Method for manufacturing a hair cutter

Abstract

The present invention relates to a method of manufacturing a hair cutting device having an external metal shell, the method including: forming the external metal shell into a desired shape; and attaching functional components for performing or assisting in performing personal care treatments within and / or on the formed external metal shell. Forming the external metal shell includes a hydroforming process.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a personal care device such as a hair cutter having an external metal shell, the method including the steps of forming the external metal shell into a desired shape and attaching functional components for performing or assisting in performing personal care treatments inside and / or on the formed external metal shell. The personal care device may include a handle and a functional head such as a cutter head or a brush head attached to the handle, and at least one of the handle and the functional head includes the above-mentioned external metal shell, which may be part of a housing containing an electric drive unit including an electronic device, a motor, and a mechanical transmission device, or a power source such as a battery or a functional component such as a power storage component. The personal care device may also include a base station for loading and / or cleaning and / or parking the handheld device, and the base station may also include an external metal shell as described above, which may be part of a housing containing functional components such as an electronic device, a power source, or a cleaning tool.

Background Art

[0002] A handheld personal care device can perform various personal care functions such as hair cutting, shaving, skin treatment, teeth brushing and cleaning, nail trimming, or other personal care procedures. Usually, the handle of such a personal care device has a dual function. On the one hand, the handle is a gripping part for gripping and holding the personal care device by hand. On the other hand, the handle houses or supports functional components such as an electric drive unit for driving personal care tools such as a hair cutting tool, a brush unit, a skin peeling or massage tool, a nail grinding tool, or other personal care tools. More specifically, the handle can form a housing that can accommodate an electric motor, a mechanical transmission device for transmitting the driving motion of the motor to the personal care tool, further, electronic control devices, a power supply device such as a battery, a net supply terminal, and an information device such as a display. The handle may be waterproof and / or sealed against moisture and / or dust to protect the functional components housed within the housing.

[0003] The functional head of such a personal care device usually supports one or more personal care tools such as a shear-type foil cutter, a long hair cutter, a trimmer, or one or more brush units, an interdental cleaner, etc. Such personal care tools may be movably supported with respect to the frame or shell of the functional head, and a mechanical transmission device may connect the movably supported tool to the drive unit within the handle.

[0004] The base station may receive or be connected to the handheld personal care device to load and / or clean and / or park the handheld device. The housing of the base station usually houses functional components such as an electronic device such as a data processor and a display for communicating with the handheld device, a power supply having an electrical connector for charging the handheld device, or a cleaning tool such as a cleaning machine for cleaning the functional head of the handheld device.

[0005] Generally, the outer shell of the handle, the outer shell of the functional head, and the outer shell of the base station are mainly made of plastic, and a plurality of plastic parts such as rigid plastic parts and soft plastic parts may be attached to each other to form the outer shell.

[0006] On the other hand, the handle and / or the functional head may include an external metal shell, and the external metal shell may form the outer surface of the handle that is gripped by the hand or finger, and / or at least part of the housing that houses the aforementioned functional components, and / or may form a frame for supporting the personal care tool of the functional head. When such a metal shell forms the outer surface of the handle and / or the functional head, it can provide a cold feeling to the user, has high strength and rigidity, and further has high resistance to wear, tearing, scratching, and chemical environment. In addition, the external metal shell provides a precious aesthetic appearance and a clean appearance.

[0007] When attaching functional components inside and / or on such an external metal shell, it is very difficult to enable both the easy and accurate manufacturing of the metal shell on the one hand and the easy assembly of the personal care device including the attachment of functional components on the other hand when the external metal shell has a precise fit and small dimensions. Furthermore, the openings and perforations in the metal shell used for inserting functional components or providing access to functional components such as displays, controllers, or switches, or connectors such as loading cable terminals may have sharp and burr-edged.

[0008] If the outer shell is to have a hollow shape and be made of a single, integral, homogeneous and seamless structure, it becomes even more difficult to meet such different requirements. Such an integral structure without visible seams, such as a welded joint between different shell parts, is not only desirable from an aesthetic point of view, but also increases strength and rigidity and reduces the mounting process. However, such an integral structure having a hollow ring-shaped or sleeve-shaped configuration requires at least one opening through which the aforementioned functional components such as electronic devices, drive units or batteries or mechanical transmission devices can be inserted or through which access to the internal components can be obtained. Providing a large opening facilitates the mounting process but reduces strength, while a small opening does not allow for easy mounting. In any case, it is difficult to achieve a perfect fit between the metal shell and the functional components without compromising the ergonomic shape and aesthetically pleasing three-dimensional complex appearance.

Summary of the Invention

Means for Solving the Problems

[0009] The underlying object of the present invention is to provide an improved method for manufacturing a hair cutting device comprising an external metal shell and / or a metal housing.

[0010] A further underlying object of the present invention is to provide an improved manufacturing method for such a personal care device having an external metal shell that combines a small installation area, a perfect fit with functional components mounted within and / or on the metal shell, and easy mounting of the functional components, without sacrificing the functional shape of the external metal shell that provides rigidity and ergonomic handling.

[0011] A further object underlying the present invention is to provide an improved manufacturing method for manufacturing an external metal shell of a personal care device that enables the accurate formation of a metal shell despite its complex three-dimensional shape without the need for a large number of processing steps using complex and expensive tools.

[0012] At least one of the aforementioned objects is solved by a method having the features of claim 1. Advantageous further features are described by the dependent claims.

[0013] At least one of the aforementioned objects is achieved by a method for manufacturing a hair cutter having an external metal shell, the method including the step of forming the external metal shell into one integral part having a desired shape, a homogeneous seamless structure, and a hollow elongated closed ring or closed sleeve shape, the forming step including disposing a hollow sleeve-shaped or pipe-shaped metal shell blank within a cavity of a mold surrounding the outside of the metal shell blank, applying hydraulic pressure inside the hollow metal shell blank, thereby expanding the hollow metal shell blank, and pressing the metal shell blank against the contour of the mold cavity on the outside so that the outside of the metal shell blank takes the shape of the contour of the mold; in the formed external metal shell, creating front openings at opposite axial ends, preferably creating at least one lateral opening or perforation at an intermediate side portion; and mounting functional components and / or modules that perform or assist in performing personal care functions within and / or on the formed external metal shell.

[0014] In order to achieve at least one of the foregoing objects, it is proposed to form the outer metal shell at least partially by means of a hydraulic pressure that deforms the metal shell into a desired shape. More specifically, the step of forming the outer metal shell includes applying a hydraulic pressure to one side of a metal shell blank disposed in a mold to deform the metal shell blank, pressing the opposite side of the metal shell blank against the mold to take the shape of the contour of the mold, thereby including a hydraulic forming step of forming an outer metal shell having a desired shape. Such a hydraulic forming step enables the metal shell blank to be deformed into a complex three-dimensional shape without having the problem that mechanical forming tools such as punches, pushers, or movable core elements come out of the recesses of the metal shell.

[0015] An opening is made in the metal shell formed in this way, and this metal shell can be equipped with functional components or modules attached therein and / or thereon. Thereby, it becomes possible to produce a series of devices provided with different functional components or modules that are inserted into these openings and based on the same metal shell housing. An intermediate portion between both ends is formed in the outer metal shell, including at least two lateral openings and / or lateral perforations for accessing or connecting to the functional components housed inside or outside the outer metal shell.

[0016] The functional component or module includes at least three, four, five, or all of the following: a drive unit, a charging connector provided at the lower end, a charging connector provided at the lateral opening, a display provided at the lateral opening, a hair cutting tool provided at the upper end, and / or a special treatment tool provided at the lateral side or the lower end of the outer metal shell.

[0017] More specifically, the outer metal shell can include one or more undercuts, and these one or more undercuts can be easily formed by applying hydraulic pressure to a shell portion that desirably has such an undercut shape. Forming such an undercut by hydraulic pressure is possible even when the outer metal shell is formed of a single homogeneous and integral seamless structure having a closed ring shape or a closed sleeve shape. For example, a substantially tubular and elongated outer metal shell of a handle, or a hollow sleeve-shaped 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 be formed by applying hydraulic pressure to the inner surface of a substantially tubular metal shell blank to form an outer metal shell having an intermediate portion that defines a maximum cross-sectional area and a pair of end portions disposed on both sides of the intermediate shell portion and having a cross-sectional area smaller than that of the bulged intermediate portion.

[0018] Regardless of the details of the shape of the outer metal shell, a metal shell blank having a hollow, sleeve-shaped, or pipe-shaped configuration may be disposed within a cavity of a mold that surrounds the outside of the hollow metal shell blank, where 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 against the contour of the mold cavity, and causing the outside of the metal shell blank to take the shape of the contour of the mold cavity.

[0019] The aforementioned hydraulic forming process may be a hydroforming process in which the metal shell blank and / or the mold within the mold is filled with a working fluid such as water or oil, and pressure is applied to the working fluid from a pressure source outside the mold.

[0020] In addition to, or instead of, such a hydroforming process, a metal shell blank may be disposed within a working fluid reservoir and / or immersed in a working fluid, and one or more pressure waves may be generated, for example, by at least one pair of electrodes, and the one or more pressure waves may form the metal shell blank into the desired shape of an external metal shell, and an electrohydraulic forming process may be provided. More specifically, such pressure waves may deform the metal shell blank within a mold, press the metal shell blank against the mold contour, and cause the metal shell blank to take the shape of such a mold contour.

[0021] In addition to, or instead of, such a hydroforming or electrohydraulic forming process, the metal shell blank may also be deformed by electromagnetic forming, and a metal shell blank made of a magnetically responsive material may be used, and such a metal shell blank may be subjected to a magnetic field that can be generated by an electromagnetic device. More specifically, a magnetic field may be applied to the metal shell blank to convert the metal sheet blank into a viscoplastic state and deform the metal shell blank to take the shape of a mold contour. Such electromagnetic forming enables the formation of complex shapes at high speed under low-temperature conditions.

[0022] These and other advantages will become apparent from the following description with reference to the drawings and possible examples.

Brief Description of the Drawings

[0023]

Figure 1

Figure 2

Figure 3

Figure 4

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Figure 6

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Figure 9

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Figure 15

DETAILED DESCRIPTION OF THE INVENTION

[0024] According to one aspect, it is proposed to at least partially form the outer metal shell by hydraulic pressure that deforms the metal shell into a desired shape. More specifically, forming the outer metal shell involves applying hydraulic pressure to one side of a metal shell blank placed in a mold to deform the metal shell blank, pressing the opposite side of the metal shell blank against the mold to take the shape of the mold's contour, thereby including a hydraulic forming process for forming an outer metal shell having a desired shape. Such a hydraulic forming process enables the metal shell blank to be deformed into a complex three-dimensional shape without the problem of mechanical forming tools such as punches, pushers, or movable core elements disengaging from the indentation of the metal shell.

[0025] More specifically, the outer metal shell can include one or more undercuts, but these one or more undercuts can be easily formed by applying hydraulic pressure to the shell portion that desirably has such an undercut shape. Forming such an undercut by hydraulic pressure is easily possible even when the outer metal shell is formed of a single part having a homogeneous and integral seamless structure with a closed ring shape or a closed sleeve shape.

[0026] For example, a substantially tubular and elongated outer metal shell of a handle, or a hollow sleeve-shaped 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, may be formed by applying hydraulic pressure to the inner surface of a substantially tubular metal shell blank to form an outer metal shell having an intermediate portion that defines a maximum cross-sectional area and a pair of end portions disposed on both sides of the intermediate shell portion and having a cross-sectional area smaller than the bulged intermediate portion.

[0027] Another example of such an undercut shape may include a substantially hemispherical concave or bowl-shaped spherical portion that is closed with respect to the outside of the shell and open with respect to the inside thereof. Also, for example, an outer platelike ridge that forms a finger gripping portion or a support portion for an additional element may also be formed in an open state inside the metal shell by an undercut method.

[0028] Regardless of the details of the shape of the outer metal shell, a metal shell blank having a hollow, sleeve-shaped, or pipe-shaped configuration may be disposed within a cavity of a mold that surrounds the outside of the hollow metal shell blank, and hydraulic pressure may be applied inside 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 and causing the outside of the metal shell blank to take the shape of the mold cavity contour.

[0029] The aforementioned hydraulic forming process may be a hydroforming process in which the metal shell blank and / or the mold within the mold is filled with a working fluid such as water or oil, and pressure is applied to the working fluid from a pressure source outside the mold.

[0030] In addition to, or instead of, such a hydroforming process, a metal shell blank may be disposed within a working fluid reservoir and / or immersed in a working fluid, and one or more pressure waves may be generated by at least one pair of electrodes, and the one or more pressure waves may form the metal shell blank into the desired shape of an external metal shell, and an electrohydraulic forming process may be provided. More specifically, such pressure waves may deform the metal shell blank within a mold, press the metal shell blank against a mold contour, and cause the metal shell blank to take the shape of such a mold contour.

[0031] In addition to, or instead of, such hydroforming or electrohydraulic forming processes, the metal shell blank may also be deformed by electromagnetic forming, where a metal shell blank made of a magneto-responsive material may be used, and such a metal shell blank may be subjected to a magnetic field that can be generated by an electromagnetic device. More specifically, a magnetic field may be applied to the metal shell blank to convert the metal sheet blank into a viscoplastic state and deform the metal shell blank to take the shape of a mold contour. Such electromagnetic forming enables the formation of complex shapes at high speed under low-temperature conditions.

[0032] The outer metal shell may be formed to have a single-piece structure. More specifically, the metal shell may be formed of one integral piece having a homogeneous seamless structure, and the outer metal shell may have a closed ring shape or a closed sleeve shape so as to provide high strength and rigidity by a closed cross-section. However, the ring-shaped or sleeve-shaped outer metal shell may have one or more lateral openings or lateral notches, and of course, no closed annular cross-section exists in the region of such notches. However, the outer metal shell may be formed to have an annular cross-section having a closed ring shape at least at both ends of the outer metal shell and / or on both sides of the lateral opening. These axial ends of the outer metal shell, considering the outer metal shell of the handle of the personal care device, can, on the one hand, face and support the functional head of the personal care device, and on the other hand, can form the bottom end of the handle. Considering the functional head, the opposing ends of the outer metal shell may, on the one hand, face the handle, and on the other hand, may support the personal care treatment tool and / or may surround or be adjacent to the skin contact surface of the functional head.

[0033] Such a closed annular cross-section at the end can provide strong and firm support for the rigidity of the housing or frame, especially for the functional elements mounted in and on the outer metal shell. Nevertheless, openings may be provided on the axial end side itself of the metal shell, and these openings may be surrounded by the annular portion having a closed annular cross-section. For example, a support structure for supporting the functional head is usually attached to or supported on one of the axial ends of the handle, and thus, providing a closed annular cross-section at such an end of the outer metal shell helps to firmly support the functional head.

[0034] By utilizing the formation of an external metal shell by hydraulic pressure, a substantially sleeve-shaped or ring-shaped external metal shell can be formed to have a laterally bulged portion with an increased diameter or an increased lateral spread, and various other portions of the external metal shell that form undercuts, without having the problem that known punching elements or movable core elements will come off from the mechanical die system. Forming such undercuts by the hydraulic pressure applied to the inner surface of the sleeve-shaped external metal shell is not a problem because the working fluid can be easily discharged from the inside of the metal shell.

[0035] More specifically, the hydraulic forming can taper the ends at both axial ends of the external metal shell and / or enable the realization of an intermediate shell section that bulges in the radial or lateral direction defining the maximum cross-sectional area of the external metal shell. In particular, the lateral spread in the case of a diameter, or a non-circular or substantially rectangular or other non-uniform cross-section, may decrease towards the axial ends and / or may increase in one or more intermediate portions between the ends. For example, the external metal shell may form an elongated, streamlined bar having a maximum thickness at the central portion and tapering towards the ends, or may have a substantially oval configuration.

[0036] Other shapes with undercuts may also be desirable. For example, it may be desirable to have an inflated or raised terrace-like portion, for example, at the central portion, on one lateral side of the external metal shell so as to have additional space inside the external metal shell to accommodate special functional elements, or to place, for example, an input switch or a touch display at a laterally raised position outside the metal shell. Another option is an elongated handle with an organic contour having an outer side ergonomically adapted to a closed hand's fingers and palm.

[0037] When forming such an expanded cross-sectional portion or radially raised portion by applying hydraulic pressure inside the metal shell, it may be helpful to apply an axial compressive force to the metal shell blank, and such an axial compressive force can be applied before, during, and / or after applying the hydraulic pressure. More specifically, such an axial compressive force helps to push the material of the metal shell blank axially into the mold, thereby facilitating the radial expansion of the metal shell blank, which can be achieved mainly by hydraulic pressure. Nevertheless, when the metal shell blank expands radially, the axial compression helps the material to yield and provides a certain fresh supply of material to compensate for the material expanding radially.

[0038] To achieve such axial compression, an axial force may be applied to one or both axial ends of the metal shell blank, particularly to one or more ends where the hydraulic fluid or hydraulic pressure is supplied into the mold and / or into the sleeve-shaped or tubular metal shell blank. For example, a pair of pusher elements that can be coaxially arranged with each other can push both ends of the metal shell blank received in the mold in opposite directions so as to apply an axial compressive force. Such an axial compressive force may be applied to the metal shell blank, particularly during the application of hydraulic pressure, which at least partially overlaps with the period of hydroforming.

[0039] The hydraulic forming process may be configured to produce two or more external metal shells simultaneously or in one hydraulic forming process. 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 may be used. Such a sufficiently long metal shell blank may be deformed in the hydraulic forming process to form two external metal shells having a desired shape that are, for example, still connected to each other immediately after the hydraulic forming process. The metal shell blank is deformed into a certain row of external metal shells that are connected to each other and arranged in a row one after another. The plurality of formed shells can be arranged with their main axes coaxial with each other. The metal shells formed by hydraulic pressure may be separated from each other in a subsequent cutting or separating process, for example, by cutting the connection portion between two adjacent metal shells.

[0040] In particular, a pair of external metal shells may be formed in one hydraulic forming process such that the metal shells have opposite orientations to each other. For example, when the desired shape of the external metal shell is a substantially oval shape, the two eggs may be formed in the mold by hydraulic forming such that the thicker ends of the eggs face each other and the thinner ends of the eggs face away from each other. The formation of the pair of metal shells in such opposite orientations helps to achieve uniform deformation of the material and uniform yielding of the material in sections having a large radial expansion.

[0041] As described above, the hydraulic forming process may be a hydroforming process. Alternatively, the hydraulic forming process may include electrohydraulic forming, in which a shock wave or pressure wave is generated in the working fluid by at least a pair of electrodes to which an electric current is applied, and thus a kind of explosion in the working fluid is generated by the electric current. The pressure of such a hydraulic pressure wave hits the surface of the metal shell blank, thereby causing its deformation. In particular, the metal shell blank can be pressed against the wall of the mold in which the metal shell blank is received by such a pressure wave, substantially in the same manner as in the aforementioned hydroforming process.

[0042] Instead of hydroforming and electrohydraulic forming, the metal shell blank may be deformed into the desired shape of the metal shell by electromagnetic forming, which is sometimes known as EMF. For such an EMF forming process, a metal shell blank made of a metal that responds to magnetic force is used. On the other hand, for hydroforming or electrohydraulic forming, other materials that do not respond to magnetic force can also be used.

[0043] For example, an aluminum shell may be used, or other materials such as brass, low alloy steel, and stainless steel may be used as the metal shell blank.

[0044] A particularly advantageous material for the outer metal shell is stainless steel, which can contain chromium, nickel, and molybdenum. More specifically, the steel may contain 10-25% by mass of Cr, 5-20% by mass of Ni, and 1-5% by mass of Mo, or may contain 16-18% by mass of Cr, 10-14% by mass of Ni, and 2-3% by mass of Mo.

[0045] Preferably, one metal shell blank can be used to produce two or more outer shells. In that case, the forming process includes cutting the formed part into two or more outer shell pieces. Therefore, cost-effective mass production is possible.

[0046] For example, stainless steel of type 1.4301 may be used, or stainless steel 1.4404 may be used, which provides further increased corrosion resistance.

[0047] As can be seen from FIGS. 1 and 2, the handheld personal care device 1 may be an electric shaver 2 including an elongated handle 3 and a functional head 4 attached to one end of the handle 3, and the functional head 4 may be a shaver head. The functional head may form a separate part having a separate housing shell with respect to the handle, and a support arm 42 is provided to connect the functional head and the handle so as to support the functional head movably (for example, enabling swiveling and / or tilting movements) or non - movably with respect to the handle. Alternatively, the functional head may be an integral part of the handle forming the upper end of the device, and an integral outer shell may be provided for both of them.

[0048] The functional head 4 may include one or more functional components for performing or assisting in performing personal care procedures. 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 a shear - type foil short - hair cutter and / or a long - hair cutter, and / or a trimmer. The treatment tool may project from one side of the body of the functional head 4 to define a skin - contacting surface.

[0049] As can be seen from FIG. 11, the cutting tool 13 may be replaceable and thus may be removably supported by the frame of the functional head 4.

[0050] To operate and / or drive the treatment tool, a drive module may be received within the functional head 4, and such a drive module 27 may include an electric motor or, alternatively, a transmission or coupling for coupling to another part of the transmission device 12 coming from the handle 3.

[0051] The aforementioned functional components 9 of the functional head 4 may be at least partially received within the housing 6 of the functional head 4, and the housing 6 may include a metal shell 8 which will be described in detail below.

[0052] The elongated handle 3 serves the purpose of gripping and holding the personal care device 1, and the outer peripheral surface of the handle 3 can be gripped by a hand or a finger of a hand. In addition to such a gripping function, the handle 3 also serves the purpose of accommodating further functional components 9 of the personal care device 1, and the functional components 9 of the handle 3 may include a drive unit 10 for driving the treatment tool 13 at the functional head 4. More specifically, the drive unit 10 may include a motor 11 that can be driven by the battery 28 or by electrical energy supplied via a network cable connected to a power supply terminal.

[0053] The elongated handle 3 includes an upper end portion 17 adjacent to the functional head 4 and a lower end portion 18 on the opposite side. Front openings 17, 18 may be provided at each of these end portions. In an alternative example, the outer shell 7 may not be provided with an opening at the bottom end portion 18. At least one lateral opening 21, 22 is provided on the lateral side surface of the outer shell 7 to accommodate the front module 32 and / or the back module 33 therein. Thus, during assembly, each opening in the outer shell 7 is preferably closed by a cap or module 32, 33, 35, 40 made at least partially from plastic.

[0054] To control the operation 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 can include a printed circuit board (PCB) to which the motor 11 is connected, while input / control means such as control switches, touchscreens, or other control elements can be connected to the PCB 30 or, more generally, to the electronic control unit.

[0055] As can be seen from FIGS. 3 to 5, the elongated handle 3 may include a substantially hollow housing 5, within which the aforementioned functional components 9 can be received and accommodated. The housing 5 of the handle 3 can include a metal shell 7 that at least partially forms the outer surface of the handle 3.

[0056] The functional components 9 received within the handle 3 may be pre-assembled to form a pre-assembled mounting unit. For example, the functional elements 9 may be pre-attached to a chassis element 31 which may be made at least partly, for example, from plastic. The aforementioned chassis element 31 may also include the aforementioned printed circuit board 30 on which other elements such as a motor, a battery, or a control switch, or a display, etc. may be mounted or connected.

[0057] As shown in FIGS. 3 to 5, the functional elements 9 may be grouped differently in a pre-assembled mounting module. According to an advantageous aspect, the personal care device 1 may be configured to have an elongated internal functional module 29 which may be inserted into the handle 3 through an opening at one of the axial ends of the housing 5. For example, a front-end opening 19 (see FIG. 6) may be provided at the axial upper end of the handle 3 facing the functional head 4, through which the elongated internal functional module 29 may be inserted into the handle 3. The elongated internal functional module 29 may include, for example, a motor 11, a battery 28, and 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 configuration that protects the electronic components as well as the motor and the battery from moisture and water.

[0058] The internal functional module 29 may also include a transmission device 12 for transmitting the driving movement of the motor 11 to the treatment tool 13 of the functional head 4, and a part of the transmission device 12 may project from the axial upper end of the handle 3 into or towards the functional head 4.

[0059] As can be seen from FIGS. 3 to 5, the front module 32 and / or the back module 33 may be attached to the lateral sides of the handle 3, and such front module 32 and / or back module 33 may also be connected to the internal functional components 9 received inside the handle 3. In order to enable connecting the front module 32 and the back module 33 to the internal components, the housing 5 of the handle 3, more specifically its external metal shell 7, may be provided with lateral notches or openings 21, 22 through which the front module 32 and the back module 33 may at least partially extend.

[0060] The front module 32 and the back module 33 may include electronic components and / or electrical components and / or mechanical components and / or tools, and the front module 32 and the back module 33 may include parts made of plastic and / or parts made of materials other than metal such as glass, although 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 for displaying control information such as treatment time or battery charge state. In addition or alternatively, the front module 32 may also include control elements such as control switches and / or output elements such as sound generators or speakers.

[0061] The back module 33 may include, for example, a battery module that may be configured to be replaceable. Such an additional battery module may be provided, for example, in addition to the battery 28 received inside the handle 3 so as to have a range extender, or such an additional battery module may be replaced with the battery 28 inside the handle 3. In addition or alternatively, the back module 33 may include other functional components 9 such as a special treatment tool 13. In the case of the shaver 2 or the hair clipper, such a special treatment tool 13 may include a long hair clipper.

[0062] As can be seen from FIGS. 3 to 5, the bottom module 35 may be attached to the handle 3 at the axial end opposite to the functional head 4. The handle 3, more specifically its housing 5, and more specifically the metal shell 7 of the handle housing 5 may be provided with a front opening 19 into which the bottom module 35 can be at least partially inserted. Such a bottom module 35 may be at least partially made of plastic and / or may include electronic components such as connection terminals for connecting supply cables and / or for connecting charger pins or charger connectors of a charger station. The bottom module 35 may also include a data connection terminal for connecting the personal care device 1 to a data transmission / reception station.

[0063] The top module 34 may be formed by the aforementioned functional head 4. Such a top module 34 may be permanently or removably attached to the upper end of the handle 3. More specifically, the base of the top module 34, which can support the body of the functional head 4 and / or the functional components 9, may be at least partially inserted into the hollow housing 5 of the handle 3 and / or may be attached to the axial end of the handle 3. More specifically, the base portion of the top module 34 may be attached to the metal shell 6 of the handle 3 in order to connect the functional components 9 of the functional head 4 to the functional components 9 of the handle 3. The top module 34 may be firmly attached to the metal shell 7 of the handle 3. Such a firm attachment may be fixed or releasable (see FIGS. 3, 4, and 5).

[0064] As can be seen from FIG. 7, at least one of the aforementioned functional modules 29, 32 to 35 may be inserted into the respective notches or openings 19, 20 or 21 of the metal shell 7 or the handle 3, whereby at least one module 29, 32 to 35 partially extends inside and partially outside the housing 5 of the handle 3, and more specifically, it may be configured to partially extend inside and partially outside the metal shell 7. More specifically, at least one of the modules 29, 32 to 35 may be configured to have a protrusion 25 extending through the corresponding openings 19, 20, 21 in the metal shell 7, and the outer portion of the protrusion 25 protrudes towards the outside of the handle 3 beyond the outer surface of the metal shell 7 (see sub - figure (b) of FIG. 7).

[0065] For example, at the interface between the metal shell 7 and the functional module, the above - mentioned protrusion 25 may protrude beyond the outer surface of the metal shell 7 by an amount in the range of 0.05 - 1 mm or 0.1 - 0.5 mm, or 0.1 - 0.3 mm. Such protrusions form a kind of protector that protects the skin and fingers from contacting the edges of the openings 19, 20 and 21.

[0066] However, instead, the functional modules 32 to 35 may be inserted flush into the corresponding openings 19, 20, 21 such that the aforementioned protrusion amount is substantially 0, and for example, it is also possible to have a slight negative protrusion amount of - 0.1 to - 0.5 mm.

[0067] As can be seen from FIG. 7(b), at least one of the functional modules 29, 32 to 35 may fit precisely into the corresponding openings 19, 20 and 21, and the outer peripheral surfaces of the modules 32 to 35 may conform to the corresponding openings 19, 20, 21 in terms of shape and dimensions. More specifically, the aforementioned protrusions 25 extending through the openings have a peripheral shape adapted to the contours of the respective openings 19, 20, 21 to achieve a precise fit between them or to enable sealing between them.

[0068] As can be seen from FIG. 7(b), the protrusion 25 may basically have a cylindrical shape, and thus, the outer portion of the protrusion 25 may extend substantially perpendicular or transversely to the outer surface of the metal shell 7. Alternatively, the protrusion 25 may include a collar 26 having a diameter or dimension or extension that is slightly larger than the portion of the protrusion that seats within the openings 19, 20, 21. Such a collar 26 can be seated on the outer surface of the metal shell 7.

[0069] The aforementioned protrusions 25 of the corresponding functional modules 29, 32 - 35 seated within the respective openings 19, 20, and 21 may be at least partially formed from plastic, and such plastic may be, for example, rigid plastic or soft plastic or a mixture thereof so as to snap - fit each module into the corresponding opening and seal the interface between the module attached to the metal shell 7.

[0070] As can be seen from FIGS. 11 - 13, the functional head 4 may have a configuration similar to that of the functional - head housing 6 and the functional modules or functional components 9 attached thereto. In particular, the functional component 9 or a group of functional components 9 may be at least partially inserted inside the housing 6 of the functional head 4. More specifically, the functional component 9 may include a protrusion 25 that protrudes outside beyond the outer surface of the metal shell 8 of the head housing 6, and the amount of protrusion (see FIG. 13) may be in the range of 0.05 - 1 mm, 0.1 - 0.5 mm, or 0.1 - 0.3 mm. Also in this case, as described for the functional modules of the handle 3, there is no height difference or basically a negative height difference to achieve a flush configuration.

[0071] The protrusions 25 of the chassis elements attached to the functional head 4 may also be at least partially formed from plastic, and such plastic may be rigid plastic and / or soft plastic to achieve snap - fitting and / or sealing.

[0072] 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 production of the metal shells 7, 8 may include a hydroforming process that includes applying a high-pressure working fluid to the inner surface of the metal shell blank 14, as shown in more detail in FIGS. 8 and 9.

[0073] Referring to FIG. 8, first, a metal shell blank 14, which may initially have a tubular shape, is inserted into an open mold 15 that, when closed, may define a cavity corresponding to the desired shape on the outside of the metal shells 7, 8. As can be seen from FIG. 8a, the metal shell blank 14 may be inserted such that the opposing edges of the tubular blank 14 reach the opposing edges of the mold 15 at the interface of the two mold parts. The ends of the tubular metal shell blank 14 should be accessible from the outside of the mold 15 to enable the supply of the working fluid into the interior of the tubular metal shell blank 14. Further, a pusher element 37 should be able to contact both ends of the tubular metal shell blank 14 to apply an axial compressive force.

[0074] When the mold 15 is closed (see FIG. 8b), the fluid supply connector is connected to the end of the tubular metal shell blank 14 and / or the pusher element 37 is placed at the said end of the tubular metal shell blank 14, the working fluid is injected into the interior of the tubular metal shell blank 14 through the open axial end of the tubular metal shell blank 14 to completely fill the interior of the metal shell blank 14 (see FIG. 8c).

[0075] Next, the hydraulic pressure is increased to achieve the radial expansion of the metal shell blank 14, more specifically, to press the metal shell blank 14 against the mold surface that defines the cavity of the mold 15 so that the metal shell blank 14 can take the shape of the mold cavity (see FIG. 8d).

[0076] Before, during, and / or after the metal shell blank 14 expands radially by hydraulic pressure, the aforementioned pusher 37 can be actuated to apply an axial compressive force to the metal shell blank 14. More specifically, the pusher element 37 may be pressed against both ends of the tubular metal shell blank 14 (see FIG. 8d) to support the desired deformation of the material of the metal shell blank 14.

[0077] The axial compressive force may be applied when the metal shell blank 14 is within the mold 15.

[0078] FIGS. 9a and 9b show 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 may be formed in a single hydroforming or hydraulic forming process (see FIG. 9b), and the mold 15 may be configured to achieve the hydroforming or hydraulic forming of a pair of outer metal shells 7, 8 oriented opposite to each other. As can be seen from FIG. 9b, for example, the two metal shells 7, 8 may face each other at their thicker ends, while the thinner ends may face away from each other, and the two metal shells may be arranged substantially coaxially with each other about their main axes.

[0079] After the hydroforming process, the metal shell or pair of metal shells may be removed from the mold and one or more cutting processes may be performed. In particular, the axial ends of the formed metal shells 7, 8 may be cut (see FIG. 9c). Such cutting processes may include different cutting techniques such as laser cutting, sawing, and / or milling.

[0080] As is apparent from FIG. 9c, the aforementioned front openings 19, 20 at the axial ends of the metal shells 7, 8 are created by cutting the ends in this way.

[0081] As shown in FIG. 9d, one or more lateral openings 21 are also cut into the metal shells 7, 8, enabling attachment of the aforementioned front module 32 and back module 33. It should be noted that other lateral openings can also be cut into the lateral sides of the outer metal shells 7, 8. For example, the perforations may be cut or drilled so as to allow visual contact with components within the metal shell such as a display or LEDs.

[0082] As shown in FIG. 10, the creation of the openings 19, 20, 21 or notches can be carried out by different methods and different cutting techniques. For example, as shown by FIG. 10a, the opening can have a sharp edge and / or an edge profile with a substantially cylindrical configuration as a parallel extension of all sections of the cut edge. Such a configuration can be achieved, for example, by drilling a hole or by moving another cutting tool such as a saw or a milling tool in a fixed orientation with respect to the metal shells 7, 8. For example, the metal shells 7, 8 may 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 machine the desired cutout profile.

[0083] Alternatively, as shown by FIG. 10b, the opening or notch may be manufactured by 3D cutting, and the orientation of the cutting tool is adjusted or changed along the displacement path of the cutting tool such that the edges of the resulting opening have different orientations in different sectors of the opening.

[0084] More specifically, such 3D cutting may be configured to adjust the orientation of the cutting tool relative to the inclination, orientation, and / or gradient of the outer surface of the metal shell section where the cutting is performed. More specifically, the orientation of the 3D cutting tool can be adjusted such that the edge of the resulting opening is substantially perpendicular to the outer surface of the metal shell adjacent to or surrounding the opening (see FIG. 10b), and such an outer surface adjacent to the opening can change its orientation along the opening and / or can have a curved shape such as a barrel shape, or can have a multi-axis curved profile. Thereby, sharp edges on the outside of the metal shell are avoided. "Substantially perpendicular" in this context means that the angle between the outside of the outer shell and the edge side of the opening is within the range of 70 to 120 degrees, more preferably within the range of 80 to 100 degrees.

[0085] For example, such 3D cutting may include laser cutting by a laser cutter that can pivot about two or three axes, and the translational displacement of the laser relative to the metal shell may be achieved by the translation of the fixture holding the metal shell during the cutting process and / or the translation of the laser cutter. It is also possible to achieve 3D cutting by rotating the fixture holding the metal shell and adapt the orientation of the laser to the inclination or orientation of the metal shell surface.

[0086] Such 3D cutting may also use other cutting techniques such as milling or waterjet cutting.

[0087] As can be seen from FIG. 14, the hydroforming process for forming the metal shells 7, 8 may also include electrohydroforming, which is also known as EHF. Such electrohydroforming is based on the ultra-high speed deformation of a metal shell blank using shock waves or pressure waves in a working fluid such as water. Through a discharge current, an electric arc can be generated in water between at least a pair of electrodes. Such an electric arc evaporates the surrounding water and / or working fluid and converts electrical energy into a high-pressure wave of mechanical energy. Such a shock wave simultaneously converts the metal shell blank 14 into a viscoplastic state, presses and / or accelerates the metal shell blank 14 onto the surface of the mold cavity, thereby enabling the formation of a desired shape at high speed under low-temperature conditions. Such electrohydroforming can form particularly complex shapes.

[0088] As shown in FIG. 15, the forming process for forming the outer metal shells 7, 8 into a desired shape may use electromagnetic forming, which is known as EMF. Such electromagnetic forming is based on the ultra-high speed deformation of a metal using a magnetic field. For example, through a discharge current in a coil, a magnetic field is generated, which simultaneously converts the metal shell blank into a viscoplastic state and presses / accelerates the metal shell blank onto the surface of the mold cavity, thereby enabling the metal shell to be formed into a desired shape at high speed under low-temperature conditions. Also, such electromagnetic forming can form complex shapes.

[0089] The dimensions and values disclosed in this specification should not be understood as being strictly limited to the exact numerical values recited. Instead, unless otherwise specified, each such dimension is intended to mean both the recited value and a functionally equivalent range surrounding that value. For example, a dimension disclosed as "40 mm" is intended to mean "about 40 mm".

Claims

1. A method of manufacturing a hair cutter having an external metal shell, comprising: forming the external metal shell (7, 8) into one integral part having a desired shape, a homogeneous seamless structure, and a hollow elongated closed ring or closed sleeve shape; the forming step includes placing a hollow, sleeve-shaped or pipe-shaped metal shell blank (14) into a cavity of a mold (15) surrounding the outside of the metal shell blank (14), applying hydraulic pressure inside 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), thereby causing the outside of the metal shell blank (14) to take the shape of the contour of the mold (15); in the formed external metal shell, making front openings (19, 20) at opposite axial ends, and preferably forming at least one lateral opening or perforation in the middle side part; attaching functional components (9) and / or modules for performing or assisting in performing personal care functions in and / or on the formed external metal shell (7, 8).

2. The hydraulic forming step is a hydroforming step, wherein the metal shell blank (14) and / or the mold (15) in the mold (15) is filled with a working fluid such as water, and pressure is applied to the working fluid from a pressure source outside the mold (15). The method according to claim 1.

3. The hydraulic forming step is an electro-hydraulic forming step, wherein the metal shell blank (14) is placed in a working fluid reservoir in which one or more pressure waves are generated by at least one pair of electrodes, and the one or more pressure waves form the metal shell blank (14) into the desired shape of the external metal shell (7, 8). The method according to claim 1.

4. The external metal shell (7, 8) is formed to have at least one undercut portion by the hydraulic pressure. The method according to any one of claims 1 to 3.

5. The external metal shell (7, 8) is formed with the axial ends having a closed annular cross-section surrounding the openings (19, 20). The method according to any one of claims 1 to 4.

6. The method according to any one of claims 1 to 5, wherein the external metal shell (7, 8) is formed with an intermediate section (16) between the opposing ends (17, 18) that includes at least two lateral openings and / or lateral perforations for accessing or connecting to the functional component (9) housed inside or outside the external metal shell (7, 8).

7. The method according to claim 6, wherein the functional component (9) or module includes at least three, four, five, or all of the following: a drive unit, a charging connector provided at the lower end, a charging connector provided in the lateral opening, a display provided in the lateral opening, a hair cutting tool provided at the upper end, and / or a special treatment tool provided on the lateral side or the lower end of the external metal shell.

8. The method according to claim 7, wherein the external metal shell (7, 8) is formed to have a preferably expanded intermediate portion that defines the maximum cross-sectional area of the external metal shell (7, 8), and two opposing ends (17, 18) that each define a front opening (19, 20) and have a cross-sectional area smaller than the maximum cross-sectional area defined by the preferably expanded intermediate portion (16).

9. The method according to any one of claims 1 to 8, wherein the metal shell blank (14) is subjected to an axial compressive force within the mold (15) before, during, and / or after the application of the hydraulic pressure, facilitating the transverse deformation of the metal shell blank (14).

10. The method according to claim 9, wherein the axial compressive force is applied to the opposing ends of the metal shell blank (14) at least partially temporally overlapping with the application of the hydraulic pressure.

11. The method according to claim 9 or 10, wherein the axial compressive force is applied to the end of the metal shell blank (14) extending outside the mold cavity by a pusher (37) disposed outside the mold (15) and movable relative to the mold (15).

12. At least one opening (19, 20, 21) having a three-dimensional edge contour (22) is cut into the external metal shell (7, 8) in the 3D cutting process, and the three-dimensional edge contour (22) is adjacent to and surrounds the opening (19, 20, 21) along the entire contour of the opening (19, 20, 21). It is substantially perpendicular to the outer shell portion of the external metal shell (7, 8), or is in the range of 70 to 110 degrees, and the shell portion adjacent to and surrounding the opening (19, 20, 21) has various orientations that vary along the opening (19, 20, 21). The method according to any one of claims 1 to 11.

13. The method according to claim 12, wherein the 3D cutting process includes laser cutting.

14. At least one surface treatment process including at least one of the following processes: brushing, shot blasting, grit blasting, ball peening, coating, plating, varnishing, and chemical edging is applied to the external metal shell (7, 8) after the hydroforming process. The method according to any one of claims 1 to 13.

15. The metal shell blank (14) is made of stainless steel, or steel containing chromium, nickel, and molybdenum, particularly 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. The method according to any one of claims 1 to 14.

16. Producing two or more outer shells using one metal shell blank includes the forming process and cutting the formed part into two or more outer shell pieces. The method according to any one of claims 1 to 15.

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