Hold-down device, laser beam welding device and method for laser beam welding

Abstract

The invention relates to a hold-down device (1). According to the invention, the hold-down device (1) has at least one hold-down unit (3) with a vertically movable holder (4) which has a hold-down pin receptacle (5) in which a hold-down pin (6) is arranged at a predetermined angle (δ) oblique to the vertical (V), wherein the hold-down pin (6) is mounted in the hold-down pin receptacle (5) so as to be displaceable upwards in the axial direction of the hold-down pin (6) against a spring force of a spring element (7). Furthermore, the invention relates to a laser beam welding device (2) and a method for laser beam welding.

Description

[0001] The invention relates to a hold-down device, a laser beam welding device and a method for laser beam welding.

[0002] From the prior art, as described in EP 0 456 142 A1, a pre-adjustable clamping device is known which is provided with an adjusting element by means of which clamping and adjustment of the spring force is carried out after assembly.

[0003] Japanese patent application JP HO1-218781A addresses the prevention of defective welds such as buckling and the butt welding of gaps on the end face using a laser beam. The gap in a butt joint is intermittently reshaped in the welding direction and welded with a laser beam. The upper part of the gap is larger than the lower part. The length of the butt joint between the gaps is less than twice the diameter of the laser beam. The lower part of the end face of the weld element is accessible using a knurling tool.

[0004] DE 102 58 928 A1 proposes a device for orbital joining of at least two plate-shaped workpieces, in particular sheets, together, comprising a base frame, a punch which can be moved towards or away from the workpieces along a main joining axis by means of an axial drive and which can be set into an orbital motion around the main joining axis by means of an orbital drive, and a counter-holder on the side of the workpieces opposite the punch. The punch and at least one orbital drive of the orbital drive are mounted on a joining head which is arranged at one end of a first arm extending transversely to the main joining axis, and the counter-holder is arranged at one end of a second arm extending transversely to the main joining axis, with the first and second arms being mounted on the base frame.

[0005] The invention is based on the objective of providing a hold-down device improved compared to the prior art, a laser beam welding device improved compared to the prior art and a method for laser beam welding improved compared to the prior art.

[0006] The object is solved according to the invention by a hold-down device with the features of claim 1, a laser beam welding device with the features of claim 7 and a method for laser beam welding with the features of claim 8.

[0007] Advantageous embodiments of the invention are the subject of the dependent claims.

[0008] A hold-down device according to the invention has at least one hold-down unit with a vertically movable holder which has a hold-down pin receptacle in which a hold-down pin, also referred to as a hold-down bolt, is arranged at a predetermined angle of, for example, 2° to 65° oblique to the vertical, wherein the hold-down pin is displaceably mounted in the hold-down pin receptacle in the axial direction of the hold-down pin against a spring force of a spring element upwards, i.e. obliquely upwards according to the predetermined angle.

[0009] The hold-down device can also have several of these hold-down units. For example, it can be provided that the holders of the hold-down units and / or the entire hold-down units are vertically movable independently of one another, and / or that the entire hold-down device with all hold-down units is vertically movable. Alternatively or additionally, the multiple hold-down units of the hold-down device can, for example, be movable relative to one another, particularly horizontally, in order to adjust their positioning relative to one another. Alternatively or additionally, for example, the entire hold-down device can be moved, particularly horizontally and / or vertically, in order to move it into and out of a processing area, particularly a welding area.

[0010] The hold-down pin has, in particular, a lower end, wherein the lower end of the hold-down pin is rounded, or a ball, in particular rotatably, is arranged at the lower end of the hold-down pin, or a component support element, which has a flat component support surface, is pivotably mounted at the lower end of the hold-down pin via a horizontal pivot axis, wherein the horizontal pivot axis is perpendicular to a virtual surface spanned by the hold-down pin and the vertical.

[0011] For example, the rounded lower end of the hold-down pin, or the ball or component support surface of the component support element has a roughened surface structure.

[0012] The retaining pin receptacle and / or the spring element are / are made, for example, of an electrically insulating material.

[0013] The hold-down pin contains, for example, a protective gas supply line and / or an extraction line.

[0014] A laser beam welding device according to the invention has such a hold-down device.

[0015] In a laser beam welding method according to the invention, a first component is arranged on a second component such that an overlap joint is formed. The first component is pressed against the second component by means of the hold-down device, and the two components are welded together by laser beam welding.

[0016] The first component is pressed against the second component, in particular by means of the hold-down device, by moving the hold-down pin receptacle, in particular the holder with the hold-down pin receptacle, vertically downwards with a predetermined vertical force, whereby the lower end of the hold-down pin or the ball or the flat component support surface of the component support element is pressed against a top surface of the first component with a contact force resulting from the predetermined vertical force and the spring force of the spring element, and thereby the first component is pressed against the second component with this contact force.

[0017] For example, before pressing the first component onto the second component using the hold-down device, or even before arranging the first component on the second component, a recess is formed at a designated hold-down point on the top of the first component.

[0018] The described solution is advantageously suited for joining components in a lap joint, i.e., in particular for welding lap joints, especially by laser beam welding. Laser beam welding, especially laser scanner welding, is characterized in principle by fast process times. By means of movable mirrors in a laser welding optic, a laser beam can be moved at high speed within the scan field from one weld point to the next by superimposing a movement of the laser welding optic. This is also known as welding-on-the-fly. However, this movement is currently severely restricted, especially with a large number of joining points, by conventional hold-down concepts and structures and the associated shadowing of the laser beam, thus negating the advantage of the fast process time. This disadvantage is eliminated by the solution described here.

[0019] Furthermore, laser beam welding of overlapping components requires a zero-gap welding process across the entire weld area, as any remaining gap can otherwise lead to weld imperfections. Conventional weld clamps are known in the prior art, but these may compress the components insufficiently and only on one side, leaving an unwanted gap. Spring-loaded clamps with vertical force application, also known in the prior art, offer poor accessibility for the laser beam. Moreover, the clamping force varies with different component heights due to the springs used, and may become insufficient.

[0020] The described solution, in particular the described hold-down device, enables good accessibility of the laser beam to the components in various geometries with fast processing time, especially through the inclined positioning of the hold-down pin.

[0021] The hold-down pin advantageously has a point bearing surface and a pin-, bolt-, or finger-like contour. It is spring-mounted and arranged at a predetermined angle to the vertical and thus also to the component's normal plane. It therefore exerts a corresponding force on the components and, due to its angled position, enables a particularly advantageously larger welding area.

[0022] The contact area of ​​the hold-down pin is designed, for example, with a ball or a joint or similar, in particular as described above, to ensure optimal pressing motion of the first component, so that a relative movement can take place between the first component and the hold-down pin in the contact area.

[0023] The alignment of the hold-down pin is advantageously carried out with the bearing area, i.e. with its lower end, towards a free component end in order to achieve optimal hold-down properties on the one hand and to create a technically zero gap in the component connection, which is important for the strength of the weld.

[0024] This tilting of the hold-down pin at the specified angle allows for a significantly larger beam incidence area of ​​the laser beam, resulting in faster cycle times, especially in multiple applications of the hold-down units.

[0025] As previously described, a recess can be formed at the intended hold-down point on the top surface of the first component. This recess allows for optimal positioning of the hold-down pin and, for example, further flexibility.

[0026] As also mentioned previously, the rounded lower end of the hold-down pin or the ball or component support surface of the component support element may have a roughened surface structure to achieve improved adhesion at the hold-down point.

[0027] The described solution allows for an increase in the welding area and more flexible design options for weld seams.

[0028] In laser beam welding, the described solution enables optimal utilization of the scan field of the laser welding optics through the inclined positioning of the hold-down pin, thus resulting in fast process times, improved accessibility and a reduction in cycle time.

[0029] The described solution enables very good hold-down properties, in particular the creation of the technical zero gap, since each individual joining point is acted upon by a single hold-down unit and its hold-down pin.

[0030] The described solution enables good tolerance compensation in the vertical direction, particularly through the spring-loaded retaining pin.

[0031] Advantageously, the hold-down pin and / or the hold-down unit is replaceable, thus enabling easy maintenance, for example in case of contamination.

[0032] The hold-down device, in particular the hold-down unit, especially its hold-down pin and / or the holder, especially its hold-down pin receptacle, is / is made, for example, of lightweight materials, such as aluminum or other materials. A mixed construction is also possible. This results in only low moving masses, enabling high dynamics.

[0033] The described solution enables the welding of all materials. It is particularly suitable for laser beam welding of metallic materials, especially for contacting cell connector units with the battery cell terminals of a battery, particularly a traction battery for a vehicle.

[0034] The described solution can be used for various welded joints, especially for overlap welds.

[0035] The described solution is scalable for large and small components, for example also by a method of the hold-down device or the hold-down unit or several hold-down units in the hold-down device.

[0036] Providing multiple hold-down units in a common hold-down device can also contribute to increased productivity.

[0037] For example, the protective gas supply and extraction can also be integrated into the hold-down device, in particular into the hold-down unit, especially into its hold-down pin.

[0038] Exemplary embodiments of the invention are explained in more detail below with reference to drawings.

[0039] This shows: Fig. 1. Schematic representation of a process for laser beam welding, Fig. 2 schematically a top view of a first component pressed onto a second component by means of a hold-down unit of a hold-down device, Fig. 3 schematically an embodiment of the hold-down unit, Fig. 4 schematically shows another embodiment of the hold-down unit, and Fig. 5 schematically shows another embodiment of the hold-down unit.

[0040] Corresponding parts are marked with the same reference symbols in all figures.

[0041] Based on the Fig. Sections 1 to 5 below describe a hold-down device 1, a laser beam welding device 2, and a method for laser beam welding a first component B1 to a second component B2. Fig. 1. An exemplary sequence of the procedure, Fig. Figure 2 shows a top view of the first component B1 pressed onto the second component B2 by means of a hold-down unit 3 of the hold-down device 1 and the Fig. Figures 3 to 5 show exemplary embodiments of the hold-down device 1, in particular the hold-down unit 3.

[0042] The orientation of each component shown is clarified by a y-axis Y, z-axis Z and x-axis X of a coordinate system that is also shown.

[0043] The hold-down device 1 comprises at least the hold-down unit 3, which is located in the Fig. Numbers 1 to 5 are shown.

[0044] The hold-down unit 3 has a vertically movable holder 4, which has a hold-down pin receptacle 5 in which a hold-down pin 6 is arranged at a predetermined angle δ of, for example, 2° to 65° obliquely to the vertical V and thus also obliquely to a component normal plane BN of the second component B2. The hold-down pin 6 is slidably mounted in the hold-down pin receptacle 5 in its axial direction against a spring force of a spring element 7 upwards, i.e., obliquely upwards according to the predetermined angle δ.

[0045] The laser beam welding device 2 includes the hold-down device 1. Furthermore, the laser beam welding device 2 includes, in particular, a laser beam generation unit (not shown) for generating a laser beam LS for welding the two components B1 and B2, and laser welding optics (not shown) for moving the laser beam LS, as shown in Fig. 1 shown on the right.

[0046] In the Fig. In the exemplary method for laser beam welding shown in 1 using the laser beam welding device 2, the first component B1 is arranged on the second component B2 in such a way that an overlap joint is formed.The first component B1 is pressed against the second component B2 by means of the hold-down device 1. This is achieved by moving the holder 4 with the hold-down pin receptacle 5 vertically downwards with a predetermined vertical force F. This causes a lower end 8 of the hold-down pin 6, or a ball 9 (described in more detail below) at the lower end 8 of the hold-down pin 6, or a flat component support surface 10 of a component support element 11 (described in more detail below) at the lower end 8 of the hold-down pin 6, to be pressed against a top surface of the first component B1 with a contact force resulting from the predetermined vertical force F and the spring force of the spring element 7. This contact force presses the first component B1 against the second component B2. Subsequently, the two components B1 and B2 are welded together by laser beam welding.

[0047] The alignment of the hold-down pin 6 is advantageously carried out with the bearing area, i.e. with its lower end 8, towards a free component end FE of the first component B1, in order to achieve optimal hold-down properties on the one hand and to create a technically zero gap of the component connection which is important for the strength of the weld.

[0048] The inclined position of the retaining pin 6 with the specified angle δ allows for an advantageously larger beam incidence area of ​​the laser beam LS, as shown in Fig. 1 shown on the right, and therefore also an enlarged welding area VB, as in Fig. 2 shown, which allows for faster cycle times.

[0049] As mentioned above, the hold-down pin 6 has the lower end 8. In the example according to Fig. 1 as well as in the Fig. In the embodiment shown in Figure 3, this lower end 8 is rounded.

[0050] Fig. Figure 4 shows a further embodiment in which the aforementioned ball 9 is arranged, in particular rotatably, at the lower end 8 of the retaining pin 6.

[0051] Fig. Figure 5 shows a further embodiment in which the aforementioned component support element 11, which has the flat component support surface 10, is pivotably mounted at the lower end 8 of the hold-down pin 6 via a horizontal pivot axis S, wherein the horizontal pivot axis S runs perpendicular to a virtual surface spanned by the hold-down pin 6 and the vertical V. This forms a pivot joint between the lower end 8 of the hold-down pin 6 and the component support element 11.

[0052] For example, the rounded lower end 8 of the hold-down pin 6 or the ball 9 or the component support surface 10 of the component support element 11 has a roughened surface structure.

[0053] For example, before pressing the first component B1 onto the second component B2 using the hold-down device 1, or even before arranging the first component B1 on the second component B2, a component recess BA is formed at a designated hold-down point on the top side of the first component B1, as shown in Fig. 3 shown.

[0054] The retaining pin receptacle 5 and / or the spring element 7 are / are made, for example, of an electrically insulating material.

[0055] For example, a protective gas supply line and / or an extraction line are arranged or formed in the retaining pin 6.

Claims

[1] Hold-down device (1) of a joining device, characterized by at least one hold-down unit (3) with a vertically movable holder (4) which has a hold-down pin receptacle (5) in which a hold-down pin (6) is arranged at a predetermined angle (δ) oblique to the vertical (V), wherein the hold-down pin (6) is mounted in the hold-down pin receptacle (5) so as to be displaceable upwards in the axial direction of the hold-down pin (6) against a spring force of a spring element (7). [2] Hold-down device (1) according to claim 1, characterized by , that the specified angle (δ) is between 2° and 65°. [3] Hold-down device (1) according to one of the preceding claims, characterized by , that the retaining pin (6) has a lower end (8), wherein - the lower end (8) of the retaining pin (6) is rounded, or - a ball (9) is rotatably mounted at the lower end (8) of the retaining pin (6), or - a component support element (11) which has a flat component support surface (10) is pivotably mounted at the lower end (8) of the hold-down pin (6) via a horizontal pivot axis (S), wherein the horizontal pivot axis (S) is perpendicular to a virtual surface spanned by the hold-down pin (6) and the vertical (V). [4] Hold-down device (1) according to claim 3, characterized by , that the rounded lower end (8) of the hold-down pin (6) or the ball (9) or the component support surface (10) of the component support element (11) has a roughened surface structure. [5] Hold-down device (1) according to any one of the preceding claims, characterized by that the retaining pin receptacle (5) and / or the spring element (7) are made of an electrically insulating material. [6] Hold-down device (1) according to any one of the preceding claims, characterized by , that a protective gas supply line and / or a suction line are arranged or formed in the hold-down pin (6). [7] Laser beam welding device (2) comprising a hold-down device (1) according to one of the preceding claims. [8] Method for laser beam welding using a laser beam welding device (2) according to claim 7, wherein a first component (B1) is arranged on a second component (B2) such that an overlap joint is formed, the first component (B1) is pressed against the second component (B2) by means of the hold-down device (1) and the two components (B1, B2) are welded together by laser beam welding. [9] Method according to claim 8, characterized by, that the first component (B1) is pressed against the second component (B2) by means of the hold-down device (1) by moving the holder (4) with the hold-down pin receptacle (5) vertically downwards with a predetermined vertical force (F), whereby the lower end (8) of the hold-down pin (6) or the ball (9) or the flat component support surface (10) of the component support element (11) is pressed against a top surface of the first component (B1) with a contact force resulting from the predetermined vertical force (F) and the spring force of the spring element (7), and thereby the first component (B1) is pressed against the second component (B2) with this contact force. [10] Method according to claim 8 or 9, characterized by , that before pressing the first component (B1) onto the second component (B2), a component recess (BA) is formed at a designated hold-down point on the top side of the first component (B1).

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