with a bottom of the
groove 57a. The bolt insertion through-holes 57d each are formed so
as to communicate with an interior of each of the bolt head
arrangement grooves 57c and the lower head support half 55.
[0055] The upper projection section 59 is formed into an elongated
plate-like shape bent at a predetermined angle and includes a
supported portion 59a, an abutment portion 59b, and a connection
portion 59c for connecting the supported portion 59a and abutment
portion 59b to each other therethrough. The supported portion 59a
is arranged in the groove 57a and has an elongated through-hole 59d
extending therethrough in a thickness direction thereof. The upper
projection section 59 is fixed to the upper body section 57 by
means of two bolts threadedly fitted via the through-hole 59d in
the threaded through-holes 57b of the upper body section 57. The
through-hole 59d is formed into a length larger than a distance
between the bolts 61 and 61, to thereby be shifted with respect to
the bolts 61, to thereby vary a position of the upper projection
section 59 with respect to the upper body section 57. The abutment
portion 59b is arranged so as to be abutted at an end thereof
against an inner peripheral surface of the pipe material P.
[0056] The lower head support half 55 is made of a material
identical with that for the upper head support half 53 and includes
a lower body section 63 and a lower projection section 65. The
lower body section 63 is formed into a semi-circular shape in
section so as to circumferentially surround a lower portion of the
torch body 5 and includes a lower threaded hole 63a and four upper
threaded holes 63b. The lower threaded hole 63a is formed through
the lower body section 63 so as to be open to a position right
below a central portion of the lower body section 63. The upper
threaded holes 63b each are formed so as to be open on a side of
the upper head support half 53 and be aligned with the bolt
insertion through-holes 57d of the upper head support half 53,
respectively. The lower head support half 55 is fixed to the upper
head support half 53 by means of four bolts 67 threadedly fitted in
the upper threaded holes 63b through the bolt insertion
through-holes 57d, respectively.
[0057] The lower projection section 65 includes a projection body
65a and a ball member 65b. The projection body 65a includes a
threaded portion 65c of which an outer periphery is threaded, a
tightening operation portion 65d positioned below the threaded
portion 65c, and a ball member holding portion 65e arranged below
the tightening operation portion 65d. The projection body 65a is
fixed to the lower body section 63 in a manner to vertically
downwardly project from the lower body section 63 while keeping the
threaded portion 65c threadedly fitted in the lower threaded hole
63a of the lower body section 63. The tightening operation portion
65d is formed into a hexagonal shape in cross section so that the
threaded portion 65c may be threadedly fitted in the lower threaded
hole 63a of the lower body section 63 by means of a suitable tool
such as a wrench or the like fitted on the tightening operation
portion 65d of the lower projection section 65. The ball member
holding portion 65e is formed with a recess 65f of a hemispherical
shape which is downwardly open. The recess 65f has the ball member
65b supported therein in a rollable manner or rollably and in such
a manner that the ball member 65b is externally exposed at a part
thereof. The lower projection section 65 is so arranged that the
ball member 65b may be abutted against the inner peripheral surface
of the pipe material P. A position of the ball member 65b of the
lower projection section 65 with respect to the lower body section
63 may be suitably varied by adjusting a degree at which the
threaded portion 65c of the lower projection section 65 is fitted
in the lower threaded hole 63a of the lower body section 63. In the
illustrated embodiment, a position at which the abutment portion
59b of the upper projection section 59 and the ball member 65b of
the lower projection section 65 each are abutted against the inner
peripheral surface of the pipe material P is set so as to restrain
a variation in distance between the torch head 3 and the inner
peripheral surface of the pipe material P. The above-described
arrangement of the gap formation spacer member 7 in the illustrated
embodiment restrains a reduction in distance between the opening
33a of the convergent nozzle 33 of the torch head 3 and the inner
peripheral surface of the pipe material P due to a weight of the
torch head 3 and/or deflection of the torch body 5, to thereby
ensure that a padding W of a uniform size may be formed on the
inner peripheral surface of the pipe material P.
[0058] The deflection restraint spacer member 9 is made of brass
and, as shown in FIGS. 1 and 12 to 14, includes an upper body
support half 69, a lower body support half 71 and an abutment
member 73 which are combined with each other to circumferentially
surround the torch body 5. FIGS. 12 and 13 are a side elevation
view of the gap formation spacer member 7 and a bottom view
thereof, respectively, and FIG. 14 is a sectional view taken along
line XIV-XIV of FIG. 12. The upper body support half 69 is formed
into a semi-circular shape in section so as to circumferentially
surround an upper portion of the torch body 5 and includes four
bolt head arrangement grooves 69a and four bolt insertion
through-holes 69b. The bolt insertion through-holes 69b each are
formed so as to communicate with each of the bolt head arrangement
grooves 69a and the lower body support half 71.
[0059] The lower body support half 71 is formed into a
semi-circular shape in section so as to circumferentially surround
a lower portion of the torch body 5 and includes a groove 71a, two
lower threaded holes 71b and four upper threaded holes 71c. The
groove 71a is formed so as to extend in a direction in which the
torch body 5 extends and be downwardly open. The lower threaded
holes 71b each are formed through the lower body support half 71 so
as to communicate with a bottom of the groove 71a. The upper
threaded holes 71c each are arranged so as to communicate with the
upper body support half 69 in a manner to be aligned with each of
the bolt insertion through-holes 69b of the upper body support half
69. The lower body support half 71 is fixed to the upper body
support half 69 by means of four bolts 75 threadedly fitted in the
upper threaded holes 71c through the bolt insertion through-holes
69b, respectively. The abutment member 73 is formed into a
substantially semi-circular plate-like shape and so as to extend in
a longitudinal direction of the pipe material P. Also, the abutment
member 73 is arranged so as to vertically downwardly project from
the lower body support half 71, to thereby be abutted against the
inner peripheral surface of the pipe material P while being fitted
in the groove 71a of the lower body support half 71. Further, the
abutment member 73 includes two bolt head arrangement grooves 73a
which are formed so as to be downwardly open and two bolt insertion
through-holes 73b. The bolt insertion through-holes 73b are
arranged so as to communicate with the bolt head arrangement
grooves 73a. Also, they communicate with the lower body support
half 71 while being aligned with the lower threaded holes 71b of
the lower body support half 71. The abutment member 73 is fixed to
the lower body support half 71 by means of two bolts 77 threadedly
fitted in the lower threaded holes 71b through the bolt insertion
through-holes 73b, respectively. The above-described arrangement of
the deflection restraint spacer member 9 in the illustrated
embodiment effectively prevents the torch body 5 from leaping or
jumping in the pipe material P during buildup welding.
[0060] Referring now to FIGS. 15 to 17, another embodiment of a
torch for powder plasma buildup welding according to the present
invention is illustrated, wherein FIG. 15 is a plan view showing a
peripheral structure of a torch head of a torch of the illustrated
embodiment, FIG. 16 is a partially broken-away side elevation view
of the torch head and FIG. 17 is a bottom view of the torch head.
FIG. 16 also shows a pipe material P' to be subjected to buildup
welding. The torch of the illustrated embodiment is constructed so
as to carry out connection and separation of a torch head with
respect to a connection member by means of bolts inserted therein
from a side of the torch head. Also, in the torch of the
illustrated embodiment, an insulation flange constitutes a gap
formation spacer member. The torch of the illustrated embodiment
generally designated at reference numeral 101 is essentially
constructed in a manner similar to the torch shown in FIGS. 1 and
2. Thus, the torch 101 includes a torch head 103 and a torch body
105 for connecting a body of a welding machine (not shown) and the
torch head 103 to each other therethrough. In the torch of the
illustrated embodiment, the torch head 103 and a part of the torch
body 105 are inserted into the pipe material P'. Then, the pipe
material P' is rotated and the torch head 103 is moved in the pipe
material P', resulting in a padding W' of a spiral shape being
formed on an inner peripheral surface of the pipe material P',
leading to buildup welding. In the illustrated embodiment, the pipe
material P' is formed into an inner diameter of 38 mm. The torch
body 105, as shown in FIG. 16, includes a connection pipe 111 and
pipes 113, 115, 117 . . . arranged in the connection pipe 111 for
feeding of a DC current, gas and the like to the torch head 103. In
the illustrated embodiment, the torch body 105 is formed into a
length of about 4 m. The torch head 103 is connected to the
connection pipe 111 through a first connection member half 121 and
a second connection member half 123 cooperating with each other to
constitute a connection member 119 and through an insulation flange
125. The torch head 103 includes an electrode support 131, a
convergent nozzle 133, a nozzle support 135 for supporting the
convergent nozzle 133 therein and a head-side insulation member
137. The electrode support 131 is formed therein with a plurality
in-head passages such as an in-head passage 131b for plasma gas and
the like. The in-head passages are arranged so as to communicate
through a communication hole 121d of the first connection member
half 121 and the like with the plural pipes in the torch body 105
such as the plasma gas pipe 113 and the like, respectively. Also, a
first pipe for feeding cooling water (cooling water feed pipe)
which is one of the plural pipes constitutes a first conductive
portion electrically connected to a negative electric pole of a DC
power supply of a welding machine. This permits a current to be fed
to a bar-like electrode in the electrode support 131 through the
first cooling water feed pipe (the first conductive portion), the
first connection member half 121 and the like.
[0061] The convergent nozzle 133 is formed into a substantially
cylindrical shape of which a diameter is gradually reduced toward a
distal end of the bar-like electrode. The convergent nozzle 133 is
supported in the nozzle support 135 so as to surround the bar-like
electrode while being kept spaced from the bar-like electrode at a
predetermined interval. Also, the convergent nozzle 133 has a
shield cap 134 arranged therearound while being threadedly fitted
in the nozzle support 135.
[0062] The nozzle support 135 is formed therein with a plurality of
in-head passages such as an in-head passage 135c for feeding shield
gas, an in-head passage 135f for discharging cooling water, and the
like. The shield gas in-head passage 135c is arranged so as to
communicate through a communication hole 123d of the second
connection member half 123 to the shield gas pipe 115 of the torch
body 105. The cooling water discharge in-head passage 135f is
arranged so as to communicate through the communication hole 123d
of the second connection member half 123 with the second cooling
water discharge pipe 117 of the torch body 105. A second cooling
water feed pipe (not shown) which is one of the plural pipes
constitutes a second conductive portion electrically connected to a
positive electric pole of the DC power supply of the welding
machine. This permits a current to be fed from the positive
electric pole through the second cooling feed pipe (the second
conductive portion), second connection member half 123, nozzle
support 135 and the like to the convergent nozzle 133.
[0063] The connection member 119 is constituted by the first
connection member half 121 and second connection member half 123.
The first connection member half 121 and second connection member
half 123 has a gap or cavity formed therebetween, in which a
projection portion 137b of the head-side insulation member 137 is
fitted. The first connection member half 121 is joined to the
electrode support 131 and provided therein with a plurality of feed
holes 121a and two threaded holes 121b (FIG. 15). The feed holes
121a and threaded holes 121b each are formed so as to extend
through the first connection member half 121 in a thickness
direction thereof. The feed holes 121a each include a fit hole 121c
positioned on a side of the torch body 105 and a small-diameter
communication hole 121d positioned on a side of the torch head 103
and formed into a diameter smaller than the fit hole 121c. The fit
holes 121c of the first connection member half 121 have the plural
pipes of the torch body 105 fitted therein, respectively, and the
communication holes 121d are arranged so as to communicate with the
pipes 113 . . . , the in-head passage 131b of the electrode support
131 and the like, respectively. The second connection member half
123 is joined to the nozzle support 135 and includes a plurality of
feed holes 123a and two threaded holes 123b (FIG. 17). The feed
holes 123a and threaded holes 123b each are formed so as to extend
through the second connection member half 123 in a thickness
direction thereof. The feed holes 123a each include a fit hole 123c
positioned on a side of the torch body 105 and a communication hole
123d positioned on a side of the torch head 103 and formed into a
diameter smaller than the fit hole 123c. The fit holes 123c have
the plural pipes 115, 117 . . . of the torch body 105 fitted
therein, respectively, and the communication holes 123d are
arranged so as to communicate with the pipes 115, 117 . . . of the
torch body 105, the in-head passages 135c, 135f, and the like,
respectively.
[0064] In the powder plasma buildup welding torch of the
illustrated embodiment, as shown in FIG. 15, the electrode support
131 of the torch head 103 is formed with a plane 131g facing a
front of the powder plasma buildup welding-torch (on a left side in
FIG. 15) and two bolt insertion through-holes 131h open to the
plane 131g. The electrode support 131 of the torch head 103 is
fixed to the first connection member half 121 of the connection
member 119 by means of bolts 149A inserted through the bolt
insertion through-holes 131h of the electrode support 131 of the
torch head 103 and threadedly fitted in the threaded holes 121b of
the first connection member half 121. Also, as shown in FIG. 17,
the nozzle support 135 of the torch head 103 is formed with a plane
133b facing the front of the powder plasma buildup welding torch
(on a left side in FIG. 17) and two bolt insertion through-holes
133c open to the plane 133b. The nozzle support 135 of the torch
head 103 is fixed to the second connection member half 123 by means
of bolts 149B inserted through the bolt insertion through-holes
133c and threadedly fitted in the threaded holes 123b of the second
connection member half 123. Such fixing between the nozzle support
135 and the second connection member half 123 cooperates with the
above-described fixing between the electrode support 131 and the
first connection member half 121 to carry out fixing between the
torch head 103 and the connection member 119.
[0065] The insulation flange 125, as shown in FIGS. 15 to 18, is
formed into a cylindrical configuration having a diameter (36 mm)
smaller than the-above-described inner diameter (38 mm) of the pipe
material P'. FIG. 18 is a plan view of the insulation flange 125
which is viewed from a side of the torch body 105. The insulation
flange 125 is abutted at a lower end thereof against the inner
peripheral surface of the pipe material P'. Such arrangement
permits the insulation flange 125 to act as a gap formation spacer
member. The insulation flange 125 has a through-hole 125a formed
therein so as to extend through a central portion thereof, in which
the plural pipes 113, 115, 1171 . . . are arranged. The central
through-hole 125a includes a large-diameter portion 125b and a
small-diameter portion 125c smaller in diameter than the
large-diameter portion 125b, between which a stepped portion 125d
is formed. The large-diameter portion 125b has the connection pipe
111 of the torch body 105 fitted therein.
[0066] The insulation flange 125 is formed with three first bolt
insertion through-holes 125e open to the stepped portion 125d and
four second bolt insertion through-holes 125f. The first bolt
insertion through-holes 125e, as shown in FIGS. 15 and 17, each
include a large-diameter portion 125g positioned on a side of the
torch head 103 and a small-diameter portion 125h positioned on a
side of the torch body 105. The insulation flange 125 and torch
body 105 are fixed to each other by means of bolts 147A inserted
from the first bolt insertion through-holes 125e into the torch
body 105 and threadedly fitted in threaded holes 111f formed in the
torch body 105. More specifically, the bolts 147A each are
threadedly fitted in each of the threaded holes 111f while being
kept inserted through the small-diameter portion 125h of the first
bolt insertion through-hole 125e and keeping a head of the bolt
arranged in the large-diameter portion 125g.
[0067] The second bolt insertion through-holes 125 each include a
large-diameter portion 125i positioned on a side of the torch body
105 and a small-diameter portion 125j positioned on a side of the
torch head 103. The insulation flange 125 and the first connection
member half 121 of the connection member 119, as shown in FIG. 15,
are fixed to each other by means of bolts 147B inserted through the
second bolt insertion through-holes 125f positioned at an upper
portion of the insulation flange 125 into the first connection
member half 121 and threadedly fitted in threaded holes 121e formed
in the first connection member half 121, respectively. More
specifically, the bolts 147B each are arranged so as to extend
through the small-diameter portion 125j of the second bolt
insertion through-hole 125f and threadedly fitted in each of the
threaded holes 121e of the first connection member half 121 while
positioning a head thereof in the large-diameter portion 125i.
Also, as shown in FIG. 17, the insulation flange 125 and the second
connection member half 123 of the connection member 119 are fixed
to each other by means of bolts 147C inserted from the second bolt
insertion through-holes 125f positioned at a lower portion of the
insulation flange 125 into the second connection member half 123
and threadedly fitted in threaded holes 121f formed in the second
connection member half 123. More specifically, the bolts 147C each
are inserted through the small-diameter portion 125j of the second
bolt insertion through-hole 125f and threadedly fitted in each of
the threaded holes 121f of the second connection member half 123
while positioning a head thereof in the large-diameter portion
125i. Thus, the insulation flange 125 and connection member 119 are
fixed to each other due to such fixing between the insulation
flange 125 and the first connection member half 121 and that
between the insulation flange 125 and the second connection member
half 123.
[0068] Referring now to FIGS. 19 to 21, a deflection restraint
spacer member incorporated in a further embodiment of a torch for
powder plasma buildup welding according to the present invention is
illustrated, wherein FIG. 19 is a plan view of the spacer member,
FIG. 20 is a side elevation view thereof and FIG. 21 is s sectional
view taken along line XXI-XXI. The deflection restraint spacer
member generally designated at reference numeral 109 includes a
first body support half 169 and a second body support half 171
which are combined with each other to circumferentially surround a
torch body. The deflection restraint spacer member 109 is formed
into a cylindrical shape like a straw bag which is expanded at a
central portion thereof. The central expansion thus formed is
formed into an outer diameter smaller than an inner diameter of a
pipe material and an inner diameter which permits the torch body to
be tightly fitted therein. The first body support half 169 is
formed into a semi-circular shape in section so as to
circumferentially surround an upper portion of the torch body and
provided thereon with four bolt head arrangement grooves 169a and
four bolt insertion through-holes 169b. The bolt insertion
through-holes 169b are formed so as to be open to the bolt head
arrangement groove 169a and second body support half 171.
[0069] The second body support half 171 is formed into a
semi-circular shape in section so as to circumferentially surround
a lower portion of the torch body and provided with four threaded
holes 171c. The threaded holes 171c are arranged so as to be open
to the first body support half 169 while being respectively aligned
with the bolt insertion through-holes 169b of the first body
support half 169. The second body support half 171 is fixed to the
first body support half 169 by means of four bolts 175 inserted
through the bolt insertion through-holes 169b and threadedly fitted
in the threaded holes 171c of the second body support half 171. In
the deflection restraint spacer member 109 thus constructed, the
second body support half 171 is abutted at a lower end thereof
against an inner peripheral surface of a pipe material, to thereby
prevent leaping of the torch body. The gap formation spacer member
constituted by the insulation flange 125 shown in FIGS. 15 to 18
and the deflection restraint spacer member 109 shown in FIGS. 19 to
21 may be suitably used for a powder plasma buildup welding torch
which carries out buildup welding on an inner peripheral surface of
a pipe material having a relatively small inner diameter (about 40
mm or less).
[0070] As can be seen from the foregoing, the powder plasma buildup
welding torch according to the present invention is so constructed
that the torch head is detachably or replaceably connected to the
torch body. Such construction permits welding to be attained in
conformity to any size of a pipe material to be subjected to
welding, any configuration thereof and the like. Thus, the present
invention facilitates application of the torch to buildup welding
while eliminating replacement of the whole powder plasma buildup
welding torch required in the prior art. Also, when any trouble
occurs in the torch head, torch head may be readily repaired
because it is detachably mounted on the torch body.
[0071] Also, arrangement of the gap formation spacer member in the
torch effectively prevents a variation in distance between the
opening of the convergent nozzle of the torch head and an inner
peripheral surface of a pipe material subjected to welding due to a
weight of the torch head and/or deflection of the torch body, to
thereby ensure that a padding of a uniform size is satisfactorily
formed on the inner peripheral surface.
[0072] Further, arrangement of the deflection restraint spacer
member prevents leaping of the torch body.
[0073] While preferred embodiments of the invention have been
described with a certain degree of particularity with reference to
the drawings, obvious modifications and variations are possible in
light of the above teachings. It is therefore to be understood that
within the scope of the appended claims, the invention may be
practiced other wise than as specifically described.
* * * * *