US2762175A

US2762175A - Shear grinding

Info

Publication number: US2762175A
Application number: US259792A
Authority: US
Inventors: John F Kramer
Original assignee: Individual
Current assignee: Individual
Priority date: 1951-12-04
Filing date: 1951-12-04
Publication date: 1956-09-11
Anticipated expiration: 1973-09-11

Description

p 1956 J. F. KRAMER 2,762,175

SHEAR GRINDING Filed Dec. 4, 1951 2 Sheets-Sheet 1 IN VEN TOR. JOHN E KRAMER BY E/CHE); wArrs, EDGE/ETO/Vl MAYNENNY 477' ENEKS' United States Patent SHEAR GRINDING John F. Kramer, Bellevue, Ohio Application December 4, 1951, Serial No. 259,792 3 Claims. (Cl. 51-285) This invention relates to grinding machines for scissors and other cutlery, and is particularly adapted to grinding the blade shape usually found on barber shears.

In shear grinding technique, there are three features to be considered when obtaining the optimum contour for a scissor blade. The blade from the pivot to the extreme tip is generally in the form of an are which, when the blades are assembled in abutting relation, tends to make one blade oppose the inner surface of the other. Secondly, the surface of the opposed sides of the blades are hollow ground to render the blades self-sharpening as the scissor is used. Thirdly, the cutting edge of the blade is curved longitudinally and beveled laterally to form a cutting edge at the side of the blade which is in contact with the opposed blade.

Factory fabrication and sharpening of the blade is done by a machine which accurately forms the abovementioned portions to accurate standards. However, the sharpening of the blades of the scissors by the user generally done in a hit-or-rniss fashion by manually hold ing the blade against a grinding wheel. Accordingly, the individual doing the sharpening must rely on sense of touch to determine the angle at which the edge of the blade is applied to the wheel to obtain the proper edge. The inadequacies of this method of sharpening are wel known, s nce it is impossible to duplicate the original contour as formed during the manufacturing process.

Accordingly, it is an object of this invention to provide an apparatus which will sharpen the scissors and return the cutting edge to the original condition.

Another object of this invention is to provide a grinding apparatus having mechanical structure for holding the scissor blades in various positions during the grinding operation.

A further object of this invention is to provide a grinding wheel having the surfaces thereof contoured to theshape of'the finished blade.

A still further object or" this invention is to provide holding means'for the scissor blades which is arranged to hold the blade in alternate positions in respect to the contoured surface of the grinding Wheel, the point of the blade being near the center of rotation of the wheel and the portion of the blade having the largest crosssection being at the periphery of the wheel where the maximum grinding eflfect is obtained.

' A further important object of this invention is to provide an apparatus for grinding scissor blades which is portable and may be used with ease by the ordinary individual to recondition the cutting edges of the scissors in an economical manner without skill or practice.

Other objects and advantages more or less ancillary to the foregoing, and the manner which all the various objects are realized, will appear in the following description, which, considered in connection with the accompanying drawings, sets forth the preferred embodiment of the invention.

In the drawings:

Fig. l is a perspective view of the scissor grinder mechanism;

Fig. 2 is an end view of the clamp bracket;

Fig. 3 is a side view of the holding clamp;

Fig. 4 is a sectional view of the grinding wheel with the convex surface uppermost; and

Fig. 5 is a sectional view showing the concave surface uppermost.

Referring first to Fig. l, the numeral 10 designates 'a grinding wheel mounted on a spindle 12 for rotation relative to a frame 14. The wheel is retained on the spindle 12 by a nut 16, threadably engaged therewith. A washer 13 is located between the nut 16 and the wheel 10 for reducing the friction between the wheel and the nut for tightening purposes. A sleeve 2% on the spindle 12 spaces the grinding wheel 1 away from the frame 14 as required to position the wheel in relative to the scissor blade clamping mechanisi As shown in Fig. 4, the wheel it} has a convex surface 22 for grinding a contour on the side of the scissor blade 24. A concave surface 26 is formed on the side of the wheel opposite to the convex surface 22 for grinding the curved contour of the edge of the blade 24] The shape of the

surfaces

22 and 26 is determined by the optimum shape of the scissor blade for best cutting operation. When the blades are pivoted together in abutting relationship, the longitudinal curvature holds the points of the blades together as the cutting takes place. This curvature amounts to approximately ta of an inch in the length of the scissor blade. The curvature of the surface 26 is substantially greater than that of the surface 22, as required to form the cutting edge from the full width of the blade to the cutting point.

A blade holding clamp mechanism is mounted for vertical movement on a square post 28. The post 28 is rigidly affixed to a base 30 which is slidably mounted to the frame 14 by a bar 32 which is formed for dovetail engagement with the complementary slot 3% in the base 3%. The dovetail bar 32 allows the base 39 and post 28, affixed thereto, to be moved laterally toward and away from the grinding wheel in.

A pair of sleeves 36 are mounted in slidable engagement with the post 23 in spaced-apartrelationship. A pair of springs 38 are placed on the post 23 for resiliently supporting the sleeves 36 against vertical movement. The lower spring is restrained by the base as, and the upper spring 38 is held against movement at one end by the washer 40 affixed-to the end of the post 38.

A face plate 42, having its'face parallel to the post 2% is supported by a pair of struts 44- intermediate the plate 42 and the sleeve 36. A hinge plate 46 is pivoted to the center of the plate 42 for rotation therearound and is held in position by friction produced bya clam ing bolt 48 which passes through an arcuate slot 58 in the plate .2. Plate 46, therefore, can be pos'itio'nedat various angles relative to vertical by loosening the bolt 48 and rotating the same about the pivot.

Clamp 52 is swingably mounted on the plate 46 by a hinge bolt 54, having a wing nut 56 for tightening the joint, for binding the hinge joint and preventing relative motion of the clamp 52 and the plate 45. V

The clamp 52 has a pair of clamping at each side thereof for engaging'the handle'pcrticn 6%; of the scissor blade 24. A pair of bolts 62, having wing nuts 64 therein, compress the handle as Ll. n the fingers 58 for releaseablyholding the blade 2-iduring the sharpening operation.

In-operation, the grinding wheel is driven by a prime mover (not shown herein) at some suitable grinding speed. The scissor blade 24 is placed in the clamp 52 with the handle portion 60 rigidly clamped by the fingers ing along the blade to the v 3 58. The clamp 52 is horizontal to hold the blade along the radius of the wheel and perpendicular to the center of rotation thereof. The spherical convex surface 22 hollow grinds the side of the blade 24 and produces the curvature longitudinally in one operation. To sharpen the edge of the blade, the clamping mechanism is moved away. from the wheel on bar 42 until the end of the blade 24 will clear the wheel 10. The stone is then inverted with the concave surface 26 of the wheel uppermost.

' The sleeve 20 is removed from the spindle and placed above the stone, thereby lowering the plane of rotation by a distance equal to the length of the spacer.

The locking bolt 54 is then loosened by rotating the thumb nut 56, and the clamp 52 is swung downuntil the blade is disposed at an angle approximately five degrees to vertical and in approximate engagement with the grinding wheel 10, as the blade, 24 engages the wheel 10, as shown in Fig. 5, for producing the longitudinal curved edge'and the bevel at the edge in one grinding operation. The'blade 24 may, then be removed from the clamp 52- in its readyto-u se condition.

It is noted that the springs 38 bias the clamping mechanism into a central position from which the clamp with the'scissor blade 24, mounted therein, can be moved toward and away from the wheel 10 against the force of the springs.

The blade 24 engages the wheel 10 with the'point near the center of rotation of the, wheel 10 and the portion of the blade having the largest cross section at the periphery of the wheel 10. By applying the blade to the wheel 10 in this manner, the maximum grinding effect is obtained at the thickest part of the blade, thus producing uniform sharpening along the length of the blade 24. Further, the heat generated in the grinding process is carried away by the part ofthe blade having the heavier section, thus preventing burning of the blade material in the region of the periphery of the wheel 10 where the grinding speeds are high. Applying the blade 24 to the wheel 10 in this manner, therefore, facilitates uniform sharpening throughout nates'possible damage by over-heating the material of the blade 24.

An alternate mode of operation results from grinding the side of the blade 24 with the wheel in the position shown in Fig. 4. After this operation, the blade is placed 7 beneath the wheel 10 with the cutting edge of the blade uppermost toward the lower side 26 of the wheel 10, as shown in Fig. 4. The blade 24 is then sharpened along the edge, the entire sharpening process being achieved without adjusting the wheel.

- Although the foregoing description is necessarily of a detailed character, in order that the invention may be completely set forth, it is to be understood that the specific terminology is not intended to be restrictive or confining, and that various rearrangements ofparts and modifications of detail may be resorted to without shown in Fig. 5. In this position, 7

the length of the blade and elimideparting from the scope or SPIIll'. of the invention as' herein claimed.

What is claimed is:

1. A process of grinding an elongated tapered metallic scissor bladehaving a cross-section diminishing toward the free end and having a surface to be ground extendfree end thereof, comprising rotating about its central axis a grinding wheel having a side grinding surface with a radius greater than the length of said surface to be ground, said side grinding surface being a non-planar surface of revolution and pressing the scissor blade against said side grinding surface with the blade extending in a generally radial direction with respect to said grinding wheel and with the said side grinding surface the said side surface to be ground engaging said side grinding surface and the free end of the blade engaging said side grinding surface closer to the central axis of said wheel than the remainder of said blade whereby the linear speed 'of said grinding surface with respect to said surface to be ground is least at the free end of the blade and increases progressively with respect to the portions blade of increasing cross section'.

2. A process of grinding an elongated tapered metallic scissor blade having a cross-section diminishing toward the free end and having a surface'to be ground'extending along the the free end thereof, comprising rotating about its central axis a grinding Wheel having a side grinding surface with a radius greater than the length 'of said surface to be ground, said side grinding surface being a non-planar surface of revolution and pressing the 'scissorblade against said side grinding surface with the blade extending'in a generally radial direction withrrespect to. said grinding wheel and'with the surface. to be ground engaging said side grinding surface and the free end of the 'blade engaging said side grinding surface closer to the central axis of said wheel than the remainder of said blade whereby the linear speed ofsaid side grinding surface with respect to said surface to be groundis least at the free end of the blade and'increases progressively with respect to the portions of said blade 'of increasing crosssection. W V V 3. A process of grinding an, elongated tapered metallic scissor blade having a side surface intersecting an edge surface to form a cutting edge, the side surface of said blade diminishing in width toward the free end of the blade and said blade also. diminishing in thickness toward the free end thereof comprising rotating about its central axis a grinding wheel having a convex side grinding surface the side surface of said blade, said side grinding surface having a convex curvature in a radial direction and also a convex curvature circumferentially, pressing against the surface of said blade with said blade extending in a generally radial direction with its free end'engaging said side grinding surface closer to the central axis of said. grinding wheel than the remainder of said blade, whereby the linear speed of said side grinding surface Withrespect to said least at the free end of the side surface of said blade is References Cited in the file of this patent UNITED STATES IVBATENTS" 7 60,922 Merriman Jan. 1, 1867 526,571 Gosling 'Sept. 25, 1894 543,458 Berry July 30, 1895 642,180 Twist Jan. 30, 1900 774,612 Stead Nov. 8, 1904 936,935 Perrine Oct. 12, 1909 961,554 Sweet June 14, 1910 1,005,808 Bunnell Oct. 17. 1911' 1,016,072 Johnson ']an. 30, 1912 1,556,432 Fleming Oct.'6, 1925 1,811,069 Webb 2 June 23, 1931 2,257,354 Strezoff Sept. 30, 1941 2,311,582 Strezoif Feb. 16, 1943 2,532,512 Paget Dec. 5, 1950 2,578,309 Kroczek Dec. 11, 1951 FOREIGN PATENTS 575,823 Germany May 3,1933 588,405 Great Britain May 21, 1947 of said 7 blade ali'ifldiminishing in width toward with a radius exceeding the length of