US3318050A

US3318050A - Corn knife sharpener

Info

Publication number: US3318050A
Application number: US394661A
Authority: US
Inventors: Charles E Leckington
Original assignee: Individual
Current assignee: Individual
Priority date: 1964-09-08
Filing date: 1964-09-08
Publication date: 1967-05-09
Anticipated expiration: 1984-05-09

Description

May 9, 1967 Filed Sept. 8, 1964 C. E. LECKINGTON CORN KNIFE SHARPENER 2 Sheets-Sheet 1 I B fi 7 fi QM INVENTOR. K CHARLES E. LECKINGTON orney United States Patent 3,318,050 CORN KNIFE SHARPENER Charles E. Leckington, 1530 Springhill Road, Albany, Greg. 97321 Filed Sept. 8, 1964, Ser. No. 394,661 7 Claims. (Cl. 51-96) This invention relates to a machine for sharpening the knives used for removing kernels of corn from the cob.

Such knives are of complex shape having curved blades with bevelled helical cutting edges so that a plurality of the knives may be arranged to form a circular opening. When the circle of knives is rotated and ears of corn are moved through the opening one after another, the kernels are cut off the cobs.

Previous machines for sharpening the knives have been extremely complicated and expensive and so the knives are usually sharpened by hand on an ordinary abrasive wheel. This is a tedious process requiring considerable skill in order to achieve uniformity and accuracy and avoid excessive removal of metal.

The general object of the present invention is, therefore, to provide a relatively simple and inexpensive machine for sharpening corn knives uniformly and accurately, to provide a machine which will hone the knives faster while at the same time avoiding excessive loss of metal and burning of the blades and to provide a machine of the type described which requires relatively little skill to operate.

The present machine employs a new and improved knife holder for holding the knife at an oblique angle to an abrasive wheel and imparting a rotary motion to the knife during the honing operation. The knife holder is mounted on a combination of slides to adjust the position of the knife relative to the wheel in two different directions. A dressing tool is also included to keep the working surface on the wheel in true cylindrical shape.

The invention will be better understood and the foregoing and additional objects and advantages will become apparent from the following description of the preferred embodiment of the invention illustrated on the accompanying drawings. Various changes may be made, however, in the details of construction and arrangement of parts and certain features may be employed without others. All such modifications within the scope of the appended claims are included in the invention.

In the drawings:

FIGURE 1 is a top plan view of the machine;

FIGURE 2 is a front elevation view;

FIGURE 3 is a view taken on the line 3--3 of FIG- URE 1;

FIGURE 4 is a view taken on the line 44 of FIG- URE l FIGURE 5 is a view showing the convex side of the knife blade;

FIGURE 6 is a view showing the concave side of the knife blade; and

FIGURE 7 is a view taken on the line 7-7 of FIG- URE 6.

The machine comprises a base plate 10 having a horizontal bearing 11 for a circular abrasive wheel 12 which is driven at slow speed by belt pulley 13. The wheel has a cylindrical Working surface 14 of very fine texture for honing rather than grinding.

Mounted on the base is a guideway 15 for a lower slide 16. The slide is movable toward and away from the wheel in a direction parallel with the wheel axis by hand wheel 17 fixed on a threaded shaft 18. Longitudinal movement of the shaft is prevented by a thrust bearing 19 on base 10. The slide carries a nut 20 engaged with the threads on shaft 18.

Lower slide 16 carries a guideway for an upper slide 26 which moves toward and away from. the wheel in a direction transverse to the wheel axis. Slide 26 is freely movable by hand but its movement toward the wheel is limited by an abutment 27 on guide 25 which engages a stop screw 28 having threaded engagement with an apertured bracket 29 on the slide 26.

A support 30 is pivotally mounted on upper slide 26 by a single screw 31 as shown in FIGURE 3. Angular adjustment is maintained by a pair of setscrews 32 in bracket ears 33 on the slide on opposite sides of pivot screw 31. Support 34 carries an inclined bean'ng housing 35 which provides rotatable support for the knife holder 36.

The knife holder has a journal portion 35a rotatably mounted in a pair of hearings in the bearing housing 35. Mounted on this journal are a flat table portion 37 and an axial cylindrical extension 38 having on one side there of a knife blade positioning block 39 as shown in FIG- URE 3. Plate 37 is equipped with a stud 40 and a leaftype clamp spring 41 to hold the knife K. In sharpening a knife, the knife holder is rotated back and forth on the axis of journal 35a while the blade portion of the knife is pressed against the wheel by block 39 at a contact point C on one side of the wheel.

As shown in FIGURE 4, the under side of plate 37 is equipped with a depending lug 45 which projects between two ears 46 on the bearing housing 35. Stop screws 47 in these ears are adjustable to limit the angle of rotation of the knife holder.

As best shown in FIGURES 1 and 3, the upper slide 26 also has a projecting stud 50 carrying a dressing tool 51 to true the cylindrical working surface of the wheel 12. This tool is removed or turned to an inoperative position while knives are being sharpened.

It will be observed in FIGURE 2 that the rotational axis A of the knife holder 36 is inclined at a fixed angle as indicated at X with respect to the horizontal line H which is parallel with the wheel axis. Further, as indicated at Y in FIGURE 1, the axis A is seen to be disposed at a small angle later-ally from the line P which is parallel with the axis of the wheel. Angle Y is adjustable by setscrews 32. Thus, the axis A of the knife holder is inclined from the horizontal and it is also turned laterally slightly out of parallelism with a vertical plane through the axis of the wheel. The direction of axis A may also he described generally as oblique to all planes which contain the wheel axis. The reasons for these angles will be explained in relation to the shape of the knife K as illustrated in FIGURES 5 to 7.

Referring back to FIGURES l and 3, it will be seen that the knife has a flat base portion with a circular hole 61 and an arcuate end 62 containing a notch 63. This hole and notch are provided for accurately positioning the knife in a convention-a1 corn cutting machine. As seen in FIGURES 5 to 7, there is an upstanding blade portion 64 at the opposite end of base portion 60 having a helical cutting edge 65. For purposes of identification in FIG- URE 7, the low end of cutting edge 65 is indicated at 66 and the high end at 67.

This blade portion has a concave side 70in FIGURE 6 having a radius approximating the radius of a corn cob and a convex back side 71 shown in FIGURE 5. The

upper or outer end of the blade has a concave cylindrical bevel 72 on its concave side which intersects surface 70 on a sloping line 73. The convex back surface 71 is a cylindrical surface produced by honing, which surface is parallel to the inside cylindrical surface 7d. The surface 71 inter-sects the bevelled surface 72 on an inclined and slightly concave helical line which forms the cutting edge 65. This configuration of the cutting edge must be maintained in order to make the knife operate satisfactorily and considerable skill and care are required in sharpening such knives by hand.

The desired helix angle X in FIGURE 6 is maintained by inclining the rotational axis of the knife holder from the horizontal as indicated by the angle X in FIGURE 2. It is also desired to maintain the cylindrical honed back surface 71 at a small angle from a perpendicular with respect to base port-ion 60. This is represented by the angle Y in FIGURE 7 Where the line 80 is perpendicular to base 60. This is accomplished by turning bearing housing 35 on mounting screw 31 to a similar angle on slide 26 with respect to a vertical plane through the axis of the honing wheel as indicated by the angle Y in FIGURE 1.

Stated in more general terms without reference to horizontal and vertical directions in the preferred embodiment, the axis A of the knife holder is inclined from a direction radial to the wheel at the contact point C by an angle corresponding to the complement of the angle Y of the knife blade in FIGURE 7 and is inclined from a direction tangential to the contact point at an angle corresponding to the complement of the helix angle X in FIGURE 6.

In operation, the flat base 60 of the knife K is placed on table 37 with locating stud 40 in the hole 61. Then the knife is turned on the stud to engage its base under spring finger 41 and bring the concave surface 70 of upstanding cutting blade against locating block 39, as best shown in FIGURES l and 3. Lower slide 16 is adjusted to cause surface 71 to extend across the cylindrical working surface 14 of the wheel. Then the stop screw 28 is adjusted so that only the necessary amount of metal will be removed from surface 71 when upper slide 26 is moved to- Ward the wheel. Setscrews 32 are adjusted as described. Once these adjustments have been made for a single knife, they do not have to be altered for sharpening the rest of the knives of the set.

Upper slide 26 is advanced toward the wheel as table 37 is grasped and rotated back and forth through the angle permitted by stop screws 47. Locating block 39 then operates as a pressure member to press the surface 71 against the wheel and prevent deflection of the blade. Metal will be removed from the surface 71 until stop screw 28 engages abutment 27 whereupon the sharpening operation is completed and the blade may be removed and replaced by another blade of the set. In replacing the blades on table 37, the slide 26 is retracted forward to provide a wide space between block 39 and the wheel.

In a corn cutting machine, a plurality of the knives K are mounted on a rotating annular plate or flange with the blade portions 64 extending axially and forming a stepped circle of cutting edges 65. As ears of corn are fed axially into this circle, the kernels are cut off and the cob passes on through. When the knives become dull, the whole set must be sharpened. When the first knife has been placed in the sharpening machine and the adjustments made at 17, 28 and 32 as described, the knives of the set may be sharpened one after another in rapid succession without any further adjustment.

This assures that all the knives will be identical, with the proper shape of cutting edge, and that the operator will not hone some of the knives more than others. Stop screw 28 limits the honing on every knife at the same point. Each knife is assured of being at proper position in the knife holder because the blade portion 64 bears directly against the positioning block 39. Block 39 and stud 40 hold the knife in the same position relative to axis A that the knife occupies in relation to the axis of the rotary knife holder in the corn cutting machine. Thus, the rather delicate sharpening operation may be performed accurately and quickly without burning and without requiring great skill on the part of the operator.

Having now described my invention and in what manner the same may be used, what I claim as new and desire to protect by Letters Patent is:

l. A corn knife sharpening machine comprising a honing wheel mounted for rotation on a horizontal axis and having a cylindrical working surface, a horizontal slide movable transversely of said axis toward and away from said wheel, a knife holder mounted for rotational movement on said slide about an axis which is inclined vertically from horizontal and inclined laterally toward said wheel axis, means for clamping a knife on said holder, and a positioning block on said holder arranged to engage a portion of the knife blade directly behind the blade surface to be ground and press said blade surface against said wheel surface when said slide is moved toward said wheel.

2. A corn knife sharpening machine comprising a base plate, a honing wheel mounted on said base plate for rotation on a horizontal axis and having a cylindrical working surface, a horizontal slide on said base plate movable longitudinally of said axis toward and away from said wheel, a horizontal slide mounted on said first slide for movement transversely of said wheel axis toward and away from said wheel, a knife holder mounted on said last slide to present a knife blade to a predetermined point of contact on said working surface on one side of said wheel, said knife holder being mounted for rotation on an axis which is inclined vertically from horizontal and inclined laterally toward said wheel axis, and means for clamping a knife on said holder.

3. A machine as defined in claim 2, including a dressing tool for the honing wheel mounted on said last slide.

4. A machine for sharpening a corn knife having a fiat base portion with a cylindrically curved blade portion outstanding from said base portion at a small angle from perpendicular to said base portion, said blade portion having a helical cutting edge at a predetermined helix angle relative to said base portion; said machine comprising a honing wheel having a cylindrical working surface, a knife holder arranged to present said blade portion to a predetermined point of contact on said working surface, said knife holder being mounted for rotation on an axis of rotation inclined from a direction radial to the wheel at said point of contact at an angle corresponding to the complement of said small angle of said knife blade and inclined from a direction tangentialto said point of contact at an angle corresponding to the complement of said helix angle.

5. A machine for sharpening a corn knife having a flat base portion with a cylindrically curved blade portion outstanding from said base portion at a small angle from perpendicular to said base portion, said blade portion having a helical cutting edge at a predetermined helix angle relative to said base portion; said machine com prising base plate, a honing wheel mounted on said base plate for rotation on a horizontal axis and having a cylindrical working surface, a horizontal slide mounted on said base plate for movement toward and away from said wheel in a direction parallel with the axis of the wheel, a horizontal slide mounted on said first slide for movement toward and away from the wheel in a direction transversely of said wheel axis, a knife holder mounted on said last slide and arranged to present said blade portion to a predetermined point of contact on said working surface, said knife holder being mounted for rotation on an axis inclined from horizontal at an angle corresponding to said helix angle and inclined laterally toward said wheel axis at an angle corresponding to said small angle.

6. A corn knife sharpening machine as defined in claim 1, said knife holder comprising a supporting hearing on said inclined axis, a journal mounted for rotation in said bearing, a flat table plate on said journal extending perpendicular to said inclined axis, a knife locating stud on said plate, said means for clamping a knife on said holder comprising a spring finger for clamping the knife against said plate, said positioning block being mounted on said plate at a distance from said inclined axis for pressing an upstanding blade portion of the knife against said honing wheel.

7. In a machine as defined in claim 6, a pivotally mounted support for said bearing, and setscrews engaging said support at a distance from the pivotal axis of said support to adjust the angular position of said support.

References Cited by the Examiner UNITED STATES PATENTS 10 ROBERT c. RIORDON, Primary Examiner.

D. G. KELLY, Assistant Examiner.

Claims

1. A CORN KNIFE SHARPENING MACHINE COMPRISING A HONING WHEEL MOUNTED FOR ROTATION ON A HORIZONTAL AXIS AND HAVING A CYLINDRICAL WORKING SURFACE, A HORIZONTAL SLIDE MOVABLE TRANSVERSELY OF SAID AXIS TOWARD AND AWAY FROM SAID WHEEL, A KNIFE HOLDER MOUNTED FOR ROTATIONAL MOVEMENT ON SAID SLIDE ABOUT AN AXIS WHICH IS INCLINED VERTICALLY FROM HORIZONTAL AND INCLINED LATERALLY TOWARD SAID WHEEL AXIS, MEANS FOR CLAMPING A KNIFE ON SAID HOLDER, AND A POSITIONING BLOCK ON SAID HOLDER ARRANGED TO ENGAGE A PORTION OF THE KNIFE BLADE DIRECTLY BEHIND THE BLADE SURFACE TO BE GROUND AND PRESS SAID BLADE SURFACE AGAINST SAID WHEEL SURFACE WHEN SAID SLIDE IS MOVED TOWARD SAID WHEEL.