Krect Spiral Curve
FiledFriday, 15th December 1933
PublishedTuesday, 31st December 1935
InventorChester Arthur Gratiot
Parts not referenced in the text: None
Parts not referenced in the images: None
My invention relates to safety-razors of the type in which a thin double-edged blade is clamped between a guardpiece and cap constituting forming members by means of which the blade is attached to a handle and strained to alter its normal mechanical properties and adjust the disposition of the cutting edges with reference to the said guard-piece and handle.
The principal object of my invention is the provision of a safety-razor having improved properties relating to facility of use in shaving, efficacy of operation, and endurance of the shaving edges.
A second object is the provision of certain adjustments inherent in the device facilitating cleaning.
A third object is the provision of unique and efficient clamping means facilitating assembly and separation of the several parts for washing, drying, and sterilizing.
Other objects and advantages of my invention will be apparent in the following discourse wherein the significance of the reference characters in the accompanying drawing, details of construction of a typical safety-razor of my invention and the particular advantages thereof are explained.
My invention contemplates for the accomplishment of the objects set forth:
An unusually rigid convex cutting edge disposed through its length at a variety of angles to the axis of the handle with respect to any aspect thereof so that a selection of angles between the skin and the blade and between the cutting edge and the direction of motion of the razor may be available upon the shifting of the razor laterally, and, conversely, so that by shifting the razor laterally to effect an oblique stroke the cutting angle of the successively contacting portions of the convex edge may be maintained at a constant value when the motion of the razor is pivotal about the wrist of the user as is natural;
A manner of adjustment of the razor without disconnecting the pieces providing for the separation of the cap, guard, and blade to permit the passage therebetween of water, sterilizing liquids or gases, and air;
Means providing for the rapid assembly of the razor without unnecessary movements; and
Means providing for the straining of the cutting edges in tensile stress to enhance the rigidity thereof.
The razor is composed of a cap
The curvatures of the concave surface of the cap
The blade is double-edged and formed with a longitudinal slot
The convex surface of the guard
To assemble the razor, the cap
In this adjustment it is to be noticed that the guard, blade and cap are separated by appreciable distances. This relationship of these parts provides for easy washing of the razor which is securely held by the coaction of the strains in the blade and the hook
To adjust the razor for shaving the handle is raised to the perpendicular position as illustrated in
In addition to those advantages and special properties of a razor of the general form of the oblique cylindrical segment as described in my application for Letters Patent of the United States for Safety-razors, filed January 17, 1933, Serial No. 652,133, the present invention provides these further unique advantages and properties:
My present invention provides for the critical equality and uniformity of relationship of the cutting edges of the blade with the edges of the guard. It will be apparent from a study of the form of the blade which is characterized by a longitudinal slot parallel with parallel cutting edges, and a study of the disposition of the plate
The inclined surfaces
Reference to my previous invention before referred to will disclose that reliance was had solely upon bending stresses in the blade to dispose the cutting edges thereof at the proper position. This is in contrast to the present invention wherein another force is provided for which effects the disposition of the cutting edges as just described. In the present invention I have provided that the cutting edges of the blade shall also be subject to a tensile stress to improve the rigidity of the edges as well as the positioning thereof with reference to the guard edges.
Tensioning of cutting edges is a practice acknowledged by saw-makers to improve the rigidity of the armed edges and applies with equal propriety and effect in razors. The means I have chosen to produce this effect reside in the prolate spheroidal forms described to which a normally flat blade is strained. The effects of such straining are illustrated in the diagram
Each half of the blade assumes a position tending toward those illustrated in this figure. The slot becomes wider in the middle and the blade at the slot-margin is compressed and the cutting edges proportionately strained in tension. The cutting edges are thus used with the utmost advantage.
Other advantages of great practical utility are obvious from a study of the drawing.
Having described my invention what I claim is:
1. A safety-razor in which a normally flat flexible blade having parallel cutting edges and a central longitudinal slot parallel therewith is clamped between a cap and a guard having blade-contacting surfaces conforming to an oblique segment of the surface of a prolate spheroid, wherein blade-holding means engaging said longitudinal slot in said blade incline toward corners of said cap and guard characterized by curvatures of least radii.
2. A safety-razor having a cap and guard with blade clamping surfaces conforming to a segment of the surface of a prolate spheroid, a hook attached to said cap and extending through said guard, and a handle attachable to said hook to secure the whole together.
3. A safety-razor having a cap and guard with blade-clamping surfaces conforming to an oblique segment of the surface of a prolate spheroid, a hook attached to said cap and extending through said guard, and a handle attachable to said hook to secure the whole together.
4. A safety-razor having a cap and guard with blade clamping surfaces conforming substantially to oblique segments of the surfaces of prolate spheroids» a normally flat flexible blade clamped between said cap and guard, a hook attached to said cap and extending through said guard and said blade, and a handle attachable to said hook to secure the whole together.
5. A safety-razor comprising, a normally flat flexible blade and a cap and a guard between which said blade is clamped, said guard and said cap having blade-contacting surfaces conforming substantially to complementary oblique surface-segments of prolate spheroids.
6. A safety-razor comprising, a normally flat flexible blade having parallel cutting edges and a longitudinal slot therebetween, a cap and a guard between which said blade is clamped fitted with means to engage said slot and align said blade, said cap and said guard having blade-contacting surfaces conforming substantially to complementary oblique surface-segments of prolate spheroids.
Chester A. Gratiot.