EP0652084B1 - Apparatus for cutting hair with a toothed cutter and process for manufacturing a cutter for such an apparatus - Google Patents

Description

The invention relates to a device for cutting hair with a tooth cutting device that has a stationary knife with at least one row of cutting teeth and a back and forth drivable knife with at least a series of cutting teeth, the cutting teeth having treads and the two knives at least with a part of the running surfaces of their cutting teeth abut each other and wherein the cutting teeth of at least one of the two Knives rounded at their free ends except in the area of their treads are trained.

The invention further relates to a method for producing a Knife for a device according to the type mentioned in the first paragraph above.

A device according to the type mentioned in the first paragraph above is known for example from DE 28 09 345 A1. In this known device is a thinning hair clipper for thinning, i.e. for thinning of hair when cutting hair. In this known device, the Cutting teeth of the reciprocable knife at their free ends with Rounding and smoothing. Behind the rounding down to the tooth root area but the cutting teeth of the reciprocable drive point into it Knife in the area of their side facing away from the running surfaces of the cutting teeth sharp edges as used in the manufacture of this knife Stamping process result. Due to these sharp edges, it can move along the Cutting teeth come across the skin to scratch the skin and irritate the skin, what is perceived by a user of the device as unpleasant and annoying and is therefore undesirable and disadvantageous.

The invention has for its object the above To avoid difficulties and a device for cutting hair according to the im train the first paragraph of the genus such that when moving along the Tooth cutting device of the device over the skin no scratching of the skin and no Irritation of the skin takes place. According to the invention, this object is achieved in that the cutting teeth of the at least one knife, which at their free ends except in Area of their treads has rounded cutting teeth, in addition also over their entire tooth depth down to the tooth root area except in Area of their treads are completely rounded.

In this way it is achieved in a very simple way that the cutting teeth of the device according to the invention except in the area of their treads, where the There are no sharp edges at all on the cutting edges of the cutting teeth are because the rounded cutting teeth except in the area of their Treads, from the free ends down to the tooth root area are rounded. This causes scratching of the skin and irritation of the skin with the perfectly rounded cutting teeth of the Tooth cutting device not possible, so that always a gentle cutting behavior an inventive device for cutting hair is achieved.

In a device according to the invention, in which due to its constructive training only one of the two knives in contact with the skin can come, it is sufficient to use only this knife with the invention completely to form rounded cutting teeth. But it is very often the case that both knives of a tooth cutting device can come into contact with the skin. In In this context, it has therefore proven to be advantageous if the Cutting teeth of both knives over their entire tooth depth down to the tooth root area are completely rounded except in the area of their treads. This ensures that neither of the two knives has a disruptive effect the skin can be exercised.

The manufacture of a knife according to the invention is perfect rounded cutting teeth can, for example, in one Metal casting process has taken place. Such a knife can also be produced in this way that a knife blank is first produced in one punching process, after which the perfectly rounded cutting teeth, for example, in one Etching process or have been produced by laser processing. As special It has proven to be advantageous if the two knives are formed by stamped metal parts and the rounding of the cutting teeth were produced in one stamping process are.

Knives of this type are particularly inexpensive because they have one simple stamping process and an equally simple subsequent stamping process are producible.

A method for producing a knife for an inventive Device for cutting hair is characterized according to the invention in that an unhardened steel strip with a specified strip thickness gradually into one Subsequent step tool device is transported and that at a first The next step is pre-stamping the steel strip to produce pre-stamped first Cutting tooth blanks of a knife takes place, the pre-embossed first cutting tooth blanks over a steel band bridge embossed during pre-stamping with one in relation remain connected to the band thickness of the lower bridge thickness, and after that at a second subsequent step in a cutting process the pre-embossed first Steel belt bridge connecting cutting tooth blanks is cut away and here at the same time, from the first cutting tooth blanks, second cutting tooth blanks of a knife be cut out and that after that in a third step Finish embossing the second cutting tooth blanks to produce finished embossed third ones Cutting tooth blanks of a knife takes place, with this finish stamping the third Cutting tooth blanks from their free ends over their entire tooth depth to the Tooth root area into except for the formation of the tread of the cutting teeth intended area are completely rounded embossed. By pre-stamping The first cutting tooth blanks is achieved using a relatively thick steel band a band thickness of, for example, 1.0 mm knife with cutting teeth with a Cutting tooth width of, for example, only 0.4 mm can be produced. By the Pre-stamp the first cutting tooth blanks and finish stamp the second Cutting tooth blanks for generating the third cutting tooth blanks is achieved that the from the free tooth ends to the tooth root area rounded shape of the cutting teeth in a very simple and inexpensive way in one Embossing process is made.

In such a method according to the invention has proven to be advantageous proven if a steel belt bridge is included in the first subsequent step during pre-stamping a bridge thickness that is at most 75% of the strip thickness is embossed. This is favorable with regard to a good cutting out of the second cutting tooth blanks.

It has proven to be particularly advantageous if during pre-embossing the first subsequent step, a steel belt bridge with a bridge thickness of at most 30% of the strip thickness is embossed. This is in view of a particularly good one Cutting out the second cutting tooth blanks and making them special fine cutting teeth advantageous.

It has also proven to be advantageous if after the third Follow-up step in the follow-up step tool device of the knife blank obtained here together with its third cutting tooth blanks hardened in a further working step becomes.

In this way, particularly hard knives with very hard and wear-resistant cutting edges achievable. By hardening the elastic limit is reached of the knife material increases, causing undesirable plastic deformation of the Knives are prevented.

Furthermore, it has proven to be very advantageous if another Another step is the third cutting tooth blanks of a knife in the Formation of the treads of the cutting teeth provided area for formation defined treads and sharp cutting edges. Such one Grinding the treads is particularly inexpensive. The treads can also be lapped.

The invention is described below with reference to one in the drawings illustrated embodiment described in detail, but not to the invention should be limited. 1 shows an oblique view of a razor according to one Embodiment of the invention, a short hair trimmer and a Has long hair cutting device. The Fig.2 shows schematically one Long hair cutting device, as provided in the device according to Fig.1 and the as a tooth cutting device with a back and forth driven tooth knife and with a toothed knife that is stationary relative to the reciprocable tooth knife Dental knife is formed. The Figure 3 shows a plan view in a compared to the natural size larger scale a practical variant of a stationary tooth knife of a tooth cutting device according to Fig. 2. The Fig.4 shows in a section along the line IV-IV of Figure 3 the stationary tooth knife according to Fig. 3. 5 shows a much larger one than FIGS. 3 and 4 Scale in oblique view of a single cutting tooth of the stationary tooth knife according to Figures 3 and 4. In Figures 6 to 13 are corresponding to a section according to the line XIII-XIII in Figure 3 which in an inventive method for Manufacture a tooth knife according to Figures 3 and 4 step by step successively obtained products and partly those for producing them Products required tools of a subsequent step tool device schematically shown.

FIG. 1 shows a shaving device 1 for cutting hair. The Shaving device 1 has a housing 2 on which a shaving head 3 sits. The shaving head 3 comprises a shaving head frame 4 in which a short hair cutting device 5 for Cutting whiskers is provided. The short hair cutter 5 consists in essentially from a curved sieve shear film 6 and not in Fig.1 visible, in the curvature of the screen shear 6 resiliently pressed lamellar knife. Furthermore, the shaving device 1 has a long-hair cutting device for cutting long whiskers and scalp hair a tooth cutting device 7. The tooth cutting device 7 is in the region of a side wall 8 of the housing 2 in the longitudinal direction the shaver 1 slidably held back and forth between one in Fig.1 shown rest position and a not shown in Fig.1, closer to the Short hair cutter 5 lying operating position can be moved. The shaving device 1 has a for moving the tooth cutting device 7 Slide 9 on.

FIG. 2 shows the tooth cutting device 7 in a schematic manner of the shaver 1 according to Fig.1. The tooth cutting device 7 has a stationary one first knife 10, which as a tooth knife with a row of cutting teeth 11 is formed and that on a carrier, not shown, for the entire Tooth cutting device 7 is held stationary. Furthermore, the Tooth cutting device 7 has a second knife 12 which can be driven back and forth, which is also designed as a tooth knife with a row of cutting teeth 13 and back and forth parallel to a drive direction indicated by an arrow 14 can be driven here. The cutting teeth 11 of the stationary tooth knife 10 have treads 15, and the cutting teeth 13 of the back and forth drivable tooth knife 12 have running surfaces 16. The two knives 10 and 12 are at least with a portion of the treads 15 and 16 of their cutting teeth 11 and 13 to each other. The stationary tooth knife 10 and the back and forth hereby driven tooth knife 12 parallel to one by a further arrow 17th indicated direction of pressure with the running surfaces 15 and 16 of their cutting teeth 11 and 13 held pressed together. The back and forth drivable Toothed knife 12 is carried by a knife holder 18 on which a compression spring 19 attacks, which is on a stationary counter bearing 20 on the carrier for the entire Tooth cutting device 7 supports. The tooth pitches of the two rows of Cutting teeth 11 and 13 of the tooth knives 10 and 12 are different.

For driving the tooth knife 12 which can be driven back and forth a back and forth drivable drive part 21 is provided, for example is formed by a pivoted drive lever. Between the drive part 21 and the reciprocable tooth knife 12 or that A joint device 22 is provided for the tooth holder 12 carrying the knife holder 18, via the one driving force from the drive part 21 to the back and forth drivable Toothed knife 12, essentially in the area of the point of attack Resulting of the frictional forces between the two knives 10 and 12, is transferable. The joint device 22 has two inclined in opposite directions to the pressing direction 17 extending webs 23 and 24, which with the drive part 21 via a joint 25th or 26 and are connected to the knife carrier 18 via a respective joint 27 or 28.

The drive part 21 and the webs 23 and 24 and the knife carrier 18 are formed in one piece from plastic, the joints 25, 26, 27 and 28 through Film hinges are formed. A practical embodiment variant is shown in FIGS. 3 and 4 of a stationary tooth knife 10. As from Figures 3 and 4 can be seen, this stationary tooth knife 10 is both in the range of the Cutting teeth 11, approximately in the tooth root region 29, as well as in that of the Row of the cutting teeth 11 facing area 3 cranked.

In the stationary tooth knife 10 according to FIGS. 3 and 4, one Tooth cutting device 7 according to Figure 2 are - as shown in Figure 5 in detail is - the cutting teeth 11 at their free ends 31 except in the area of their running surfaces 15 rounded. In addition, the cutting teeth 11 are now also over their entire tooth depth into the tooth root area 29 except in Area of their treads 15 completely rounded. This means with in other words, the cutting teeth 11 first along Curvature lines are rounded, which are parallel to the treads 15 of the Cutting teeth 11 planes lie, as indicated in Figure 5 with the radius r1 and that the cutting teeth 11 secondly along lines of curvature are rounded, in perpendicular to the treads 15 and at the same time are parallel to the plane of the teeth, as shown in Fig.5 with the Radius r2 is indicated, and that the cutting teeth 11 third along Curvature lines are rounded, which are perpendicular to the running surfaces 15 and at the same time lie at right angles to the plane of the teeth, as shown in Fig. 5 is indicated with the radius r3.

Although this is shown in FIGS. 3, 4 and in particular 5 only for the Cutting teeth 11 of the stationary tooth knife 10 is shown, but is from Fig.2 it can be seen that the cutting teeth 13 of the reciprocable Tooth knife 12 one of its free ends over its entire tooth depth into the Tooth root area have a fully rounded design, this of course except in the area of the running surfaces 16 of the cutting teeth 13 of the reciprocating knife 12.

The two tooth knives 10 and 12 are particularly advantageous the tooth cutting device 7 is formed by stamped metal parts and are the roundings the cutting teeth 11 and 13 of the two tooth knives 10 and 12 in one stamping process been made.

Below is an advantageous method of making one Tooth knife for a tooth cutting device of a device for cutting hair, So for example for producing a stationary tooth knife 10 according to the Figures 3 and 4 described with reference to Figures 6 to 13.

6 shows an uncured steel strip 32 in a cross section shown, the transverse direction of which is indicated by an arrow 33 in FIG. The Steel strip 32 has a predetermined strip thickness D, which is for example 1.0 mm. A such unhardened steel strip 32 is gradually perpendicular to its transverse direction 33 transported to and in a subsequent step tool device Follow-up tool setup while performing step-by-step successive subsequent steps transported step by step.

In the case of a first one carried out in the subsequent step tool device The following step takes place - as is indicated schematically in FIG. 7 - in one Embossing device 34, which has a lower tool part 35 and an upper tool part 36 has a pre-stamping of the steel strip 32 to produce pre-stamped first Cutting tooth blanks 37 of a tooth knife, the pre-embossed first Cutting tooth blanks 37 with a steel band bridge 38 embossed during pre-stamping a smaller bridge thickness d in relation to the strip thickness D of the steel strip 32 stay connected. This pre-stamping process is shown schematically in FIG. The Intermediate 39 obtained in the pre-embossing process according to FIG. 7 is shown in FIG shown. As can be seen from FIGS. 7 and 8, the described Method for pre-stamping in the first subsequent step using a steel belt bridge 38 embossed a bridge thickness d, which is about 30% of the strip thickness D.

After pre-stamping in accordance with the first subsequent step, a second subsequent step with a cutting device 40, which consists of a cutting plate 41 and consists of a cutting punch 42 in a cutting process which the pre-embossed Cutting tooth blanks 37 connecting steel band bridge 38 are cut away and at the same time 37 second cutting tooth blank 43 from the first cutting tooth blanks 37 a knife cut out, as shown schematically in Fig.9. That at The intermediate 44 obtained in the second subsequent step according to FIG. 9 is shown in FIG shown.

After the second step in the step tool setup takes place in a third subsequent step in a further embossing device 45, the one Has lower tool part 46 and an upper tool part 47, a finish stamping of second cutting tooth blanks 43 for producing finished embossed third ones Cutting tooth blanks 48 of a knife. With this finish stamping according to the third Follow-up step in the follow-up step tool device become the third cutting tooth blanks 48 from their free ends over their entire tooth depth to the Tooth root area into except for the formation of the tread of the cutting teeth intended area 49 embossed completely rounded. It is simple through a correspondingly rounded design of the embossing zones in the Tool upper part 47 of the further embossing device 45 is reached. That with the Finishing embossing process according to FIG. 11 intermediate product obtained, that is to say the received product Knife blank 50 is shown in Fig.12.

The knife blank 50 shown in FIG another step including its third cutting tooth blanks 48 hardened what can be done using well known technologies.

The hardened knife blank 50 then becomes one not shown Grinding device supplied, in a further step, the third Cutting tooth blanks 48 of a knife in the to form the tread of the cutting teeth provided area for the formation of defined treads 15 and sharp Cutting edges 51 are ground. After this grinding process they are Receiving cutting teeth 11 of the tooth knife 10 produced, the total height H have that is slightly less than the original band thickness D of the steel band 32nd After the grinding process for grinding the treads 15, the method for Production of the tooth knife 10 essentially ended. Instead of one Grinding process can also be used to produce the defined running surfaces 15 Lapping process are used.

With a tooth cutting device with completely rounded trained cutting teeth, as described with reference to the above Exemplary embodiment is explained, is achieved in a very simple manner that in the Cutting teeth - apart from their sharp cutting edges - no sharp teeth at all Edges are present so that when a tooth cutting device is moved along with Tooth knives with such perfectly rounded cutting teeth the skin is unable to scratch, hurt or irritate the skin. To this In this way, a gentle cutting behavior is always guaranteed.

A method of making dental knives with perfect rounded cutting teeth, as explained above, offers the essential advantage that the completely rounded design of the cutting teeth in a particularly simple way by pre-embossing and one after another performed cutting process is carried out finish stamping of the cutting teeth. Through an embossing process, such completely rounded cutting teeth are formed can be produced in a particularly simple manner. Furthermore, such an embossing process therefore particularly advantageous because with such an embossing process in a relative large angle range lying cutting angle in the area of the cutting edges of the Cutting teeth are realizable.

The invention is not based on the above Embodiment limited. According to the described embodiment is the device for cutting hair by a razor with a Tooth cutting device formed. The measures according to the invention are also included in the other devices for cutting hair can be used advantageously, for example in so-called hair trimmers or beard trimmers, the one have essentially elongated rod-shaped housing, at least in A tooth cutting device is provided in the head region of the housing. For example such devices are disclosed in EP-A1-0 325 326 and US-A-5 054 199.

Claims (8)

1. An apparatus (1) for cutting hair, having a toothed cutting device (7) comprising a stationary cutter (10) with at least one row of cutter teeth (11) and a reciprocatingly drivable cutter (12) with at least one row of cutter teeth (13), the cutter teeth (13) having shearing faces (15, 16) and the two cutters (10, 12) being in engagement with one another by at least a part of the shearing faces (15, 16) of their cutter teeth (11, 13), and the cutter teeth (11, 13) of at least one of the two cutters (10, 12) being rounded at their distal ends (31) except for the area of their shearing faces (15, 16), characterized in that the cutter teeth (11, 13) of at least one cutter (10, 12) having cutter teeth which are rounded at their distal ends (31) except for the area of their shearing faces (15, 16) are in addition wholly rounded over their entire tooth depth into the proximal tooth areas (29) except for the area of their shearing faces (15, 16).
2. An apparatus as claimed in Claim 1, characterized in that the cutter teeth (11, 13) of both cutters (10, 12) are wholly rounded over their entire tooth depth into the proximal tooth areas (29) except for the area of their shearing faces (15, 16).
3. An apparatus as claimed in Claim 1 or 2, characterized in that both cutters (10, 12) are formed by punched metal parts and the cutter teeth (11, 13) are rounded in an embossing process.
4. A method of manufacturing a cutter for a toothed cutting device of an apparatus as claimed in any one of the Claims 1 to 3, characterized in that an unhardened steel strip (32) having a given strip thickness (D) is moved stepwise to a follow-on tool arrangement and in that in a first follow-on step the steel strip (32) is pre-embossed to form pre-embossed first cutter-tooth blanks (37) of a cutter, which pre-embossed first cutter-tooth blanks (37) remain connected to one another by steel-strip bridges (8) formed during pre-embossing and having a small bridge thickness (d) in relation to the strip thickness (D), and in that subsequently in a second follow-on step the strip-steel bridge (8) connecting the pre-embossed first cutter-tooth blanks (37) is cut away in a cutting operation and at the same time second cutter-tooth blanks (43) of a cutter are formed from the first cutter-tooth blanks (37), and in that subsequently in a third follow-on step the second cutter-tooth blanks (43) are post-embossed to produce post-embossed third cutter-tooth blanks of a cutter, during which post-embossing the third cutter-tooth blanks (48) are embossed so as to be wholly rounded over their entire tooth depth from their distal ends (31) into the proximal tooth areas (29) except for the areas intended for the formation of the shearing faces (15, 16) of the cutter teeth (11, 12).
5. A method as claimed in Claim 4, characterized in that a steel-strip bridge having a bridge thickness (d) equal to at the most 75 % of the strip thickness (D) is formed during pre-embossing in the first follow-on step.
6. A method as claimed in Claim 5, characterized in that a steel-strip bridge having a bridge thickness (d) equal to at the most 30 % of the strip thickness (D) is formed during pre-embossing in the first follow-on step.
7. A method as claimed in Claim 4, 5 or 6, characterized in that after the third follow-on step in the follow-on tool arrangement the resulting cutter blank including its third cutter-tooth blanks (48) is hardened in a further process step.
8. A method as claimed in Claim 4, 5, 6 or 7, characterized in that the third cutter-tooth blanks (48) of a cutter are ground to form well-defined shearing faces (15, 16) and sharp cutting edges in the area intended for the formation of the shearing faces (15, 16) of the cutter teeth (11, 13).

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