GB2059995A - Jet plating of cutting instruments - Google Patents

Abstract

A cutting instrument such as a razor blade has at least one cutting edge 12 and a guard comprising a plurality of spaced jet-plated elements 13 on at least one facet thereof, said elements extending beyond the edge substantially in the plane of the blade. <IMAGE>

Description

SPECIFICATION Jet plating of cutting instruments This invention relates to cutting instruments such as razor blades.

For as long as man has attempted the removal of hair from the body, energies have been directed to amelioratig the effects of the sharpened cutting edge on the skin of the user. Despite all efforts, occasional skin irritation and bloodletting still occur during the shaving process.

Hitherto numerous methods have been devised to minimise this aspect of shaving, a large portion directed to improved forms of edge guard. U.S. Patent No. 1.035.548 discloses a straight razor having a long blade on which is spirally wound a wire or thread to form a guard. Another form of guard is disclosed in U.S.

Patent No. 3.263.330 wherein the razor blade cutting edge is encapsulated in a folded sheet of metal having a row of holes through which the hairs but not the skin pass for cutting.

A more recent development is disclosed in U.S. Patent No. 3.505.734 for a cutting blade with self-contained guard. In this patent a razor blade with a self-contained guard in the form of a wire is described. The wire or thread of selected diameter is wound about the body of the blade encompassing its ultimate edge. The spacing or pitch between successive turns of the wire is controlled relative to its diameter to provide protection to the skin of the user and diminished probability of cutting or nicking. With the selected critical thread diameter and spacing between successive thread portions at the cutting edge the blade may be drawn across the skin without coming into contact therewith, but the manufacture of such razor blades involves many severe problems.For example, the thread must be of flexible material having precise dimensional conformity and it must also be sufficiently flexible for winding about the body of the blade and yet strong enough to withstand severing as it passes over and comes in contact with the blade edge.

Moreover, once the wire is placed on the blade it must be adhesively or otherwise locked into position to prevent interference with shaving and to maintain its advantageous characteristics.

According to one aspect of the present invention, we provide a cutting instrument such as a razor blade having at least one cutting edge and a guard comprising a plurality of spaced jet-plated elements on at least one facet thereof, said elements extending beyond the edge substantially in the plane of the blade.

According to another aspect of the present invention a razor blade has at least one cutting edge, the guard comprising a plurality of spaced jet-plated structural elements deposited on at least one facet thereof, said elements extending beyond the edge substantially in the plane of the blade.

Structural elements are preferably electroplated on the blade edge and desirably extend approximately 12 microns to approximately 100 microns beyond the blade edge and conveniently are spaced apart between 350 and 750 microns.

The deposited structural elements are preferably metal and may be, for example, copper.

If desired the edge and the structural elements may be coated with an adherent film of a low conduction material such as polytetrafluoroethylene.

According to a further aspect of the invention, a method for forming a guard over a razor blade edge comprises the steps of disposing the blade in a predetermined position, and jetting a plating fluid thereon in a controlled manner to form a plurality of spaced guard elements.

Preferably the plating fluid is electrically conductive and is dispensed from a nozzle, and the method includes the steps of applying an electrical potential between said nozzle and said blade, and so spacing the nozzle from the blade and applying a pressure with which the fluid is expelled from the nozzle such that a continuous stream of fluid is established therebetween, thereby completing an electrical circuit.

If desired the blade may be moved with respect to the fluid stream to achieve a desired structural element dimension.

The blade may be pre-treated in a nickel strike bath, including jet plating nickel on to said blade only where said structural elements are to be subsequently jet plated.

Conveniently, the guard comprises a plurality of spaced metallic elements and the cutting instrument is connected as a cathode.

The spaced elements may be produced by successive plating steps from one or more jets or may be produced simultaneously by a plurality of jets.

Referring to the accompanying drawings: Figure 1 is a diagrammatic perspective view of a cutting edge of a razor blade with a guard according to the invention; and Figure 2 is a schematic diagram of a device for forming a guard on a cutting edge of a razor blade.

Referring to Figure 1 a razor blade 10 is shown having at least two intersecting facets 11 forming an ultimate shaving edge 12. Arranged transversely to the ultimate edge 12 are deposited spaced elements 13 passing over the edge 12 and extending down the face of facets 11 towards the body of the blade 10. The spaced elements 13 are respectively spaced along and throughout the longitudinal axis of the blade 10.

An organic polymer coating (not shown in Figure 1) may be distributed over the entire edge structure in order to facilitate hair cutting and shaving comfort.

Figure 2 shows in schematic form the equipment necessary to provide the spaced elements. It comprises a nozzle formation 20 communicating with a bath of electrolyte 21 and arranged to produce a jet 22 of electrolyte towards a blade 23 to be provided with a guard.

As shown the electrolyte is connected as an anode to a source of electric current and the blade 23 is connected as a cathode. It is important when using a jet plating technique that a continuous jet is maintained before contacting the cathode, since if the jet breaks up into a stream of droplets, the electrical circuit will be broken and no plating will take place. The jet is produced by applying sufficient pressure to the electrolyte for the jet to bridge the gap between the nozzle 20 and the blade 23 without breaking up into a stream of droplets.

The method of the present invention is particularly convenient if used in conjunction with an aqueous cleaning technique since the guard elements may be applied to the blade before the blade is dry.

In one particular example applied to a razor blade, the blade was pretreated in a nickel strike bath of the following composition: nickel sulphate 250 gms.

sulphuric acid 50 gms.

water added to 1000 ml.

The blade was first connected as an anode and anodic cleaned for 2 minutes at 200 mA. It was then reconnected as a cathode and jet plated for 5 minutes at 200 mA only where the elements 13 are to be plated subsequently.

The pretreated blade was mounted in a nylon holder and brought up to a jet stream issuing from a jet plating nozzle, the precise position being adjusted to give the desired result.

The nozzle employed was a 30 um platinum aperture mounted in a stainless steel nozzle holder. The electrolyte was pressurised to a pressure of 80 psig and supplied to the nozzle via a 0.5 Mm filter which is employed to reduce the tendency for nozzle blockage to occur. The plating solution employed was as follows: Copper sulphate 200 gms.

Potash alum 12 gms.

Sulphuric acid 56 gms.

Water added to 1250 ml.

Typical separation of the cutting edge from the nozzle was found to be between 1 mm and 3 mm.

Satisfactory results with this particular nozzle size were obtain using plating times falling between 2 secs.

and 60 secs., although it will be appreciated that these times will vary depending on the other process conditions. Plating currents which were employed were generally between 100 A and 400 FlA.

It will be appreciated that the use of a jet as described above would provide only a single guard element on the cutting edge. A plurality of spaced guard elements could be provided by advancing the blade between plating operations, by providing spaced nozzles to produce all the guard elements simultaneously, or by a combination of these two procedures.

It will be appreciated that where one or more jets are used to scan the cutting edge of the blade (either by moving the blade over the nozzles) then plating in the areas intermediate the predetermined pattern of spaced guard elements may be prevented by the use of a suitable mask.

Our co-pending application No.11559/76 describes another method of providing spaced guard elements on a cutting edge of, for example, a razor blade.

Claims (17)

1. A cutting instrument comprising a blade having at least one cutting edge and a guard comprising a plurality of spaced jet-plated elements on at least one facet thereof, said elements extending beyond the edge substantially in the plane of the blade.

2. A cutting instrument according to Claim 1 in which the elements are metal elements.

3. A cutting instrument according to Claim 2 in which the elements are copper.

4. A cutting instrument according to any of Claims 1 to 3 in which the edge and the elements are coated with an organic polymer coating.

5. A razor blade having at least one cutting edge and a guard for said at least one cutting edge comprising a plurality of jet-plated structural elements deposited on at least one facet thereof, said elements extending beyond the edge substantially in the plane of the blade.

6. A razor blade according to Claim 5 in which the elements are metal elements.

7. A razor blade according to Claim 6 in which the elements are copper.

8. A razor blade according to any of Claims 5 to 7 in which the structural elements extend approximately 12 microns to approximately 100 microns beyond the blade edge and conveniently are spaced apart between 350 and 750 microns.

9. A razor blade according to any of Claims 5 to 8 in which the edge and the blade elements are coated with an organic polymer coating.

10. A method for forming a guard over a blade edge comprises the steps of disposing the blade in a predetermined position, and jetting a plating fluid thereon in a controlled manner to form a plurality of spaced guard elements.

11. A method according to Claim 10 in which the plating fluid is electrically conductive and is dispensed from a nozzle, said method including the steps of applying an electrical potential between said nozzle and said blade, and so spacing the nozzle from the blade and applying a pressure with which the fluid is expelled from the nozzle such that a continuous stream of fluid is established therebetween, thereby completing an electrical circuit.

12. A method according to Claim 11 in which the blade and the fluid stream are moved relative to one another to achieve a desired structural element dimension.

13. A method according to any of Claims 10 to 12 in which the blade is pretreated in a nickel strike bath, including jet plating nickel on to said blade only where said structural elements are to be subsequently jet plated.

14. A method according to any of Claims 11 to 13 in which the spaced elements are produced by successive plating steps from one or more nozzles.

15. A method according to any of Claims 11 to 13 in which the spaced elements are produced simultaneously by a plurality of nozzles.

16. A cutting instrument substantially as herein described with reference to and as shown in the accompanying drawings.

17. A method for forming a guard over a blade which substantially is herein described with reference to the accompanying drawings.