EP-4741096-A2 - METHOD OF FORMING A RAZOR BLADE ASSEMBLY

EP4741096A2EP 4741096 A2EP4741096 A2EP 4741096A2EP-4741096-A2

Abstract

A method of joining a razor blade to a blade support to form a razor blade assembly, the method comprising: a) selecting, for a laser scanning apparatus, values for one or more parameters comprising at least one of a spot size, a scanning speed profile, a pulse length, or a shield gas type and flow velocity, a pulse power, or a laser beam parameter product; b) operating the laser scanning apparatus in accordance with the one or more selected values to apply a laser beam to the razor blade; and c) generating an elongated weld area joining the razor blade and blade support to form the razor blade assembly, wherein the elongated weld area comprises a ratio of depth:width that is greater than about 2:1.

Inventors

HAMELIN, MICHEL DENIS
VICKERY, CRAIG STEPHEN

Assignees

The Gillette Company LLC

Dates

Publication Date: 20260513
Application Date: 20220502

Claims (12)

A method of joining a razor blade to a blade support to form a razor blade assembly, the method comprising: a) selecting, for a laser scanning apparatus, values for one or more parameters comprising at least one of a spot size, a scanning speed profile, a pulse length, or a shield gas type and flow velocity, a pulse power, or a laser beam parameter product; b) operating the laser scanning apparatus in accordance with the one or more selected values to apply a laser beam to the razor blade; and c) generating an elongated weld area joining the razor blade and blade support to form the razor blade assembly, wherein the elongated weld area comprises a ratio of depth:width that is greater than about 2:1.
The method according to claim 1, wherein the laser beam is advanced along the razor blade at a speed of at least 800 mm/second.
The method of claim 1 or 2, wherein the weld area comprises an elliptical or lozenge-shaped weld area.
The method of any one of the preceding claims, wherein the method further comprises: controlling at least one of a spot size, a scanning speed profile, a pulse length, or a shield gas type and flow velocity, a pulse power, or a laser beam parameter product to form an elliptical or lozenge-shaped weld area.
The method of any one of the preceding claims, wherein the weld area comprises a width and a depth, the method further comprising: selecting a speed for advancing the laser beam along the razor blade such that the width of the weld area is uniform along substantially an entirety of the depth.
The method of any one of the preceding claims, wherein advancing the laser beam along the razor blade comprises: fixing the razor blade and blade support in a given position and moving the laser beam, fixing the laser beam and moving the razor blade and blade support, or moving both the laser beam and the razor blade and blade support.
The method of any one of the preceding claims, wherein the method further comprises forming one or more additional weld areas by repeating (a)-(c) for each additional weld area.
The method of claim 7, further comprising: selecting a maximum scanning speed between each additional weld area such that a scanning speed within the each additional weld area is uniform and minimizes heat distortion.
The method of any of the preceding claims, wherein the laser beam is generated by a single-mode laser.
The method according to any one of the preceding claims, wherein the method further comprises: focusing the laser beam using an F-theta lens, a single-element lens, a multi-element lens, a diffractive optical element, or a holographic optical element.
The method according to any one of the preceding claims, wherein the method further comprises: breaking the razor blade to provide a tip to back blade width of between about 0.20 mm to about 1.50 mm.
The method according to any one of the preceding claims, wherein the elongated weld area is generated by keyhole welding.

Description

FIELD OF THE INVENTION The invention generally relates to welded razor blade assemblies, and more particularly to razor blade assemblies made using keyhole welding and methods of making the same. BACKGROUND OF THE INVENTION A razor blade assembly includes a razor blade joined to a blade support, in which the blade support is used to install the razor blade assembly into a razor cartridge. In current razor blade assemblies, conduction laser welding is typically used to join the razor blade to the blade support. Conduction laser welding relies on surface heating of a part to create a molten pool of material that grows in width and depth via conduction and convection processes until the molten pool reaches an underlying substrate and creates a weld area that bonds or joins the part to the substrate. The weld area created by conduction laser welding generally comprises a relatively shallow, rounded cross-section that gets narrower with depth. As such, these weld areas sometimes exhibit lower process margins. Obtaining a stronger weld with conduction laser welding typically requires increasing the size of the weld area, particularly the depth, which generally requires longer weld times and results in a weld area with a greater width. However, the increased heat associated with longer weld times can cause a number of process variations that result in defects, such as heat distortion of the part. In addition, obtaining good quality, consistent welds via conduction laser welding requires a relatively complex control strategy and frequent maintenance, including cleaning and inspection, sampling, and destructive testing to ensure optimal operation. These tasks result in increased cost and effort and often are not 100% effective in maintaining quality and consistency. CN103495803 relates to a method for laser welding an elliptical welding spot. US2020/230837 relates to mechanical shaving razors comprising a razor head, which cutting member comprises a blade that is fixed on the upper portion of the blade support by laser spot welding. WO2020/115205 relates to the attachment of razor blades to razor blade supports by laser welding. Kawahito et al., "In-process repairing in laser welding of aluminium alloy sheets. A study of adaptive control based on in-process monitoring signals" (doi: 10.1533/ wint.2006.3597) relates to laser welding technologies for aluminum alloy sheets. US 2020/230837 relates to a blade support for a shaving razor including an inner face, an outer face an elongated lower portion, an elongated upper portion, and an elongated intermediate bent portion between the lower and upper portions. The upper portion extends forward of the intermediate bent portion to a top side. The lower portion extends downward from the intermediate bent portion to a bottom side. The top side and/or the bottom side are substantially curved surfaces. SUMMARY OF THE INVENTION The invention provides a method of joining razor blades to blade supports in accordance with the claims. BRIEF DESCRIPTION OF THE DRAWINGS While the specification concludes with claims particularly pointing out and distinctly claiming the subject matter which is regarded as forming the present invention, it is believed that the invention will be better understood from the following description which is taken in conjunction with the accompanying drawings in which like designations are used to designate substantially identical elements, and in which: FIG. 1 is perspective view of a razor blade cartridge including a razor blade assembly, in accordance with the present disclosure;FIG. 2 is a schematic illustration of a top view of a razor blade assembly of FIG. 1 with a weld area formed using a keyhole welding process, in accordance with the present disclosure;FIG. 3A is a cross-section of the razor blade assembly of FIG. 2 taken along line 3A-3A;FIG. 3B is a cross-section of the razor blade assembly of FIG. 2 taken along line 3B-3B;FIG. 4 is a cross-section similar to FIG. 3A illustrating an angled weld area, in accordance with the present disclosure;FIG. 5 is a schematic illustration of a top view of a razor blade assembly with a weld area formed using a prior art conduction laser welding process;FIG. 6 is a cross-section of the razorblade assembly of FIG. 5 taken along line 6-6;FIG. 7 is a schematic diagram of an exemplary laser scanning apparatus for performing keyhole welding, in accordance with the present disclosure;FIG. 8 is an enlarged view of a portion of FIG. 7 depicting an interface between the laser beam and the workpiece and a graph illustrating a laser pulse shape, in accordance with the present disclosure;FIGS. 9 and 10 are flow diagrams illustrating exemplary methods of joining a razor blade to a blade support to form a razor blade assembly, in accordance with the present disclosure. DETAILED DESCRIPTION OF THE INVENTION The present disclosure relates to a keyhole welding process for forming a razor blade assembly comprising a razor blade and