A METHOD FOR MAKING A RAZOR

Abstract: A method for making a disposable razor having a blade (B), blade support means, a handle means (25) and blade covering means (26). The method comprises mating the blade (B) to a blade support (20), the blade support (20) forming at least part of at least one of said support means, handle means (25) and covering means (26), and covering a longitudinally central part of one surface of said blade (B). The remaining components are then moulded around the blade support (20) and blade (B).

Description: This invention relates to a method for making a razor, more particularly a disposable razor. Currently, disposable razors provide a substantial portion of the market for wet shaving. As used herein the expression disposable razor refers equally to a razor having a razor head with an integral handle, and to a razor having a disposable razor head (i.e. a cartridge) which can be removed from the handle. In general, the razor head comprises a blade cover, a blade seat, one or more blades and a spacer between adjacent blades. With the exception of the blade or blades (and possibly the spacer), disposable razors are made out of a thermoplastics material. The various components, depending upon the ultimate design, are moulded separately and then assembled. For example, the "MicroTrac" disposable razor manufactured by Gillette moulds a single unit blade seat, back and cap, with the cap being in the form of fingers. The blade subassembly consisting of two blades and a spacer is inserted between the moulded cap and seat with the finger-like projections extending from the top of the cap serving as leaf springs to retain the blade subassembly by a friction fit. This combination is then mated to a handle by press fitting into a tab-finger combination. It is apparent that this process involves not only separate steps but separate work stations requiring individual subassembly and ultimately assembly. Other assembly processes for disposable razors utilize staking from projections depending either from the cap or the seat which mate with reciprocal openings in the other part and position the blades and/or spacer. The handle is usually mated separately to the seat portion. Again, separate assembly steps at different locations are required to produce the disposable razor. Ultimately, a disposable razor which could be assembled at a single work station having all of the plastic parts produced in a single cavity would be desirable because the steps of subassembly, final assembly and the conveying of the various components from location to location around the manufacturing area could be eliminated. GB-A-1,565,296 discloses making a unitary handle, guard member and blade support and then attaching a Z-shaped blade by upset rivets or the like. US-A-4,489,627 describes a razor manufacturing process in which a double edge strip of blade metal is parted along a centre line and cropped to form two strips each containing a series of spaced apart blades connected by webs to an elongate backing strip. Each strip, which now consists of a plurality of blades and a backing strip, is fed into a moulding machine in which either the shaving unit, or blade containing component of a razor, is moulded directly around each individual blade. The web is then parted to release the moulded razor, etc. from the backing strip. It is not clear in this patent how the remaining razor components are manufactured. It is apparent, however, that the moulding machine completely surrounds the blade segment during moulding. This therefore requires the handling of an elongated metal strip, its control and insertion in either a multi-cavity mould or a very large single cavity mould, and the production of either a series of razors or heads joined together in a single unit which must be subsequently disassembled. Conveying of a metal web of the type described is extremely difficult when it is necessary to protect a delicate cutting edge and even more so when two cutting edges must be protected. According to one aspect of the present invention there is provided a method for forming a disposable razor having blade support means, blade covering means and optionally handle means comprising forming a blade support to mate with a blade such that the blade support extends downward from the blade at its central back portion, characterised by:- a) forming the blade support with a first shot injection moulding to mate with the blade which is set in a predetermined position in a mould such that the blade support terminates before the longitudinal ends of the blade; and b) subsequently moulding the remaining parts of the razor including a cap and a guard bar around the blade support and blade within the same mould. Preferably the blade is attached to the blade support at the time the blade support is formed. The blade support need not cover only the one surface described above. The blade is desirably mated to the blade support by allowing fluid thermoplastics material forming of the blade support to flow through at least one orifice of the blade to cover a portion of the opposite surface of the blade surrounding the or each orifice. The blade support preferably comprises at least part of the handle means. It is desirable that the entire razor is formed continuously in a single mould cavity. The remaining parts of the razor are advantageously moulded to said subassembly in a single step. According to a further aspect of the invention there is provided a razor subassembly comprising a razor blade and a moulded blade support said blade support being positioned centrally longitudinally along one surface of the blade characterised in that the blade support is moulded upward through and around at least one centrally positioned blade orifice, and terminates before the longitudinal ends of the blade. The present invention resulted from the recognition of the difficulties encountered in the attempt to mould a blade containing element which completely surrounds the blade as part of a first (or only) moulding step. It is extremely difficult to maintain the blade in a specific position while one step moulding is attempted. The blade must first, be held or retained in a specific position by some means while allowing the fluid thermoplastics material to surround the parts of the blade which are ultimately covered. One means of accomplishing this is to clamp the sharpened edge of the blade but this increases the possibility of damaging the blade. Also, if the blade is to be surrounded by moulded thermoplastics material, it is difficult to support adequately the blade during the injection of fluid and deflection or deformation of this thin metal strip is highly likely. Reference is now made to the accompanying drawings, in which:- Figure 1 is a plan view of a blade used in a method according to the invention; Figure 2 is a plan view of a blade subassembly according to the invention; Figure 3 is a view along lines 3-3 of Figure 2; and Figure 4 is a front perspective view of an assembled razor made using the method according to the invention. A blade B which is essentially conventional in configuration is used for the method of the present invention. As can be seen in Figure 1 the blade B has a first series of holes or orifices 14 and 14′ positioned near the back edge 15 of the blade B and near the longitudinal ends 12 and 12′ of the blade B. A second set of holes or orifices 16, 16′, of generally the same shape, are disposed near the longitudinal centre of the blade B and substantially symmetrically about either side of the middle of the blade B. In this particular blade the openings 14, 14′, 16 and 16′ are essentially equal in size and shape and are disposed essentially axially with respect to each other. The blade B also features a cutting edge 11 positioned on the opposite side from the back edge 15. Indentations 13 and 13′ are positioned along the longitudinal edges 12 and 12′ respectively and serve to position the blade B within an injection moulding cavity. These locating indentations 13 and 13′ provide the initial orientation to the blade for the first moulding step. A subassembly of the blade B and a thermoplastics blade support 20 is depicted in Figures 2 and 3 and is formed with a first shot injection moulding. The subassembly must have certain defined characteristics to provide the basis for subsequent moulding. The blade support 20 moulded as a single element must provide sufficient support for the blade B to prevent its undue flexing during the remainder of the process. The locating means in the form of notches 13 and 13′ are used initially to position the blade B, and then the blade support 20 is provided; this helps to minimize the blade B flexing while the blade support 20 is formed to extend downward from the bottom of the blade B at its central back portion. The support 20, enables the successful subsequent moulding of the other razor parts. The blade support 20 has a flange 21 extending downward from a support portion 24 upon which the blade B rests. In the particular embodiment depicted in Figures 2 and 3, the blade B is attached to the blade support 20 and held in place by tabs 22 and 22′ which are joined to the support 24 by downward projections 23; the projections 23 extend through the holes 16 and 16′. The top of the tabs 22 and 22′ must be controlled in height so that the subsequent formation of a cap, or the addition of a second blade or spacer is not hindered by the tabs 22 and 22′. The flange 21, the tabs 22 and 22′, the projections 23 and the support portion 24 are injection moulded to form a single component which both serves to support and retain the blade B in its position on blade support 20. It is contemplated that the downward projection 21 will, in one embodiment, form a thermoplastics handle 25 of the razor (see Figure 4). The length or other configurational features of the downwardly extending part of support 20 is not particularly critical in that it merely provides an additional basis for positioning for subsequent moulding. After the subassembly has been formed, the remainder of the disposable razor is shaped, e.g., by injection moulding, around the blade subassembly. Blade slots 14 are used to provide locations to anchor thermoplastics blade covering means in the form of a cap 26. As can be seen in Figure 4 the completed razor has a joindure of the handle 25 to downward depending part of the blade support 20. This is overlaid by the cap 26, and a guard bar 28 is moulded as a single element which is attached to, and forms part of, thermoplastics blade supporting means in the form of a blade seat (not shown in Figure 4) by ribs 29. As can be seen from the above description, several variables in process are possible within the scope of the invention. First, there is nothing particular critical about the size or number of the holes used for positioning and they can in fact be of a different size and different location as long as the blade B has limited flexibility after it has been attached and the flexibility is essentially the same on both sides of the blade centre so that there is no distortion. As previously mentioned, the downward projecting flange 21 can be of a variety of shapes and can in fact provide the handle 25. Other positioning means can be utilized instead of notches 13 and 13′ if desired, and alternative means of attachment instead of, or in addition to, the orifices 14 and 14′ are possible. Also it is possible to make a twin blade assembly by positioning either the blades or the blades and a metal spacer using positioning notches on the blade and spacer ends, or by positioning only the blades and forming a plastics spacer during the subsequent moulding step. An alternative is to mould as described above, around a previously formed and assembled composite of the two blades separated by a spacer.

Claims: A method for forming a disposable razor having blade support means, blade covering means (26) and optionally handle means (25) comprising forming a blade support (20) to mate with a blade (B) such that the blade support (20) extends downward from the blade (B) at its central back portion, characterised by:- a) forming the blade support (20) with a first shot injection moulding to mate with the blade (B) which is set in a predetermined position in a mould such that the blade support (20) terminates before the longitudinal ends (12,12') of the blade (B); and b) subsequently moulding the remaining parts of the razor including a cap (26) and a guard bar (28) around the blade support (20) and blade (B) within the same mould. A method according to Claim 1, characterised in that the blade (B) is attached to the blade support (20) at the time the blade support (20) is formed. A method according to Claim 1 or 2, characterised in that the blade (B) is mated to the blade support (20) by allowing fluid thermoplastics material forming of the blade support (20) to flow through at least one orifice (14,14',16,16') of the blade (B) to cover a portion of an opposite surface of the blade (B) surrounding the or each orifice 14,14',16,16'). A method according to Claim 1,2 or 3, characterised in that the blade support (20) comprises at least part of the handle means (25). A method according to any preceding claim, characterised in that the entire razor is formed continuously in a single mould cavity. A method according to any of Claims 1 to 5, characterised in that the remaining parts of the razor are moulded to said subassembly in a single step. A razor subassembly comprising a razor blade (B) and a moulded blade support (20) said blade support (20) being positioned centrally longitudinally along one surface of the blade (b) characterised in that the blade support (20) is moulded upward through and around at least one centrally positioned blade orifice (16,16'), and terminates before the longitudinal ends (12,12') of the blade (B). A disposable razor manufactured by the process according to Claim 1.

Inventors: BUTLIN, EDWARD C., CONRAD, WILLIAM T., JR.
Applicants: WARNER-LAMBERT COMPANY
Application year: 1988
Main classification: B26B21
IPC codes: B29C45, B26B21