DESCRIPTION
PRODUCTION MANAGEMENT METHOD
FOR STEEL TUBES AND PIPES
TECHNICAL FIELD
[ooo 11
The present invention relates to a production management method
for steel tubes and pipes and, more particularly, to a production
management method for steel tubes and pipes, in which method a steel
tube or pipe is produced through a plurality of production processes.
BACKGROUND ART
[00021
For steel tubes and pipes produced through a plurality of
production processes, the treatment in each process must be performed
reliably under the predetermined production conditions, and therefore
management must be carried out so that the actual goods of steel tubes
and pipes can be identified. In a process such as a heat treatment
process in which a plurality of steel tubes and pipes are treated at the
same time, the identification management of steel tubes and pipes must
be carried out in lot units, and in a process such as a grinding process and
a nondestructive inspection process in which steel pipes are treated on a
one pipe basis, the identification management of steel tubes and pipes
must be carried out on a pipe basis. Also, at the same time, it is desired
to record the production information and quality information according to
each steel tube or pipe in each process and to manage the production
history.
[00031
In particular, for a steel pipe for nuclear power plant use, the
production history data are required to be retained for a long time period.
For example, a cold finished steel pipe is produced through a plurality of
production processes such as rolling, heat treatment, grinding, and
inspection. And in the production processes of the steel pipe after the
heat treatment process, various production histories such as heat
treatment temperature, amount of grinding and result of nondestructive
inspection must be managed.
[00041
Conventionally, as a method for strictly managing these production
histories, there have been carried out a method in which an annexed
table is attached to a pallet for moving materials, a method in which a
bar code manufactured by using paper is inserted in a steel pipe, a
method in which a bar code is stuck to a material-protective sheet, and
the like method. In these management methods, however, much labor
has been spent because production management is carried out on a pipe
basis in all the processes.
[00051
For a printed wiring board used in an electric circuit, the
management has been carried out manually, for example, by using a
name tag, label, or process control sheet on which an item number
consisting of letters of the alphanumeric characters is printed. In Patent
Document 1, however, there has been proposed a method in which, in the
manufacturing process of printed wiring board, a code such as a bar code
or matrix code is formed from a conductor by using a printing means,
etching means, or the like means, and in a subsequent process, the code is
read by a commercially-available code reader.
[0006]
In Patent Document 2, it is pointed out that, in the control of
thread cutting process of an oil-well steel pipe produced through
complicated processes of heating, rolling, finishing, heat treatment,
inspection, and the like, a method in which marking is performed on the
outer surface of steel pipe has a possibility of disappearing of marking,
and a method in which imprinting is performed on the inner or outer
surface of steel pipe has a problem of flaw generation on the steel pipe,
incapability of imprinting on the inner surface of a small-diameter steel
pipe, or the like. As a method for solving these problems, there has been
proposed a management method in which an IC tag having the
production information stored therein is buried in the end face of a
protector mounted in the pipe end portion to protect the pipe body or the
thread part.
[00071
In Patent Document 3, as a method for identification management
of steel pipe, there has been proposed a method in which an IC tag is
mounted on a lightweight holder, and the holder is stuck to the inner
surface of steel pipe via a bonding medium, because in the conventional
method in which a permanent magnet is used to attract an IC tag stuck
to a resin plate to the inner surface of pipe, the IC tag may come off by a
shock.
[00081
Also, some methods in which markings are performed directly on
steel tubes and pipes by using laser processing have been proposed so far.
[00091
Patent Document 4 proposes a marking method in which a laser
beam is applied to the outer peripheral surface of a metallic pipe by using
a scanning mirror to draw letters, figures, and the like having a depth of
0.1 pm or smaller because much labor is required in the conventional lot
control method in which an identification tag on which the lot number is
written down is tied up with a nylon rope.
[00101
Patent Document 5 proposes a laser marking method of a bar code,
in which thin lines are formed on the surface by scanning a laser beam,
and a plurality of the thin lines are arranged to form a thick line,
whereby a thermal attack and chemical change in material caused by the
formation of thick line are reduced. In this method, a laser beam is
applied while a steel pipe is rotated, and thereby a depth of about 10 to 50
pm is formed around the entire circumference of pipe.
Loo 111
Patent Document 6 proposes a fuel cladding tube having an
identification code, in which the identification code such as a bar code,
letters, and codes consisting of a smooth surface is formed on the fuel
cladding tube that has fine unevenness on the outer surface thereof and
is used for a fuel rod, and irregular reflection is made incident on the
material surface and regular reflection is made incident in the
identification code section by carrying out control so that the lighting
angle and the imaging angle are different from each other, whereby the
contrast of bright and dark between the material surface and the
identification code section is increased.
[oo 121
Patent Document 7 discloses that for a nuclear fuel rod formed
from a Zircaloy alloy, an identification code consisting of a laser beam
machined bar code is read with an optical means. The invention
described in Patent Document 7 relates to a nondestructive measurement
method of a heat-affected zone produced by the laser beam machining,
and this Document describes that even if the depth of laser beam
machining is 0.05 mm, a heat-affected depth of about 0.5 mm remains.
[OO1 31
Patent Document 8 discloses a technique in which in laser marking
of a nuclear fuel cladding tube, the laser power is made low, the
unevenness of a mark section or a space section other than the mark
section is melted by laser heat, and the difference in reflectance between
the mark section and the space section is increased, whereby the
identification performance is improved because if an uneven portion is
present on the surface of fuel cladding tube on account of oxidation, a
change in metal crystal grains, and the like caused by machining heat,
there arise a problem of a decrease in cladding capability of cladding tube
and the like problems.
LIST OF PRIOR ART DOCUMENTS
PATENT DOCUMENT
[00141
Patent Document 1: JP5-75222A
Patent Document 2: JP2008-250714A
Patent Document 3: JP2009-301391A
Patent Document 4: JP6-114576A
Patent Document 5: JP10-6045A
Patent Document 6: JPll-23756A
Patent Document 7: JP3-72296A
Patent Document 8: JP2000-317656A
DISCLOSURE OF THE INVENTION
PROBLEMS TO BE SOLVED BY THE INVENTION
[OO1 51
The method disclosed in Patent Document 1 relates to the
identification management method of a printed wiring substrate for an
electric circuit, and cannot be applied to a steel pipe that does not
undergo a printing or etching process as a production process.
[OOI~I
The method disclosed in Patent Document 2 is such that a hole is
formed on the pipe end face, and an IC tag is mounted and buried in the
hole. However, it is difficult to apply this method to a small-diameter
and thin-wall thickness steel pipe with a wall thickness of about 1 mm,
such as a steel pipe for nuclear power plant use.
[OO1 71
The method disclosed in Patent Document 3 is a method in which
after an IC tag has been mounted on a lightweight holder, the holder is
stuck to the inner surface of steel pipe, and the production information
stored in the IC tag is controlled via an antenna. However, problems are
that not only the holder cannot be stuck to the inner surface of a smalldiameter
pipe but also in the case where an adhesive is used on a steel
pipe for nuclear power plant use, the components of the adhesive are
regulated.
[OOI~I
The method disclosed in Patent Document 4 relates to a marking
method in which an identification management code such as letters and
figures is drawn by a laser beam, and this Document does not at all
describe a technique concerning the subsequent reading of code. In
particular, the reading of letters and figures is unfavorable because
misreading occurs easily. Further, in the case where many pieces of
information are machined by means of letters and figures, the machining
time increases, and heat generated in machining is remarkable.
[00191
The method disclosed in Patent Document 5 is a laser marking
method of bar code, in which thin lines are arrangedly formed while a
steel pipe is rotated at its site to form a thick line. However, a pipe
rotating apparatus for marking must be installed newly, so that the
equipment cost increases. In particular, for a longer-length pipe, an
enormous cost is required. Also, for a bar code, when the amount of
identified information is increased, the number of machined lines
increases. Therefore, this method has a problem of significant heat
generated ingenerated in machining.
[00201
In the method disclosed in Patent Document 6, in the case where
an identification code consisting of letters and codes is used, misreading
may occur when they are read. Also, in the case where a bar code is
used as well, there arises a problem of heat generated in machining as
described above.
[00211
The method disclosed in Patent Document 7 relates to
nondestructive measurement of a heat-affected zone produced by the
laser beam machining, and this Document does not describe the
prevention of deterioration caused by thermal attack.
[00221
In the method disclosed in Patent Document 8, the unevenness of a
mark section or a space section other than the mark section is melted by
laser, whereby the identification performance of bar code is improved.
However, the steel pipe used in a nuclear power plant is productioncontrolled
so as to have a surface roughness of 1 pm or smaller
(practically, 0.5 pm or smaller), and the inherent roughness is very small.
Therefore, even if fine unevenness is melted by laser beam machining,
the surface roughness rather increases, so that it is difficult to improve
the identification performance. In the result of verification accomplished
by the present inventors, a special difference has not also been recognized.
Further, the machining time required for melting the unevenness
becomes long, which presents a problem of a decrease in productivity.
roo231
As described above, the methods disclosed in Patent Documents 1
to 3 are less liable to be applied to a small-diameter and thin-wall
thickness steel tube such as a heat exchanger tube for steam generators,
and also in the methods disclosed in Patent Documents 4 to 7, a problem
of heat generated in machining is left unsolved. Further, it is difficult to
apply the method disclosed in Patent Document 8 to steel tubes and pipes
for nuclear power plant use.
[00241
Accordingly, an objective of the present invention is to provide a
method in which actual goods identification can be accomplished reliably
on a pipe basis without causing serious thermal attack on the steel tubes
and pipes.
MEANS FOR SOLVING THE PROBLEMS
[00251
The present inventor examined a method for properly carrying out
the identification management of steel tubes and pipes produced through
a plurality of production processes and conducted studies earnestly, and
resultantly obtained the following findings.
[0026] -- (A) In order to identify steel tubes and pipes on a pipe basis, an
identification codes should be machined directly on the steel tubes and
pipes by using a laser beam. If letters, symbols, or the like are used as
the identification code, misreading may occur. Therefore, a code should
be used. However, for a one-dimensional bar code, if the amount of
information to be identified is large, a laser beam machined area
increases, and there arises a problem of heat generation resulting firom
the increase in laser beam machined area. Therefore, there is used a
two-dimensional matrix code in which the equivalent amount of
information can be machined in a time period of one-fourth or less of the
time period of the one-dimensional bar code.
[00271
(B) In reading the matrix codes machined on the surface of the steel
tubes and pipes conveyed while rotating, if an image is captured by using
an area sensor type camera, it is very difficult to regulate and control the
shutter releasing timing. Also, in the case where a certain section is
photographed continuously and the data thereof are analyzed, the
amount of data becomes unfavorably enormous. Further, the matrix
code machined on a curved surface poses a problem of incapability of
reading because depending on the size, in imaging with the area sensor
type camera, the whole surface is not in focus. Therefore, a linear sensor
type camera is used for imaging.
Lo0281
The present invention has been completed on the basis of the above
findings, and involves the production management methods for steel
tubes and pipes described in the following (1) to (5).
[00291
(1) A production management method for steel tubes and pipes
produced through a plurality of production processes, including:
a step of machining a matrix code, which encodes tube or pipe
information, in a tube or pipe end by a laser beam so that the central
angle of width of the matrix code in a circumferential direction of the tube
or pipe is 30" or smaller; and
a step of reading the matrix code automatically by using a linear
sensor type camera, wherein
through reading the matrix code, the production history is managed
by identifying and recording the production information and quality
information corresponding to each steel tube or pipe for each tube or pipe
number, and
the tube or pipe information is retrievable as necessary.
[00301
(2) The production management method for steel tubes and pipes
according to (I), wherein in the step of reading the matrix code
automatically by using the linear sensor type camera, the feed skew angle
of steel tube or pipe is set at 16" or smaller.
[00311
(3) The production management method for steel tubes and pipes
according to (1) or (2), wherein the method further includes a step of
reading the matrix code manually by using an area sensor type camera.
[00321
(4) The production management method for steel tubes and pipes
according to any one of (1) to (3), wherein the method is a production
management method for a heat exchanger tube for steam generators.
[00331
(5) The production management method for steel tubes and pipes
according to (4), wherein the production processes of the steel tube
include a grinding process, and in the grinding process, the method
further includes a step of controlling a grinding head retraction to avoid
grinding the tube end portion on which the matrix code is machined.
ADVANTAGEOUS EFFECTS OF THE INVENTION
Lo0341
According to the present invention, since the matrix code is
machined directly on the end portion of the surface of the steel tube or
pipe, actual goods identification can be accomplished reliably on a pipe
basis without causing a thermal attack on the steel tube or pipe. Also,
when the steel tubes and pipes undergo a plurality of subsequent
production processes, the matrix codes are read automatically as
appropriate, whereby the production information and quality information
corresponding to each steel tube or pipe can be recorded, and the
production history can be managed easily. Therefore, the present
invention is especially suitable as a production management method for a
heat exchanger tube for steam generators whose production process is
complicated.
BRIEF DESCRIPTION OF THE DRAWINGS
[00351
[Figure 11 Figure 1 is a diagram for explaining one example of the
production processes for a steel pipe.
[Figure 21 Figure 2 is a schematic view showing one example of a step of
machining a matrix code.
[Figure 31 Figure 3 is a schematic view showing one example of a step of
automatically reading a matrix code.
[Figure 41 Figure 4 shows imaging examples of matrix codes obtained by
using a linear sensor type camera.
[Figure 51 Figure 5 shows imaging examples of matrix codes obtained by
using an area sensor type camera.
[Figure 61 Figure 6 is a diagram for explaining one example of the
production processes for a steel pipe in and after an inspection process.
MODE FOR CARRYING OUT THE INVENTION
[00361
The production management method for steel tubes and pipes
according to the present invention is a production management method
for steel tubes and pipes produced through a plurality of production
processes, and includes a step of machining a matrix code and a step of
reading the matrix code automatically. In addition to the above steps,
the production management method may include a step of reading the
matrix code manually and/or a step of controlling a grinding head
retraction to avoid grinding the tube or pipe end portion on which the
matrix code is machined. In the following, the production method for
steel tubes and pipes and each step in the production management
method are described in detail.
[00371
1. Production process of steel tubes and pipes
The production process of steel tubes and pipes to which the
production management method of the present invention is applied is not
specifically limited. In general, however, steel tubes and pipes undergo
a heat treatment process, a grinding process, and an inspection process,
and thereafter the steel tubes and pipes are packaged and shipped.
Since the throughput of each process is different, the production process
includes a batch treatment, such as heat treatment, in which
simultaneous treatment is performed in lot units, and a one pipe
treatment, such as grindinghuffing and inspection, in which treatment is
performed on a pipe basis. Also, a plurality of pieces of equipment have
been introduced in the same process according to the throughput of
equipment. Since the production information and quality information
requiring the management of production history are different depending
on the production process, an identification number for identifying and
managing the steel tubes and pipes when the steel tubes and pipes
undergo each production process is necessary.
[00381
As shown in Figure 1, the production process of a heat exchanger
tube for steam generators is further complicated. After first heat
treatment, grinding is performed to remove flaws induced by heat
treatment or bend straightening. Also, to improve corrosion resistance,
second heat treatment is performed as a sensitization treatment, and
subsequently, slight buffing is generally performed immediately before
the product inspection. At this time, the first heat treatment and second
heat treatment are performed by batch treatment, and the grinding,
buffing and inspection are performed by one pipe treatment. The heat
treatment conditions in the heat treatment process, and the grinding and
buffing amount in the grinding and buffing process are objects of
management of production history as the production information, and the
inspection result in the inspection process is an object of management of
production history as the quality information.
[00391
2. Step of machining matrix code
The matrix code is encoded tube or pipe information for identifjring
and managing steel tubes and pipes, and is machined in the end portion
of the tube or pipe by using a laser beam. The tube or pipe information
may be only the identification number of steel tube or pipe, or may be the
identification number and predetermined production conditions. If the
machining location is in the range of within 200 mm from the tube or pipe
end, which is a cutting margin, the thermal attack resulting from code
machining can desirably be avoided completely.
[100401
By machining the tube or pipe end portion, which is a cutting
margin, the thermal attack on the product can be avoided completely;
however, even the heat generation in the tube or pipe end portion may
sometimes cause trouble as described below.
[00411
As described above, usually, the production process of steel tubes
and pipes includes an outer surface grinding process, and grinding of
about 80 to 100 pm is performed. During grinding, grinding water is
generally used. By using the grinding water, the grinding amount can
be assured, the grinding powder can be prevented from scattering, and
the noise can be reduced. At this time, in order to prevent the grinding
water from intruding into the tube or pipe inner surface from the end
portion, an end plug is inserted. As the end plug, for example, a felt-like
cylinder is used, and this cylinder is inserted about 100 mm deep from
both of the tube or pipe ends. Therefore, if the heat generation in the
end portion caused by the laser beam machining is excessive, smoke is
generated from the end plug, or further the end plug burns. Therefore,
especially, the tube or pipe inner surface may be contaminated by
combustion impurities.
LO0421
As given in Table 1, in the case where a bar code is machined, the
machining time is long, and the material temperature rises after
machining, so that smoke is generated from the end plug. On the other
hand, in the case where a matrix code is machined, the machining time
can be shortened, so that it is found that the trouble of end plug caused
by heat generation does not occur.
Lo0431
[Table 11
Lo0441
The location in production process in which the step of machining
the matrix code is provided is not specifically limited. However, since in
and after the grinding process in which one pipe treatment is started, the
management of production information and quality information on a pipe
basis is necessary as shown in Figure 1, it is preferable that the matrix
code be machined after or simultaneously with the grinding.
Lo0451
In this case, the code machining step can be performed, for example,
pursuant to the procedure as shown in Figure 2. A steel pipe 1 charged
onto an inlet table 11 of the grinding process is conveyed while being
rotated, and passes successively through an inlet conveyor 12, a grinding
apparatus 13, and an outlet conveyor 14. The grinding amount at this
time is not defined especially. However, it is preferable that grinding of
about 100 pm in outside diameter be performed. The ground steel pipe 1
comes to a standstill on an outlet table 15, and the matrix code is
machined by using a laser beam machine 16. At this time, the pipe
information is given, and also the production information concerning the
outer surface grinding amount corresponding to each steel pipe is
Table 1
Aenfied cpt luogn
none
none
none
fuming
fum~ng
fumlng
fuming
fuming
fuming
Readability
0
0
A
0
0
0
A
A
n
Temperature
CC)
Room temp
Roomtemp
Room temp.
145
165
190
120
140
165
1
2
3
4
5
6
7
8
9
Code
size
2% lOmm
2x1 Omm
2* 1 Omm
width: 3mm
width: 4mm
width: 5mm
width: 3mm
width. 4mm
width 5mm
Machining
time (s)
40
30
25
155
190
220
125
155
190
Machining
depth (Pm)
7
5
3
7
7
7
5
5
5
Codes
Matrix code
Matrii code
Matrix code
Bar code
Bar code
Bar code
Bar code
Bar code
Bar code
recorded. With respect to the conveying direction, the matrix code may
be machined on the front end side of steel pipe or on the rear end side.
Alternatively, the matrix code may be machined on both end sides of steel
pipe.
[00461
3. Step of automatically reading matrix code
The matrix code having been machined on the steel tube or pipe
surface by the above procedure is read automatically as appropriate when
the steel tube or pipe passes through each production process. Thereby,
the actual goods identification of steel tube or pipe is accomplished, and
the tube or pipe information is retrieved as necessary. Also, at the same
time, the production information and quality information corresponding
to each steel tube or pipe are recorded, whereby the production history
can be managed.
Lo0471
The automatic reading can be performed before all or some of the
production processes. Figure 3 is a schematic view showing a step of
automatically reading the matrix code immediately before the buffing
process. The steel pipe 1 placed on the inlet side of a buffing apparatus
21 is conveyed while being rotated by transfer rollers 22. At this time,
the code can be read by picking up the image by using a linear sensor
type camera 23 installed above the rotating steel pipe 1. The matrix
code has been machined in the minimum area in some portion in the
circumferential direction of steel pipe. Therefore, when the linear sensor
type camera 23 used for imaging is fixedly arranged, the steel pipe must
be rotated to capture image around the entire circumference of pipe.
Since the buffing process is carried out while the steel pipe is rotated, the
linear sensor type camera 23 is desirably arranged immediately before
the buffing process.
[00481
As shown in Figure 3, the automatic reading using the linear
sensor type camera 23 can be performed by imaging for a certain time
period when the pipe end of the conveyed steel pipe is detected by a pipe
end detection sensor 24. The imapng time period is not specifically
limited. However, it is preferable that the imaging time period be made
a short time period of within 2 seconds, which is a time period in which
the pipe end portion passes through, and the image information to be
processed be made at a minimum.
[00491
Since the steel pipe has a feed skew angle because of advancing
while being rotated, the image obtained by the linear sensor type camera
is distorted as shown in Figure 4. However, it has been found that if the
skew angle is at least 16' or smaller, the code can be automatically read
almost reliably.
[00501
4. Step of manually reading matrix code
In some cases, it is desired to add information on only a specific
steel tube or pipe, such as a steel pipe that is judged to be unacceptable in
the inspection process, midway in the production process. At this time,
if the tube or pipe information is manually inputted by operating, for
example, a keyboard, there may be a mistake such as an input error.
Therefore, it is preferable that the matrix codes machined on the surfaces
of the tubes and plpes be read manually by using a camera.
[00511
The manual reading of the matrix code is performed on the
stationary steel tube or pipe. Therefore, an area sensor type camera is
preferably used. For the matrix code machined on a curved surface, it is
impossible that the whole surface is brought into focus depending on the
size, so that the matrix code machined on a curved surface cannot be read
in some cases. However, as the result of reading test in which matrix
codes with various widths were machined on steel pipes having various
diameter, it has been found, as shown in Table 2, that if the central angle
of the width of the matrix code in a circumferential direction of the pipe is
30" or smaller, the matrix code can be read by using the area sensor type
camera. In the automatic reading using the linear sensor type camera,
all of the matrix codes having been tested could be read.
[00521
[Table 21
Also, as shown in Figure 5, when the steel pipe is photographed
with a camera, the peripheral side surface portion of steel pipe is
brightened by illumination, and the reading of this portion has been
difficult. On the other hand, it has been found that the central portion is
darkened, but in this portion, the unevenness of illuminance is little, so
that photographing can be performed properly. If the central angle of
the width of the matrix code is 30" or smaller as described above, the
matrix code can be kept within the range in which the unevenness of
illuminance is little. Also, as shown in Figure 5, even in the case where
the matrix code was photographed slantwise, the reading was possible.
In the present invention, therefore, the central angle of the width of the
matrix code to be machined is set at 30" or smaller.
[00541
The manual reading of matrix code using the area sensor type
camera can be performed, for example, in the inspection process. Figure
6 is a diagram showing the details of each process in and after the
inspection process up to shipping. After the finish of the buffing,
nondestructive inspection such as ultrasonic testing (UT) or eddy current
testing (ET) is carried out, and further subsequently, visual surface
inspection is carried out. As shown in Figure 6, in the nondestructive
inspection process, the inspection result corresponding to each steel pipe
is preferably recorded by automatic reading. In contrast, in the visual
surface inspection process, to strengthen actual goods identification, all
steel pipes preferably undergo actual goods confirmation by manual
reading.
[00551
A steel pipe judged to be unacceptable by nondestructive inspection
or visual surface inspection is recorded as an unacceptable product by
manual reading, thereafter stopping being conveyed to the next process,
and is treated as an unacceptable product.
[00561
As shown in Figure 6, subsequently, the steel pipe can be subjected
to bending work as necessary. At this time, to record the curvature
information assigned to each steel pipe, manual reading is preferably
performed before the bending work process. After the bending work,
inner surface ET is performed again and dimensional inspection is
carried out, and thereafter visual surface inspection is further carried out.
In the inner surface ET process and the dimensional inspection process,
the inspection result corresponding to each steel pipe is preferably
recorded by automatic reading. In contrast, in the visual surface
inspection process, to strengthen actual goods identification, all steel
pipes preferably undergo actual goods confirmation by manual reading.
A steel pipe judged to be unacceptable by the inspection after the bending
work is recorded as an unacceptable product by manual reading in the
same manner as described above, thereafter stopping being conveyed to
the next process, and is treated as an unacceptable product.
LO0571
The steel pipe having undergone the inspections is shipped after
being packaged. In packaging, package position information is recorded
by manual reading.
[00581
5. Step of controlling a grinding head retraction
In the production process of the heat exchanger tube for steam
generators, the machining of matrix code is preferably performed after
the grinding. However, since the buffing is further performed
subsequently, the disappearance of code caused by the buffing process
must be avoided.
[00591
In the buffing process, there is preferably provided a control step in
which the passing-through of the tube or pipe end portion, in which the
matrix code has been machined, is detected, and the grinding head is
retracted. For this purpose, control is carried out so that the tube or
pipe end portion is not ground. However, since the tube or pipe end
portion is a cutting margin, there does not arise a problem of remaining
flaw.
[10060]
The above is an explanation of the production management method
of the present invention, given especially by taking the production process
of the heat exchanger tube for steam generators as an example. The
embodiment of the present invention is not limited to the production
management of the heat exchanger tube for steam generators, and can be
applied to the production management of various kinds of steel tubes and
pipes.
INDUSTRIAL APPLICABILITY
Lo06 11
According to the present invention, since the matrix code is
machined directly on the end portion of the surface of the steel tube or
pipe, actual goods identification can be accomplished reliably on a pipe
basis without causing a thermal attack on the steel tube or pipe. Also,
when the steel tubes and pipes undergo a plurality of subsequent
production processes, the matrix codes are read automatically as
appropriate, whereby the production information and quality information
corresponding to each steel tube or pipe can be recorded, and the
production history can be managed easily. Therefore, the present
invention is especially suitable as a production management method for a
heat exchanger tube for steam generators whose production process is
complicated.
REFERENCE SIGNS LIST
[00621
1. steel pipe
11. inlet table
12. inlet conveyor
13. grinding apparatus
14. outlet conveyor
15. outlet table
16. laser beam machine
21. buffing apparatus
22. transfer roller
23. linear sensor type camera
24. pipe end detection sensor
We claim:
1. A production management method for steel tubes and pipes
produced through a plurality of production processes, including:
a step of machining a matrix code, which encodes tube or pipe
information, in a tube or pipe end by'a laser beam so that the central
angle of width of the matrix code in a circumferential direction of the tube
or pipe is 30" or smaller; and
a step of reading the matrix code automatically by using a linear
sensor type camera, wherein
through reading the matrix code, the production history is managed
by identifying and recording the production information and quality
information corresponding to each steel tube or pipe for each tube or pipe
number, and
the tube or pipe information is retrievable as necessary.
2. The production management method for steel tubes and pipes
according to claim 1, wherein in the step of reading the matrix code
automatically by using the linear sensor type camera, the feed skew angle
of steel tube or pipe is set at 16" or smaller.
3. The production management method for steel tubes and pipes
according to claim 1 or 2, wherein the method further includes a step of
reading the matrix code manually by using an area sensor type camera.
4. The production management method for steel tubes and pipes
according to any one of claims 1 to 3, wherein the method is a production
management method for a heat exchanger tube for steam generators.
5. The production management method for steel tubes and pipes
according to claim 4, wherein the production processes of the steel tube
include a grinding process, and in the grinding process, the method
further includes a step of controlling a grinding head retraction to avoid
grinding the tube end portion on which the matrix code is machined.