RAZOR HEAD

Abstract: A razor head (10) comprises a cap (11) having an upper and lower surface, a seat (25) having an upper and lower surface, and at least one blade (13, 14) with apertures. The or each blade (13, 14) is maintained in a predetermined position between the upper surface of said seat (25) and the lower surface of said cap (11) by pins (12) passing through each of the apertures. The pins (12) either depend upward from the upper surface of the seat (25) into mating apertures on the lower surface of the cap (11) or downward from the lower surface of the cap (11) into apertures on the upper surface of the seat (25). At least some of said pins (12) have a skirt (21) positioned either above at least part of the upper surface of said cap (11) or below at least part of the lower surface of said seat (25).

Description: This invention relates to a razor head and to a method of assembling the same. Razor cartridges and the non-handled portion of disposable razors (both of which are hereinafter referred to generically as razor heads) generally consist of a blade support surface with a guard bar extending from its leading edge, a single blade or a pair of blades which may be separated by a spacer element, and a cap. The blades, in one method of assembly, have orifices and are positioned over pins extending upward from the top of the blade support surface or downward from the cap. If the pins depend downward from the cap they extend through the blade support surface and are anchored in the bottom of the blade support. US-A-4,205,437 depicts such an assembly. US-A-4,535,537 discloses a system whereby the staking means are positioned in the blade support surface and extend upward through the bottom of the blade to engage the surface on the top portion of the blade. In both of these instances, the component parts of the razor head are locked in place by applying a force to the bottom of each pin to deform the bottom and spread it out into a rivet-like configuration having a wider diameter than that of the adjacent part of the pin. The cold riveting operation can bend, deform or at times even crack the pin. This is even more likely if the force is delivered to the point of the pin and is not applied equally across the bottom profile. US-A-4,443,939 discloses staking with a "pop bead" approach. In this instance a pin having an inwardly tapering diameter as it extends downward terminates in a solid spheroid. The orifices positioned in the receiving portion of the blade support surface, have a chamfered area around the orifice. Because of the reduced thickness in the chamfered area, the spheroid at the end of the stake, which is larger in diameter than the orifice, can be pushed through the orifice by deflecting the chamfered area downward. In theory, the chamfered area then springs back and positions itself around the area of tapering reduced thickness immediately preceding the sphere. The spheroid takes the place of the staking rivet and eliminates the stresses put on the pin by the riveting operation. Unfortunately, in a number of cases, the chamfered area is deflected downward but, after passage of the enlarged spheroid, does not spring back, but remains in the downwardly deflected configuration. This bending widens the hole and eliminates the secure locking fit required for razor head assembly. US 3890 704 discloses a razor cartridge in which the blade is properly aligned and secured between the cap and the seat by posts which pass through apertures in the blade and seat. The posts initially have an outer longitudinal dimension equal to or greater than the longitudinal dimensions of the apertures and an outer transverse dimension less than the transverse dimensions of the apertures to provide a longitudinal interference fit of the posts in the apertures. The components must subsequently be bonded together. According to this invention a razor head comprises a blade or blades, a cap and a blade seat secured together by staking means attached to either the cap or the seat and extending through the blade or blades into the other of the cap or seat, the staking means being provided with a skirt which extends beyond at least part of the upper surface of the cap or the lower surface of the seat. The skirt provides a locking assembly for the component parts of the razor head. The aperture may be any conventional form of hole provided in razor components and includes orifices and slot-shaped orifices. For the purposes of this invention skirt is used to describe, inter alia, a radially disposed symmetrically positioned area of increased radial width positioned slightly upward from the end of the staking means bottom and used to abut against a downwardly deflected chamfered area from below. For the purposes of this invention a skirt is defined as an area preferably symmetrically disposed radially around the staking means which may be continuous or discontinuous and located slightly upward from the end thereof. The staking means is typically in the form of stakes or pins. The locking is achieved without the possibility of bending, deforming or shattering the individual stakes or pins themselves. According to one aspect of the invention there is provided a razor head comprising a razor head comprising a cap having an upper and lower surface, a seat having an upper and lower surface, and at least one blade with apertures, the or each blade being maintained in a predetermined position between said upper surface of said seat and said lower surface of said cap by pins passing through each of said apertures either depending upward from said upper surface of the seat into mating apertures on said lower surface of the cap or downward from said lower surface of the cap into apertures on said upper surface of the seat, at least some of said pins having a skirt positioned above at least part of said upper surface of said cap characterised in that the skirt can alternatively be positioned below at least part of said lower surface of said seat, and that the skirt of each pin is formed above the bottom end of said pin. According to another aspect of the invention there is provided a process for assembling a razor head utilizing at least one blade with orifices and staking means extending either from a cap or a seat wherein either the seat or the cap has orifices for receiving said staking means including a) aligning the blades on said staking means; b) uniting the receiving orifices with said staking means so that the end of said staking means protrude beneath said element; characterised by c) contacting said protruding portion with a skirting fixture to form a skirt which locks the components of said head into place, said skirt being formed above the bottom end of the staking means. Reference is now made to the accompanying drawings, in which:- Figure 1 is a front perspective view of a razor head Figure 1 is a front perspective view of a razor head according to the invention; Figure 2 is a view partially in cross-section taken along lines 2-2 of Figure 1; and Figures 3 and 4 are representational views of the forming steps used for the skirt of this invention. A typical disposable razor is shown in Figure 1 in which a razor head 10 is connected to a handle 18 by connecting portion 17. A fingered cap 11 overlies a first or cap blade 13 having a cutting edge 13'. A second or seat blade 14 has a blade cutting edge 14' extending parallel to and outward from cap blade cutting edge 13'. The first and second blades 13 and 14 are separated by a spacer element 27 (see Figure 2). Cap sides 15 cover the blades 13 and 14 at their transverse edges to prevent the edges from gouging the user. A guard bar 19 is connected to a blade seat portion 25 (see Figure 2) by three outstanding ribs 16. The guard bar 19, ribs 16 and seat portion 25 provide a unitary blade support portion. Staking means are provided in the form of pins 12. The head of the pins 12 (shown in phantom lines in Figure 1) depends downward through mating orifices in cap blade 13 spacer 27 seat blade 14 and seat 25. A skirt 21 extends radially circumferentially from a shaft portion 20 of the pin 12 positioned near a spheroidal bottom 22 of the pin shaft 20. As can be seen in Figure 2, the area of the seat 25 adjacent a necked portion 23 of the pins 12 is deflected downward because the diameter of the pin 12 is slightly greater than the diameter of the aperture 29 in blade seat 25. This downward deflection is much more likely to occur when the seat 25 is chamfered, if the thickness of the seat 25 is generally reduced, but it can occur without chamfering. Turning now to Figures 3 and 4, Figure 3 shows a pin 12 such as that used in the "pop bead" configuration having a necked portion 23 and a bulbous bottom portion 22. The pin 12 is directed towards a fixture 30 having shoulders 31 and deforming, skirt-forming slot 32. As the pin shaft 20 is driven downward through the seat 25 it initially engages fixture 30 and forces the bulbous portion 22 in contact with the edge of shoulders 31. The downward directing force pushes the portion 22 of the pin 12 which is wider than slot 32 upward and outward to form the skirt 21. After the skirt 21 is formed, the fixture 30 is lowered from the area directly beneath the bottom portion of seat 25 leaving the pin 12 with skirt 21 positioned above the bottom portion 22 of the pin 12 and, in the case where the pin 12 having a necked portion 23 is utilized, the skirt 21 is formed directly below the necked portion 23. While the skirt forming method described above can be practiced on pins having substantially uniform diameter along their length it is preferred to utilize a pin similar to that used in the pop bead configuration because less stress is placed on the pin along its length. The shear forces exerted on the pop bead type of pin exists primarily on the sides of the pin and therefore distribute forces essentially uniformly i.e., staking process is confined to a portion of the pins total cross-sectional area thereby reducing the staking forces. It is also desirable to use chamfered areas around the orifices 29 of the seat 25 because the downwardly deflected surfaces area of the seat 25 helps to maintain the locking configuration. While it is possible to generally bend the areas in the seat near the hole, by providing specific areas of reduced thickness and, concomitantly, decrease resistance to downward forces exerted by pushing the stake through the orifice, a more consistent locking system is formed. It will be appreciated that the pins 12 could instead be provided on the seat 25 so that their ends 22 project upwardly through orifices provided in the cap 11.

Claims: A razor head (10) comprising a cap (11) having an upper and lower surface, a seat (25) having an upper and lower surface, and at least one blade (13,14) with apertures, the or each blade (13,14) being maintained in a predetermined position between said upper surface of said seat (25) and said lower surface of said cap (11) by pins (12) passing through each of said apertures, characterised in that said pins are either depending upward from said upper surface of the seat (25) into mating apertures on said lower surface of the cap (11) or downward from said lower surface of the cap (11) into apertures on said upper surface of the seat (25), at least some of said pins (12) having a skirt (21) positioned either above at least part of said upper surface of said cap (11) or alternatively positioned below at least part of said lower surface of said seat (25), and that the skirt (21) of each pin (12) is formed above the bottom end of said pin (12). A razor head (10) according to Claim 1, characterised in that there are four pins (12) with two disposed symmetrically on each side of the traverse centre of the head (10). A razor head according to Claim 1 or 2, characterised in that the outermost pins (12) have skirts (21). A razor head according to Claim 1 or 2, characterised in that all the pins (12) have skirts (21). A razor head according to any preceding claim, characterised in that the pins (12) depend from the lower surface of said cap (11). A process for assembling a razor head (10) utilizing at least one blade (13,14) with orifices and pin-like staking means (12) extending either from a cap (11) or a seat (25) wherein either the seat (25) or the cap (11) has orifices for receiving said staking (12) means including a) aligning the blades (13,14) on said staking means (12); b) uniting said receiving orifices with said staking means (12) so that the end of said staking means (12) have a portion (20) protruding beneath said cap or said seat; characterised by c) contacting said protruding portion (20) with a skirting fixture to form a skirt (21) which locks the components of said head (10) into place, said skirt (21) being formed above the bottom end of the staking means (12).

Inventors: BUROUT III, CHARLES JOHN
Applicants: WARNER-LAMBERT COMPANY
Application year: 1988
Main classification: B26B21
IPC codes: B26B21