DE2629919A1 - METHOD OF MANUFACTURING SHEARS FOR DRY SHAVERS - Google Patents

Description

Patent attorneys

Light ■ Dr. Schmidt

Hansmann i-iarrmann

P.O. Box 7012 05

8000 Munich 70

June 30, 1976

THE GILLETTE COMPAlTI A Delaware Corporation Prudential Tower Building Boston, Massachusetts 02199 V. St. A.

"Process for making seer leaves for dry shavers "

The present invention relates to a method of making perforated sheet metal foils for dry razors.

The shaving head of a dry razor consists in a known manner of a fixed, outer, perforated one Blade and an inner, movable cutter that contacts the back of the blade. the Cutting device can either consist of a set of separate blades or it can be made of perforated sheet metal itself be made.

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The co-pending application dated June 29, 1976, Anw.Akte 12527 the applicant describes a shaving blade for dry razors made of sheet metal or a sheet metal alloy and has perforations with intermediate webs running through the sheet metal, the intermediate webs appear domed when viewed in a transverse cross-section. The base of the arched profile is practical flat and of uniform thickness (t) while the edges of the curved profile run at an obtuse angle to the base and with coplanar, parallel to the base Surfaces end. The width (w) of these side sections in the transverse direction is not greater than the thickness (t).

Various forms of sheet metal have been proposed and used in practice. For example describes British Patent No. 845 832 a metal foil whose thickness (from the front to the back) is right next to the Openings exceeds the thickness of the sections located between the openings.

Various methods of making shear blades have been proposed and used. For example were disclosed in U.S. Patents No. 3,498,891, 3,655,528, 3,655,529 and 3,695,927 galvanic processes are proposed. Even stamping processes have been suggested, for example in U.S. Patent 3,216,286. British Patent 1,056,038 is an option Process before in which a flat stainless steel plate is coated with a light-sensitive lacquer or photoresist and through

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INSPECTED

exposing a mask with suitable openings; then the uncured portions of the photoresist become removed to expose the steel. Then the plate is bent to the desired shape and the steel is made etched through, whereupon the hardened sections are removed by burning to obtain the shear blades. The shear blades are preferably hardened by heating to 1020 ° G, rapid cooling, and immersion in liquid air and tempering at 200 ° C.

In an earlier, British Patent No. 845 832 sheet metal is chemically or electrochemically etched so that openings with edges are created, which extend from the inside of the plate, on which the cutting section rests in turn. The ones in the photoresist on the outside appearing openings are grouped together; Photoresist applied to the inside defines islands, each of which is assigned to a group. Is etched up less than half the thickness of the sheet metal has been removed; then the etching is stopped and the photoresist is applied applied to the entire inside including the etched-out depressions. Then the etching is resumed, to etch holes through from the outside; the etching continues until each group of openings is just one single hole, which is surrounded on the inside by a notched edge.

However, there were constant attempts to find new methods

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Manufacture of Seherblatterη to develop.

The aim of the present invention is to provide a new process for the production of perforated metal foils for dry razors to accomplish.

According to the inventive method for producing shear blades for dry razors from sheet metal Sheets with a front and a back received, the perforations from the front to the back have, between which intermediate webs are located, which appear arched in the transverse cross-sectional profile. the recessed base of the arched profile is practically flat and of uniform thickness, while the edges of the arched Profile run at an angle to the base and end in coplanar, parallel to the base end surfaces. At the In the method according to the invention, a layer of a photosensitive material is applied to each side of the metal sheet, the front is then exposed to radiation through a mask with a hole distribution that corresponds to the desired Corresponds to perforations of the shear blade; subsequently becomes the back is irradiated through a mask that corresponds to the recessed base of the arched profile. The light sensitive Material is designed to preserve the respective pattern of exposed sections on both sides of the sheet metal, the unprotected sections of the front and the back are etched, the photosensitive layer is removed from the Front side removed, the front side is then further etched,

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until a certain amount of metal has been removed and the Edges of the ridges are smooth and rounded, and finally, the remaining masking material is removed.

The invention is described in detail with reference on the attached drawings.

Figure 1 is a cross section through a web on a known metal foil.

Figure 2 is a cross section through a web on one Metal foil according to the aforementioned copending application.

Finally, FIGS. 3 and 4 are cross-sections showing two stages of the method according to the invention.

As can be seen from FIGS. 1 and 2, the metal foil has recesses 1 and webs 2 lying between them. In the cross-sectional profile, the webs 2 are curved, with a flat base section 3 of the pick t and side portions 4 which extend at an angle Of to the base. The side sections 4 end in the surfaces 5, which are coplanar and parallel to the base section 3 and have the width w. It surrender so that the wells 6 on the webs.

In the known arrangement shown in FIG. 1, w is greater than t and the angle oc is a right angle.

According to the invention described in the applicant's co-pending patent application, which is shown in FIG is, w is not greater than t. In other words, w can be the same as t or less than t.

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262391S

The foils are made from a single metal or metal alloy such as steel.

The use of a single material for the invention Production of the metal foils enables the use of an advantageous etching process. The procedure is in is described below with reference to FIGS. 5 and 4.

In this process a strip 10 of suitable metal, e.g., sheet steel, is cleaned to remove grease and others Remove contaminants from the surfaces, and then by dipping with a layer of a suitable photosensitive Negative or positive varnish coated on each side. A suitable photographic negative resist is available from the company Philip A. Hunt Chemical Corporation under the designation "Waycoat-450". Another suitable photographic negative resist is marketed under the name "KMER" by the Kodak company, while a photo-positive varnish is sold by the Shipley Chemicals Ltd. is supplied under the designation AZ 111. The layers 11 and 12 are made of photoresist cured by heating. The strip 10 that results at this point in the manufacturing process is shown in FIG Figure 3 shown. The two layers are then irradiated with ultraviolet light through suitable masks in analogy to exposed and developed photographic film with clear and opaque sections. In the event of of a negative photoresist, the mask has on layer 11 opaque areas according to the desired distribution

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the openings 1, while the mask at layer 12 is opaque Has sections corresponding to the depressions 6. Of course care must be taken for the exact alignment of the masks wear so that the openings 1 and the depressions 6 have the correct positions in the finished article. After his Exposure, the photoresist is developed and cured. The strip 10 then has covered areas 11a on one side and on the other hand, covered areas 12a (see Figure 4).

The side of the workpiece provided with the covered areas 12a (which form the rear side of the metal foil) becomes then subjected to spray etching to form the recesses 6. After these have been etched out to the correct depth are, the workpiece is washed and dried and the freshly etched surface is covered with a protective film 13, for example made of tape, covered.

Then the side provided with the covered areas 11a (which form the front side of the metal foil) is made the workpiece is subjected to a spray etch which is terminated once the metal has been etched away on the mold 14, i. shortly before the openings are fully formed.

After rinsing, the covered areas 11a are removed, leaving the areas 12a and the protective film in place. You can also use the two areas covered 11a and 12a and the protective film 13 are removed and another protective coating, for example a shellac layer,

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can be attached to the side carrying the depressions will. More metal is removed by further etching the unprotected side (i.e. the front). Included the edges of the webs 2 are rounded and a metal foil with openings 1 and webs 2 is obtained If chemical polishing is required, the protective film is removed and the finished film is rinsed and dried.

The following example relates to a preferred embodiment of the production of the shear blades according to the invention.

Example. A steel strip is cleaned intensively, first at room temperature with ultrasound in a chlorinated solvent such as trichlorethylene or preferably trichloroethane, and then dried by blowing on it. After that, alkaline cleaning is carried out in a hot, degreasing salt solution with stirring; it is then rinsed with water. A salt suitable for this purpose is the Metex TS 40A salt from MacDermid, which is expediently used at a temperature of about 40.degree. The plate is then cleaned electrolytically in a cold, alkaline, cyanide-free solution, for example in the Oxyprep-285 solution from Oxy Metal Finishing Co .; then it is rinsed with water. After neutralization with dilute 18 $ hydrochloric acid, washing with water, and rinsing with deionized water and isopropyl alcohol, the plate is finally dried in the vapors of a chlorinated solvent, e.g. trichloroethane.

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Then both sides are covered with a layer of Waycoat-450 photoresist by dipping in Waycoat 450 solution coated with Waycoat PF thinner to achieve the the required viscosity has been diluted to the correct thickness of the photoresist. After an optional air drying of the coated plate, the photoresist is exposed for 10 minutes at 95-100 ° G in a convection oven or 2 Cured for minutes at 350 ° G in an infrared drying unit. The photoresist on each side of the plate is then irradiated with ultraviolet light through masks; the masks are made of exposed photographic material with transparent and opaque areas produced. On the side that finally represents the front of the metal foil and the is provided with layer 11 (see Figure 3), the transparent areas correspond to the areas 11a (see Figure 4); on the side which ultimately represents the rear side of the film and which is provided with layer 12 corresponds to the transparent ones Areas in areas 12a. Optimal exposure gives a hold of 6 to 7 levels after exposure through a Stauffer sensitivity guide with 21 levels or through eJren Kodak Mr. 2 step wedge.

After exposure, development can be carried out by spraying and immersion. The exposed Photoresist with Waycoat-PF-Developer, Waycoat-PF-Thinner and water and then allowed to air dry. The developed photoresist is then 10 minutes

at 120 ° C in a convection oven or 2 minutes Cured at 350 C in an infrared radiation unit.

After that, the etching is carried out, for which purpose it is expedient a device for two-sided spray etching is used, for example that from Chemcut Corporation device placed on the market. The etch can be done with the Waycoat-Pl etchant, but it is convenient a 48 ° -Beaume solution of ferric chloride heated to 52 ° C has been heated to use.

The first etching step for producing the depressions 6 takes 20-40 seconds. Then it is done with deionized water washed and dried by blowing with nitrogen. Then a protective layer of cellulose acetate adhesive tape 13 appropriate. The second etch is then carried out in order to remove the metal up to position H. This will be 100-140 Etched for seconds and then washed with deionized water and dried by blowing with nitrogen.

The covered sections 11a are then stripped with Kodak CP 13 LS solution removed; Depressions 6 and covered areas 12a are protected with a protective layer 13. the Final etching takes place with the same etchant and at the temperature given above. The final etch takes about 40 Seconds; it is then washed with deionized water and dried by blowing with nitrogen.

Chemical polishing can then be carried out with one suitable for the metal of the strip 10

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.Polishing solution. Suitable polishing solutions are, for example in Volume 1/2 of the "Handbook of Electroplating" by Dettner and Elze, published by Carl Hauser Verlag, Munich, described.

Finally, protective layer 13 is removed and the remaining covered areas 12a are with the help removed from the Kodak LS-13 stripper solution. Uach wash with Water and blowing nitrogen to dry, the production of the metal foil is finished.

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Claims (4)

PATENT CLAIMS Λά A method for producing shear blades for dry razors from a sheet of metal, the shaving blade having a front and a back and perforations running from the front to the rear with intermediate webs which are curved in a transverse cross-sectional profile, with a set-back base of the curved profile that practically is flat and of uniform thickness, and with edges of the curved profile which are at an angle to the base and terminate in coplanar surfaces parallel to the base, characterized in that a layer of photosensitive material is applied to each side of the metal sheet, that the The front side is exposed to radiation through a mask with a pattern of holes corresponding to the desired perforations of the shear blade, that the rear side is exposed to radiation through a mask with a pattern corresponding to the recessed base of the curved profile, so that the photosensitive material is developed ird, in order to produce the appropriate distribution of unprotected areas on each side of the metal sheet, that the unprotected areas on the front and back are etched, that the photosensitive layer is removed from the front, that the front is etched further until one certain amount of metal has been removed and the edges of the intermediate webs 60988 4/1047 are smoothly rounded, and that finally the remaining Masking material is removed. 2. The method according to claim 1, characterized in that the photosensitive material is a photo-positive lacquer. 3. The method according to claim 1, characterized in that that the photosensitive material is a photographic negative lacquer and that an additional cover layer on the back is attached after the recessed base of the curved profile has been etched out and before the photoresist layer of the front is removed. 4. The method according to any one of the preceding claims, characterized in that the back is etched first to create the recessed base of the arched profile, and that the face is then etched. 609Ü8 4 / 1CK? Blank page