Assembly of components interconnected by means of a beam-welding method, and corresponding production method

Abstract

The invention relates to an assembly (100) comprising two components (101, 102) which are interconnected by means of a beam-welding method so that a connecting seam (110) is formed between the components (101, 102). The connecting seam (110) has an end portion (113) with an end (114), and a portion (117), the portion (117) and the end portion (113) intersecting at an intersection point (118), and the connecting seam (110) being tight in a region of the end portion (113) which extends from the intersection point (118) in a direction away from the end (114). The invention also relates to a corresponding method for producing an assembly (100) of this type.

Description

[0001] DESCRIPTION

[0002] DESIGNATION

[0003] Arrangement of components joined together by means of a beam welding process and corresponding manufacturing process

[0004] TECHNICAL AREA

[0005] The present disclosure relates to arrangements of components that are tightly joined to one another by means of beam welding processes, such as laser welding or electron beam welding, as well as corresponding manufacturing processes. For example, such an arrangement can consist of a housing and one or more associated housing covers, which together enclose a media-tight welded interior.

[0006] BACKGROUND OF THE INVENTION

[0007] In technical applications in motor vehicles, housing covers and housings are typically screwed, crimped, or bonded together to create a leak-proof seal. Alternatively, the covers can also be welded to the housings. A common method for joining, for example, die-cast aluminum housings and stamped aluminum covers is friction stir welding.

[0008] Concepts with tightly screwed, crimped, or glued lids on the housing involve more individual parts and a greater number of process steps compared to welded solutions. This results in comparatively higher costs due to the bill of materials, process times, and equipment used. These solutions also typically require more installation space.

[0009] Friction stir welding, on the other hand, requires long process times. The process generates high heat input and, above all, high forces, both of which can lead to part distortion, among other things. Mechanical post-processing of the parts in the weld area is therefore unavoidable. The entire process also typically produces contamination particles.

[0010] SUMMARY AND FORMS OF EXECUTION

[0011] It is therefore an objective of the present disclosure to provide an arrangement and a corresponding manufacturing process for interconnected components, for example, a housing cover connected to a housing body or various housing components, such as cooling components. The arrangement and process should be simple and cost-effective to implement and, at the same time, ensure a durable, robust, and leak-proof connection between the components.

[0012] According to a first aspect, an arrangement is provided which comprises two components joined by a beam welding process, forming a weld seam between the components. The weld seam has an end section and a segment, wherein the segment and the end section intersect or overlap at a point of intersection. In a region of the end section extending from the point of intersection in a direction away from the end, the weld seam is tight, in particular media-tight.

[0013] According to a further aspect, a method for joining two components is provided. The method comprises the following steps: forming a weld seam between the components by means of laser welding. The weld seam has an end section and a segment, wherein the segment and the end section intersect or overlap at a point of intersection. In a region of the end segment extending from the point of intersection in a direction away from the end, the weld seam is tight, in particular media-tight. In the context of this disclosure, beam welding is defined, for example, as a joining or bonding method for permanently fusing or connecting components, in which the energy supply is beam-like, for example via a laser or an electron beam.In laser welding, a laser beam and the components move relative to each other, creating a weld seam or joint that fuses the components together. The use of lasers can be characterized by short processing times, a small number of process steps, and a wide variety of designs, for example, compared to technologies such as friction stir welding or bolted and bonded connections.

[0014] In the context of this disclosure, a joining seam is defined, for example, as a weld seam by means of which the two components are joined. The joining seam may consist of one or more individual welds, each individual weld having exactly one weld start and exactly one weld end. At the weld start, a region of the weld seam typically forms with a weld reinforcement or a material rise, particularly in comparison to the further course of the weld seam. At the weld end, a region of the weld seam typically forms with a material sink or an end crater, particularly in comparison to the preceding course of the weld seam.

[0015] In the context of this disclosure, a tightly formed weld is defined, for example, as a weld that prevents certain substances from penetrating from one side of the weld to the other, particularly to an extent greater than a predetermined, possibly substance-specific, tightness threshold. A tightly formed weld can, for example, be tight to certain or all gases, tight to certain or all liquids, and / or tight to fluids. If the weld is media-tight, no substances whatsoever can penetrate from one side of the weld to the other. According to one embodiment, a weld is tight if and when it is airtight up to a predetermined air pressure limit, for example, 2 bar, and / or withstands a burst pressure up to a predetermined burst pressure limit, for example, 25 bar.Such values ​​were achieved in experiments.

[0016] A more realistic stress test is the pressure pulse test. Here, pressure cycles are applied at a defined frequency and at a specific temperature, e.g., the maximum operating temperature. This test can be performed either until failure occurs or until a certain number of cycles are reached without failure. It can be very useful to characterize the robustness of parts at more than one pressure level. In trials, values ​​for the pressure pulse alternating test with < 70k cycles were achieved.

[0017] In the context of the present disclosure, an intersection point is defined, for example, as a point or region where two sections of the weld intersect or overlap. The two sections may form any angles with each other. At least one of the sections extends on both sides of the intersection point. One of the sections, and thus the weld, may begin or end at the intersection point, in particular precisely at the intersection point. Both sections may extend on either side of the intersection point.

[0018] The described arrangement and the corresponding manufacturing process can be advantageous for creating a robust, space-saving, and pressure-tight beam weld connection in a particularly simple and cost-effective manner, for example, between an aluminum die-cast housing part and one or more other stamped aluminum housing parts. Possible applications include inverters, high-voltage boxes, DC-DC converters, and other power electronics assemblies, or cooling assemblies.

[0019] Beam welding systems, such as laser welding systems, can be flexibly used for a wide variety of contours in different products, resulting in relatively low investment costs. In the past, laser welding of die-cast materials, for example, was not recommended or carried out with conventional systems. Among other things, it had been found that a completely leak-proof weld seam could not be produced. In conventional laser welding processes, such as butt welding or fillet welding, the beginning and end of the weld are usually aligned along the same line. However, this strategy led to leaks in lap welding. One possible reason for this is that material displacement can occur during laser welding, especially lap welding. A material buildup occurs behind the laser beam.At the end of the weld, however, the weld dips and forms a valley. Therefore, stress cracks are often visible in the area of ​​the weld end, which can cause leaks.

[0020] By having a section and an end section of the weld intersect at a single point, the weld start and end can be positioned outside the geometry to be sealed. This reduces or even eliminates the previously described risk of leaks. As a result, laser welding can advantageously create a weld that seals a defined area. For example, a sealed chamber can be created by joining a lid to a housing. Previous problems associated with laser welding, particularly overlap welding, can be mitigated or completely eliminated.

[0021] This method and arrangement can be advantageous because a weld develops transverse stresses along its welding direction, i.e., at 90° to the feed direction. These stresses, caused by shrinkage, are tensile stresses in the weld perpendicular to the feed direction. These shrinkage-induced tensile stresses can lead to longitudinal cracks in the weld and thus to leaks. However, if a weld is placed with its start and end on the same line, for example, when welding aluminum, these transverse stresses from both superimposed welds, the longitudinal stresses from the start and end, and the stresses of the end crater (shrinkage) all add up. Therefore, this area is critical and frequently prone to cracking, as the end crater thus combines metallurgical and mechanical stress concentration effects.

[0022] Cracks in an area to be sealed can be avoided if the critical start and end areas of the weld are moved out of the functional area of ​​the sealing weld and are designed in such a way that the otherwise adding stresses in the critical area of ​​the overlap are minimized by crossing the welds.

[0023] For the aforementioned reasons, according to one embodiment, the stress situation at the weld initiation and, in particular, at the weld end, including the metallurgical and mechanical notch, should be positioned away from the area of ​​influence of the stresses at the intersection. Furthermore, the stresses between the weld initiation and the weld end should also not interact, and the weld initiation and weld end should be positioned outside the functional area, i.e., outside the sealing weld area. Therefore, it is recommended that, according to one embodiment, the cover plate and the cast base body be provided with a "run-off area" in the sense of a classic run-off plate.

[0024] According to one embodiment, the end is a weld start or a weld end, that is, a position where a joining seam, in particular a single seam, begins or ends.

[0025] According to one embodiment, the beam welding process comprises at least one of the following processes: laser welding, electron beam welding, or plasma welding. In the context of the disclosure, plasma welding is classified as a beam welding process due to the resulting plasma jet, even though the term is often defined differently in the technical literature.

[0026] According to one embodiment, the seam encloses a sealing area formed by a surface of one of the two components, wherein the end, in particular all ends of the seam and / or of individual seams of the seam, are arranged outside the sealing area. The portion of the seam enclosing the sealing area can be tightly formed. The surface can be a continuous surface, which in particular has no holes. The end(s) can be arranged at an edge of the surface or of the component. Such an embodiment can be advantageous for sealing a chamber adjacent to the sealing area, especially if the ends of the seam are potential sources of leakage.

[0027] According to one embodiment, the first of the two components forms a housing, and the second forms a housing cover. The housing can be, for example, an electronics housing, a motor housing, or a cooling duct. Such an embodiment can be advantageous because the method ensures the tightness of a housing joined by beam welding. As already explained, beam welding, especially laser welding, offers significant advantages over comparable methods.

[0028] According to one embodiment, the housing and the housing cover form at least one sealed chamber, in particular two or more sealed chambers. The chamber or chambers can be media-tight. The two or more chambers can also be sealed from each other.

[0029] According to one embodiment, one of the components, in particular the housing cover, forms a discharge area outside a sealing area formed by a surface of the component and enclosed by the connecting seam. The end, in particular all ends, is located in this discharge area. The discharge area can be a protruding edge and / or an area with a relief hole.

[0030] According to one embodiment, one of the components, in particular the housing cover, forms a discharge area outside the one or more chambers, in which the end, in particular all ends, are arranged. The discharge area can be a projecting edge of the component and / or an area of ​​the component with a relief hole. The discharge area can, for example, be a discharge plate. The width of the discharge area can be designed such that stresses are reduced.

[0031] A modified design may be necessary to reliably seal the chambers.

[0032] According to one embodiment, the outlet area widens near the intersection point and / or has a relief hole, in particular a relief bore, near the intersection point. Such an embodiment can be advantageous for a space-saving, tight connection of components using a beam welding process. The edge is therefore only widened where necessary for the arrangement of the ends.

[0033] According to one embodiment, the components to be welded, in particular the housing and / or the housing cover, are made of aluminum, or in particular consist of aluminum. The housing can, for example, be an aluminum die-cast housing. The housing cover can, for example, be a stamped part, a stamped and bent part, a forged part, or a cast part, each made of aluminum. Several housing parts or several covers can also be welded together. Such an embodiment can be advantageous because, in the past, leaks typically occurred when beam welding, especially laser welding, such materials. There was at least a partial misconception that a tight joint of such materials could not be achieved by beam welding.

[0034] According to one embodiment, the section is a further end section with a further end, wherein the weld seam is tightly formed, in particular media-tight, in a region of the further end section that extends from the intersection point in a direction away from the further end. The further end can be a weld start or a weld end, that is, a position where a weld seam begins or ends. According to one embodiment, the further end, in particular all ends of the weld seam, are arranged outside a sealing area formed by a surface of one of the two components, which the weld seam encloses. According to one embodiment, the further end, in particular all ends of the weld seam, are arranged in a projecting edge of a cover.

[0035] According to one embodiment, the section is a segment of a closed path that forms part of the weld seam, wherein the weld seam is sealed over the entire closed path. In this case, the section is not an end segment. Such an embodiment can be advantageous because one or more sealed chambers can be formed by means of the closed path.

[0036] According to one embodiment, a region of the end section between the intersection point and the end is longer than a weld indentation or area of ​​a weld indentation at a weld end of the joint and / or longer than a weld reinforcement or area of ​​a weld reinforcement at a weld start of the joint. This can apply to all intersection points of the joint. The weld indentation can denote a concave shape of the weld, in particular an end crater, and the weld reinforcement can denote a convex shape of the weld. Weld reinforcement and weld indentation can be defined, in particular, in comparison to the further course of the weld. The joint can have one or more weld starts and / or one or more weld ends. The weld reinforcement and / or the weld indentation can be caused by a material displacement during beam welding, in particular laser welding.Such an embodiment can be advantageous because seam sinking and / or seam reinforcement can be causes of leaks, for example due to tensile stresses.

[0037] According to one embodiment, a region of the end section between the intersection point and the end, and / or a region of the further end section between the intersection point and the further end, is long enough that stresses from a weld start or weld end at the end or at the further end do not interact with stresses at the intersection point. This can apply to all intersection points of the weld. For example, an end crater of the weld can be located in the region of the end section or the region of the further end section, particularly outside a sealing chamber to be closed by the welds. The end crater can be positioned at least far enough away from the intersection point that shrinkage stresses of the end crater, and thus potential cracking, do not interact with shrinkage stresses of the intersection point.Such an embodiment can be advantageous in order to position any potential leaks at the ends of the joint seam outside of an area to be sealed.

[0038] According to one embodiment, all angles between the end section and the section at the intersection point are greater than 70 degrees and less than 110 degrees, in particular greater than 80 degrees and less than 100 degrees, in particular greater than 85 degrees and less than 95 degrees, and in particular exactly 90 degrees. Such an embodiment can be advantageous because it allows the area of ​​overlap at the intersection point to be kept as small as possible, i.e., as localized as possible. This can be advantageous with regard to material displacement and shrinkage stresses during beam welding. For example, at an approximately right angle, the tensile stresses of the two sections can largely cancel each other out.

[0039] According to one embodiment, the connecting seam consists of at least two individual welds, each individual weld having exactly two end sections. The at least two individual welds can form at least one further intersection point, which can have similar properties to the intersection point described above. Such an embodiment can be advantageous for forming complex geometries, for example, two or more chambers. According to one embodiment, an individual weld connects a partition wall between two chambers to a cover. Alternatively, the connecting seam can consist of only a single individual weld, which, for example, forms a circumferential weld seam.

[0040] According to one embodiment, the two components overlap at the joint, with the joint extending through one component into the other. Such a joint can be achieved, for example, by overlap welding. In the context of the present disclosure, overlap welding is defined, for example, as welding overlapping components, in which, in particular, the weld seam extends through a first of the two components into the second component. With regard to a welding device, in particular a laser, an electron beam, or a plasma welding device, the second component can be arranged on a side opposite the first component.

[0041] Such an embodiment can be advantageous because, generally, the use of lap welding allows for larger tolerances in the parts' geometry regarding the outer contour than, for example, butt or fillet welding. This reduces tooling and part costs. Furthermore, significantly smaller radii can be achieved with lap welding than with friction stir welding. Mechanical pre-machining or pretreatment may also be unnecessary.

[0042] According to one embodiment, no adhesive and / or additional fastening means, such as a screw, nail, rivet or bolt, is used to join the two components.

[0043] BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Further advantages and beneficial designs and further developments of the method, the control unit and the computer program result from the following exemplary embodiments shown in connection with the figures.

[0045] They show:

[0046] Figure 1 shows an exemplary arrangement with a connecting seam between components;

[0047] Figure 2 shows an arrangement with a connecting seam between components according to an embodiment of the present disclosure; Figures 3 and 4 show different welding methods for producing a connecting seam according to embodiments of the present disclosure; Figures 5 to 9 show different intersection points of a section with an end section as part of a connecting seam for an arrangement according to embodiments of the present disclosure.

[0048] Identical, similar, or similarly effective elements are marked with the same reference symbols in the figures. In some figures, individual reference symbols have been omitted for clarity. The figures and the relative sizes of the elements depicted within them are not to be considered to scale. Rather, individual elements may be exaggerated for better representation and / or comprehensibility.

[0049] DETAILED DESCRIPTION OF EXAMPLES OF EXECUTION

[0050] Figure 2 shows a component 101, here a housing cover, an assembly 100, and a connecting seam 110 by which the component 101 was joined to another component 102, here a housing, by means of a beam welding process. In the view of Figure 2, the other component 102 is arranged below the component 101 and is therefore not shown. The connecting seam 110 consists of a single seam 111 and another single seam 112. The two single seams 111 and 112 together form three intersection points 118.

[0051] At one of these intersection points 118, shown enlarged in Figure 9, an end section 113 and another end section 115 of the single seam 111 overlap. The single seam 111 is tightly formed in a region of the end section 113 that extends from the intersection point 118 in a direction away from the end 114 of the end section 113. Likewise, the single seam 111 is tightly formed in a region of the other end section 115 that extends from the intersection point 118 in a direction away from the other end 116 of the other end section 115. The tightly formed region extends to and encloses the intersection point in each case. In the present case, the end 114 is formed by a weld end 107 of the single weld 111, while the further end 116 is formed by a weld start 106 of the single weld 111.All angles 119 between the two end sections 113, 115 at the intersection point 118 are on the order of 90 degrees. In Figure 2, a circular relief bore is arranged adjacent to the intersection point 118 and outside the sealing area to be sealed.

[0052] At another of the intersection points 118 from Figure 2, which is shown enlarged in Figure 8, an end section 113 of the further single weld 112 overlaps with a section 117 of the single weld 111. Section 117 is a section of a closed path formed by the single weld 111 along the circumference of the component 101. It is therefore not an end section. The single weld 111 is fully formed over this entire closed path. The further single weld 112 is fully formed in a region of the end section 113 that extends from the intersection point 118 in a direction away from the end 114 of the end section 113. In other words, the fully formed region extends to and includes the intersection point 118. In this case, the end 114 is formed by a weld end 107 of the further single weld 112.All angles 119 between the end section 113 and the section 117 at the intersection point 118 are on the order of 90 degrees. In Figure 2, a circular relief bore is arranged adjacent to the intersection point 118 and outside the sealing area to be sealed.

[0053] The third intersection point 118 from Figure 2 differs from the intersection point just described in that its end is formed by a weld start 106 of the further single weld 112. Due to the arrangement of these two intersection points 118, the further single weld 112 connects a partition between two tightly sealed chambers 104, 109 to the housing cover 101. The single weld 111, on the other hand, connects a circumference of the overall housing to the cover 101, with the overall housing being divided into the two chambers 104, 109 by the aforementioned partition. Both the overall housing and the two chambers 104, 109 are tightly sealed. For comparison, Figure 1 shows a similar setup to Figure 2, in which a component 101 was welded to another component along a connecting weld 110 in the welding direction 105.However, the connecting seam 110 of Figure 1 has no intersection points, which is why leaks can occur, as already explained.

[0054] Figures 3 and 4 illustrate different welding processes. Figure 3 shows an overlap welding process in which the components 101, 102 or workpieces to be joined overlap during welding. The laser beam 108 is directed onto a first surface of the first component 101 and creates a weld seam 110 that extends from the first surface through the first component 101 and into the second component 102. The second component 102 rests against a second surface of the first component 101 opposite the first surface. It may be necessary to hold or press the two components 101, 102 together before or during the welding process.

[0055] For comparison, Figure 4 shows a butt welding process in which the components 101, 102 or workpieces are arranged side by side in one plane. The laser beam 108 is directed onto the line of contact between the two components 101, 102 and creates a joining seam 110 along the line of contact, for example an I-seam, which fuses the two components 101, 102 together.

[0056] Figures 5 to 7 show various variations of intersection points 118, where two end sections 113, 115 of a weld seam 110 overlap. The corresponding ends 114, 116 of the two end sections 113, 115 are located at an edge 103 of the component 101, for example, a lid, and outside an area to be sealed by the weld seam 110. Figures 5 to 7 differ in that the end sections 113, 115 are either straight or curved. With various individual welds 111 and corresponding intersection points 118, it is possible to produce several independent, sealed chambers, each with its own lid, by overlap welding. The welding strategy can be adapted to any number of products with different contours. The required start and end areas of the weld seam can be adjusted to the available installation space and are therefore flexibly positionable.Depending on requirements, it can have various line geometries, whereby the angles between the end sections should ideally be 90°. The required installation space for the start-end area is, for example, smaller compared to the start-end area in friction stir welding.

[0057] The invention is not limited to the exemplary embodiments described therein. Rather, the invention encompasses every new feature as well as every combination of features, which in particular includes every combination of features in the exemplary embodiments and claims.

[0058] REFERENCE MARK

[0059] 100 arrangement

[0060] 101 Component / Housing cover

[0061] 102 Component / Housing

[0062] 103 Outlet area

[0063] 104th Chamber

[0064] 105 Welding direction

[0065] 106 Welding start

[0066] 107 Welding ends

[0067] 108 Laser beam

[0068] 109 other chambers

[0069] 110 Joining seam

[0070] 111 Single seam

[0071] 112 more single stitches

[0072] 113 Final section

[0073] 114 End

[0074] 115 further final section

[0075] 116 more ending

[0076] Section 117

[0077] 118 Intersection point

[0078] 119 angles

Claims

PATENT CLAIMS 1. Arrangement (100) comprising two components (101 , 102) which are joined together by means of a beam welding process, such that a connecting seam (110) is formed between the components (101 , 102), - wherein the connecting seam (110) has an end section (113) with an end (114) and a section (117), - wherein the section (117) and the end section (113) intersect at a crossing point (118), - wherein the connecting seam (110) is tightly formed in an area of ​​the end section (113) which extends from the intersection point (118) in a direction that points away from the end (114).

2. Arrangement according to the preceding claim, wherein the connecting seam (110) encloses a sealing area formed by a surface of one of the two components (101, 102), wherein the end (114) is arranged outside the sealing area.

3. Arrangement according to one of the preceding claims, wherein a first (102) of the two components forms a housing and the second (101) of the two components forms a housing cover.

4. Arrangement according to the preceding claim, wherein the housing (102) and the housing cover (101) form at least one sealed chamber (104, 109), in particular two or more sealed chambers (104, 109).

5. Arrangement according to the preceding claim, wherein the housing cover (101) forms an outlet area (103) outside the at least one sealed chamber (104, 109) in which the end is arranged.

6. Arrangement according to the preceding claim, wherein the outlet area (103) widens in the vicinity of the intersection point (118) and / or the outlet area (103) near the intersection point (118) has a relief hole.

7. Arrangement according to any one of claims 3 to 6, wherein the housing (102) and / or the housing cover (101) are made of aluminium.

8. Arrangement according to one of the preceding claims, wherein the section (117) is a further end section (115) with a further end (116), wherein the connecting seam (110) is tightly formed in a region of the further end section (115) which extends from the intersection point (118) in a direction that points away from the further end (116).

9. Arrangement according to any one of claims 1 to 7, wherein the section (117) is a section of a closed path which is part of the connecting seam (110), wherein the connecting seam (110) is tightly formed over the entire closed path.

10. Arrangement according to one of the preceding claims, wherein a region of the end section (113) between the intersection point (118) and the end (114) is longer than a weld indentation at a weld end (107) of the joining seam (110) and / or than a weld reinforcement at a weld start (106) of the joining seam (110).

11. Arrangement according to one of the preceding claims, wherein a region of the end section (113) between the intersection point (118) and the end (114) is at least as long as such that stresses caused by a weld start or a weld end at the end (114) do not interact with stresses at the intersection point (118).

12. Arrangement according to one of the preceding claims, wherein all angles between the end section (113) and the section (117) at the intersection point (118) are greater than 70 degrees and less than 110 degrees, in particular greater than 80 degrees and less than 100 degrees.

13. Arrangement according to one of the preceding claims, wherein the connecting seam (110) consists of at least two individual seams (111 , 112), each individual seam (111 , 112) having exactly two end sections (113, 115).

14. Arrangement according to one of the preceding claims, wherein the two components (101 , 102) overlap at the connecting seam (110), the connecting seam (110) extending through one of the components (101 ) into the other component (102).

15. Method for joining two components (101, 102) of an arrangement (100), comprising the following steps: - Forming a connecting seam (110) between the components (101 , 102) by means of a beam welding process, wherein the connecting seam (110) has an end section (113) with an end (114) and a section (117), wherein the section (117) and the end section (113) intersect at a crossing point (118), wherein the connecting seam (110) is tightly formed in a region of the end section (113) which extends from the crossing point (118) in a direction that points away from the end (114).

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