Device for laser welding and laser soldering

Abstract

Device for laser welding and / or laser soldering (100a), comprising a device for guiding a light beam (200a) with a focusing optic (210a, 210b) and a deflecting optic arranged downstream along a propagation direction of the light beam and rotatable about a rotational axis, wherein the deflecting optics are designed to guide the light beam, when driven in a rotating manner, along a circular path perpendicular to the direction of propagation, such that a radius of the weld path (150a, 150b) is smaller than a radius of a circle which the light beam describes when exiting the deflecting optics, and wherein the focusing optics (210a, 210b) are configured to focus the light beam so that it has a focus diameter between 50 µm and 500 µm on the circular path, the deflection optics consist only of a wedge plate (250a, 250b) and no other optical components, wherein the wedge plate (250a, 250b) is formed by two optical elements (260a, 260b, 270a, 270b) and has two planar surfaces as end faces (262a, 272a), wherein the optical elements of the wedge plate have complementary spherical surfaces (264a, 274a) facing each other, one of which spherical surfaces (264a) forms a concave surface of the first optical element (260a, 260b) and the second spherical surface (274a) forms a convex surface of the second optical element (270a, 270b), and the concave surface and the convex surface have the same radius of curvature and are to be shifted relative to each other along the mutually facing spherical surfaces (264a, 274a) such that the planar surfaces (262a, 272a), as surfaces facing away from the respective spherical surface (264a, 274a) of a respective optical element, run at an angle to each other, wherein the optical element (270a, 270b) of the wedge plate (250a, 250b), which is not the first to be hit by the light beam, is adjustable by means of a shaft with worm gear, wherein the upper surface (262a) of the wedge plate (250a, 250b) is installed at an angle to the light beam.

Description

[0001] The invention relates to a device for laser welding.

[0002] From DE 20 2008 017 745 U1, a device for guiding a light beam with a rotatingly driven light guiding element and at least one optical group is known. This optical group is formed from two optical elements and has two flat surfaces as end faces.

[0003] In contrast, DE 10 2005 047 328 B3 describes a device for drilling and material removal using a laser beam, which consists of a large number of components, namely a rotating image rotator, a beam manipulator, a focusing device and a compensation device, wherein the compensation device in turn has a parallel offset unit and an angle change unit.

[0004] Welding devices are used in a variety of ways to join workpieces. For example, a bolt can be welded to a base using electric arc welding. This involves creating an arc by connecting or contacting a ground wire to the workpiece and guiding an electrode at a defined distance between the electrode tip and the workpiece. The materials to be joined melt at the joint and, upon solidification, form a weld seam through mixing. This requires, on the one hand, the presence of uninsulated areas, and on the other hand, it is not possible to join particularly sensitive components using this technique because the arc temperature is difficult to control. Another problem is the continuous adjustment of the guide electrode's distance due to the constant wear of the electrode.If a fillet weld is to be carried out around a bolt, this results in considerable control effort in industrial manufacturing, both for moving workpieces and for moving electrodes.

[0005] Ideally, the components should be joined using a suitable method that withstands the necessary loads and prevents damage to the components. Furthermore, the control and regulation effort should be kept to a minimum to ensure a reliable process. Finally, a device with the fewest possible components should be provided.

[0006] The object of the invention is to provide a device that fulfills as many of these wishes as possible.

[0007] This is achieved according to the invention by a device for laser welding and / or laser soldering according to claim 1. Advantageous embodiments can be obtained, for example, from the dependent claims.

[0008] The invention relates to a device for laser welding and / or laser brazing. This device comprises a device for guiding a light beam with a focusing optic and a deflecting optic arranged downstream along the direction of propagation of the light beam and driven or rotated about an axis of rotation. The deflecting optic is designed to guide the light beam, when driven to rotate, along a circular path transverse to the direction of propagation such that the radius of the circular path is smaller than the radius of an exit circle described by the light beam upon exiting the deflecting optic. Thus, the light beam is angled inwards – viewed in the direction of the beam and with respect to the weld path. Furthermore, variable focusing systems can be used to focus the light beam so that the required focus diameter for welding and / or brazing can be achieved on the workpiece.Preferably, the focusing optics are designed to focus the light beam so that it has a focus diameter between 50 µm and 500 µm on the circular path.

[0009] The circular path is preferably the same as a welding path along which welding is to be carried out.

[0010] The device according to the invention makes it possible to weld a component, such as a round bolt, onto a base by guiding a laser beam along the intended weld seam. The laser beam locally heats the material of both workpieces, thereby liquefying the areas struck by the laser beam and those adjacent to it. The mixing of the material, which then immediately re-hardens, creates a bond between the workpieces. This process eliminates the need for electrical current, as required in electric welding, or flames, as is typical in welding with flammable gases. Thus, the device according to the invention enables particularly simple and gentle welding and / or brazing without the need for complex control systems.

[0011] The device for guiding a light beam essentially fulfills two functions, namely focusing and directing the light beam, which is preferably a laser beam.

[0012] First, the light beam is focused. This is done by the focusing optics. In the simplest case, the focusing optics are designed as a focusing lens. Alternatively, however, the focusing optics can also be designed as a lens system and / or a mirror system. In this case, more complex optics can be used.

[0013] In one embodiment, the focusing optics are driven in rotation together with the deflecting optics. This allows the focusing optics to be integrated into a single optical component. In an alternative embodiment, the focusing optics are stationary and are therefore not driven in rotation together with the deflecting optics. This reduces the mass that needs to be driven in rotation by a single drive mechanism, and in this embodiment, the incident light beam strikes a non-rotating and therefore completely constant surface. This prevents unwanted displacements of the light beam.

[0014] After focusing, the device for guiding a light beam also has the task of guiding the light beam along the weld path in such a way that its radius is smaller than the radius of the circle that the light beam describes when exiting the deflecting optics, so that the light beam can, for example, strike an angle between a cylindrical bolt and a flat surface on which the bolt stands. The device incorporates the deflecting optics for this purpose.

[0015] According to the invention, the deflection optic consists solely of a wedge plate and has no other optical components. In this case, the wedge plate can be used both to parallelize the light beam and to deflect it. Typically, for this purpose, an upper surface of the wedge plate is not installed perpendicular to the light beam, but at an angle to it. This results in the same beam path as when using a plane-parallel plate and a downstream wedge plate.

[0016] The wedge plate is formed by two optical elements and has two planar surfaces as end faces. The optical elements of the wedge plate have complementary spherical surfaces facing each other, one of which forms a concave surface of the first optical element and the other a convex surface of the second optical element. The concave and convex surfaces have the same radius of curvature. Furthermore, the optical elements of the wedge plate are preferably displaced relative to each other along their facing spherical surfaces such that the planar surfaces facing away from the respective spherical surface of each optical element are at an angle to each other.

[0017] Such a wedge plate design requires only two optical elements whose concave and convex surfaces directly adjoin each other, achieving the desired effect on the light beam. If the end face of the optical element first struck by the light beam is perpendicular to the beam, the light beam is initially not deflected by this first optical element. However, if this optical element is positioned so that its end face is oblique to the light beam, the light beam is deflected from its direction of propagation as soon as it enters the wedge plate. This achieves an effect similar to that of parallel offset using a plane-parallel plate positioned upstream.

[0018] When the light ray reaches the spherical surface of the optical element it entered, it strikes the next optical element, for example, the second one, typically its spherical surface facing the first optical element, which is spaced at a distance. The radius of the spherical surface of the first optical element is equal to the radius of the spherical surface of the next optical element. Thus, the effects of the spherical surfaces cancel each other out. The adjacent spherical surfaces therefore serve to allow movement or adjustment of the orientations of the two optical elements relative to each other. When the light ray strikes the other end face of the wedge plate, it is deflected again; the angle between the two flat surfaces describes the wedge angle.This sets an angle relative to its original direction of propagation.

[0019] The deflecting optics are preferably designed such that the angle of the light beam relative to the axis of rotation upon exiting the deflecting optics is adjustable. This can preferably be achieved by making the wedge plate or one of the optical elements of the wedge plate adjustable. According to the invention, the optical element of the wedge plate that is not the first to be struck by the light beam is designed to be adjustable.

[0020] The adjustability can be designed by means of mechanical devices such that the angle can only be adjusted when the device is not rotating. Alternatively, however, means can also be provided that allow the angle to be adjusted even during rotation, i.e., during operation. According to the invention, a shaft with a worm gear is provided for this purpose.

[0021] Regardless of whether the angle of the light beam exiting the deflecting optics is fixed or adjustable, it preferably assumes an angle between 10 and 15 degrees, preferably between 12 and 13 degrees, and most preferably 12.5 degrees relative to the axis of rotation. These values ​​have proven suitable for many applications in practice.

[0022] According to a preferred embodiment, the device according to the invention further comprises a laser for generating the light beam. In one embodiment, the direction of incidence of the light beam is parallel to the axis of rotation. Alternatively, however, the direction of incidence of the light beam can also be angled to the axis of rotation.

[0023] The laser preferably has a power output of at least 100 watts. Higher power lasers, for example of several hundred watts or even more than 1000 watts, can also be used. Preferably, however, a power output of several thousand watts, for example 5000 watts, is not exceeded.

[0024] Furthermore, the laser is preferably non-pulsed. However, systems with a high repetition rate can also be used for certain applications. In this case, the laser preferably has a repetition rate between 100 Hz and 1 MHz.

[0025] The device is preferably driven at a rotational speed of at least 100 revolutions per minute, and particularly preferably at several hundred revolutions per minute. A rotational speed of 6000 revolutions per minute is preferably not exceeded.

[0026] Preferably, the focusing optics are designed to be adjustable, particularly preferably in the direction of the axis of rotation and further preferably also during operation of the device. This makes it possible to adjust the focus diameter. This allows the device to be adapted to different workpieces being machined.

[0027] It should be noted that all the specified numerical values ​​are those that have proven advantageous in the past. This does not preclude the use of values ​​for power, repetition rate, and rotational speed that lie outside the specified ranges for specific applications. The crucial factor, as a rule, is to adjust the values ​​so that the material is heated evenly, gently, and sufficiently along the weld seam.

[0028] Further features and instances of the invention will become obvious to the person skilled in the art when considering the exemplary embodiments which are described below with reference to the accompanying figures. Fig. Figure 1 shows an exemplary device for laser welding. Fig. Figure 2 shows a first embodiment of the invention. Fig. Figure 3 shows a second embodiment of the invention.

[0029] Fig. Figure 1 shows a device for laser welding 100. The device has a laser 110 which emits a laser beam 120. The laser beam 120 is deflected by a device 200 for guiding a light beam and then strikes a welding line 150, which is located between a first workpiece 130 and a second workpiece 140.

[0030] The second workpiece 140 is a bolt which is to be welded to the first workpiece 130 using the laser welding device 100.

[0031] Accordingly, the laser beam 120 is to be guided along the welding line 150 in a circular path. Achieving this is the task of the laser welding device 100, and in particular of the device 200 for guiding a light beam.

[0032] The device 200 for guiding a light beam has a focusing lens 210. The laser beam 120 strikes this lens first. The laser 110 and the focusing lens 210 are arranged relative to each other such that the laser beam 120 strikes the center of the focusing lens 210. The laser beam 120 is therefore not deflected by the focusing lens 210, but merely focused. The focusing lens 210 is designed such that when the laser beam 120 strikes the weld line 150, it has a corresponding focus diameter, for example, of 100 µm.

[0033] After passing through the focusing lens 210, the laser beam 120 strikes a plane-parallel plate 220. The plane-parallel plate 220 has two mutually parallel surfaces: a first surface 222 and a second surface 224. When the laser beam 120 strikes the plane-parallel plate 220, it first encounters the first surface 222. Since the refractive index for the laser beam 120 increases upon entering the plane-parallel plate 220, it is refracted towards the normal of the first surface 222. It then travels straight through the plane-parallel plate 220 and then encounters the second surface 224. At this second surface 224, the laser beam 120 exits the plane-parallel plate 220, causing the refractive index to decrease. Therefore, upon exiting the second surface 224, the laser beam 120 is refracted away from the normal and then travels parallel to its original direction of propagation.However, compared to the original direction of propagation, the laser beam is offset by 120 degrees.

[0034] The laser beam 120 then strikes a wedge plate 250. The wedge plate 250 consists of a first optical element 260 and a second optical element 270. The first optical element 260 has a first end face 262, which the laser beam 120 initially strikes. The first end face 262 is planar and perpendicular to the propagation direction of the laser beam 120, which is why the propagation direction of the laser beam 120 does not change upon entering the first optical element 260, despite the higher refractive index. The laser beam then passes straight through the first optical element 260 and strikes a first spherical surface 264, at which the first optical element 260 abuts a second spherical surface 274 of the second optical element 270 with minimal surface area.Since the two spherical surfaces 264, 274 are complementary to each other and directly adjacent to each other, the laser beam 120 enters the second optical element with minimal change.

[0035] After passing through the second optical element 270, it encounters a second end face 272 of the second optical element 270, at which it exits the second optical element 270. Upon exiting the second optical element 270, the refractive index decreases again, causing the laser beam 120 to be refracted away from the normal of the second end face 272. In doing so, the laser beam 120 is angled so that it is directed towards the weld line 150.

[0036] The angle at which the laser beam 120 is deflected upon exiting the wedge plate 250 can be adjusted using an adjustment device 300. The adjustment device 300 is located in the beam guiding device 200 and comprises a stepper motor 310, a threaded rod 320, and a driver 330. The driver 330 is connected to the second optical element 270. By rotating the threaded rod 320 with the aid of the stepper motor 310, the driver 330 can be moved along a line. This changes the angle of the second end face 272 relative to the first end face 262, with the two spherical surfaces 264, 274 remaining directly adjacent to each other. In this way, the exit angle of the laser beam 120 can also be adjusted during operation.

[0037] A drive unit 400 serves to drive the device 200 for guiding a light beam. The drive unit 400 enables the device 200 to be set into rotation. The drive unit 400 comprises a motor 410, which is connected to a wheel 430 via a shaft 420. The wheel 430 is adjacent to the side of the device 200 for guiding a light beam. This allows a rotational movement of the wheel 430 to be transmitted to the device 200 for guiding a light beam. When the wheel 430 is set into rotation by the motor 410, the device 200 for guiding a light beam is also driven in a rotating manner.

[0038] A possible alternative design of a drive unit, which is not shown, would be a hollow shaft drive.

[0039] Since the deflection of the laser beam 120 described above in the first plane-parallel plate 220 and the wedge plate 250 depends on the respective position in relation to the rotational movement of the device 200 for guiding a light beam, the laser beam 120 is guided on a circular path along the weld line 150.

[0040] Fig. Figure 2 shows a first embodiment of the invention. A device for laser welding 100a is shown. Components already used in connection with Fig. 1 mentioned and in the presentation of Fig. Two functions that are identical or similar are marked with the letter "a".

[0041] The laser welding device 100a also includes a laser 110a which emits a laser beam 120a. The laser beam 120a strikes a weld line 150a between a first workpiece 130a and a second workpiece 140a. This is achieved by a device 200a for guiding a light beam with a focusing lens 210a and a wedge plate 250a. In contrast to the first embodiment of Fig. However, 1 shows the device for laser welding 100a from Fig. 2 no longer uses a wedge plate. Instead, the deflection of the light beam is achieved exclusively by the wedge plate 250a.

[0042] The wedge plate 250a consists of a first optical element 260a with a first end face 262a and a first spherical surface 264a, and a second optical element 270a with a second end face 272a and a second spherical surface 274a. In this respect, the wedge plate 250a is very similar to the wedge plate 250 of Fig. 1. The only difference is that in the case of wedge plate 250a of Fig. 2. The first optical element 260a is arranged such that the first end face 262a is no longer perpendicular to the incident laser beam 120a. This causes the laser beam 120a to be deflected upon entering the first optical element 260a. It then passes through the adjacent spherical surfaces 264a and 274a without being deflected and finally strikes the second end face 272a. Since the refractive index decreases again at the second end face 272a upon exiting the second optical element 270a, the laser beam 120a is deflected away from the normal and attains the desired angle to strike the weld line 150a.

[0043] Just like in Fig. In the first embodiment shown in Figure 1, the device 210a for guiding a light beam can be driven by means of a drive unit 400a. Furthermore, the angle of the laser beam 120a at the exit from the second optical element can be adjusted by means of an adjustment device 300a.

[0044] The second embodiment thus demonstrates the same functionality as the first embodiment, but achieves this without a plane-parallel plate.

[0045] Fig. Figure 3 shows a second embodiment of the invention. This embodiment comprises a focusing optic 210b and a wedge plate 250b with a first optical element 260b and a second optical element 270b. A laser beam 120b strikes these elements and is focused and deflected, as already described with reference to the focusing optics 210, 210a and the wedge plates 250, 250a.

[0046] Furthermore, after passing through the focusing optics 210b and the wedge plate 250b, the laser beam strikes a first deflection mirror 500b and a second deflection mirror 550b, which rotate with the wedge plate 250b. The laser beam is first reflected or deflected by the first deflection mirror 500b and then by the second deflection mirror 550b. After deflection by the second deflection mirror 550b, it strikes a weld line 150b, located between a first workpiece 130b and a second workpiece 140b, at an angle adjustable by the wedge plate 250b and the two deflection mirrors 500b and 550b. By using the deflecting mirrors 500b, 550b, the radius of the weld line 150b can be increased, since the light beam is first directed radially outwards by the first deflecting mirror 500b before it is directed onto the weld line 150b by the second deflecting mirror 550b.Furthermore, this can also achieve a reduction in building height.

Claims

[1] Device for laser welding and / or laser soldering (100a), comprising a device for guiding a light beam (200a) with a focusing optic (210a, 210b) and a deflecting optic arranged downstream along a propagation direction of the light beam and rotatable about an axis of rotation, wherein the deflecting optics are designed to guide the light beam, when driven in a rotating manner, along a circular path perpendicular to the direction of propagation, such that a radius of the weld path (150a, 150b) is smaller than a radius of a circle which the light beam describes when exiting the deflecting optics, and wherein the focusing optics (210a, 210b) are configured to focus the light beam so that it has a focus diameter between 50 µm and 500 µm on the circular path, the deflection optics consist only of a wedge plate (250a, 250b) and no other optical components, wherein the wedge plate (250a, 250b) is formed by two optical elements (260a, 260b, 270a, 270b) and has two planar surfaces as end faces (262a, 272a), wherein the optical elements of the wedge plate have complementary spherical surfaces (264a, 274a) facing each other, one of which spherical surfaces (264a) forms a concave surface of the first optical element (260a, 260b) and the second spherical surface (274a) forms a convex surface of the second optical element (270a, 270b), and the concave surface and the convex surface have the same radius of curvature and are to be shifted relative to each other along the mutually facing spherical surfaces (264a, 274a) such that the planar surfaces (262a, 272a), as surfaces facing away from the respective spherical surface (264a, 274a) of a respective optical element, run at an angle to each other, wherein the optical element (270a, 270b) of the wedge plate (250a, 250b), which is not the first to be hit by the light beam, is adjustable by means of a shaft with worm gear, wherein the upper surface (262a) of the wedge plate (250a, 250b) is installed at an angle to the light beam. [2] Device (100a) according to claim 1, wherein the deflecting optics are configured to guide the light beam such that, upon exiting the deflecting optics, it has an angle to the axis of rotation between 10° and 15°. [3] Device (100a) according to one of claims 1 or 2, wherein the deflecting optics are configured to adjust the angle which the light beam has to the axis of rotation when exiting the deflecting optics. [4] Device (100a) according to one of claims 1 to 3, which further comprises a laser (110a) for generating the light beam. [5] Device (100a) according to claim 4, wherein one direction of incidence of the light beam is parallel to the axis of rotation. [6] Device (100a) according to claim 4, wherein one direction of incidence of the light beam is angled to the axis of rotation. [7] Device (100a) according to any one of claims 4 to 6, wherein the laser (110a) is either non-pulsed or pulsed and has a repetition rate between 100 Hz and 1 MHz. [8] Device (100a) according to any one of claims 1 to 7, wherein the focusing optics is a focusing lens (210a, 210b) or a lens system. [9] Device (100a) according to any one of claims 1 to 8, wherein the focusing optics are stationary and are not driven rotating together with the deflecting optics. [10] Device (100a) according to any one of claims 1 to 9, wherein the focusing optics (210a, 210b) are adjustable in the direction of the axis of rotation.

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