Razor blade technology
View Patent ↗An elongated flat strip of martensitic stainless steel material for use in manufacturing razor blades is provided with an elongated weakened portion. The weakened portion is provided after hardening, sharpening and cutting edge coating processes are performed. The weakened portion is provided by the application of laser energy that forms a groove along a side of the razor blade and converts previously tempered martensite to untempered martensite in the weakened portion. The razor blade is attached to a support and removed at the weakened portion. The weakened portion can be provided before or after the razor blade is attached to the support.
1. A method of manufacturing a cutting edge portion of a discrete razor blade attached to a support, comprising the steps of:
a) providing a discrete razor blade comprising tempered martensitic stainless steel, the discrete razor blade having a first side, a sharpened cutting edge, a back edge and a hardness at least 600 HV;
b) providing a groove in the first side along a length of the discrete razor blade by an application of laser energy to provide a weakened portion;
c) attaching the discrete razor blade to a support;
d) removing a portion of the discrete razor blade extending between the back edge and the weakened portion to result in a cutting edge portion of the discrete razor blade attached to the support, wherein the cutting edge portion extends from the cutting edge to the weakened portion;
wherein step c) is performed one of before and after step b); and
wherein the weakened portion includes untempered martensite.
2. The method of claim 1 , wherein, when step c) is performed before step b), the first side is cooled by an application of chilled gas after the application of laser energy.
3. The method of claim 2 , wherein the gas is air.
4. The method of claim 1 , wherein, when step c) is performed after step b), cooling of the discrete razor blade includes conduction to a chilled surface.
5. The method of claim 1 , wherein the application of laser energy is performed at a linear speed in a range about 200 to about 300 mm per second.
6. The method of claim 1 , wherein the groove has a width in the range about 0.035 to about 0.050 mm.
7. The method of claim 1 , wherein a proportion of retained austenite in the weakened portion is greater than a proportion of retained austenite of the discrete razor blade of step a).