Cutting element for a hair cutting device, manufacturing method and hair cutting device

Abstract

The present disclosure relates to tactile wear indicators for cutting elements. A cutting element (106) for a hair cutting device (100) is described. The cutting element (106) comprises a tactile wear indicator (140) defining a skin contact surface of the cutting element (106). The tactile wear indicator (140) comprises an abradable outer layer (148) of a coating material having a dry lubricant additive (150).

Description

Technical Field

[0001] The present invention relates to a cutting element for a hair cutting device, and more particularly to a tactile device for informing a user of the wear of the cutting element (especially the blade at its cutting edge). Background Technology

[0002] Hair cutting devices such as manual razors or electric shavers are widely used for cutting body hair and typically include a handle and a cutting element on which one or more blades are mounted. Some cutting elements, such as those used in electric shavers, have a reciprocating cutter comprising a fixed outer cutting member and a movable inner cutting member that reciprocates relative to the outer cutting member to perform the cutting operation. In some arrangements, the fixed outer cutting member may be provided with a plurality of blades (or teeth) arranged in a row, while the inner cutting member may also be provided with a plurality of blades (teeth) arranged in a row for engaging with the cutting blades of the outer cutting member. In use, the fixed outer cutting member may come into direct contact with the user's skin.

[0003] With use, the blades of a cutting element dull, leading to reduced cutting performance and increased hair pulling. However, the degree of wear on the blade is not easily discernible through visual inspection. Therefore, it is known to equip cutting elements with visual wear indicators, which provide the user with an indirect indication of the blade's wear level. Visual wear indicators typically comprise a layer of abrasive material fixed to the cutting element near the blade and configured to allow for discernible wear during sliding contact with the user's skin throughout the cutting element's service life. Thus, the degree of wear on the layer provides a visual indication of blade wear.

[0004] However, the problem with known wear indicators is that their effectiveness depends on what the user can see. If the user does not see a visual wear indicator, wear on the blade is not easily detected during the cutting element's stroke until the dulled blade jams and pulls on hair, which can be painful for the user. Therefore, there is a need for alternative or supplementary devices to indicate the wear of the cutting element to the user. Summary of the Invention

[0005] According to one aspect, a cutting element for a hair cutting device is provided, wherein the cutting element includes: a cutting edge, a skin-facing region, and a tactile abrasion indicator in the skin-facing region; wherein the tactile abrasion indicator includes an abrasive outer layer defining a skin-contact surface of the cutting element, the abrasive outer layer including a coating material having a dry lubricant additive.

[0006] The abrasive outer layer can define the skin contact surface of the cutting element at any point during the working life of the abrasion indicator. For example, the abrasive outer layer can be one of multiple abrasive layers of coated material that will form the skin contact outer surface of the cutting element at the corresponding point during the working life of the tactile abrasion indicator.

[0007] By providing a skin-contact surface defined by an outer layer of coating material with a dry lubricant additive, friction between the cutting element and the user's skin can be reduced during the cutting stroke of the cutting element along the skin. The dry lubricant additive is particularly effective at reducing friction during both dry and wet shaving, thereby improving the versatility of the cutting element for different shaving types. This is especially true compared to the hypothetical arrangement that provides a water-soluble lubricant.

[0008] The outer layer of the coating material is abrasive because it is constructed to wear down over time (e.g., when it slides against the user's skin) through abrasions or other means. In this way, the skin-contact surface may lose a certain amount of dry lubricant additive, thus reducing lubrication and the sliding performance of the cutting element as the abrasive outer layer wears down. The user may feel the loss of dry lubricant additive due to increased friction with the skin during the cutting stroke (as the layer wears down). In other words, the wear of the outer layer of the coating material causes the coefficient of friction of the skin-contact surface (i.e., the ratio of the force required to move the skin-contact surface along the skin to the normal force holding them together) to increase with the wear of the abrasive outer layer. This increase in friction can be used to provide the user with a tactile indication that the cutting element and the blade at the cutting edge are worn.

[0009] Tactile wear indicators can have one of many different configurations. In one embodiment, the abrasive outer layer of the coating material can be coated with a first material having a higher coefficient of friction than the coating material forming the abrasive outer layer, such that friction along the skin contact surface will increase as the abrasive outer layer of the coating material layer wears more at the interface between the coating material and the first material. In this respect, the outward-facing surface of the first material covered by the abrasive outer layer may become increasingly exposed, and a larger and larger portion of the skin contact surface may form as the abrasive outer layer wears more at the interface between the coating material and the first material.

[0010] The first material may be a material that does not contain dry lubricant additives, or it may be a material that contains a smaller amount (by weight percentage of the material) of dry lubricant additives than the amount of coating material forming the abrasive outer layer. The first material may be the outward-facing surface of the cutting element in its skin-facing area. However, in some embodiments, the tactile abrasion indicator itself may have a multi-layered structure, and the first material may be a coating material forming a first layer of the abrasion indicator, which is covered by an abrasive outer layer of coating material.

[0011] The coating material (forming the wearable outer layer) may include 1 to 20%, for example 1 to 10%, for example 5%, by weight of dry lubricant additive.

[0012] The coating material may include multiple dry lubricant particles dispersed within the adhesive.

[0013] At least some dry lubricant particles may protrude from the adhesive, such that they form at least a portion of the skin-contact surface of the cutting element. The dry lubricant additive may be exposed on the outer surface of the cutting element.

[0014] Dry lubricant particles can be in the form of spherical beads.

[0015] At least some dry lubricant particles can have a span greater than the thickness of the adhesive in the wearable outer layer. In the case where the dry lubricant particles are in the form of spherical beads, the corresponding diameter of the dry lubricant particles can be greater than the thickness of the adhesive in the wearable outer layer.

[0016] Dry lubricant additives can be formed from glass. For example, dry lubricant particles can be glass particles.

[0017] The coating material may include adhesives in the form of inks or paints.

[0018] The cutting element may also include a visual abrasion indicator. The visual abrasion indicator may be located in a skin-facing area, for example, on the outward-facing surface of the cutting element within the skin-facing area. The visual abrasion indicator may be covered by an abrasive outer layer. The visual abrasion indicator may have an appearance that contrasts with the abrasive outer layer. The visual abrasion indicator may be exposed when the abrasive outer layer abrades (e.g., is worn).

[0019] A visual abrasion indicator can take the form of a first coating material layer fixed to a cutting element. A visual abrasion indicator can also be part of a tactile abrasion indicator. For example, the first coating material can be a material with a higher coefficient of friction than the first coating material forming the abrasive outer layer.

[0020] The first layer may have a first color that is different from the color of the abrasive outer layer. Additionally or alternatively, the first layer may have markings or patterns on the surface covered by the abrasive outer layer.

[0021] The wearable outer layer may have a wear rate related to the wear rate of the blade of the cutting element.

[0022] According to another aspect, a hair cutting device is provided, which includes any of the cutting elements described above.

[0023] According to another aspect, a method for manufacturing a cutting element having a tactile abrasion indicator is provided. The method may include: providing a cutting element comprising a cutting edge and a skin-facing region; and forming a tactile abrasion indicator by providing an abrasive outer layer in the skin-facing region. The abrasive outer layer defines a skin-contact surface (of the cutting element) and includes a coating material having a dry lubricant additive.

[0024] The method may also include setting a cutting element having any one or more of the features described above. Attached Figure Description

[0025] Exemplary embodiments will now be described by way of example only with reference to the following figures, in which: Figure 1 This is a front view of a hair-cutting device including an electric shaver; Figure 2 yes Figure 1 A front view of the cutting element of a hair cutting device; Figures 3a to 3c The diagram schematically illustrates different stages of wear. Figure 2 An embodiment of a tactile wear indicator for a cutting element; Figure 4 This is a flowchart illustrating a method for manufacturing a cut element with a tactile wear indicator; Figure 5 This is a flowchart illustrating a method for manufacturing the tactile wear indicator of Figure 3. Detailed Implementation

[0026] Figure 1 The image shows a hair-cutting device in the form of an electric shaver 100.

[0027] The electric shaver 100 includes an elongated body 102 having a cutting head 104 and a handle portion 108, with a cutting element 106 removably attached to the cutting head 104, and the handle portion 108 extending generally away from the cutting head 104. The body 102 is generally formed of a housing that forms the outer surface of the electric shaver body.

[0028] The handle portion 108 is an elongated, grippable section that allows the user to hold the electric shaver 100 during use. The handle portion 108 is partially covered with a rubberized or textured surface to improve grip, especially when the handle portion 108 is wet. A pop-out button 110 is located on the front of the handle portion 108, which is adapted to activate an actuator or other mechanism to separate the cutting element 106 from the cutting head 104. A power switch, actuated by a power button 112, is also located on the front of the handle portion 108, used to turn the electric shaver 100 on / off.

[0029] As will be described in further detail below, the cutting element 106 includes a first pair of fixed and reciprocating blades (each of which may include multiple blade teeth) and a second pair of fixed and reciprocating blades. The first pair of blades forms a first cutting edge 114, and the second pair of blades forms a second cutting edge 116 on the laterally opposite sides of the cutting element 106. The cutting line 118 of the electric shaver 100 is perpendicular to the first cutting edge 114 and the second cutting edge 116. The cutting line 118 defines the direction in which hairs should be located at a given cutting edge 114, 116, close to the blades, to ensure that the electric shaver 100 effectively cuts those hairs. That is, the electric shaver 100 cuts hair most effectively when moving along the direction of the cutting line 118.

[0030] In this example, the region 120 of the cutting element 106 near the first cutting edge 114 and the second cutting edge 116 in the direction along the cutting line 118 faces the skin during use. Within the skin-facing region 120, there is an external skin contact surface 122 that is typically pressed against the user's skin during use for a tight shave. The skin contact surface 122 slides along the user's skin in the direction along the cutting line 118, such that one of the cutting edges 114 and 116 moves forward along the cutting line 118 along the user's skin during the stroke of the cutting element 106 to cut any hair it encounters.

[0031] Figure 2 It shows Figure 1 Front view of the skin-facing area 120 of the cutting element 106.

[0032] The cutting element 106 includes a fixed outer cutting member 124 located above a movable inner cutting member (not shown), the movable inner cutting member being movable relative to the fixed cutting member 124 and along the cutter axis 126 in a reciprocating manner. The movable cutting member is arranged such that it is disposed within the body 102 of the electric shaver 100 (e.g., Figure 1The motor in the handle portion 108 (shown) is driven. The motor can be powered by a rechargeable battery contained within the housing of the electric shaver 100. The motor can be selectively turned on and off via a power switch using the power button 112.

[0033] The fixed cutting member 124 has opposing first sides 128 and second sides 130, which are spaced apart in a direction parallel to the cutter axis 126 and are generally parallel to each other. The fixed cutting member 124 also has opposing third sides 132 and fourth sides 134, spaced apart in a direction perpendicular to the cutter axis 126. A first cutting edge 114 and a second cutting edge 116 are located on the opposing third sides 132 and fourth sides 134 of the fixed cutting member 124, respectively. The fixed cutting member 124 includes a first set of main blade teeth 136 and a second set of main blade teeth 138 forming the first cutting edge 114 and the second cutting edge 116, respectively. The main cutting teeth 136, 138 are spaced apart along the cutting edges 114, 116 in a direction parallel to the cutter axis 126 to define a hair entry opening between them. The movable inner cutting member includes a first set of secondary blade teeth and a second set of secondary blade teeth on reciprocating blades forming the cutting edges 114, 116. During use, hair entering the opening between the main cutting teeth 136 and 138 is cut with a scissor-like action, as the main teeth of the fixed cutting member 124 and the secondary teeth of the movable cutting member pass each other.

[0034] As described above, over time, the blades (blade teeth) of both the movable and fixed cutting components become dull, leading to reduced cutting performance and increased hair pulling. Therefore, to provide the user with an indication of the degree of wear on the blade teeth, a tactile wear indicator 140 is provided on the skin-facing area 120 of the cutting element 106. The tactile wear indicator 140 is attached to the outward-facing surface 125 of the fixed cutting component 124 in the skin-facing area 120 and forms part of the skin-contact surface 122 of the cutting element 106. Figure 2 In the example, the tactile wear indicator 140 has a rectangular shape; however, the tactile wear indicator can have any shape and size suitable for covering some or all of the skin-facing area 120 of the cutting element 106.

[0035] Although not in Figure 2As shown, the tactile wear indicator 140 includes at least one outer layer of a coating material in which a dry lubricant additive is mixed. The dry lubricant additive is a solid-phase lubricating material that can be added to a binder (such as a liquid or solid powder material) and then cured to form a solid material with a reduced coefficient of friction compared to the original binder. In other words, the dry lubricant additive is a solid substance to be added to a binder to improve the lubricity of the material. Many known types of dry lubricant additives exist, such as molybdenum disulfide, polytetrafluoroethylene (PTFE), or graphite additives, which are commonly used to form anti-friction coatings applied to mating surfaces of moving components to ensure the smooth operation of these components. Traditionally, anti-friction coatings are constructed to be wear-resistant throughout the service life of the components to which they are applied, ensuring they can continue to provide lubrication between components.

[0036] In this embodiment, the outer layer has a first side that can directly or indirectly contact (e.g., via one or more other material layers) the outward-facing surface 125 of the fixed cutting member 124, and a second side opposite that forms a skin contact surface 122 on the outside of the cutting element 106. In this way, for example, compared to a hypothetical arrangement where the outer layer does not contain dry lubricant additives, the skin contact surface 122 of the cutting element 106 can provide less friction against the cutting element 106 sliding along the user's skin during its stroke.

[0037] In contrast to conventional applications that provide dry lubricant additives in anti-wear coatings, in this invention, the dry lubricant additive is provided in a coating material layer constructed to wear, for example, due to scuffing, when in contact with the user's skin and / or hair during the cutting stroke of the cutting element 106. As the outer layer wears, the lubricating properties of the skin-contact surface 122 (and therefore the enhanced sliding properties of the cutting element 106) can be significantly reduced. In this way, the user can be provided with a tactile indication of the degree of wear on the cutting element and, correspondingly, the possible degree of wear on the blade teeth. For example, the user may be able to identify cutter element wear (and therefore the need for replacement) by feeling increased friction on the skin during the cutting stroke.

[0038] Although the electric shaver with two cutting edges has already been described above... Figure 1 and Figure 2Each cutting edge is formed by a pair of fixed blades and a reciprocating blade, but this is not necessary. The present invention (particularly the tactile wear indicator) is applicable to cutting elements having any number of blades or cutting edges. Furthermore, the wear indicator is more broadly applicable to cutting elements of any type of hair cutting device, such as the cutting elements of a manual razor, which have one or more fixed blades disposed on a fixed cutting member. Moreover, the cutting element does not need to be removably attached to the body of the cutting device, but can instead be formed as an integral part of a single body.

[0039] Figures 3a to 3c The schematic diagram shows the setting. Figure 2 An example embodiment of the tactile wear indicator 140 on the cutting element 106. Figures 3a-3c Tactile wear indicators 140 are shown for new, partially worn, and fully worn cutting elements at the expected end of their working life. Figures 3a-3c Each of the figures shows two views of the wear indicator 140: a first cross-sectional view (on the left-hand side of the figure) along a portion of line AA, which runs through the indicator 140 between the third and fourth sides of the cutting element; and a second front view (on the right-hand side of the figure) through the skin-facing surface 122 formed by the wear indicator 140.

[0040] In the example arrangement of Figure 3, the wear indicator 140 has a multi-layer structure in which four coating material layers 142, 144, 146, and 148 are arranged in a stacked configuration on the fixed cutting member 124. This multi-layer structure includes a first layer 142 fixed to and coating at least a portion of the outward-facing surface 125 of the fixed cutting member 124, a second layer 144 fixed to and coating the first layer 142, a third layer 146 fixed to and coating the second layer 144, and a fourth layer 148 fixed to and coating the third layer 146. The third layer 146 and the fourth layer 148 are the outer layers of the wear indicator 140 because they at least partially form the skin contact surface 122 of the cutting element.

[0041] The tactile wear indicator 140 can be manufactured using any suitable manufacturing equipment and methods, the choice of which may depend on the type of coating material used for layers 142, 144, 146, and 148. In this example, each coating material layer 142, 144, 146, and 148 includes an adhesive, which in this example is a print agent 152 and 154, such as solvent-based inks or paints. Therefore, any equipment and methods for depositing the print agent onto the substrate can be used for this purpose. For example, a so-called "pad printing" device can be used to deposit the print agent onto the surface, thereby bringing deformable printed pads (e.g., silicon pads) into contact with a pre-prepared print agent plate and transferring the print agent from the printing plate to the substrate surface to be printed.

[0042] The different coating material layers 142, 144, 146, 148 forming the wear indicator 140 can be made of the same coating material or different coating materials, such as printing agents with different compositions. In this respect, the coating material may include printing agents and optionally one or more filler materials, such as adhesive resins and hardener materials such as varnishes. The specific composition of the coating material may depend on the function of the layer in question.

[0043] In this example, the first layer 142 and the second layer 144 are permanent, wear-resistant coating layers configured to remain in proper position on the fixed cutting member 124 at least during the expected normal operating life of the cutting element. However, the third layer 146 and the fourth layer 148 of the coating are configured to wear away during the normal operating life of the cutting element, starting with the exposed outer fourth layer 148, followed by the third layer 146, which will gradually become more exposed as the fourth layer 148 wears away. Therefore, the composition of the coating in each layer can be adjusted and selected during manufacturing to ensure that the coating in the first layer 142 and the second layer 144 has a wear rate lower than that of the coating in the third layer 146 and the fourth layer 148. Furthermore, the coating composition can be adjusted to ensure that both the third layer 146 and the fourth layer 148 will have a wear rate related to the wear rate of the cutting element's blade, i.e., to ensure that the coating for the third layer 146 and the fourth layer 148 will be completely worn away (e.g., to the point where they are hard) when the cutting element's blade also wears away.

[0044] Without being bound by theory, the time required for a given coating layer to completely wear down (or more precisely, the number of uniformly sized cuts) will depend on the thickness of the coating (particularly the ink and filler in the layer, if present) (measured along the normal to the surface that holds the layer) and the wear rate of the coating in that layer (expressed as the volume of ink lost per cut). The wear rate of a layer of known thickness can be determined, for example, by determining the size of the cutting element required to completely wear down the layer, the number of uniformly sized cuts (in terms of the distance traveled along the skin), and based on this, calculating the volume of coating lost per cut.

[0045] like Figure 3aAs best shown, in addition to the printing agents 152, 154 (and fillers, if present) in the third layer 146 and the fourth layer 148, the third and fourth layers of the coating material also include a dry lubricant additive 150. In the example shown, the dry lubricant additive 150 is in the form of a plurality of dry lubricant particles 150 to reduce friction encountered by the skin when sliding in contact with the third layer 146 and the fourth layer 148. At least some of the dry lubricant particles 150 are exposed outside the wear indicator 140 in the fourth outer layer 148, such that they, together with the printing agent 154, define the skin contact surface 122 of the cutting element.

[0046] The dry lubricant particles 150 are at least partially encapsulated by the printing agents 152, 154 forming the third layer 146 and the fourth layer 148, such that they are retained by the printing agents 152, 154 during normal use of the cutting element, despite the cutting forces acting on the particles during normal cutting strokes. At this point, the dry lubricant particles 150 will remain adhered to the printing agents 152, 154, and thus provide lubrication benefits until most (if not all) of the printing agents 152, 154 encapsulating the particles 150 are worn away and depleted. This is in contrast to a hypothetical arrangement in which the cutting element is provided with a lubrication device comprising a permanent substrate and a soluble lubricant configured to continuously leach from the substrate during use in conjunction with water to reduce friction between the substrate and the user's skin.

[0047] Any type of dry lubricant particles 150 can be used, such as dry lubricant particles formed from plastic or PTFE. However, in this embodiment, the dry lubricant particles 150 are glass particles, whose properties are particularly effective in reducing friction, while being safe for users and environmentally friendly, especially compared to plastic or PTFE-based materials. An example of glass particles suitable for this arrangement is so-called "Coatosil" additive particles, such as "Coatosil..." DSA 10 "It can be purchased from MomentivePerformance Materials Inc."

[0048] The dry lubricant particles 150 can take any suitable shape. However, in this embodiment, they are in the form of spherical beads, each bead having a substantially circular cross-section (e.g., Figure 3a and Figure 3b (As shown). This spherical shape may be particularly advantageous because it provides a circular profile that minimizes the contact area and thus minimizes friction between the user's skin and the skin contact surface 122 upon contact.

[0049] Any suitable amount of dry lubricant particles 150 can be used to reduce friction on the third layer 146 and the fourth layer 148 to enhance the sliding performance of the cutting element. However, in some arrangements, the coating material of the third layer 146 and the fourth layer 148 comprises between 1% and 20% by weight of the dry lubricant particles, for example, between 1% and 10%, such as 5%. A range of 1% to 20% should provide sufficient lubrication to achieve a significant reduction in friction, while maintaining a sufficient amount of printhead (and optional filler) in the coating material to ensure the structural integrity of the coating material, allowing it to be effectively applied and retained on the surface. Values ​​in the range of 1% to 10%, such as 5%, may be particularly advantageous because they provide an optimal balance between lubrication and structural integrity.

[0050] The skin contact surface 122 will continuously change as the third layer 146 and the fourth layer 148 wear down. The dry lubricant particles 150 are substantially dispersed throughout the prints 152 and 154, such that as the prints 152 and 154 wear down, the dry lubricant particles 150 will be newly exposed to the outside of the wear indicator 140. The particles can be substantially uniformly distributed throughout the prints 152 and 154 in the third layer 146 and the fourth layer 148, i.e., where the third layer 146 and the fourth layer 148 have the same weight percentage of dry lubricant particles 150. In this way, as the coating material in the third layer 146 and the fourth layer 148 wears down, the skin will come into contact with a substantially constant number of particles 150 and thus experience consistent sliding performance. However, in other arrangements, the fourth layer 148 of the coating material may have a larger weight percentage of dry lubricant particles than the third layer 146, such that the degree of friction increases as the fourth layer 148 wears down and the third layer 148 wears down.

[0051] In the example of Figure 3, at least some of the dry lubricant particles 150 in the third layer 146 and the fourth layer 148 protrude from the remaining coating material (particularly the prints 152, 154) in those layers. In this way, the morphology of the skin contact surface 122 (at various wear points) can include substantially flat portions formed by the prints 152, 154 and raised portions formed by the dry lubricant particles 150. By forming raised portions on the skin contact surface 122, the protruding particles 150 can lift the user's skin from the planar portion of the cutting element (and typically the wider skin contact area), thereby reducing the contact area between the cutting element and the user's skin and further improving the sliding performance during the cutting stroke. However, this effect is limited to the raised portion of the wear indicator 140, such that a portion of the skin contact surface 122 will remain in contact with the user's skin during the cutting stroke and accordingly cause wear (e.g., abrasion) of the outer layer 148 of the coating material.

[0052] In this example, the morphology described above is achieved by ensuring that the thickness of the printing agents 152 and 154 (measured in the direction normal to the surface 125 to which the wear indicator 140 is attached) is less than the span of the corresponding particle 150. The span of the particle 150 is its width or length measured along a straight line spanning from one end of the particle to the other. As mentioned above, in the case where the dry lubricant particles 150 have a spherical profile, the span of a given particle 150 will be defined by its cross-sectional diameter. Therefore, as Figure 3a As best shown, at least one dry lubricant particle 150 in the fourth layer 148 has a first diameter 158 and a thickness of, for example, about 10 micrometers, which is greater than the thickness 160 of the printing agent 154 in the fourth layer 148.

[0053] The span of the dry lubricant particles 150 need not exceed the thickness of the printed agents 152 and 154 in the given layers 146 and 148. In the example shown in Figure 3, the coating material in each of the third layer 146 and the fourth layer 148 comprises a combination of particles 150 of different sizes. For example, as Figure 3a As shown, at least one particle 150 in the fourth layer 148 has a second diameter 162 smaller than the thickness 160 of the printout 152 in that layer 148. In other arrangements, all dry lubricant particles in a given layer will have a span smaller than the thickness of the printout in that layer. In arrangements where at least some dry lubricant particles in a layer have a diameter smaller than the thickness of the printout in that layer, the properties of the printout, such as the relative density of the printout compared to the particles, can be adjusted such that the particles are directed to the outer surface of the printout, thereby protruding from the printout in that layer. Regardless of its manufacturing method, the above-described morphology can be readily identified by examining scanning electron microscope images of the wear indicator 140 captured using conventional techniques known in the art.

[0054] In this manner, the user will benefit from the enhanced sliding performance of the wear indicator 140 until the third layer 146 and the fourth layer 148 wear away. However, as the third layer 146 wears away at the interface between the third layer 146 and the second layer 144, exposing an increasingly larger surface area of ​​the second layer 144, the level of lubrication will gradually decrease. (Reference) Figure 3cIf a user chooses to perform a shaving operation using the cutting element when the third layer 146 is mostly or completely worn, the user's skin will come into contact with the exposed second layer 144. In this embodiment, the second layer 144 is formed of a coating material having a higher coefficient of friction than the coating material forming the third layer 146, such that friction along the skin contact surface 122 will increase as the third layer 146 wears down at the interface between the second and third layers 144 to expose the second layer 144. In this example, this is achieved through the second layer 144 of a coating material having zero amount of dry lubricant additive. The increased friction on the third layer 144 will be noticeable to the user as a corresponding decrease in comfort compared to when the cutting element and wear indicator 140 are new. In this way, a noticeable tactile indication of wear on the cutting element is provided to the user regardless of whether the user has already seen signs of wear on the blade at the cutting edge.

[0055] Although the wear indicator 140 has been described above as comprising a multi-layered structure with lubricated and non-lubricated layers to provide the user with tactile feedback on the wear of the cutting element, the tactile wear indicator 140 can also provide the user with a visual indication of the degree of wear on the cutting element. In this respect, one or more layers of coating material can also serve as visual wear indicators. In the arrangement of FIG. 3, each of the first layer 142, the second layer 144, and the third layer 146 of the coating material serves as a visual wear indicator because they have a unique appearance that contrasts with the appearance of at least the fourth layer 148 and are exposed when the layer immediately above the relevant layer wears. In this way, the user can visually identify the degree of wear on the cutting element or blade based on the appearance of the skin contact surface 122, i.e., based on one or more of the first layer 142, the second layer 144, the third layer 146, and the fourth layer 148 that define the skin contact surface 122.

[0056] The appearance of the different layers 142, 144, 146, and 148 can be distinguished by their colors. For example, the printing ink used for each layer 142, 144, 146, and 148 may include different colored pigments (or weight percentages of the same colored pigment). Additionally or alternatively, one or more layers 142, 144, 146, and 148 may include unique markings or patterns on their outward-facing surfaces.

[0057] refer to Figure 3a The fourth layer 148 of the tactile wear indicator 140 covers only a portion of the outward-facing surface 156 of the third layer 146 to form a crosshair pattern that is recognizable to the user as a new cut element. The third layer 146 may be substantially homogeneous in color (e.g., ...). Figure 3b(As shown by the dashed line in the right-hand view of the wear indicator 140), this will indicate to the user that the cut element has partially (at least half in this example) passed its expected service life when exposed to the fourth layer 148 due to wear.

[0058] The first layer 142 and the second layer 144 comprise coating materials of different colors, which are combined to define a permanent pattern 164, which in Figure 3c As shown in the right-hand view. For example, the thickness of the first layer 142 and the second layer 144 varies along the longitudinal range of the wear indicator 140 to define the pattern 164 exposed when the third layer 146 and the fourth layer 148 are worn. The first layer 142 and the second layer 144 indicate to the user that the cutting element is completely worn and may need to be replaced.

[0059] It should be understood that although the multilayer structure has been described above for having four coating material layers, a multilayer wear indicator may have two or more layers. For example, wear indicator 140 may include a first permanent coating material layer fixed to the outward-facing surface 125 of the cutting element, and a second outer coating material layer including a dry lubricant additive.

[0060] Furthermore, although tactile wear indicators with multi-layered structures have been described above, this is not necessary. For example, wear indicator 140 may comprise a single abrasive layer of a coating material containing a dry lubricant additive, which covers the skin-facing surface 125 of the cutting element in the skin-facing region 120 of the cutting element. In such an arrangement, the cutting element itself, particularly the surface 125 of the fixed cutting member, may be relatively abrasive because it has a higher coefficient of friction than the abrasive outer layer. Furthermore, surface 125 may have an appearance that contrasts with the outer layer, for example, by means of markings provided on the surface.

[0061] Figure 4 This is a flowchart illustrating an example method for manufacturing a cut element with a tactile wear indicator.

[0062] The method begins at box 401, where the above combination is provided. Figure 1 and Figure 2The described type of cutting element. The cutting element includes a cutting edge and a skin-facing area, and optionally any one or more features of the cutting element described above. At box 402, the method includes providing an adhesive in the form of a printing agent. An adhesive may be provided for each layer of coating material to be attached to the cutting element, or an adhesive may be provided for two or more layers of coating material to be attached to the cutting element. At box 403, the method includes combining or mixing the adhesive with a dry lubricant additive (e.g., a lubricant of the type described above) to form a coating material to be applied to the skin-facing area of ​​the cutting element. This may include mixing the adhesive with a volume of dry lubricant particles, the volume of dry lubricant particles corresponding to 1 to 20%, for example 1 to 10%, for example 5% by weight of the final mixed coating material. At this box, the method may also include adding a desired amount of filler material, such as generally as described above with respect to Figure 3. At box 404, the coating material is disposed in the skin-facing area of ​​the cutting element to form an abrasive outer layer of the dry lubricant additive, wherein this layer defines the skin contact surface of the cutting element.

[0063] The coating material can be applied to the skin-facing area by directly attaching it to the outward-facing surface of a cutting element, such as a fixed cutting member. However, in some arrangements, the tactile abrasion indicator has a multi-layered structure, so the method involves directly attaching a first layer of coating material to the outward-facing surface of the fixed cutting member, and then attaching a coating material for an abrasive outer layer (directly or indirectly via one or more other layers) on top of the first layer. As mentioned above, the first layer can be a permanent layer of coating material, such as the first or second layer described above with respect to Figure 3.

[0064] Any suitable method can be used to fix the coating material. In cases where the adhesive for the abrasive outer layer includes a printing agent, the coating material is fixed to the fixed cutting member (or the first layer) by performing a printing method. Suitable printing methods include: inkjet printing, in which droplets of liquid-phase coating material are deposited onto the surface to be coated; and additive manufacturing techniques, in which a certain amount of coating material in the form of a liquid or solid powder is continuously deposited and solidified on top of each other, for example by heating, to establish the thickness of the coating material forming the layer. In other arrangements, chemical curing techniques, such as ultraviolet curing, can be used, thereby using ultraviolet light to initiate a photochemical reaction that cures the curable printing agent.

[0065] It should be understood that the steps or blocks in the above flowchart do not need to be executed in the described order, and in some cases may be executed in the reverse order shown. In some cases, one or more blocks or steps may be executed simultaneously.

[0066] Figure 5This is a flowchart schematically illustrating a method for manufacturing a tactile wear indicator 140 having the multi-layered structure described above with respect to FIG3.

[0067] In this embodiment, each coating layer comprises a printing agent in the form of a solvent-based ink, which is printed using a method known as "pad printing," wherein an elastically deformable pad is used to transfer the coating material from a printing plate source to the surface to be coated. The method includes the following steps: 1. At frame 501, the first layer 142 is printed by depositing the coating material of layer 142 onto the outward-facing surface 125 in the skin-facing region 120 of the cutting element 106.

[0068] 2. At frame 502, the second layer 144 is printed by depositing the coating material of the second layer 144 onto the outward-facing surface of the first layer 142.

[0069] 3. At frame 503, the third layer 146 is printed by depositing the coating material of the third layer 146 onto the outward-facing surface of the second layer 144.

[0070] 4. At frame 504, the fourth layer 148 is printed by depositing the coating material of the fourth layer 148 onto the outward-facing surface of the third layer 146.

[0071] In the manner described above, the present invention can provide a universal wear indicator that provides tactile indication to the user and, in some cases, visual indication of wear on cutting elements. While the invention has been detailed and described in the accompanying drawings and foregoing description, such description and illustration are to be considered illustrative or exemplary rather than limiting; the invention is not limited to the disclosed embodiments.

[0072] For example, while embodiments of tactile wear indicators have been described above as having a layered structure where each layer has a different coefficient of friction, this is not necessary. In some cases, such as when wear indicators are manufactured using additive manufacturing techniques, a single-layer abrasive coating material may provide a gradual increase in friction as that layer wears. For example, when increasing the thickness of the coating material forming the abrasive layer, a single-layer abrasive coating material can be manufactured by providing different amounts of dry lubricant additives in a continuous deposit of the coating material. In this way, the coefficient of friction of the skin contact surface will increase as the abrasive outer layer wears.

[0073] Furthermore, additive manufacturing processes can begin building a tactile wear indicator by depositing an elastic material onto a substrate, followed by the deposition of increasingly more abrasive material. This elastic material is intended to be permanent throughout the expected normal operating life of the cut element with the continuous deposition of the coating material. This results in a tactile wear indicator having a permanent portion of the first material containing little or no dry lubricant additives, and an abrasive outer layer of coating material forming a skin-contact surface that provides lubrication benefits.

[0074] By studying the accompanying drawings, the disclosure, and the appended claims, those skilled in the art can understand and implement other variations of the disclosed embodiments in practicing the claimed invention. In the claims, the word "comprising" does not exclude other elements or steps, and the singular form does not exclude multiple. The mere fact that certain measures are recited in mutually different dependent claims does not imply that a combination of these measures cannot be used advantageously. Any reference numerals in the claims should not be construed as limiting the scope.

Claims

1. A cutting element for a hair cutting device, wherein the cutting element comprises: Cutting edge, skin-facing area, and tactile wear indicator in the skin-facing area; The tactile abrasion indicator includes an abrasive outer layer defining a skin-contact surface of the cutting element. The abrasive outer layer includes a coating material having a plurality of dry lubricant particles dispersed within an adhesive. At least some of the dry lubricant particles have a span greater than the thickness of the adhesive in the wear-resistant outer layer.

2. The cutting element of claim 1, wherein the abrasive outer layer is coated on a first material having a higher coefficient of friction than the coating material forming the abrasive outer layer, such that friction along the skin contact surface will increase with wear of the abrasive outer layer of the coating material at the interface between the abrasive outer layer and the first material.

3. The cutting element according to claim 1, wherein the coating material comprises 1% to 20% by weight of a dry lubricant additive.

4. The cutting element of claim 1, wherein at least some of the dry lubricant particles protrude from the adhesive such that the at least some of the dry lubricant particles form at least a portion of the skin contact surface of the cutting element.

5. The cutting element according to claim 1 or 4, wherein the dry lubricant particles are in the form of spherical beads.

6. The cutting element according to claim 1 or 4, wherein the dry lubricant particles are glass particles.

7. The cutting element according to claim 1 or 4, wherein the adhesive is ink or paint.

8. The cutting element according to any one of claims 1 to 4, further comprising a visual abrasion indicator disposed in the skin-facing area and covered by the abrasive outer layer; The visual wear indicator has an appearance that contrasts with the wearable outer layer, and the visual wear indicator is exposed when the wearable outer layer wears down.

9. The cutting element of claim 8, wherein the visual wear indicator is in the form of a first layer of coating material fixed to the cutting element.

10. The cutting element according to claim 9, wherein the first layer comprises: A first color different from the color of the wearable outer layer; or Markings or patterns on the surface covered by the wearable outer layer.

11. The cutting element according to any one of claims 1 to 4, wherein the abrasive outer layer has a wear rate related to the wear rate of the blade of the cutting element.

12. A hair cutting device comprising a cutting element according to any one of the preceding claims.

13. A method for manufacturing a cutting element having a tactile wear indicator, the method comprising: A cutting element is provided, the cutting element including a cutting edge and a skin-facing area; A tactile abrasion indicator is formed by providing an abrasive outer layer in the skin-facing area, wherein the abrasive outer layer defines a skin contact surface, and the abrasive outer layer includes a plurality of dry lubricant particles dispersed within an adhesive. At least some of the dry lubricant particles have a span greater than the thickness of the adhesive in the wear-resistant outer layer.

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