CA1172839A - Shaving instrument - Google Patents

Abstract

A B S T R A C T

A shaving instrument having a base part of plastics material, at least one razor blade with a cutting edge upon this base part, a cover part fixed to the base part in such a way that the razor blade is firmly clamped be-tween the base part and the cover part, and the cover part has a glide surface which faces the skin to be shaven and away from the base part, and ends at a distance from the cutting edge of the razor blade, a guard bar which comes into contact with the skin and extends at a distance and parallel to the cutting edge of the razor blade, having at its ends legs at an angle that are connected without play to either one of the base part and the cover part.

Description

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,, . -'~ SHAVING INSTRU~NT
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The invention relates to a shaving instrument havingat least one razor blade which is firmly clamped between a base part made of plastics material and a cover part pro-vided with a glide surface which faces the skin to be sha-ven and ends at a predetermined distance from the cutting edge of the blade, and having a guard bar arranged in front of the blade cutting edge, the guard bar having a surface area which come~ into contact with -the skin and is equipped with elements for stretching the skin and is aligned at a predetermined distance parallel to the blade cut~ing edge.
~ he quality ol a ~having in~trument not only depend0 on the exact po~ition ol the blade cutting edge relative to the guard barf but al80 on the effectivene~s of the ele-ments on the guard bar which stretch the ~kin~ ~he~e ele-ments not only have the purpose of pre~enting skin crea~e~
from forming when the shaving instrument is gu~ded in an un-accustomed direction which may cause unexpected injuries, but al~v of lifting up the hair~ of the beard in front o~
the blade cutting edge 80 -that they can be cut clo9e to the root~ In the kno~ln instruments of the above-described .

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-type, the base part and -the guard bar consist of one piece and, for cost reasons, of plastics material. In these instruments, it is not possible to pro~ide the stretching elements wlth edges which are sufficiently sharp but not irritating to the skin, in . order thereby to achieve a satisfactory stretching effect, even .. if these stretching elements have a saw-tooth shaped cross-sec-tion, as -this has become known from West German Patent 1,110,047.
One aspect of the present invention is based on the novel finding that such stretching elements can be manufactured with sharp edges by plastic deformation with the displacement of por-`; tions of the surface area of the guard bar, when the material of the guard bar is metal. Therefore, the basic concept of this aspect of the invention is to manufacture the guard bar of metal ., and to combine it with one of the two parts clamping the razor blade~ As a result, it is possible to select not only the most suitable material for the parts clamping the blade and for the guard bar, but also the mo,st Eavorable manufacturing me-thod.
Broadly stated, there:Eo:re, according to this Eirst as~pect of the presen-t :invention, there is pro~ided a sha~iny instrument comprisiny a holding part o~ plastics rna.terial haviny a g].ide . surface facing the skin to be shaven and a guard bar of metal cominy into contact with the skin, said guard bar connected to ` said holding part, said guard bar provided with a plurality of - elements with sharp edges for stretching the skin, Another aspect of the present invention is the manner in which the correct spacing between the blade cuttiny edge and the guard is achieved.

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Accoxding to this other aspect~ the~e is provided a shaving instrument eomprising a base part of plaskics material, at least one razor blade having a cutting edge placed on said base part, a cover part a-ttaehed to said base part so that said razor blade is clamped between said base part and said cover part, said cover part having a glide surface facing the skin to be shaven and away from said base part and endiny at a distance from said cutting edge of said razor blade, a guard bar for contacting the skin ahead o~ said razor blade, the guard ~ar having a main portion and legs at each end ar~anged at an angle to said main portion and connected without play to one of said base part and said cover part, at least two lugs connected to one of said base part and said cover part near said legs of said guard bar, said lugs engaging the main portion of said guard bar and thereby maintaining the main portion of said guard bar positioned at a predetermined distance from and parallel to said cuttlng edge of said razor blade.
Because the luys ]~eeping the guarcl bar spaced away are located outside of the efeective rancle o~ the eutting edge, unim~
paired passaye oE cut hairs and soap throucJh the opening between the guard bar and -the blade is achieved.
Other features of -the invention will become clear ~rom the following detailed diseussion of the invention with reference to the aceompanyîng drawings, in whieh:
Figure 1 is a side view of a shaving instrument aeeording to the invention;

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-3a-Figure 2 is a top view of the instrument of Fiyure 1;
Figure 3 is a section along the line III~ of Figure 2;
.: Figures 4 to 7 show stages of the manuEacture of the . teeth on the guard bar in sectional and top view, the sections of Figures 4 and 6 being taken along the lines IV-IV of Figure 5 and VI-VI of Figure 7, respectively;
Figure 8 is a bottom view of the instrument; and . Figure 9 shows a detail on a larger scale.
.~ The instrument in accordance with the invention has a blade holder which in its totality is denoted by reference .:', ~3 3 ~

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numeral 4 and i9 compoeed of a ba~e part 1 with a handle mDlded to the base pa~ 1 in one plece a~d a cDver 3, The ra~r blade 5 iB firmly clamped between ~ase p~rt 1 and co-ver ~ and cannot be exchanged, ~or protection~ B guard bar 6 is provided which i B ~upported by the base part ~, ~he front sidesof the base part 1 and the cover 3 form a front face 7 which, together with a glide surface 8 of the cover 3, forms a fron~ edge 9.

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~ he blade 5 protrudes beyond the front face 7. ~he guard bar 6 has at its end~ leg6 10 which form an angle with the guard bar 6 and are inserted into recesses of the base part and are maintained in fixed position ~n these recesses without play. ~or exactly maintaining the distance of the guard bar 6 from the front face 7, lug~ 1a are provi~e~ at the base part 1 in close proximity to the legs. The guard bar iB inserted into the ~lade holder 4 in 6uch a way that its leg~ e~tend parallel to the center plane 28 of the blade 5, and it~ ~urface area coming ~nto contact with the skin e~tends parallel to the cutting edge 26 o~ the blade, In the illustrated example, the guard bar 6 has four rows of teeth provided on stretching elements arranged sym-metrically to -the center plane 11 of the guard bar and the legs 10, However, the rows of teeth 12,13,14,15 do not al-, ways have to be arranged symmetrically, and, further~ the number of ',`.,~,.~
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row~ of teeth may deviate ~rom the n~mber four, Although the rows oI teeth 14 and 15 are of les~ importance for the ~ha~ing action of the inetrument, it is u~eful to arrange the~e row8 of teeth because they ma~e it pos6ible that the guard bar 6 can be inserted in the base part 1 without ha~ing to checX whe~her the rows of teeth are in fact located on the ~ide facing the blade 5~ ~he teeth are formed by coining and have eharp edges 169 17, 18, 19 which e~tend parallel to the a~is of the guard bar.
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The positions of the rows of teeth are selected in ~uch : a way that at least one of them is located on that ~urface portion o~ the guard bar 6 which faces the blade. Thi~ por-tion i~ defined by a line 25a with which a tangential plane 24a e~tending through the blade cutting edge 26 contacts the surface of the ~uard bar 6. An improved embodiment re~ult~
in that another row of teeth iB arranged in front o~ thi~
line of contact at the guard bar 6.

~he manu~acture o~ the teeth iB illu~trated in ~ig~. 4 to 7~ The guard bar 6 iB placed on a ~upport ~0 in ~uch a way that the center plane 1 include~ an angle of approxima-tely 30 ~ith the direction of movement of the toDl 21, The tool 21 includes punches 22 which are arranged in two row~
. an~ coin a pluralit~ of ~ymmetrically arranged teeth 13, 15 on the guard bar 6~ Subsequentl~a the guard bar 6 i~ turned, ~: - 6 - ~ ~ 7~3(3 ' ~o that its center plane 11 again includes an a~gle of 30 with the direction ~f movement of the tool, howevery the incli~ation be~ng oppDsite as compared to the ~irs~ coining prDcedure. Simultaneously, the guard bar 6 has been moved a~ially, ~o that the teeth 12, 14 produced by the tool are off~et relative to the teeth 1~, 15 of the previously formed row of teeth, ~ he punches 22 do not have to be pri~matic and they do not have to have the end face 23 perpendicular to the moving direction of the tool 21. The tool as illustrated forms teeth whose sharp edges extend parallel to the rows of teeth.
Each tooth projeets over its entire length uniformly above the ~urface of the guard bar 6, A tangential plane of the guard bar 6 extending through the front edge 9 eontacts the guard bar along the line of contact 25. ~he cutting edge 26 of the blade 5 is to have a certai~ position relative to the tangential plane 24. ~he cutting edge ma~ pro~ect by up to 0,12 mm over the tangential pl~ne 24 or recede by up -to OaO~
mm Iro~ it. The glide ~urface 8 i8 pre~erably loca~ed ~n the .tangential plane 24. ~he sharp edges 16 7 17 of the rows of teeth arranged in front of and behind the line of contact 25 should preferably be located in the tangential plane ~4.
~inally, for achieving the object of the invention9 the di~-tance of the guard bar 6 from the cutting edge 26 and from the front face 7 also ~ys a role. Useful re~ult~ are ob-- i .
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3 S~i tained w~en the dis~ance between the ~l~e of c~ntact 25 from the blade cutt~ng ed~e i~ between 1~0 and ~ or example~ 1.2 to 1,6 mm, Go~d sh2ving re~ults could be achieved ~ith instru-ments ~hich are described in further detail bel~w.

The guard bar 6 had a circular cross-section with a diameter of 1r2 to 272 mmO ~he guard baT wa~ provided with .~our rcws of teeth arra~ged ~ymmetrically to the cen-ter plane 11~ ~he sharp edges of the teeth e~tended paral-lel to the row~ of teeth and the la~ter extended parallel to the longitudinal a~is of the guard bar and9 thus, also to the cutting edge 26 of the blade. ~he lengths of the sharp edges of the teeth ~aried between 0,3 and 1.0 mm.
They each pro~ected.b~ their entire lengths above the sur-face of the guard bar, thi.s dis~ance measuring between 0.~
and 0~12 m~0 ~he ~ooth cpaces within o~e row were of a ~lze of a~out 1.0 mm, The teeth of adjacent r~w~ were of~eet.
The distance between the r~Js i~ ~elected between 0.5 and 1.5 mm. ~specially favorable ~e~ults were obtained with distances which measured between 0.7 an~ 1.0 mm~ The cen-ter plane 28 defined by the sides 27 which form the cutting edge 26 of the razor blade 5 and the tangential plane 24 in-cluded an angle of between 14 and 28~

~ xcellent shaving results were obtained with the ~ol~
lowing instrument~ The guard bar 6 had a diameter of 1.59 + 0.01 mm and was provided with rows of teeth which had lengths of 36 mm and were composed of twenty-two teeth~
The length of the blade cutting edge was 37 mmO The length of the individual sharp edges of the teeth was 0.5 mm, The teeth had within each row a spacing of 1.0 mm, Pits in the surface of the guard bar, constituting tooth roots 6a have a spacing of about 1 mm between the rows of the teeth 12 and 14 as well as between -the rows 13 and 15~ lhe four rows of teeth provided were staggered approximately 30 on the circumference of the guard bar and were arranged sym-metrically to the center plane 11 of the latter. The sharp edges of the teeth protruded uniformly about 0.07 mm from the surface of the guard bar. The center plane 28 of the blade cutting edge 26 and the tangential plane 24 included an angle of 20, ~y the selection of the adequate manu~
facturing tolerancea, it was achieved that -the blade cut-ting edge 26 projected above the tangential plane 24 by only 0.05 to OJ 09 mm~ The sharp edges 16 of the teeth 12 were located in the tangential plane 24~ ~he distance of the line of contact 25 a from the cutting edge 26 was 1,4 mm~

~ he arrangement and the dimensions were selected in such a way that the loads occurring during the normal use . .

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an~ life span Or ^the lnstr~nent di~ ~t cau~e any di~place-ment or permanent deformation ~f the lndi~i~ual part~
~providi~g an approprla~ely ~tlff constructi~n~ i~ was po~-sible to ensure that9 prior to, ~uring and after the use of ~he in6trument, the front edge 9, the cutting edge 26 ana the lines of contact 25, 25a were locate~ between two ima-inary parallel planes having a distance from one another of at most 0,05 mm~ preferably 0~0~ mm, -' .
~ ig. 9 shows an embodiment of the shaving in~trumerlt by way of example on a larger scale~ The base part 1 has a lug 1a near each en~ of the cutting edge 26 for the guard bar 6 and alBo 8 lug 1b for the cutting edge 26 of the blade 5.
~he blade 5 has holes 29 which are in al-lgnment with bores in the base part when the ~lade ie in the correct position, ., .
The bores are ~maller than the holes 29 and po~ltioned in exact distance f~om the lug~ 1a~ The cover part '3 hae ri-vet plne which extend without corltact through the holes 29 of the blade and flt snugl~ in the bore~ of the ba~e part 1.
Af ter the blade ha~ been moved ~orwardly by means of a mag-net and the cutting edge 26 rests against the lugs 1b, riveting is performed and the blade 5 is thereby permanently clamped be-t~een the base part and the cover ~lith the cutting edge at the exact distance from the guard bar 6 andl due to the expan-sion of the rivet pins in the bores of the base part, the "j . .
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~7~3 t cover iB e~actly po~itioned a~ well, Due tD the fact th the lug~ ~a ~nd 1b are prDYided on the same part ~f the bla~e holder, this distance between the guard bar and the bla~e cutting ed~e can be hel~ within very ~mall tolerances.

Another ~ay of en~uring this distance between the cut-ting eage a~d the guard bar 6 without using the lug~ 1b ~e-~ides in manufacturing the holes 29 of the blade e~actl~ ln relation to its cutting edge ~6, In this case, the riYet pin~ 30 are utilized for the e~act positloning ~f the cut-ting e~ge 26. ~he diame~er of the ri~et pins i8 smaller than that of the holes 29 in the blade, however, the pins are provided with two oppositely loczted ribs ~1 which are arranged in the direction perpendicular to the cutting edge 26 ~he cylindrical generated surIace circumscribing these rib~ 31 ~as a diame*er w~ich læ approximately 0.01 mm smal-ler than that of the blade hole 29~ ~he diameter~ ~ the bore~ ln the base part 1 can be equal ~o or be omaller b~
up to 0,02 mm than the d~ameter~ of the hole~ 29, Instead of the two ribs as illustrated, it i5 also possible, e~g, t to provide three ribs distri.buted uniformly over the circum-ference, A centering procedure results from a minute expan-sion of the pins during the riveting operation, so that the holes in the blade are in e~act alignment with the bores in the base part 1 Of course9 the lugs 1b are omitted in these cases~

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It i~ essential that the alignment of the guard bar 6 relative to the cutting edge 26 is effec-ted by means which are provided together on one of the two part~ of the blade holder, either on the base part 1 or the cover part ~, In order to ensure that the lugs 1a are not deformed by excessive resistance when the legs of the guard bar are in~erted into the blade holder, the legs of the guard bar 6 are calibrated in order to reduce the tolerance. This permits to fit the legs into the recesses provided in the base part 1 for their reception and to maintain them there without play in fixed position. These recesses which are - not illustrated in the drawing are arranged in the blade holder and are provided with two spacedly arranged wall surfaces extending parallel to the plane 11 of the guard bar~ The legs 10 of the guard bar 6 are calibrated paral-lel -to the same plane to a dimension which i~ appro~imately 0002 mm smal]er tharl the ~mallest dimension oi' the lege permissible wlth respect to tolerance prlor to calibrationu ~ he invention is not limited to the embodiment illu~-trated in the drawing.
In the embodiment, a wire of s-tainless steel was used for the guard bar 6, however, other metallic materials c~
be used. The shape of the teeth and the rows of the teeth may vary. The cross-section of the guard bar 6 may deviate from the circle shape. However, it is useful to construct '~' . ~,.

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co~ve~l~ the ~urface area coming into contact wi~h the ~kin, ~ he handle of the ~nstrument i8 formed in one piece with the blade holder or i~ connected to the lat-ter, ~ow-ever, a construction may al~o be selected whereln a loo~ely in~ertable blade i~ clamped in the blade holder in the ~nown manner, ~ . However, the instrument can also be use~ withcut a blade .! either for massaging the facial skin or for adjusting the .~ hair~ of the beard prior to ~ha~ingO
In order to ensure the e~act position of the lugs 1a, 1b or of the lug~ 1a and the bores in the base part for the rivet pin~ during the production, it i8 advantageous to u~e an in~ection molding tool for the manu~acture of a blade ~ol-. der which includes the negativee of all lug8 or bores i~ a part of the tool which i~ con~-tructed in one piece or i~ GOm-posed of a plurallty of element~ which remain fixedly con-nected to one another even when the tool iB opened, . i,, . ~ :, .... .

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Claims (31)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A shaving instrument comprising a base part of plastics material, at least one razor blade having a cutting edge placed on said base part, a cover part attached to said base part so that said razor blade is clamped between said base part and said cover part; said cover part having a glide surface facing the skin to be shaven and away from said base part and ending at a distance from said cutting edge of said razor blade, a guard bar for contacting the skin ahead of said razor blade, the guard bar having a main portion and legs at each end arranged at an angle to said main portion and connected without play to one of said base part and said cover part, at least two lugs connected to one of said base part and said cover part near said legs of said guard bar, said lugs engaging the main portion of said guard bar and thereby maintaining the main portion of said guard bar positioned at a predetermined distance from and parallel to said cutting edge of said razor blade.

2. The shaving instrument according to claim 1, wherein the guard bar is formed by metal wire and is provided with a plurality of elements with sharp edges for stretching the skin acting in the same direction as said cutting edge of said razor blade.

3. The shaving instrument according to claim 2, wherein said wire forming said guard bar is of a malleable material, said stretching elements formed by plastic deformation and displacement of portions of the surface area of said guard bar.

4. The shaving instrument according to claim 1 or 2, comprising a plurality of additional lugs connected to one of said base part and said cover part near the ends of said cutting edge, said additional lugs serving for maintaining the exact position of the razor blade.

5. The shaving instrument according to claim 2, wherein said guard bar is composed of a calibrated wire whose nominal diameter ranges from between 1.2 and 2.2 mm.

6. The shaving instrument according to claim 5, wherein said base part defines recesses opening toward said guard bar, said recesses receiving without play said legs of said guard bar, said recesses each having two wall surfaces arranged at a distance from one another and ex-tending parallel to said cutting edge of said razor blade, and wherein said legs of said guard bar have plane sur-faces produced by pressing and extending parallel to the center plane of said guard bar, said surfaces of said legs having a distance from one another which is approximately 0.02 mm smaller than the smallest wire diameter admissible with respect to tolerance.

7 . The shaving instrument according to claim 2, wherein said cover part includes a front edge arranged parallel to and spaced away from said cutting edge of said razor blade, and wherein the location of said cutting edge of said razor blade ranges from a point 0.12 mm in front of to a point 0.03 mm behind a tangential plane of said guard bar extending through said front edge.

8 . The shaving instrument according to claim 7, wherein said cutting edge of said razor blade is formed by sides of said razor blade converging toward one another, said sides defining a center plane which includes an angle of 14 to 28° with said tangential plane of said guard bar extending through said front edge, and wherein said glide surface of said cover part facing away from said blade is situated in said tangential plane, the width of said glide surface being greater than the distance of said front edge from said cutting edge of said razor blade.

9. The shaving instrument according to claim 8, wherein said center plane and said tangential plane include an angle of 18 to 24°.

10. The shaving instrument according to claim 7, wherein the distance be-tween said cutting edge of said razor blade and the line of contact of said tangential plane with said guard bar is 1.0 to 1.8 mm.

11. The shaving instrument according to claim 10, wherein the distance be-tween said cutting edge of said razor blade and said line of contact is 1.2 to 1.6 mm.

12. A shaving instrument comprising a holding part of plastics material having a glide surface facing the skin to be shaven and a guard bar of metal com-ing into contact with the skin, said guard bar connected to said holding part, said guard bar provided with a plurality of elements with sharp edges for stretching the skin.

13. The shaving instrument according to claim 12, wherein said guard bar is of a malleable wire material, said stretching elements formed by plastic de-formation and displacement of portions of the surface area of said guard bar.

14. The shaving instrument according to claim 12, wherein said guard bar is composed of a calibrated wire whose nominal diameter ranges from between 1.2 and 2.2 mm.

15. The shaving instrument according to claim 12, wherein said stretching elements are arranged on said guard bar in at least two rows extending parallel to the axis of said guard bar, said stretching elements offset from row to row in the axial direction of said guard bar.

16. The shaving instrument according to claim 15, wherein said rows are spaced from one another by 0.5 to 1.5 mm.

17. The shaving instrument according to claim 15, wherein said rows are spaced from one another by 0.7 to 1.0 mm.

18. The shaving instrument according to claim 2, wherein said stretching elements have file-like or rasp-like teeth with sharp edges, said sharp edges acting in the same direction as said cutting edge of said razor blade.

19. The shaving instrument according to claim 18, wherein at least one of said rows of stretching elements with said teeth is arranged in a surface area of said guard bar facing said razor blade, said surface area defined by a line of contact of a tangential plane of said guard bar extending through said cutt-ing edge of said razor blade.

20. The shaving instrument according to claim 19, wherein at least one additional row of stretching elements with said teeth is arranged in the surface area outside said line of contact and facing away from said razor blade.

21. The shaving instrument according to claims 19 or 20, wherein said sharp edges of said teeth of said rows of stretching elements are located approximately in said tangential plane of said guard bar extending through said cutting edge of said razor blade.

22. The shaving instrument according to claim 12, wherein said stretching elements have file-like or rasp-like teeth with sharp edges.

23. The shaving instrument according to claim 18, wherein the sharp edges of said teeth of said rows of stretching elements are arranged symmetrically relative to a center plane defined by said legs arranged at an angle at the ends of said guard bar.

24. The shaving instrument according to claim 22, wherein tile sharp edges of said teeth of said rows of stretching elements are arranged symmetrically relative to a center plane defined by legs arranged at an angle at the ends of said guard bar.

25. The shaving instrument according to claims 18 or 22, wherein said sharp edges of said teeth have a distance from the surface of said guard bar of 0.03 to 0.12 mm.

26. The shaving instrument according to claims 18 or 22, wherein said sharp edges of said teeth have a length of 0.3 to 1.0 mm.

27. The shaving instrument according to claim 18, wherein the total length of the gaps between said teeth of each row of teeth is at least one-fourth of the overall length of said row.

28. The shaving instrument according to claim 27 wherein the gaps between said teeth have a length of about 1.0 mm.

29. The shaving instrument according to claim 18, wherein pits are pro-vided in the surface of said guard bar in front of each of said teeth, the front faces of said teeth extending directly into said pits and constituting one of the walls of said pits.

30. The shaving instrument according to claim 29 wherein the volume of each tooth projecting from the surface of said guard bar equals the volume of said pit located in front of said tooth.

31. The shaving instrument according to claims 18 or 22 wherein the sur-face area portion of said guard bar occupied by said stretching elements rela-tive to the surface area portion of said guard bar coming into contact with the skin is about 30%.