Method for gluing metal parts

Abstract

The present disclosure relates to a method of gluing a first metal component to another component, the method comprising the steps of (a) providing a first metal component, such as a steel component, and another component, such as a second metal component, (b) treating a surface portion of the first metal component intended for gluing to the other component with a laser pulse, (c) applying a laser pulse to the surface portion of the first metal component such that a surface layer of the first metal component across the surface portion is removed preferably by ablation, (c) also applying a pressurized air or gas flow to the surface portion of the first metal component while applying the laser pulse to the surface portion, (d) applying an adhesive to at least the surface portion of the first metal component and / or to the surface of the further component, and (e) gluing the first metal component and the further component together.

Description

Technical Field

[0001] The present disclosure relates to a method of gluing a first metal component to another component, such as a second metal component, wherein at least a surface portion of the first metal component is treated with laser pulses to activate the outer metal surface prior to applying the adhesive. Background Art

[0002] It is known to prepare a surface portion of a first metal part intended for gluing to another part with laser pulses to remove contaminants on the surface of the metal surface and to activate the metal surface so that the glue will adhere better to the metal surface. Document EP 3 792 323 A1 generally describes such a gluing method.

[0003] It is generally desirable to improve gluing methods involving treatment of metal surfaces with laser pulses, in particular to improve such gluing methods with respect to the resulting purity of the activated metal surface and to improve the durability of the adhesive connection. Summary of the invention

[0004] According to at least one aspect, a method for gluing a first metal component to another component is proposed, the method comprising the following steps: (a) providing a first metal component such as a steel component and another component such as a second metal component, (b) treating a surface portion of the first metal component intended for gluing to the other component with a laser pulse so that a surface layer of the first metal component across the surface portion is removed, preferably by ablation, (c) applying a pressurized air or gas flow to the surface portion while applying the laser pulse to the surface portion of the first metal component, (d) applying an adhesive to at least the surface portion of the first metal component and / or to the surface of the other component, and (e) gluing the first metal component and the other component together.

[0005] According to at least one aspect, a method for manufacturing a personal care device includes the step of gluing a steel shaft into a metal cap, the method including the steps of: (a) providing the steel shaft and the metal cap, the metal cap being sized to receive at least the end region of the steel shaft, (b) treating a surface portion of the steel shaft intended for gluing to the metal cap with a laser pulse so that a surface layer from the steel shaft across the surface portion is removed, preferably by ablation, (c) applying a pressurized air or gas flow to the surface portion while treating the surface portion of the steel shaft with the laser pulse, (d) treating at least a portion of an inner surface of the metal cap intended for gluing to a corresponding surface portion of the steel shaft with a laser pulse, (e) applying an adhesive to the surface portion of the steel shaft and / or to the portion of the inner surface of the metal cap, and (f) fitting the metal cap to the steel shaft and curing the adhesive. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] The present disclosure will be further clarified by a detailed description of exemplary embodiments and with reference to the accompanying drawings. In the accompanying drawings,

[0007] Figure 1 is a cross-sectional profile through an example apparatus for treating a surface portion of a first metal component with a laser pulse while simultaneously applying a pressurized air or gas stream;

[0008] Figure 2 is a cross-sectional section through another example apparatus for treating a surface portion of a first metal component with a laser pulse while simultaneously applying a pressurized air or gas stream;

[0009] Figure 3 is a depiction of a simulation of a pressurized air or gas flow directed toward a first metal component having a surface portion to be treated with a laser pulse;

[0010] Figure 4 is derived from two different simulations for Figure 3 a depiction of the static pressure of a pressurized air or gas flow on a surface portion of a first metal component of the device depicted in;

[0011] Figure 5A is a SEM picture of a surface portion of a first metal component treated with a laser pulse without applying a pressurized air or gas flow;

[0012] Figure 5B is a SEM picture of a surface portion of a first metal component treated with a laser pulse while applying a pressurized air or gas stream;

[0013] Fig. 6A is a photograph of a first metal component, specifically a steel shaft, having a surface portion treated with laser pulses without applying a pressurized air or gas stream, and wherein the adhesive connection to the metal cap is tested with a hammering method as explained in the description;

[0014] Figure 6B is a photograph of a first metal component, in particular a steel shaft, having a surface portion treated with laser pulses with simultaneous application of a pressurized air or gas stream, and wherein the adhesive connection to the metal cap is tested with the hammering method as explained in the description;

[0015] Figure 7 shows a perspective view onto an example nozzle segment of a pressurized air or gas delivery system;

[0016] Fig. 8A is a depiction of an example personal care device; and

[0017] Figure 8B yes Fig. 8A An enlarged view of a personal care device of FIG. 1 , shown in a partially cut-away open state, wherein a cross-sectional section through a metal cap glued to a steel shaft is visible. DETAILED DESCRIPTION

[0018] Although it has been envisaged to perform laser pulse treatment of metal surfaces under an extraction hood or more locally provided exhaust system to remove metal vapor (i.e., small metal particles generated during the laser pulse induced ablation process) and to avoid contaminating the environment with air containing metal vapor, it has been found that even strong exhaust systems cannot reliably remove metal vapor or particulate metal material from the treatment volume, where the treatment volume means at least the volume surrounding the surface portion of the first metal part being treated with the laser pulse and which is usually contaminated with metal vapor. As a result, metal particles and / or metal ions of the metal vapor may eventually be redeposited on the metal surface that has just been ablated, which causes a reduction in purity on the ablated metal surface and, therefore, a reduction in adhesion of the glue to the re-contaminated metal surface. It has been found that such redeposition, while being desirable for essentially all metal surfaces, becomes particularly troublesome for steel surfaces, which is believed to be due to the chromium content of the steel.

[0019] According to the present disclosure, a pressurized air or gas stream is directed to a surface portion of a first metal part being treated with a laser pulse, for example, to a surface portion in which a surface area is ablated by the laser pulse. Due to the action of the ablative laser pulse, the pressurized air or gas stream tends to carry away metal vapor and particulate metal species ejected into the surrounding environment (i.e., ejected into the treatment volume) from the treated surface portion, which, depending on the pulse length and the energy applied, can be considered to cause sublimation and melting of the surface layer. Due to the sudden sublimation and melting, atoms and particulate matter in the micron and submicron range are ejected into the treatment volume around the surface portion being treated. The gaseous and particulate components can form a plasma that shields the surface portion being treated by the laser pulse, and some of the laser energy can become absorbed by the plasma, and thus the ablation process can become attenuated. In addition, the particulate matter can again impinge on the ablated surface and can then cause re-contamination of the activated metal surface. It was found that recontamination, in general and for first metal parts made of steel, and in particular recontamination containing chromium, causes loosely attached recontamination areas, which can cause breaking points for the glue applied to the ablated surface. It has been determined that applying a pressurized air or gas stream to the treated surface portion can improve the resulting purity of the ablated surface portion considerably, and that the likelihood of metal particles becoming deposited on the ablated metal surface is reduced as metal particles are carried away by the pressurized air or gas stream. The parts that are glued together withstand much higher stresses than parts that are glued together where no pressurized air or gas stream is applied, which is discussed below.

[0020] According to the present disclosure, "air or gas stream" means a conventional air stream or a stream of an inert gas such as nitrogen and / or argon, and a mixture of air and purified inert gas is also contemplated.

[0021] Although in this disclosure the term "adhesive" shall mean all adhesives suitable for metallically bonding a first metal to another component, in particular a second metal component, an example adhesive is DELO DUPOPOX CR8016 available from DELO Industrie Klebstoffe GmbH & Co. KGaA, Windach, Germany.

[0022] In hindsight, applying a stream of pressurized air or gas to the metal surface currently being laser ablated may sound obvious, but understanding the lack of expected adhesion between the components that are ultimately glued together when no pressurized air or gas stream is applied is actually a long process. This is particularly the case because, as described below in Fig. 8A and Figure 8BIn the actual examples further illustrated in , such lack of expected adhesion was shown for only a small portion of the glued metal parts. First, it is generally and generally believed that an exhaust system operating at negative pressure to remove air and therefore also remove any vaporized material and / or small particles present in the processing volume surrounding the processing area provides sufficient performance to clear metal vapor from the processing volume. Second, those skilled in the art have not previously considered a pressurized air or gas stream applied to the surface currently being laser ablated.

[0023] Various parameters of the air or gas flow are studied with respect to the quality of the air flow's ability to carry away metal vapor and / or particulate matter around the surface portion being treated (i.e., from the treatment volume), and thereby reduce recontamination of the just activated metal surface. The air or gas flow parameters studied are as follows: the velocity of the air or gas at the surface portion being treated, the velocity of the air or gas at the outlet of the pressure nozzle, the distance of the pressure nozzle to the surface portion being treated, the amount of air or gas delivered by the pressure nozzle (also referred to as air flow), the shape of the pressure nozzle, and the orientation and / or position of the pressure nozzle relative to the surface portion being treated. These air or gas flow parameters are discussed in more detail below.

[0024] Metal particles formed during laser pulse induced ablation tend to have velocities that extend into the sonic and ultrasonic ranges, where it is understood that the speed of sound in air at 20 degrees Celsius is 343 m / s.

[0025] It has been found that the velocity of the pressurized air or gas stream at the portion of the surface being treated with the laser can result in a more pronounced reduction in recontamination than higher or much lower velocities within the velocity range of the particulate matter in the treatment volume. Velocities of the pressurized air or gas stream at the portion of the surface being treated in the range between 80 m / s and 400 m / s have been found to be effective.

[0026] The pressurized air or gas stream or jet is usually delivered by a pressurized air or gas delivery system (e.g., compressed air or gas reservoir). The pressurized air or gas stream usually leaves the pressurized air or gas delivery system via a pressure nozzle. It is also found that the speed of the pressurized air or gas delivery system at the pressure nozzle can be in the range between 100m / s and 700m / s. The pressurized air or gas can have a compression in the range between 1 bar and 6 bars (these values ​​mean compression higher than atmospheric pressure), wherein the compression can preferably be in the range between 2 bars and 5 bars. The pressurized air or gas stream can be directed toward the surface portion of the first metal part being processed with the laser pulse. It is found that the pressure nozzle with such an outlet shape (i.e., the shape of the air or gas outlet) tends to cause improved adhesion results, and the outlet shape makes the pressurized air or gas stream impacting on the surface portion being processed have a roughly cross-sectional shape that follows the shape of the surface portion. It is believed that this can be attributed to the more constant static pressure of the pressurized air or gas stream on the surface portion being processed. Specifically, the static pressure of the pressurized air or gas stream over at least 50% of the surface portion is no more than about ± 20%, preferably no more than about ± 15% of the average static pressure value in the at least 50% of the surface portion. The surface portion being processed may be particularly related to the length of the laser pulse line. It can be assumed that the surface portion being processed has a specific area that can be covered by adjacent or slightly overlapping laser pulses. For example, a single laser pulse can be circular and can have a diameter of 50 μm and a pulse length in the nanosecond to femtosecond range. Pulses can be applied at a frequency of 400kHz. The pulses along the laser pulse line can then have a center-to-center distance of 20 μm. Therefore, a pulse line with a length of 10 mm can be applied in 1 / 800 seconds. This means that an area of ​​1.6 mm2 can be processed in one second (ignoring any time required to turn the laser beam, which is usually completed by a reflector). This means that the surface area being processed has a length extension defined by the length of the laser line. As mentioned, it seems beneficial to use a pressurized air or gas stream covering the entire length of the laser line. The pressurized air or gas stream may also cover the width of the total surface portion to be treated, but in order to limit the need for pressurized air or gas, the width of the pressurized air or gas stream may also be limited and then the pressurized air or gas stream may be arranged to follow the laser in the width direction, or the first metal component may be moved to keep the surface portion currently being treated inside the cross-section of the pressurized air or gas stream. In the case where the first metal component has a total surface portion to be treated that extends circumferentially around the first metal component, the first metal component may be rotated so that the surface portion currently being treated remains within the cross-section of the pressurized air or gas stream.The width of the pressurized air or gas flow can then be selected to be greater than the width of the rotating first metal component so that the pressurized air or gas flow can carry metal vapor and particulate matter around the first metal component, wherein the pressurized air or gas flow together with the carried metal vapor and particulate matter are ultimately discharged by the exhaust system.

[0027] It has been found to be sensible to place the pressure nozzle with the air or gas outlet at a distance from the surface portion being treated in the range between 4 mm and 20 mm, preferably in the range between 8 mm and 16 mm, wherein the distance is measured between the center point of the air or gas outlet and the center point of the surface portion. It may be sensible to try to place the pressure nozzle as close as possible to the first metal part, since the longer the distance, the smaller the speed of the pressurized air or gas stream. The pressure nozzle must not be placed in the laser path, but may be placed at any side relative to the surface portion being treated, wherein it may be preferably placed below or above the surface portion being treated, wherein below or above shall mean relative to the laser pulse line applied to the surface portion.

[0028] In case the total surface area to be treated with the laser pulses is curved, for example if the total surface area is a surface of a metal shaft extending circumferentially around the shaft, the laser may be moved around the first metal part or the first metal part may be moved (e.g. rotated). This implies that the pressurized air or gas stream does not need to cover the complete total surface area intended to be treated with the laser pulses, but it is sufficient to impinge the pressurized air or gas stream on the surface portion currently being treated. This means that in case the surface portion currently being treated is longer in one direction than in a vertical direction, the nozzle may have a substantially elliptical or substantially elongated shape, wherein the long axis of the elliptical or elongated shape may coincide with the longer extension of the surface portion currently being treated.

[0029] The exhaust system (e.g. a double horn exhaust system enclosing a treatment area) may have a suction power in the range between 500 l / min and 3000 l / min, i.e. a suction power that is higher and even significantly higher than the air flow provided by a pressurized air or gas flow.

[0030] In a practical example, the first metal component is a steel shaft of a personal care device, and the other component is a second metal component, namely a metal cap. The steel shaft can be treated by laser pulses over a total surface area that can extend circumferentially around the steel shaft. In addition to laser pretreatment, the first metal component can generally be pretreated first by another method (such as plasma pretreatment) to fix volatile organic compounds on the surface of the metal component. In particular, the turned and polished metal shaft can still contain volatile organic compounds on its surface, and the fixation of these volatile organic compounds before the activation of the metal surface by laser ablation supports keeping the activated surface portion free from contamination. This of course applies to all first metal components that are independent of the realization of the steel shaft. The steel shaft can be made of standard stainless steel and can therefore contain a certain percentage of chromium, for example, more than 10.5% by weight. The metal cap can also be made of standard stainless steel, specifically in a deep drawing process as is known in the art. Although the inner surface portion of the metal cap can also be pretreated before gluing (for example, by plasma pretreatment and / or by laser pretreatment), this should not be considered mandatory. As described in relation to Figure 8B As exemplified in the description of , a metal cap is glued to the end of a steel shaft and the metal cap may house additional components, such as a permanent magnet.

[0031] In general, for details on the metal bonding process including femtosecond laser pulse pretreatment and optional plasma pretreatment, reference is made to EP 3 792 323 A1, which is hereby incorporated by reference.

[0032] Table 1 below lists the relevant values ​​for ultrafast laser pulse preconditioning as an example and provides some ranges that are considered sensible, although the table below should not exclude values ​​outside the proposed ranges from being used. In general, these values ​​can be varied to some extent while the light fluence remains within the proposed ranges. It is to be reiterated that the application of pressurized air or gas flow proposed herein is also sensible for longer or even shorter laser pulse lengths.

[0033] Example Value The proposed scope Laser wavelength 1030nm 930nm–1064nm Laser pulse length 900fs 1fs–990fs Laser frequency 400kHz 100kHz–1MHz Laser spot diameter 50μm 30μm–80μm Laser pulse energy 50μJ 30μJ–80μJ Light fluence <![CDATA[≈6.6J / cm 2 ]]> <![CDATA[5.0J / cm 2 –8.0J / cm 2 ]]> Laser feed speed 8,000mm / s 1,000mm / s–20,000mm / s

[0034] Table 1: Example values ​​and proposed ranges for ultrafast laser pulse pretreatment of metal surfaces. Adjust the values ​​so that the light fluence remains within the proposed range. .

[0035] A qualitative test method was developed to investigate the strength of an adhesive connection between a first metal component and another component, and in particular for testing the strength of an adhesive connection between a steel shaft and a metal cap. In this test method, a hammer is pivotally mounted at the end of its shaft, and the hammer is deflected until a predetermined stop has been reached, and then the hammer is released, becomes accelerated by gravity, and strikes the metal cap / steel shaft element. Between each stroke, the metal cap / steel shaft element rotates about its longitudinal axis by about 20 to 30 degrees. Metal cap / steel shaft elements made with the method but without an additionally applied pressurized air or gas flow withstand up to about 110 hammer strokes from a sample size of 30, and those made with an applied pressurized air or gas flow withstand at least about 200 hammer strokes from a sample size of 30. It was also found in these hammer tests that for the metal cap / steel shaft elements made without a pressurized air or gas flow, breakage generally occurred at the boundary between the adhesive and the steel, i.e., once the metal cap could be separated from the steel shaft by manual force, there was essentially no adhesive residue attached to the steel shaft. In contrast, for the metal cap / steel shaft elements made with a pressurized air or gas flow, breakage generally occurred within the adhesive, i.e., once the metal cap could be separated from the steel shaft by manual force, adhesive residue remained on the steel shaft. This indicates that the surface adhesion between the adhesive and the steel surface is considerably improved when a pressurized air or gas flow is applied in the manufacturing process.

[0036] Figure 1 1 is a depiction of a first exemplary apparatus 1 for pre-treating a surface portion 110 of a first metal component 100 with laser pulses, preferably with a pulse length in the nanosecond, picosecond or femtosecond range. The arrow indicates the path 10 of the laser beam applied to the surface portion 110 in operation. An exhaust system 200 comprising a double horn structure with a first suction horn 210 and a second suction horn 220 is arranged to exhaust air and / or gas and / or any vapor or particulate matter from a treatment volume 190 surrounding the first metal component 100. The first metal component 100 is here shaft-shaped and can be a steel shaft. Although this is not particularly useful for Figure 1 10 is not relevant to the explanation of the invention, but here the first metal component 100 extends from a complete internal motor infrastructure that is intended to be inserted into the housing of the personal care device after another component (i.e., the metal cap) has been glued to the steel shaft. The pressure nozzle section 301 of the pressurized air or gas delivery system 300 is arranged outside the path 10 of the laser pulses and directs a pressurized air or gas stream (see FIG. 10 ) via a pressure nozzle 310 having an air or gas outlet 311. Figure 3) is directed onto the surface portion 110 of the first metal component 100 being treated with the laser pulses in operation. An air or gas outlet 311 is provided so that the pressurized air or gas flow is directed onto the surface portion 110 being treated. More precisely, as in the example shown, the total surface area to be treated with the laser pulses extends circumferentially around the first metal component 100, and the pressurized air or gas flow is directed onto the surface portion 110 currently being treated with the laser pulses, i.e. the surface portion 110 where the metal vapor and particulate matter are being ejected into the treatment volume 190. The first metal component 100 may be arranged to be movable, for example, to be rotatable around its longitudinal axis during treatment, so that the laser can then treat all areas of the total surface portion to be treated. The laser beam may also be arranged to have a moving laser beam, wherein the laser spot on the first metal component 100 can be moved in an up-and-down manner, whereby the laser spot can describe an hourglass-shaped path on the surface portion, so that the rotation of the first metal component 100 is compensated and the laser moves along the first metal component 100 in a parallel line. As an alternative or in addition to the rotation, the first metal component 100 can also be moved linearly.

[0037] Figure 2 1A is a cross-sectional section through another example apparatus 1A for pre-treating a surface portion 110A of a first metal component 100A with a laser pulse. An exhaust system 200A comprising a dual horn structure having a first suction horn 210A and a second suction horn 220A is arranged to exhaust air and / or gas and / or any vapor or particulate matter from a treatment volume 190A surrounding the first metal component 100A. A pressurized air or gas delivery system 300A is integrated into the exhaust system 200A, specifically into the first suction horn 210A. A pressure nozzle 310A having an air or gas outlet 311A ​​is arranged to provide a pressurized air or gas flow directed onto a surface portion 110A of the first metal component 100A. A cutout 211A is provided in the first suction horn 210A to provide a free path area for the laser beam to irradiate the surface portion 110A. The pressurized air or gas delivery system 300A (here only the nozzle portion is shown) may be and is at least partially integrated with the first suction horn 210A, or may be a separate component that may be fitted into the first suction horn 210A, for example.

[0038] Figure 3 is a depiction of a simulation applying a pressurized air or gas stream 320B emitted from a pressure nozzle 310B, where the density of dots indicates the velocity of the air or gas particles. Figure 3A two-dimensional section showing a simulated velocity profile through a pressurized air or gas flow 320B which here centrally impinges on a rotationally symmetric first metal component 100B, which here may be a steel shaft rotationally symmetric about a longitudinal axis L. Figure 3 It is presented here as an example of a simulation showing promising results for the quality of pressurized air and gas flows.

[0039] Figure 4 Is to indicate Figure 3 The static pressure P on the surface of the first metal component is shown S The two graphs 401 and 402 depict the reference Figure 3 , along a line from the bottom to the end of the surface portion of the first metal component to simulate the static pressure. Graphs 401 and 402 indicate the static pressure along the line from the bottom to the end of the surface portion of the first metal component. Figure 3 The static pressure of the line of the cross-sectional section shown. Figure 4 It can be seen in FIG. 1 that if the outlet opening of the pressure nozzle is elongated or elliptical so that the cross-sectional shape of the pressurized air or gas stream roughly corresponds to the shape and in particular the length extension of the surface portion currently being treated with the laser pulse, the static pressure P S is relatively uniform over a larger portion of the surface portion being treated. On the one hand, this serves to direct the pressurized air or gas flow only onto the surface portion being treated, rather than directing the pressurized air or gas flow into areas on the sides where energy would be lost without causing impact. On the other hand, this serves to avoid re-contamination due to air or gas flow from an area experiencing high static pressure into an area experiencing low static pressure. Graph 420 relates to a circular pressure nozzle that is sized so that the pressurized air or gas flow does not extend beyond the first metal part in a direction perpendicular to the line along which the simulated static pressure is located. The hammer test described above shows that when the pressurized air or gas flow causes a static pressure P as indicated by graph 410, the pressure at which the pressurized air or gas flow is caused ... S The adhesive connection withstands more hammer strokes.

[0040] Figure 5A is a SEM picture (where SEM stands for scanning electron microscope) of a metal component surface (specifically a steel shaft surface) which has been treated with a femtosecond laser to ablate the top layer, without applying a pressurized air or gas flow. A scale indicating 500 nm is shown. Various structures can be seen that are believed to be related to recontamination by particulate matter formed during the ablation process. As already described, it is believed that such recontamination (specifically caused by metal particles (such as chromium) that are not strongly attached to the activated metal component surface) causes breaking points for the adhesive connection made with the adhesive.

[0041] Figure 5B is a SEM picture related to the same scale of 500 nm of a similar metal component surface, also from a steel shaft, which has been treated with a femtosecond laser to ablate the top layer, wherein a pressurized air or gas flow is applied during the application of the laser pulses. Figure 5A As can be seen in the graph, the metal surface shows less structure associated with re-contamination of the metal surface by particulate matter and evaporated surface material. As explained previously, the application of a pressurized air or gas stream causes a surprising effect in a manner that appears to reduce re-contamination of the ablated metal surface. The effect on the adhesion of the glue causes the improvement as described above, i.e. causes a much better adhesion to the metal surface connection.

[0042] It is believed that the effect of the pressurized air or gas flow will also exist for other laser pulse lengths higher than femtosecond laser pulses, for example, for picosecond or nanosecond laser pulses and for attosecond laser pulses.

[0043] Fig. 6A is a photograph of a steel metal shaft that has been treated with femtosecond laser pulses without the application of pressurized air or gas flow and has been glued to a metal cap and where the adhesive connection has been tested by hammering as described above. It can be seen that essentially no macroscopic adhesive residue is left on the metal surface. In contrast, Figure 6B Shown with Fig. 6A Photograph of a substantially identical steel shaft shown which has also been treated with a femtosecond laser while applying a pressurized air or gas stream as proposed herein. The steel shaft was glued into a metal cap and the adhesive connection was subsequently tested with a hammering method. A number of adhesive residues remained on the steel shaft. The latter is believed to be evidence for the following: the presence of breakage points on the steel shaft surface due to recontamination is effectively reduced and the hammering method destroys the adhesive but does not cause loosening of the adhesive connection between the adhesive and the metal surface.

[0044] Figure 7 A perspective view onto an example nozzle section 301C of a pressurized air or gas delivery system is shown. The viewing direction is generally from the Figure 1 and Figure 2The pre-treatment device shown in the example starts at the center point on the surface portion being processed on the first metal part. Nozzle section 301C includes a pressure nozzle 310C with an elongated air or gas outlet 311C. It can also be seen that the pressure nozzle 310C is connected to a substantially circular delivery orifice 312C, and the pressure nozzle 311C provides a transition in the elongated cross section from the circular cross section to the front of the pressure nozzle 310C, wherein the cross section widens in the length direction and narrows to a certain extent in the width direction. The cross-sectional shape of the front of the pressure nozzle 310C can be described as a rhombus shape (that is, a rectangle with two semicircles at the small end of the rectangle) here. The air or gas outlet 311C is shaped so that the pressurized air or gas stream covers the entire length of the surface portion to be processed by the laser pulse.

[0045] Fig. 8A 5 is a depiction of an example personal care device 50, which is implemented as an electric toothbrush having a handle portion 51 and a treatment head 52 (here implemented as a replaceable brush head). In the example shown, the treatment head 52 includes a functional head 53, which can be driven to perform an oscillating rotational movement relative to the housing of the treatment head 52.

[0046] Figure 8B yes Fig. 8A An enlarged view of a portion of the personal care device 50 shown, wherein the enlarged portion is shown in a partially cut open state, so that the coupling between the drive shaft 510 of the handle portion 51 and the motion transmitter 520 of the treatment head 52 can be seen. The drive shaft 510 is driven into a linear reciprocating motion V in operation, which is transmitted to the functional head 53 of the treatment head 52 via the motion transmitter 520, wherein the linear reciprocating motion is transmitted to the oscillating rotation of the functional head 53. The drive shaft 510 can be a steel shaft that has been glued to the metal cap 511. According to the present disclosure, at least a portion of the outer surface of the steel shaft is treated with a laser pulse while applying a pressurized air or gas flow. At least a portion of the inner surface of the metal cap may also have been treated with a laser pulse, although this is not mandatory. Specific to the example shown, a permanent magnet 512 is placed in the metal cap 511, and an adhesive 513 fills the inner hollow portion of the metal cap 511. The permanent magnet 512 is coupled to a magnetizable steel element 521, for example, arranged at the opposite end of the motion transmitter 520. The adhesive connection formed by the described gluing method allows the steel shaft 510 and the metal cap 511 to be durably connected even under cyclic loads acting on the metal cap due to the linear reciprocating motion V and also in an aggressive environment formed by toothpaste and saliva. It should be understood that Fig. 8A and Figure 8B The examples shown do not limit the scope of the present disclosure.

[0047] The dimensions and values ​​disclosed herein should not be understood as being strictly limited to the exact numerical values ​​cited. Instead, unless otherwise indicated, each such dimension is intended to represent the stated value and a functionally equivalent range around that value. For example, a dimension disclosed as "40 mm" is intended to mean "about 40 mm".

Claims

1. A method of gluing a first metal component to another component, the method comprising: The following steps are involved: - providing a first metal component such as a steel shaft and another component such as a second metal component; - treating a surface portion of said first metal component intended for gluing to said further component with laser pulses so as to remove a surface layer of said first metal component across said surface portion, preferably by ablation; - while applying the laser pulses to said surface portion of said first metal component, also applying a pressurized air or gas flow to said surface portion; - applying an adhesive to at least said surface portion of said first metal component and / or to a surface of said further component; as well as - gluing the first metal component and the further component together.

2. The method according to claim 1, wherein the pressurized air or gas flow has a velocity at the surface portion in the range between 80 m / s and 400 m / s.

3. The method according to claim 1 or 2, wherein the air or gas flow rate of the pressurized air or gas flow is in the range between 50 l / min and 400 l / min.

4. The method according to one of claims 1 to 3, wherein the angle between the center line of the pressurized air or gas stream and the center line of the laser pulses is in the range between 10 and 35 degrees.

5. The method according to one of claims 1 to 4, wherein the static pressure of the pressurized air or gas flow over at least 50% of the surface portion deviates from the average static pressure value in the at least 50% of the surface portion by no more than about ±20%.

6. A method according to one of claims 1 to 5, wherein the pressurized air or gas flow is provided by a pressure nozzle having an air or gas outlet having a distance from the surface portion in a range between 4 mm and 20 mm, preferably in a range between 8 mm and 16 mm, wherein the distance is measured between a center point of the air or gas outlet and a center point of the surface portion.

7. The method of claim 6, wherein the pressure nozzle has a shape such that a cross-sectional shape of the pressurized air or gas stream impinging on the surface portion of the first metal component substantially follows the shape of the surface portion.

8. A method according to claim 6 or claim 7, wherein the velocity of the pressurized air or gas stream at the air or gas outlet of the pressure nozzle is in the range between 100 m / s and 700 m / s.

9. The method according to one of claims 6 to 8, wherein the pressurized air or gas flow is delivered from a compressed air or gas reservoir or an air or gas compressor, wherein the air or gas is compressed in the range between 1 bar and 6 bar, preferably in the range between 2 bar and 5 bar.

10. The method according to claim 1, wherein The following steps are involved: Air and / or gas is exhausted from the treatment volume at an exhaust rate of between 500 l / min and 3000 l / min.

11. The method according to claim 1, wherein The following steps are involved: The first metal component is rotated about a longitudinally extending axis and wherein the total surface portion intended for gluing to the further component extends circumferentially around the first metal component.

12. The method according to one of claims 1 to 11, wherein the laser pulses have a pulse length in the nanosecond to femtosecond range.

13. A method of manufacturing a personal care device comprising the step of gluing a steel shaft into a metal cap, the method The following steps are involved: - providing the steel shaft and the metal cap, the metal cap being dimensioned to receive at least an end region of the steel shaft; - treating a surface portion of the steel shaft intended for gluing to the metal cap with laser pulses such that a surface layer from the steel shaft across the surface portion is removed, preferably by ablation; - while treating said surface portion of said steel shaft with said laser pulses, also applying a pressurized air or gas stream to said surface portion; - treating with laser pulses at least a portion of the inner surface of the metal cap intended for gluing to a corresponding surface portion of the steel shaft; - applying adhesive to said surface portion of said steel shaft and / or to said portion of said inner surface of said metal cap; as well as - Fitting the metal cap onto the steel shaft and allowing the adhesive to cure.

14. The method according to claim 13, wherein the pressurized air or gas flow has a velocity at the surface portion in the range between 80 m / s and 400 m / s.

15. A method according to claim 13 or claim 14, wherein a pressure nozzle delivering the pressurized air or gas stream has a shape such that the cross-sectional shape of the pressurized air or gas stream impinging on the surface portion of the first metal component generally follows the shape of the surface portion.

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