EP0189335B1 - Knife unit for a dryshaver and method for sharpening and assembling such a unit - Google Patents

Abstract

Arcuate shaver knives (1) maintained in parallel spaced relation and in alignment along a support (20) have inwardly-opening notches (5, 6) located opposite to two parallel longitudinal grooves (21, 22) formed in the support. The notches (5, 6) are locked on two locking-pins (30) which engage within the space formed between the grooves (21, 22) and the notches (5, 6) of the shaver knives.

Description

The present invention relates to a knife unit with knives for razor with grid and support one on which these knives are mounted, this support having slots perpendicular to the longitudinal direction of the support, in which the knives are positioned and keeping the knives spaced parallel to each other and aligned in the longitudinal direction of this support, the knives having an arcuate shape and a certain elasticity and comprising fixing means which cooperate with locking means which make it possible to mount these knives on the support.

The invention also relates to the method for sharpening the knives forming part of the knife unit and the method for mounting them on the support of the knife unit of the razor.

In known electric razors, the knives mounted on the support are covered by a fixed grid comprising a multitude of small openings, under which the cutting edge of the knives moves. These knives are all moved at the same time in an alternating movement of translation of the support, which is controlled by an electric motor.

In known embodiments, the knives are assembled on a support by crimping or overmolding when this support is made of plastic.

The knives mounted on the support are sharpened on a cylindrical grinder. This operation leaves a burr on the cutting edges of the knives.

These cutting edges are then grinded by means of a complex and expensive installation to eliminate the aforementioned burr.

According to DE-C-961 866 knives for grating razors, mounted on a support which keeps the knives spaced, parallel and spaced from each other and aligned in the longitudinal direction of this support. These knives have an arched shape and a certain elasticity. The support has slots perpendicular to the direction of the support in which the knives are positioned. The knives are separated by shims and are crossed by assembly pins.

To obtain perfect alignment of the cutting edges of the knives, it is necessary to sharpen these edges after mounting the knives on their support. This operation has the drawbacks already mentioned above.

The object of the present invention is to create a knife unit with knives for grating razors and a support for holding them, thanks to which it is possible to position these knives with great ease and precision on the support and d '' avoid the costly operation of eliminating the burr which remains after the rectification of the cutting edge of the knives.

According to the invention, the knife unit comprising the knives for grating razor and the support on which these knives are mounted, is characterized in that the knives comprise near each end of the arc, a notch opening towards the inside of the arc, in that the support has two longitudinal grooves, parallel to the longitudinal direction of the support, the notches of the knives being arranged opposite these grooves, and in that said notches are. resiliently locked on two pins engaged in the space between the two grooves and the notches of the knives.

This system of fixing by pins, retained in longitudinal grooves formed in the support and locking the knives to the support by the notches formed in them, allows a very simple mounting of these knives on the support, while guaranteeing an extreme precision for the position of the knives on the support.

The notches in the knives can be replaced by bosses locked to V-section profiles engaged in the longitudinal grooves of the support.

Furthermore, this fixing of the knives on the support by means of pins allows the implementation of a sharpening process which avoids the formation of burrs on the cutting edges.

According to this method, in accordance with the invention, the knives are placed on a mandrel having two longitudinal and parallel grooves, spaced from one another by a distance equal to the distance between the two grooves of the knife support, by positioning the notches or bosses of this knife opposite these grooves, force is engaged two pins or profiles of appropriate section in the space between each groove of the mandrel and the adjacent notches or bosses of the knives, the knives are clamped against each other, the mandrel is made to rotate about its axis and a stack of knives stacked and clamped on the mandrel is applied against the outer surface so as to sharpen all of the knives.

The fact that the knives are clamped against each other prevents the formation of burrs on the cutting edges.

Furthermore, since the knives are precisely positioned on the mandrel, by means of two pins spaced the same distance as those intended to position the knives on the knife support, it is ensured that the knives are positioned on this support with the same high precision as on the sharpening mandrel.

According to another aspect of the invention, in order to mount the sharpened knives on the knife support, the sharpened knives are removed from the chuck by releasing the pins or said profiles, these knives are placed on the support, keeping the order in which these knives were placed on the sharpening mandrel, force the two pins or two profiles in the space between each longitudinal groove of the support and the adjacent notches of the knives.

Since the order of the knife position is maintained, the cutting edges of the knives are perfectly aligned with each other when these knives are placed on the knife holder.

Other features and advantages of the invention will appear in the description below.

• - la figure 1 est une vue en plan du mandrin sur lequel sont montés les couteaux en vue de leur affûtage,
• - la figure 2 est une vue avec coupe longitudinale partielle du mandrin, en position sur un dispositif d'affûtage représenté en pointillés.
• - la figure 3 est une vue en coupe suivant le plan I11- III de la figure 2,
• - la figure 4 est une vue de côté, avec demi- coupe longitudinale du support de couteaux, des couteaux et d'une goupille avant la mise en place de ceux-ci sur le support,
• - la figure 5 est une vue suivant la flèche F de la figure 4,
• - la figure 6 est une vue en élévation du support portant les couteaux, recouvert par la grille qui est en partie arrachée,
• - la figure 7 est une vue en bout du support portant les couteaux,
• - la figure 8 est une vue en coupe suivant le plan VII - VII de la figure 6,
• - la figure 9 est une vue de dessus du support portant les couteaux, et
• - la figure 10 est une vue en plan d'une variant de couteaux,
• - la figure 11 est une vue analogue à la figure 7, concernant un autre mode de fixation des couteaux sur le support.

In the appended drawings, given by way of nonlimiting examples:

• FIG. 1 is a plan view of the mandrel on which the knives are mounted with a view to sharpening them,
• - Figure 2 is a view with partial longitudinal section of the mandrel, in position on a sharpening device shown in dotted lines.
• FIG. 3 is a sectional view along the plane I11-III of FIG. 2,
• FIG. 4 is a side view, with longitudinal half-section of the knife support, of the knives and of a pin before they are placed on the support,
• FIG. 5 is a view along the arrow F in FIG. 4,
• FIG. 6 is an elevation view of the support carrying the knives, covered by the grid which is partially cut away,
• FIG. 7 is an end view of the support carrying the knives,
• FIG. 8 is a sectional view along the plane VII - VII of FIG. 6,
• FIG. 9 is a top view of the support carrying the knives, and
• FIG. 10 is a plan view of a variant of knives,
• - Figure 11 is a view similar to Figure 7, concerning another method of fixing the knives on the support.

We will first describe, with reference to Figures 1 to 3, the method of sharpening razor knives, according to the invention.

These knives 1 are made of hardened steel and have the general shape of an arc of a circle (see FIG. 3). These knives 1 are constituted by a curved blade having a substantially constant deformation along its curvature. These knives 1 have near each end of the arc a notch 5, 6 opening towards the inside of the arc.

These knives 1 are placed on a cylindrical mandrel 2, having two longitudinal and parallel grooves 3, 4 extending along two diametric generatrices of the mandrel 2.

The knives 1 are positioned on the mandrel 2 so that the notches 5, 6 of the knives are substantially opposite the logitudinal grooves 3, 4 of the mandrel 2.

Then, by force, in the space between each longitudinal groove 3, 4 of the mandrel 2 and the adjacent notches 5, 6 of the knives, a pin 7. The two pins 7 (one on each side) thus ensure precise positioning. knives 1 on the mandrel 2.

One end (see Figures 1 and 2) of the mandrel 2 carries a fixed support ring 8. The other end of this mandrel 2 carries a movable ring 9 against which a nut 10 is screwed.

The knives 1 stacked on the mandrel 2 are tightened against each other between the rings 8 and 9 by means of the nut 10.

The opposite ends of the mandrel 2 have centering holes 11, 12 conical, making it possible to place this mandrel between two conical points 13,14 shown in dotted lines (see FIG. 2), arranged along an axis X - X 'constituting the axis d drive in rotation of a grinder-sharpener.

The tip 14 is adjacent to a rotary plate 15 also shown in dotted lines in FIG. 2, carrying a finger 16 in abutment against a lever 17 fixed to the nut 10 of the mandrel 2. The rotary plate 15 thus rotates the mandrel 2 via finger 16 and lever 17.

The mandrel 2 is driven by an alternative movement of translation along the axis X - X 'which is controlled by means of a device not shown.

On the cylindrical outer surface defined by the stacking of the knives 1, a grinding wheel 18 mounted in rotation about an axis Y - Y 'is supported. This grinding wheel 18 rotates in the same direction as that of the mandrel 2. This grinding wheel 18 thus sharpens all of the knives 1. Since these are clamped against each other, no burr is formed on the edge cutting the arc of these knives 1.

We will now describe the method of mounting the knives 1 sharpened on the razor support.

In the embodiment of Figures 4 to 9, the support 20 made of plastic has on each side two longitudinal grooves 21, 22 parallel to the longitudinal direction of the support.

This support 20 comprises a protruding middle rib 23 and extending in the longitudinal direction of the support. The upper end of this rib 23 comprises (see FIG. 4) slots 24 perpendicular to the support, regularly spaced, intended to each receive a knife 1.

This support 20 also includes two parallel wings 25, 26 (see FIG. 5) located in a plane perpendicular to the middle rib 23.

It can be seen in FIG. 4 that each wing 25 or 26 comprises regularly spaced slots 27 which, like the slots 24 are each intended to receive a knife 1. There exists for each knife 1 a slot 24 and two slots 27 arranged in a plane perpendicular to the longitudinal axis of the support 20, intended to receive a knife, the two slots 27 being arranged at 90 ° on either side of the slot 24.

We also see in Figure 5 that the wings 25 and 26 border up, the grooves longitudinal 21 and 22 formed on the sides of the support 20.

FIG. 4 shows on the other hand that the support 20 comprises on its lower face cells 28, 29 of which at least one is intended to receive a finger (not shown) driven by a motor to move the support 20 according to a movement translation alternative directed in the direction of its longitudinal axis.

To set up the sharpened knives 1 on the support 20, we start by removing these knives from the mandrel 2 by releasing the two pins 7 after having unscrewed the nut 10.

The knives 1 are placed on the support 20 by engaging each of them in a slot 24 and two slots 27 and keeping the order in which these knives were placed on the sharpening mandrel 2. Then two pins are forcibly engaged 30 (see FIGS. 4, 6, 7 and 8) in the spaces between each longitudinal groove 21 and 22 of the support 20 and the adjacent notches 5, 6 of the knives 1. Thus, the notches 5 and 6 of the knives 1 are locked to the two pins 30 which are themselves retained in the grooves 21 and 22 of the support 20.

Since the distance between the two pins 30 engaged in the grooves 21 and 22 of the support 20 is the same as the distance between the pins 7 (whose diameter is equal to that of the pins 30) which were used to position the knives 1 on the sharpening mandrel 2 and that the order of the position of the knives 1 on the support 20 is the same as on the mandrel 2, the knives 1 are placed on the support 20 with very high precision. Thus the cutting edges 1a which have been sharpened are situated on a cylindrical surface C (shown in phantom in FIG. 6) which corresponds exactly to the cylindrical surface in which these edges were arranged when the knives 1 were on the mandrel 2 after sharpening.

Since the surface in which the edges lie after sharpening may be slightly frustoconical due to the tolerances of grinding, this surface is perfectly respected after mounting the knives 1 on the support 20, so that the edges la in all cases perfectly aligned with each other, as seen in Figures 6 and 9.

Once the knives 1 mounted on the support 20, the latter can be placed directly in the razor, without it being necessary to correct the cutting edges 1a of these knives, given that these have no burr.

It then suffices to cover the support 20 carrying the knives 1 by the grid 31 (see FIG. 6).

Of course, the operations consisting in removing the knives 1 from the mandrel 2 and then placing these knives 1 on the razor support 20, while keeping the order of the knives 1 can be executed in a fully automatic manner using a machine operating at high speed to allow mass production.

Of course, the invention is not limited to the examples which have just been described and numerous modifications can be made to them without departing from the scope of the invention.

Thus the cutting edge of the knives can have a shape other than that of an arc of a circle.

In the embodiment of Figure 10, the cutting edge 1b of the knife has the shape of a triangular eccentric arc.

This arc has the property of having a center as in the case of a circular arc, all the diameters passing through this center being equal.

The shape of this sharp edge 1b has a relatively small radius of curvature at the top of the arc which is perfectly suitable for shaving parts of the face which are difficult to access or for precise stops around the legs of the beard and the mustache, while the relatively large radius of curvature on the sides of the arch is well suited for shaving the cheeks.

Knives having this shape can be sharpened by grinding these knives stacked on top of each other, as in the case of the method described above, but by using a machine for grinding polygonal shafts which is very widespread in the automotive industry.

Of course, the invention is not limited to the means for fixing and locking the knives to the support which has just been described. Thus, in the example of Figure 11, the knife 1c has at its ends bosses 5a, 5b directed towards the inside of the arc. In the space between these bosses 5a, 5b and the longitudinal grooves 21 and 22 of the support are forcibly engaged, that is to say by causing an elastic deformation of the knives, the sections 30a, 30b of complementary V section to that of gorges 21 and 22.

Profiles identical to profiles 30a, 30b are used to precisely position the knives 1c on a mandrel similar to that shown in Figures 1 to 3, replacing the pins 7, or the distance between the V grooves 3 and 4 of the mandrel could be identical to that separating the V-shapes of the sections 30a and 30b when the latter are assembled on the support.

The support 20, instead of having longitudinal grooves such as 21, 22, could include, in place of these, fixed ribs on which the knives 5,6 are positioned by snap-fastening. Similar means could be provided on the mandrel, so that the knives are positioned on the support in the same way as on the sharpening mandrel.

Of course, a single pin or profile could be provided on one side of the support, the other side of the knives being directly retained on the support without the interposition of a pin or similar means ensuring locking by elastic deformation of the knives.

Claims (9)

1. A blade unit for agrid-type shaver (31) having a support (20) receiving blades (1, 1b, 1c) and formed with slots (24, 27) perpendicular to its length, the blades (1) being located in such slots which keep the blades in spaced-apart parallel relationship aligned lengthwise of the support, the blades (1) being of arcuate shape and having some resilience and comprising securing means (5, 6; 5a, 6b) which co-operate with locking means (21, 22, 30, 30a, 30b) for assembling the blades on the support, characterized in that the blades (1) are formed near each end of the arc with a recess (5, 6) which opens towards the inside of the arc and the support (20) is formed with two longitudinal grooves (21, 22) parallel to support length, the recesses (5, 6) in the blades (1) being disposed opposite the grooves (21, 22), and the recesses (5, 6) are resiliently locked to two pins (30) engaged in the gap between the two grooves (21, 22) and the recesses (5, 6).

2. A blade unit according to claim 1, characterized in that the support (20) has a projecting central rib (23) which extends lengthwise of the support and whose end is formed with slots (24) receiving the blades (1).

3. A blade unit according to claim 2, characterized in that the support (20) also comprises two parallel flanks (26, 25) disposed in a plane perpendicular to the central rib (23) and formed with blade-receiving slots (27).

4. A blade unit according to claim 3, characterized in that the flanks (26, 25) bound the longitudinal grooves (21, 22) which receive the pins (30).

5. A blade unit according to any of claims 1 - 4, characterized in that the cutting edge (1a) of the blades is in the shape of a circle arc.

6. A blade unit according to any of claims 1 - 4, characterized in that the cutting edge (1b) of the blades is in the form of a triangular eccentric arc.

7. A blade unit according to any of claims 1 - 6, characterised in that the blades are embodied by a curved strip whose deformation is substantially constant along its curvature.

8. A process for sharpening the razor blades forming part of the blade unit according to any of claims 1 - 7, characterised in that the blades (1, 1b, 1c) are placed on a mandrel (2) formed with two longitudinal parallel grooves (3,4) spaced apart from one another by a distance equal to the distance between the two grooves (21, 22) in the support (20), the recesses (5, 6) or protuberances (5a, 6b) of the blades being positioned opposite the grooves (3, 4), two pins (7) or section members of appropriate cross-section are forcibly engaged in the gaps between each groove (3, 4) of the mandrel and the adjacent recesses (5, 6) or protuberances (5a, 6b) of the blades, the blades (1,1b, 1c) are clamped together, the mandrel (2) is rotated around its axis (X - X') and a grinding wheel (18) is applied to the outside surface of the blades stacked and clamped on the mandrel (2) so as to sharpen all the blades.

9. A process for assembling blades sharpened by the process according to claim 8 on the support (20) of the blade unit, characterized in that the sharpened blades (1, 1b, 1c) are removed from the mandrel (2) by removing the pins (7) or section members, the blades are placed on the support (20) in the same order in which they were placed on the sharpening mandrel (2) and the two pins (30) or the two section members (30a, 30b) are forcibly engaged in the gap between each groove (21, 22) of the support (20) and the adjacent recesses (5, 6) or protuberances (5a, 6b) of the blades.

Images