Personal care device and method of manufacturing such personal care device

Abstract

The present invention relates to a personal care device, such as an electric hair cutter, such as a shaver or toothbrush, and to a method of manufacturing such a personal care device. More specifically, the personal care device includes a handle and a functional head supporting at least one personal care implement, the functional head being attached to the handle, where at least one of the handle and the functional head includes an outer metal housing formed as a unitary piece having a uniform, unitary, seamless structure, the structure has an annular or sleeve-like shape with a closed annular cross-section. The outer metal shell includes at least one undercut portion formed using a hydroforming step that applies a hydraulic pressure to one side of a metal shell blank positioned in a mold to deform the metal shell blank to form the outer metal shell, the outer metal shell including at least one undercut portion, the at least one undercut portion being formed using a hydroforming step that applies a hydraulic pressure to one side of the metal shell blank positioned in the mold. And the opposite sides of the metal shell blank are pressed against the mold so as to adopt the contour of the mold.

Description

Technical Field

[0001] The present invention relates to a personal care device and to a method for manufacturing such a personal care device. More specifically, the present invention relates to a personal care device such as a hair cutter or a toothbrush having an outer metal shell, the personal care device comprising a handle and a functional head attached to the handle, such as a cutter head or a brush head, wherein at least one of the handle and the functional head comprises the outer metal shell, which may be part of a housing for accommodating functional components, such as electronic devices, an electric drive unit including a motor and a mechanical transmitter, or a power supply or storage component (such as a battery). The personal care device may also include a base station for loading and / or cleaning and / or parking a handheld device, wherein the base station may also include such an outer metal shell, which may be part of a housing for accommodating functional components, such as electronic devices, a power supply or a cleaning tool, etc. Background Art

[0002] Handheld personal care devices can affect various personal care functions, such as hair cutting, shaving, skin care, brushing and cleaning, nail trimming or other personal care treatments. Typically, the handle of such a personal care device has a dual function, wherein, on the one hand, the handle is a gripping portion for grasping and holding the personal care device by hand, and on the other hand, the handle accommodates or supports functional components, such as an electric drive unit for driving a personal care tool, such as a hair cutting tool, a brush unit, a skin exfoliation or massage tool, a nail polishing tool or other personal care tools. More specifically, the handle can form a housing in which an electric motor and a mechanical transmitter for transmitting the driving motion of the electric motor to the personal care tool can be accommodated, and in addition, electronic control equipment and power equipment, such as batteries, network power supply terminals and information equipment, such as displays, can also be accommodated. The handle can be waterproof and / or sealed against moisture and / or dust to protect the functional components accommodated in the housing.

[0003] The functional head of such a personal care device typically supports a personal care tool or multiple personal care tools, such as a shear-type foil cutter, a long hair cutter and a trimmer, or one or more brush units, an interdental cleaner, etc., wherein these personal care tools can be movably supported relative to a frame or housing of the functional head, wherein a mechanical transmitter can connect the movably supported tool to a drive unit in the handle.

[0004] The base station can receive or be connected to a handheld personal care device for loading and / or cleaning and / or parking the handheld device, wherein the housing of the base station typically houses functional components, such as electronic devices such as a data processor and a display for communicating with the handheld device, a power source with an electrical connector for charging the handheld device, or a cleaning tool such as a scrubber for cleaning the functional head of the handheld device.

[0005] Typically, the outer housings of the handle, the function head and the base station are mainly made of plastic, wherein a plurality of plastic parts such as a hard plastic part and a soft plastic part may be mounted to each other to form the outer housing.

[0006] On the other hand, the handle and / or the functional head may include an outer metal shell that may form the outer surface of the handle for gripping with the hand or fingers and / or may form at least a portion of the housing for housing the functional components and / or may form a frame for the personal care tool for supporting the functional head. When forming the outer surface of the handle and / or the functional head, such a metal shell may provide a cool touch to the user and have high strength, rigidity, and high resistance to wear, scratching, and chemical environments. In addition, the outer metal shell provides a valuable aesthetic appearance and a clean appearance.

[0007] When mounting functional components in and / or onto such outer metal housings, it is difficult to allow easy and accurate manufacturing of the metal housing on the one hand and easy assembly of the personal care device, including mounting of the functional components, on the other hand, especially when the outer metal housing has a close fit and small size, although the functional components are to be accommodated within the metal housing. Furthermore, openings and perforations in the metal housing for inserting functional components or accessing functional components such as displays, controls or switches or connectors such as stowage cable terminals may have sharp and burred edges.

[0008] Meeting this diverse need becomes even more difficult when the outer shell should have a hollow shape and be made of an integral, uniform, seamless structure. This one-piece structure without visible seams (such as welds between different shell parts) is not only ideal from an aesthetic point of view, but also increases strength and rigidity and reduces installation steps. However, this one-piece structure with a hollow ring-like or sleeve-like shape requires at least one opening through which the above-mentioned functional components such as electronic devices, drive units or batteries or mechanical transmitters can be inserted, or the internal components can be accessed through the opening. Providing a large opening facilitates the installation process, but reduces strength, while a small opening does not allow easy installation. In any case, it is difficult to achieve a close fit between the metal shell and the functional components without compromising the ergonomic shape and the aesthetic three-dimensional complex appearance.

[0009] Furthermore, it is revealed that the edges of the metal casing may create edges that injure the user's skin. Summary of the invention

[0010] It is an object of the present invention to provide an improved personal care device which avoids at least one disadvantage of the prior art and / or further develops existing solutions.It is another object of the present invention to provide an improved method of manufacturing such a personal care device comprising an outer metal casing and / or a metal housing.

[0011] Another object of the present invention is to provide a metal housing or outer metal shell and a method for manufacturing the same without hurting the user's skin at the edge of the metal housing or metal shell.

[0012] Another object of the present invention is to provide an improved outer metal shell for such a personal care device, which outer metal shell combines a small footprint and a close fit with functional components mounted in and / or on the metal shell, and is easy to install the functional components without sacrificing the functional shape of the outer metal shell, thereby providing rigidity and ergonomic grip.

[0013] Another object of the present invention is to provide an improved method for manufacturing an outer metal shell for a personal care device, which allows precise forming of the metal shell even if the metal shell has a complex three-dimensional shape without requiring a large number of processing steps using complex and expensive tools.

[0014] To achieve at least one of the above objects, a personal care device is provided comprising the features of claim 1. To achieve at least one of the above objects, a method of manufacturing a personal care device is provided comprising the features of claim 18. Further advantageous aspects consist of the features of the subclaims.

[0015] Preferably, a personal care device such as a hair cutter or a toothbrush is provided, the personal care device comprising a handle and a functional head supporting at least one personal care tool, the functional head being attached to the handle, wherein at least one of the handle and the functional head comprises an outer metal shell, the metal shell having at least one opening, wherein at least one plastic base structural member is accommodated within the outer metal shell, the plastic base structural member having a protrusion that passes through the opening in the outer metal shell and protrudes beyond the outer surface of the metal shell section surrounding the opening, and / or the plastic base structural member completely covers the outer edge of the opening. Therefore, it is not necessary to add a further manufacturing step to round the edges at the openings of the outer shell, because these edges are completely covered by the modules or plastic base structural components installed in these openings and thus cover the edges. Preferably, the installed modules or plastic base structural components are arranged as a kind of skin buffer or skin protector, protruding beyond the outer surface of the outer shell and / or protruding beyond the top end of the outer shell.

[0016] More preferably, the outer metal shell comprises at least one lateral opening, through which a functional component extending at least partially to the outside of the outer metal shell and / or accessible from the outside of the outer metal shell is connected to another functional component accommodated inside the outer metal shell. Thus, the lateral opening in the metal shell accommodates a functional component or a plastic infrastructure component therein.

[0017] More preferably, the handle is provided with a front module and a rear module at opposite lateral sides thereof, each module being provided with said plastic base structural member extending through a corresponding opening of said outer metal shell.

[0018] More preferably, the handle is provided with a top module and a bottom module at opposite longitudinal sides thereof, each module being provided with said plastic base structural member extending through a corresponding opening of said outer metal shell.

[0019] More preferably, the functional head is provided with the plastic base structural member extending through the bottom opening and the top opening of the functional head.

[0020] More preferably, the protrusion comprises a collar overlapping the opening and / or seating on the outer surface of the metal housing section surrounding the opening.

[0021] More preferably, the protrusion protrudes beyond the outer surface of the metal shell by a certain amount, which is substantially constant along the entire opening even when the contour of the opening does not extend in one plane; and / or protrudes beyond an amount in the range of 0.05mm to 1mm or 0.1mm to 0.5mm or 0.1mm to 0.3mm.

[0022] More preferably, the protrusion is made of soft plastic and / or hard plastic, and the outer contour of the protrusion matches the inner contour of the opening in terms of shape and size to provide sealing and / or form-fitting and / or snap-fitting engagement of the protrusion with the metal housing.

[0023] More preferably, the metal shell has opposite end portions, each end portion defining a closed annular cross-section, wherein an intermediate section between the opposite end portions includes at least one lateral opening and / or lateral perforation for accessing at least one functional component housed inside the outer metal shell.

[0024] More preferably, the outer metal shell forms a unitary piece having a unitary, uniform, seamless structure having a ring-like or sleeve-like shape with a closed annular cross-section.

[0025] More preferably, the outer metal shell is a hydroformed part and / or a water pressure formed part by hydraulic deformation.

[0026] More preferably, the outer metal shell comprises at least one undercut portion.

[0027] More preferably, the outer metal shell includes a raised middle section defining a maximum cross-sectional area and a pair of opposite end portions provided with front openings, the pair of opposite end portions having a cross-sectional area smaller than the maximum cross-sectional area of ​​the raised middle section.

[0028] More preferably, the outer metal shell includes at least one opening surrounded by a three-dimensionally shaped metal shell segment, the opening having a three-dimensionally shaped edge profile extending substantially perpendicularly to the surrounding metal shell segment along the entire profile of the opening, and the surrounding shell portion adjacent to and surrounding the opening having a variable orientation along the opening.

[0029] More preferably, the metal shell has opposite end portions, each end portion defining a closed annular cross-section, wherein an intermediate section between the opposite end portions includes at least one lateral opening and / or lateral perforation for accessing at least one functional component housed inside the outer metal shell.

[0030] More preferably, the outer metal shell has an elongated hollow shape having front openings at opposite axial end portions, the axial end portions having closed annular cross-sections surrounding the openings.

[0031] More preferably, the metal shell is made of stainless steel or a steel containing chromium, nickel and molybdenum, in particular 10 to 25 mass% Cr, 5 to 20 mass% Ni and 1 to 5 mass% Mo or 16 to 18 mass% Cr, 10 to 14 mass% Ni and 2 to 3 mass% Mo.

[0032] A method of manufacturing a handheld personal care device such as a hair cutter or toothbrush having an outer metal housing, the method comprising the steps of:

[0033] forming the outer metal housing into a desired shape, and

[0034] installing a functional component for performing or assisting in performing a personal care function into and / or onto the formed outer metal shell, wherein the forming step includes a hydroforming step of applying hydraulic pressure to one side of a metal shell blank positioned in a die to deform the metal shell blank and press an opposite side of the metal shell blank against the die to adopt a contour of the die, thereby forming an outer metal shell having a desired shape,

[0035] providing a cutting step for forming at least one opening in the outer metal shell, and

[0036] A plastic base structure part is mounted in the at least one opening and wherein an outer edge of the opening is covered by the plastic base structure part and / or the plastic base structure part protrudes beyond the outer metal shell.

[0037] More preferably, the metal shell blank has a hollow, sleeve-like or tubular shape and is positioned in the cavity of the mold surrounding the outside of the metal shell blank, wherein hydraulic pressure is applied to the inside of the hollow metal shell blank to expand the hollow metal shell blank and press the outside of the metal shell blank against the contour of the cavity of the mold so that the outside of the metal shell blank adopts the contour of the mold.

[0038] More preferably, one or more undercut portions of said outer metal shell are hydroformed during said hydroforming step.

[0039] It is suggested that the outer metal shell be formed as an integral piece with a uniform, integral and seamless structure, which has an annular or sleeve-like shape with an annular closed cross section, and the outer metal shell is provided with one or more undercuts. Combining this seamless one-piece annular structure with one or more undercuts not only provides excellent strength and rigidity, but also allows a close fit and small size of the metal shell despite the installation of one or more functional components in and / or on the metal shell, because the shape of the metal shell can be adapted to match the contours of these functional components of the personal care device. For example, one or more undercut portions of the metal shell can provide additional accommodation space for bulky parts of the functional components without increasing the size of the entire length of the metal shell. At the same time, ergonomic requirements can be met by the organic shape of the part that is grasped by hand or in contact with the skin. In addition, the precious aesthetic appearance can be combined with a cool touch for the user. Due to the seamless one-piece structure, the accumulation of dirt is avoided, and irritation to the skin due to scratched edges can be reduced. The one-piece integral structure of the outer shell refers to a separate handle or functional head. The functional head is connected to the handle by a supporting structure, which allows the mobility of the head relative to the handle, thereby providing two outer shells for each of the head and the handle, and at least one of the head and the handle includes the above-mentioned metal shell. Alternatively, both the head and the handle are provided with such a separate metal outer shell. In addition, the functional head and the handle are provided with a metal outer shell structure as described above. If the head outer shell is immovable relative to the handle outer shell, the latter variant is particularly suitable.

[0040] To combine design freedom allowing complex shapes with efficient forming of the shell, the outer metal shell may be formed at least in part by hydraulic pressure that deforms the metal shell into a desired shape. According to one aspect, the outer metal shell includes at least one hydroformed portion.

[0041] More specifically, the above-mentioned one or more undercuts of the outer metal shell are formed by hydraulic pressure applied to the shell portion that is desired to have such an undercut structure, wherein the outer metal shell can still be formed as a unitary piece with a uniform, integral and seamless structure, which has a closed ring-like or closed sleeve-like shape.

[0042] For example, a substantially tubular, elongated outer metal shell of a handle or a hollow, sleeve-like outer shell of a functional head of a personal care device, or another hollow outer metal shell of a personal care device accessory such as a loading station, can have a hydraulically formed profile having a middle section defining a maximum cross-sectional area and a pair of end portions arranged on opposite sides of the middle shell section and having a smaller cross-sectional area than the raised middle section.

[0043] More specifically, forming the outer metal shell includes a hydroforming step that applies hydraulic pressure to one side of a metal shell blank positioned in a die to deform the metal shell blank and press the opposite side of the metal shell blank against the die to adopt the contour of the die, thereby forming the outer metal shell having a desired shape. This hydroforming step allows the metal shell blank to be deformed into a complex three-dimensional shape without the problem of removing a mechanical forming tool such as a punch, a push rod or a movable core element from a recess of the metal shell.

[0044] The hydroforming step may be a water forming step, wherein the metal shell blank in the die and / or the die is filled with a hydraulic fluid such as water or oil, wherein pressure is applied to the hydraulic fluid from a pressure source external to the die.

[0045] These and other advantages become apparent from the following description with reference to the accompanying drawings and possible examples. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 : A front view of a personal care device in the case of an electric shaver, the personal care device comprising: a handle comprising an outer metal housing; and a functional head in the case of a razor head, the functional head comprising a metal housing supporting a hair cutting tool including a shear foil cutter and a long hair cutter,

[0047] Figure 2 : Figure 1 A partially exploded side view of a personal care device of FIG. 1 showing the front and rear modules removed from the outer metal housing of the handle,

[0048] Figure 3 : Similar to Figure 2 An exploded side view of a personal care device of claim 1, showing an assembly of functional components received within an outer metal housing of a handle,

[0049] Figure 4 : Similar to Figure 3 Partially exploded side views of a personal care device of the type shown, wherein partial view (a) shows the functional component assembly to be received within the outer metal housing of the handle and the functional head in terms of the razor head attached thereto, partial view (b) shows the functional component assembly received within the outer metal core to which the functional head is attached, wherein the front and rear modules are shown removed from the front and rear sides of the outer metal core,

[0050] Figure 5 : Similar to Figure 4Exploded side views of a personal care device, wherein partial view (a) shows a functional element assembly without an outer metal shell, wherein a functional head and a bottom module connectable to the functional element assembly are shown in a position removed from the functional element assembly, wherein partial view (b) shows the functional element assembly received in the outer metal shell, wherein the connectable functional head, bottom module and front and rear modules are removed from the outer metal shell and the functional element assembly,

[0051] Figure 6 : A front view of the outer metal housing of the handle of the personal care device of the aforementioned figure, wherein there is no cutout in the outer metal housing to better illustrate the stretch factor,

[0052] Figure 7 : Similar to Figure 3 partial cross-sectional side views of a personal care device, wherein partial view (a) shows an outer metal shell in which a functional element assembly is housed and a front module, a rear module, a bottom module and a head module attached to the outer metal shell, wherein partial view (b) shows an enlarged cross-sectional view of a portion marked "E" of a handle of the personal care device, the enlarged cross-sectional view showing an interface between the outer metal shell and the head module and the front module to illustrate that the front module and the head module have protrusions protruding beyond the outer surface of the outer metal shell,

[0053] Figure 8 : Schematic diagram of the process steps of hydroforming the outer metal shell of the personal care device of the aforementioned figure, wherein partial view (a) shows the insertion of the metal shell blank into an open mold, partial view (b) shows the metal shell blank in the closed mold before the application of hydraulic pressure, partial view (c) shows the tubular metal shell blank filled with hydraulic fluid immediately before hydroforming, partial view (d) shows hydraulic pressure being applied to the interior of the tubular metal shell blank and entering the cavity of the mold, wherein axial compression is applied to the metal shell blank during the application of hydraulic pressure, and partial view (e) shows the removal of the hydroformed metal shell having the desired shape from the open mold,

[0054] Fig. 9 : Side views of a tubular metal shell blank and a formed metal shell at different stages of forming an outer metal shell, respectively, wherein partial view (a) shows an undeformed tubular metal shell blank, partial view (b) shows a deformed metal shell blank after a hydroforming step, the deformed metal shell blank comprising two outer metal shells in their desired shapes, partial view (c) shows cutting the deformed metal shell of step (b) into several parts comprising two metal shells, and partial view (d) shows the obtained two outer metal shells with lateral cuts,

[0055] Fig.10 : Fig. 9cross-sectional views of an outer metal shell of a device, the cross-sectional views illustrating a lateral cut, wherein partial view (a) shows a lateral cut with a sharp edge, and partial view (b) shows a cut with a three-dimensional edge extending perpendicular to the outer surface of the three-dimensionally formed metal shell section surrounding the cut,

[0056] Fig.11 : A cross-sectional view of the functional head of the personal care device of the aforementioned figure, wherein a functional plastic infrastructure including functional elements such as a cutting element and a drive module is received inside an outer metal housing of the functional head,

[0057] Fig.12 : Similar to Fig.11 A cross-sectional view of a functional head showing the interface between the functional infrastructure and the outer metal shell of the functional head,

[0058] Fig.13 : Fig.12 an enlarged cross-sectional view of the area marked “A” of a functional head of FIG. 1 , showing a plastic base structural element having a protrusion that protrudes beyond the outer surface of the outer metal housing of the functional head,

[0059] Fig.14 : A schematic diagram of a machine for forming the outer metal housing of the personal care device of the aforementioned figure by means of electrohydraulic forming, and

[0060] Fig.15 : Schematic diagram of a machine for forming the outer metal shell of the personal care device of the aforementioned figure by means of electromagnetic forming. DETAILED DESCRIPTION

[0061] According to one aspect, it is suggested that the outer metal shell be formed as an integral piece with a uniform, integral and seamless structure, the structure having an annular or sleeve-like shape with an annular closed cross section, the outer metal shell being provided with one or more undercuts. Combining this seamless one-piece annular structure with one or more undercuts not only provides excellent strength and rigidity, but also allows a close fit and small size of the metal shell despite the installation of one or more functional components in and / or on the metal shell, because the shape of the metal shell can be adapted to match the contours of these functional components of the personal care device. For example, one or more undercut portions of the metal shell can provide additional accommodation space for bulky portions of the functional components without increasing the size of the entire length of the metal shell. At the same time, ergonomic requirements can be met by the organic shape of the portion that is grasped by hand or in contact with the skin. In addition, the precious aesthetic appearance can be combined with a cool touch for the user. Due to the seamless one-piece structure, the accumulation of dirt is avoided, and irritation to the skin due to scratched edges can be reduced.

[0062] To combine design freedom allowing complex shapes with efficient forming of the shell, the outer metal shell may be formed at least in part by hydraulic pressure that deforms the metal shell into a desired shape. According to one aspect, the outer metal shell includes at least one hydroformed portion.

[0063] More specifically, the above-mentioned one or more undercuts of the outer metal shell can be a hydroformed portion, wherein the outer metal shell can still be formed as a unitary piece having a uniform, integral and seamless structure having a closed ring-like or closed sleeve-like shape.

[0064] For example, a substantially tubular, elongated outer metal shell of a handle or a hollow, sleeve-like outer shell of a functional head of a personal care device, or another hollow outer metal shell of a personal care device accessory such as a loading station, can have a hydraulically formed profile having a middle section defining a maximum cross-sectional area and a pair of end portions arranged on opposite sides of the middle shell section and having a smaller cross-sectional area than the raised middle section.

[0065] More specifically, forming the outer metal shell may include a hydroforming step that applies hydraulic pressure to one side of a metal shell blank positioned in a die to deform the metal shell blank and press the opposite side of the metal shell blank against the die to adopt the contour of the die, thereby forming the outer metal shell having a desired shape. This hydroforming step allows the metal shell blank to be deformed into a complex three-dimensional shape without the problem of removing a mechanical forming tool such as a punch, a push rod, or a movable core element from a recessed portion of the metal shell.

[0066] For example, the outer metal shell may be hydroformed having a central raised section defining a maximum cross-sectional area and a pair of end portions disposed on opposite sides of the central shell section and having a smaller cross-sectional area than the raised central section.

[0067] Another example of the undercut shape of the outer metal shell may include a substantially hemispherical recess or a bowl-shaped bulb portion closed to the outside of the shell and open to the inside of the shell. In addition, a platform-like protrusion forming the outside, such as a finger grip portion or a support portion for an additional element, may be formed in an undercut manner to be open to the inside of the metal shell.

[0068] As described above, the outer metal shell can have an integral structure. More specifically, the metal shell can be formed as an integral piece with a uniform seamless structure, wherein the outer metal shell can have an annular or sleeve-like shape with a closed annular cross section. However, the annular or sleeve-like outer metal shell can have one or more lateral openings or lateral incisions, wherein there is certainly no closed annular cross section in the region of these incisions. However, the outer metal shell can be formed to have an annular cross section, which has a closed annular shape at least at the opposite end portions of the outer metal shell and / or the opposite sides of the lateral opening. When considering the outer metal shell of the handle of the personal care device, these axial end portions of the outer metal shell can face and support the functional head of the personal care device on the one hand, and can form the bottom end of the handle on the other hand. When considering the functional head, the opposite end portions of the outer metal shell can face the handle on the one hand, and can support the personal care treatment tool and / or can surround or be adjacent to the skin contact surface of the functional head on the other hand.

[0069] Such a closed annular cross section of the end portion can provide rigidity of the housing or frame, in particular provide a solid and rigid support for the functional elements mounted in and on the outer metal shell. However, the axial end side of the metal shell itself can be provided with openings, which can be surrounded by the annular portion with a closed annular cross section. For example, the support structure for supporting the functional head is usually attached to or supported on one of the axial ends of the handle, so providing such an end portion of the outer metal shell with a closed annular cross section helps to rigidly support the functional head.

[0070] Forming the outer metal shell by means of hydraulic pressure can be used to form a substantially sleeve-shaped or annular outer metal shell with lateral raised portions of increased diameter or increased lateral extension, as well as various other sections of the outer metal shell to form undercuts without the known problems of extracting the punch element or movable core element from the mechanical die system. Forming such undercuts by means of hydraulic pressure applied to the inner surface of the sleeve-shaped outer metal shell is not a problem, because the hydraulic fluid can easily be discharged from the inside of the metal shell.

[0071] More specifically, the outer metal shell may have end portions tapering at both axial ends of the outer metal shell and / or radially or laterally convex intermediate shell sections defining the maximum cross-sectional area of ​​the outer metal shell. In particular, in the case of a non-circular or substantially rectangular or other non-uniform cross-section, the diameter or lateral extension may decrease to the axial end portions and / or may increase in one or more intermediate sections between the end portions. For example, the outer metal shell may form an elongated streamlined rod having a maximum thickness in a middle portion and tapering toward the end portions, or may have a substantially egg-shaped configuration.

[0072] Other shapes with undercuts may also be desirable. For example, it may be desirable to have a raised or elevated platform-like section at one lateral side of the outer metal housing, such as in the middle section, in order to have additional space inside the outer metal housing for accommodating special functional elements, or for example for arranging input switches or touch displays at a lateral elevated position on the outer side of the metal housing. Another option is an organically contoured elongated handle with an ergonomic outer side that fits the fingers and palm of a closed hand.

[0073] Regardless of the shape details of the outer metal shape, a metal shell blank having a hollow, sleeve-like or tubular shape can be positioned in a mold cavity surrounding the outside of the hollow metal shell blank, wherein hydraulic pressure can be applied to the inside of the hollow metal shell blank, thereby expanding the hollow metal shell blank and pressing the outside of the metal shell blank against the contour of the mold cavity, so that the outside of the metal shell blank adopts the contour of the mold cavity.

[0074] The hydroforming step may be a water forming step, wherein the metal shell blank in the die and / or the die is filled with a hydraulic fluid such as water or oil, wherein pressure is applied to the hydraulic fluid from a pressure source external to the die.

[0075] In addition to or as an alternative to such a hydroforming step, an electrohydraulic forming step may be provided, wherein the metal shell blank is positioned in a hydraulic fluid reservoir and / or immersed in a hydraulic fluid, in which one or more pressure waves are generated by means of at least one pair of electrodes, the one or more pressure waves forming the metal shell blank into the desired shape of the outer metal shell. More specifically, such pressure waves may deform the metal shell blank in the die so that the metal shell blank is pressed against the die contour, thereby adopting such a die contour.

[0076] In addition to or as an alternative to such hydroforming or electrohydraulic forming steps, the metal shell blank may also be deformed by electromagnetic forming, in which a metal shell blank made of a magnetically responsive material may be used and the metal shell blank may be subjected to a magnetic field generated by an electromagnetic device. More specifically, a magnetic field may be applied to the metal shell blank to transform the metal sheet blank into a viscoplastic state and deform the metal shell blank to adopt the die contour. Such electromagnetic forming allows complex shapes to be formed at high speeds under cold conditions.

[0077] When such an expanded cross-sectional portion or radially protruding portion is formed by applying hydraulic pressure on the inner side of the metal shell, it may be helpful to apply axial compression to the metal shell blank, wherein such axial compression may be applied before and / or during and / or after the application of hydraulic pressure. More specifically, such axial compression may help push the material of the metal shell blank axially into the die, thereby promoting radial expansion of the metal shell blank, which is primarily achieved by hydraulic pressure. However, when the metal shell blank expands radially, the axial compression helps the material yield and provides a new supply of material to compensate for the radially expanded material.

[0078] In order to achieve such axial compression, an axial force may be applied to one or both axial ends of the metal shell blank, in particular to one or more end portions of the sleeve-shaped or tubular metal shell blank to which hydraulic fluid or hydraulic pressure is supplied in the mold and / or. For example, a pair of push rod elements that may be coaxially arranged with each other may be pushed in opposite directions onto the opposite ends of the metal shell blank received in the mold to apply axial compression. Such axial compression may be applied to the metal shell blank, in particular during the application of hydraulic pressure, at least partially overlapping with the hydraulic forming period.

[0079] The hydroforming step can be configured to produce more than one outer metal shell at the same time or in one hydroforming step. For example, a substantially tubular or sleeve-shaped metal shell blank having a length greater than the sum of the lengths of two or more metal shells can be used, wherein such a sufficiently long metal shell blank can be deformed in the hydroforming step to form, for example, two outer metal shells of the desired shape, which are still connected to each other immediately after the hydroforming stage. The metal shell blank is deformed into an outer metal shell that is connected to each other and arranged in a row one after the other. A plurality of formed shells can be arranged coaxially with respect to each other with their main axes. In a subsequent cutting or separation step, the metal shells formed by hydraulic pressure can be separated from each other, for example by means of cutting the connecting portion between two adjacent metal shells.

[0080] In particular, a pair of outer metal shells can be formed in one hydroforming step so that the metal shells have opposite orientations to each other. For example, when the desired shape of the outer metal shell is a substantially egg-shaped shape, two egg-shaped pieces can be formed in a mold by hydroforming so that the thicker ends of the egg-shaped pieces face each other and the thinner ends of the egg-shaped pieces face away from each other. Such opposite orientations of the pair of metal shells to be formed help achieve uniform deformation of the material and uniform yielding of the material in the section with large radial expansion.

[0081] As mentioned above, the hydraulic forming step may be a water pressure forming step. Alternatively, the hydraulic forming step may include electrohydraulic forming, in which a shock wave or pressure wave is generated in a hydraulic fluid by means of at least one pair of electrodes to which an electric current is applied, thereby generating a kind of explosion in the fluid by the electric current. This pressure wave by the hydraulic pressure hits the surface of the metal shell blank, thereby causing it to deform. In particular, the metal shell blank can be pressed against the wall of the mold receiving the metal shell blank by this pressure wave, basically similar to the above-mentioned water pressure forming process.

[0082] In an alternative to hydroforming and electrohydraulic forming, the metal shell blank can also be deformed into the desired metal shell shape by means of electromagnetic forming (sometimes referred to as EMF). For this EMF forming step, a metal shell blank made of a metal that responds to magnetic forces is used. On the other hand, for hydroforming or electrohydraulic forming, other materials that do not respond to magnetic forces can also be used.

[0083] For example, an aluminum housing may be used, or other materials such as brass, low alloy steel, and stainless steel may be used as the metal housing blank.

[0084] A particularly advantageous material for the outer metal shell is stainless steel, which may include chromium, nickel and molybdenum. More specifically, the steel may include 10 to 25 mass% Cr, 5 to 20 mass% Ni and 1 to 5 mass% Mo, or 16 to 18 mass% Cr, 10 to 14 mass% i and 2 to 3 mass% Mo.

[0085] For example, stainless steel type 1.4301 may be used, or stainless steel type 1.4404 may be used, which provides an even higher corrosion resistance.

[0086] As from Figure 1 and Figure 2 As can be seen in the figure, the handheld personal care device 1 can be an electric shaver 2, which includes an elongated handle 3 and a functional head 4 connected to one end of the handle 3, wherein the functional head 4 can be a razor head. The functional head can form a separate part with a separate housing shell relative to the handle, and a support arm 42 connecting the functional head to the handle is provided, thereby allowing the functional head to be movably (e.g., allowing rotation and / or tilting movement) or immovably supported on the handle. Alternatively, the functional head can be an integral part of the handle, thereby forming the top end of the device, and both can be provided with an integral housing shell.

[0087] The functional head 4 may include one or more functional components to perform or help perform personal care treatment. In the case of a shaver head, the functional components of the functional head 4 may include one or more cutting tools 13, which may include one or more of each of a shear-type foil short hair cutter and / or a long hair cutter and / or a trimmer. The treatment tool may protrude from one side of the body of the functional head 4 to define a skin contact surface.

[0088] As from Fig.11 As can be seen in , the cutting tool 13 is replaceable and is therefore removably supported by the frame of the functional head 4 .

[0089] For activating and / or driving the treatment tool, a drive module may be received in the functional head 4 , wherein such drive module 27 may comprise an electric motor or, as an alternative, a transmitter or a coupling for coupling to a transmitter 12 from another part of the handle 3 .

[0090] The above-mentioned functional components 9 of the functional head 4 can be at least partially accommodated inside the housing 6 in the functional head 4, wherein the housing 6 can include a metal shell 8, which will be described in detail below.

[0091] The elongated handle 3 is used to grasp and hold the personal care device 1, wherein the outer peripheral surface of the handle 3 can be grasped by a hand or fingers of a hand. In addition to this grasping function, the handle 3 is also used to accommodate other functional components 9 of the personal care device 1, wherein the functional components 9 of the handle 3 may include a drive unit 10 for driving a processing tool 13 at the functional head 4. More specifically, the drive unit 10 may include a motor 11, which may be driven by electric energy supplied by a battery 28, or driven via a network cable connected to a power supply terminal.

[0092] The elongated handle 3 comprises a top end portion 17 adjacent to the functional head 4, and a bottom end portion 18 at the opposite side. Each of these end portions can be provided with a front opening 17, 18. As an alternative, the outer shell 7 can be provided with no opening at the bottom end portion 18. At the lateral side of the outer shell 7, at least one lateral opening 21, 22 is provided, which is used to accommodate the front module 32 and / or the rear module 33 therein. Therefore, during assembly, each opening in the outer shell 7 is closed by a cover or module 32, 33, 35, 40, which is preferably made at least partially of plastic.

[0093] In order to control the action of the motor 11, the handle 3 may include a control unit, which may include electronic components, such as an electronic controller. More specifically, the control unit may include a printed circuit board or PCB connected to the motor 11, wherein on the other hand, input / control devices such as control switches, touch screens or other control elements may be connected to the PCB 30, or more generally to the electronic control unit.

[0094] As from Figures 3 to 5 As can be seen in the figure, the elongated handle 3 may include a substantially hollow housing 5 in which the functional components 9 may be received and accommodated. The housing 5 of the handle 3 may include a metal shell 7 that at least partially forms the outer surface of the handle 3.

[0095] The functional components 9 received in the handle 3 can be preassembled to form a preassembled installation unit. For example, the functional components 9 can be preinstalled to a basic structural element 31, which can be at least partially made of, for example, plastic. The above-mentioned basic structural element 31 can also include the above-mentioned printed circuit board 30, to which other components such as motors, batteries or control switches or displays can be installed or connected.

[0096] like Figures 3 to 5 As shown, the functional elements 9 can be grouped differently into preassembled mounting modules. According to an advantageous aspect, the personal care device 1 can be constructed with an elongated internal functional module 29, which can be inserted into the handle 3 via an opening in the axial end of the housing 5. For example, the axial top end portion of the handle 3 facing the functional head 4 can be provided with a front end opening 19, see Figure 6 , the elongated internal functional module 29 can be inserted into the handle 3 through the front end opening. The elongated internal functional module 29 may include, for example, the motor 11, the battery 28, an electronic control unit for controlling the motor 11, and the control unit may include a printed circuit board 30. The internal functional module 29 may have a sealed or sealed construction that protects the electronic components as well as the motor and battery from moisture and water.

[0097] The internal functional module 29 may further comprise a transmitter 12 for transmitting the driving motion of the motor 11 to the processing tool 13 at the functional head 4, wherein a portion of the transmitter 12 may protrude from the axial top end portion of the handle 3 into or towards the functional head 4.

[0098] As from Figures 3 to 5As can be seen in the figure, the front module 32 and / or the rear module 33 can be mounted on the lateral side of the handle 3, wherein the front module 32 and / or the rear module 33 can also be connected to the internal functional components 9 received in the interior of the handle 3. In order to allow the front module 32 and the rear module 33 to be connected to the internal components, the housing 5 of the handle 3, more specifically its outer metal shell 7, can be provided with lateral cutouts or openings 21, 22, and the front module 32, the rear module 33 can at least partially extend into or through these cutouts or openings.

[0099] The front module 32 and the rear module 33 may include electronic and / or electrical components and / or mechanical components and / or tools, wherein the front module 32, the rear module 33 may include parts made of plastic and / or parts made of other materials (such as glass) other than metal, however, some other parts may be formed of metal. For example, the front module 32 may include a display, such as a touch display, for inputting control commands and / or displaying control information, such as, for example, processing time or battery charge status. In addition or as an alternative, the front module 32 may also include a control element, such as a control switch and / or an output element, such as a sound generator or a speaker.

[0100] The rear module 33 may include, for example, a battery module which may be configured to be replaceable. In addition to the battery 28 received in the handle 3, such an additional battery module may be provided, for example, to provide a range extender, or the additional battery module may replace the battery 28 inside the handle 3. In addition or as an alternative, the rear module 33 may include other functional components 9, such as special treatment tools 13. In the case of a shaver 2 or a hair cutter, such special treatment tools 13 may include a long hair cutter.

[0101] As from Figures 3 to 5 As can be seen in the figure, the bottom module 35 can be attached to the handle 3 at the axial end portion opposite to the functional head 4, wherein the handle 3, more specifically its housing 5, and more specifically the metal shell 7 of the handle housing 5 can be provided with a front opening 19, and the bottom module 35 can be at least partially inserted into the front opening. Such a bottom module 35 can be at least partially made of plastic and / or can include electronic components, such as connection terminals for connecting a power cord and / or a charger pin or a charging connector for connecting a charging station. The bottom module 35 can also include data connection terminals to connect the personal care device 1 to a data sending / receiving station.

[0102] The top module 34 can be formed by the above-mentioned functional head 4, wherein such top module 34 can be permanently or removably attached to the top end portion of the handle 3. More specifically, the base portion of the top module 34 that can support the main body of the functional head 4 and / or the functional component 9 can be at least partially inserted into the hollow shell 5 of the handle 3 and / or can be attached to the axial end portion of the handle 3. More specifically, the base portion of the top module 34 can be attached to the metal shell 6 of the handle 3 to connect the functional component 9 of the functional head 4 to the functional component 9 of the handle 3. The top module 34 can be rigidly attached to the metal shell 7 of the handle 3, wherein such rigid attachment can be fixed or releasable, see Figure 3 , Figure 4 and Figure 5 .

[0103] As from Figure 7 As can be seen in the figure, at least one of the above-mentioned functional modules 29, 32 to 35 can be inserted into a corresponding cutout or opening 19, 20 or 21 in the metal shell 7 or the handle 3, so that at least one module 29, 32 to 35 extends partially into the interior of the housing 5 of the handle 3 and partially extends to the outside of the housing, and more specifically, partially inside the metal shell 7 and partially outside the metal shell. More specifically, at least one of the modules 29, 32 to 35 can be constructed to have a protrusion 25 that extends through the corresponding opening 19, 20, 21 in the metal shell 7, and the outer part of the protrusion 25 protrudes beyond the outer surface of the metal shell 7 toward the outside of the handle 3, see Figure 7 Partial view of (b).

[0104] For example, at the interface between the metal shell 7 and the functional module, the protrusion 25 may protrude by an amount of 0.05 mm to 1 mm, or 0.1 mm to 0.5 mm, or 0.1 mm to 0.3 mm beyond the outer surface of the metal shell 7. This protrusion forms a protector that protects the skin and fingers from contacting the edges of the openings 19, 20, and 21.

[0105] However, as an alternative, the functional modules 29, 32 to 35 can be inserted into the corresponding openings 19, 20, 21 in a flush manner, so that the above-mentioned protrusion will be substantially zero, wherein a slight negative protrusion of, for example, -0.1 mm to -0.5 mm is also possible.

[0106] As from Figure 7As can be seen in (b), at least one functional module 29, 32 to 35 can be tightly fitted into the corresponding openings 19, 20 and 21, wherein the peripheral surface of the modules 32 to 35 can match the corresponding openings 19, 20, 21 in terms of shape and size. More specifically, the above-mentioned protrusion 25 extending through the opening can have a peripheral shape that fits the contour of the corresponding openings 19, 20, 21 to achieve a tight fit or allow sealing therebetween.

[0107] As from Figure 7 (b), the protrusion 25 may have a generally cylindrical shape, so that the outer portion of the protrusion 25 may extend substantially perpendicularly or transversely to the outer surface of the metal shell 7. Alternatively, the protrusion 25 may include a collar 26 having a slightly larger diameter or size or extension than the portion of the protrusion that sits in the openings 19, 20, 21. Such a collar 26 may be seated on the outer surface of the metal shell 7.

[0108] The above-mentioned protrusions 25 of the corresponding functional modules 29, 32 to 35 seated in the corresponding openings 19, 20 and 21 can be at least partially formed of plastic, wherein such plastic can be hard plastic or soft plastic or a mixture thereof, so as to snap-fit ​​the corresponding modules into the corresponding openings while sealing the interface between the metal shell 7 and the attached module.

[0109] As from Figures 11 to 13 As can be seen in FIG. 1 , the functional head 4 can have a similar construction to the functional head housing 6 and the functional module or functional component 9 attached thereto. More specifically, the functional component or component group 9 can be at least partially inserted into the interior of the housing 6 of the functional head 4. More specifically, the functional component 9 can include a protrusion 25 that protrudes beyond the outer surface of the metal shell 8 of the head housing 6 to the outside thereof, wherein see Fig.13 , the protrusion may be in the range of 0.05 mm to 1 mm or 0.1 mm to 0.5 mm or 0.1 mm to 0.3 mm. Likewise, as described for the functional module of the handle 3, it is basically possible to have no height difference to achieve a flush configuration or a negative height difference.

[0110] The protrusion 25 attached to the base structural element of the functional head 4 may also be at least partially formed from plastic, wherein such plastic may be hard plastic and / or soft plastic to achieve a snap fit and / or a seal.

[0111] The metal shell 7 of the handle 3 and / or the metal shell 8 of the functional head 4 may be hydroformed. More specifically, the manufacture of the metal shells 7, 8 may include a hydroforming step, which includes applying a high-pressure hydraulic fluid to the inner surface of the metal shell blank 14, such as Figure 8 and Fig. 9 As illustrated in more detail in .

[0112] Reference Figure 8 , a metal shell blank 14, which may initially have a tubular shape, is inserted into an open mold 15, which, when closed, may define a cavity corresponding to the desired shape of the outside of the metal shell 7, 8. Figure 8 As can be seen in Fig. 1 , the metal shell blank 14 can be inserted so that the opposite end portions of the tubular blank 14 reach the opposite edge portions of the die 15 at the interface of the two die portions. The end portions of the tubular metal shell blank 14 should be accessible from the outside of the die 15 to allow the hydraulic fluid to be supplied to the interior of the tubular metal shell blank 14. In addition, the push rod element 37 should be able to contact the opposite end portions of the tubular metal shell blank 14 to apply axial compression thereto.

[0113] See also Figure 8 b. When the mold 15 is closed and the fluid supply connector is connected to the end portion of the tubular metal shell blank 14 and / or the push rod element 37 is positioned at the end portion of the tubular metal shell blank 14, the hydraulic fluid is injected into the interior of the tubular metal shell blank 14 via its open axial end, see Figure 8 c, to completely fill the interior of the metal shell blank 14, see Figure 8 c.

[0114] The hydraulic pressure is then increased to achieve deformation of the metal shell blank 14, and more specifically, to achieve radial expansion thereof, thereby pressing the metal shell blank 14 against the mold surface defining the cavity of the mold 15 so that the metal shell blank 14 can adopt the shape of the mold cavity, see Figure 8 d.

[0115] Before and / or during and / or after the radial expansion of the metal shell blank 14 due to hydraulic pressure, the push rod 37 can be activated to apply axial compression to the metal shell blank 14. More specifically, the push rod element 37 can be pressed against the opposite end portions of the tubular metal shell blank 14, see Figure 8 d, to support the desired deformation of the material of the metal shell blank 14.

[0116] When the metal housing blank 14 is located in the die 15, axial compression may be applied.

[0117] Fig. 9 a and Fig. 9 b illustrates the transition and deformation of the metal shell blank 14 into the outer metal shells 7, 8 having the desired shape. According to an advantageous aspect, a pair of metal shells 7, 8 can be formed in one water pressure forming or hydraulic forming step, see Fig. 9 b, wherein the mold 15 can be configured to achieve water pressure forming or hydraulic forming of a pair of outer metal shells 7, 8 oriented relative to each other. Fig. 9 As can be seen in FIG. 2 , the two metal shells 7 , 8 can face each other with their thicker end sections and can face away from each other with their thinner end sections, wherein the two metal shells can be arranged with their main axes essentially coaxially with each other.

[0118] After the hydroforming step, the metal shell or the pair of metal shells can be removed from the die to carry out one or more cutting steps. In particular, the axial end portions of the formed metal shells 7, 8 can be cut off, see Fig. 9 c. This cutting step may include different cutting techniques, such as laser cutting, sawing and / or milling.

[0119] As from Fig. 9 As can be clearly seen in FIG. 2c, the above-mentioned front openings 19, 20 at the axial end portions of the metal shells 7, 8 are made by means of such cut end portions.

[0120] like Fig. 9 d, one or more lateral openings 21 may also be cut in the metal housing 7, 8 to allow for the installation of the above-mentioned front module 32 and rear module 33. Incidentally, it should be noted that other lateral openings may also be cut in the lateral sides of the outer metal housing 7, 8. For example, perforations may be cut or drilled to allow visual contact with components inside the metal housing, such as displays or LEDs, etc.

[0121] like Fig.10 As illustrated, the openings 19, 20, 21 or cuts can be performed in different ways and with different cutting techniques. Fig.10 As shown in Fig. 1, the opening can have a sharp edge and / or an edge profile which has a substantially cylindrical configuration with respect to the parallel extension of all sections of the cut edge. Such a configuration can be achieved, for example, by drilling a hole or moving another cutting tool (such as a saw or a milling tool) in a fixed orientation relative to the metal shell 7, 8. For example, the metal shell 7, 8 can be fixedly held in a horizontal orientation, while the milling tool is fixedly held in a vertical orientation and moved in a horizontal plane to achieve the desired cut profile machining.

[0122] As an alternative, Fig.10 As illustrated in FIG. 1 , an opening or cutout can be produced by means of 3D cutting, wherein the orientation of the cutting tool is adjusted or varied along the displacement path of the cutting tool, so that the edge of the obtained opening has different orientations in different sectors of the opening.

[0123] More specifically, such 3D cutting can be configured to adjust the orientation of the cutting tool to the inclination and / or orientation and / or slope of the outer surface of the metal shell segment being cut. More specifically, the orientation of the 3D cutting tool can be adjusted so that the edge of the obtained opening is substantially perpendicular to the outer surface of the metal shell adjacent to or surrounding the opening, see Fig.10 b, wherein the outer surface adjacent the opening may change its orientation along the opening and / or may have a curved shape, such as a barrel shape, or may have a multi-axial curved profile.

[0124] For example, such 3D cutting may include laser cutting using a laser cutter that can pivot about two or three axes, wherein translational displacement of the laser relative to the metal shell can be achieved by translation of a fixture that holds the metal shell during the cutting process, and / or translation of the laser cutter. The fixture that holds the metal shell may also be pivoted to achieve 3D cutting, and the orientation of the laser may be adjusted relative to the slope or orientation of the metal shell surface.

[0125] This 3D cutting can also use other cutting techniques, such as milling or water jet cutting.

[0126] As from Fig.14 As can be seen in the figure, the hydraulic forming step for forming the metal shells 7, 8 can also include electrohydraulic forming, sometimes referred to as EHF. This electrohydraulic forming is based on the use of shock waves or pressure waves in a hydraulic fluid such as water to deform the metal shell blank at ultra-high speed. An electric arc can be generated in the water between at least one pair of electrodes via a discharge current. This electric arc evaporates the surrounding water and / or hydraulic fluid, thereby converting electrical energy into a high-pressure wave of mechanical energy. This shock wave can simultaneously transform the metal shell blank 14 into a viscoplastic state and press and / or accelerate the metal shell blank 14 onto the surface of the mold cavity, thereby forming the desired shape at high speed under cold conditions. This electrohydraulic forming is particularly capable of forming complex shapes.

[0127] like Fig.15 As illustrated, the forming step for forming the outer metal shell 7, 8 into the desired shape can also use electromagnetic forming called EMF. This electromagnetic forming is based on ultra-high-speed deformation of metal using a magnetic field. For example, via a discharge current in a coil, a magnetic field can be generated, which can simultaneously transform the metal shell blank into a viscoplastic state and press / accelerate the metal shell blank onto the surface of the mold cavity, thereby forming the metal shell into the desired shape at high speed under cold conditions. In addition, this electromagnetic forming can form complex shapes.

[0128] 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 personal care device such as a hair cutter or a toothbrush, the personal care device comprising a handle (3) and a functional head (4) supporting at least one personal care tool, the functional head (4) being attached to the handle (3), wherein at least one of the handle (3) and the functional head (4) comprises an outer metal shell (7, 8), the metal shell (7, 8) having at least one opening (19, 20, 21), wherein at least one plastic base structural member (31, 32, 33, 35, 40) is accommodated in the outer metal shell (7, 8), characterized in that The plastic base structural component (31, 32, 33, 35, 40) has a protrusion (25) which passes through the opening (19, 20, 21, 22) in the outer metal shell (7, 8) and protrudes beyond the outer surface of the metal shell section surrounding the opening (19, 20, 21, 22), and / or the plastic base structural component completely covers the outer edge of the opening (19, 20, 21, 22).

2. A personal care device according to claim 1, wherein the outer metal shell (7, 8) includes at least one lateral opening (21, 22), and a functional component (9) that at least partially extends to the outside of the outer metal shell (7, 8) and / or can be accessed from the outside of the outer metal shell is connected to another functional component (9) accommodated inside the outer metal shell (7, 8) through the at least one lateral opening.

3. A personal care device according to any one of the preceding claims, wherein the handle is provided with a front module and a rear module at opposite lateral sides thereof, each module being provided with the plastic base structural member extending through a corresponding opening of the outer metal shell (7).

4. A personal care device according to any one of the preceding claims, wherein the handle is provided with a top module and a bottom module at opposite longitudinal sides thereof, each module being provided with the plastic base structural member extending through a corresponding opening of the outer metal shell (7).

5. The personal care device according to any one of the preceding claims, wherein the functional head (4) is provided with the plastic base structural member (31), which extends through the bottom opening and the top opening of the functional head (4).

6. A personal care device according to any one of the preceding claims, wherein the protrusion (25) comprises a collar (26) overlapping the opening (19, 20, 21, 22) and / or seated on the outer surface of the metal shell section surrounding the opening (19, 20, 21, 22).

7. A personal care device according to any of the preceding claims, wherein the protrusion (25) protrudes beyond the outer surface of the metal shell (7, 8) by a certain amount, the amount being substantially constant along the entire opening (19, 20, 21, 22) even when the contour of the opening does not extend in a plane; and / or protrudes beyond an amount in the range of 0.05 mm to 1 mm or 0.1 mm to 0.5 mm or 0.1 mm to 0.3 mm.

8. A personal care device according to any one of the preceding claims, wherein the protrusion (25) is made of soft plastic and / or hard plastic, and the outer contour of the protrusion matches the inner contour of the opening (19, 20, 21, 22) in terms of shape and size to provide a sealing and / or shape-fitting and / or snap-fitting connection between the protrusion and the metal shell (7, 8).

9. A personal care device according to any one of the preceding claims, wherein the metal shell (7, 8) has opposite end portions (17, 18), each end portion defining a closed annular cross-section, wherein the intermediate section (16) between the opposite end portions (17, 18) includes at least one lateral opening and / or lateral perforation for accessing at least one functional component (19) housed inside the outer metal shell (7, 8).

10. The personal care device according to any of the preceding claims, wherein the outer metal shell (7, 8) forms a unitary piece having a unitary, homogeneous, seamless structure having a ring-like or sleeve-like shape with a closed annular cross-section.

11. Personal care device according to the preceding claim, wherein the outer metal shell (7, 8) is a hydroformed part and / or a water pressure formed part by hydraulic deformation.

12. A personal care device according to any one of the preceding claims, characterised in that The outer metal shell (7, 8) comprises at least one undercut portion (23).

13. A personal care device according to any one of the preceding claims, wherein the outer metal shell (7, 8) includes at least one opening (19, 20, 21) surrounded by a three-dimensional shaped metal shell segment, the opening (19, 20, 21) having a three-dimensional shaped edge profile (22), the three-dimensional shaped edge profile extending along the entire profile of the opening substantially perpendicular to the surrounding metal shell segment, and the surrounding shell portion adjacent to and surrounding the opening (19, 20, 21) having a variable orientation along the opening (19, 20, 21).

14. A personal care device according to any of the preceding claims, wherein the metal shell (7, 8) has opposite end portions (17, 18), each end portion defining a closed annular cross-section, wherein the intermediate section (16) between the opposite end portions (17, 18) includes at least one lateral opening and / or lateral perforation for accessing at least one functional component (19) housed inside the outer metal shell (7, 8).

15. A personal care device according to any one of the preceding claims, wherein the outer metal shell (7, 8) has an elongated hollow shape having a front opening (19, 20) at opposite axial end portions, the axial end portions having a closed annular cross-section surrounding the opening (19, 20).

16. A personal care device according to any of the preceding claims, wherein the metal shell (7, 8) is made of stainless steel or a steel containing chromium, nickel and molybdenum, in particular 10% to 25% by mass of Cr, 5% to 20% by mass of Ni and 1% to 5% by mass of Mo or 16% to 18% by mass of Cr, 10% to 14% by mass of Ni and 2% to 3% by mass of Mo.

17. A method of manufacturing a handheld personal care device such as a hair cutter or toothbrush having an outer metal housing, the method comprising the steps of: forming the outer metal shell (7, 8) into a desired shape, and installing a functional component (9) for performing or assisting in performing a personal care function in and / or on the shaped outer metal shell (7, 8), It is characterized in that The forming step includes a hydraulic forming step of applying hydraulic pressure to one side of a metal shell blank (14) positioned in a die (15) to deform the metal shell blank (14) and press an opposite side of the metal shell blank (14) against the die (15) to adopt a contour of the die (15), thereby forming the outer metal shell having the desired shape, providing a cutting step for forming at least one opening in the outer metal shell, and A plastic base structure part is mounted in the at least one opening and wherein an outer edge of the opening is covered by the plastic base structure part and / or the plastic base structure part protrudes beyond the outer metal shell.

18. A method according to the preceding claim, wherein the metal shell blank (14) has a hollow, sleeve-like or tubular shape and is positioned in the cavity of the mold (15) surrounding the outside of the metal shell blank (14), wherein the hydraulic pressure is applied to the inside of the hollow metal shell blank, thereby expanding the hollow metal shell blank and pressing the outside of the metal shell blank (14) against the contour of the cavity of the mold (15), so that the outside of the metal shell blank (14) adopts the contour of the mold (15).

19. Method according to any of the preceding claims, wherein one or more undercut portions (23) of the outer metal shell (7, 8) are hydroformed during the hydroforming step.

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