WO1992006828A1

WO1992006828A1 - Razor blade units and blade spacers therefor

Info

Publication number: WO1992006828A1
Application number: PCT/US1991/007598
Authority: WO
Inventors: Brian Oldroyd
Original assignee: The Gillette Company
Priority date: 1990-10-22
Filing date: 1991-10-11
Publication date: 1992-04-30
Also published as: CA2091571C; GB9022936D0; AU661284B2; MX9101687A; JP3112939B2; JPH06502334A; EP0554365A1; BR9107005A; DE69120959T2; EP0554365A4; EP0554365B1; CA2091571A1; DE69120959D1; AU8957291A

Abstract

In or for use in a razor blade unit having two parallel blades (14) and an interposed spacer (15), a flexible spacer having spaced transverse ribs with the ribs on one side offset from the ribs on the other side.

Description

Razor Blade Units and Blade Spacers Therefor

This invention is concerned with spacers for flexible razor blade units comprising two blades in tandem, with flexible razor blade units comprising such spacers, and with safety razors comprising such blade units.

Tandem razor blade units which are flexible, in response to forces encountered during normal use, about an axis or axes parallel with the plane of the blades and extending substantially perpendicularly to the cutting edges of the blades have been described in a number of patent specifications, for example, British Specifications 1589591 and 2119690.

The flexibility of such a blade unit can be assured by the design of the moulded plastics housing in which the blades and spacer are mounted, by the use of blades which are thinner than conventional, and by the design and material of the blade spacer. The spacers which are conventionally used in non-flexible blade units are formed of 0.02 inch (0.51 mm) thick aluminum; the use of such a spacer in a blade unit which was, in other respects, flexible would stiffen it to such an extent that it would not flex in shaving and it has accordingly been recognised that in a flexible blade unit, the spacer should be made of a flexible, preferably plastics, material.

We have now developed spacers which provide tandem razor blade units with improved flexibility.

According to the present invention, there is provided a spacer for a flexible razor blade unit comprising two blades in tandem, which comprises a flexible plastics strip having a length and width appropriate to the blades with which it is to be used, the major surfaces of the strip being formed with transverse ribs, the ribs on one side of the strip being offset with respect to those on the other side and the thickness of the strip and two ribs being greater than the desired separation of the blades.

According to another aspect of the invention, there is provided a flexible tandem razor blade unit, which comprises a flexible moulded plastics housing providing a guard portion and a cap portion and in which tandem blades and a spacer according to the invention therebetween, are clamped under compression.

In such a unit, the guard portion and the cap portion preferably have a comb-like form, the teeth of the two comb-like portions being interconnected by a web which is sufficiently thin as to be flexible.

According to a further aspect of the invention, there is provided a safety razor comprising a flexible tandem blade unit according to the invention, a handle, and connecting means connecting the blade unit to the handle which means permit flexing of the blade unit.

The spacer according to the invention is preferably formed of polyethylene. In addition to its cheapness and good moulding properties, polyethylene has the advantage of a very low coefficient of friction against steel so that the blades can move easily against the spacer as the blade unit is flexed. It is preferred that the height of the ribs should be such that the thickness of the strip and two ribs should be greater than the desire separation of the blades by less than the height of a rib. For the better understanding of the invention, a currently preferred embodiment thereof will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a flexible tandem razor blade unit which also show the blades and spacer thereof prior to assembly in the unit.

Figure 2 is a partial longitudinal section of the spacer shown in Figure 1, and Figure 3 is a partial longitudinal section of the blades and spacer shown in Figure 1 as clamped in the unit.

Referring to the drawings, a flexible tandem razor blade unit 10 comprises a flexible moulded plastics housing 11 providing a guard portion 12 and a cap portion 13 and in which tandem blades 14 and a spacer 15 therefor, are clamped under compression. The spacer 15 is a flexible plastics strip 16 of moulded polyethylene having a length and width appropriate to the blades with which it is to be used, for example, a length L of 37.50 mm and a width W of 2.04 mm. Both sides of the strip are provided with integrally moulded transverse ribs 17, the ribs on one side being offset with respect to those on the other side (see Figure 2) . one long edge of the strip 16 is provided with spaced teeth 18 lying in the plane of the strip.

In a particular embodiment the ribs 17 are separated from each other by a distance P of 2.5 mm, the thickness T_χ of the strip 16 is 0.30 mm and thickness T, of the strip and two ribs is 0.51 mm, so that the height of each rib is 0.105 mm.

In this embodiment, the spacer is used with blades 14 having a thickness of 0.0813 mm so that the uncompressed thickness of the assembly is 0.51 mm + 2 x 0.0813 mm, that is 0.6726 mm. When mounted in the housing 11 this assembly is compressed to the form shown in Figure 3 and has a thickness T₃ of 0.64 mm, that is there is interference of about 0.033 mm to give blade clamping.

The blades 14 and the spacer 15 are retained in the correct position in the unit 10 by protrusions (not shown) in the housing 11 and protrusions 19 on the spacer which engage in slots 20 in the blades. Slots are used so as to allow relative movement of the blades and spacer during flexing.

The offset rib arrangement in the spacer according to the invention provides good compressibility and thus facilitates assembly of the blade units and improves blade clamping. This arrangement is also such that friction between the spacer and the blades during flexing is minimized by the fact that the area of contact is substantially only the surfaces of the ribs 17.

When the blade unit shown in the drawing is connected to a handle by means permitting flexing of the blade unit, it is found that the latter has excellent flexibility.

Claims

C LA I M S

1. A spacer for a flexible razor blade unit comprising two blades in tandem, which comprises a flexible plastics strip having a length and width appropriate to the blades with which it is to be used, the major surfaces of the strip being formed with transverse ribs, the ribs on one side of the strip being offset with respect to those on the other side and the thickness of the strip and two ribs being greater than the desired separation of the blades.

2. A spacer according to claim 1, in which the thickness of the strip and two ribs is greater than the desired separation of the blades by less than the height of a rib.

3. A spacer according to claim 1 or 2, in which one long edge of the strip is formed with spaced teeth lying in the plane of the strip.

4. A spacer according to any of claims 1 to 3, which is formed of polyethylene.

5. A flexible tandem razor blade unit which comprises a moulded plastics housing providing a guard portion and a cap portion and in which tandem blades and a spacer according to any of claims 1 to 4 therebetween, are clamped under compression.

6. A blade unit according to claim 5, in which the guard portion and the cap portion have a comb-like form, the teeth of the two comb-like portions being interconnected by a web which is sufficiently thin as to be flexible.

7. A safety razor comprising a flexible blade unit according to claim 5 or 6, a handle, and a connecting means connecting the blade unit to the handle which means permit flexing of the blade unit.