Method of curling hair

Abstract

The invention provides a method for curling hair comprising: providing a hair styling appliance (1) comprising a heatable mandrel (3) having a curling radius of between 2.5 and 7.5 mm, wrapping a hair strand (X) around the mandrel (3), and applying a curling stress of less than or equal to 0.25 MPa on the hair strand (X) wrapped around the mandrel (3).

Description

TECHNICAL FIELD

[0001] The present invention relates to a method for curling hair, and more particularly to a thermo-mechanical method for curling hair. BACKGROUND

[0002] A thermo-mechanical method for curling hair comprises, in a known manner, the following steps:

[0003] - providing a hair styling appliance comprising a mandrel, said mandrel being heatable and having a strand winding radius greater than 10 mm, for example approximately 12.5 mm,

[0004] - winding a strand of hair around the mandrel,

[0005] - heating the strand of hair wound around the mandrel at a heating temperature of between 170 and 230°C, for example approximately 200°C,

[0006] - applying a high winding stress to the strand of hair wound around the mandrel.

[0007] The use of a mandrel having a high winding radius allows aesthetically pleasing curls to be obtained.

[0008] However, the application of a high winding stress, in particular a winding stress of more than 20 MPa, for example approximately 30 MPa, on the strand of hair leads to a deterioration of the internal structure of the hair, in particular of the cuticular fibers of the hair.

[0009] Furthermore, heating the hair wound around the mandrel at a heating temperature of between 170 and 230°C also causes damage to the hair, in particular when this temperature is associated with the winding stress mentioned above.

[0010] Finally, it turns out that the persistence of the curls obtained with this curling method, i.e. their durability over time, is insufficient. SUMMARY

[0011] The present invention aims to remedy all or part of these drawbacks.

[0012] The basic technical problem of the present invention is in particular to provide a method for curling hair that allows curls to be obtained with enhanced persistence, while limiting the risk of deterioration of the hair.

[0013] To this end, the present invention relates to a method for curling hair, advantageously a thermo-mechanical method for curling hair, comprising the following steps:

[0014] - providing a hair styling appliance comprising a mandrel, said mandrel being heatable and having a strand winding radius of between 2.5 and 7.5 mm, for example between 4 and 6 mm, and advantageously approximately 5 mm,

[0015] - winding a strand of hair around the mandrel, and

[0016] - applying a winding stress on the strand wound around the mandrel of less than or equal to 0.25 MPa.

[0017] This expression of "heatable mandrel" refers to various types of mandrels well known to the person skilled in the art. It thus particularly includes mandrels that are directly heated, i.e. the mandrel itself can provide heat, for example by including a heating element therein, for example such as a resistor; i.e. the heat is inside the mandrel. This expression also encompasses mandrels that are indirectly heated, i.e. the mandrel will release the heat it has accumulated, for example after being placed in a hot environment, or by receiving heat from the outside, for example by receiving a hot air flow.

[0018] Mandrel refers to any shape, preferably cylindrical, used as support to wind around the element, in this case the hair. For example, in an illustrative and non-limiting manner, the mandrel can have a cross-section that is circular, elliptical, polylobed (clover shape), etc.

[0019] It was previously accepted in the prior art that, in order to obtain curls with high persistence, it was necessary to apply a high winding stress on the strand wound around the mandrel.

[0020] However, surprisingly, the Applicant found that winding the strand around a mandrel with a smaller winding radius, and therefore with a smaller diameter, with a lower winding stress, allows obtaining curls with a higher persistence than those obtained with the curling methods of the prior art.

[0021] The curling method according to the application thus allows obtaining curls that last a long time, while significantly reducing the internal deterioration of the hair, since the hair is subjected to very low winding stresses during the winding step.

[0022] The curling method can also have one or more of the following features, alone or in combination.

[0023] According to one embodiment of the application, the mandrel has a mandrel diameter of between 5 and 15 mm, for example between 8 and 12 mm, and advantageously of about 10 mm.

[0024] According to one embodiment of the application, the winding step and the applying step are carried out simultaneously.

[0025] According to one embodiment of the application, the method of curling hair further comprises heating the hair strand wound around the mandrel at a heating temperature between 110 and 150°C, preferably below 144°C, which corresponds to the glass transition temperature of the hair. The heating temperature can for example be between 120 and 140°C, and advantageously be about 130°C. It was previously accepted in the prior art that to obtain curls with high persistence, the hair strand wound around the mandrel had to be heated at a high temperature, in particular at a temperature of about 200°C. Surprisingly, the Applicant has found that heating the hair strand wound around the mandrel at a temperature between 110 and 150°C is sufficient to obtain curls with high persistence. This arrangement thus allows to further limit the risk of deterioration of the hair wound around the mandrel.

[0026] According to one embodiment of the application, the winding step comprises manually or automatically winding the hair strand around the mandrel.

[0027] According to one embodiment of the application, the hair styling appliance comprises a gripping body configured to allow a user to be able to manipulate the hair styling appliance.

[0028] According to one embodiment of the application, the mandrel is configured to be rotationally coupled to the gripping body, i.e. to be rotationally integral with the gripping body, and the winding step comprises driving the gripping body in rotation about a rotation axis substantially parallel to the extension axis of the mandrel, so as to manually wind the hair strand around the mandrel. Advantageously, the mandrel is fixedly mounted on the gripping body.

[0029] According to one embodiment of the application, the hair styling appliance comprises a drive motor configured to drive the mandrel in rotation about a rotation axis substantially parallel to the extension axis of the mandrel, and the winding step comprises driving the mandrel in rotation, so as to automatically wind the hair strand around the mandrel.

[0030] According to one embodiment of the application, the hair styling appliance comprises a winding device mounted so as to be able to rotate about the mandrel, and a drive motor configured to drive the winding device in rotation about the mandrel, and the winding step comprises driving the winding device in rotation, so as to automatically wind the hair strand around the mandrel.

[0031] According to one embodiment of the application, the hair styling appliance comprises a housing fixed to the gripping body and housing the winding device and the mandrel.

[0032] According to one embodiment of the application, the housing comprises a face opening provided at a free end of the housing located opposite the gripping body, and a first side opening and a second side opening each extending from the face opening in the direction of the gripping body.

[0033] According to one embodiment of the application, the shell and the winder at least partially delimit an outer chamber configured to receive the strand of hair before the strand of hair is shaped, and the mandrel and the winder at least partially delimit an inner chamber configured to receive the strand of hair after the strand of hair is shaped.

[0034] According to one embodiment of the application, the hair styling appliance comprises a hair fixing device arranged at the distal end of the mandrel. The hair fixing device may, for example, comprise a plurality of pins protruding from the distal end of the mandrel.

[0035] According to one embodiment of the application, the hair styling appliance comprises a coupling member, such as a clutch, movable between a coupled position, in which the coupling member is mechanically coupled to the mandrel or to the winder, and a decoupled position, in which the coupling member is mechanically decoupled from the mandrel or from the winder, the coupling member being configured to be in the coupled position when the winding stress applied on the strand of hair wound around the mandrel is less than 0.25 MPa and to be displaced in the decoupled position when the winding stress applied on the strand of hair wound around the mandrel reaches or exceeds 0.25 MPa.

[0036] According to one embodiment of the application, the coupling member is configured to be in the coupled position as long as a winding torque applied on the mandrel or on the winder, for example by the user via the gripping body or by the drive motor, remains less than a predetermined value during the winding step, and to be displaced in the decoupled position when the winding torque applied on the mandrel or on the winder becomes greater than or equal to the predetermined value during the winding step.

[0037] According to one embodiment of the application, the coupling member is mechanically interposed between the gripping body and the mandrel, or between the mandrel and the output shaft of the drive motor, or between the winder and the output shaft of the drive motor.

[0038] According to one embodiment of the application, the hair styling appliance comprises a stress sensor configured to determine the winding stress applied on the strand of hair wound around the mandrel, and a control unit configured to displace the coupling member in the decoupled position when the winding stress determined by the stress sensor reaches or exceeds 0.25 MPa.

[0039] According to one embodiment of the application, the hair styling appliance comprises a retaining member mounted so as to be movable between a first operating position, in which the retaining member is distanced from the mandrel so as to allow positioning of the strand of hair between the mandrel and the retaining member, and a second operating position, in which the retaining member is configured to bear against the mandrel so as to allow clamping of the strand of hair between the mandrel and the retaining member.

[0040] According to one embodiment of the application, the hair styling appliance comprises a heating element, said heating element being integrated into the mandrel and configured to heat the mandrel. BRIEF DESCRIPTION OF DRAWINGS

[0041] In any case, the present application will be clearly understood with the help of the following description, made with reference to the drawings, which show, by way of non-limiting example, one embodiment of such a hair styling appliance.

[0042] Figure 1 is a flowchart showing the steps of a curling method according to the present application.

[0043] Figure 2 is a perspective view of a hair styling appliance that can be used under the framework of a curling method according to the present application.

[0044] Figure 3 is a cutaway perspective view of another hair styling appliance that can be used under the framework of a curling method according to the present application.

[0045] Figure 4 is a cross-sectional schematic view of a hair strand as it starts to be wound around a mandrel according to a curling method of the present application.

[0046] Figure 5 is a cross-sectional schematic view of a hair strand as it ends to be wound around a mandrel according to a curling method of the present application. DETAILED DESCRIPTION

[0047] The present application relates to a thermal mechanical curling method, said method notably comprising a providing step S1 comprising providing a hair styling appliance.

[0048] Figure 2 An embodiment of a hair styling appliance 1 that can be provided at the providing step S1 is shown. The hair styling appliance 1 comprises a gripping body 2, e.g. a handle or a grip, configured to allow a user to manipulate the hair styling appliance 1 during use.

[0049] The hair styling appliance 1 further comprises a mandrel 3 elongating the gripping body 2 along a longitudinal axis A. The mandrel 3 has a winding radius r for winding a hair strand X, which winding radius is between 2.5 and 7.5 mm, e.g. between 4 and 6 mm, and advantageously about 5 mm. The mandrel 3 can for example be cylindrical and have a mandrel diameter between 5 and 15 mm, e.g. between 8 and 12 mm, and advantageously about 10 mm.

[0050] According to Figure 2 The embodiment shown, the mandrel 3 is rotationally coupled to the gripping body 2, i.e. the mandrel 3 is for example fixedly mounted on the gripping body 2.

[0051] The gripping body 2 comprises an inlet 200 for a power supply cord, for example an electrical cord. In the present description, the inlet 200 advantageously constitutes the reference point involved in the expressions "proximal" and "distal": thus, the expression "proximal end" refers to the end located on the side of the inlet 200, while the expression "distal end" refers to the end opposite the inlet 200.

[0052] The hair styling appliance 1 also comprises a retaining member 4, for example a retaining block, mounted so as to be movable with respect to the gripping body 2 between a first operating position, in which the retaining member 4 is distanced from the mandrel 3, so as to allow the positioning of a strand X between the mandrel 3 and the retaining member 4, and a second operating position, in which the retaining member 4 is configured so as to abut against the mandrel 3, so as to allow the clamping of a strand between the mandrel 3 and the retaining member 4.

[0053] The retaining member 4 has a substantially arcuate shape which is adapted to the shape of the mandrel 3, i.e. which is complementary to the shape of the mandrel 3. The proximal end 5 of the retaining member 4 is fixed to an operating finger 6 which is hingedly mounted to the distal end 7 of the gripping body 2. Pressing on the rear portion 8 of the operating finger 6 allows the displacement of the retaining member 4 to the first operating position, so as to allow the introduction of a strand between the mandrel 3 and the retaining member 4. A spring 9, for example arranged along an axis substantially perpendicular to the longitudinal axis A, between the distal end 7 of the gripping body 2 and the operating finger 6, allows the displacement of the retaining member 4 to the second operating position when the pressing on the rear portion 8 of the operating finger 6 is stopped, as shown in Figure 2 which allows the clamping of a strand (not shown) located between the mandrel 3 and the retaining member 4.

[0054] According to the embodiment shown in Figure 2 the distal end 11 of the retaining member 4 is substantially located opposite the distal end portion 12 of the mandrel 3.

[0055] The hair styling appliance 1 also comprises a heating element 13, for example an electrical resistor, integrated into the mandrel 3 and configured so as to heat the mandrel 3, and a control unit 14 configured so as to regulate the heating temperature of the heating element 13. According to an alternative embodiment of the application, the hair styling appliance 1 can be devoid of a heating element and configured so as to release the heat which it has accumulated, for example after being placed in a hot environment, or to receive heat from the outside, for example from a hot air flow.

[0056] The curling method according to the application also comprises a winding step S2, said step comprising winding the strand around the mandrel 3.

[0057] According to an embodiment of the curling method according to the application, this winding step S2 in particular comprises:

[0058] - a first displacement step, comprising the displacement of the retaining member 4 to the first operating position,

[0059] - a positioning step comprising positioning the hair strand between the holding member 4 and the mandrel 3,

[0060] - a second displacement step comprising displacing the holding member 4 to the second operating position,

[0061] - a step for driving rotation comprising driving the gripping body 2 in rotation about a rotation axis which is substantially parallel to the longitudinal axis A, for example coinciding with the longitudinal axis A, so as to manually wind the hair strand around the mandrel 3.

[0062] According to an alternative embodiment of the curling method, the hair styling appliance 1 can comprise a drive motor configured to drive the mandrel 3 in rotation about a rotation axis which is substantially parallel to the longitudinal axis A, for example coinciding with the longitudinal axis A, and the step for driving rotation then comprises driving the mandrel 3 in rotation about the rotation axis so as to automatically wind the hair strand around the mandrel 3. The mandrel 3 would then be pivotally coupled about the longitudinal axis A with respect to the gripping body 2.

[0063] According to another embodiment of the curling method, the hair styling appliance 1 provided in the providing step S1 can comprise a winder instead of the holding member 4, the winder being hollow and mounted so as to be able to rotate about the mandrel 3, and further comprising a drive motor configured to drive the winder in rotation about a rotation axis which is substantially parallel to the longitudinal axis A and for example coinciding with the longitudinal axis A, and the step for driving rotation would comprise driving the winder in rotation so as to automatically wind the hair strand around the mandrel 3.

[0064] Figure 3 A hair styling appliance 1 according to this embodiment of the curling method and which can be provided in the providing step S1 is shown.

[0065] Figure 3 The hair styling appliance 1 shown in the middle comprises a hollow housing 11 fixed to the gripping body 2. The housing 11 has a free end 12 designed to be substantially perpendicular to the user's head, more particularly to the user's scalp, when the curling operation is performed. The housing 11 houses the mandrel 3 and forms, inside it, a winding chamber 13 designed to receive the hair strand in an outer chamber 131 before the hair strand is shaped and then in an inner chamber 132 after the hair strand is shaped.

[0066] The casing 11 comprises a face opening 14 formed at the free end 12 of the casing 11, as well as a first side opening 15 and a second side opening 16, each extending from the face opening 14 in the direction of the gripping body 2. The first side opening 15 is designed to receive a strand of hair, in particular when the free end 12 is placed substantially perpendicular to the head of the user. The second side opening 16 advantageously takes the form of an inverted T-shaped notch extending from the free end 12. The particular shape of the second side opening 16 allows the strand of hair to be held at the bottom of the second side opening 16 when the strand of hair is placed in the "small rod" of the T, and optimizes the guidance of the strand of hair during the winding thereof.

[0067] Figure 3 The illustrated hair styling appliance 1 also comprises a winder 17 mounted so as to be able to rotate relative to the mandrel 3 and configured to wind a strand of hair around the mandrel 3 when the winder 17 is rotated in a predetermined direction. The winder 17 is disposed in the casing 11.

[0068] The winder 17 is hollow and has a rotationally symmetrical shape. The winder 17 is positioned coaxially around the mandrel 3. The winder 17 has a first longitudinal end 171 joined to a toothed wheel 18. This toothed wheel 18 meshes with a worm 19 driven in rotation by a drive motor 21, which allows the drive winder 17 to be rotated. The direction of rotation of the drive motor 21 is advantageously reversible, which allows the direction of rotation of the winder 17 to be reversed. The drive motor 21, the toothed wheel 18 and the worm 19 constitute an advantageous design mode of the means for driving the winder 17 in rotation, but other variants can also be envisaged without departing from the scope of the application.

[0069] The winder 17 preferably has a conical shape extending in expansion towards the direction of the distal end of the mandrel 3. However, the winder 17 can have a cylindrical rather than conical rotation surface.

[0070] The winder 17 comprises a notch 172 or cut-out extending on its rotation surface and opening on a free edge 173 at a second longitudinal end 174 of said winder 17. At the two ends of the notch 172, two hooks 175 are arranged opposite each other on the prolongation of the free edge 173.

[0071] Figure 3The hair styling appliance 1 shown also comprises a hair fixing device 22 arranged at the distal end of the mandrel 3. This hair fixing device 22 comprises a plurality of pins 221 protruding from the distal end of the mandrel 3. This hair fixing device 22 allows guiding the hair strand during the winding so as to prevent the hair strand from turning around the distal end of the mandrel 3. Moreover, this hair fixing device 22 allows the hair strand to be unwound after being curled without damaging it. When the drive winder 17 is rotated, it takes away the hair strand guided on one of the pins 221 of the hair fixing device 22, forcing it to wind around the mandrel 3. Thus, the direction of the curl produced depends on the direction of rotation of the winder 17. However, a single winding direction can be provided without departing from the scope of the application.

[0072] Thus, according to Figure 3 The embodiment shown, the hair styling appliance 1 is an automatic hair styling appliance which allows automatically winding a hair strand around the mandrel 3. In this case, unlike Figure 2 The embodiment shown, the hair styling appliance 1 is an automatic hair styling appliance which allows automatically winding a hair strand around the mandrel 3. In this case, unlike

[0073] The curling method according to the application also comprises a heating step S3 comprising heating the hair strand wound around the mandrel 3 at a heating temperature between 110 and 150°C, for example between 120 and 140°C, advantageously of the order of 130°C.

[0074] The curling method according to the application also comprises an application step S4 comprising applying a winding stress on the hair strand wound around the mandrel 3 which is less than or equal to 0.25 MPa.

[0075] According to an embodiment of the curling method, the hair styling appliance 1 provided in the provision step S1 also comprises a coupling member, for example mechanically interposed between the gripping body 2 and the mandrel 3 or between the mandrel 3 and the output shaft of the aforementioned drive motor, said coupling member being movable between a coupled position, in which the coupling member is mechanically coupled to the mandrel 3, and a decoupled position, in which the coupling member is mechanically decoupled from the mandrel 3, the coupling member being configured to be in the coupled position when the winding stress applied on the hair strand wound around the mandrel 3 is less than 0.25 MPa and to be displaced to the decoupled position when the winding stress applied on the hair strand wound around the mandrel 3 reaches or exceeds 0.25 MPa.

[0076] In Figure 3 In the embodiment shown, the coupling member is mechanically interposed between the drive motor and the winder.

[0077] Such a configuration of the coupling member allows not to transmit a rotational torque onto the mandrel 3 when the winding stress applied on the hair strand wound around the mandrel 3 reaches or exceeds 0.25 MPa, thereby limiting the deterioration of the hair during the winding phase.

[0078] The displacement of the coupling member between the coupling position and the decoupling position can for example be mechanically controlled. To this end, the coupling member can be configured to be in the coupling position as long as the winding torque applied on the mandrel 3 during the winding step, for example applied on the mandrel 3 by the user by gripping the main body 2 or, if the hair styling appliance is motorized, by a drive motor, remains below a predetermined value, and to be displaced in the decoupling position when the winding torque applied on the mandrel 3 during the winding step reaches or exceeds the predetermined value.

[0079] The displacement of the coupling member between the coupling position and the decoupling position can also be electrically or electronically controlled. To this end, the hair styling appliance 1 can comprise a stress sensor configured to determine the winding stress applied on the hair strand wound around the mandrel 3, and the control unit 14 can be configured to control the displacement of the coupling member in the decoupling position when the winding stress determined by the stress sensor reaches or exceeds 0.25 MPa.

[0080] To demonstrate the advantages of the hair curling method according to the application, various hair curling methods were applied on test hair strands formed from real human hair. The various hair curling methods differed in particular in the hair curling parameters used, such as the heating temperature applied in the heating step, the mandrel diameter of the mandrel used in the winding step and the winding stress applied in the application step.

[0081] The results obtained from these various hair curling methods are partly recorded in the two tables reproduced below.

[0082] The first table reproduced below shows the curl index, also called Curl Index, as a function of the heating temperature and the mandrel diameter. The results mentioned in the first table were obtained by applying a winding stress of 0.25 MPa in the application step.

[0083] The curl index corresponds to the ratio of the length of the hair strand in a rest state after the hair curling to the length of said hair strand in an extended state before the hair curling. In the extended state, the hair strand is manually extended without elongation.

[0084] Thus, the lower the curl index value, the more the hair strand is curled. An analysis of the evolution of the curl index over time enables to demonstrate the durability of the hair curling, i.e. its ability to last over time.

[0085] The Applicant observed that, as can be seen in Table 1 reproduced below, which illustrates the evolution of the curl index as a function of the hang time of the tresses, most of the loosening of the curl occurs in the first three hours after curling.

[0086] [Table 1]

[0087] Time (hours) Tortuosity Index 0 0.42 0.5 0.66 1 0.72 1.5 0.73 2 0.74 2.5 0.75 3 0.75 5 0.76 10 0.77 15 0.77 20 0.77 22 0.77

[0088] Table 2 is reproduced below, which shows the curl index and the state of the internal structure of the hair as a function of the heating temperature, the mandrel diameter and the winding stress.

[0089] [Table 2]

[0090]

[0091]

[0092] Each "curl index" value mentioned in Table 2 corresponds to the average of a plurality of "curl index" values obtained by applying the same curling method to at least five identical test tresses. The measurements were made 3 hours after the curling method according to the application was performed.

[0093] As can be seen from Table 2 reproduced above, contrary to existing prejudices, a high heating temperature, for example of the order of 200°C, has a very small effect on the curl index, and therefore on the persistence of the curl.

[0094] As can also be seen from Table 2 reproduced above, for a winding stress of 0.25 MPa, the smaller the mandrel diameter, the lower the curl index.

[0095] As can be seen from Table 2, the application of a winding stress of 0.25 MPa in the application step does not cause any deterioration of the internal structure of the hair.

[0096] As can also be seen from Table 2, the combination of a winding stress of 0.25 MPa with a small mandrel diameter, for example of 10 mm, allows a significantly lower curl index to be obtained than the combination of a high winding stress, for example greater than 20 MPa, with a large mandrel diameter, in particular of the order of 25 mm, without deteriorating the internal structure of the hair being treated.

[0097] Of course, the application is not limited to the embodiments described and illustrated, which are provided by way of example only. There can be some modifications, in particular in the constitution of the various elements or by substitution with equivalent techniques, without departing from the scope of protection of the application.

Claims

1. A method for curling hair, comprising the following steps: - Provides a hair styling tool (1), said hair styling tool including a mandrel (3) capable of being heated and having a winding radius (r) of hair strands (X) between 2.5 and 7.5 mm, - Wrap the hair bundle (X) around the mandrel (3), and - Apply a winding stress of less than or equal to 0.25 MPa to the hair bundle (X) wound around the mandrel (3).

2. The hair curling method according to claim 1, further comprising heating the hair bundle (X) wrapped around the mandrel (3) at a heating temperature between 110 and 150°C.

3. The hair curling method according to claim 1 or 2, wherein, The winding step includes manually or automatically winding the hair bundle (X) around the mandrel (3).

4. The hair curling method according to any one of claims 1 to 3, wherein, The hair styling appliance (1) includes a gripping body (2) configured to allow a user to manipulate the hair styling appliance (1).

5. The hair curling method according to claim 4, wherein, The mandrel (3) is configured to be rotatably coupled to the gripping body (2), and the winding step includes driving the gripping body (2) to rotate about a rotation axis that is substantially parallel to the extension axis of the mandrel (3) in order to manually wind the hair bundle (X) around the mandrel (3).

6. The hair curling method according to claim 4, wherein, The hair styling appliance (1) includes a drive motor configured to drive the mandrel (3) to rotate about a rotation axis substantially parallel to an extension axis of the mandrel (3), and the winding step includes driving the mandrel to rotate so as to automatically wind the hair bundle (X) around the mandrel (3).

7. The hair curling method according to claim 4, wherein, The hair styling appliance (1) includes a winder mounted to rotate around the mandrel (3) and a drive motor configured to drive the winder (22) to rotate around the mandrel (3), and the winding step includes driving the winder to rotate so as to automatically wind the hair bundle (X) around the mandrel (3).

8. The hair curling method according to any one of claims 5 to 7, wherein, The hair styling appliance (1) includes a connecting member movable between a connected position and a disconnected position, wherein in the connected position the connecting member is mechanically connected to the mandrel (3) or the winder, and in the disconnected position the connecting member is mechanically disconnected from the mandrel (3) or the winder. The connecting member is configured to be in the connected position when the winding stress applied to the hair bundle (X) wound around the mandrel (3) is less than 0.25 MPa, and to be in the disconnected position when the winding stress applied to the hair bundle (X) wound around the mandrel (3) reaches or exceeds 0.25 MPa.

9. The hair curling method according to claim 8, wherein, The connecting member is configured such that it is in the connected position as long as the winding torque applied to the mandrel (3) or the winder during the winding step remains below a predetermined value, and is displaced to the separated position when the winding torque applied to the mandrel (3) or the winder during the winding step becomes greater than or equal to the predetermined value.

10. The hair curling method according to claim 8, wherein, The hair styling appliance (1) includes a stress sensor and a control unit (14), the stress sensor being configured to determine the winding stress applied to the hair bundle (X) wound around the mandrel (3), and the control unit being configured to displace the connecting member to the separation position when the winding stress determined by the stress sensor reaches or exceeds 0.25 MPa.

11. The hair curling method according to any one of claims 1 to 10, wherein, The hair styling appliance (1) includes a retaining member (4) mounted to be movable between a first operating position and a second operating position. In the first operating position, the retaining member (4) is away from the spindle (3) to allow a hair bundle (X) to be positioned between the spindle (3) and the retaining member (4). In the second operating position, the retaining member (4) is configured to abut against the spindle (3) to allow the hair bundle (X) to be clamped between the spindle (3) and the retaining member (4).

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