Method for producing a joined body

Abstract

A method for producing an assembled body involves joining a first plate part (5A) and a second plate part (5B) by forming a penetration section (23A, 23B, 23C) that extends from the second plate part (5B) to the first plate part (5A) in an area where a weld bead (21) is formed. The weld bead (21) comprises a first weld section (21A), a second weld section (21B), and a third weld section (21C). The first weld section (21A) and the second weld section (21B) form a loop section (25). A terminal end of the third weld section (21C), forming a terminal end of the weld bead (21), is located on an inner circumferential side of the loop section (25).A quantity of heat (Q3) supplied to an area to be heated during the formation of the third weld section (21C) is controlled such that it is less than a quantity of heat (Q1) supplied to the area to be heated during the formation of the first weld section (21A).

Description

BACKGROUND The present disclosure relates to a method for producing an assembled body. For example, from the unexamined Japanese patent application with publication number 2024-139356, a technique is known to stack a first plate part and a second plate part on top of each other in their plate thickness directions and then weld them together, wherein a loop part is designed as a loop-shaped welding section and a terminal end of a weld bead is positioned within a closed area surrounded by the loop part. According to this technique, a gap between the first plate part and the second plate part is closed in the area where the loop part is formed. Therefore, for example, even if a fluid flow path is positioned on an outer circumferential side of the loop part and the fluid can enter the gap between the first and second plate parts, the fluid can be prevented from reaching an inner circumferential side of the loop part. Provided that the end of the weld bead is positioned on the inner circumferential side of the grinding part, as described above, even in cases where defects such as blowholes, cavities or cracks occur at the end of the weld bead, the fluid can be prevented from reaching the end of the weld bead, thus preventing fluid leakage. SUMMARY However, a thorough investigation by the present inventors revealed that, provided the end of the weld bead is positioned within the area surrounded by the grinding element, as described above, excessive penetration depth can occur near the end of the weld bead. If such a large penetration depth leads to scorching or burn-through of the back side, some products may not meet the quality requirements. According to one aspect of the present disclosure, it is desirable to provide a method for producing an assembled body that can prevent the occurrence of excessive penetration depth. (1) In one embodiment of the present disclosure, a method for producing an assembled body is provided. The method comprises: placing a first plate part and a second plate part, which are plate-shaped parts, such that the first plate part and the second plate part are stacked one above the other in their plate thickness directions; and then joining the first plate part and the second plate part by heating a region to be heated, located along a weld line, from one side of the second plate part of the first plate part and the second plate part that are stacked, thereby forming a weld bead extending from a starting end to a finishing end of the weld bead, while forming a penetrating section extending from the second plate part to the first plate part in a region where the weld bead is formed.The weld bead comprises a first weld section, a second weld section, and a third weld section, each forming a distinct part of the weld bead. The first and second weld sections are formed continuously such that a termination end of the first weld section coincides with a starting end of the second weld section, and a portion of the second weld section, differing from the starting end of the second weld section, is formed at a point that overlaps a portion of the first weld section, thus forming a loop section between the first and second weld sections.In the third welding section, the second and third welding sections are formed continuously such that the end of the second welding section coincides with the beginning of the third welding section, and the end of the third welding section, which is the end of the weld bead, is formed on an inner circumferential side of the workpiece. The process is controlled such that the amount of heat supplied to the area to be heated during the formation of the third welding section is less than the amount of heat supplied to the area to be heated during the formation of the first welding section. According to the method for manufacturing the assembled body, which is formed as described above, the first and second weld sections form the looped portion, and the final end of the third weld section, which is the end of the weld bead, is formed on the inner circumferential side of the looped portion. Furthermore, the process is controlled such that the amount of heat supplied to the area to be heated during the formation of the third weld section is less than the amount of heat supplied to the area to be heated during the formation of the first weld section. Therefore, the amount of heat supplied to the area to be heated during the formation of the third weld section is reduced compared to the amount supplied during the formation of the first weld section. This prevents excessive penetration depth compared to conventional techniques where no control is applied to increase or decrease the amount of heat supplied to the area. (2) In one embodiment of the present disclosure, the control can be carried out such that the amount of heat supplied to the area to be heated during the formation of the second weld section is less than the amount of heat supplied to the area to be heated during the formation of the first weld section and greater than the amount of heat supplied to the area to be heated during the formation of the third weld section. According to the method for producing the assembled body as described above, the amount of heat supplied to the area to be heated during the formation of the second weld section is reduced compared to the amount supplied during the formation of the first weld section. Furthermore, the amount of heat supplied to the area to be heated during the formation of the third weld section is reduced compared to the amount supplied during the formation of the second weld section. This prevents the occurrence of excessive penetration depth compared to a conventional technique where no control is implemented to increase or decrease the amount of heat supplied to the area. (3) In one embodiment of the present disclosure, the control can be carried out such that the amount of heat supplied to the area to be heated during the formation of the first weld section, the amount of heat supplied to the area to be heated during the formation of the second weld section and the amount of heat supplied to the area to be heated during the formation of the third weld section are gradually or continuously reduced. According to the method for manufacturing the joined body, which is formed as described above, the amount of heat supplied to the area to be heated during the formation of the first, second, and third weld sections is gradually or continuously reduced. This prevents the occurrence of excessive penetration depth compared to a conventional technique where no control is exercised to increase or decrease the amount of heat supplied to the area to be heated. (4) In one embodiment of the present disclosure, the control for reducing the quantities of heat may be a control for reducing the output power of a heat source. According to the process for manufacturing the assembled body as described above, the amount of heat supplied to the area to be heated is reduced by decreasing the output power of the heat source. Therefore, even in a case where, for example, the welding speed is kept constant, the amount of heat supplied to the area to be heated can be increased or decreased. (5) In one embodiment of the present disclosure, the control for reducing the amount of heat can be a control for increasing a welding speed. According to the process for manufacturing the assembled body, which is designed as described above, the amount of heat supplied to the area to be heated is reduced by increasing the welding speed. Therefore, even in a case where, for example, the output power of the heat source is kept at a constant level, the amount of heat supplied to the area to be heated can be increased or decreased. (6) In one embodiment of the present disclosure, the first weld section, the second weld section and the third weld section may include parts that extend parallel to each other, the third weld section being formed between the first weld section and the second weld section. BRIEF DESCRIPTION OF THE DRAWINGS An embodiment of the present disclosure is described below with reference to the accompanying drawings, in which: Fig. 1A shows a perspective exploded view of an assembled body; Fig. 1B shows a cross-sectional view of the assembled body showing a section plane perpendicular to the x-axis; Fig. 2A shows a bottom view of the assembled body; Fig. 2B shows an enlarged view of a second weld line near a termination end of the second weld line; Fig. 3A shows an explanatory view of the assembled body in a state in which a first weld section has been formed; Fig. 3B shows a cross-sectional view of the assembled body along a line IIIB-IIIB shown in Fig. 3A; Fig. 4A shows an explanatory view of the assembled body in a state in which a second weld section has been formed in addition to the first weld section; Fig.Fig. 4B is a cross-sectional view of the joined body along a line IVB-IVB shown in Fig. 4A; Fig. 5A is an explanatory view of the joined body in a state in which a third weld section has been formed in addition to the first weld section and the second weld section; Fig. 5B is a cross-sectional view of the joined body along a line VB-VB shown in Fig. 5A; and Fig. 6 is an enlarged view of a second weld line near a termination end of the second weld line, as exemplified in another embodiment. DETAILED DESCRIPTION OF EXAMPLES OF EXECUTION Next, a method for manufacturing a joined body is described with reference to an exemplary embodiment. [Formation of the joined body] As shown in Fig. 1A, an assembled body 1, which is illustrated by way of example in one embodiment of the present disclosure, is a heat exchanger for cooling a heat-generating body. The assembled body 1 is, for example, mounted in a vehicle (not shown) and serves to cool a traction battery mounted in the vehicle. The assembled body 1 has a first element 3A and a second element 3B. The component materials of the first element 3A and the second element 3B are not particularly restricted. In one example, the first element 3A and the second element 3B are made of a metallic material, such as iron, stainless steel, or aluminum, or a resin material, such as an engineering plastic, or other equivalent components.Either the metallic material or the resin material can be used, or both the metallic material and the resin material can be used together. For example, if the first element 3A is in contact with the heat-generating body, the first element 3A can be made of the metallic material, which has excellent thermal conductivity, and the second element 3B, which has recesses and protrusions, can be made of the resin material, which has excellent formability. The first element 3A comprises a first plate part 5A, which is a plate-shaped component. The second element 3B comprises a second plate part 5B, which is also a plate-shaped component. As shown in Fig. 1B, the first plate part 5A and the second plate part 5B of the first element 3A and the second element 3B are stacked on top of each other in their respective thickness directions and are laser-welded together from one side of the second plate part 5B, forming a welded joint in the form of an overlap joint. A specific welding process will be described in detail later. The first element 3A includes an inlet channel 7A and an outlet channel 7B. The inlet channel 7A and the outlet channel 7B are tubular parts that project from the first element 3A. Through-holes with diameters equal to those of the inlet channel 7A and the outlet channel 7B are formed in the first element 3A. The inlet channel 7A and the outlet channel 7B project beyond the circumferences of the through-holes. The second element 3B includes a recess 8. The recess 8 can be formed only in the first element 3A or it can be formed in both the first element 3A and the second element 3B. That is, it is not restricted in which of the first element 3A and the second element 3B the recess 8 is formed. The present embodiment is described below by way of example for a case in which the recess 8 is formed in the second element 3B. The recess 8 is a part of the second element 3B that is recessed in a negative z-axis direction, as shown in Fig. 1A. The recess 8 is U-shaped when viewed in the negative z-axis direction. In particular, the recess 8 includes a first groove 8A, a second groove 8B, and a third groove 8C. The first groove 8A is a section extending linearly along the x-axis. The second groove 8B is a section extending continuously from the first groove 8A. The second groove 8B is a section curved around the z-axis as its center of curvature, with a central angle of curvature of 180 degrees, i.e., a semicircular arc segment. The third groove 8C is a section extending continuously from the second groove 8B and extending linearly along the x-axis parallel to the first groove 8A. The second plate segment 5B is a different part of the second element 3B than the recess 8. As shown in Fig. 1B, the stacking of the first plate 5A and the second plate 5B along their thickness directions creates a U-shaped flow path 9 enclosed by the first element 3A and the recess 8, through which a refrigerant flows. The refrigerant flows from a pipe serving as a supply path into the flow path 9 via the inlet channel 7A and from the flow path 9 out via the outlet channel 7B to a pipe serving as a discharge path. The refrigerant flowing through the flow path 9 cools the heat-generating body in contact with the first element 3A. It should be noted that the refrigerant can be in the form of a liquid or a gas. [Explanation of the welding process] Next, a welding process for the joined body 1 is described. The first element 3A and the second element 3B are welded together at the first plate part 5A and the second plate part 5B. Fig. 2A shows a first weld line 11 and a second weld line 12, which represent weld sections of the first element 3A and the second element 3B. The first weld line 11 extends from a starting end 11A, forms a loop in an area surrounding the recess 8, and then reaches a finishing end 11B. The first weld line 11 intersects itself at an intersection point 13A. The first weld line 11 is a line that can be drawn in a single continuous stroke from the starting end 11A to the finishing end 11B. The second weld line 12 extends from a start end 12A located on an outer circumferential side of the first weld line 11, intersects the first weld line 11 at an intersection point 13B, and then extends to an area on an inner circumferential side of the first weld line 11. A portion of the second weld line 12, extending linearly along the x-axis from the start end 12A, passes between the first groove 8A and the third groove 8C of the recess 8, and then the second weld line 12 reaches a termination end 12B located near the second groove 8B of the recess 8. The second weld line 12 is a line that can be drawn in a single continuous stroke from the start end 12A to the termination end 12B. Fig. 2B shows an enlarged view of the shape of the second weld line 12 near the end 12B. The second weld line 12 extends linearly in a positive x-axis direction from the starting end 12A, curves around the z-axis as its center of curvature, and then reaches a point where the central angle of the curvature is 180 degrees. This point is referred to as "limit point 15A". The second weld line 12 extends linearly in a negative x-axis direction from limit point 15A, curves around the z-axis as its center of curvature, and then reaches a point where the central angle of the curvature is 180 degrees. This point is referred to as "limit point 15B". The second weld line 12 extends linearly in a positive x-axis direction from limit point 15B and reaches the end 12B. Laser welding is performed along the first weld line 11 and the second weld line 12, as described above, from the side of the second plate part 5B. The first weld line 11 is located in the area surrounding an outer circumference of the recess 8 forming the flow path 9 (see Fig. 1B) and intersects itself at intersection point 13A, thus forming a closed loop. Accordingly, by performing laser welding on an area extending along the first weld line 11 as a region to be heated, the flow path 9 can be restricted to an inner circumferential side of the weld section formed in a closed loop.Therefore, even in a case where a fluid introduced into the flow path 9 enters the gap between the first plate 5A and the second plate 5B, the fluid does not escape to an outer circumferential side of the weld section extending along the first weld line 11. Furthermore, the start end 11A and the finish end 11B of the first weld line 11 are located on the outer circumferential side of the weld section, which is formed in a closed loop shape. Therefore, even if the fluid introduced into the flow path 9 enters the gap between the first plate 5A and the second plate 5B, it does not reach the weld section near the start end 11A or the weld section near the finish end 11B. Defects such as blowholes, cavities, and cracks are likely to occur in the weld section near the start end 11A or the weld section near the finish end 11B during welding. Since the fluid does not reach such areas where defects are likely to occur, as described above, the fluid sealing performance of the joined body 1 can be improved. By performing laser welding on an area extending along the second weld line 12 as a region to be heated, the gap between the first plate part 5A and the second plate part 5B can be closed in an area between the first groove 8A and the third groove 8C of the recess 8. Therefore, a short circuit between the first groove 8A and the third groove 8C across the gap between the first plate part 5A and the second plate part 5B can be prevented, and thus the intended cooling performance of the flow path 9 with a U-shape can be achieved. The start end 12A of the second weld line 12 is located on the outer circumferential side of the weld section, which is formed in a closed loop along the first weld line 11. Therefore, even if the fluid introduced into the flow path 9 enters the gap between the first plate 5A and the second plate 5B, it does not reach the weld section near the start end 12A. Defects such as blowholes, cavities, and cracks are likely to occur in the weld section near the start end 12A during welding. Since the fluid does not reach such areas where defects are likely to occur, as described above, the fluid sealing performance of the joined body 1 can be improved. At the second weld line 12 near the end 12B, welding is carried out along the second weld line 12, as shown in enlarged scale in Fig. 2B. At this point, a control is implemented to adjust the amount of heat supplied to the area to be heated. Specifically, in a first section 17A extending to the end point 15A, an amount of heat Q1 is supplied to the area to be heated. Then, in a second section 17B extending from the end point 15A to the end point 15B, an amount of heat Q2 is supplied to the area to be heated. Then, in a third section 17C extending from the end point 15B to the end 12B, an amount of heat Q3 is supplied to the area to be heated. The heat quantities Q1, Q2, and Q3 satisfy the relationship Q1 ≥ Q2 > Q3, and the heat quantities supplied to the area to be heated are gradually reduced. Specific values ​​of the heat quantities Q1, Q2, and Q3 can be adjusted as needed. For example, if the heat quantity Q1 is a standard heat quantity for welding, the heat quantity Q2 could be approximately 80% of the heat quantity Q1, and the heat quantity Q3 could be approximately 40% of the heat quantity Q1. Any method can be used to gradually reduce the heat quantities Q1, Q2, and Q3. For example, the heat quantities Q1, Q2, and Q3 can be gradually reduced by adjusting the output power of a heat source. With a constant output power of the heat source, the amount of heat supplied to a region of a certain length to be heated decreases as the welding speed increases. Therefore, the heat quantities Q1, Q2, and Q3 can be gradually reduced by increasing the welding speed while maintaining a constant output power of the heat source. The example above describes the gradual, stepwise reduction of the heat quantities Q1, Q2, and Q3. The heat quantity can be reduced in a larger number of steps, or it can be reduced continuously and gradually. Furthermore, as explicitly indicated by the inequality above, the heat quantities Q1 and Q2 can be equal, and the heat quantities Q2 and Q3 can be reduced stepwise or continuously. During welding in the first section 17A, a weld bead 21 is formed in an area extending along the first section 17A, as shown in Fig. 3A and Fig. 3B. Hereinafter, the weld bead 21 formed in the area extending along the first section 17A is also referred to as a "first weld section 21A". In an area where the first weld section 21A is formed, a penetrating section 23A is formed, which penetrates the second plate part 5B up to the first plate part 5A, as shown in Fig. 3B. When welding is performed in the second section 17B after the first section 17A, the weld bead 21 is formed in an area extending along the second section 17B, as shown in Figs. 4A and 4B. Hereinafter, the weld bead 21 formed in the area extending along the second section 17B is also referred to as a "second weld section 21B". In an area where the second weld section 21B is formed, a penetrating section 23B is formed, which penetrates the second plate part 5B to the first plate part 5A, as shown in Fig. 4B. Welding in the second section 17B is performed immediately after welding in the first section 17A. Therefore, the temperature of the area to be heated has already risen to a certain degree when welding is performed in the second section 17B. In the present embodiment, however, the amount of heat Q2 is supplied to the area to be heated during welding in the second section 17B, as described above. Accordingly, the amount of heat supplied to the area to be heated during welding in the second section 17B is reduced compared to the amount of heat supplied to the area to be heated during welding in the first section 17A. This prevents the formation of the penetrating section 23B with excessive depth. Therefore, compared to a case where welding continues without changing the heat quantities, burn-through or back-scorching on one side of a first plate 5A of the joined body 1 can be prevented, and consequently, adequate flatness of the side of the first plate 5A of the joined body 1 can be maintained. A termination end of the first weld section 21A and a starting end of the second weld section 21B, located at a point coinciding with boundary point 15A, are formed such that they overlap at this point. A termination end of the second weld section 21B is located at a point different from the point where the starting end of the second weld section 21B is located. Also near the termination end of the second weld section 21B, a portion of the second weld section 21B is formed at a point that overlaps a portion of the first weld section 21A. Consequently, the first weld section 21A and the second weld section 21B form a loop portion 25, which is a loop-shaped weld section. In the second weld line 12, the second section 17B does not reach a point that overlaps the first section 17A. However, since the weld bead 21 has a certain width, the second weld section 21B does reach a point that overlaps the first weld section 21A. As a result, the loop portion 25 forms a closed loop. In other words, the loop portion 25 forms a loop without any openings along its circumference. In the present embodiment, since the weld bead 21 has a certain width, an area on the inner circumferential side of the loop part 25 is filled by the loop part 25 without a gap. However, a shape without such gaps formed on the inner circumferential side is also contained in the "loop part" as mentioned herein. In other words, the "loop part," as mentioned herein, has nothing to do with whether or not a gap exists on the inner circumferential side of the loop part. When welding is performed in the third section 17C after the second section 17B, a weld bead 21 is formed in an area extending along the third section 17C, as shown in Fig. 5A and Fig. 5B. Hereinafter, the weld bead 21 formed in the area extending along the third section 17C is also referred to as the "third weld section 21C". In an area where the third weld section 21C is formed, a penetrating section 23C is formed, as shown in Fig. 5B. Welding in the third section 17C is performed immediately after welding in the second section 17B. Therefore, the temperature of the area to be heated has already risen to a certain degree when welding is performed in the third section 17C. Furthermore, the third weld section 21C is formed at a point that overlaps the first weld section 21A and the second weld section 21B. In the present embodiment, however, the quantity of heat Q3 is supplied to the area to be heated during welding in the third section 17C, as described above. Accordingly, the amount of heat supplied to the area to be heated during welding in the third section 17C is reduced compared to the amount of heat supplied to the area to be heated during welding in the second section 17B. This prevents the formation of the penetrating section 23C with excessive depth. Therefore, compared to a case where welding continues without changing the heat quantities, burn-through or back-scorching on one side of the first plate 5A of the joined body 1 can be prevented, and consequently, adequate flatness of the side of the first plate 5A of the joined body 1 can be maintained. In the area where the loop section 25 is formed, the gap between the first plate section 5A and the second plate section 5B is closed in a loop shape. Therefore, even if the fluid introduced into the flow path 9 enters the gap between the first plate 5A and the second plate 5B, it does not reach the area surrounded by the loop section 25. A termination end of the third weld section 21C, which is the termination end of the weld bead 21, is formed at a location on the inner circumferential side of the looped part 25. Therefore, even if the fluid introduced into the flow path 9 enters the gap between the first plate 5A and the second plate 5B, it does not reach the weld section near the termination end 12B. Defects such as blowholes, cavities, and cracks are likely to occur in the weld section near the termination end 12B during welding. Since the fluid does not reach the area where such defects are likely to occur, the fluid sealing performance of the joined body 1 can be improved. [Effects] As described above, according to the method for producing the assembled body 1, the first weld section 21A and the second weld section 21B form the loop section 25, and the terminal end of the third weld section 21C, which is the terminal end of the weld bead 21, is formed at the location on the inner circumferential side of the loop section 25. Furthermore, the control is carried out such that the amount of heat Q3 supplied to the area to be heated during the formation of the third weld section 21C is less than the amount of heat Q1 supplied to the area to be heated during the formation of the first weld section 21A. Accordingly, the amount of heat supplied to the area to be heated during the formation of the third weld section 21C is reduced compared to that supplied during the formation of the first weld section 21A. In contrast to a conventional technique where no control is implemented to increase or decrease the amount of heat supplied to the area to be heated, the occurrence of excessive penetration depth can therefore be prevented. Furthermore, in the present embodiment, the amount of heat supplied to the area to be heated during the formation of the second weld section 21B is reduced compared to the amount supplied during the formation of the first weld section 21A. Additionally, the amount of heat supplied to the area to be heated during the formation of the third weld section 21C is reduced compared to the amount supplied during the formation of the second weld section 21B. Therefore, in contrast to a conventional technique where no control is implemented to increase or decrease the amount of heat supplied to the area to be heated, the occurrence of excessive penetration depth can be prevented. [Other embodiments] Although the method for manufacturing the assembled body was described with reference to the exemplary embodiment, this embodiment is merely an example of one configuration of the present disclosure. Accordingly, the present disclosure is not limited to the exemplary embodiment described above and can be implemented in various forms within the scope of protection of the technical concept of the disclosure. In the embodiment described above, the specific shape of the second weld line 12 near the termination end 12B is described as an example. However, the shape of the second weld line 12 near the termination end 12B is not limited to the example described above. In another specific example, such as a second weld line 32 shown in Fig. 6, a first section 37A and a second section 37B can intersect at an intersection point 33A to form a loop portion 45. In this case as well, a termination end 32B of a second weld line 32, which is a termination end of a third section 37C, can be positioned on an inner circumferential side of the loop portion 45. It should be noted that the “loop portion 45,” as mentioned here, is a section in which a weld section is formed, corresponding to the loop portion 25 in the embodiment described above. Even in a case where a weld bead is formed along the second weld line 32, as described above, excessive penetration depth can be prevented by gradually or continuously reducing the amounts of heat supplied to the first section 37A, the second section 37B and the third section 37C in that order. It should be noted that in the example shown in Fig. 6, the first section 37A and the second section 37B intersect at intersection point 33A. If the penetration depth at intersection point 33A is excessive, a boundary point 35B can be positioned between the second section 37B and the third section 37C, between intersection point 33A and a boundary point 35A between the first section 37A and the second section 37B along the second weld line 32. This allows the first section 37A and the third section 37C to intersect at intersection point 33A. If the penetration depth at intersection point 33B is excessive, the amount of heat applied at a location near intersection point 33B can be further reduced. In the embodiment described above, the heat exchanger for cooling the heat-generating body is described as a specific example of the assembled body 1. The method for manufacturing the assembled body of the present disclosure can also be used in the manufacture of products other than the heat exchanger.

[0055] Two or more functions that are performed by one element in the embodiments described above can be achieved by two or more elements. One function that is performed by one element in the embodiments described above can be achieved by two or more elements. Two or more functions that are performed by two or more elements in the embodiments described above can be achieved by one element.A function that is performed by two or more elements in the embodiments described above can be achieved by a single element. Furthermore, some of the configurations in the embodiments described above can be omitted, and at least some of the configurations in the embodiments described above can be added to or replaced by another part of the configurations in the embodiments described above.

[0056] [Technical ideas revealed here] [Point 1] A method for producing an assembled body, the method comprising: placing a first plate part and a second plate part, the latter being plate-shaped parts, such that the first plate part and the second plate part are stacked one above the other in their plate thickness directions; and then joining the first plate part and the second plate part by heating a region to be heated, located along a weld line, from one side of the second plate part of the first plate part and the second plate part that are stacked, thereby forming a weld bead extending from a starting end to a finishing end of the weld bead, while forming a penetrating section extending from the second plate part to the first plate part in a region where the weld bead is formed, the weld bead comprising a first weld section,comprising a second weld section and a third weld section, each forming a respective part of the weld bead, wherein the first weld section and the second weld section are continuously formed such that a termination end of the first weld section coincides with a starting end of the second weld section, and a part of the second weld section, which differs from the starting end of the second weld section, is formed at a point that overlaps a part of the first weld section, whereby the first weld section and the second weld section form a loop part, which is a loop-shaped weld section, wherein in the third weld section the second weld section and the third weld section are continuously formed such thatthat a termination end of the second weld section coincides with a commencing end of the third weld section, and a termination end of the third weld section, which is the termination end of the weld bead, is formed on an inner circumferential side of the looped part, the method further comprising carrying out a control to reduce quantities of heat such that the quantity of heat supplied to the area to be heated during the formation of the third weld section is less than the quantity of heat supplied to the area to be heated during the formation of the first weld section.

[0057] [Point 2] The method for producing the joined body according to point 1, wherein the control for reducing the quantities of heat is carried out such that the quantity of heat supplied to the area to be heated during the formation of the second weld section is less than the quantity of heat supplied to the area to be heated during the formation of the first weld section, and greater than the quantity of heat supplied to the area to be heated during the formation of the third weld section.

[0058] [Point 3] The method for producing the joined body according to point 2, wherein the control for reducing the quantities of heat is carried out in such a way that the quantity of heat supplied to the area to be heated during the formation of the first weld section, the quantity of heat supplied to the area to be heated during the formation of the second weld section, and the quantity of heat supplied to the area to be heated during the formation of the third weld section are gradually or continuously reduced.

[0059] [Point 4] The method for producing the assembled body according to one of points 1 to 3, wherein the control for reducing the heat quantities is a control for reducing an output power of a heat source.

[0060] [Point 5] The method for producing the joined body according to one of points 1 to 4, wherein the control for reducing the amount of heat is a control for increasing a welding speed.

[0061] [Point 6] The method for producing the joined body according to one of points 1 to 5, wherein the first welding section, the second welding section and the third welding section include parts that extend parallel to each other, the third welding section being formed between the first welding section and the second welding section. QUOTES INCLUDED IN THE DESCRIPTION This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature JP 2024-139356

[0002]

Claims

Method for producing an assembled body (1), the method comprising: placing a first plate part (5A) and a second plate part (5B), which are plate-shaped parts, such that the first plate part (5A) and the second plate part (5B) are stacked one above the other in their plate thickness directions; and then joining the first plate part (5A) and the second plate part (5B) by heating a region to be heated, which is located along a weld line, from one side of the second plate part (5B), of the first plate part (5A) and the second plate part (5B) which are stacked, thereby forming a weld bead (21) extending from a starting end to a finishing end of the weld bead (21), while forming a penetrating section (23A, 23B, 23C) which is located in a region where the weld bead (21) is formed,from the second plate part (5B) to the first plate part (5A), wherein the weld bead (21) includes a first weld section (21A), a second weld section (21B) and a third weld section (21C), each forming a respective section of the weld bead (21), wherein the first weld section (21A) and the second weld section (21B) are formed continuously such that a termination end of the first weld section (21A) coincides with a starting end of the second weld section (21B), and a portion of the second weld section (21B) that differs from the starting end of the second weld section (21B) is formed at a location that overlaps a portion of the first weld section (21A), whereby the first weld section (21A) and the second weld section (21B) form a loop section (25), which is a loop-shaped weld section.and wherein in the third welding section (21C) the second welding section (21B) and the third welding section (21C) are continuously formed such that a termination end of the second welding section (21B) coincides with a starting end of the third welding section (21C) and a termination end of the third welding section (21C), which is the termination end of the weld bead (21), is formed on an inner circumferential side of the loop part (25), wherein the method further comprises carrying out a control to reduce quantities of heat such that a quantity of heat (Q3) supplied to the area to be heated during the formation of the third welding section (21C) is less than a quantity of heat (Q1) supplied to the area to be heated during the formation of the first welding section (21A). Method for producing the joined body (1) according to claim 1, wherein the control for reducing the amounts of heat is carried out such that an amount of heat (Q2) supplied to the area to be heated during the formation of the second weld section (21B) is less than the amount of heat (Q1) supplied to the area to be heated during the formation of the first weld section (21A), and is greater than the amount of heat (Q3) supplied to the area to be heated during the formation of the third weld section (21C). Method for producing the joined body (1) according to claim 2, wherein the control for reducing the amounts of heat is carried out such that the amount of heat (Q1) supplied to the area to be heated during the formation of the first weld section (21A), the amount of heat (Q2) supplied to the area to be heated during the formation of the second weld section (21B), and the amount of heat (Q3) supplied to the area to be heated during the formation of the third weld section (21C) are gradually or continuously reduced. Method for producing the assembled body (1) according to one of claims 1 to 3, wherein the control for reducing the heat quantities is a control for reducing an output power of a heat source. Method for producing the joined body (1) according to one of claims 1 to 4, wherein the control for reducing the amount of heat is a control for increasing a welding speed. Method for producing the joined body (1) according to any one of claims 1 to 5, wherein the first weld section (21A), the second weld section (21B) and the third weld section (21C) comprise sections that extend parallel to each other, wherein the third weld section (21C) is formed between the first weld section (21A) and the second weld section (21B).

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