Method of manufacturing a protective element for use in a hair cutting unit

Abstract

In a method for manufacturing a protective element (21), the protective element (21) being configured for use in a hair cutting unit and the design of the protective element (21) comprising a shaving track (30) having a plurality of hair entry holes (34), the shaving track (30) having a thickness profile having at least one thickness value, a plurality of steps are performed in a certain order. In an initial step, a sheet is provided. In a first subsequent step, at a location in the sheet where the shaving track (30) is to be formed, at least one thickness value of the thickness profile of the shaving track (30) according to the design of the protective element (21) is achieved. In a second subsequent step, material is removed from the sheet at the location where the shaving track (30) is to be formed to create the hair entry holes (34).

Description

Technical Field

[0001] The invention relates to a method for manufacturing a guard element which is configured to be used in a hair cutting unit as a shield for a movable hair cutting element of the hair cutting unit and whose design comprises a shaving track with a plurality of hair entry apertures.

[0002] Furthermore, the present invention relates to a method for manufacturing a hair cutting unit comprising a protective element and a movable hair cutting element, the movable hair cutting element being at least partially arranged in an inner space of the protective element, and also to a method for manufacturing a hair cutting appliance comprising a body for holding by a user of the hair cutting appliance and a head, the head comprising at least one hair cutting unit. Background Art

[0003] The present invention belongs to the field of hair cutting instruments, in particular to hair cutting instruments designed to perform shaving actions, etc., in which hair is cut at a position close to the skin. Usually, the hair cutting instrument comprises a head, and one or more hair cutting units are located at the head. The hair cutting units of three equilateral triangle configurations are used in a particularly common design. Each hair cutting unit comprises a movable hair cutting element and a protective element. The protective element is provided with a series of hair entry holes. For example, in practical situations, the protective element is cup-shaped normally and has a substantially circular periphery, and the hair entry hole can be shaped like an elongated groove, which extends substantially radially relative to the central axis of the protective element in one or more annular regions called shaving tracks.

[0004] The protective element has an outer surface for contacting the skin at the position of (multiple) shaving tracks during the hair cutting action and an inner surface contacted by the hair cutting element at the position of (multiple) shaving tracks. At the position where the hair entry hole is limited, there is a cutting surface in the protective element. The hair cutting element includes a blade with a cutting edge. During the hair cutting action, the hair entering the hair entry hole is trimmed between the cutting surface and the cutting edge, and is therefore cut. Correct use of the hair cutting utensil includes placing the utensil in an active state, i.e., a state in which the hair cutting element of at least one hair cutting unit is moved, and moving the head to the skin area where the hair cutting action is to be performed.

[0005] JP H08 141228 A discloses a method for manufacturing a protective element, which is configured to be used as an external hair cutting element of an electric shaving device. The external hair cutting element has a plurality of slit-shaped hair entry openings arranged in an annular shaving track of the external hair cutting element. In a first series of manufacturing steps, a plate is stamped and pressed to form a disk, and the disk is stretched and pressed to present a three-dimensional shape with the annular shaving track. In a second manufacturing step, the thickness of the annular shaving track is reduced by removing material from the inner surface of the annular shaving track. In a third manufacturing step, a hair entry opening is formed in the annular shaving track by a milling process. In a fourth manufacturing step, the inner and outer surfaces of the annular shaving track are processed by a polishing process.

[0006] As mentioned above, hair cutting appliances are usually mass-produced. In view of this, people have always wished to simplify the manufacturing process of the various components of hair cutting appliances, including the protective element and the hair cutting element of the hair cutting unit, thereby saving manufacturing costs and possibly also obtaining other benefits. Summary of the invention

[0007] In view of the foregoing, the present invention provides a method for manufacturing a protective element, which is configured to be used as a shield for a movable hair cutting element of a hair cutting unit in a hair cutting unit, and the design of the protective element includes a shaving track with multiple hair entry holes, the shaving track having a thickness profile, the thickness profile having at least one thickness value, the method comprising an initial step of providing a sheet, from which the protective element will be formed, and the method comprising a step intended to create a shaving track in the sheet according to the design of the protective element, including a thickness adjustment step and a material removal step, wherein the thickness adjustment step is to achieve at least one thickness value of the thickness profile of the shaving track in the sheet according to the design of the protective element at the position where the shaving track is to be formed, and the material removal step is to remove material from the sheet at the position where the shaving track is to be formed to form the hair entry holes, wherein the thickness adjustment step is performed earlier than the material removal step.

[0008] According to the above definition, in the manufacturing process of the protective element according to the invention, before the hair entry hole is formed, a step has been performed which is intended to provide the shaving track with a thickness profile according to the design of the protective element. As a result, when the invention is put into practice, it is achieved that for a near-final product already provided with the hair entry hole, no thickness adjustment action is required as a finishing action. In this way, the invention provides a manufacturing method which can include fewer steps than conventional manufacturing methods, according to which a thickness adjustment is always (in addition) performed after the hair entry hole has been formed. Moreover, it has been found that, in the context of the present invention, only for the purpose of achieving a thickness profile of the shaving track, it is possible to rely on cold forming techniques, whereas the art teaches that techniques such as grinding or polishing must be applied after cold forming.

[0009] The material removal step by which the hair entry aperture is formed may comprise any suitable action.For example, as is generally known in the art of hair cutting appliances, a cutting action such as stamping may be performed on the sheet material.

[0010] It may be that in the design of the guard element the thickness profile of the shaving track has different thickness values ​​at different areas of the shaving track, although this is not necessary in the context of the present invention. Practically, when putting the present invention into practice, any thickness profile of the shaving track may be achieved, including a thickness profile having only a single thickness value, in which case the shaving track has substantially the same thickness in each of its areas. In the case where different thickness values ​​are to be achieved for different areas of the shaving track, it may be that one thickness value is obtained by actively reducing an initial thickness value, while another thickness value has been found in the sheet from which the guard element is to be formed in an initial step of providing the sheet. In other words, it may be that different thickness values ​​are created by a thickness-reducing action on one area of ​​the sheet located at the location of one area of ​​the shaving track, while another area of ​​the sheet located at the location of another area of ​​the shaving track is left intact.

[0011] According to the foregoing, the thickness adjustment step may in particular comprise the practical action of reducing the thickness of the sheet material at the location of at least one area where the shaving track is to be formed. In this regard, it is noted that the thickness adjustment step may comprise the action of cold forming the sheet material at the location of at least one area where the shaving track is to be formed. For example, the thickness adjustment step may comprise the action of applying pressure to the sheet material and / or flattening the sheet material at the location of at least one area where the shaving track is to be formed. For the sake of clarity, it is noted that performing the thickness adjustment step may comprise a plurality of actions, which may comprise the cold forming action as described above, but may also comprise material removal actions such as grinding and / or polishing.

[0012] The method according to the invention can be used for the purpose of manufacturing a guard element having a design according to which the shaving track is annular with respect to the central axis of the guard element. In this case, the method can include at least one of the following steps: an external bending step of bending the sheet material at the location of the outer peripheral edge of the annular portion of the sheet material to form the shaving track, and an internal bending step of bending the sheet material at the location of the inner peripheral edge of the annular portion of the sheet material to form the shaving track, wherein both the thickness adjustment step and the material removal step are performed earlier than at least one of the external bending step and the internal bending step. It is generally known that in order to effectively capture the hairs to be cut, it is advantageous if the outer surface of the guard element is convexly curved at the location of at least the outer peripheral edge of the shaving track and there is a run-in portion of the hair entry hole in at least the outer peripheral edge of the shaving track. Furthermore, the guard element may be designed in such a way that the shaving track has a generally elevated position on the guard element, so that during use of a hair cutting appliance having one or more hair cutting units in which the guard element is comprised, the skin area on which the hair cutting action is to be performed is practically contacted by the guard element only at the location of the shaving track, in which case it is practical to have the outer surface of the guard element convexly curved both at the location of the outer peripheral edge of the shaving track and at the location of the inner peripheral edge of the shaving track.

[0013] By applying the invention, any feasible thickness profile of the shaving track can be achieved. For example, it can be as follows: during the thickness adjustment step, a thickness distribution is achieved in the sheet in which the thickness value at the location of the relatively thick area of ​​one part of the sheet to form the shaving track is at least twice the thickness value at the location of the relatively thin area of ​​another part of the sheet to form the shaving track, but this does not change the fact that the invention is also suitable for the following purposes: achieving a thickness profile of the shaving track in which the difference between the relatively thick area of ​​the shaving track and the relatively thin area of ​​the shaving track is smaller, or achieving a constant thickness profile of the shaving track, which constant thickness profile does not require the achievement of a thickness distribution in the sheet. In any case, it is practical that the sheet provided in the initial step is a sheet with a substantially uniform thickness, although the invention also covers the option of providing a sheet with a certain initial thickness distribution, which initial thickness distribution is converted into another thickness distribution in the thickness adjustment step. In addition, with regard to the sheet, it is noted that the sheet can initially be of planar shape, but this is not necessary within the framework of the invention.

[0014] According to a practical option, the guard element has a design according to which the shaving track is annular about the central axis of the guard element, wherein between the hair entry holes there is a further elongated sheet (lamellae) having a thickness distribution in which the thickness value at the outer end portion of the respective sheet is greater than the thickness value at the main portion of the respective sheet. In this case, it is advantageous if the thickness adjustment step comprises implementing the thickness values ​​of the thickness distribution of the sheet in the sheet according to the design of the guard element at the location where the shaving track is to be formed, the thickness value of the outer end portion of the respective sheet being implemented at the annular portion of the sheet to form the outer end portion of the respective sheet, and the thickness value of the main portion of the respective sheet being implemented at the annular portion of the sheet to form the main portion of the respective sheet. For example, in the thickness adjustment step, a flattening action can be performed on the sheet at the location of the annular portion of the sheet to form the main portion of the respective sheet, while no thinning action is performed at the location of the annular portion of the sheet to form the outer end portion of the respective sheet.

[0015] According to what has been suggested previously, after both the thickness adjustment step and the material removal step have been carried out, the action of bending the sheet material can be performed at the location where the outer end portion of the respective sheet is to be formed. Furthermore, it can be as follows: in the design of the protective element, the thickness value at the inner end portion of the respective sheet is also greater than the thickness value at the main part of the respective sheet, in which case it is practical if the thickness value at the inner end portion of the respective sheet is achieved during the thickness adjustment step at the annular portion of the sheet material that is to form the inner end portion of the respective sheet. It can be as follows: the thickness value of the outer end portion of the respective sheet and the thickness value of the inner end portion of the respective sheet are each at least twice the thickness value of the main part of the respective sheet, but other relationships of the various thickness values ​​are also possible.

[0016] The method according to the invention may further comprise a shaving track bulging step, which comprises providing at least one area of ​​the shaving track with an outwardly bulged shape. Providing at least one area of ​​the shaving track with an outwardly bulged shape is believed to be advantageous for improving the comfort of the user and also for improving the effectiveness of the hair cutting action by better fitting the user's skin while reducing the bulging effect. The shaving track bulging step may be performed after the material removal step, but this is not necessary within the framework of the invention.

[0017] In view of the foregoing, it is noted that an example of a protective element is known from WO 2013 / 104965 A1, which comprises a sheet having a thicker end portion and a thinner main portion. In this respect, WO 2013 / 104965 A1 discloses that the total thickness of the protective element and the shaving track can be approximately 70-150 microns, while the main portion of the shaving track can have a thickness of 60 microns or less. The protective element is intended to be used in a shaving appliance, and the thickness profile of the shaving track is selected to have an increased shaving tightness while preventing an increased risk of skin entering the hair entry hole. Moreover, WO 2013 / 104965 A1 discloses the possibility of having a dome-shaped outer surface of the shaving track.

[0018] The invention further relates to a method for manufacturing a hair cutting unit, the hair cutting unit comprising a protective element and a movable hair cutting element, the movable hair cutting element being at least partially arranged in the inner space of the protective element, wherein the protective element is manufactured by the method mentioned above in this document. In addition, the invention relates to a method for manufacturing a hair cutting appliance, the hair cutting appliance comprising a body for a user of the hair cutting appliance to hold and a head, the head comprising at least one hair cutting unit, wherein the hair cutting unit is manufactured by the method mentioned above in this document.

[0019] The above and other aspects of the invention are apparent from and will be elucidated by reference to the following detailed description of a guard element for use in a hair cutting unit of a hair cutting appliance, in particular a shaving appliance, and the steps of a method of manufacturing such a guard element. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present invention will now be explained in more detail with reference to the accompanying drawings, in which the same or similar parts are indicated by the same reference numerals, and in which:

[0021] Figure 1 schematically shows a perspective view of a hair cutting appliance manufactured by the method according to the invention;

[0022] Figure 2 schematically shows a perspective view of a guard element of a hair cutting unit of a hair cutting appliance;

[0023] Figure 3 schematically shows a cross-sectional view of a portion of a guard element;

[0024] Figure 4 yes Figure 3 and a cross-sectional view of the shaving track showing the guard element; and

[0025] Figure 5-9Various steps of a method for manufacturing a guard element are shown, in particular steps aimed at producing a shaving track of the guard element. DETAILED DESCRIPTION

[0026] Figure 1 The invention relates to a hair cutting appliance manufactured by a method according to the invention. In the figure, a shaving appliance 1 is shown, which comprises a body 11 and a head 12. The head 12 can be removably or hingedly mounted to the body 11. The body 11 of the shaving appliance 1 is also often referred to as a handle. In the example shown, three hair cutting units 20 are arranged in the head 12, which does not change the fact that another number of hair cutting units 20 can be selected, ranging from one to more than three.

[0027] Figures 2 to 4 A protective element 21 is concerned, which, in addition to a hair cutting element (not shown in the figure), is part of a hair cutting unit 20. The shaving appliance 1 shown is rotatable, which means that the hair cutting element is arranged to be rotatable in the hair cutting unit 20. For the sake of clarity, it is noted that the possible application of the present invention is not limited to the context of appliances comprising one or more rotatable hair cutting elements. Moreover, it is noted that the protective element 21 to be described now is only one of many embodiments covered by the present invention, and design details of this particular protective element 21 that are not within the basic definition of protective elements provided in the claims should not be understood as limiting the present invention, wherein it is also noted that details that can be considered independently by a skilled person should not be understood as being closely related, even if these details are disclosed with reference to a single example, unless an indication to the contrary is clearly given.

[0028] The guard element 21 has a generally cup-shaped design with a substantially circular periphery, a central axis 22 and an outer surface 23. The guard element 21 is provided with an annular shaving track 30 for contacting the user's skin during a shaving action, the shaving track 30 having two concentrically arranged peripheral edges 31, 32, namely an outer peripheral edge 31 and an inner peripheral edge 32. The guard element 21 further comprises a sheet 33 extending along the entire width of the shaving track 30 between the peripheral edges 31, 32 in a substantially radial direction relative to the central axis 22 of the guard element 21. Each sheet 33 has an outer end portion 33a at the location of the outer peripheral edge 31 of the shaving track 30, an inner end portion 33b at the location of the inner peripheral edge 32 of the shaving track 30, and a main portion 33c at an intermediate position between the end portions 33a, 33b. The holes present between the sheets 33 constitute the hair entry holes 34 of the shaving track 30. The side surfaces of the sheet 33 constitute cutting surfaces adapted to sever hairs in cooperation with the cutting edges of the hair cutting elements.

[0029] When each of the hair cutting elements of the hair cutting unit 20 is actuated to rotate and the head 12 of the shaving apparatus 1 is moved to the skin area from which the hair protrudes, the hair cutting action is performed. In this process, the skin area is actually contacted by the protective element 21 of the corresponding hair cutting unit 20. In each protective element 21, the contact between the skin and the protective element 21 is established at the position of the shaving track 30. During the movement of the head 12 of the shaving apparatus 1 to the skin area, the hair protruding from the skin area is captured in the hair entry hole 34 of the protective element 21, and, due to the cooperation between the cutting surface on the side of the sheet 33 defining the hair entry hole 34 and the cutting edge of the rotating hair cutting element, the hair is cut off at this position.

[0030] In the example shown, the outer surface 23 of the guard element 21 is slightly domed or toroidal in shape at the location of the shaving track 30. However, it is to be understood that the present invention is equally applicable to environments where the outer surface 23 of the guard element 21 is planar or has other shapes other than domed or toroidal at the location of the shaving track 30. Furthermore, in the example shown, the inner surface 24 of the guard element 21 is also domed in shape at the location of the shaving track 30. Figure 3 and Figure 4 As can be seen in the figure, the curvature of the inner surface 24 of the guard element 21 at the location of the shaving track 30 is different from the curvature of the outer surface 23 of the guard element 21 at the same location, and therefore the thickness profile of the shaving track 30 has different thickness values, wherein the lowest thickness value applies to the annular area where the main part 33c of the respective sheet 33 of the shaving track 30 is located, and wherein the highest thickness value applies to the annular area where the respective end parts 33a, 33b of the respective sheet 33 of the shaving track 30 are located. For example, the first thickness value may be 100 microns or less, while the latter thickness value may be much larger, at least twice as large, such as about 200 microns.

[0031] According to the invention, the production of a shaving track 30 having a thickness profile as described above comprises a specific sequence of steps, as will now be referred to. Figure 5-9 Described.

[0032] Figure 5 Referring to an initial step, there is schematically shown a cross-sectional view of a portion of a sheet 40 which is provided in this step for forming a guard element 21. The portion of the sheet shown is the portion of the shaving track 30 in which the guard element 21 is to be formed. In the example shown, the sheet 40 is initially planar and has a constant thickness.

[0033] Figures 6 to 9It shows how the portion of the plate 40 is transformed into the shaving track 30. Each figure shows a cross-sectional view of the plate 40 / shaving track 30 during manufacture, wherein it is noted that such a figure represents what occurs along the entire annular area of ​​the plate 40 / shaving track 30 during manufacture.

[0034] Figure 6 involves the first subsequent step and from Figure 6 and Figure 5 A comparison of , results in that the first subsequent step consists in achieving a thickness reduction in the annular portion of the sheet 40 that is to form the main portion 33c of the corresponding sheet 33. This thickness reduction may be achieved in any suitable manner, such as by applying a cold forming technique.

[0035] Figure 7 Referring to the second subsequent step, this step comprises forming the hair entry hole 34, which can be accomplished in various ways by any suitable technique suitable for removing material from the sheet 40 at the appropriate location, which technique can be a cutting technique, such as punching, as suggested earlier. The end of the hair entry hole 34 is at Figure 7 is schematically shown by a dotted line in Figure 8 and Fig. 9 It is also schematically shown by dotted lines.

[0036] Figure 8 and Fig. 9 Referring to a third subsequent step, this step comprises bending the sheet material 40 at the location where the outer end portion 33a of the respective sheet 33 is to be formed, and bending the sheet material 40 at the location where the inner end portion 33b of the respective sheet 33 is to be formed. The two bending actions mentioned can be performed simultaneously or one after the other. Within the framework of the invention, it is also possible to perform a bending action only at the location of one of the outer end portion 33a and the inner end portion 33b of the respective sheet 33. It is to be understood that the exact nature of the third subsequent step is determined by the design of the protective element 21. On the other hand, depending on the design of the protective element 21, it may not be necessary to have a third subsequent step.

[0037] From the foregoing, it follows that the first subsequent step is a thickness adjustment step, aimed at creating a thickness profile of the shaving track 30 according to the design of the guard element 21 in the sheet 40, the second subsequent step is a material-removal step, aimed at creating the hair entry hole 34 of the shaving track 30, and the optional third subsequent step is a bending step, aimed at achieving a curvilinear appearance at one or both of the outer peripheral edge 31 of the shaving track 30 and the inner peripheral edge 32 of the shaving track 30. In view of the fact that the thickness profile of the shaving track 30 according to the design of the guard element 21 is achieved as a result of the execution of the first subsequent step, once the first subsequent step has been executed and the second subsequent step is initiated, no further specific thickness adjustment action needs to be performed, and therefore will not be done when applying the present invention. Therefore, according to the present invention, before forming the hair entry hole 34, (a) the thickness adjustment action(s) is first taken and completed. Any bending action mentioned above in relation to the third subsequent step does not occur earlier than the time when the thickness adjustment step and the material removal step occur.

[0038] The manufacturing process of the protective element 21 may include other steps in addition to the above-mentioned initial step, first subsequent step, second subsequent step and optional third subsequent step, which steps may be performed as intermediate steps and / or finishing steps in the process. The term "subsequent" as used herein with respect to steps should be understood to refer to subsequent steps, which are not necessarily the same as the steps that immediately follow the steps identified as earlier steps in the process. An example of a step that may be performed as a finishing step is a step intended to achieve an outwardly convex shape (i.e., dome-shaped or donut-shaped) of at least one area of ​​the shaving track 30, as previously described.

[0039] It will be clear to those skilled in the art that the scope of the present invention is not limited to the examples discussed above, and that several modifications and variations may be made thereto without departing from the scope of the present invention as defined in the appended claims. It is intended that the present invention be interpreted as including all such modifications and variations that fall within the scope of the claims or their equivalents. Although the present invention has been shown and described in detail in the drawings and the specification, such illustration and description should be considered to be merely illustrative or exemplary, and not restrictive. The present invention is not limited to the disclosed embodiments. The accompanying drawings are schematic, in which details not necessary for understanding the present invention may have been omitted, and are not necessarily drawn to scale.

[0040] By studying the drawings, the specification, and the appended claims, those skilled in the art can understand and implement other variations of the disclosed embodiments when practicing the claimed invention. In the claims, the word "comprising" does not exclude other steps or elements, and the indefinite article "a" or "an" does not exclude a plurality. Any reference numerals in the claims should not be interpreted as limiting the scope of the invention.

[0041] Unless expressly stated otherwise, elements and aspects discussed with respect to or in connection with a particular embodiment may be suitably combined with elements and aspects of other embodiments. Thus, the fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

[0042] As used herein, the terms "comprise" and "include" will be understood by those skilled in the art to encompass the term "consisting of." Thus, with respect to an embodiment, the terms "comprise" and "include" may mean "consisting of," but in another embodiment may mean "comprising / having / equipped with at least the defined species and optionally one or more other species."

[0043] The guard element 21 as described according to the figures comprises a single shaving track 30. This does not change the fact that the invention is also applicable to guard elements 21 comprising more than one shaving track, wherein the concept of taking all actions aimed at achieving the desired thickness profile of the shaving track before creating the hair entry holes 34 of the shaving track can be applied to one or more of these shaving tracks. In this regard, it is noted that examples of guard elements 21 comprising up to three shaving tracks are known from WO 2008 / 152590 A1.

[0044] Furthermore, it is not essential for the guard element 21 according to the invention to include more or less elongated sheets 33 extending all the way between the peripheral edges 31, 32 of the shaving track 30. For example, the following options are also covered by the invention: a shaving track 30 in which the hair entry holes 34 have a substantially circular shape, and a shaving track 30 in which a combination of longer sheets bridging over the entire width of the shaving track 30 and shorter sheets extending as teeth only along a portion of the width of the shaving track 30 is used. In general, where a sheet is included in the design of the shaving track 30, such a sheet may have any suitable shape and may, for example, include forks.

[0045] With regard to the proposal during the thickness adjustment step to achieve at least one thickness value of the thickness profile of the shaving track 30 in the sheet 40 at the location where the shaving track 30 is to be formed according to the design of the protective element 21, it is noted that this is to be understood in its practical sense and not in its theoretical sense, taking into account that in practice a tolerance window applies when it comes to achieving values.

[0046] The salient aspects of the invention can be summarized as follows. In a method for manufacturing a protective element 21, which is configured to be used in a hair cutting unit 20 as a shield for a movable hair cutting element of the hair cutting unit 20, and the design of the protective element 21 comprises a shaving track 30 with a plurality of hair entry holes 34, the thickness profile of the shaving track 30 having at least one thickness value, a plurality of steps are performed in a certain order. In an initial step, a sheet 40 is provided from which the protective element 21 is to be formed. In a first subsequent step, at the location in the sheet 40 where the shaving track 30 is to be formed, at least one thickness value of the thickness profile of the shaving track 30 is achieved according to the design of the protective element 21. In a second subsequent step, material is removed from the sheet 40 at the location where the shaving track 30 is to be formed to create the hair entry holes 34.

Claims

1. A method for manufacturing a protective element (21), the protective element (21) being configured to be used in a hair cutting unit (20) as a shield for a movable hair cutting element of the hair cutting unit (20), and the design of the protective element (21) comprising a shaving track (30) having a plurality of hair entry holes (34), the shaving track (30) having a thickness profile, the thickness profile having at least one thickness value, the method comprising an initial step of providing a plate (40) from which the protective element (21) is to be formed, and the method comprising the step of forming a protective element in the plate (40) according to the thickness of the plate (40). The step of creating the shaving track (30) by the design of the guard element (21) comprises a thickness adjustment step and a material removal step, wherein the thickness adjustment step is to realize at least one thickness value of the thickness profile of the shaving track (30) in the plate (40) according to the design of the guard element (21) at the position where the shaving track (30) is to be formed, and the material removal step is to remove material from the plate (40) at the position where the shaving track (30) is to be formed to form the hair entry hole (34), wherein the thickness adjustment step is performed earlier than the material removal step.

2. The method according to claim 1, wherein in the design of the guard element (21), the thickness profile of the shaving track (30) has different thickness values ​​at different areas of the shaving track (30).

3. The method according to claim 1 or 2, wherein the thickness adjustment step comprises reducing the thickness of the plate (40) at the location of at least one area where the shaving track (30) is to be formed.

4. The method according to any one of claims 1 to 3, wherein the thickness adjustment step comprises the act of cold forming the sheet (40) at the location of at least one area where the shaving track (30) is to be formed.

5. The method according to any one of claims 1 to 4, wherein the thickness adjustment step comprises an action of applying pressure to the plate (40) and / or flattening the plate (40) at the location of at least one area where the shaving track (30) is to be formed.

6. The method according to any one of claims 1 to 5, wherein in the design of the protective element (21), the shaving track (30) is annular with respect to the central axis (22) of the protective element (21), the method comprising at least one of the following steps: an external bending step of bending the plate (40) at a position of an outer peripheral edge (31) of the annular portion of the plate (40) to form the shaving track (30), and an internal bending step of bending the plate (40) at a position of an inner peripheral edge (32) of the annular portion of the plate (40) to form the shaving track (30), wherein both the thickness adjustment step and the material removal step are performed earlier than at least one of the external bending step and the internal bending step.

7. A method according to any one of claims 1 to 6, wherein during the thickness adjustment step, a thickness distribution is achieved in the plate (40), in which the thickness value at the position of a relatively thick area of ​​one part of the plate (40) where the shaving track (30) is to be formed is at least twice the thickness value at the position of a relatively thin area of ​​another part of the plate (40) where the shaving track (30) is to be formed.

8. The method according to any one of claims 1 to 5, wherein in the design of the guard element (21), the shaving track (30) is annular with respect to the central axis (22) of the guard element (21), and wherein between the hair entry holes (34) there are further elongated sheets (33), the sheets (33) having a thickness distribution in which the thickness values ​​at the outer end portions (33a) of the respective sheets (33) are greater than the thickness values ​​at the main portions (33c) of the respective sheets (33), wherein the thickness adjustment step comprises adjusting the thickness of the shaving track (30) in the process of forming the shaving track (30) to form the hair entry holes (34). At the position of the scraping track (30), the thickness value of the thickness distribution of the sheet (33) is realized in the plate (40) according to the design of the protective element (21), the thickness value of the outer end portion (33a) of the corresponding sheet (33) is realized at the annular portion of the plate (40) that is to form the outer end portion (33a) of the corresponding sheet (33), and the thickness value of the main portion (33c) of the corresponding sheet (33) is realized at the annular portion of the plate (40) that is to form the main portion (33c) of the corresponding sheet (33).

9. The method according to claim 8, wherein the plate material (40) is bent at a position where the outer end portion (33a) of the corresponding sheet (33) is to be formed after both the thickness adjustment step and the material removal step have been performed.

10. A method according to claim 8 or 9, wherein in the design of the protective element (21), the thickness value at the inner end portion (33b) of the corresponding sheet (33) is also greater than the thickness value at the main portion (33c) of the corresponding sheet (33), wherein during the thickness adjustment step, the thickness value at the inner end portion (33b) of the corresponding sheet (33) is achieved at the annular portion of the plate material (40) that is to form the inner end portion (33b) of the corresponding sheet (33).

11. Method according to any of claims 1-10, comprising a shaving track protruding step, said shaving track protruding step comprising providing at least one area of ​​the shaving track (30) with an outwardly protruding shape.

12. Method according to any one of claims 1 to 11, wherein the sheet (40) provided in the initial step is a sheet having a substantially uniform thickness.

13. Method according to any one of claims 1 to 12, wherein during the material removal step, a cutting action is performed on the sheet (40).

14. A method for manufacturing a hair cutting unit (20), the hair cutting unit (20) comprising a protective element (21) and a movable hair cutting element, the movable hair cutting element being at least partially arranged in an inner space of the protective element, characterized in that The protective element (21) is manufactured by the method according to any one of claims 1-13.

15. A method for manufacturing a hair cutting appliance (1), the hair cutting appliance (1) comprising a body (11) for a user of the hair cutting appliance to hold and a head (12), the head (12) comprising at least one hair cutting unit (20), characterized in that The hair cutting unit is manufactured by the method of claim 14 .

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