EP0086536A1 - Cutting-blade assembly for reciprocating dryshaver - Google Patents

Abstract

In the case of a reciprocating bottom knife for dry shavers, the arcuate knife blades (3) of which are arranged one behind the other on at least one carrier (1, 2), the knife blades (3) are grouped in pairs, the distance between them in the apex area of the knife blades (3) the two knife blades (3) of a group (4) is smaller than the distance between a knife blade of this group and the knife blade lying next to it of an adjacent group of knife blades.

Description

The invention relates to a back and forth drivable bottom knife for dry shavers, which is intended to interact with a Siebscher film and has a number of spaced apart, arranged on at least one support, curved knife blades, at least the distances between one knife blade and the two neighboring ones Knife blades are not the same size.

Such a lower knife is known from JP-GM 49-2698. In the known lower knife, the knife lamellae are arranged at different mutual distances, which are to change either block-wise or continuously. The distances between the knife blades are mainly smaller in the middle area of the lower knife, because this area is mainly involved in shaving. As a result of the different distances between the knife blades, better cutting of the hair should be achieved, because in the area of the knife blades lying closer together, the holes in the screen shear foil are crossed more often by the knife blades and the areas with knife blades located further apart ensure that the screen shear foil comes into close contact maintained with the lower knife. It should also be mentioned that it is already known that the distance between two knife blades should not be less than a certain amount, because otherwise the degree of coverage of the holes in the screen shaving foil by the knife blades will be too large, which means that the hair enters the Holes in the screen shaving foil are hindered and the shaving performance is reduced.

The invention has set itself the task of ver a lower knife of the type mentioned in terms of the shaving performance that can be achieved with it improve. This object is achieved according to the invention in that the knife blades are grouped in pairs, at least in the apex region of the knife blades the distance between the two knife blades of a group is smaller than the distance between a knife blade of this group and the knife blade of an adjacent group lying next to it. In this way, the two knife blades of a group can interact due to their smaller distance from each other in the course of cutting a hair so that the hair in question is cut off particularly short. At the same time, it is ensured that, owing to the greater distance between the knife blades of two adjacent groups, the hair can enter the holes of the screening shear film unhindered in order to be subjected to a cutting process. Overall, therefore, a very good shaving performance is obtained with such a lower knife. The fact that the knife blades are grouped in pairs also means that the different spacing relationships between the knife blades are present in succession along the entire length of the lower knife, so that the entire lower knife, and not just an area of the same that has particularly good cutting behavior.

In a first embodiment of the invention, the knife slats grouped in pairs are flat and rigid in themselves. Such knife slats are known per se; is essential to the invention that such Messerla _m Ellen are grouped in pairs, wherein the distance between the two cutter lamellae of a group is smaller than the distances thereof from the adjacent groups of cutter lamellae. In this way it is achieved that in each of the two directions of movement of the lower knife, the first knife blade of a group lying in front cuts off a hair once, a pull being exerted on the hair in question, forming a local cutting gap, so that it is pulled out of its skin pocket somewhat becomes. Immediately after this first knife blade has passed and the cutting gap has receded the remaining stub of hair straightens up again in the hole in the shear foil, so that it is cut off again by the immediately following second knife blade of this group. As can be seen, the grouping of pairs of stiff knife lamellae, which are therefore both effective as cutting knives, with a smaller spacing means that each hair is cut twice in quick succession, which results in a shorter cut of the hair and thus one gives better shaving performance. The greater distance between the knife blades of two adjacent groups of knife blades ensures that hair can enter the holes of the screen shaving foil without hindrance.

In a second embodiment of the invention, the paired knife blades are designed to be elastically resilient in at least one of the two directions of the reciprocating drive movement for the lower knife, the front knife blade of each of the two knife blades of a group, viewed in each of the two directions of movement in its function resilient leading knife and the rear knife blade is effective as a stiff cutting knife in its function. A leading knife is understood to mean a hair pulling element which pulls the hair out of its skin pocket before it is cut off by the subsequent cutting knife, as is the case for example in AT-PS 333.151, AT-PS 360.375 or also from US-PS 3,088,205 and DE-OS 2,850,827 emerges. In the present context, the pairing of the knife blades in a simple manner means that one blade blade of each group can act as a leading knife and the other knife blade as a cutting knife in both directions of movement of the lower knife, i.e. it pulls the leading blade blade on the hair and pulls it out pulls out his skin pocket and only the subsequent knife blade actually cuts the hair. This cuts the hair shorter again and it also ensures that between two adjacent groups of knife blades Hair can enter the holes of the shaving foil perfectly in order to be subjected to a cutting process. There are a number of options for the design and arrangement of the individual knife blades, as will be explained in the following.

It has proven to be very advantageous if the two knife lamellae of a group are provided, at least in the apex region, with a bend directed towards one another and formed by at least one lamella section. In this way, it is very easily achieved that each of the two knife blades of a group, in accordance with the inclination direction of its angled section, is effective in one of the two directions of movement of the lower knife as a functionally flexible leading knife and in the other direction of movement of the lower knife as a functionally rigid cutting knife.

A particularly simple construction is obtained if the angle of each knife blade is formed by a single segment of the blade.

However, it has also proven to be advantageous if the angling of each knife lamella is formed by two lamella sections angled in opposite directions. This makes it possible to arrange the two knife blades, each forming a group, on the carrier side at a somewhat greater distance, which can be advantageous with regard to their mounting on the carrier.

Furthermore, it has proven to be advantageous if the angled lamella sections of the two knife lamellae forming a group lie in the apex region with prestress. This particularly favors a perfect interaction of the two knife blades forming a group in the course of a cutting process. In addition, the self-cleaning with regard to adhering hair particles results from the knife lamella sliding smoothly against one another in the course of the cutting process.

However, it also has advantages if the angled lamella sections lying in the apex area of the have a group of knife blades forming a group at their free ends. In this way, a knife blade effective as a leading knife, since it is not supported directly, is more resilient and bendable over a longer distance, which both favors the hair pulling effect.

As practice has shown, a particularly good interaction of the two knife blades forming a group is further obtained if the angled lamella sections of the two knife blades forming a group each have an acute angle of the order of magnitude with a plane perpendicular to the direction of movement of the lower knife of 10 ⁰ form.

However, it is also advantageous if the angled lamella sections in the apex region of the two knife lamellae forming a group each extend in a plane running perpendicular to the direction of movement of the lower knife. This makes it possible to utilize a larger circumferential area of the knife blades for the function as a leading knife.

Furthermore, it has proven to be advantageous if, in addition to each of the two knife blades of a group, depending on the direction of the group adjacent to it, a stiff support is provided, to which the blade blade in question at least opposes this direction when the lower knife moves partially created. In this way, it is achieved that each of the two knife blades of a group is supported in the direction of the reciprocating drive movement for the lower knife, in which it is intended to act as a cutting knife, which gives it such a rigidity that the cutting processes are particularly special run exactly and safely.

The desired elastic resilience of the knife blades can be achieved by appropriate choice of the hardness of their material and / or their thickness. In this context, it has proven to be very advantageous if the knife blades have at least one recess on the carrier side to increase their elastic flexibility. In this way, the blade slats can be largely optimally dimensioned with regard to their cutting properties, because their desired elastic compliance is achieved or increased by the provision of the recess.

In addition, practice has shown that particularly favorable conditions are obtained both with regard to the structural design and the cutting behavior if the distance between the two knife blades of a group on the carrier side is selected to be five times the thickness of a knife blade.

In the same context, it has also proven to be advantageous if the carrier-side distance between a knife blade of a group and the knife blade of the adjacent group lying next to it is selected in the order of magnitude of twice the carrier-side distance between the knife blades of a group.

The invention is explained in more detail below with reference to the drawings, in which some exemplary embodiments are shown, to which, however, it should not be restricted. Fig. 1 shows a lower knife with flat, stiff, paired knife blades arranged in section transverse to the direction of the reciprocating drive movement along the line II in Fig. 2. Fig. 2 shows the lower knife of Fig. 1 in a longitudinal section along the line II-II in Fig. 1. In Figs. 3a to 3d, the sequence of movements when cutting a hair with a lower knife according to Figs. 1 and 2 is shown schematically. Fig. 4 shows in the representation of Fig.1 and in section along the line IV-IV in Fig. 5, a lower knife with resilient knife blades, the two knife blades of a group each having an angled lamella section in the apex area. 5 shows the lower knife according to FIG. 4 in a longitudinal section along the line VV in FIG. 4. In FIGS. 6a to 6c, the sequence of movements when cutting a hair with a lower knife according to FIGS. 4 and 5 is shown schematically. Fig. 7 shows in longitudinal section a lower knife with flat, resilient knife blades, in addition to each of the two knife blades of a group, depending on the direction of the neighboring group, a rigid support is provided. 8a and 8b schematically show the sequence of movements when cutting a hair with a lower knife shown in FIG. 7. Finally, FIGS. 9a to 9f schematically show different exemplary embodiments of lower knives with knife blades, which are provided with different bends.

The lower knife shown in FIGS. 1 and 2 has two supports 1 and 2, which are formed by tubes and which carry curved knife blades 3. The knife fins 3 are pushed onto the carriers 1 and 2 at a distance from one another with corresponding bores, their position on the carriers being able to be fixed, for example, in that the tubes forming the carriers are widened from the inside after the knife fins are pushed on. However, there are also other possibilities for the construction of a lower knife having knife blades. For example, the knife blades can be embedded in a carrier made of plastic.

Such a lower knife is used in a known manner to interact with a curved screen shear film having a plurality of holes, it being pressed resiliently into its curvature. The lower knife is driven back and forth by the dry shaving apparatus, for which purpose it is provided with a coupling part, not shown, which can be fastened to the carriers 1 and 2, for example, by means of lugs extending between the knife lamellae. Such a lower knife should be provided with as many knife blades as possible, since each knife blade forms a cutting edge in both directions of the reciprocating drive movement, the shaving performance of the dry shaving apparatus increasing the more cutting edges are provided. There is a limit to this, however, in that the knife blades must not be arranged too close to one another, because otherwise they cover the holes provided in the sieve shaving foil, which serve to enter the hair, to such an extent that the hair is prevented from entering the holes Decrease in shaving performance. For the same reason, the choice of the thickness of the knife lamellae is particularly important interpretation to. In known lower knives of this type, for example, the thickness of the knife blades is 0.1 mm and the distance between two adjacent knife blades is 1.15 mm. Such a bottom knife can, for example, interact with a Siebscher film, the thickness of which is 0.05 mm and the holes have a diameter of 0.6 mm, the webs remaining between the holes having a width of 0.23 mm. As can be seen, hairs whose diameter can be assumed to be approximately 0.15 mm can enter the holes of the screen shaving foil without problems. The above-mentioned dimensioning information of known lower knives, like the following for lower knives according to the invention, are to be understood as orders of magnitude, deviations of + 50% are also to be included.

In a lower knife according to the invention, the knife blades 3 are grouped in pairs; 2, these groups are designated by 4. In the apex region of the knife blades indicated schematically in FIG. 1 by a dashed rectangle 5, the distance a between the two knife blades of a group 4 is smaller than the distance b between the knife blades facing one another of two adjacent groups 4. The knife blades 3 here are flat and rigid in itself, as is known per se. For a practical example it can be stated that the thickness s of a knife blade 3 with 0.1 mm, the distance a between the two knife blades 3 of a group 4 with twice the thickness of a knife blade and the distance b between the knife blades 3 facing one another of two neighboring ones Groups 4 with three times the distance a can be selected.

By arranging the knife blades in groups in this way, the cutting behavior of the lower knife is improved because the two blade blades 3 of a group 4, which are arranged next to one another at a smaller distance and thus follow one another rapidly in the course of movement, come into effect shortly after one another when cutting a hair, so that hair to be cut twice, shortly after one another, is cut off. Such a sequence of a cutting process is explained with reference to FIGS. 3a to 3d, wherein in these figures 6 denotes the skin from which a hair 7 protrudes which, as shown in FIG. 3a, penetrates a hole 8 in a sieve shear foil 9. The current direction of movement of the lower knife with its knife blades 3 is assumed in the direction of arrow 10. From Fig. 3a it can be seen how the hair 7 is clamped between the web 11 delimiting the hole 8 in the direction of movement 10 of the screen shear film 9 and the first knife blade 3 of a group 4 of two knife blades 3, also seen in the direction of movement 10, before it becomes Cutting process is coming. Fig. 3b shows the beginning of the cutting process, in which a local cutting gap is formed in the area of this hole 8, with curvature of the sieve shear foil 9 in the direction of the skin 6, and slightly pulls the aforementioned first knife blade 3 on the hair 7, the latter being curved and something is pulled out of his skin pocket. When the lower knife moves further, the first knife lamella 3 cuts off the hair end 12, as is indicated in FIG. 3c. After this cutting process, the cutting gap goes back and the hair 7 in the hole 8 straightens up again. At this point in time, however, the second knife lamella 3 of the group 4 of knife lamella 3 involved in this cutting process has reached the hair 7 even before it can withdraw from the hole 8 of the sieve shear film 9 due to skin tension, which can also be seen in FIG. 3c is. However, the second knife blade is now also able to cut off a further piece of the same hair, as shown in FIG. 3d, in which this further cut hair piece is designated by 13. As can be seen, each hair is thus cut twice in quick succession by the two knife blades 3 of a group 4 arranged at a shorter distance a, as a result of which better shaving performance is achieved. After this double cutting process is completed by a group 4 of knife lamellae 3, the following group 4 'seen in the direction of movement 10 comes from Knife blades 3 'in the area of the hole 8 of the screen shear film 9, where the above-mentioned cutting process has just taken place, as can also be seen in FIG. 3d. The larger distance b between the knife blades 3 and 3 'of the two adjacent groups 4 and 4' of knife blades lying next to one another ensures that the aforementioned hole 8 of the screen shaving foil 9 is still sufficiently free for the entry of another hair , before the subsequent knife lamellae 3 'of group 4' enter its area, which generally also applies in an analogous manner to the other holes 8 of the screen shear foil 9.

The paired arrangement of the knife blades in groups with a smaller distance between the two knife blades of a group and the sequence of the groups of knife blades with a greater distance means that on the one hand the two knife blades of a group cut the hair shorter and on the other hand the hair enters the holes in the screen shaving foil are not hindered, which is the case for the entire length of the lower knife, so that a very good shaving performance is obtained with such a lower knife.

4 and 5, the knife blades 3 are again arranged in pairs in groups 4. Here, however, knife blades are used which are designed to be elastically flexible in the two directions of the reciprocating drive movement for the lower knife, which can be done by the choice of their thickness and / or the hardness of the material used. In order to increase such flexibility or to achieve greater independence from the dimensioning of the knife blades, the individual knife blades here are also provided with a recess 14 on the carrier side. The resilience of the knife blades ensures that of the two knife blades 3 of a group 4, viewed in each of the two directions of movement, the front knife blade as a so-called leading knife and the rear knife blade as a so-called cutting knife is effective, which will be discussed in more detail below.

Furthermore, the blade lamellae 3 are designed such that in the area of the two supports 1 and 2 they have lamella sections 15 which are parallel to one another and run transversely to the direction of movement of the lower knife and are used for mounting the blade lamellae on the two supports, to which lamella sections 16 are connected towards the apex region 5 which are angled relative to sections 15.

The knife blades 3 are mounted on the supports 1 and 2 in such a way that the bends of the two knife blades 3 of a group 4 formed by the sections 16 are directed towards one another in the apex region 5. With a view to a particularly good functioning, these bends are carried out in such a way that the sections 16 form an acute angle of the order of 10 with a plane 17 running perpendicular to the direction of movement of the lower knife, as can be seen in FIG. 5. The arrangement of the knife blades 3 on the carriers 1 and? is further made such that the angled lamella sections 16 of the two knife lamellae 3 forming a group 4 lie in the apex region 5 with prestress. Here, the carrier-side distance c between the two knife blades 3 of a group 4 is selected to be smaller than the carrier-side distance d between the facing knife blades 3 of two adjacent groups 4. It has proven to be very favorable here if the distance c is of the order of five times the thickness s of a knife blade and the distance d in the order of twice the distance c is selected, the thickness s of a knife blade being 0.08 mm.

In the manufacture of such a lower knife, the knife fins which are punched out in an arc from a flat material are then provided with the bend formed by the finned section 16 and then in pairs, with bends directed towards each other, onto the tubes forming the supports 1 and 2 postponed and fixed on these with the corresponding distances c and d. The circumferential surfaces of all knife blades are then subjected to a common grinding process, thereby ensuring that the screen shear foil fits snugly against the entire circumferential area of the knife blades.

The operation of such a lower knife will now be explained in more detail with reference to FIGS. 6a to 6c, it being assumed that the current direction of movement of the lower knife again takes place in the direction of arrow 10. 6a shows the state before a cutting process, in which a hair 7 has passed through a hole 8 in the screen shear film 9 and already between the web 11 of the screen shear film 9 delimiting this hole 8 in the direction of movement 10 and the first knife blade 3 also seen in the direction of movement 10 a group 4 of two knife blades 3 is clamped. As the lower knife continues to move, the free end of section 16 of this first knife lamella 3 hooks onto hair 7 and pulls on it, section 16 of this knife lamella being bent towards the second knife lamella 3 of this group 4 due to its elastic flexibility. During this bending of the section 16 of the leading first knife lamella 3, its apex region slides along the apex region of the second knife lamella 3 of this group 4, this knife lamella also being bent in the same direction due to its elastic compliance, with the result that its angled section 16 is erected and stretched substantially straight. Here, the screen shear film 9 is locally deformed and shifted in the direction of the skin 6. In the process, the contact pressure between the screen shear film 9 and this second knife blade 3 increases, as a result of which it loses flexibility and thus becomes functionally a rigid cutting knife. The above-mentioned higher contact pressure between the screen shear film 9 and the second knife blade 3 also has the effect that in the present case practically no cutting gap is formed. These relationships are shown in Fig. 6b. At a Further movement of the lower blade now intersects the second, erected M _e sserlamelle 3 the hair end 12 of the hair 7 on, after which the force will be invisible to the two cutter lamellae 3 of the group 4, with the result that the portions 16 of the two cutter lamellae 3 under the action their elastic resilience return to their starting positions and thus the local deformation of the sieve shear foil 9 decreases again, as shown in FIG. 6c.

Such a cutting process cuts a hair shorter than is normally possible. Three factors are now relevant for this. The most important factor is that the first knife blade, which is moving in the direction of movement of the lower knife, pulls on the hair 7 before the actual cutting process, so that it is pulled out of its hair pocket a little and pulled further into the hole 8 of the screening shear film, resulting in a longer one Hair piece is available for the cutting process. Furthermore, an additional piece of hair 7 is pushed into the hole 8 of the sieve shear film by the local deformation of the sieve shear film 9 in the region of the hole 8, in which the film is pressed towards the skin, and is thus also subjected to the cutting process. Finally, due to the increased contact pressure between the screen shear film 9 and the second knife blade 3 cutting the hair, there is practically no cutting gap, as a result of which the hair is also cut off a little shorter. In this way, a very good shaving performance is obtained with such a lower knife.

As can be seen, the blade blade 3 lying in front in the direction of movement of the lower blade in a group 4 of blade blades 3 is thus a functionally flexible leading blade and thus a hair pulling element and the blade blade 3 following in this direction of motion of the lower blade, which is only effective of the leading knife gains in stiffness, effective as a stiff cutting knife in its function. This ensures that the lower knife is equally effective in its two directions of movement. It is the construction of the lower knife is very simple, since only two knife lamellae fulfill these functions and a separate cutting knife does not have to be assigned to a separate cutting knife in each of the two directions of movement, as is known per se.

The fact that in the present exemplary embodiment the angled lamella sections 16 of the two knife lamellae 3 forming a group 4 lie against one another in the apex region 5 with a prestress, a very good interaction of the two knife lamellae in the interplay is obtained as a leading knife and as a cutting knife. However, this mutual prestressing also achieves a good cleaning effect in the apex area of the two knife lamellae of hair particles which may adhere there, since the knife lamella, which is effective as the lead knife, pushes under force on the knife lamella, which then acts as the cutting knife.

It should also be mentioned that the two knife lamellae 3 forming a group 4 of course only lie against one another with their angled sections 16 exactly at the apex. Starting from this apex, the distance between these two knife blades increases on both sides until the end of the bend on the support side is reached, after which the two knife blades with their sections 15 run parallel to one another at a distance c. The result of this is that the mode of operation of the knife blades 3 as a leading knife and hair pulling element is essentially limited to the apex region 5 of the sections 16 of the knife blades, but this does not constitute a significant disadvantage. The area mainly involved in a shave is, because of the usual handling of a dry shaver, the apex area, but where the desired functionality is guaranteed.

In addition, a further advantageous effect occurs here, which is due to the fact that the distance between the two knife blades 3 of a group 4 is chosen to be smaller than the distance between the two facing knife blades 3 of two adjacent groups 4. To the extent that the distance between the two knife blades 3 of a group 4 increases in the circumferential direction on both sides of the apex area, their elastic compliance also decreases, which has the consequence that both knife blades are located laterally from the apex area act as a rigid cutting knife and consequently those conditions occur when cutting the hair, which have been described in connection with the embodiment of FIGS. 1 and 2. This means that in the circumferential areas of the knife lamellae adjoining the apex area, they cut the hair entering the holes in the screening shear film twice in quick succession, so that in these areas the hair is cut shorter than usual. The greater distance between the mutually facing knife blades of two adjacent groups of knife blades again ensures that the penetration of the hair into the holes in the screen shaving foil is not hindered. Seen overall, a substantial improvement in shaving performance is obtained with such a lower knife.

In the exemplary embodiment according to FIG. 7, resilient knife blades 3 are used again, which are, however, of flat design here. Two of these knife blades 3 each again form a group 4, the distance e between the two knife blades 3 of a group 4 being chosen smaller than the distance f between the knife blades 3 facing one another of two adjacent groups 4. As a dimensioning example, it can be stated that the thickness s of a knife blade is 0.08 mm, the distance e can be selected approximately equal to five times the thickness s and the distance f approximately equal to twice the distance e. In the present exemplary embodiment, in addition to each of the two knife blades 3 of a group 4, each in the direction of view of the group 4 adjacent to it, a stiff support 18 is provided, to which the knife blades 3 in question move when the Lower knife at least partially applied opposite to this line of sight. In this way, each of the two knife blades 3 of a group 4 is resilient in the direction of the adjacent knife blade of the same group, whereas each of the two knife blades 3 of a group 4 is rigid in the direction of the group 4 adjacent to it, since the support adjacent to it 18 counteracts yielding in this direction. It is thereby achieved that here again the two knife blades 3 of a group 4, depending on the current direction of movement of the lower knife, act as a leading knife forming a hair pulling element and the other time as a cutting knife. In the present exemplary embodiment, the supports 18 are formed by strip-shaped parts which are provided with bores corresponding to the knife lamellae, so that, like the knife lamellae, they can be pushed onto the carrier of the lower knife formed by tubes, of which only the carrier 2 is visible in FIG. 7 are. After appropriate positioning of the knife blades 3 and the supports 18 with respect to their mutual positions, they are fixed on the carriers. The rigidity that a knife blade receives when it is applied to the adjacent support can be determined by appropriate dimensioning of the support, for which the choice of material and shape are decisive. Of course, such supports can also be designed differently, such as, for example, as spacers which are inserted between the knife blades.

The mode of operation of such a lower knife is illustrated with the aid of FIGS. 8a and 8b. 8a again shows a hair 7 which has penetrated into a hole 8 of a sieve shear film 9 and which is already between the web 11 of the sieve shear film 9 delimiting this hole 8 in the direction of movement 10 of the lower knife and the first knife lamella 3 of a group 4 which also runs in this direction of movement is clamped by two knife blades 3. When the lower knife is moved further, the free end of the leading end lying in the apex area hooks again a first knife blade 3 into the hair 7, after which this knife blade 3 bends in the direction of the succeeding second knife blade 3 and comes to rest on the same, at which time this second knife blade 3 also reached the hair 7, as shown in FIG. 8b shows. During this bending of the leading first blade lamella 3, it pulls on the hair 7, so that it is pulled out of its hair pocket somewhat and pulled further into the hole 8 of the screening shear foil. In this way, the leading end in the current direction of movement of the lower blade knife blade 3 is re-forming as a a Haarzugelement V _o rlaufmesser effective. When the lower knife moves further, the second knife lamella 3 then initiates the cutting process, since when viewed in this direction of movement, due to its contact with the support 18 adjacent to it, it is essentially stiff and thus acts as a cutting knife. In this way, longer pieces of hair are cut off than is known per se from the mode of operation of a leading knife.

In the present exemplary embodiment, a knife blade which acts as a leading knife is yielded over a distance determined by the distance e between the two knife blades 3 of a group 4, since the knife blade bends up to the knife blade which forms the cutting knife and follows it. In this way, there is a longer hair pulling area during which the leading knife pulls on the hair and pulls it out of the hair pocket, resulting in a shorter cut off of the hair. As in the exemplary embodiment according to FIGS. 4 and 5, such an operation of the two knife blades 3 forming a group 4, namely on the one hand as a lead knife and on the other hand as a cutting knife, will mainly occur in the apex region of the knife blades, since the blade blades are most flexible there. However, since in the present exemplary embodiment the two knife blades 3 forming a group 4 are not in direct contact with one another in their starting position, the knife blade which is in each case effective as a leading blade can also give way in the circumferential direction of the apex area on both sides a little further away and accordingly act as a lead knife. In the additional lateral circumferential areas of the knife blades 3, the two knife blades forming a group then act again as two rigid cutting knives, which come into effect shortly after one another, due to their increasing stiffness and their smaller spacing from one another, so that in these areas too, the hairs are cut off shorter takes place without the entry of hair into the holes of the sieve shaving foil being hindered because the distance between the facing knife blades of two adjacent groups of knife blades is again greater than the distance between the two knife blades of a group.

9a to 9f, further exemplary embodiments for lower knives with resiliently flexible knife blades are discussed. In these exemplary embodiments, it is assumed that the knife blades with their carrier-side sections 15 are arranged at equal distances g from one another on the carrier 1 indicated by a single block. Of course, however, all of these exemplary embodiments can also be carried out with correspondingly different carrier-side distances between the knife blades. Any support structures can also be used. Supports can also be provided in addition to the knife lamellae, as in the exemplary embodiment according to FIG. 7. The exemplary embodiments dealt with here are therefore only intended to show further embodiments which are possible in principle with regard to the design and arrangement of the knife blades.

According to Fig. 9a, the two knife blades 3 of a group 4 in the apex area 5 are provided with a mutually directed angled portion which adjoins the blade portion 15 on the support side and is formed by a single blade portion 16, analogously to the exemplary embodiment according to FIGS. 4 and 5. Here, however, the angled lamella sections 16 face each other a plane 17 running perpendicular to the direction of movement of the lower knife has a greater inclination, which has the consequence that the carrier-side distances of the knife blades forming a group can be chosen to be larger, as a result of which the assembly of such a lower knife is facilitated. As can be seen in FIG. 9a, the conditions here were such that both the carrier-side distances between the two knife blades 3 forming a group 4 and the distances between the knife blades 3 facing each other of two adjacent groups 4 are of the same size. Through the angled sections 16 it is nevertheless achieved that, seen from the carrier 1 towards the apex of the knife blades 3, the distance between the two knife blades 3 of a group 4 is smaller than the distance between the knife blades 3 of two adjacent groups 4 facing one another again provided that the angled lamella sections 16 of the two knife lamellae 3 forming a group 4, which lie directly in the apex region, bear against one another with prestress. Such a lower knife again shows a mode of operation as was explained using the exemplary embodiment according to FIGS. 4 and 5.

The exemplary embodiment according to FIG. 9b shows a similar arrangement to FIG. 9a, but the angled lamella sections 16 of the two knife lamellae 3 forming a group 4 lying in the apex region are at a distance h from one another at their free ends, which is analogous to the exemplary embodiment according to FIG. 7 What is achieved is that the area for the resilient adjustability of a knife blade effective as a leading knife is larger and thus the hair pulling effect is increased.

In the exemplary embodiment according to FIG. 9c, the angling of each knife lamella is formed by two sections 19 and 20 angled in opposite directions, the angled lamella sections 19 of the two knife lamellae 3 forming a group 4 in the apex region each having a point 17 with a plane 17 running perpendicular to the direction of movement of the lower knife Angles in sizes Form an order of 10 ° and rest against each other with pre-tension. As a result of the opposite bend, the sections 20 are then inclined correspondingly more with respect to the plane 17. In this way, it is possible to arrange the two group of knife blades 3 on the carrier side with their sections 15 at a greater distance from one another, but nevertheless to obtain sections 19 in the apex region of the knife blades, which run at a relatively acute angle with respect to plane 17, which has proven to be advantageous for the interaction of the two knife lamellae forming a group 4, in each of which one acts as a leading knife and the other as a cutting knife.

9d shows an arrangement of the knife blades 3 analogous to FIG. 9c, but the angled blade sections 19 of the two knife blades 3 forming a group 4, which are located in the apex region, run with their free ends at a distance from one another, just as in the embodiment according to FIG. 9b.

In the exemplary embodiment according to FIG. 9e, analogously to the exemplary embodiment according to FIG. 9c, the wiping relation of the knife lamellae is again formed by two lamella sections 19 and 20 angled in opposite directions, but here the lamella sections 19 of the two knife lamellae 3 forming a group 4 lie in the apex region each lie in a plane 17 running perpendicular to the direction of movement of the lower knife. Again, the lamella sections 19 rest against one another in the apex region with a pretension. Accordingly, the two mutually parallel lamella sections 19 of the two knife lamellae 3 forming a group 4 adjoin one another flatly. When a knife lamella 3 functions as _a leading knife, its section 19 then moves along the section 19 of the other knife lamella 3 of the relevant group 4 of knife lamellae 3, which acts as a cutting knife. With such a configuration of the lamella sections 19, the functional area for a leading knife then extends over the entire circumferential area of the sections 19, although only a smaller adjustment path is obtained for the knife blade which acts as a leading knife. An enlargement of this adjustment path for the knife blade acting as the leading knife can be obtained again if the angled sections 19 of the two knife plates 3 forming a group 4 run at a distance h from one another, as is shown by the exemplary embodiment according to FIG. 9f.

As can be seen from the above, there are a number of modifications of the exemplary embodiments described, without thereby leaving the scope of the invention.

Claims (14)

1. Back and forth drivable bottom knife for dry shavers, which is intended to interact with a sieve shaving foil and has a number of spaced-apart, on at least one support, curved knife blades, at least the distances between a knife blade and the two neighboring knife blades being unequal are large, characterized in that the knife blades are grouped in pairs, the distance between the two knife blades of a group being at least smaller in the apex region of the knife blades than the distance between a knife blade of this group and the knife blade of a neighboring group lying next to it. 2. Lower knife according to claim 1, characterized in that the paired knife blades are flat and rigid in themselves. 3. lower knife according to claim 1, characterized in that the paired knife blades in at least one of the two directions of the reciprocating drive movement for the lower knife are designed to be resilient, with the two knife blades of a group, seen in each of the two directions of movement, in each case the front knife lamella is effective as a feed knife which is flexible in its function and the rear knife lamella is effective as a cutting knife which is rigid in its function. 4. Lower knife according to claim 3, characterized in that the two knife blades of a group are provided at least in the apex area with a mutually directed, formed by at least one lamella section. 5. Lower knife according to claim 4, characterized in that the bend of each knife blade is formed by a single lamella section. 6. Lower knife according to claim 4; characterized in that the bending of each knife blade is formed by two mutually angled blade segments. 7. Lower knife according to one of claims 4 to 6, characterized in that the angled lamella sections lying in the apex region of the two knife lamellae forming a group bear against one another with prestress. 8. Lower knife according to one of claims 4 to 6, characterized in that the angled lamella sections lying in the apex region of the two knife lamellae forming a group are spaced apart from one another at their free ends. 9. Lower knife according to one of claims 4 to 8, characterized in that the angled lamella sections lying in the apex region of the two grouping knife lamellae each form an acute angle of the order of 10 ° with a plane running perpendicular to the direction of movement of the lower knife. 10. Lower knife according to one of claims 6 to 8, characterized in that the angled lamella sections lying in the apex region of the two knife lamellae forming a group each extend in a plane running perpendicular to the direction of movement of the lower knife. 11. Lower knife according to one of claims 3 to 10, characterized in that in addition to each of the two knife blades of a group, depending in the direction of view to the group adjacent to it, a rigid support is provided, to which the knife blade in question moves of the lower knife at least partially against this line of sight. 12. Lower knife according to one of claims 3 to 11, characterized in that the knife blades have at least one recess on the carrier side to increase their flexibility. 13. Lower knife according to one of the preceding claims, characterized in that the carrier-side from stood between the two knife blades of a group in the order of five times the thickness of a knife blade. 14. Lower knife according to one of the preceding claims, characterized in that the carrier-side distance between a knife blade of a group and the knife blade of the adjacent group lying next to it is selected in the order of magnitude of twice the carrier-side distance between the two knife blades of a group.

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