EP0086536B2 - Cutting-blade assembly for reciprocating dryshaver - Google Patents

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 lamellae are not the same size and, when the knife lamellae are grouped in pairs, at least in the apex area of the knife lamellae the distance between the two knife lamellae of this group and the knife lamella of an adjacent group lying next to it.

In a lower knife of this type known from JP-GM 51892/1983, all knife lamellae are stiff and flat, both knife lamellae of each group acting as cutting knives, whereby each hair is cut off twice in quick succession and therefore results in improved shaving performance compared to other lower knife designs .

The invention has set itself the task of further improving a lower knife of the type mentioned in terms of the shaving performance that can be achieved with it. According to the invention, this object is achieved in that, in a manner known per se, the knife blades are designed to be resilient in the at least one of the two directions of the reciprocating drive movement for the lower knife, of the two knife blades of a group, in each of the seen in both directions of movement, in each case the front knife blade acts as a flexible forward knife in its function and the rear knife blade acts as a stiff cutting knife in its function, and that the two knife blades of a group are provided with an angulation directed towards one another and formed by at least one slat section, at least in the apex region are.

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 from AT-PS 333.151, AT-PS 360.375 or also from US-PS 3,088,205 and the DE-OS 2.850.827 emerges.

In the lower knife according to the invention, the function of the slat angle in each slat group leading to a reduced slat distance in the area of the slat apex in cooperation with the elastic design of the slats, depending on the direction of movement of the lower knife, is one of the two knife slats of a group as a flexible leading knife and the other Knife blade favors as a rigid cutting knife, as will be explained in more detail later. On the other hand, with the same distance between the knife blades on the carrier side, the space between adjacent groups of knife blades in the apex area is enlarged, which facilitates the entry of the hair into the holes in the screen shaving foil, which likewise contributes to improving the shaving performance.

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 blade lamellae which form a group are arranged so as to lie against one another with pretension. 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.

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 ° 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.

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 in order to increase their elastic resilience. In this way, the knife 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.

Furthermore, practice has shown that especially Favorable conditions can be obtained both with regard to the construction 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. Figure 1 shows a section along the line I-I in Figure 2, a lower knife with resilient knife blades, the two knife blades of a group each having an angled lamella section facing each other in the apex area. Figure 2 shows the lower knife of Figure 1 in a longitudinal section along the line 11-11 in Figure 1. In Figures 3a to 3c, the sequence of movements when cutting a hair with a lower knife according to Figures 1 and 2 is shown schematically. Figures 4a to 4f schematically show different embodiments of lower knives with knife blades, which are provided with different angles.

In the embodiment according to FIGS. 1 and 2, the knife blades 3 are arranged in pairs in groups 4. 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 choosing 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 acts as a so-called leading knife and the rear knife blade as a so-called cutting knife, 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 toward one another in the apex region 5. With a view to 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. 2. The arrangement of the knife blades 3 on the supports 1 and 2 is in this case further made such that the angled blade segments 16 of the two blade blades 3 forming a group 4 lying in the apex region 5 bear against one another 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 advantageous 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 lamellas punched out from a flat material in an arcuate manner are subsequently formed with the lamella section 16. Provide bend and then in pairs, with bends facing each other, pushed onto the tubes forming the beams 1 and 2 and fixed on them with the corresponding distances c and d. The circumferential surfaces of all knife blades are then subjected to a common grinding process, which ensures that a sieve shear foil fits snugly over 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. 3a to 3c, it being assumed that the current direction of movement of the lower knife again takes place in the direction of arrow 10. 3a 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. When the lower knife moves further, the free end of the section 16 of this first knife blade 3 hooks onto the hair 7 and pulls on it, the section 16 of this knife blade being bent towards the second knife blade 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 erected and im we is being stretched considerably. Here, the screen shear foil 9 is locally deformed and shifted in the direction of the skin 6. The contact pressure between the screen shear film 9 and this second knife blade 3 increases, as a result of which it loses its 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 lamella 3 also means that, in the present case, practically no cutting gap is formed. These relationships are shown in Fig. 3b. When the lower knife moves further, the second, upright knife blade 3 now cuts the hair end 12 off the hair 7, after which the force acting on the two knife blades 3 of this group 4 ceases, with the result that the sections 16 of the two knife blades 3 are under the action resume their initial positions due to their elastic compliance and thus the local deformation of the screen shear foil 9 also decreases, as shown in FIG. 3c.

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. The construction of the lower knife is very simple, since only two knife blades fulfill these functions and it is not necessary to assign a separate leading knife to 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. Through this mutual. Preload is also achieved in the apex area of the two knife blades, a good cleaning effect of hair particles which may be adhering there, since the knife blade, which acts as the lead knife, pushes along under the force of the knife blade, 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 carrier side is reached, after which the two knife blades with their sections 15 then run coparally to one another. The result of this is that the mode of operation of the knife blades 3 as a preliminary 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 knife blades 3 facing one another of two adjacent groups 4. To the extent that there is on both sides of the apex area, the distance between the two knife blades 3 of a group 4 is increased in the circumferential direction, namely their elastic flexibility also decreases, which has the consequence that both knife blades act laterally from the apex area as rigid cutting knives. 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.

4a to 4f are further exemplary embodiments of lower knives with ela resilient knife blades discussed. In these exemplary embodiments, it is assumed that the knife lamellae 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. 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.

4a, the two knife lamellae 3 of a group 4 in the apex region 5 are provided with an angled connection which adjoins the lamella section 15 on the support side and is formed by a single lamella section 16, analogously to the exemplary embodiment according to FIGS. 1 and 2 Here, however, the angled lamella sections 16 have a greater inclination with respect to a plane 17 running perpendicular to the direction of movement of the lower knife, with the result that the carrier-side distances of the knife lamellas forming a group can be selected to be larger, thereby facilitating the assembly of such a lower knife . As can be seen from FIG. 4a, 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 one another 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 facing one another of two adjacent groups 4. Next it is again provided that the angled lamella sections 16 of the two knife lamellae 3 forming a group 4 lie directly in the apex region with prestress. Such a lower knife again shows a mode of operation as it was explained using the exemplary embodiment according to FIGS. 1 and 2.

The exemplary embodiment according to FIG. 4b shows an arrangement similar to FIG. 4a, however the angled lamella sections 16 of the two knife lamellae 3 forming a group 4 lying in the apex region have a distance h from one another at their free ends, as a result of which the area for the resilient adjustability of a knife blade effective as a leading knife is larger and the hair pulling effect is also increased. In the exemplary embodiment according to FIG. 4c, 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 each having a plane 17 which is perpendicular to the direction of movement of the lower knife Form angles of the 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.

FIG. 4d shows an arrangement of the knife blades 3 analogous to FIG. 4c, 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 exemplary embodiment according to FIG. 4b.

In the exemplary embodiment according to FIG. 4, analogous to the exemplary embodiment according to FIG. 4c, the angling 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 are in each case in the apex region 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 prestress. 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 Whole circumferential area of the sections 19, but 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. 4f.

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 (10)

1. A reciprocatingly drivable cutter for dry- shaving apparatuses, which cutter is adapted to co-operate with a shear foil (9) and comprises a plurality of spaced-apart adjacent arcuate cutter lamellae (3) arranged on at least one support (1, 2), at least the distance between one cutter lamella and the two adjacent cutter lamellae being unequal and, when the cutter lamellae are arranged in pairs, the distance between the two cutter lamellae of one pair (4) being smaller, at least in the apex area (5) of the cutter lamellae, than the distance between one cutter lamella of said pair and the adjacent cutter lamella of an adjacent pair, characterized in that, in a manner known per se, the cutter lamellae (3) are constructed to be elastically flexible in at least one of the two directions of the reciprocating cutter- drive movement, the leading cutter lamella of the two cutter lamellae (3) of a pair (4), viewed in each of the two directions of movement, acting as a functionally elastic hair-pulling blade and the trailing cutter lamella acting as a functionally rigid cutting blade, and in that at least in the apex area (5) the two cutter lamellae (3) of a pair (4) comprise angular portions which are oriented towards each other and which are each formed by at least one lamella portion (16 ; 19, 20).

2. A cutter as claimed in Claim 1, characterized in that the angular portion of each cutter lamella (3) is formed by a single lamella portion (16).

3. A cutter as claimed in Claim 1, characterized in that the angular portion of each cutter lamella (3) comprises two oppositely inclined lamella portions (19, 20).

4. A cutter as claimed in any one of the Claims 1 to 3, characterized in that in the apex area (5) the angular lamella portions (16 ; 19) of the two cutter lamellae (3) forming a pair (4) are urged against each other under pre-load.

5. A cutter as claimed in any one of the Claims 1 to 3, characterized in that in the apex area the angular lamella portions (16 ; 19) of the two cutter lamellae of a pair are spaced from each other at their free ends.

6. A cutter as claimed in any one of the Claims 1 to 5, characterized in that in the apex area the angular lamella portions (16 ; 19) of the two cutter lamellae (3) of a pair (4) are disposed at an acute angle of the order of magnitude of 10° relative to a plane (17) perpendicular to the directions of movement of the cutter.

7. A cutter as claimed in any one of the Claims 3, 4 or 5, characterized in that in the apex area the angular lamella portions (19) of the two cutter lamellae (3) of a pair (4) each extend in a plane (17) perpendicular to the direction of movement of the cutter.

8. A cutter as claimed in any one of the Claims 1 to 7, characterized in that at the side of the support the cutter lamellae (3) are formed with at least one cut-out -(14) in order to increase their flexibility.

9. A cutter as claimed in any one of the preceding Claims, characterized in that the distance (c) between the two cutter lamellae (3) of a pair (4) is of the order of magnitude of five times the thickness (s) of one cutter lamella.

10. A cutter as claimed in any one of the preceding Claims, characterized in that at the side of the support the distance (d) between a cutter lamella (3) of a pair (4) and the adjacent cutter lamella (3) of the adjacent pair (4) is of the order of magnitude of two times the distance (c) between the two cutter lamellae (3) of a pair (4).

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