KR20210084988A - Apparatus for Robot Welding with Curved Part Welding Function and Method thereof - Google Patents

Abstract

The present invention relates to a robotic welding device capable of performing welding on a curved portion and a control method thereof, which can perform robotic welding on a right-angled curved portion or an acute-angled curved portion while maintaining a direction of forward feeding. The robotic welding device capable of performing welding on a curved portion in accordance with one embodiment of the present invention is a robotic welding device capable of performing welding on a curved portion, which performs welding on a right-angled curved portion or an acute-angled curved portion while maintaining a direction of forward feeding where a filler material is fed from the front side, wherein the robotic welding device comprises: a welding torch; a welding power supply unit for applying welding power to the welding torch; a 6-axis vertical multi-joint welding robot having a terminal where the welding torch is mounted; a 2-axis positioner for supporting a workpiece to be welded by the welding robot; and a filler material feeding device having a plurality of jobs stored therein and capable of changing conditions for welding only by changing a call number of a job.

Description

A robot welding device capable of welding a bent part and a control method thereof {Apparatus for Robot Welding with Curved Part Welding Function and Method thereof}

The present invention relates to a robot welding apparatus capable of welding a bent portion and a control method thereof, and more particularly, a robot welding apparatus capable of welding a bent portion capable of performing robot welding of a right-angle bent portion or abrupt bend portion while maintaining the overall broadcast-grade direction, and the same It relates to a control method.

The lamination method in metal AM is divided into powder and wire according to the material type. When powder is used as a material, lamination is mainly performed using a laser beam and an electron beam as heat sources. When a wire is used as a material, a laser, an electron beam, and a welding arc are used as heat sources for lamination. Metal AM based on powder has high precision, but has disadvantages in that the deposition rate is relatively low and production costs such as powder or heat source equipment are expensive. These features facilitate the manufacture of small precision metal parts. Wire-based metal AM has low precision, but is being used to manufacture various metal products based on low production cost and high welding speed.

Metal AM based on powder has been developed significantly mainly in Europe, so most of the technology is monopolized and the powder used is also limited. Compared to the existing processing method, powder-based metal AM has a higher production cost, so it is being applied to products for prototyping or product weight reduction.

Wire-based metal AM is growing mainly in the UK, US, Japan, and China, and it is advantageous for manufacturing expensive metal products such as Ti, Al, and Ni alloys based on low production cost. In particular, Ti alloy is a metal used for aviation, space, and national defense, and imports of bulk products are restricted, so there is interest in AM, a metal that can manufacture Ti alloy in medium to large size in various countries.

An object of the present invention is to provide a robot welding apparatus capable of welding a bent portion capable of performing robot welding of a right-angle bent portion or a sharp bend portion while maintaining the direction of the entire broadcast class, and a control method thereof.

In addition, the present invention uses Super-TIG welding in metal AM (Additive Manufacturing) to secure sound quality of wall surfaces and bead heights by developing interlocking teaching technology and process development between a robot and a positioner for right-angle bent parts that exist during lamination. An object of the present invention is to provide a metal lamination apparatus and method using super tig welding.

A robot welding apparatus capable of welding a bent portion according to an embodiment of the present invention is a robot welding apparatus capable of welding a bent portion for welding a right-angled portion or a sharp bend while maintaining a supply direction for supplying a filler metal from the front, comprising: a welding torch; a welding power supply for applying a welding message to the welding torch; 6-axis vertical articulated welding robot equipped with a welding torch at the end; a two-axis positioner for supporting a welding object to be welded by the welding robot; And it may include a filler metal feeding device that stores a plurality of JOBs and enables welding conditions to be changed only by changing the JOB call number when welding conditions are changed.

A control method of a robot welding apparatus capable of welding a bent portion according to an embodiment of the present invention is a control method of a robot welding apparatus capable of welding a bent portion for welding a right-angled bend or a sharp bend while maintaining the supply direction of supplying the filler metal from the front. , The robot welding device, a welding torch; a welding power supply for applying a welding message to the welding torch; 6-axis vertical articulated welding robot equipped with a welding torch at the end; a two-axis positioner for supporting a welding object to be welded by the welding robot; and a filler metal feeding device that stores a plurality of JOBs and enables welding conditions to be changed only by changing the JOB call number when welding conditions are changed, and determining whether the current welding section is a right-angled bend or an abrupt bend; Calling a pre-stored right angle bending part JOB or abrupt bending part JOB when the current welding section is a right angle bending part or a sharp bending part; and controlling the welding to be performed by the right-angled bent portion JOB or the abruptly bent portion JOB.

According to the robot welding apparatus capable of welding the bent portion of the present invention and the control method thereof, it is possible to perform robot welding of a right-angle bent portion or a sharp bend portion while maintaining the direction of the entire broadcast level.

In addition, by using Super-TIG welding in metal AM (Additive Manufacturing), it is possible to secure sound quality of wall and bead height by developing interlocking teaching technology and process between robot and positioner for right-angle bends that exist during lamination.

The following drawings attached to the present specification illustrate preferred embodiments of the present invention, and serve to further understand the technical spirit of the present invention together with the detailed description of the present invention, so the present invention is limited only to the matters described in those drawings and should not be interpreted.
The drawings are diagrams schematically showing a metal lamination apparatus and method using super tig welding according to an embodiment of the present invention.

Hereinafter, a preferred embodiment of the present invention will be described with reference to the drawings. In addition, the embodiments described below do not unreasonably limit the content of the present invention described in the claims, and the entire configuration described in the embodiments of the present invention cannot be said to be essential as a solution for the present invention. Components applied to one embodiment may be applied to other embodiments even if not specifically mentioned.

A robot welding apparatus capable of welding a bent portion and a control method thereof according to an embodiment of the present invention can perform robot welding of a right-angled bent portion or an abrupt bend portion while maintaining the direction of the entire broadcast level.

A robot welding apparatus capable of welding a bent portion according to an embodiment of the present invention is a robot welding apparatus capable of welding a bent portion for welding a right-angled portion or a sharp bend while maintaining a supply direction for supplying a filler metal from the front, comprising: a welding torch; a welding power supply for applying a welding message to the welding torch; 6-axis vertical articulated welding robot equipped with a welding torch at the end; a two-axis positioner for supporting a welding object to be welded by the welding robot; And it may include a filler metal feeding device that stores a plurality of JOBs and enables welding conditions to be changed only by changing the JOB call number when welding conditions are changed.

A control method of a robot welding apparatus capable of welding a bent portion according to an embodiment of the present invention is a control method of a robot welding apparatus capable of welding a bent portion for welding a right-angled bend or a sharp bend while maintaining the supply direction of supplying the filler metal from the front. , The robot welding device, a welding torch; a welding power supply for applying a welding message to the welding torch; 6-axis vertical articulated welding robot equipped with a welding torch at the end; a two-axis positioner for supporting a welding object to be welded by the welding robot; and a filler metal feeding device that stores a plurality of JOBs and enables welding conditions to be changed only by changing the JOB call number when welding conditions are changed, and determining whether the current welding section is a right-angled bend or an abrupt bend; Calling a pre-stored right angle bending part JOB or abrupt bending part JOB when the current welding section is a right angle bending part or a sharp bending part; and controlling the welding to be performed by the right-angled bent portion JOB or the abruptly bent portion JOB.

Arc welding is a method of joining welds with a heat source (about 5,000℃) generated by shield gas and arc discharge. It can be divided into consumable electrode types (SMAW, GMAW, SAW, EGW) and non-consumable electrode types (GTAW, PAW). have.

Tungsten Inert Gas Welding is also called Gas Tungsten Arc Welding (GTAW, Gas Tungsten Arc Welding). It uses an inert gas such as Ar or He as a shielding gas and an arc generated between the non-consumable tungsten electrode and the base material. It refers to a welding method in which the base material is melted and joined by heat. This welding method can be applied to all welding positions, and since the arc is very stable and the quality of the weld is excellent, it is used when it is difficult to weld and cover arc welding of metals sensitive to oxidation or nitridation, but compared to gas metal arc welding, Since the welding speed is slow, productivity is low.

TIG welding is a method of welding welds by arc heat generated between a non-consumable tungsten electrode and a base metal. As in 2.1, it is a method of welding while using an inert gas (Ar, He, etc.) as a protective gas around the welding part.

The current TIG welding machine power supply is AC or DC with constant current characteristics. At this time, the selection of AC or DC power source depends on the required welding characteristics and the material of the base metal. For example, some metals weld more easily when welded with AC power, while some metals can achieve better results when welded with DC power. The characteristics of welding with AC and DC power are as follows.

1) DCEN (Direct Current Electrode Negative), high current can be used even with a welding rod of the same size, so penetration is deep, welding speed can be increased, and the bead width is narrow. Also called DC Straight Polarity.

2) DCEP (Direct Current Electrode Positive), rarely used, but used for welding thin plates of Al, Mg, etc. in special cases. ① Due to the large amount of heat generated by the welding rod, there is a risk that the tip of the welding rod may melt, so use a welding rod with a diameter 4 times larger than that of the DCEN welding rod at the same current. ② There is a cleaning action when using argon as a shielding gas.

3) Alternating current (AC), ① Add high-frequency power to use. ② Penetration and bead width are intermediate between DCEN and DCEP. ③ The cleaning action takes place about half of that of DCEP.

The advantages are: TIG welding is very good for thin plate welding because it is easy to adjust the welding heat input. Since the tungsten electrode is non-consumable, it can be welded by melting the base metal by arc heat without adding filler metal and can be used for welding almost all metals. However, it is not used for welding low-melting-point metals, such as lead, tin, or alloys of tin. The mechanical properties of the weld are excellent. Excellent corrosion resistance. Since no flux is required, it is easy to weld non-ferrous metals. Because the protective gas is transparent, the operator can understand the welding status well. All-position welding is possible by minimizing welding spatter. There is little deformation of the weld joint.

Disadvantages include: In general, when TIG welding can be easily welded by methods such as SMAW, SAW, GMAW, etc., there are cases in which the overall price increases to the extent that it cannot compete with these welding methods in terms of cost. The welding speed is slower than the welding method using a consumable electrode. If the tungsten electrode melts or becomes contaminated with the welding part due to welding error, the welding part is easily brittle. If the tip of the filler metal is exposed to air due to improper welding technique, the weld metal will be contaminated. Inert gas and tungsten electrodes are expensive compared to other welding methods. Compared to other welding methods such as SMAW, the welding machine is expensive.

In the conventional TIG welding, the arc was regarded as a plasma column, and a thin and round wire was supplied by considering the specific surface area as important. However, in the new plasma stream theory, the plasma was regarded as a fluid from the upper tungsten electrode to the molten pool, and the theoretical system was established by modeling the arc physics characteristic of the plasma stream.

Based on this theory, super-TIG welding technology with dramatically improved productivity was developed by designing and applying the filler metal shape as a plate concave in the electrode direction so that it is perpendicular to the plasma stream. Fig. 2.2 shows the arc plasma column of the conventional TIG arc concept, and Fig. 2.3 shows that the arc is regarded as a fluid in which plasma flows from the upper tungsten electrode to the molten pool by the plasma stream theory.

When the new plasma stream theory is applied, it can be seen that the conventional wire 1.2mm has a convex wire surface, making it difficult to enter the plasma stream, and the incident area of the plasma stream to the wire is very small with a small diameter. However, it can be seen that the newly developed C-Filler has an upper concave shape, so that the incidence of the plasma stream is advantageous, and the incident area of the plasma stream is also very wide. Fig. 2.4 shows the plasma stream incident area for a 1.2mm wire by plasma stream theory, and Fig. 2.5 shows the plasma stream incident area to the C-Filler according to the plasma stream theory.

Additive manufacturing refers to the process of directly stacking CAD models into products, and is also called rapid manufacturing or 3D printing. The purpose of AM is to build a product in a desired shape or similar to a desired shape by successively stacking layers and layers. Each layer receives a shape from CAD data and is fused through a heat source. When the material used is made of metal, it is called metal additive manufacturing.

As mentioned in the introduction, additive manufacturing can be classified according to the shape of the material being added, and it is divided into a powder supply method and a wire supply method. Table 2.1 shows the classification of additive manufacturing.

Selective laser sintering is the first commercialized powder bed process, developed and patented by Austin of the University of Texas in 1989. It is a technique for selectively heating and sintering powder using a high-power laser to produce a desired shape. After selectively sintering the applied powder layer through a laser, the next powder layer is applied again and sintering with a laser is repeated. A method of laminating in this way is a laser sintering method. The powder used is expensive. Currently, it is mainly used for the production of prototypes, the production of medical supplies, and the production of electronic parts, taking advantage of its high precision. It is also advantageous for high-priced, small-lot, multi-variety production. Fig. 2.6 shows a schematic diagram of metal additive manufacture by laser sintering.

Laser melting (Selective laser melting) is a process of completely melting a powder using a higher laser energy density compared to a laser sintering process. At this time, in order to completely melt the powder, it is essential to prevent oxidation of the molten part. Like the laser sintering method, it is a method of manufacturing a product by applying powder and selectively melting it with a laser. Fig. 2.7 shows a schematic diagram of the laser melting method.

Laser powder deposition is a process that uses a laser beam to form a molten pool on a metal substrate to which powder is supplied. Unlike laser sintering and laser melting, a flow of powder is formed through a nozzle to supply powder. Fig. In 2.8, a schematic diagram of the laser welding method is shown.

Electron beam melting is a process of completely melting coated powder using a high energy density, such as a laser melting method. Since it is melted in a high vacuum chamber, there is no need to worry about oxidation of the molten metal. Like the laser melting method, it is a method of manufacturing a product by applying powder and selectively melting it with a laser. Compared to the laser melting method, it has the advantage of low thermal stress. Fig 2.9 shows a schematic diagram of the electron beam melting method. In the laser-wire feed process, the metal additive is not powder, but wire is used, and a laser is used as a heat source to melt it. Compared to processes using powder, the loss of filler metal is small and the fast welding speed is the advantage, but the welding speed is lower than the metal AM using electron beam or welding arc as heat source. Fig. 2.10 shows a schematic diagram of the laser-wire feed process.

Electron beam additive manufacturing is a process that uses an electron beam as a heat source and wire as a filler metal. The electron beam has an advantage in that the thermal stress is small because the thermal gradient is smaller than that of the laser. It is different from the normal electron beam, and products with more complex shapes can be stacked through the moving head. However, since a vacuum chamber must be used, the price of the device is very high. Fig. In 2.11, a schematic diagram of electron beam additive manufacturing is shown.

Arc wire-feed process is a metal additive manufacturing process by melting a wire using an arc as a heat source. In the case of MIG or GMAW, it has the advantage of a fast production speed based on a relatively high welding speed, and in the case of TIG welding and Plasma Arc Welding (PAW), it has a relatively low welding speed but good welding quality. Fig. In 2.12, schematic diagrams of MIG, GMAW, GTAW and PAW are shown.

Experiments for developing bead start and end junction solutions are described below. This experiment defined the flatness and parameters for evaluating the bead height of the connection part when welding the connection part using a C-Filler made of STS 316L material. In addition, based on this, the process development of the connection part with appropriate quality was conducted, and the welding quality was confirmed through cross-sectional analysis. Bead connection parameter definition, flatness means the quality of the connection from the beginning to the end of the bead. For example, if the flatness is positive, the bead height of the joint is higher than the normal bead height. In this study, the appropriate flatness range was set to +1 mm. Fig. 3.1 shows a schematic diagram defining the flatness, a parameter for evaluating the bead connection. _{Definition of D BS} from the bead start connection, the bead start connection means the part that starts welding from the weld crater and connects the weld. D _BS (Back Step Distance) was defined as the distance from the start of welding at the bead crater to the starting position of the current up-slope. Fig. 3.2 is a schematic view showing the definition of D _BS Fig. 3.3 is a schematic diagram showing the current up-slope according _{to D BS.}

_{Definition of D BO} in the bead termination connection part, the bead termination connection part means the part that connects the welding part while terminating the welding to the welding start point. D _BO (Bead Overlap Distance) was defined as the distance from the starting point of the bead to the stop of feeding. At this time, the current has a down-slope and gradually decreases. Fig. 3.4 is a schematic diagram showing the definition _{of D BO, and Fig.} 3.5 is a schematic diagram showing the current down-slope according _{to D BO.}

T _FUS (Feeding Up Slop Time) Definition, T _FUS was defined as the time it takes for the feed rate to reach the set feed speed from 0 cpm after the filler metal feed start signal. For example, if the set supply speed is 100 cpm and T _FUS is set to 3 seconds, the supply speed increases over 3 seconds from 0 cpm to 100 cpm after the supply start signal. Fig. 3.4 is _{a schematic diagram showing the definition of T FUS} , and the supply speed increases as shown in the red box.

T _FDS (Feeding Down Slop Time) Definition, T _FDS was defined as the time it takes to reach 0 cpm from the set supply speed after the filler metal supply stop signal. For example, if the set feeding speed is 100 cpm and T _FDS is set to 3 seconds, the feeding speed decreases from 100 cpm to 0 cpm over 3 seconds after the stop signal. As _{a schematic diagram showing the definition of T FDS,} the supply speed decreases as shown in the red box.

Bead start connection test method, Fig. 3.9 is a schematic diagram of experimental preparation. The moment when the connection part is welded was recorded as a video using a welding camera. In addition, the experiment was conducted by measuring the current and voltage waveforms output during welding using the welding monitoring system. The moment when the connection part is welded was recorded as a video using a welding camera. Table 3.3 shows the experimental conditions. Experiments were conducted with T _FUS of 1, 3, 5, and 7 seconds at weld cross-sections of 20, 40, and 60 mm ^{2 .}

Consideration of the appearance, longitudinal section and flatness of the bead start connection according to T _FUS ^{, welding cross-sectional area of 20 mm 2} , Table 3.4 shows the bead appearance, longitudinal cross-section and flatness according to T _FUS ^{at 20 mm 2 of welding cross-section.} At T _FUS 1 and 2 seconds, the appropriate flatness range was satisfied, and at 5 and 7 seconds, the bead height was low and not satisfied.

Welded cross-sectional area of 40 mm ² , Table 3.5 shows the bead appearance, longitudinal cross-section and flatness according to T _FUS in a welded cross-sectional area of 40 mm ^{2 .} At T _FUS 1 and 2 seconds, the appropriate flatness range was satisfied, and at 5 and 7 seconds, the bead height was low and not satisfied.

Welded cross-sectional area of 60 mm ² , Table 3.6 shows the bead appearance, longitudinal cross-section, and flatness according to T _FUS in a welded cross-sectional area of 60 mm ^{2 .} In the case of this experiment, the bead height was not satisfactory in _{all ranges of T FUS.}

Comparison of flatness of bead start connection according to T _{FUS, Fig.} 3.3 is a graph comparing flatness according to T _FUS in welding cross-sectional areas of 20, 40, and 60 mm ^{2 .} When T _FUS was 1 and 3 seconds, the appropriate flatness range was satisfied at the welding cross-sectional area of 20 and 40 mm ^{2 .} On the other hand, in the welding cross-sectional area of 60 mm ² , the appropriate flatness range was not satisfied in all ranges of T _FUS.

Consideration of lack of flatness, Fig. 3.4 is a graph showing the cooling rate of the welding part according to the amount of heat input. As can be seen from the graph, when the amount of heat input is large, the solidification of the molten pool is delayed. As a result, the length of the crater, which is the last part of the welding, becomes longer, and the length of the connection part becomes longer. Therefore, if the amount of heat input is large, it is necessary to increase the _{D BS of the bead start connection part for welding.}

Sequence control at the bead start connection, Fig. 3.4 is a schematic diagram showing sequence control with waveforms measured when welding the bead start connection part. When welding starts for the first time, only the arc fires without feeding filler metal to secure penetration, and then, when the connection is started, it is possible to secure welding by gradually feeding the filler metal. Such a method is not possible in consumable electrode welding such as GMAW and FCAW. On the other hand, non-consumable electrode welding such as GTAW is possible because current and filler metal supply can be controlled independently.

Bead termination connection test method, Fig. 3.6 is a schematic diagram of experimental preparation. The experiment was conducted by measuring the current and voltage waveforms output during welding using the welding monitoring system. In addition, using a welding camera, the moment when the joint is welded was recorded as a video. Table 3.3 shows the experimental conditions. Experiments were carried out with T _FDS of 1, 3, 5, and 7 seconds at weld cross-sections of 20, 40, and 60 mm ^{2 .}

Consideration of the appearance, longitudinal section and flatness of the bead termination connector according to T _FDS ^{, welding cross-sectional area of 20 mm 2} , Table 3.7 shows the bead appearance, longitudinal cross-section and flatness according to T _FDS ^{at 20 mm 2 of welding cross-section.} At T _FDS 3, 5, and 7 seconds, the appropriate flatness range was satisfied, and at 1 second, the bead height was low and not satisfied.

Welded cross-sectional area of 40 mm ² , Table 3.8 shows the bead appearance, longitudinal cross-section and flatness according to T _FDS in a welded cross-sectional area of 40 mm ^{2 .} At T _FDS 3, 5, and 7 seconds, the appropriate flatness range was satisfied, and at 1 second, the bead height was low and not satisfied.

Welded cross-sectional area of 60 mm ² , Table 3.10 shows the bead appearance, longitudinal cross-section and flatness according to T _FDS in a welded cross-sectional area of 60 mm ^{2 .} At T _FDS 3, 5, and 7 seconds, the appropriate flatness range was satisfied, and at 1 second, the bead height was low and not satisfied.

Comparison of flatness of bead termination connection according to T _{FDS, Fig.} 3.11 is a graph comparing flatness according to T _FDS at weld cross-sections of 20, 40, and 60 mm ^{2 .} When T _FDS was 3, 5, and 7 seconds, the appropriate flatness range was satisfied at the weld cross-sectional area of 20, 40, and 60 mm ^{2 .} On the other hand, when T _FDS was 1 second, the appropriate flatness range was not satisfied in all weld cross-sectional areas.

Sequence control at the bead termination connection, Fig. 3.12 is a schematic diagram showing sequence control with waveforms measured during welding of the bead termination connection. At the end of welding, arc firing and filler metal supply are performed at the start point of the bead to secure penetration and welding, and the current down-slope is made from the end of the end connection part, and only the arc is fired without filler metal supply to secure penetration, and then welding is finished. Such a method is not possible in consumable electrode welding such as GMAW and FCAW. On the other hand, non-consumable electrode welding such as GTAW can control current and filler metal supply independently, so it is possible to prevent defects and secure a constant bead height at the bead connection.

In order to develop a bead connection solution with no defects and uniform bead height in Super-TIG welding, the following conclusions were obtained through experiments. 1) As a result of testing the bead start connection using a feeding device with added up-slope and down-slope functions, when T _FUS was 1, 3 seconds, the welding cross-sectional area of 20, 40 mm ² satisfies the appropriate flatness range. , at a welding cross-sectional area of 60 mm ² , the crater length increased due to a large amount of heat input, which was not satisfactory. 2) If the amount of heat input is large, it can be solved by increasing the back step distance. 3) As a result of the bead termination connection test, the appropriate flatness range was satisfied at the weld cross-sections of 20, 40, and 60 mm ² _{except when T FDS = 1 second.}

Hereinafter, an experiment for developing a right-angled bend process in metal AM by super-TIG welding will be described. In this experiment, the robot-positioner control algorithm for the part where the weld bead is bent vertically by using a C-Filler made of Inconel 625 and an arc heat source, and the flow of the wall bead was considered. Through this, it was confirmed that the quality of the right angle bend and the wall with improved quality in metal AM. The test materials are shown in Tables 4.1 and 4.2.

Experimental method, Fig. 4.2 is a 3D schematic diagram of a laminate to be laminated. The shape is a letter D in the alphabet and stacked in 1 layer 5 pass. Since the welding is not stopped every 1 pass, there is a bead termination connection and there is a vertical bend that bends vertically. Fig. 4.3 is a cross-sectional schematic diagram of the laminate. In the upper layer, which is the last part of the stack, it is reduced to 1 layer 3 pass and 1 layer 1 pass, and the shape is gradually narrowed. Table 4.3 shows the lamination test conditions.

Fig. 4.4 is a photograph showing the experimental equipment. For the experiment, TIG power was used and C-filler was used as filler material. The robot and the positioner are interlocked and can be operated together, making them suitable for metal AM.

Fig. 4.5 is a schematic diagram showing the welding signal sequence during welding. This is a picture of the experimental equipment. The welding signal is transmitted from the robot to the feeder by first pressing the start button on the robot's pendant. Then, when the feeder receives a welding signal from the robot, it supplies the set supply condition and simultaneously transmits the welding signal under the set welding condition to the welding machine. Finally, the welder receives the welding signal from the feeder and performs welding.

Experimental results and considerations are as follows. Fig. 4.6 is a schematic diagram to explain the welding pass and right angle bend algorithm. Among the 5 passes, it is pass 1 from the inside and is marked as P1. Super-TIG's C-filler has a C-shaped cross-section and can be welded at a high welding speed when feeding forward or backward. However, since the C-filler has a strong rigidity, there is a problem of poor feeding when the torch, which is the feeding side, rotates. To overcome this, in the right angle bend, the robot with the torch did not rotate, but only the positioner rotated and welded, which means that the welding speed is 0 cpm. At this time, while the positioner rotates, the torch has to stop along the same position of the right angle bend, so the current and supply speed are lowered. It also requires a larger weld cross-section on the outside than on the inside of the right-angled bend.

Process variable control at right angle bends, Fig. 4.7 is a graph showing each process variable changing at the right angle bend. At the right angle bend, the torch maintains the same position along the rotation of the positioner, and since the welding speed is 0 cpm, the welding cross-section is properly maintained by reducing the current and supply speed. The robot and the positioner move in conjunction with each other. Therefore, when the rotation angle of the positioner is 0 degrees, the coordinates of the robot become (0, 0), and as the positioner rotates up to 90 degrees, the coordinates of the robot also draw an arc, and there is a problem that it extends up to (128, 103). To overcome this, in the right angle bend, the robot with the torch did not rotate, but only the positioner rotated and welded. At this time, while the positioner rotates, the torch has to stop along the same position of the right angle bend, so the current and supply speed are lowered. It also requires a larger weld cross-section on the outside than on the inside of the right-angled bend.

Fig. 4.8 is a photograph of the appearance of the laminate. In d) and e), it can be seen that the wall of the high-rise part flows down less than the wall of the low-rise part based on the middle part of the bead height. In the case of the high-rise part, the welding speed of the wall pass was laminated at 1.5 kg/h, and in the low-rise part, the welding speed of the wall pass was laminated at 3 kg/h.

A study of wall bead flow, Fig. 4.9 is a photograph comparing the low-rise part and the high-rise part of the laminate. a) In the case of the lower layer in the photo, P1 and P5, which are wall passes, have the same large welding cross-sectional area as P2, 3, and 4, which are internal passes. Therefore, the amount of liquid metal was large, and severe flow occurred. In the case of the high-rise part, the wall pass reduced the welding cross-sectional area by half, and accordingly, it was possible to obtain a good wall surface by preventing dripping. If the wall bead flows down from the metal AM, the height of the bead in that part will be lowered, which may result in a non-uniform lamination as a whole. b) is a photograph of the wall of the vertical bend. In the vertical bending part, a) flow was more severe than the straight part in the photo. This is thought to be because the welding speed becomes 0 cpm while the positioner is rotating and the solidification of the liquid metal is delayed due to the large amount of heat input compared to the straight part.

Wall bead flow model, Fig. 4.10 is a schematic diagram showing the flow-down modeling of the wall bead. F _g is the gravity, F _a is the arc force, and F _s is the surface tension of the liquid metal. If the surface tension of the liquid metal is less than the sum of the arc force and gravity, the wall bead will flow down. This can be expressed as an inequality as follows.

F _a + F _g > F _s → Flowing of the wall bead occurs

F _a + F _g < F _s → No flow of wall beads

Fig. 4.11 is a picture comparing the oxidation degree of the wall bead and the inner bead. As a method to prevent spillage, using the wall-first lamination method, the layers were laminated in the order of P1→P5→P2→P3→P4. During lamination, wall paths P1 and P5 conduct one-dimensional heat conduction, and internal paths P2, P3, and P4 conduct two-dimensional heat conduction and are cooled. Therefore, the cooling rate of the wall pass is slower than that of the inner pass, so it is thought that oxidation proceeded more.

F _a + F _g > F _s → Flowing of the wall bead occurs

F _a + F _g < F _s → No flow of wall beads

A study of dripping at right angle bends, Fig. A) of 4.12 is a schematic diagram showing the thermal conduction of P1 and P5 in the right-angled bent part of the laminate, and b) is a photograph comparing the flow down from the wall of the right-angled bent part. At right angle bends, the cooling rate is very slow due to the low solidification rate due to limited heat conduction and high heat input. Therefore, it can be seen that a more severe run-down occurred than in the straight part. In addition, it can be seen that P1, which is an inner wall pass of the laminate, is less prone to dripping than P5, which is an outer wall pass. In the case of P1, heat conduction occurs in a 270 degree direction, whereas in P5, heat conduction occurs in a 90 degree direction. Therefore, it is considered that the cooling rate of P5 is slower and more oxidized and the runoff is severe.

As a result of the experiment for the development of the right angle bend process in STAM (Super-TIG Additive Manufacturing) by Super-TIG welding, the following conclusions were obtained. 1) The welding signal sequence for automatic metal AM and its validity were verified. 2) In order to prevent spillage, it was laminated by the wall-first lamination method, and good quality was obtained by lowering the welding speed only on the wall side. 3) An algorithm was established to satisfy the required welding cross-sectional area for each pass in the right angle bend. 4) Oxidation due to low heat conduction occurred in P1 and P5, which are wall passes, and especially, the flow down due to the slow cooling rate at the right angle bend of P5 was severe. However, by reducing the welding cross-sectional area in the wall pass to 1/2 level, it was possible to prevent dripping.

As a result of the study on the development of the T-connection process in metal AM by Super-TIG welding, the following conclusions were obtained. 1) As a result of testing the bead start connection using a feeding device with added up-slope and down-slope functions, when T _FUS is 1, 3 seconds, the welding cross-section area of 20, 40 mm ² satisfies the appropriate flatness range. , at a welding cross-sectional area of 60 mm ² , the crater length increased due to a large amount of heat input, which was not satisfactory. 2) If the amount of heat input is large, it can be solved by increasing the back step distance. 3) As a result of the bead termination connection test, the appropriate flatness range was satisfied at the weld cross-sections of 20, 40, and 60 mm ² _{except when T FDS = 1 second.} 4) The welding signal sequence for automatic metal AM and its validity were checked. 5) In order to prevent spillage, it was laminated by the wall-first lamination method, and good quality was obtained by lowering the welding speed only on the wall side. 6) An algorithm was established to satisfy the required welding cross-sectional area for each pass in the right angle bend. 7) Oxidation due to low heat conduction occurred in P1 and P5, which are wall paths, and especially, the flow down due to the slow cooling rate at the right angle bend of P5 was severe. However, by reducing the welding cross-sectional area in the wall pass to 1/2 level, it was possible to prevent dripping.

On the other hand, an embodiment of the present invention is a device in which a plurality of JOBs in the feeder are stored, and when welding conditions are changed, welding conditions can be changed only by changing the JOB call number. The functions of the feeding device include feeding speed setting function, welding current setting function, feeding speed upslope setting function, feeding speed downslope setting function, rear inching speed and length setting function, all broadcast-stop time setting function, all broadcasting grade - It is possible to provide a filler metal feeding device with a plurality of welding conditions with a post-broadcast-grade time setting function and a function to start feeding after confirming that the arc is turned on.

On the other hand, in an embodiment of the present invention, in the case of separately supplying the filler metal in plasma welding or teag arc welding, if the filler material is temporarily supplied late or stopped, the state is detected to stop the welding power and stop the system, and an alarm is issued at the same time. It is possible to provide a supply stop device for detecting non-melting filler metal that makes a sound.

On the other hand, an embodiment of the present invention copies the NC data created by CAM in the robot welding process to the robot and calls the JOB number stored in the external device when changing the welding conditions according to the position in the welding preparation stage to easily change the welding conditions. is a system that The component may provide a robot welding condition data input system including CAM, NC data, a robot, a feeding device in which a plurality of welding condition JOBs are stored, and a welding power source.

On the other hand, an embodiment of the present invention is an apparatus and method for performing robot welding of a right-angle bent portion or a sharp bend portion while maintaining the direction of the entire broadcast level. The components of the device include a 6-axis vertical articulated welding robot, an additional 2-axis positioner, a filler metal supply device in which a plurality of welding condition JOBs are stored, a welding torch, a welding power source, and a bending robot welding device including a C-type filler metal supply device and a method therefor can provide

On the other hand, an embodiment of the present invention is a lamination method for improving wall resolution in thick-walled additive manufacturing, wherein the wall pass has a smaller weld cross-sectional area than the inner pass, thereby reducing instability against the flow of molten metal to improve wall resolution. A thick wall additive manufacturing method can be provided.

Although described above with reference to the embodiments of the present invention, the present invention is not limited thereto, and various modifications and applications are possible. That is, those skilled in the art will readily understand that many modifications are possible without departing from the gist of the present invention.

Claims (2)

As a robot welding device capable of welding a bent part that welds a right-angled bend or a sharp bend while maintaining the supply direction of supplying the filler metal from the front,
welding torch;
a welding power supply for applying a welding message to the welding torch;
6-axis vertical articulated welding robot equipped with a welding torch at the end;
a two-axis positioner for supporting a welding object to be welded by the welding robot; and
A robot welding device capable of welding bends with a filler metal feeding device that stores a number of JOBs and allows welding conditions to be changed only by changing the JOB call number when welding conditions are changed. As a control method of a robot welding device capable of welding a bent portion that welds a right-angled bend or a sharp bend while maintaining the supply direction of supplying the filler metal from the front,
The robot welding device,
welding torch;
a welding power supply for applying a welding message to the welding torch;
6-axis vertical articulated welding robot equipped with a welding torch at the end;
a two-axis positioner for supporting a welding object to be welded by the welding robot; and
It is equipped with a filler metal supply device that stores a number of JOBs and enables welding conditions to be changed only by changing the JOB call number when welding conditions are changed,
determining whether the current welding section is a right-angled bend or a sharp bend;
Calling a pre-stored right angle bending part JOB or abrupt bending part JOB when the current welding section is a right angle bending part or a sharp bending part; and
A control method of a robot welding apparatus capable of welding a bent portion comprising the step of controlling the welding to be performed by the right-angle bent portion JOB or the abruptly bent portion JOB.

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