US2749678A - Knife sharpener - Google Patents

Description

United States Patent KNIFE SHARPENER Charles R. Jahn, Chicago, Ill.

Application September 9, 1954, Serial No. 454,939

6 Claims. (Cl. 51-181) This invention relates to an improved knife sharpener.

One principal object of the invention is to provide an improved knife sharpener capable of being used for sharpening and honing the edge of a knife in successive operations which are easily carried out.

A further object is to provide a knife sharpener having means for maintaining the sharpening and honing elements in optimum engagement.

It is another object of the invention to provide an improved knife sharpener arranged to compensate for wear in the sharpening and honing elements.

A further object is to provide an improved knife sharpener having means whereby fresh surfaces of the sharpening elements may be brought into play to compensate for wear.

Another object of the invention is to provide an improved knife sharpener which is simple to use, attractive in appearance and low in cost.

Further objects and advantages of the invention will appear from the following description, taken with the accompanying drawings, in which:

Figure 1 is an elevational view of an exemplary knife sharpener constituting a purely illustrative embodiment of the invention;

Fig. 2 is a plan view of the knife sharpener of Fig. 1;

Fig. 3 is a longitudinal sectional view taken generally along a line 33 in Fig. 2;

Fig. 4 is an enlarged fragmentary sectional view taken generally along a line 4-4 in Fig. 1;

Fig. 5 is a fragmentary elevational view taken as indicated by a line 5-5 in Fig. 2;

Fig. 6 is a perspective view of a pair of abrasive sharpening wheels employed in the knife sharpener;

Fig. 7 is a perspective view of a pair of honing balls embodied in the sharpener;

Fig. 8 is a perspective view of a spring mechanism for biasing the wheels and balls; and v v Fig. 9 is a fragmentary sectional view illustrating a modified arrangement of the honing balls.

If the drawings are considered in greater detail, they will be seen to illustrate a knife sharpener 10 adapted to sharpen and hone the edge of a knife. The illustrated sharpener comprises a body 11 having one end formed into a handle 12 adapted to be gripped by the hand of a user. Feet 13 and 14 in the form of rubber or rubberlike grommets are mounted on the underside of the body 11 to support the knife sharpener on a table .or other supporting surface. The grommets 13 and 14are seated in apertures 15 and 16 formed in lower wall elements 17 and 18 of the body 11. The body 11 preferably is formed from a resinous plastic material by a molding operation and hence is shown as including a pair of half shells 19 and 20 joined by cement or by the illustrated screw fasteners 21. The body 11 is formed with an enlarged head 22 for supporting the sharpening and honing elements of the sharpener.

in order to provide for the sharpening of a knife, two

engageable abrasive wheels or stones 23 and 24 are mounted in the head end 22 of the body 11. The sharpening wheels 23 and 24 may be made of any suitable material, such as sintered aluminum oxide, for example. It will be seen that the wheels 23 and 24 are cylindrical or roller-shaped in form.

In the illustrated construction, the wheels 23 and 24 are received in recesses 25 formed in the opposed half shell members 19 and 20. Shafts 26 and 27 extend axially through the wheels 23 and 24. The shaft 26 for the first wheel 23 is rotatably supported in bearing openings 28 and 29 formed in the half shells 19 and 20. To provide for lateral translation as well as rotation of the second wheel 24, the shaft 27 is received in elongated slots or bearing openings 30 and 31 formed in the half shells 19 and 20. With this construction, the wheel 24 is movable toward and away from the wheel 23. However, the range of movement of the wheel 24 is limited by the recesses 25 so as to prevent a knife from passing between the wheels 23 and 24. It will be seen that the recesses 25 are formed with cylindrically curved end portions 32 and 33 having a loose fit with the peripheries of the wheels 23 and 24.

In order to provide for rotary adjustment of the wheels 23 and 24, a kerf 34 or other tool engaging element is formed in one end of at least one of the shafts 26 and 27. In this instance, both of the shafts 26 and 27 are formed with the kerfs 34. It will be understood that a screw driver or other suitable tool may be engaged with either of the kerfs 34 to rotate the wheels 23 and 24 and thereby bring new sharpening surfaces into play. Rotating either of the wheel shafts 26 and 27 will tend to rotate both wheels because of the frictional engagement between the wheels. The bearing openings 28 and 30 in the half shell 19 are in the form of apertures extending through the wall of the half shell so as to afford access to the kerfs 34. In the other half shell 20 the bearing openings 29 and 31 may be in the form of recesses.

For the purpose of honing the edge of a knife, the knife sharpener 10 is equipped with first and second engageable metal balls 36 and 37 received in opposed recesses 33 formed in the half shells 19 and 20. It will be seen that the recesses 38 are provided with spherically curved end portions 39 and 40 which limit spreading movement of the balls 36 and 37 so that a knife will be prevented from passing completely between the balls.

A spring 41 or other resilient element is provided to bias the sharpening wheels 23 and 24 and the honing balls 36 and 37 together. In this instance, the resilient element 41 takes the form of a generally helical compression spring acting between arms 42 and 43 of a generally U- shaped member 44. The upper end of the arm 42 is formed into a cylindrically curved portion 45 which engages the periphery of the sharpening wheel 24 and urges the wheel against the other wheel 23. The upper end of the arm 43 is provided with a portion 46 which engages the ball 37 and urges it against the ball 36. In the illustrated construction, dimples 47 and 48 are formed in the arms 42 and 43 to retain the opposite ends of the compression spring 41.

In order to admit a knife to the crotches between the wheels 23 and 24 and the balls 36 and 37, V-shaped notches 49 and 50 are formed in the body 11 opposite the wheels and balls to reduce friction between the abrasive wheels 23 and 24 and the body 11 of the sharpener, and thereby facilitate rotary adjustment of the wheels, the body 11 is formed with bosses 51, 52, 53, and 54 around the bearing openings 28, 29, 30 and 31. These bosses provide clearance between the body 11 and the major portion of the end area of the abrasive wheels 23 and 24.

In use, the knife sharpener is gripped in one hand of the user and preferably is. held with the feet 13 and 14 against a table or some other supporting surface. The rubber feet prevent the sharpener from slipping along the table when the sharpener is in use. I

A knife may be sharpened by inserting the cutting edge of the knife through the V-shaped notch 49 and into the crotch between the abrasive sharpening wheels 23 and 24. The knife is drawn longitudinally along the crotch to sharpen the cutting edge. During the sharpening operation, the spring 41 holds the abrasiye'wheels 23 and24 together. If heavy pressure is applied to the knife, the wheels may separate slightly, but the amount of separation is limited by the extent of the recesses 32 so that the knife will not pass between the wheels and drag on the plastic body 12,

The knife may be honed by inserting its cutting edge into the notch 59 and drawing the lunfe longitudinally along the crotch between the honing balls 36 and 37. During this operation, the spring 41 biases the ball 37 toward the ball 36. Normally the balls are held in engagement during the honing operation. Even if considerable pressure is applied to the knife, the recesses 33 in the body 11 prevent any substantial separation of the balls. Accordingly, the knife cannot be pushed between the balls so as to come into engagement with the body 11.

After considerable use, the abrasive sharpening wheels 23 may be worn fiat in the sharpening zone provided by the crotch between the wheels. However, new sharpening surfaces may be brought into play simply by inserting a screw driver or other suitable tool into the kerfs 34 and rotating the wheels 23 and 24. The bosses 51, 52, S3, and 54 facilitate such rotation by reducing the friction between the wheels and the body 11.

The knife sharpener ll) may be manufactured at an extremely low cost and, hence, may be marketed on a large scale or even given away as a premium item. The sharpener is not only effective in carrying out its' intended purpose, but also is convenient in use and attractive in appearance.

Fig. 9 illustrates a modified construction in which the balls 36 and 37 are received in a pair of recesses 38a formed in the half shell elements 19 and of the body 11. In order to maintain the balls in engagement when a knife is pushed downwardly into the crotch between the balls, the recesses 38a are formed with downwardly tapering or converging end surfaces 39a and 49a. When downward pressure is applied to the balls 36 and 37 the converging end surfaces 39a and 40a tend to wedge the balls toward each other and thereby maintain the balls in intimate engagement. In this way, the balls are prevented from spreading substantially under the pressure of a knife thrust downwardly into the crotch between the balls. With this modified construction, it is not necessary to utilize a spring or other resilient element to bias the honing balls into engagement. Accordingly, the right hand leg 43 and the lower portion of the member 44- of the construction shown in Fig. 3' are omitted in the modified construction of Fig. 9, leaving only the left hand leg, designated 42a, having a curved portion 45a engaging the sharpening stone 24. The spring 41 is seated in opposed recesses 41a formed in the half shells 19 and 20. The recesses 41a prevent lateral displacement of the spring 41 and eliminate any need for a dimple or other spring supporting element on the member 42a.

Various modifications, alternative constructions and equivalents may be employed without departing from the true spirit and scope of the invention as exemplified in the foregoing description and defined in the following claims.

I claim:

1. A knife sharpener, comprising abody including a pair of half shells joined together, said body having one end portion. formed into a handle, a pair of. rubber-like feet mounted on said body adjacent its opposite ends for engaging a supporting surface, a pair of engageable generally cylindrical abrasive wheels, said half shells having generally cylindrically curved recesses receiving said wheels, said wheels having shafts extending therethrough, one of said half shells haying apair of apertures for supporting said shafts at one end thereof, at least one of said safts at one end thereof having a kerf formed therein for adjusting. the angular positions of said wheels, and the other of said half shells having a pair of openings for supporting the opposite ends of said shafts, one of said apertures and one of. said openings being elongated to provide for lateral movement of one of said wheels toward and away from the other of said wheels, 21 pair of engageable metallic honing balls, said half shells having spherically curved recesses receiving said balls, said body having a pair of notches formed therein for admitting a knife to thecrotches between said wheels and said balls, said cylindrically curved and spherically curved recesses limiting spreading movement of said wheels and said balls to prevent a knife from passing fully therebetween, a generally U-shaped member having a first leg engaging one of said wheels and a second leg engaging one of said balls, and a helical compression spring disposed between said legs for biasing said one wheel and said one ball against said other wheel and said other ball.

2. A knife sharpener, comprising a handle including a pair of half shells, first and second engageable abrasive sharpening wheels having first and second shafts extending therethrough, first bearing means in said half shells supporting said first shaft for rotation, second bearing means insaid half shells supporting said second shaft for rotation and lateral movement toward and away from said first shaft, first and second engageable honing balls arranged in line with said wheels, said half shells having spherically curved recesses supporting said balls, said recesses supporting said second ball for limited lateral movement toward and from said first ball, and resilient means acting between said second sharpening wheel and said second ball for biasing said second wheel against said first wheel and biasing said second ball against said first ball.

3'. A knife sharpener, comprising a supporting body, first and second abrasive wheels, means for rotatably mounting said first wheel in said body, means mounting said second Wheel in said body for rotation and lateral movement toward and away from said first wheel, first and second honing bails arranged in line with said Wheels, means rotatably mounting said first ball in said body, means mounting said second ball in said body for rotation and lateral movement toward and away from said first ball, and resilient means acting between said second wheel and said second ball for biasing said second Wheel against said first wheel while biasing said second ball against said first ball.

4. A knife sharpener, comprising a supporting body, first and second abrasive wheels with engageable pcripheral surfaces, means mounting said wheels in said body for rotary adjustment and supporting said second wheel for limited movement toward and away from said first wheel, resilient means biasing said second wheel against said first wheel, and means on at least one of said wheels defining a screw driver slot for effecting rotary adjustment of said wheels.

5; A knife sharpener, comprising a supporting body, first and second abrasive wheels with engageable peripheral surfaces, means mounting said wheels in said body for rotary adjustment and supporting said second wheel for limited movement toward and away from said first wheel, resilient means biasing said second wheel against said first wheel, and means on at least one of said wheels defining a tool receiving formation for efiecting rotary adjustment of said wheels.

6. A knife sharpener, comprising a supporting body, first and second abrasive wheels, means for rotatably mounting said first wheel in said body, means mounting said second wheel in said body for rotation and lateral movement toward and away from said first wheel, first and second honing balls arranged in line with said wheels, means rotatably mounting said first ball in said body, means mounting said second ball in said body for rotation and lateral movement toward and away from said first ball, resilient means acting between said second wheel and said second ball for biasing said second Wheel against said first wheel while biasing said second ball against said first ball, and means on at least one of said wheels defining a screw driver receiving formation for elfecting rotary adjustment of said wheels, said body having an opening for admitting a screw driver to said formation.

References Cited in the file of this patent UNITED STATES PATENTS 1,353,485 McGall Sept. 21, 1920 1,463,653 Loomis July 31, 1923 1,612,323 Statts-Oels Dec. 28, 1926 FOREIGN PATENTS 131,130 Great Britain Aug. 12, 1919 206,251 Switzerland July 31, 1939 681,766 Great Britain Oct. 29, 1952

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