Method for manufacturing cast pipes and apparatus for marking cast pipes

Abstract

The present invention provides a method for manufacturing a cast pipe that allows for the display of a large amount of information, including manufacturing information, on the axial end face of the receiving end of the cast pipe, even in a limited space, and that allows for the reading of such information without misinterpretation. [Solution] The method for manufacturing the pipe 99 includes a pipe casting step SA1 in which a pipe 99 having a flange-shaped socket end 90 on one axial end is formed by casting, and an engraving step SA3 in which a two-dimensional code X containing at least manufacturing information of the pipe 99 is engraved on the axial end face 90a of the socket end 90 by laser light L emitted from a laser light emission device 6.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a cast pipe having a flange-shaped receiving end portion on one end side in the axial direction, and a cast pipe marking device for marking manufacturing information on an end surface of the receiving end portion.

Background Art

[0002] A method of forming a management number of a pipe to be cast as a concavo-convex symbol on an end surface of a receiving end portion of the pipe is known. For example, Patent Document 1 discloses a method of forming a management number formed by concavo-convex characters on an outer end surface of a flange of a receiving port of a cast iron pipe cast using a core for receiving port casting on which recesses for forming the management number formed by concavo-convex characters are engraved. In Patent Document 1, the management number formed by the concavo-convex characters is photographed with a camera to obtain image data, and the destination of shipment is linked to each management number before shipment, and the manufacturing history and destination of shipment of each cast iron pipe are managed by the management number.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, the space on the axial end surface at the receiving end portion of the cast pipe is limited. Therefore, when it is desired to display a lot of information such as manufacturing information of the cast pipe on the axial end surface of the receiving end portion of the cast pipe, there is a possibility that all the information cannot be displayed on the axial end surface of the receiving end portion of the cast pipe by symbols (concavo-convex symbols) expressed by the concavo-convex shape as in Patent Document 1.

[0005] Furthermore, depending on the casting conditions, the axial end face of the socket end may be formed roughly, and some of the formed uneven symbols may be missing. In this case, there is a possibility of misinterpretation when reading information including manufacturing information from the uneven symbols using equipment or visual inspection.

[0006] Therefore, there is a need for a method of manufacturing a cast pipe that can display a large amount of information, including the manufacturing information such as the management number of the cast pipe, in the limited space on the axial end face at the receiving end of the cast pipe, and that allows the information to be read without misinterpretation.

[0007] The object of the present invention is to provide a method for manufacturing a cast pipe that allows a large amount of information, including manufacturing information of the cast pipe, to be displayed on the axial end face of the receiving end of the cast pipe, even in a limited space, and that allows the information to be read without misinterpretation. [Means for solving the problem]

[0008] A method for manufacturing a cast pipe according to one embodiment of the present invention is a method for manufacturing a cast pipe having a flange-shaped socket end on one axial end. The method for manufacturing the cast pipe comprises a pipe casting step of forming a cast pipe having the socket end by casting, and an engraving step of engraving a two-dimensional code containing at least manufacturing information of the cast pipe onto the axial end face of the socket end using laser light emitted from a laser light emission device (first method).

[0009] According to the method described above, a two-dimensional code containing at least manufacturing information of the cast pipe can be directly engraved onto the axial end face of the cast socket end using a laser beam. This allows the two-dimensional code to display a lot of information, including manufacturing information such as the management number of the cast pipe, even if the space on the axial end face of the socket end is limited.

[0010] Furthermore, since the laser beam engraves the two-dimensional code by scraping or charring the axial end surface of the socket end, the cells of the two-dimensional code can be clearly displayed even if the axial end surface of the socket end of the cast tube is rough.

[0011] In addition, the two-dimensional code engraved as described above can display normal information even if minute defects occur in the cell due to the roughness of the axial end face of the receiving end, while it will not display incorrect information if a large defect occurs in the cell that makes it unreadable.

[0012] Therefore, it is possible to provide a method for manufacturing a cast pipe that allows a large amount of information, including manufacturing information of the cast pipe, to be displayed on the axial end face of the receiving end of the cast pipe, even in a limited space, and that allows the information to be read without misinterpretation.

[0013] In the first method described above, the method for manufacturing a cast tube further comprises: an identification step of acquiring an image of the two-dimensional code engraved in the engraving step and identifying whether the two-dimensional code is in an information displayable state or an information displayable state; and, if the identification step identifies the two-dimensional code as being in an information displayable state, a re-engraving step of engraving a new two-dimensional code, a second code, containing the same information as the first code, which is the two-dimensional code engraved in the engraving step, onto the axial end face of the socket end using the laser beam (second method).

[0014] As a result, if the first code, which is a two-dimensional code engraved during the engraving process, is in an information-display-unable state and cannot display information including manufacturing information, a new second code, which contains the same information as the first code, can be re-engraved. Therefore, the information can be displayed more reliably using the second code.

[0015] In the second method described above, in the re-engraving step, the second code is engraved by the laser beam at a position different in the circumferential direction from the position where the first code was engraved on the axial end face of the socket end (third method).

[0016] This allows the second code to be engraved while avoiding areas that cause defects in the engraved two-dimensional code, such as relatively large depressions formed on the axial end face of the socket end of a cast pipe. Therefore, it is possible to engrave a more reliably readable two-dimensional code by preventing the second code from having the same defects as the first code.

[0017] In the second method described above, in the re-engraving step, the first code is scraped off from the axial end face of the socket end with the laser beam, and then, with the axial end face of the socket end viewed in the axial direction, the second code is engraved with the laser beam at a position where at least a portion of the second code overlaps with the position where the first code was engraved on the axial end face of the socket end (fourth method).

[0018] This allows the first code to be scraped away, and the second code to be engraved at a position where at least a portion of the second code overlaps with the position where the first code was engraved. Therefore, the second code can be engraved using a limited space. Consequently, even in situations where there is less space to engrave a two-dimensional code on the axial end face of the socket end, a greater amount of information, including manufacturing information for the cast pipe, can be displayed more reliably.

[0019] In the first method described above, the method for manufacturing a cast tube further includes a relative position adjustment step of adjusting the relative position between the cast tube and the laser beam emission device such that the axial end face of the receiving end is included within the range to which the laser beam emission device can irradiate the laser beam (fifth method).

[0020] According to the method described above, the relative position between the cast tube and the laser beam emitter can be adjusted so that a two-dimensional code can be engraved on the axial end face of the socket end of the cast tube. Therefore, even when engraving the two-dimensional code on multiple types of tubes with different socket end diameters, for example, the two-dimensional code can be engraved more reliably on the axial end face of the socket end of the cast tube.

[0021] In the first method, in the pipe casting process, uneven symbols are formed on the axial end face of the socket end portion. The method for manufacturing the cast pipe further includes a reference symbol extraction step of extracting a reference symbol from the uneven symbols by an uneven symbol reading unit that reads the uneven symbols formed in the pipe casting process, and a printing position determination step of rotating the cast pipe based on the position of the reference symbol extracted in the reference symbol extraction step to determine a printing position for printing the two-dimensional code. In the printing step, the two-dimensional code is printed at the printing position (the sixth method).

[0022] In the above method, the two-dimensional code is printed at the printing position determined by rotating the cast pipe based on the position of the reference symbol extracted from the uneven symbols formed on the axial end face of the socket end portion of the cast pipe. Thereby, when looking at the axial end face of the socket end portion in the axial direction, the two-dimensional code can be more reliably printed at a position that does not overlap with the uneven symbols. Therefore, a method for manufacturing a cast pipe that can more reliably print the two-dimensional code in a space where the uneven symbols are not formed on the axial end face of the socket end portion of the cast pipe can be provided.

[0023] In the method according to any one of the first to sixth methods, in the printing step, before printing the two-dimensional code, a plane on which the two-dimensional code can be printed is formed on the axial end face of the socket end portion by laser light (the seventh method).

[0024] Thereby, the two-dimensional code can be printed on the plane formed on the axial end face of the socket end portion. Therefore, the two-dimensional code can be printed more clearly. Thus, more information including the manufacturing information of the cast pipe can be more reliably displayed.

[0025] A casting pipe marking device according to an embodiment of the present invention includes a two-dimensional code acquisition unit that acquires a two-dimensional code including at least manufacturing information of a casting pipe having a flange-shaped receiving end portion on one end side in the axial direction, a laser light emitting unit that performs surface processing of the casting pipe by irradiating the casting pipe with laser light, and an engraving control unit that controls the laser light emitting unit so as to engrave the two-dimensional code acquired by the two-dimensional code acquisition unit on an axial end surface of the receiving end portion by the laser light (first configuration).

[0026] According to the above configuration, a two-dimensional code including at least the manufacturing information of the casting pipe can be directly engraved on the axial end surface of the cast receiving end portion by laser light. Thereby, even if the space on the axial end surface of the receiving end portion is limited, a lot of information including manufacturing information such as the management number of the casting pipe can be displayed by the two-dimensional code.

[0027] Moreover, by engraving the two-dimensional code with laser light, the laser light scrapes or burns the axial end surface of the receiving end portion, so even if the axial end surface of the receiving end portion of the casting pipe is rough, the cells of the two-dimensional code can be clearly displayed.

[0028] In addition to this, the two-dimensional code engraved in this way can display normal information even if fine defects occur in the cells due to the roughness of the axial end surface of the receiving end portion, while it does not display incorrect information when large defects that make it impossible to read occur in the cells.

[0029] Therefore, it is possible to provide a casting pipe marking device that can display a lot of information including the manufacturing information of the casting pipe in a limited space on the axial end surface of the receiving end portion of the casting pipe and can engrave a two-dimensional code that can be read without misidentifying the information.

[0030] In the first configuration described above, the cast tube marking apparatus further includes a two-dimensional code image acquisition unit that acquires an image of the two-dimensional code marked by the laser beam emission unit, and a two-dimensional code identification unit that identifies whether the image of the two-dimensional code acquired by the two-dimensional code image acquisition unit is in an information displayable state or an information displayable state. The marking control unit controls the laser beam emission unit to mark a new two-dimensional code, a second code, containing the same information as the first code, which is the marked two-dimensional code, on the axial end face of the receiving end using the laser beam when the two-dimensional code identification unit identifies the two-dimensional code as being in the information displayable state (second configuration).

[0031] As a result, if the first two-dimensional code that is engraved is in an information-displaying state where it cannot display information including manufacturing information, a new second two-dimensional code containing the same information as the first code can be re-engraved. Therefore, the information can be displayed more reliably using the second code.

[0032] In the second configuration described above, the engraving control unit controls the laser beam emission unit to engrave the second code with the laser beam at a position different in the circumferential direction from the position where the first code was engraved on the axial end face of the receiving end (third configuration).

[0033] This allows the second code to be engraved while avoiding areas that cause defects in the engraved two-dimensional code, such as relatively large depressions formed on the axial end face of the socket end of a cast pipe. Therefore, it is possible to engrave a more reliably readable two-dimensional code by preventing the second code from having the same defects as the first code.

[0034] In the second configuration described above, the engraving control unit, after scraping the first code from the axial end face of the socket end with the laser light, controls the laser light emission unit to engrave the second code with the laser light at a position where at least a portion of the second code overlaps with the position where the first code was engraved on the axial end face of the socket end, when viewed in the axial direction (fourth configuration).

[0035] This allows the first code to be scraped away, and the second code to be engraved at a position where at least a portion of the second code overlaps with the position where the first code was engraved. Therefore, the second code can be engraved using a limited space. Consequently, even in situations where there is less space to engrave a two-dimensional code on the axial end face of the socket end, a greater amount of information, including manufacturing information for the cast pipe, can be displayed more reliably.

[0036] In the first configuration described above, the cast tube marking device further comprises: a rotation control unit for controlling the rotation of the cast tube; a relief symbol reading unit for reading relief symbols formed on the axial end face of the receiving end of the cast tube; a reference symbol extraction unit for extracting a reference symbol from the relief symbols read by the relief symbol reading unit; and a marking position determination unit for determining the marking position for marking the two-dimensional code based on the position of the reference symbol (fifth configuration).

[0037] In the above configuration, a two-dimensional code is engraved at an engraving position determined by rotating the cast pipe based on the position of a reference symbol extracted from the uneven symbols formed on the axial end face of the receiving end of the cast pipe. This makes it possible to more reliably engrave the two-dimensional code at a position that does not overlap with the uneven symbols when viewed in the axial direction on the axial end face of the receiving end of the cast pipe. Therefore, a cast pipe engraving device can be provided that can more reliably engrave the two-dimensional code in the space on the axial end face of the receiving end of the cast pipe where the uneven symbols are not formed. [Effects of the Invention]

[0038] A method for manufacturing a cast pipe according to one embodiment of the present invention comprises a pipe casting step of forming a cast pipe having a socket end by casting, and an engraving step of engraving a two-dimensional code containing at least manufacturing information of the cast pipe onto the axial end face of the socket end using laser light emitted from a laser light emission device.

[0039] A cast pipe marking apparatus according to one embodiment of the present invention includes: a two-dimensional code acquisition unit that acquires a two-dimensional code including at least manufacturing information of a cast pipe having a flange-shaped socket end on one axial end; a laser beam emission unit that performs surface processing of the cast pipe by irradiating the cast pipe with laser light; and a marking control unit that controls the laser beam emission unit so as to mark the axial end face of the socket end with the two-dimensional code acquired by the two-dimensional code acquisition unit.

[0040] As a result, even if the space on the axial end face of the socket end is limited, a lot of information, including manufacturing information such as the management number of the cast pipe, can be displayed on the axial end face of the socket end using a two-dimensional code. Moreover, by engraving the two-dimensional code with laser light, the cells of the two-dimensional code can be clearly displayed even if the axial end face of the socket end of the cast pipe is rough. In addition, the two-dimensional code will not display incorrect information if there is a large defect in the cells that makes it unreadable. Therefore, a lot of information, including the manufacturing information of the cast pipe, can be displayed on the axial end face of the socket end of the cast pipe even in a limited space, and the information can be read without misinterpretation. [Brief explanation of the drawing]

[0041] [Figure 1] Figure 1 shows a schematic configuration of a cast tube marking device. [Figure 2] Figure 2 is a view of the cast tube marking device described in Figure 1, viewed in the axial direction. [Figure 3] Figure 3 is a flowchart showing the method for manufacturing cast pipes. [Figure 4]Figure 4 shows a schematic configuration of a cast tube marking device according to Embodiment 2. [Figure 5] Figure 5 is a view of the casting tube marking device described in Figure 4, viewed in the axial direction. [Figure 6] Figure 6 is a flowchart showing the method for manufacturing a cast pipe according to Embodiment 2. [Figure 7] Figure 7 shows a schematic configuration of a cast tube marking device according to a modified example of Embodiment 2. [Figure 8] Figure 8 is a view of the casting tube marking device described in Figure 7, viewed in the axial direction. [Figure 9] Figure 9 is a flowchart showing a method for manufacturing a cast pipe according to a modified example of Embodiment 2. [Figure 10] Figure 10 shows a schematic configuration of a cast tube marking device according to Embodiment 3. [Figure 11] Figure 11 is a view of the cast tube marking device described in Figure 10, viewed in the axial direction. [Figure 12] Figure 12 is a flowchart showing the method for manufacturing a cast pipe according to Embodiment 3. [Figure 13] Figure 13 shows a schematic configuration of a cast tube marking device according to another embodiment. [Figure 14] Figure 14 shows a plane formed on the end face of the receiving end of a cast pipe according to another embodiment. [Modes for carrying out the invention]

[0042] The following describes each embodiment with reference to the drawings. In each drawing, the same parts are denoted by the same reference numerals, and the description of those parts will not be repeated. Note that the dimensions of the components in each drawing do not faithfully represent the dimensions of the actual components or the dimensional ratios of each component.

[0043] In the following explanation, the axial direction refers to the direction in which the axis P of the pipe 99 extends. The radial direction refers to the direction perpendicular to the axis P of the pipe 99. The circumferential direction refers to the direction in which the outer surface of the pipe 99 extends, when viewed in the axial direction.

[0044] Furthermore, in the following explanation, the expressions "fix," "connect," and "attach" (hereinafter referred to as "fixing, etc.") include not only cases where components are directly fixed to each other, but also cases where they are fixed to each other via other components. In other words, in the following explanation, the expressions "fixing, etc." include both direct and indirect fixing of components to each other.

[0045] [Embodiment 1] Figure 1 is a diagram showing a schematic configuration of a cast pipe marking device 1 according to an embodiment of the present invention. Figure 2 is a view of the cast pipe marking device 1 shown in Figure 1 in the axial direction. As shown in Figure 2, the cast pipe marking device 1 is a device for marking a two-dimensional code X containing manufacturing information of the pipe 99 on the axial end face 90a of the receiving end 90 of the pipe 99.

[0046] As shown in Figures 1 and 2, the pipe 99 is, for example, a cast iron pipe used for water supply. The pipe 99 has a flange-shaped socket end 90 on one axial end. The pipe 99 may be a cast pipe other than a cast iron pipe.

[0047] The axial end face 90a of the socket end 90 is formed in an annular shape with a predetermined width in the radial direction. The end face 90a of the socket end 90 has small depressions (not shown) on its surface that occur due to the casting conditions.

[0048] The socket end 90 has a two-dimensional code X on its end face 90a containing manufacturing information for the pipe 99. Specifically, the two-dimensional code X is engraved on the end face 90a of the socket end 90 by the laser light L of the laser light emission unit 6, which will be described later. The two-dimensional code X is located at a predetermined position 90b in the circumferential direction on the end face 90a of the socket end 90, in a position that does not protrude radially. Note that the pipe 99 corresponds to the cast pipe, and the end face 90a corresponds to the axial end face.

[0049] (QR code) The two-dimensional code X is formed at a predetermined position 90b on the end face 90a of the receiving end 90 by surface processing with laser light L from the laser light emission unit 6, which will be described later. Specifically, the two-dimensional code X is composed of multiple rectangular cells Xa, Xb which are formed in a matrix-like manner by the laser light L from the laser light emission unit 6. The two-dimensional code X is, for example, a QR code (registered trademark). The two-dimensional code may also be, for example, DataMatrix, Aztec code, PDF417, or MaxiCode. Multiple types of two-dimensional codes may be included.

[0050] The two-dimensional code X is configured to display a large amount of information, including manufacturing information such as the management number of the pipe 99. This allows the two-dimensional code X to display a large amount of the aforementioned information even if the space on the end face 90a of the receiving end 90 of the pipe 99 is limited. The two-dimensional code X is configured so that the information can be read by a known reading device.

[0051] The aforementioned information, including manufacturing information, includes, for example, the type of pipe 99, nominal diameter, manufacturing plant, year of manufacture, lot number, manufacturer, and individual pipe identification number. This information may also include other information related to the manufacturing of pipe 99. Furthermore, this information may include information other than the manufacturing information of pipe 99.

[0052] Specifically, the two-dimensional code X has multiple rectangular first cells Xa and multiple rectangular second cells Xb.

[0053] The first cell Xa has lost its surface smoothness due to processing by the laser light L from the laser light emission unit 6, which will be described later. In other words, the surface of the first cell Xa is rough. Therefore, the first cell Xa has lost its luster due to the diffuse reflection of light. On the other hand, the surface of the second cell Xb has been scorched by processing by the laser light L from the laser light emission unit 6. Therefore, the second cell Xb is darker than the first cell Xa.

[0054] In this way, the two-dimensional code X, composed of the first cell Xa and the second cell Xb, is formed by being scraped or charred by processing with the laser beam L from the laser beam emission unit 6. As a result, even if the surface of the end face 90a of the receiving end 90 is rough, the two-dimensional code X can be clearly formed by scraping or charring the surface of the end face 90a with the laser beam L.

[0055] (Casting tube marking device) As shown in Figure 1, the cast tube marking device 1 includes a rotary drive unit 5, a laser beam emission unit 6 (laser beam emission device), and a control unit 9.

[0056] As shown in Figures 1 and 2, the rotary drive unit 5 includes a plurality of roller sections 5a that rotatably support the pipe 99 from below. The rotary drive unit 5 rotates the pipe 99 around the axis P by rotating the plurality of roller sections 5a. The rotary drive unit may also rotate the pipe around the axis using known configurations other than the roller sections.

[0057] (Laser light emission section) The laser beam emission unit 6 is a device that performs surface processing on the tube 99 by emitting laser light L from the emission port 6a and irradiating the tube 99 with it. The laser beam emission unit 6 is configured to emit known laser light L capable of processing the surface of the tube 99. The laser light L is, for example, a YAG laser, a CO2 laser, a semiconductor laser, etc. The laser light L may be any laser other than a YAG laser, CO2 laser, or semiconductor laser, as long as it is capable of processing the surface of the tube 99.

[0058] The laser beam emission unit 6 has an output capable of surface processing the end face 90a of the socket end 90 using the laser beam L. Specifically, the laser beam emission unit 6 is configured to scrape or char the surface of the end face 90a of the socket end 90 using the laser beam L. The laser beam emission unit 6 can adopt any known configuration as long as it can scrape or char the surface of the end face 90a of the socket end 90.

[0059] As shown in Figure 2, the laser beam emission unit 6, based on the marking control signal described later, marks the end face 90a of the receiving end 90 with a two-dimensional code X using the laser beam L.

[0060] (Control Unit) As shown in Figure 1, the control unit 9 controls the driving of the rotation drive unit 5 and the laser beam emission unit 6. Specifically, the control unit 9 includes a rotation control unit 11, a two-dimensional code acquisition unit 21, and an engraving control unit 31.

[0061] As shown in Figures 1 and 2, the rotation control unit 11 rotates the pipe 99 by controlling the rotation drive unit 5 based on the marking control signal output from the marking control unit 31, which will be described later. Specifically, the rotation control unit 11 rotates the pipe 99 by rotating a plurality of roller units 5a.

[0062] The two-dimensional code acquisition unit 21 acquires the two-dimensional code X from a storage unit (not shown) or the like. The storage unit stores the two-dimensional code X, which includes manufacturing information such as the management number of the tube 99. The storage unit may be located in the control unit or in a component other than the control unit. The two-dimensional code acquisition unit may also acquire the two-dimensional code X from a source other than the storage unit. For example, the two-dimensional code acquisition unit may acquire the two-dimensional code X from a two-dimensional code generation unit (not shown) that generates the two-dimensional code X.

[0063] The engraving control unit 31 generates an engraving control signal for engraving the two-dimensional code X acquired by the two-dimensional code acquisition unit 21 onto a predetermined position 90b on the end face 90a of the receiving end 90 using a laser beam L. The engraving control signal is output to the rotation control unit 11 and also to the laser beam emission unit 6.

[0064] The marking control signal causes the rotation control unit 11 to rotate the tube 99 so that a predetermined position 90b for marking the two-dimensional code X on the end face 90a of the receiving end 90 is positioned opposite the outlet 6a of the laser beam emission unit 6. As a result, the rotation control unit 11, upon receiving the marking control signal from the marking control unit 31, rotates the tube 99 so that the predetermined position 90b faces the outlet 6a of the laser beam emission unit 6.

[0065] The marking control signal causes the laser beam emitter 6 to emit laser light L and mark the two-dimensional code X at the predetermined position 90b. As a result, the laser beam emitter 6, which has received the marking control signal from the marking control unit 31, marks the two-dimensional code X at the predetermined position 90b using the laser light L.

[0066] The cast pipe marking apparatus 1 according to the embodiment described above includes a two-dimensional code acquisition unit 21 that acquires a two-dimensional code X containing at least manufacturing information of a pipe 99 having a flange-shaped socket end 90 on one axial end; a laser beam emission unit 6 that performs surface processing of the pipe 99 by irradiating the pipe 99 with laser light L; and a marking control unit 31 that controls the laser beam emission unit 6 so as to mark the two-dimensional code X acquired by the two-dimensional code acquisition unit 21 onto the axial end face 90a of the socket end 90 with the laser light L.

[0067] According to the above configuration, a two-dimensional code X containing at least the manufacturing information of the pipe 99 can be directly engraved on the axial end face 90a of the cast socket end 90 using a laser beam L. This allows the two-dimensional code X to display a lot of information, including manufacturing information such as the management number of the pipe 99, even if the space on the axial end face 90a of the socket end 90 is limited.

[0068] Furthermore, by imprinting the two-dimensional code X with a laser beam L, the laser beam L scrapes or chars the axial end face 90a of the receiving end 90, so even if the surface of the axial end face 90a of the receiving end 90 of the pipe 99 is rough, the cells Xa and Xb of the two-dimensional code X can be clearly displayed.

[0069] In addition, the two-dimensional code X engraved in this manner can display normal information even if minute defects occur in cells Xa and Xb due to the roughness of the axial end face 90a of the receiving end 90, while it will not display incorrect information if large defects that make the cells unreadable occur.

[0070] Therefore, it is possible to provide a cast pipe marking device 1 that can engrave a two-dimensional code on the axial end face 90a of the receiving end 90 of the pipe 99, which can display a large amount of information, including manufacturing information of the pipe 99, even in a limited space, and which can be read without misinterpreting the information.

[0071] (Method for manufacturing cast pipes with two-dimensional codes) Next, with reference to Figures 1 to 3, a method for manufacturing a tube 99 in which a two-dimensional code X is engraved on the end face 90a of the receiving end 90 by laser light L will be described. Figure 3 is a flowchart showing the method for manufacturing the tube 99.

[0072] When the flow shown in Figure 3 starts (START), step SA1 casts a pipe 99 having a flange-shaped socket end 90.

[0073] Next, in step SA2, as shown in Figures 1 and 2, the pipe 99 is placed on the roller section 5a of the rotary drive unit 5. Subsequently, the laser beam emission unit 6 is positioned so that its output port 6a faces the end face 90a of the receiving end 90 of the pipe 99. Then, the rotation control unit 11 of the control unit 9 rotates the roller section 5a to rotate the pipe 99 so that the output port 6a of the laser beam emission unit 6 faces a predetermined position 90b on the end face 90a of the receiving end 90 where the two-dimensional code X is engraved.

[0074] Next, in step SA3 of the flowchart shown in Figure 3, as shown in Figure 2, the laser beam emitter 6 irradiates a predetermined position 90b on the end face 90a of the receiving end 90 with laser light L to engrave the two-dimensional code X. After that, the flowchart shown in Figure 3 is completed (END).

[0075] Step SA1 corresponds to the pipe casting process, and Step SA3 corresponds to the marking process.

[0076] The method for manufacturing the pipe 99 according to the embodiment described above is a method for manufacturing a pipe 99 having a flange-shaped socket end 90 on one end in the axial direction. The method for manufacturing the pipe 99 includes a pipe casting step SA1 in which a pipe 99 having a socket end 90 is formed by casting, and an engraving step SA3 in which a two-dimensional code X containing at least manufacturing information of the pipe 99 is engraved on the axial end face 90a of the socket end 90 with laser light L emitted from a laser light emission device 6.

[0077] According to the method described above, a two-dimensional code X containing at least the manufacturing information of the pipe 99 can be directly engraved on the axial end face 90a of the cast socket end 90 using a laser beam L. This allows the two-dimensional code X to display a lot of information, including manufacturing information such as the management number of the pipe 99, even if the space on the axial end face 90a of the socket end 90 is limited.

[0078] Furthermore, since the laser beam L engraves the two-dimensional code X by scraping or charring the axial end surface 90a of the socket end 90, cells Xa and Xb of the two-dimensional code X can be clearly displayed even if the axial end surface 90a of the socket end 90 of the pipe 99 is rough.

[0079] In addition, as described above, the engraved two-dimensional code X can display normal information even if minute defects occur in cells Xa and Xb due to the roughness of the axial end face 90a of the receiving end 90, while it will not display incorrect information if large defects that make the cells unreadable occur.

[0080] Therefore, it is possible to provide a method for manufacturing a pipe 99 that allows a large amount of information, including manufacturing information of the pipe 99, to be displayed on the axial end face 90a of the receiving end 90 of the pipe 99 even in a limited space, and that allows the information to be read without misinterpretation.

[0081] [Embodiment 2] Figure 4 is a diagram showing the schematic configuration of the cast tube marking device 200 according to Embodiment 2. Figure 5 is a view of the cast tube marking device 200 described in Figure 4 in the axial direction.

[0082] As shown in Figures 4 and 5, the cast pipe marking device 200 according to Embodiment 2 acquires an image of the first two-dimensional code (first code) 200X1 engraved on the pipe 299 and identifies whether or not information can be displayed. In addition, if the cast pipe marking device 200 identifies that the first code 200X1 cannot display information, it engraves a new two-dimensional code (second code) 200X2 capable of displaying the same information as the first code 200X1 on the end face 90a of the receiving end 90 at a position circumferentially different from the position where the first code 200X1 was engraved. In this way, the cast pipe marking device 200 repeats the operation of engraving (re-engraving) a new nth code capable of displaying the same information as the first code 200X1 on the end face 90a of the receiving end 90 at a position circumferentially different from the position where the previous two-dimensional code ((n-1) code) was engraved, until the nth two-dimensional code (nth code) is identified as being capable of displaying information.

[0083] In the above respects, the cast tube marking device 200 differs from the cast tube marking device 1 of Embodiment 1. In the following, components similar to those in Embodiment 1 are denoted by the same reference numerals and their descriptions are omitted, and only components different from Embodiment 1 are described. In addition, in the following description, for the sake of simplicity, the case in which the second code 200X2 is identified as being capable of displaying information will be described.

[0084] As shown in Figure 5, the receiving end 90 of the pipe 299 has a first code 200X1 and a second code 200X2 on its end face 90a.

[0085] The first code 200X1 is a two-dimensional code whose image has been acquired by the two-dimensional code image acquisition unit 207 (described later) and which has been identified as being in an information display-unavailable state by the two-dimensional code identification unit 241 (described later). The first code 200X1 has a defect K in at least a part of cells Xa and Xb, for example, a depression formed by casting. The defect K is of a size that is identified as being in an information display-unavailable state by the two-dimensional code identification unit 241 (described later). The defect K is, for example, one or more of the first cell Xa or the second cell Xb are missing. The defect K may be a defect other than a depression, for example, a casting defect caused by slag generated during casting, a mechanical defect such as a scratch, or a defect due to corrosion or wear.

[0086] The second code 200X2 is a two-dimensional code whose image has been acquired by the two-dimensional code image acquisition unit 207 (described later) and which has been identified as being in a state where information can be displayed by the two-dimensional code identification unit 241 (described later). The second code 200X2 is located at a different position in the circumferential direction from the position where the first code 200X1 is engraved on the end face 90a of the receiving end 90. As a result, it is highly likely that the second code 200X2 does not have the same defect K as the first code 200X1.

[0087] As shown in Figures 4 and 5, the cast tube marking device 200 includes a rotary drive unit 5, a laser beam emission unit 6, a two-dimensional code image acquisition unit 207, and a control unit 209.

[0088] The control unit 209 includes a rotation control unit 11, a two-dimensional code acquisition unit 21, an engraving control unit 231, and a two-dimensional code identification unit 241.

[0089] The two-dimensional code image acquisition unit 207 has the function of acquiring an image of a two-dimensional code, and a known two-dimensional code image acquisition device can be used. The two-dimensional code image acquisition unit 207 has a reading unit (not shown). The two-dimensional code image acquisition unit 207 is installed such that the reading unit faces the end face 90a of the receiving end 90.

[0090] The two-dimensional code image acquisition unit 207 acquires images of the two-dimensional codes 200X1 and 200X2 engraved on the end face 90a of the receiving end 90 by the laser beam emission unit 6, and outputs the acquired image data to the two-dimensional code identification unit 241 of the control unit 209.

[0091] Similar to Embodiment 1, the engraving control unit 231 generates an engraving control signal for engraving the first two-dimensional code acquired by the two-dimensional code acquisition unit 21 as the first code 200X1 at a predetermined position 90b on the end face 90a of the receiving end 90 using laser light L. The engraving control signal is output to the rotation control unit 11 and also to the laser light emission unit 6.

[0092] The marking control signal causes the rotation control unit 11 to rotate the tube 299 so that a predetermined position 90b on the end face 90a of the receiving end 90 is positioned opposite the output port 6a of the laser beam output unit 6. The marking control signal also causes the laser beam output unit 6 to emit laser light L to mark the first code 200X1 at the predetermined position 90b. As a result, the laser beam output unit 6, which has received the marking control signal from the marking control unit 231, marks the first code 200X1 at the predetermined position 90b using laser light L.

[0093] The two-dimensional code identification unit 241 receives a signal from the two-dimensional code image acquisition unit 207 that has acquired an image of the first code 200X1, and identifies whether the first code 200X1 is in an information displayable state or an information displayable state. The two-dimensional code identification unit 241 can employ a known two-dimensional code identification device. An information displayable state is a state in which a lot of information, including manufacturing information, can be read from the image of the two-dimensional code X acquired by the two-dimensional code image acquisition unit 207 (displayable state). An information displayable state is a state in which a lot of information, including manufacturing information, cannot be read from the image of the two-dimensional code X acquired by the two-dimensional code image acquisition unit 207 due to a missing value K (undisplayable state).

[0094] When the two-dimensional code identification unit 241 identifies that the first code 200X1 is in a state where information cannot be displayed, it generates a signal indicating that the first code 200X1 is in a state where information cannot be displayed and outputs it to the marking control unit 231.

[0095] If the marking control unit 231 receives a signal indicating that the first code 200X1 cannot be displayed, it obtains a new two-dimensional code, the second code 200X2, containing the same information as the first code 200X1, from the two-dimensional code acquisition unit 21. The marking control unit 231 then generates a re-marking control signal to mark (re-mark) the second code 200X2 with the laser beam L at a position circumferentially different from the position where the first code 200X1 was marked on the end face 90a of the receiving end 90. The re-marking control signal is output to the rotation control unit 11 and also to the laser beam emission unit 6.

[0096] The re-engraving control signal causes the rotation control unit 11 to rotate the tube 299 in the circumferential direction so that the laser beam emission port 6a of the laser beam emission unit 6 faces the position where the first code 200X1 was engraved, at a position different in the circumferential direction from the position where the first code 200X1 was engraved. The re-engraving control signal also causes the laser beam emission unit 6 to emit laser light L to engrave (re-engrav) the second code 200X2 at a position different in the circumferential direction from the position where the first code 200X1 was engraved. As a result, the laser beam emission unit 6, having received the re-engraving control signal from the engraving control unit 231, engraves (re-engraves) the second code 200X2 with laser light L at a position different in the circumferential direction from the position where the first code 200X1 was engraved.

[0097] The cast tube marking apparatus 200 according to Embodiment 2 described above further includes a two-dimensional code image acquisition unit 207 that acquires images of the two-dimensional codes 200X1 and 200X2 marked by the laser beam emission unit 6, and a two-dimensional code identification unit 241 that identifies whether the images of the two-dimensional codes 200X1 and 200X2 acquired by the two-dimensional code image acquisition unit 207 are in an information displayable state or an information displayable state. The marking control unit 231 controls the laser beam emission unit 6 to mark the axial end face 90a of the receiving end 90 with laser beam, a new two-dimensional code, the second code 200X2, which contains the same information as the first code 200X1, which is the marked two-dimensional code, when the two-dimensional code identification unit 241 identifies that the two-dimensional code 200X1 is in an information displayable state.

[0098] This allows for the re-engraving of a new two-dimensional code, the second code 200X2, which contains the same information as the first code 200X1, if the engraved first code 200X1 is in an information display failure state where it cannot display information including manufacturing information. Therefore, information can be displayed more reliably by using the second code 200X2.

[0099] In Embodiment 2, the engraving control unit 231 controls the laser beam emission unit 6 to engrave the second code 200X2 with the laser beam L at a position different in the circumferential direction from the position where the first code 200X1 was engraved on the axial end face 90a of the receiving end 90.

[0100] This allows the second code 200X2 to be engraved while avoiding parts that cause defects K in the engraved two-dimensional code, such as a relatively large recess formed on the axial end face 90a of the receiving end 90 of the pipe 299. Therefore, it is possible to prevent the same defects K as in the first code 200X1 from occurring in the second code 200X2, and to engrave a more reliably readable two-dimensional code X.

[0101] (Method for manufacturing cast pipes according to Embodiment 2) Next, with reference to Figures 4 to 6, a method for manufacturing a tube 299 in which two-dimensional codes 200X1 and 200X2 are engraved on the end face 90a of the receiving end 90 by laser light L will be described. Figure 6 is a flowchart showing the method for manufacturing the tube 299.

[0102] When the flow shown in Figure 6 starts (START), in step SA1, the pipe 299 is cast in the same manner as in Embodiment 1. Then, in step SA2, the laser beam emission unit 6 is set up in the same manner as in Embodiment 1, so that the outlet 6a of the laser beam emission unit 6 faces the end face 90a of the receiving end 90 of the pipe 299 which is placed on the roller portion 5a of the rotary drive unit 5. Subsequently, the pipe 299 is rotated so that the outlet 6a of the laser beam emission unit 6 faces a predetermined position 90b.

[0103] Next, in step SA3 of the flowchart shown in Figure 6, similar to Embodiment 1, as shown in Figure 5, the laser beam emitter 6 irradiates a predetermined position 90b with laser beam L to engrave a two-dimensional code. This two-dimensional code is the first two-dimensional code, the first code 200X1. The engraved first code 200X1 has a missing value K.

[0104] Next, in step SB4 of the flowchart shown in Figure 6, the two-dimensional code image acquisition unit 207 acquires the image of the first code 200X1, as shown in Figures 4 and 5.

[0105] Next, in step SB5 of the flowchart shown in Figure 6, the two-dimensional code identification unit 241 identifies whether the first code 200X1 is in an information displayable state or an information displayable state.

[0106] Next, in step SB6 of the flowchart shown in Figure 6, if the first code 200X1 is identified as being in an information display-unavailable state (as in step SB5 shown in Figure 6, where the result is NO), the second code 200X2 is engraved (re-engraved) on the end face 90a of the receiving end 90 at a position circumferentially different from the position where the first code 200X1 was engraved.

[0107] Then, returning to step SB4 of the flowchart shown in Figure 6, the two-dimensional code image acquisition unit 207 acquires an image of the second code 200X2. In the following step SB5, the two-dimensional code identification unit 241 identifies whether the second code 200X2 is in an information displayable state or an information displayable state.

[0108] In this way, the flow from step SB4 to SB6 is repeated until the nth code, which is the nth two-dimensional code whose image has been acquired by the two-dimensional code image acquisition unit 207, is identified by the two-dimensional code identification unit 241 as being in a state where information can be displayed.

[0109] In step SB5, if the two-dimensional code identification unit 241 identifies the read two-dimensional code as being in a state where information can be displayed (YES), the flow shown in Figure 6 is terminated (END).

[0110] Steps SB4 and SB5 correspond to the identification process, and step SB6 corresponds to the re-engraving process.

[0111] The method for manufacturing the pipe 299 according to Embodiment 2 described above further comprises: identification steps SB4 and SB5, which acquire an image of the two-dimensional code X engraved in the engraving step SA3 and identify whether the two-dimensional code X is in an information displayable state or an information displayable state; and a re-engraving step SB6, which, if the identification steps SB4 and SB5 identify that the two-dimensional code X is in an information displayable state, engraves a new two-dimensional code X, the second code 200X2, which contains the same information as the first code 200X1, which is the two-dimensional code X engraved in the engraving step SA3, onto the axial end face 90a of the receiving end 90 using a laser beam L.

[0112] As a result, if the first code 200X1, which is a two-dimensional code X engraved in the engraving process SA3, is in an information display failure state where it cannot display information including manufacturing information, a new two-dimensional code X, the second code 200X2, containing the same information as the first code 200X1, can be re-engraved. Therefore, information can be displayed more reliably by using the second code 200X2.

[0113] Furthermore, in the re-engraving step SB6 according to Embodiment 2, the second code 200X2 is engraved by laser light L at a position different in the circumferential direction from the position where the first code 200X1 was engraved on the axial end face 90a of the receiving end 90.

[0114] This allows the second code 200X2 to be engraved while avoiding parts that cause defects K in the engraved two-dimensional code X, such as a relatively large recess formed on the axial end face 90a of the receiving end 90 of the cast pipe 299. Therefore, it is possible to prevent the same defects K as in the first code 200X1 from occurring in the second code 200X2, and to engrave a more reliably readable two-dimensional code X.

[0115] [Modified version of Embodiment 2] Figure 7 shows a schematic configuration of a cast tube marking device 300 according to a modified example of Embodiment 2. Figure 8 is a view of the cast tube marking device 300 described in Figure 7 in the axial direction.

[0116] As shown in Figures 7 and 8, the cast tube marking device 300 according to a modified example of Embodiment 2 differs from the cast tube marking device 200 of Embodiment 2 in that, when it is identified that the engraved first code 300X1 is unable to display information, it scrapes off the first code 300X1 and then engraves (re-engraves) the second code 300X2 and subsequent n codes so that at least a portion of them overlaps the position where the first code 300X1 was engraved.

[0117] In the following, components similar to those in Embodiment 2 are denoted by the same reference numerals and their descriptions are omitted; only components different from Embodiment 2 will be described. Furthermore, for the sake of simplicity, the following description will focus on the case where the second code 300X2 is identified as being capable of displaying information.

[0118] As shown in Figure 8, the receiving end 90 of the tube 399 manufactured by the casting tube marking device 300 has a first code 300X1 and a second code 300X2 on its end face 90a.

[0119] The first code 300X1 is a two-dimensional code that has been identified as being in an information-displaying state by the two-dimensional code identification unit 241 and then erased by the laser beam emission unit 6. The first code 300X1 may be visually identifiable as long as it has been erased to the extent that it is identified as being in an information-displaying state by the two-dimensional code identification unit 241.

[0120] The second code 300X2 overlaps, at least partially, in the axial direction with respect to the position where the first code 300X1 is engraved on the end face 90a of the socket end 90. This allows a large amount of information, including manufacturing information for the pipe 399, to be displayed using the two-dimensional code, even if the space on the end face 90a of the socket end 90 is limited.

[0121] As shown in Figures 7 and 8, the cast tube marking device 300 includes a rotary drive unit 5, a laser beam emission unit 6, a two-dimensional code image acquisition unit 207, and a control unit 309.

[0122] The control unit 309 includes a rotation control unit 11, a two-dimensional code acquisition unit 21, an engraving control unit 331, and a two-dimensional code identification unit 241.

[0123] The marking control unit 331, similar to Embodiment 2, generates a marking control signal to mark the first code 300X1 at a predetermined position 90b on the end face 90a of the receiving end 90 using a laser beam L, and outputs the marking control signal to the rotation control unit 11 and the laser beam emission unit 6. As a result, the first code 300X1 is marked at the predetermined position 90b by the laser beam L.

[0124] When the engraving control unit 331 receives a signal indicating that the first code 300X1 is in an information display-unavailable state, it uses the laser beam L to scrape off the first code 300X1 from the end face 90a of the receiving end 90, and then generates a re-engraving control signal to engrave (re-engrav) the second code 300X2 so that at least a portion of it overlaps with the position where the first code 300X1 was engraved. The re-engraving control signal is output to the rotation control unit 11 and also to the laser beam emission unit 6.

[0125] The re-engraving control signal causes the rotation control unit 11 to rotate the tube 399 in the circumferential direction so that the output port 6a of the laser beam output unit 6 faces the position where the first code 300X1 was engraved. The re-engraving control signal causes the laser beam output unit 6 to emit laser beam L, thereby scraping off the first code 300X1 from the end face 90a of the receiving end 90.

[0126] The re-engraving control signal causes the laser beam emission unit 6 to engrave (re-engrav) the second code 300X2 such that at least a portion of the second code 300X2 overlaps axially with the position where the first code 300X1 was engraved.

[0127] The marking control unit 331 of the cast tube marking device 300 according to the modified embodiment 2 described above, after scraping the first code 300X1 from the axial end face 90a of the receiving end 90 with laser light, controls the laser beam emission unit 6 to mark the second code 300X2 with laser light at a position where at least a portion of the second code 300X2 overlaps with the position where the first code 300X1 was marked on the axial end face 90a of the receiving end 90, when viewed in the axial direction.

[0128] This allows the first code 300X1 to be scraped away, and the second code 300X2 to be engraved at a position where at least a portion of the first code 300X1 and the second code 300X2 overlap. Therefore, the second code 300X2 can be engraved using a limited space. Consequently, even in situations where there is less space to engrave the two-dimensional code 300X2 on the axial end face 90a of the receiving end 90, a greater amount of information, including the manufacturing information of the pipe 399, can be displayed more reliably.

[0129] (Method for manufacturing a cast pipe according to a modified example of Embodiment 2) Next, with reference to Figures 8 and 9, a method for manufacturing a tube 399 in which a two-dimensional code 300X2 is engraved on the end face 90a of the receiving end 90 by laser light L will be described. Figure 9 is a flowchart showing a method for manufacturing a tube 399 according to a modified example of Embodiment 2.

[0130] When the flow shown in Figure 9 starts (START), each step from step SA1 to SB5 is the same as in Embodiment 2.

[0131] In step SC6 of the flowchart shown in Figure 9, if the first code 300X1 is identified as being in an information display-less state (as in step SB5 shown in Figure 9, where the answer is NO), the first code 300X1 is scraped off from the end face 90a of the socket end 90 using the laser beam L. Subsequently, the second code 300X2 is engraved (re-engraved) on the end face 90a of the socket end 90 using the laser beam L at a position where at least a portion of the second code 300X2 overlaps with the position where the first code 300X1 was engraved.

[0132] Subsequently, similar to Embodiment 2, the process returns to step SB4 of the flowchart shown in Figure 9, and in the following step SB5, the flow of steps SB4 and SC6 is repeated until the nth two-dimensional code, the nth code, is identified as being in an information displayable state. If the acquired two-dimensional code is identified as being in an information displayable state in SB5 (YES), the flow shown in Figure 9 is terminated (END). Step SC6 corresponds to the re-engraving process.

[0133] In the re-engraving step SC6 of the manufacturing method for the tube 399 according to the modified embodiment 2 described above, the first code 300X1 is removed from the axial end face 90a of the socket end 90 by laser light L. Then, looking at the axial end face 90a of the socket end 90 in the axial direction, the second code 300X2 is engraved by laser light L at a position where at least a portion of the second code 300X2 overlaps with the position where the first code 300X1 was engraved on the axial end face 90a of the socket end 90.

[0134] This allows the first code 300X1 to be scraped away, and the second code 300X2 to be engraved at a position where at least a portion of the first code 300X1 and the second code 300X2 overlap. Therefore, the second code 300X2 can be engraved using a limited space. Consequently, even in situations where there is less space to engrave a two-dimensional code on the axial end face 90a of the receiving end 90, more information, including the manufacturing information of the pipe 399, can be displayed more reliably.

[0135] [Embodiment 3] Figure 10 is a diagram showing the schematic configuration of the cast tube marking device 400 according to Embodiment 3. Figure 11 is a view of the cast tube marking device 400 described in Figure 10 in the axial direction.

[0136] As shown in Figures 10 and 11, the cast pipe marking device 400 according to Embodiment 3 reads the embossed symbols S formed on the end face 90a of the receiving end 90 of the pipe 499 and extracts a reference symbol Sa from the embossed symbols S. In addition, it determines the marking position 490b for marking the two-dimensional code X on the end face 90a of the receiving end 90, based on the reference symbol Sa. In these respects, the cast pipe marking device 400 differs from the cast pipe marking device 1 of Embodiment 1. In the following, components similar to those in Embodiment 1 are denoted by the same reference numerals and their descriptions are omitted, and only components that differ from Embodiment 1 will be described.

[0137] As shown in Figure 11, the receiving end 90 of the pipe 499 has a raised symbol S on its end face 90a. The raised symbol S is formed by casting. The raised symbol S includes multiple letters and figures, and is formed on the end face 90a of the receiving end 90 so as to be arranged in the circumferential direction. The raised symbol S indicates, for example, the lot number of the pipe 499. The raised symbol may be formed by methods other than casting, and may indicate information other than the lot number.

[0138] The raised / recessed symbol S includes a reference symbol Sa. The reference symbol Sa is any character or figure among the characters and figures in the raised / recessed symbol S. As shown in Figure 11, the reference symbol Sa is, for example, a "water mark". The reference symbol Sa is extracted by the reference symbol extraction unit 451 of the control unit 409, which will be described later.

[0139] The two-dimensional code X is engraved at the engraving position 490b determined by the engraving position determination unit 461 of the control unit 409, which will be described later. The engraving position 490b is determined based on the position of the reference symbol Sa.

[0140] As shown in Figures 10 and 11, the cast tube marking device 400 includes a rotary drive unit 5, a laser beam emission unit 6, a relief symbol reading unit 407, and a control unit 409.

[0141] The control unit 409 includes a rotation control unit 11, a two-dimensional code acquisition unit 21, an engraving control unit 431, a reference symbol extraction unit 451, and an engraving position determination unit 461.

[0142] The unevenness symbol reading unit 407 has the function of reading unevenness symbols S, and a known unevenness symbol reading device can be used. The unevenness symbol reading unit 407 reads, for example, the unevenness symbols S formed on the end face 90a of the receiving end 90 of the pipe 499 that rotates around the axis P, and converts it into an image. The obtained image is then read by a known method.

[0143] The reference symbol extraction unit 451 extracts a reference symbol Sa from the raised and recessed symbols S read by the raised and recessed symbol reading unit 407. The reference symbol extraction unit 451 extracts as reference symbol Sa a symbol that has a high degree of shape agreement with the reference symbol registration data stored in a storage unit (not shown), for example. The reference symbol extraction unit 451 may use any other known method as long as it can extract the reference symbol Sa from the raised and recessed symbols S. As shown in Figure 11, in this embodiment, the reference symbol extraction unit 451 extracts the "water mark" as the reference symbol Sa. The reference symbol extraction unit may also extract a symbol other than the "water mark" as the reference symbol.

[0144] The marking position determination unit 461 determines the marking position 490b on the end face 90a of the receiving end 90, using the position of the reference symbol Sa as a reference. The marking position 490b is free from any irregularities that would hinder the marking of the raised symbol S and other two-dimensional codes X.

[0145] The engraving control unit 431 generates an engraving control signal to engrave the two-dimensional code X acquired by the two-dimensional code acquisition unit 21 at the engraving position 490b using the laser beam L. The engraving control signal is output to the rotation control unit 11 and also to the laser beam emission unit 6.

[0146] The marking control signal causes the rotation control unit 11 to rotate the tube 499 so that the marking position 490b is positioned opposite the output port 6a of the laser beam output unit 6.

[0147] The aforementioned marking control signal causes the laser beam emitter 6 to emit laser light L, thereby marking the two-dimensional code X at the marking position 490b.

[0148] The cast pipe marking device 400 according to Embodiment 3 described above further comprises: a rotation control unit 11 that controls the rotation of the pipe 499; a relief symbol reading unit 407 that reads relief symbols S formed on the axial end face 90a of the receiving end 90 of the pipe 499; a reference symbol extraction unit 451 that extracts a reference symbol Sa from the relief symbols S read by the relief symbol reading unit 407; and a marking position determination unit 461 that determines the marking position 490b for marking the two-dimensional code X based on the position of the reference symbol Sa.

[0149] In the above configuration, the two-dimensional code X is engraved at the marking position 490b, which is determined by rotating the pipe 499 based on the position of a reference symbol Sa extracted from the uneven symbols S formed on the axial end face 90a of the receiving end 90 of the pipe 499. This makes it possible to more reliably engrave the two-dimensional code X at a position that does not overlap with the uneven symbols S when viewed in the axial direction on the axial end face 90a of the receiving end 90. Thus, a cast pipe marking device 400 can be provided that can reliably engrave the two-dimensional code X in the space on the axial end face 90a of the receiving end 90 of the pipe 499 where the uneven symbols S are not formed.

[0150] (Method for manufacturing cast pipes according to Embodiment 3) Next, with reference to Figures 10 to 12, a method for manufacturing a pipe 499 in which a recessed symbol S is formed on the end face 90a of the receiving end 90 and a two-dimensional code X is engraved at the engraving position 490b will be described. Figure 12 is a flowchart showing the method for manufacturing a pipe 499 according to Embodiment 3.

[0151] When the flow shown in Figure 12 starts (START), in step SD1, a pipe is cast in which the recessed symbol S is formed on the end face 90a of the flange-shaped socket end 90.

[0152] Next, in step SD2, as shown in Figures 10 and 11, the unevenness symbol reading unit 407 reads the unevenness symbol S.

[0153] Next, in step SD3 of the flowchart shown in Figure 12, the reference symbol extraction unit 451 extracts the reference symbol Sa from the read relief symbols S.

[0154] Next, in step SD4, the marking position determination unit 461 determines the marking position 490b based on the reference symbol Sa.

[0155] Next, in step SD5, the rotation control unit 11, which receives the marking control signal from the marking control unit 431, rotates the tube 499 so that the output port 6a of the laser beam emitter 6 faces the marking position 490b.

[0156] Next, in step SD6, the laser beam emitter 6, which receives the marking control signal from the marking control unit 431, marks the two-dimensional code X at the marking position 490b. After that, the flow shown in Figure 12 is completed (END).

[0157] Step SD1 corresponds to the pipe casting process, steps SD2 and SD3 to the reference symbol extraction process, step SD4 to the marking position determination process, and steps SD5 and SD6 to the marking process.

[0158] In the pipe casting process SD1 of the pipe 499 manufacturing method according to Embodiment 3 described above, a raised and recessed symbol S is formed on the axial end face 90a of the receiving end 90. The pipe 499 manufacturing method further includes a reference symbol extraction process SD2, SD3 in which a reference symbol reading unit 407 reads the raised and recessed symbol S formed in the pipe casting process SD1 and extracts a reference symbol Sa from the raised and recessed symbols S, and an engraving position determination process SD4 in which the pipe 499 is rotated based on the position of the reference symbol Sa extracted in the reference symbol extraction processes SD2, SD3 to determine an engraving position 490b for engraving a two-dimensional code X. In the engraving processes SD5, SD6, the two-dimensional code X is engraved at the engraving position 490b.

[0159] In the method described above, the two-dimensional code X is engraved at the marking position 490b determined by rotating the pipe 499 based on the position of a reference symbol Sa extracted from the uneven symbols S formed on the axial end face 90a of the receiving end 90 of the pipe 499. This makes it possible to more reliably engrave the two-dimensional code X at a position that does not overlap with the uneven symbols S when viewed in the axial direction on the axial end face 90a of the receiving end 90. Thus, a method for manufacturing a pipe 499 is provided that allows for the reliable engraving of the two-dimensional code X in the space on the axial end face 90a of the receiving end 90 of the pipe 499 where the uneven symbols S are not formed.

[0160] (Other embodiments) Although embodiments of the present invention have been described above, the embodiments described above are merely examples for carrying out the present invention. Therefore, the invention is not limited to the embodiments described above, and it is possible to carry out the invention by appropriately modifying the embodiments described above without departing from the spirit of the invention.

[0161] In each of the above embodiments, the position of the laser beam emitter 6 relative to the pipes 99, 299, 399, and 499 is fixed. However, the cast pipe marking device may have a mechanism that allows the position of the laser beam emitter relative to the pipe to be adjusted. Specifically, the cast pipe marking device may have a mechanism that allows the relative position between the end face of the receiving end of the pipe and the output port of the laser beam emitter to be adjusted in at least one of the axial and radial directions.

[0162] Figure 13 shows a schematic configuration of a cast tube marking device 500 according to another embodiment. As shown in Figure 13, the cast tube marking device 500 has a relative position adjustment mechanism 508 that can adjust the laser beam emitter 6 in at least one of the axial and radial directions relative to the tube 99. More specifically, the cast tube marking device 500 has a rotary drive unit 5, a laser beam emitter 6, a relative position adjustment mechanism 508, and a control unit 509. The control unit 509 has a rotary control unit 11, a two-dimensional code acquisition unit 21, a marking control unit 31, and a relative position adjustment unit 571.

[0163] The relative position adjustment mechanism 508 adjusts the position of the laser beam emission port 6a of the laser beam emission device 6 relative to the end face 90a of the receiving end 90 in at least one of the axial and radial directions. Specifically, the relative position adjustment mechanism 508 adjusts the position of the laser beam emission device 6 relative to the pipe 99 in at least one of the axial and radial directions, for example, by combining a servo motor and an encoder. The relative position adjustment mechanism may be configured so that the rotational drive unit is movable in at least one of the axial and radial directions. Furthermore, the relative position adjustment mechanism may be implemented by other known techniques as long as it is possible to adjust the relative position between the end face of the receiving end and the laser beam emission port in at least one of the axial and radial directions.

[0164] The relative position adjustment unit 571 controls the drive of the relative position adjustment mechanism 508 to adjust the relative position between the pipe 99 and the laser beam emission device 6 so that the axial end face 90a of the receiving end 90 is included within the range in which the laser beam emission device 6 can irradiate the laser beam L.

[0165] The method for manufacturing such a tube 99 further includes a relative position adjustment step, which uses the relative position adjustment mechanism 508 and the relative position adjustment unit 571 of the casting tube marking device 500 to adjust the relative position between the tube 99 and the laser beam emission device 6 so that the axial end face 90a of the receiving end 90 is included within the range in which the laser beam emission device 6 can irradiate the laser beam L.

[0166] According to the method described above, the relative position between the pipe 99 and the laser beam emitter 6 can be adjusted so that the two-dimensional code X can be engraved on the axial end face 90a of the receiving end 90 of the pipe 99. Therefore, even when engraving the two-dimensional code X on multiple types of pipes with different diameters of the receiving end 90, for example, the two-dimensional code X can be more reliably engraved on the axial end face 90a of the receiving end 90 of the pipe 99.

[0167] In the above description, a relative position adjustment mechanism 508 that allows adjustment of the position of the laser beam emission device 6 relative to the end face 90a of the receiving end 90 of the pipe 99 in Embodiment 1 has been described. However, mechanisms for adjusting the position of the laser beam emission device may also be provided for the end faces of the receiving end 90 of pipes 299, 399, and 499 other than those in Embodiment 1.

[0168] Furthermore, the relative position adjustment step may be incorporated into the manufacturing process of the cast tube in each of the embodiments. In addition, the relative position adjustment step may be performed in the identification step of Embodiment 2 or a modified example of Embodiment 2, when the first code is identified as being in an information display-less state, to adjust the relative position between the cast tube and the laser beam emitter that emits laser light in at least one of the axial and radial directions based on the identification signal of the first code. In this case, in the re-engraving step, the second code is engraved on the axial end face of the receiving end of the cast tube by laser light at the relative position between the cast tube and the laser beam emitter adjusted in the relative position adjustment step.

[0169] According to the method described above, an image of the axial end face of the socket end is acquired after the engraving process. If the two-dimensional code is in a state where it cannot display information, the relative position between the cast tube and the laser beam emitter can be adjusted to a position where a normal two-dimensional code can be engraved on the axial end face of the socket end. Therefore, a normal two-dimensional code can be engraved more reliably on the axial end face of the socket end of the cast tube.

[0170] Figure 14 shows a plane 690c formed on the end face of the socket end of the cast pipe. In each of the above embodiments, the two-dimensional code X is engraved on the end face 90a of the socket end 90. However, the two-dimensional code may be engraved on a plane formed by a laser beam emitter before the two-dimensional code is engraved. The plane is smoother than the end face of the socket end where the plane is not formed.

[0171] In this case, in the engraving process for the cast pipe manufacturing method, before engraving the two-dimensional code, a plane on which the two-dimensional code can be engraved is formed on the axial end face of the socket end using laser light. This allows the two-dimensional code to be engraved on the plane formed on the axial end face of the socket end. Therefore, the two-dimensional code can be engraved more clearly. Thus, a lot of information, including the manufacturing information of the cast pipe, can be displayed more reliably.

[0172] The cast pipe marking devices 1,200, 300, 400, and 500 according to each of the above embodiments have different configurations from the cast pipe marking devices according to other embodiments. However, the cast pipe marking devices according to each embodiment may further have the configuration of the cast pipe marking device according to another embodiment. For example, the cast pipe marking device 200 according to Embodiment 2 may further have a recessed symbol reading unit 407, which is present in the cast pipe marking device 400 according to Embodiment 3, and a control unit 409 having a reference symbol extraction unit 451 and a marking position determination unit 461. In this case, the method for manufacturing a cast pipe according to each embodiment may further include steps according to the method for manufacturing a cast pipe according to another embodiment. [Industrial applicability]

[0173] The present invention can be used in a method for manufacturing a cast pipe having a flange-shaped socket end on one axial end, and in a cast pipe marking device. [Explanation of Symbols]

[0174] 1, 200, 300, 400, 500 Casting Tube Marking Device 5. Drive Rotating Part 5a Roller section 6. Laser beam emission section 207 Two-dimensional code image acquisition unit 407 Recessed symbol reading unit 508 Relative position adjustment mechanism 9, 209, 309, 409, 509 Control Unit 11 Rotation Control Unit 21 Two-dimensional code acquisition unit 31, 231, 331, 431 Engraving Control Unit 241 Two-dimensional code identification unit 451 Reference symbol extraction unit 461 Marking position determination section 571 Relative position adjustment unit 90 Socket end 90a end face 90b, 490b position, engraved position 690c plane 99, 299, 399, 499 tube X 2D code Xa, Cell 1 Xb Cell 2 200X1, 300X1 First Code 200X2, 300X2 Second Code K deficiency L Laser light S (concave / concave symbol) Sa (reference symbol)

Claims

1. A method for manufacturing a cast pipe having a flange-shaped socket end on one end in the axial direction, A pipe casting process in which a cast pipe having the aforementioned socket end is formed by casting, A marking step of marking the axial end face of the socket end with a two-dimensional code containing at least the manufacturing information of the cast pipe, using laser light emitted from a laser light emission device. Having, A method for manufacturing cast pipes.

2. In the method for manufacturing a cast pipe according to claim 1, An identification step involves acquiring an image of the two-dimensional code engraved in the engraving step and identifying whether the two-dimensional code is in an information displayable state or an information displayable state. If the identification step identifies that the two-dimensional code is in a state where the information cannot be displayed, a re-engraving step is performed in which a new two-dimensional code, a second code, containing the same information as the first code, which is the two-dimensional code engraved in the engraving step, is engraved on the axial end face of the receiving end using the laser beam. It further possesses, A method for manufacturing cast pipes.

3. In the method for manufacturing a cast pipe according to claim 2, In the re-engraving step, the second code is engraved by the laser beam at a position different in the circumferential direction from the position where the first code was engraved on the axial end face of the socket end. A method for manufacturing cast pipes.

4. In the method for manufacturing a cast pipe according to claim 2, In the re-engraving step, the first code is removed from the axial end face of the socket end by the laser beam, and then, with the axial end face of the socket end viewed in the axial direction, the second code is engraved by the laser beam at a position where at least a portion of the second code overlaps with the position where the first code was engraved on the axial end face of the socket end. A method for manufacturing cast pipes.

5. In the method for manufacturing a cast pipe according to claim 1, The invention further includes a relative position adjustment step of adjusting the relative position between the cast tube and the laser beam emission device such that the axial end face of the receiving end is included within the range in which the laser beam emission device can irradiate the laser beam. A method for manufacturing cast pipes.

6. In the method for manufacturing a cast pipe according to claim 1, In the pipe casting process, an uneven symbol is formed on the axial end surface of the receiving end. The method for manufacturing the cast pipe is as follows: A reference symbol extraction step involves extracting a reference symbol from the raised and recessed symbols formed in the pipe casting step using a raised and recessed symbol reading unit that reads the raised and recessed symbols. An engraving position determination step, in which the cast tube is rotated based on the position of the reference symbol extracted in the reference symbol extraction step to determine the engraving position for the two-dimensional code, It further possesses, In the marking step, the two-dimensional code is marked at the marking position. A method for manufacturing cast pipes.

7. In the method for manufacturing a cast pipe according to any one of claims 1 to 6, In the engraving process, before engraving the two-dimensional code, a plane on which the two-dimensional code can be engraved is formed on the axial end face of the receiving end using a laser beam. A method for manufacturing cast pipes.

8. A two-dimensional code acquisition unit that acquires a two-dimensional code containing at least manufacturing information of a cast pipe having a flange-shaped socket end on one end in the axial direction, A laser beam emission unit that performs surface processing on the cast tube by irradiating the cast tube with laser light, An engraving control unit controls the laser beam emission unit so as to engrave the two-dimensional code acquired by the two-dimensional code acquisition unit onto the axial end face of the receiving end using the laser beam, Having, Casting tube marking device.

9. In the cast tube marking apparatus according to claim 8, A two-dimensional code image acquisition unit acquires an image of the two-dimensional code engraved by the laser beam emission unit, A two-dimensional code identification unit identifies whether the image of the two-dimensional code acquired by the two-dimensional code image acquisition unit is in a state where information can be displayed or a state where information cannot be displayed. It further possesses, The marking control unit, When the two-dimensional code identification unit identifies that the two-dimensional code is in a state where information cannot be displayed, the laser beam emission unit is controlled to engrave a new two-dimensional code, a second code, containing the same information as the engraved first two-dimensional code, onto the axial end face of the receiving end using the laser beam. Casting tube marking device.

10. In the cast pipe marking apparatus according to claim 9, The marking control unit controls the laser beam emission unit to mark a second code with the laser beam at a position different in the circumferential direction from the position where the first code was marked on the axial end face of the receiving end. Casting tube marking device.

11. In the cast pipe marking apparatus according to claim 9, The marking control unit, after removing the first code from the axial end face of the socket end with the laser beam, controls the laser beam emission unit to mark the second code with the laser beam at a position where at least a portion of the second code overlaps with the position where the first code was marked on the axial end face of the socket end, when viewed in the axial direction. Casting tube marking device.

12. In the cast tube marking apparatus according to claim 8, A rotation control unit for controlling the rotation of the cast pipe, A bump symbol reading unit reads bump symbols formed on the axial end surface of the receiving end of the cast pipe, A reference symbol extraction unit extracts a reference symbol from the reference symbols read by the aforementioned reference symbol reading unit, An engraving position determination unit that determines the engraving position for the two-dimensional code based on the position of the aforementioned reference symbol, It further possesses, Casting tube marking device.

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