Automatic welding method

Abstract

An automatic welding method is disclosed. The disclosed automatic welding method comprises steps in which: (S110) a pipe having a first weld groove is transported to be loaded at a fit-up location in a welding area; (S120) a handling robot transports a hollow connection member having a second weld groove to the vicinity of the fit-up location in the welding area; (S130) a fit-up sensor measures the alignment state of the hollow connection member with respect to the fit-up location in the welding area, and the handling robot moves the location of the hollow connection member according to the result so as to align the weld grooves of the hollow connection member and the pipe; (S140) a welding robot performs tack welding on the aligned weld grooves; (S150) the welding robot performs root welding on the tack-welded weld grooves; and (S160) the welding robot performs filling-and-cap welding on the root-welded weld grooves.

Description

Automatic welding method

[0001] An automatic welding method is disclosed. More specifically, an automatic welding method capable of automatically welding a pipe and a hollow connecting member is disclosed.

[0002] Chemical plants, industrial plants, and buildings contain complex piping systems.

[0003] To install pipe systems in chemical, industrial, or building structures, multiple pipe spools that will form the pipe system are first fabricated at a pipe spool fabrication facility. These fabricated pipe spools are then transported to the chemical, industrial, or building site, where they are connected.

[0004] In this way, a plurality of pipe spools connected to each other are installed using supports or the like on steel or civil structures forming chemical plants, industrial plants, or buildings, and the plurality of pipe spools connected to each other are finally connected to stationary equipment such as columns, vessels, tanks, or heat exchangers, or to rotating equipment such as compressors or pumps, so that the entire pipe installation is constructed in chemical plants, industrial plants, or buildings.

[0005] Meanwhile, pipe spools, which form the piping systems of chemical plants, industrial plants, and buildings, vary in shape and size. For this reason, pipe spools are typically a high-mix, low-volume product, making manufacturing automation difficult. Consequently, automation was previously limited to certain manufacturing processes for simple pipe spools. Complex pipe spools were still manufactured manually at individual workshops, involving cutting, machining, moving, and welding pipes and fittings.

[0006] In addition, many tasks, including drawing management, material management, and inspection work essential for pipe spool production, were still handled based on bibliography, requiring personnel to take charge of each production process.

[0007] In addition, welding must be performed to connect pipes or to join hollow connecting parts such as pipes and fittings. However, in the past, welding work was performed manually or semi-automatically, which not only required a lot of time and manpower for welding work, but also resulted in the problem of welding defects.

[0008] One embodiment of the present invention provides an automatic welding method capable of automatically welding a pipe and a connecting member.

[0009] One aspect of the present invention is:

[0010] A step (S110) of transporting a pipe having a first welding groove formed thereon and placing it in a fit-up position of a welding site;

[0011] A step (S120) in which a handling robot transports a hollow connecting member having a second welding groove formed therein to the vicinity of a fit-up position of the welding site;

[0012] A step (S130) in which a fit-up sensor measures the alignment status of the hollow connecting member with respect to the fit-up position of the welding machine, and based on the result, the handling robot moves the position of the hollow connecting member to align the pipe and the hollow connecting member with respect to the welding grooves;

[0013] A step (S140) in which a welding robot performs tangible welding on the aligned welding grooves;

[0014] A step (S150) in which the welding robot performs root welding on the weld grooves that have been welded; and

[0015] An automatic welding method is provided, including a step (S160) in which a welding robot performs peeling and cap welding on the root-welded welding grooves.

[0016] In the above step (S110), the first groove of the pipe and in the above step (S120), the second groove of the hollow connecting member can be configured to be suitable for V-groove welding.

[0017] The above step (S140) can be performed in an all-position welding manner in a state where each of the pipes is fixed to the fit-up position of the welding site and the hollow connecting member is gripped by the handling robot.

[0018] The above steps (S150) and (S160) can be performed in a downward-looking welding manner, with the pipe and the hollow connecting member each being tangibly welded and the grip by the handling robot being released.

[0019] The above handling robot includes a gripper, and the gripper can be configured to grip the hollow connecting member while being inserted into the hollow portion of the hollow connecting member.

[0020] The gripper may include a main body extending in one direction and three or more stepped jaws movably coupled to one surface of the main body but spaced apart from each other at equal intervals and extending radially in a direction perpendicular to the direction in which the main body extends.

[0021] The above welding robot may include a laser vision sensor.

[0022] The above automatic welding method may further include a step (S135-1) of measuring a gap and a height difference between the first groove of the pipe and the second groove of the hollow connecting member using the laser vision sensor between the steps (S130) and (S140), and having the handling robot receive the gap and the height difference from the laser vision sensor, moving the hollow connecting member so that the gap and the height difference are adjusted to an allowable gap range and a allowable height difference range, respectively, thereby finely aligning the welding grooves of the pipe and the hollow connecting member.

[0023] In the above step (S135-1), the gap and height difference between the first groove of the pipe and the second groove of the hollow connecting member may be calculated by obtaining three or more gaps and three or more height differences from 3D coordinates on the lower surface of the first groove measured at three or more different points on the circumference of the first groove of the pipe, and 3D coordinates corresponding to each of these, and then averaging each of these.

[0024] The automatic welding method may further include, between the steps (S135-1) and (S140), a step (S135-2) of generating 3D coordinates on the lower surface of the first groove of the pipe along the circumference of the first groove using the laser vision sensor, and also generating 3D coordinates on the lower surface of the second groove of the hollow connecting member along the circumference of the second groove, and setting a welding path using the generated 3D coordinates.

[0025] The above automatic welding method may further include a step (S135-3) of setting a one-way or reciprocating welding condition based on the welding path set in the step (S135-2).

[0026] The above-mentioned tack welding conditions may include the tack welding path, tack welding parameters, the moving speed of the tack welding torch, the thermal characteristics of the tack welding portion, the effect of gravity on the tack welding portion at each tack welding position, the load of the hollow connecting member, the shrinkage stress of the tack welding portion after tack welding n times (n is an integer greater than or equal to 1), the thermal stress received by the tack welding portion during root welding, the shrinkage stress of the root weld portion after root welding, the shrinkage stress of the peeling and cap weld portion after peeling and cap welding, or a combination thereof.

[0027] In the above step (S140), multiple welding operations are performed under predetermined welding conditions, and the same steps as the above steps (S135-1) to (S135-3) may be performed continuously between the n times (n is an integer greater than or equal to 1) of welding operations and the n+1 times of welding operations.

[0028] In the above step (S140), the welding can be performed using the GMAW (gas metal arc welding) method.

[0029] The above handling robot may further include a grinder, and may further include a step (S145) of smoothly grinding the weld formed in the step (S140) using the grinder between the step (S140) and the step (S150).

[0030] An automatic welding method according to one embodiment of the present invention not only eliminates the need for additional welding groove processing for commercially supplied connecting members, but also shortens welding time, simplifies the welding process, reduces required manpower, and prevents welding defects.

[0031] FIG. 1 is a drawing for explaining an automatic welding method according to one embodiment of the present invention.

[0032] FIG. 2 is a drawing showing a portion of a pipe having a first welding groove formed therein and a portion of a hollow connecting member having a second welding groove formed therein as welded parts to be welded by an automatic welding method according to one embodiment of the present invention.

[0033] FIGS. 3a and 3b are drawings showing a gripper mounted on a handling robot used in an automatic welding method according to one embodiment of the present invention.

[0034] Figure 4 is a drawing showing a welding torch part of a welding robot, a gripper, a pipe, and a hollow connecting member gripped by the gripper.

[0035] Figure 5 is a drawing for explaining a method for fine alignment between a pipe and a hollow connecting member for a welding process.

[0036] Figure 6 is a drawing showing a welding process.

[0037] Figure 7 is a drawing for explaining the grinding process.

[0038] Figure 8 is a drawing showing a handling robot equipped with a gripper and a grinder and a hollow connecting member gripped by the handling robot.

[0039] Hereinafter, a welding groove forming method and a hollow member according to one embodiment of the present invention will be described in detail with reference to the drawings.

[0040] In this specification, "welding groove" means a machined portion formed between base materials (i.e., pipes, hollow connecting members, and hollow members) to be welded for efficient welding. Specifically, "welding groove" is a concept that collectively refers to all cut surfaces formed on the inner wall, side wall, and outer wall of one or both ends of each base material.

[0041] Also, in this specification, “welding station” means a place where welding equipment is installed.

[0042] Also, in this specification, the term "hollow member" refers to a member having a through hole extending from one end of the member to the other end. Specifically, the hollow member is a general term for pipes, 2D spools, and hollow connecting members.

[0043] Also, in this specification, “side end of a hollow member” means an end of a hollow member that is at the entrance or exit side of a through hole.

[0044] In addition, in this specification, the "fit-up sensor" and the "laser vision sensor" are characterized by having a function of obtaining 3D coordinates (three-dimensional coordinates) by scanning a hollow member (specifically, a welding groove). The fit-up sensor and the laser vision sensor may be mounted on the same robot or on different robots. In addition, the fit-up sensor and the laser vision sensor may be sensors with the same or different configurations and functions.

[0045] Also, in this specification, "2D spool" means a member manufactured by welding one non-welded hollow member to another non-welded hollow member. When manufacturing a 2D spool, the circumferential joint positions of each of the hollow members to be welded do not need to be specified.

[0046] Also, in this specification, "3D spool" means a member manufactured by welding one or more welded hollow members (including a 2D spool) and / or one or more unwelded hollow members to a 2D spool. When manufacturing a 3D spool, the circumferential joining positions of each of the welded members may or may not be specified.

[0047] Also, in this specification, “fit-up position” means a position where the welding grooves of two members are aligned with each other.

[0048] Also, in this specification, “fit-up or alignment” means bringing two members into close contact with each other so that their central axes coincide with each other.

[0049] Also, in this specification, tack welding means primary welding performed on a welding groove.

[0050] Also, in this specification, “root welding” means secondary welding performed on a welding groove after tack welding.

[0051] Also, in this specification, “filling and cap welding” means finishing welding performed on a welding groove after root welding.

[0052] FIG. 1 is a drawing for explaining an automatic welding method according to an embodiment of the present invention, FIG. 2 is a drawing showing a part of a pipe (PP) having a first welding groove (WG1) formed and a part of a hollow connecting member (CM) having a second welding groove (WG2) formed as a welded object to be welded by an automatic welding method according to an embodiment of the present invention, FIGS. 3a and 3b are drawings showing a gripper (GRP) mounted on a handling robot used in an automatic welding method according to an embodiment of the present invention, FIG. 4 is a drawing showing a welding torch part (WDTC) of a welding robot (WDRB), a gripper (GRP), a pipe (PP), and a hollow connecting member (CM) gripped by the gripper (GRP), FIG. 5 is a drawing for explaining a method for fine alignment between a pipe and a hollow connecting member for a tack welding process, FIG. 6 is a drawing showing a tack welding process, FIG. 7 is a drawing for explaining a grinding process, and FIG. 8 is This is a drawing showing a handling robot (HDRB) equipped with a gripper (GRP) and a grinder (GRD) and a hollow connecting member (CM) gripped by the handling robot (HDRB).

[0053] Referring to FIGS. 1, 2, 4, 6 and 8, an automatic welding method according to one embodiment of the present invention includes the following steps.

[0054] (1) A step (S110) of transporting a pipe (PP) (i.e., a piping material) having a first welding groove (WG1) formed thereon and placing it in a fit-up position of a welding field (i.e., a 2D spool welding field). At this time, the pipe (PP) may be held and positioned by jaws or rollers (not shown) installed in the welding field.

[0055] (2) A step (S120) in which a handling robot (HDRB) transports a hollow connecting member (CM) having a second welding groove (WG2) formed thereon to the vicinity of a fit-up position of the welding site. Specifically, a control unit (not shown) determines a material to be welded and confirms a spool to be manufactured. For example, the control unit may select a fitting material or a flange material as the hollow connecting member (CM) to be welded to a pipe (PP). Thereafter, according to an instruction from the control unit, the handling robot (HDRB) transports the hollow connecting member (CM) having a second welding groove (WG2) formed thereon to the vicinity of a fit-up position of the welding site. The hollow member (CM) may include a fitting member such as an elbow, a reducer, or a tee, or a flange member.

[0056] (3) A step (S130) in which a fit-up sensor (not shown) measures the alignment status of the hollow connecting member (CM) with respect to the fit-up position of the welding machine, and based on the result, a handling robot (HDRB) moves the position of the hollow connecting member (CM) to align the pipe (PP) and the hollow connecting member (CM) with the welding grooves (WG1, WG2). The step (S130) may be repeatedly performed until the alignment status between the first welding groove (WG1) of the pipe (PP) and the second welding groove (WG2) of the hollow connecting member (CM) reaches a passing level. After the step (S130), the handling robot (HDRB) may be fixed in position while holding the hollow connecting member (CM) until the following step (S140) is performed (specifically, until the step (135-1) described below is performed).

[0057] (4) Step (S140) in which a welding robot (WDRB) performs tack welding on the aligned welding grooves (WG1, WG2). Conventionally, it was impossible to automatically tack weld a pipe (PP) and a hollow connecting member (CM), but the inventors of the present invention implemented automatic tack welding of a pipe (PP) and a hollow connecting member (CM) by applying various technologies described below.

[0058] (5) Step (S150) in which a welding robot (WDRB) performs root welding on the above-mentioned welded grooves (WG1, WG2).

[0059] (6) Step (S160) in which a welding robot (WDRB) performs peeling and cap welding on the root welded welding grooves (WG1, WG2).

[0060] In the above step (S110), the first groove (WG1) of the pipe (PP) and in the above step (S120), the second groove (WG2) of the hollow connecting member (CM) may be configured to be suitable for V-groove welding, as illustrated in Fig. 2. However, the present invention is not limited thereto, and the first groove (WG1) and the second groove (WG2) may be formed in other shapes.

[0061] Referring to Fig. 2, the first groove (WG1) of the pipe (PP) and the second groove (WG2) of the hollow connecting member (CM) may have a "V" shape in their side surfaces when they are close to each other. In Fig. 2, "T1" represents the upper surface of the first groove (WG1) of the pipe (PP), and "B1" represents the lower surface of the first groove (WG1) of the pipe (PP). Similarly, "T2" represents the upper surface of the second groove (WG2) of the hollow connecting member (CM), and "B2" represents the lower surface of the second groove (WG2) of the hollow connecting member (CM). In addition, "WS" represents a welding space, and "TWP (tack weld point)" represents a tack weld.

[0062] Referring to Fig. 8, the handling robot (HDRB) includes a gripper (GRP), and the gripper (GRP) can be configured to grip the hollow connecting member (CM) while being inserted into the hollow of the hollow connecting member (CM). If another gripper configured to grip only the outer surface of the hollow connecting member (CM) is used instead of the gripper (GRP), there is a problem that when gripping both small-diameter hollow connecting member (CM) and large-diameter hollow connecting member (CM), the jaw stroke is not sufficiently large, making it difficult for the welding robot (WDRB) to approach when gripping small-diameter hollow connecting members, and when the driving components such as linear components are enlarged in order to increase the jaw stroke, the weight and volume of the gripper increase, which significantly reduces the usability of the handling robot (HDRB).

[0063] Referring to FIGS. 3a and 3b, the gripper (GRP) may include a main body (BD) and three or more stepped jaws (JW).

[0064] The main body (BD) can extend in one direction. That is, the direction in which the main body (BD) extends can be the longitudinal direction of the main body (BD).

[0065] Three or more stepped jaws (JW) can be movably connected to one side (i.e., the tip) of the main body (BD). Specifically, the three or more stepped jaws (JW) can be spaced apart from each other at equal intervals (e.g., 120° intervals) and extend radially in a direction perpendicular to the direction in which the main body (BD) extends. In addition, the three or more stepped jaws (JW) can be retracted by moving their central ends closer to each other or extended by moving their central ends farther apart from each other. As an example, as illustrated in FIG. 3A, when the three or more stepped jaws (JW) are retracted by moving their central ends closer to each other, the gripper (GRP) can be inserted into the hollow of the hollow connecting member (CM). As another example, when three or more stepped joints (JW) are inserted into the hollow of a hollow connecting member (CM), the hollow connecting member (CM) can be gripped by a gripper (GRP) when the ends on the central side are moved away from each other and expanded, as shown in FIG. 3b.

[0066] Additionally, three or more stepped jaws (JW) can be configured such that the height of the steps increases from the edge toward the center. A gripper (GRP) including stepped jaws (JW) configured in this manner can grip hollow connecting members (CM) of various sizes within a limited jaw stroke.

[0067] In addition, the gripper (GRP) can prevent deformation (twisting) of the hollow connecting member (CM) that occurs during welding by including three or more jaws (JW) so that it can stably respond to complex stresses, and because it is a method of gripping the hollow connecting member (CM) while inserted into the hollow of the hollow connecting member (CM), it can more strongly withstand changes that occur in the second groove (WG2).

[0068] In addition, by setting the gripper (GRP) to maintain this holding method from the start to the end of the welding, a stable automatic welding process can be implemented from start to finish.

[0069] In addition, the positions of the handling robot (HDRB) and the welding robot (WDRB) were set to the optimal path so that the handling robot (HDRB) equipped with the gripper (GRP) could prevent and avoid interference with the welding robot (WDRB) while the hollow connecting member (CM) was gripped by the gripper (GRP).

[0070] In addition, for precise welding, a welding torch cleaner (not shown) can be used at the end of each welding operation to maintain the cleanliness of the inside of the welding torch (WDTC) and the welding wire (not shown).

[0071] In addition, all tack welds can be implemented with optimal shapes and optimal deposition amounts to prevent quality problems (pores and poor penetration) during root welding. At this time, the tack weld locations are determined by scanning the first welding groove (WG1) and the second welding groove (WG2) with a laser vision sensor (LVS) mounted on the welding robot (WDRB), and then, based on the results, the welding robot controller (not shown) performs 7-axis control to stably perform welding from the back bead of the root weld to the cap welding without quality problems (Visual / RT) during root welding and peeling and cap welding.

[0072] As a result, the gripper (GRP) having the above configuration can minimize gripping failure and slip due to the ellipticity and tolerance of the hollow connecting member (CM) when gripping the hollow connecting member (CM).

[0073] The fit-up sensor used in the above step (S130) may be mounted on a welding robot (WDRB).

[0074] The tack welding performed in the above step (S130) serves to fix the fitted pipe (PP) and the hollow connecting member (CM) by short welding. At this time, the fixing level of the pipe (PP) and the hollow connecting member (CM) must be sufficient to withstand the load of the hollow connecting member (CM), taking into account the shape and weight of the hollow connecting member (CM). Although the tack welding is a short welding, in reality, the welding conditions equivalent to those of the main welding (root welding and peeling and cap welding) must be reflected.

[0075] Referring to FIG. 6, the welding robot (WDRB) may include a laser vision sensor (LVS). Furthermore, the laser vision sensor (LVS) and the fit-up sensor used in step S130 may be the same or different.

[0076] In addition, the automatic welding method may further include a step (S135-1) in which, between the steps (S130) and (S140), a gap and a height difference between a first groove (WG1) of a pipe (PP) and a second groove (WG2) of a hollow connecting member (CM) are measured through a laser vision sensor (LVS), and a handling robot (HDRB) that receives the gap and height difference from the laser vision sensor (LVS) moves the hollow connecting member (CM) so that the gap and height difference are adjusted to an allowable gap range and height difference range, respectively, thereby finely aligning the pipe (PP) and the hollow connecting member (CM) with respect to the welding grooves (CM1, CM2).

[0077] The above allowable gap range and height difference range may be 2 to 3 mm and 1.5 mm or less, respectively.

[0078] In the above step (S135-1), the gap and height difference between the first groove (WG1) of the pipe (PP) and the second groove (WG2) of the hollow connecting member (CM) are measured at three or more different points on the circumference of the first groove (WG1) of the pipe (PP) using 3D coordinates on the lower surface of the first groove (WG1) ((x11, y11, z11), (x12, y12, z12), (x13, y13, z13), etc.); And the 3D coordinates corresponding to each of these may be obtained by obtaining three or more gaps ((x21-x11), (x22-x12), (x23-x13) etc.) and three or more height differences ((z21-z11), (z22-z12), (z23-z13) etc.) from the 3D coordinates ((x21, y21, z11), (x22, y22, z22), (x23, y23, z23) etc.) on the lower surface of the second groove (WG2) of the hollow connecting member (CM) measured at three or more different points on the circumference of the second groove (WG2), and then averaging each of these.

[0079] The above 3D coordinates ((x11, y11, z11), (x12, y12, z12), (x13, y13, z13), (x21, y21, z11), (x22, y22, z22), (x23, y23, z23), etc.) can be measured by a laser vision sensor (LVS). Specifically, as illustrated in FIG. 5, the laser vision sensor (LVS) can generate the above-described 3D coordinates by irradiating a laser (LS) onto a pipe (PP) and a hollow connecting member (CM) so as to simultaneously penetrate them.

[0080] In addition, the automatic welding method generates 3D coordinates ((x11', y11', z11'), (x12', y12', z12'), (x13', y13', z13') etc.) on the lower surface of the first groove (WG1) of the pipe (PP) along the circumference of the first groove (WG1) through a laser vision sensor (LVS) between the steps (S135-1) and (S140), and also generates 3D coordinates ((x21', y21', z11'), (x22', y22', z22'), (x23', y23', z23') etc.) on the lower surface of the second groove (WG2) of the hollow connecting member (CM) along the circumference of the second groove (WG2), and utilizes the generated 3D coordinates. A step (S135-2) of setting a welding path may be further included. The welding path may be a linear or closed curve (e.g., circular) having the same starting point and ending point. In practice, welding may be performed at multiple points along the welding path.

[0081] In addition, the automatic welding method may further include a step (S135-3) of setting a one-way or reciprocating welding condition based on the welding path set in the step (S135-2).

[0082] The above tack welding conditions may include the tack welding path, tack welding parameters (current, voltage, position of the welding torch, feed speed of the welding electrode, etc.), moving speed of the tack welding torch, thermal characteristics of the tack welding portion, the effect of gravity on the tack welding portion at each tack welding position (the tack welding process from the 4 o'clock to the 8 o'clock direction, where tack welding is difficult due to the effect of gravity, is processed with the tack welding conditions secured in advance. In other words, verification is completed regarding how much force should be used to lift the tack welding portion upward), the load of the connecting member, the shrinkage stress of the tack welding portion after tack welding n times (n is an integer greater than or equal to 1), the thermal stress (energy (kJ)) received by the tack welding portion during root welding, the shrinkage stress of the root weld after root welding, the shrinkage stress of the peeling and cap weld after peeling and cap welding, or a combination thereof. The load of the connecting member may include a static load (load when not moving) and a dynamic load (load when moving, such as when rotating).

[0083] With regard to the shrinkage stress of the above-mentioned tack weld, root weld, and fill-and-cap weld, the correlation between the number of welding times and the amount of deposited material and the shrinkage stress by welding type is established and verified in advance, and data that can offset the shrinkage stress for each weld is secured in advance and applied at each welding, thereby maintaining the fit-up state well after tack welding. In particular, in order to prepare for the dynamic load impact that occurs more severely as the weight of the hollow connecting member (CM) increases, the program of the control unit can be configured to enable the release of the grip after the initial tack welding and the performance of additional tack welding.

[0084] The external forces that must be withstood during the above welding are (i) the static load and dynamic load of the hollow connecting member (CM), (ii) shrinkage stress during root welding, and (iii) thermal stress that can connect the weld during root welding. Optimal welding conditions that take into account the correlation between (i) and (iii) can be established and applied to the above welding process.

[0085] The above step (S140) can be performed using an all-position welding method in a state where the pipe (PP) is fixed at the fit-up position of the welding site and the hollow connecting member (CM) is gripped by a handling robot (HDRB).

[0086] In the above step (S140), multiple tack weldings can be performed under predetermined tack welding conditions. Specifically, in the above step (S140), the same steps as in the above steps (S135-1) to (S135-3) can be performed continuously between n tack weldings (n is an integer greater than or equal to 1) and n+1 tack weldings.

[0087] In the above step (S140), the tack welding can be performed by the GMAW (gas metal arc welding) method. In the past, the first-pass welding such as tack welding had to be performed by the GTAW (gas tungsten arc welding) method, which has a relatively slow welding time. This was because it was considered an inevitable choice when a gap existed between the welding grooves of two members, as in V-groove welding. However, the inventors of the present invention have, for the first time in the relevant technical field, implemented the first-pass welding such as tack welding by the GMAW method, which has a relatively fast welding time, rather than the GTAW method, which has a relatively slow welding time, by reflecting the welding conditions secured in advance and generating an appropriate weld melt according to the moving speed of the welding torch (WDTC). However, the present invention is not limited thereto, and the tack welding process can also be performed by the GTAW method.

[0088] The handling robot (HDRB) may further include a grinder (GRD). In this case, the automatic welding method may further include a step (S145) of smoothly grinding the weld formed in step (S140) using the grinder (GRD) between step (S140) and step (S150).

[0089] Referring to FIG. 7, the step (S145) may grind the protrusion-containing weld portion (TWP) formed in the welding grooves (WG1, WG2) illustrated in FIG. 7 (a) with a grinder (GRD) to form a smooth ground weld portion (GTWP) as illustrated in FIG. 7 (b). The ground weld portion (GTWP) illustrated in the upper part of FIG. 7 (b) is a side view, and the ground weld portion (GTWP) illustrated in the lower part is a plan view.

[0090] The above steps (S150) and (S160) can be performed in a flat position welding method through welding seam sensing by a laser vision sensor (LVS) and welding machine control (i.e., welding torch) in a state where the pipe (PP) and the hollow connecting member (CM) are tack-welded and the grip by the handling robot (HDRB) is released.

[0091] The above-described tack welding, root welding and peeling and cap welding can be performed automatically without manual intervention due to the individual actions and interactions of the handling robot (HDRB) and the welding robot (WDRB).

[0092] In addition, the automatic welding method may further include, after the step (S160), steps of manufacturing a 3D spool by performing the same steps as the steps (S110) to (S160) on a 2D spool manufactured by the automatic welding method and another hollow connecting member (CM).

[0093] While the present invention has been described with reference to the drawings, these are merely exemplary, and those skilled in the art will understand that various modifications and equivalent implementations are possible. Therefore, the true scope of technical protection of the present invention should be determined by the technical spirit of the appended claims.

[0094] [Explanation of symbols]

[0095] PP: Pipe CM: Hollow connecting member

[0096] T1, T2: Groove top surface B1, B2: Groove bottom surface

[0097] WG1, WG2: Welding groove WS: Welding space

[0098] WM: Welding melt GRP: Gripper

[0099] BD: Body JW: Joe

[0100] WDRB: Welding Robot LVS: Laser Vision Sensor

[0101] WDTC: Welding Torch LS: Laser

[0102] TWP: Tack weld GTWP: Ground tack weld

[0103] HDRB: Handling Robot GRD: Grinder

Claims

1. A step of transporting a pipe having a first welding groove formed thereon and placing it in a fit-up position of a welding site (S110); A step (S120) in which a handling robot transports a hollow connecting member having a second welding groove formed therein to the vicinity of a fit-up position of the welding site; A step (S130) in which a fit-up sensor measures the alignment status of the hollow connecting member with respect to the fit-up position of the welding machine, and based on the result, the handling robot moves the position of the hollow connecting member to align the pipe and the hollow connecting member with respect to the welding grooves; A step (S140) in which a welding robot performs tangible welding on the aligned welding grooves; A step (S150) in which the welding robot performs root welding on the weld grooves that have been welded; and An automatic welding method including a step (S160) in which a welding robot performs peeling and cap welding on the root-welded welding grooves.

2. In paragraph 1, An automatic welding method in which the first groove of the pipe in the step (S110) and the second groove of the hollow connecting member in the step (S120) are configured to be suitable for V-groove welding.

3. In paragraph 1, The above step (S140) is an automatic welding method performed in an all-position welding manner while each of the pipes is fixed at a fit-up position of the welding site and the hollow connecting member is gripped by the handling robot.

4. In paragraph 1, The above step (S150) and the above step (S160) are automatic welding methods performed in a downward-looking position welding manner while the pipe and the hollow connecting member are tangibly welded and the grip by the handling robot is released.

5. In paragraph 3, An automatic welding method in which the above handling robot includes a gripper, and the gripper is configured to grip the hollow connecting member while being inserted into the hollow of the hollow connecting member.

6. In paragraph 5, An automatic welding method in which the gripper comprises a main body extending in one direction and three or more stepped jaws movably coupled to one surface of the main body and spaced apart from each other at equal intervals and extending radially in a direction perpendicular to the direction in which the main body extends.

7. In paragraph 1, The above welding robot is an automatic welding method including a laser vision sensor.

8. In paragraph 7, An automatic welding method further comprising a step (S135-1) of measuring a gap and a height difference between the first groove of the pipe and the second groove of the hollow connecting member using the laser vision sensor between the steps (S130) and (S140), and having the handling robot receive the gap and the height difference from the laser vision sensor move the hollow connecting member so that the gap and the height difference are adjusted to an allowable gap range and a allowable height difference range, respectively, thereby finely aligning the welding grooves of the pipe and the hollow connecting member.

9. In paragraph 8, In the above step (S135-1), the gap and height difference between the first groove of the pipe and the second groove of the hollow connecting member are calculated by obtaining three or more gaps and three or more height differences from 3D coordinates on the lower surface of the first groove measured at three or more different points on the circumference of the first groove of the pipe, and 3D coordinates corresponding to each of these, and then averaging each of these.

10. In paragraph 9, An automatic welding method further comprising a step (S135-2) of generating 3D coordinates on the lower surface of the first groove of the pipe along the circumference of the first groove using the laser vision sensor, and also generating 3D coordinates on the lower surface of the second groove of the hollow connecting member along the circumference of the second groove, and setting a welding path using the generated 3D coordinates.

11. In paragraph 10, An automatic welding method further comprising a step (S135-3) of setting a one-way or reciprocating welding condition based on the welding path set in the above step (S135-2).

12. In Article 11, The above-mentioned tack welding conditions are an automatic welding method including the tack welding path, tack welding parameters, the moving speed of the tack welding torch, the thermal characteristics of the tack welding portion, the effect of gravity on the tack welding portion at each tack welding position, the load of the hollow connecting member, the shrinkage stress of the tack welding portion after tack welding n times (n is an integer greater than or equal to 1), the thermal stress received by the tack welding portion during root welding, the shrinkage stress of the root weld portion after root welding, the shrinkage stress of the peeling and cap weld portion after peeling and cap welding, or a combination thereof.

13. In paragraph 11, An automatic welding method in which, in the above step (S140), multiple welding operations are performed under predetermined welding conditions, and the same steps as in the above step (S135-1) to the above step (S135-3) are continuously performed between the n times (n is an integer greater than or equal to 1) of welding operations and the n+1 times of welding operations.

14. In paragraph 1, In the above step (S140), the automatic welding method in which the welding is performed using the GMAW (gas metal arc welding) method.

15. In paragraph 1, An automatic welding method, wherein the handling robot further includes a grinder, and further includes a step (S145) of smoothly grinding the weld formed in the step (S140) using the grinder between the step (S140) and the step (S150).

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