US2986850A

US2986850A - Cutlery sharpening machine

Info

Publication number: US2986850A
Application number: US671524A
Authority: US
Inventors: William N Batchelder
Original assignee: Individual
Current assignee: Individual
Priority date: 1957-07-12
Filing date: 1957-07-12
Publication date: 1961-06-06
Anticipated expiration: 1978-06-06

Description

June 6, 1961 w. N. BATCHELDER CUTLERY SHARPENING MACHINE 5 Sheets-Sheet 1 Filed July 12, 1957 INVENTOR.

WILLIAM N. BATCHELDER ATTORNEYS June 6, 1961 w. N. BATCHELDER 2,986,850

CUTLERY SHARPENING MACHINE Filed July 12, 1957 s Sheets-Sheet 2 INVENTOR.

WILLIAM N. BATCHELDER WWW M ATTORNEYS June 6, 1961 w. N. BATCHELDER 2,986,850

CUTLERY SHARPENING MACHINE Filed July 12, 1957 5 Sheets-Sheet 3 INVENTOR. WILLIAM N. BATCHELDER ORNEYS June 1961 w. N. BATCHELDER CUTLERY SHARPENING MACHINE 5 Sheets-Sheet 4 Filed July 12, 1957 rrm INVENTOR. WILLIAM N. BATCHELDER ATTORNEYS J1me 1961 w. N. BATCHELDER 2,986,850

CUTLERY SHARPENING MACHINE WILLIAM N. BATCHELDER ATTORNEYS Unite States Patent 6 2,986,850 CUTLERY SHARPENING MACHINE William N. Batchelder, 158 15th Ave., San Francisco, Calif. Filed July 12,1957, Ser. No. 671,524 8 Claims. (Cl. 51-40) This invention relates to automatic cutlery sharpening devices, and more particularly to a new and novel design for an automatically operated knife-blade sharpening device.

This invention is especially intended for use as a coin operated, self-service device and may also be used in commercial installations such as butcher shops, restaurants, meat cutting houses, etc., where carving knives and such are frequently used and require frequent sharpening for effective cutting.

A man who is a skilled knife sharpener can, by honing and stropping, obtain a cutting edge on a knife that is far sharper than can be obtained on a mechanical grinding or honing machine; however, this edge is also far sharper than is necessary and due to the extremely narrow chisel point attained the knife is not able to hold its edge for long. Hand sharpening of knives, especially large, heavy bladed knives such as those used in the above mentioned shops, is a time consuming job that is costly in terms of labor expenses. I

This invention contemplates a device which will hone a blade to a reasonably sharp edge and yet does not require any particular skill to operate.

It is a primary object of this invention to provide a knife sharpening device that is adapted to rapidly and automatically sharpen a large variety of different types and sizes .of knives and knife-like objects to a keen edge.

It is a further object of this invention to provide a device for automatically and mechanically honing a knife blade by alternately honing one side and then the other of the blade in successive repeated steps.

Another object of this invention is to provide .a knife sharpening device wherein the knife blade is held fixed and a pair of rotating sharpening stones are adapted to be automatically positioned relative to the knife blade so as to alternately sharpen one side of the blade and then the other successively, in such a manner that the entire blade of the knife from the hilt to the point is sharpened equally regardless of configuration.

A further object of this invention is the provision of a knife sharpening device that guarantees uniform results is rugged in design, foolproof in operation, and relatively inexpensive to manufacture. I e

Other objectss and advantages will be apparent from the following detailed description and the accompanying drawings wherein: I 2

FIG. 1 is a partly sectionaLpartly side elevational view of the present invention;

FIG. 2 is a transverse sectional view taken along line 2-2 of FIG. 1;

FIG. 3 is an enlarged front end view of the knife holding mechanism of the invention;

FIG. 4 is a view similar to FIG. 3 but showing the knife holding mechanism in clamping relation to a blade;

FIG. 5 is a fragmentary bottom plan view of the knife clamp support bar, taken along lines 5-5 of FIG. 1, showing the means for automatically switching the position thereof;

FIGS. 6, 7 and 8 are semi-schematic fragmentary views of the sequence of steps which automatically change the position of the support bar;

port bar;

Patented June 6, 1961 FIG. 13 is a sectional view as seen from line 13-13 of FIG. 2; and,

FIG. 14 is a partial front elevational view as seen from line 14 14 of FIG. 1.

In detail, as best seen in FIGS. 1 and 2 the mechanism of the present invention is enclosed within a housing generally designated 1 Housing 1 comprises a relatively heavy base plate member 2 which may be fitted with rubber pad legs 3 if desired.

As used herein the words front, forward, forwardly, etc. will refer to the right-hand side of the device as seen in FIG. 1, the terms rear, rearwardly, etc. will refer to the other end of the device.

A pair of end members 4, 5 are mounted on the rear and front ends respectively of base plate 2 in vertical parallel opposed relationship and are interconnected along their Outer edges by means of a pair of relatively thin sheet-metal shell halves 6 and 7 (FIG. 2) that form the hood portion of housing 1 In order to gain access to the mechanism contained within housing 1 a removable cover 8 may be provided along the upper portions of shell halves 6 and 7.

Mounted on, and connected between end members (4, 5 are a pair of horizontal, parallel, longitudinally extending carrier rods 9, 10 which provide slidable support for a reciprocable grinding carriage, generally designated 12.

As best seen in FIG. 2 the grinding carriage 12 comprises a fiat transverse plate member 13 slidably mounted on carrier rods 9, 10 by means of a pair of sleeve bearing

blocks

14, 15. Plate 13 extends transversely across rods 9, 10. The outwardly extending ends of plate 13 are adapted to support the lower ends of a pair of generally C-shape'd

members

16, 17.

Members

16, 17 may be corinected to plate 13 by

bolts

18, 19 respectively.

The O-

shaped members

16, 17 are of substantially the same width as plate 13 and include a generally vertical section 21 which terminates at its upper end in a flat, inwardly declining platform surface 22 of the same width as section 21. For rigidity a web 23 may extend from the lower surface of platform 22 to the inner surface of portion 21. The two platforms are the same.

A boss 24, offset centrally from platform 22 along the lowermost edge thereof is adapted to rotatably receive a rod 25 therethrough. A collar 26 fitted to the lower exposed end of rod 25 serves as a keeper for a helical tor,- sion spring 27 that is placed around rod 25 between collar 26 and the lower end of boss 24. By positioning one leg of spring 27 against web 23, and allowing the other leg of the spring toreact against collar 26, limited rotational movement can be imparted to rod 25. I

The upper end of rod 25 projects above the upper surface of the inclined platform 22 and is secured to a generally rectangular base member 28 that is adapted to rotate with rod 25. As seen in FIG. 2 the base member28 is secured to rod 25 at a point off center by about the same degree of eccentricity as rod 25 is from platform 22. Thus in its non-rotated position the base member 28 is generally coterrninous with the outer edges of platform 22. Essentially platform 22 and base member 28 are two bearing plates adapted for relative rotational movement.

Atop each base member 28 is an electric motor 29 which is coupled to a speed reducer 30. The output shaft 31 of the speed reducer 30 extends inwardly toward the center of'the'machine and is parallel to the inclined plat- 'form 22. When member 28, and thus motor 29, are in a non-rotated position about the axis of rod 25, the output shaft 31 projects transversly of the longitudinal axis of the device of this invention. In FIGS. 1 and 2 the honing wheels 32 which will subsequently be more com pletely described.

FIG. 13 shows how the rotation of the motors 29 about the axis of shaft 25 may be limited; An arcuate slot 33 is formed in the platform 22 and said slot is adapted to slidably receive therein a portion of a downwardly projecting lug 42 that may be formed from the material of base member 28. Lug 42 prevents overrotation of motor 29 thus preventing the engagement of one grinding wheel with the other. An adjustment screw 44, extending into .the end of slot 33, may be set to limit the rotation of motor 29 as desired.

The grinding carriage 12 which has just been described assaaso is adapted to slide along carrier rods 9, 10 and yet mainconnecting roller chain 41 (FIG. 2).

Lead screw 34 is received in a thread selector type nut 43 (FIG. 1) which is securely attached to the under surface of plate 13 in such a manner that when lead screw '34 turns, a thread engaging panel within nut 43 engages either the left or right hand thread of the lead screw 34, thus causing the movement of grinding carriage 12. The panel arrangement within nut 43 is of standard design. Thus when the nut 43 has traveled to one end of the threaded portion of lead screw 34 the panel (not shown) 37 and a pair of chain sprockets 39, 40 with an inter- I is cammed to the thread of the other hand thus causing I 4 carriage 12 to travel in a reciprocatory path of equal length strokes governed by the length of the threaded portion of the lead screw 34.

One of the important features of this invention is that the knife blade (FIG. 1) is held in a clamping device, generally designated 46, and the grinding wheels 32 are adapted to move longitudinally along the knife blade 45 while performing the grinding operation. Because the grinding wheels 32 are spaced apart it is necessary that the clamping device 46 and hence knife blade 45 be moved transversely, so as to be brought first into grinding engagement with one grinding wheel 32 for one stroke of the operation, and then be moved transversely to the other grinding wheel to complete the cycle. This is accomplished by means of a horizontal, elongated, generally centrally located traversing bar 47.

The clamping device 46 is mounted on the forward portion of the traversing bar or carrier 47 (FIG. 1) and, as best seen in FIGS. 1, 3 and 4, comprises two opposed sets of vertically elongated, upwardly opening

clamping fingers

48, 49. Fingers 48 are stationary and are rigidly connected, along their lower portion, to the vertical inner face of a curb-like block 50 by means of bolts 54. Block 50 is rigid with the traversing bar 47 and is also provided with a plurality of transverse, inwardly opening, counterbored recesses 52 (FIG. 3). Recesses 52 are provided for the purpose of receiving therein the fixed ends of a plurality of helical compression springs 51 which are adapted to provide the clamping force for the

fingers

48, 49.

As seen in FIGS. 3, 4 the movable fingers 49 are pivotally mounted to a relatively short horizontal shaft 53. The lower portions 55 of fingers 49 are engaged by the free end of springs 51 which extend through apertures 56 in the lower portion of fingers 48. Springs 51 thus tend to yieldably urge the lower portions of

fingers

48, 49 apart, causing fingers 49 to pivot about shaft 53 thereby bringing the upper ends of said fingers into clamping engagement with the knife 45.

The finger arrangement for clamping device 46 consists of two fixed fingers 48, a broad front finger, and a narrower rearfinger spaced from the front finger by a gap 57. As seen by the dotted lines in FIG. 1, fingers 49 are four in number. Opposed to the front broad finger 48 are three narrow, independently pivoted

narrow fingers

49a, 49b, and 490. These are spaced from the rear pivoted finger 490! which engages the rear finger 48. This structure requires a separate spring 51 for each pivotal finger 49, hence in this present embodiment of the invention four springs 51 are required.

Thereason for having fingers 49 divided into narrow units is to facilitate the clamping of knife blades of non uniform cross-sectional thickness or those that maybe warped or bent.

Since the springs 51 are always tending to close

finger

48, 49 they must be forcibly opened when it is desired to unclamp them, as shown in FIG. 3. This is accomplished by means of aplurality of radial cams 58, one for each finger 49, connected to an axially spaced along a hand operated cam shaft 59. Cam shaft 59 is adapted to extend outwardly through the front end wall 5 and to be fitted with a handle 60 (FIG. 1) so the clamping device 46 may be manually controlled.

It will also be noted that the upper rear corners of both jaws 48 and jaws 49c and 49d are curved or rounded off, as at 74. This increases the range of sizes of knives that can be sharpened by the machine as it permits the grinding wheels 32 to follow down the curve at the end of a blade which is closely adjacent the rear end of the rear jaw 48 and jaw 49d. Likewise, with a blade that is so short as to just extend into the space 57 (FIG. 1), the wheels 32 can follow and sharpen the curved end of the blade in said space.

In order to properly position the knife blade 45, as shown in FIGS. 1 and 4, a guide device, generally designated 62, is provided. Guide device 62 comprises a flat, horizontal, longitudinally extending bar 63 (FIG. 3) which is held over the jaw opening of clamping device 46 and extends for substantially the entire length of

jaws

48, 49. Bar 63 is supported above

jaws

48, 49 at an adjustable height by means of a pair of support screws 64, 65 (FIGS. 1, 3). Screws 64, 65 are threadedly received by a pair of

rotatable arms

66, 67 respectively, that in turn are connected, coaxially, to a shaft 68 and are adapted to rotate therewith. Shaft 68 is rotatably journalled in a pair of brackets 69, 70 that are part of the structure of clamping device 46, as seen in FIG. 1. Rotation of shaft 68 is efiected by a crank 71 (FIGS. 3, 4) connected to the forward end thereof, a link 72, and another crank 73 connected to cam shaft 59.

When the

jaws

48, 49 are open as shown in FIG. 3 the guide device 62 is adapted to be positioned over the jaw opening. Thus, when a knife blade 45 is inserted into the jaws the cutting edge 75 is placed against the lower surface of bar 63. This correctly positions the knife blade 45 with respect to the grinding wheels 32. The guide 62 would interfere with the grinding procedure so it must be removed before the knife can be sharpened. This is very simply accomplished by linking the guide to the cam shaft 59. After the blade 45 is in position the handle 60 on the end of cam shaft 59 is turned clockwise as seen in FIGS. 3, 4 thereby releasing the lift on cam 58 from engagement with the lower portion of fingers 49. The fingers are thus spring urged into clamping engagement with the knife blade 45. At the same time the cams 58 are being released from engagement with fingers 49, the linkage from cam shaft 59 to shaft 68 causes shaft 68 to rotate about degrees counter-clockwise as indicated by arrow 76, FIG. 4.

It is desirable that there be a slight delay between the time that cam shaft 59 is first rotated and the time shaft 68 starts to rotate. This is so that the guide bar 63 will not be removed before the clamping

fingers

48, 49 have a chance to securely clamp the knife blade 45. Otherwise it would be possible for the knife blade 45 to become displaced from its correct position. This delay in action is accomplished by means of an elongated slot 77 in link 72 at the place where crank 73 is pivotally connected to 'said link. This allows cams 58 to be released from the fingers before the guide bar 63 is removed from the knife blade 45.

A torsion spring 78 (FIG. 1) on the rear end of shaft 68 may be utilized to yieldably urge shaft 68 in a clockwise direction thereby assuring the positioning of guide device 62 above the

jaws

48, 49. A shoulder 79 may be provided on each

arm

66, 67, adjacent the pivot point, that is adapted to abut the outer surface of fingers 48 (FIG. 3). This further facilitates the correct placement of guide 62 with respect to the knife 45 and also prevents overrotation of

arms

66, 67 that would result should looseness develop in the various linkages associated therewith.

Traversing bar 47, is adapted for limited transverse movement across the central axis of the machine. The rear, lower surface of bar 47 is fitted centrally, with a triangular shaped wedge element 81 (FIGS. 1, 5 and 9) with its apex placed exactly on the center of bar 47 and directed toward the front of the machine (FIG. 5).

Bar 47 is slidably received in a transverse, channel shaped recess comprising an upper '82 and lower 83 surface adapted to bear against the upper surface of bar 47 and the lower surface of the rear end of Wedge 81 respectively (FIG. 1).

The front end of bar 47 is supported for transverse movement by means of a transverse rod 84 (FIGS. 3, 4, 5, 10) which is connected, intermediate its ends, to bar 47 as by bracket 85. With reference to FIG. 10 rod 84 is slidably supported in a pair of bearing blocks 86 '(onlyone shown) equally spaced on either side of bar 47.

Rod 84 is bored from both its ends for approximately one third its length. A pair of helical compression springs 87, 88 are positioned within the bores, one in eachend of rod 84. Theends of

springs

87, 88 that are against the blind ends of the bores are adapted to push thereagainst by means of a pair (only one shown) of adjustable stud "elements 89. Each stud 89 is a partially threaded rod that is of suitable diameter to be slidably received within a bore in rod 84. The end of the stud that is within the bore is adapted to engage the outer or free end of one of the springs 87, 8-8. The end of stud 89 that is outside the bore of rod 84 is threadedly received by a flange 90 that may be integral with and at a fixed distance from bearing blocks 86.

It is to be understood that the adjustable stud and .s'pring arrangement shown in FIG. 10 exists on both sides of traversing bar 47 and both such arrangements are ;'spaced equidistant from the center line of said bar 47 \vhen the same is in a neutral position.

By making the correct adjustment on studs 89 the bar '47 may be yieldably urged to a neutral position mid-way between said studs. When the traversing bar 47 is 'forcibly moved to a position other than its neutral position, springs 87, 88 tendto yieldably'urge saidbar back to said neutral position.

The aforementioned transverse movement of traversing bar 47, and therefore knife holder 46, is obtained by means of a pair'of wedge elements 93, 95 (FIG. 5). As seen in FIGS, 1, 2 the rtaveling nut 43 that is adapted to impart reciprocable motion to carriage 12 is part of a ho'using 91 which is provided with an upwardly extendin'g flange 9 2 terminating in a centrally placed, horizontal wedge-shaped camelement 93. Cam 93 is integral with housing 92 and therefore is subject only to longitudinal reciprocation along with the grinding carriage 12.

FIGS. 5, and 9 through 12 are all bottom views of the t'r'a've'rsingbar 47 and illustrate the sequence of the cycle of operations. As'seen in FIGS. 5, 9, and 10, on the forward end of bar 47, beneath knife holder 46, and just rearwardly of bracket '85, there is a generally triangular, centrally located, pivotal wedge element 95. The wedge element 95 is adapted for'lirnited rotational movement abouta pivot 96. "The 'o'uter 'ends oftliebase bfelement 6 are cut at a bias to enable said base to be met squarely by an abutment 97 which limits the rotational movement of element 95. Wedge element 95 is always in a rotated position either as shown in FIG. 5 or 10.

FIG. 5 shows the traversing bar 47 in a central or neutral position. As will be subsequentlydescribed, the carriage 12 is adapted to always come to rest at its rear position, however, for sake of description it is assumed that FIG. 5 shows the beginning of a knife sharpening cycle.

With the traversing bar 47 in a neutral position as shown in FIG. 5, the grinding carriage 12 starts to move forwardly as indicated by arrow 99. Because cam 93 is integral with carriage 12 it also moves. Upon reaching the triangular wedge 95 (FIG. 9) cam 93 forcibly cams bar 47 laterally or transversely to one side in the direction of arrow 98. Upon continued forward movement of cam 93, the face thereof that engages one of a pair of opposed shoulders 120 on wedge 95 opposite the point causes the latter to rotate about pivot 96 (FIG. 10) to the opposite rotated position. At this point the traversing bar 47 is fully displaced transversely and the grinding carriage 12 is adapted to commence its rearward stroke. A spring loaded, ball and socket detent 100 in wedge 95 is adapted to register with complementary recess 101 in bar 47 to prevent unintentional rotation of wedge 95.

When cam 93 is withdrawn from the triangular wedge 95, a centrally placed, spring loaded latch plunger 103 (FIGS. 1, 5, 9) that is now exposed from behind the base of the fixed wedge 81 snaps outwardly to engage a fiat portion of said wedge 81 adjacent the base thereof and thus hold bar 47 in its off-center, operative position.

The grinding wheel 32 that is now brought into contact with the knife blade 45 sharpens one side of the blade during the rearward travel of carriage .12 (FIG. 6).. Even though the knife blade 45 may be shorter than the length of the machine, the carriage 12 returns completely to its rearmost position where a rearwardly extending projection 104 (FIGS. 1, 11) on the rear end of cam element 93 is adapted to register with and depress latch plunger 103. With the plunger 103 withdrawn from engagement with wedge 81 the springs '87, 88 will move traversing bar 47 until the wedge '81 engages traversing cam 93 thus allowing a portion of the base of the triangular wedge 81 to extend in front of plunger 103. The carriage '12 now moves forwardly again (FIG. 12) thus allowing wedge 81 and the traversing bar 47 to progressively return to a neutral position as indicated by arrow 105.

The ensuing cycle is the same as the previous except that now the forward pivoted wedge element 95 is in the position shown in FIG. 10 thus causing the traversing bar 47 to be moved the opposite way and enabling the other side of the knife blade 45 to be sharpened.

Hence, the grinding wheels travel in alternate directions longitudinally of the machine while the knife, held in clamping device 46, is shifted to one side and then the other to be alternately honed on each side. It will be noted that torsion springs 27 (FIG. 2) yieldably urge wheels 32 to a tilted position to be engaged by the knife blade as the clamping device 46 is shifted. The inward limit of tilt of wheels 32 is such that they are never permitted to meet but are always yieldably engaging the wardly so that it will follow and sharpen the curved portion of the blade.

The yieldably urged wheels 32 will also'sharpen any other portion of the blade .thatmay be curved or bent from a straight line.

complished with the use of a lubricant.

As previously mentioned, the grinding wheels make their return, forward stroke with the knife clamping device in the'neutral or central position between the wheels (FIG. 7). Thereafter the next consecutive rearward sharpening stroke is accomplished on the opposite side of the blade (FIG. 8).

As an added precaution to insure that the traversing bar 47 is always returned to its neutral, centerline position on the return stroke of carriage 12, a pair of opposed, divergently opening, longitudinal guide members 106, 107 are mounted on the underside of bar 47 so that they may cooperatively engage and guide a lug-like projection 108 that is atop the forward end of cam 93 (FIG. The guide members 106, 107 are sufficiently narrow in width so that they will not interfere with the cam 93 on the rearward travel of the carriage 12.

The honing and sharpening of knives is normally ac- In order to deliver lubrication to the grinding wheels 32 the exposed end of a wick 110 is provided (FIG. 1). The lower end of the wick 110 is held within a lubricant reservoir 111 that is mounted on the upper rear portion of traversing bar 47.

As the grinding carriage 12 nears the end of its return or grinding stroke the wheel 32 that has just finished grinding is adapted to wipe against the wick 110 thus picking up some lubricant therefrom. This action will also tend to remove any loose particles of grit or metal from the face of the wheel 32.

Each grinding wheel 32 is adapted to alternately wipe against the wick 110 at the completion of its grinding stroke. In order to refill the reservoir 111 a filling plug 112 may be provided as shown.

To prevent grit from grinding wheels 32 and grinding lubricant from interfering with the function of moving parts such as lead screw 34 and nut 43, rods 9 and 10 and

bearings

14 and 15, motor 37, clamping device 46, and the like, the same are shielded from the grinding wheels by a pair of pan guards 113. Guards 113 may be secured to wings 114 (FIG. 2) on clamping device 46 by rivets 115 and extend throughout the length of the apparatus. It is noted that said guards are broken away in FIG. 1 to reveal details shielded thereby.

Since the knife clamping device 46 shifts back and forth between grinding cycles, an opening 117 (FIGS. 1, 14) must be provided in the front of the machine through which the shaft 59 projects. Said opening is covered by a panel 118 which is secured to clamping device 46 and bracket 70 and moves therewith. The width of panel 118 is such that it overlaps opening 117 sufiiciently to cover it in all positions of device 46. Panel 118 is further provided with a plastic lined opening 116, aligned with

jaws

48, 49, for insertion of the blade 45 of the knife.

It has been determined from actual use of this invention that six to eight complete cycles are suflicient to sharpen the dullest of knives. Any further grinding would only needlessly grind away the knife and needlessly wear out the grinding wheels. The number of cycles can be automatically controlled by such means as an electrical or mechanical accumulator that will turn oil the machine after the desired number of cycles.

As previously explained the machine of this invention may be designed for coin operation and provided with suitable automatic controls, including the above mentioned accumulator. In such case, the individual operator inserts the knife through an opening 116 and clamps the jaws as described. Insertion of a coin in the conventional slot then initiates the cycling of the machine which continues until an even number of passes have been made by the grinding wheels. It is important to note that the accumulator should be set for an even number of forward and return strokes of the grinding wheel carriage so that opposite sides of the blade will be alternately honed the same number of times.

It is, of 'course,'evident that many minor modifications and changes can be resorted to in the manufacture of this invention. Such changes however would not depart from the spirit of this invention or the scope of the following claims.

I claim:

1. Knife sharpening apparatus comprising: clamping means adapted to hold a knife in a central plane with its cutting edge exposed and extending along a predetermined line in said plane, a pair of motor driven, rotatable abrasive wheels, a carriage mounted for reciprocating movement in a path parallel to said line and carrying said abrasive wheels on opposite sides of and inclined relative to said plane, drive means connected to said carriage for reciprocating the same in said path back and forth past said clamping means, and means for shifting said clamping means transversely of said plane for moving said knife into positions to be engaged by each of said wheels in turn, said last mentioned means including a switching wedge mounted on said clamping means and an element on said carriage engageable with alternate sides of said wedge during alternate reciprocations of said carriage for urging said clamping means away from the side of said wedge which is engaged and to a position whereby said knife will be engaged by one of said abrasive wheels, and latch means for holding said clamping means in said position during movement of said abrasive wheel along said cutting edge.

2. An automatic blade sharpening device comprising: a housing, an elongated blade carrier mounted in said housing for transverse movement from a central, neutral position to first and second operative positions spaced on opposite sides of said neutral position, opposed spring means acting between said housing and said carrier for yieldably maintaining said carrier in said neutral position, blade gripping means mounted on one end of said carrier for movement therewith and adapted to hold a blade with its cutting edge exposed in a generally vertical plane parallel with said carrier, elongated support members mounted in said housing and extending parallel to said carrier, a carriage slidably mounted on said support members for reciprocation during a sharpening stroke from said other end to said one end, motor means for so reciprocating said carriage, a pair of grinding means mounted on said carriage on opposite sides of said carrier and positioned to intersect the cutting edge of a blade held in said jaws with said carrier in said operative positions, switch means secured to said carrier adjacent to said one end and presenting surfaces oppositely inclined relative to said plane, a cam element carried by said carriage and alternately engageable with said surfaces for alternately shifting said carrier to said operative positions at the end of said return stroke, latch means at said other end of said carrier for holding said carrier in said operative positions, and a projection on said carriage engageable with said latch means for releasing the same at the end of said sharpening stroke.

3. An automatic blade sharpening device comprising: a housing, an elongated blade carrier mounted in said housing for transverse movement from a central, neutral position to first and second operative positions spaced on opposite sides of said neutral position, opposed spring means acting between said housing and said carrier for yieldably maintaining said carrier in said neutral position, blade gripping means mounted on one end of said carrier for movement therewith and adapted to hold a blade with its cutting edge exposed in a generally vertical plane parallel with said carrier, elongated support members mounted in said housing and extending parallel to said carrier, a carriage slidably mounted on said support members for reciprocation during a sharpening stroke from said one end of said carrier to the other end and a return stroke from said other end to said one end, motor means for so reciprocating said carriage, a pair of grinding means mounted on said carriage on opposite sides (if said carrier and positioned tdintetsect, the cutting edge of;

a bladeheld in said jaws with said carrier in said operative positions, switch means secured; to said carrier adjacent said one end and presenting surfaces, oppositely inclined relative to said plane, a cam element carried by said carriage and alternately engageable with said surfaces for alternately shifting said carrier to said operative positions at the end of said return stroke, latch means at said other end of; said carrier forholding said carrier in said operative portions, and a projection on said'carriage engageable with said latch means for releasing the same at the d, o said. harpenins tr ke d sw t h means including a wedge element provided with a pair of sides converging to a point directed toward said" other end, a n r Pi ot onnecting. aid. e geel t o said r i fo s n in betwee pqs t onsw h s p int n ppo te ides- Qf. sa dplane, and apairo s ou ers on said wedge on opposite sides. of said pivot and remote from said point and engageable by said cam element for sorswinging said wedge element:

4. An automatic blade sharpening: device comprising: a housing, an elongated blade carrier mounted in said housing for transverse movement from a central, neutral position to first and second operative positions spaced on opposite sides of said neutral position, opposed spring means acting between said housing and said carrier for yieldably maintaining said carrier in said neutral position, blade gripping means mounted on one end of said carrier for movement therewith and adapted to hold a blade with its cutting edge exposed in a generally vertical plane parallel with said carrier, elongated support members mounted in said housing and extending parallel to said carrier, a carriage slidably mounted on said support members for reciprocation during a sharpening stroke from said one end of said carrier to the other end and a return stroke from said other end to said one end, motor means for so reciprocating said carriage, a pair of grinding means mounted on said carriage on opposite sides of said carrier and positioned to intersect the cutting edge of a blade held in said jaws with said carrier in said operative positions, switch means secured to said carrier adjacent said one end and presenting surfaces oppositely inclined relative to said plane, a cam element carried by said carriage alternately engageable with said surfaces for alternately shifting said carrier to said operative positions at the end of said return stroke, latch means at said other end of said carrier for holding said carrier in said operative positions, and a projection on said carriage engageable with said latch means for releasing the same at the end of said sharpening stroke, said blade gripping means including a pair of opposed jaws movable toward each other for gripping said blade therebetween, and one of said jaws being formed in independently movable sections, yieldably urged toward the other of said jaws for accommodating a non parallel sided blade.

5. An automatic blade sharpening device comprising: a housing, an elongated blade carrier mounted in said housing for transverse movement from a central, neutral position to first and second operative positions spaced on opposite sides of said neutral position, opposed spring means acting between said housing and said carrier for yieldably maintaining said carrier in said neutral position, blade gripping means mounted on one end of said carrier for movement therewith and adapted to hold a blade with its cutting edge exposed in a generally vertical plane parallel with said carrier, elongated support members mounted in said housing and extending parallel to said carrier, a carriage slidably mounted on said support members for reciprocation during a sharpening stroke from said one end of said carrier to the other end and a return stroke from said other end to said one end, motor means for so reciprocating said carriage, a pair of grinding means mounted on said carriage on opposite sides of said carrier and positioned to intersect the cutting edge of a blade held in said jaws with said carrier in said operative positions, switch means secured to said carrier adjaassessed cent said one end and presenting surfaces oppositely in clined relative to said plane, a cam element carried by said carriage and alternately engageable with said sur-: faces for alternately shifting said carrier to said operative positions at the end of said return stroke, latch means at said other end of said carrier for holding said carrier in said operative positions, and a projection on said carriage engageable with said latch means for releasing the same at the end of said sharpening stroke, said blade gripping means including a pair of opposed jaws movable toward each other for gripping said blade therebetween, and one of said jaws being formed in independently movable sections, yieldably urged toward the other of said jaws for accommodating a non parallel sided blade, and positioning means, movable with said jaws, for positioning the cutting edge of a blade to be gripped by said aws.

6. An automatic blade sharpening device comprising:

a housing, an elongated blade carrier mounted in said opposite sides of said neutral position, opposed spring means acting between said housing and said carrier for yieldably maintaining said carrier in said neutral position, blade gripping means mounted on one end of said carrier for movement therewith and adapted to hold a blade with its cutting edge exposed in a generally vertical plane parallel with said carrier, elongated support members mounted in said housing and extending parallel to said carrier, a carriage slidably mounted on said support members for reciprocation during a sharpening stroke from said one end of said carrier to the other end and a return stroke from said other end to said one end, motor means for so reciprocating said carriage, a pair of grinding means mounted on said carriage on opposite sides of said carrier and positioned to intersect the cutting edge of a blade held in said jaws with said carrier in said operative positions, switch means secured to said carrier adjacent said one end and presenting surfaces oppositely inclined relative to said plane, a cam element carried by said carriage and alternately engageable with said surfaces for alternately shifting said carrier to said operative positions at the end of said return stroke, latch means at said other end of said carrier for holding said carrier in said operative positions, and a projection on said carriage engageable with said latch means for releasing the same at the end of said sharpening, a lubricant applying wick mounted on said carrier for movement therewith and positioned to be engaged alternately by said grinding means on said sharpening stroke.

7. An automatic blade sharpening device comprising: a housing, an elongated blade carrier mounted in said housing for transverse movement from a central, neutral position to first and second operative positions, opposed spring means acting between said housing and said carrier for yieldably maintaining said carrier in said neutral position, blade gripping means mounted on one end of said carrier for movement therewith and adapted to hold a blade with its cutting edge exposed in a generally vertical plane parallel with said carrier, elongated support members mounted in said housing and extending parallel to said carrier, a carriage slidably mounted on said support members for reciprocation during a sharpening stroke from said one end of said carrier to the other end and a return stroke from said other end to said one end, motor means for so reciprocating said carriage, a pair of grinding means mounted on said carriage on opposite sides of said carrier and positioned to intersect the cutting edge of a blade held in said jaws with said carrier in said operative positions, switch means secured to said carrier adjacent said one end and presenting surfaces oppositely inclined relative to said plane, a cam element carried by said carriage and alternately engageable with said sur faces for alternately shifting said carrier to said operative positions at the end of said return stroke, latch means at said other end of said carrier for holding said carrier in.

said operative positions, and a projection on said carriage engageable with said latch means for releasing the same at the end of said sharpening stroke, said grinding means including motor-driven abrasive wheels, pivot means connecting said wheels to said carriage for swinging a portion of the peripheries of said wheels toward and away from said plane, spring means yieldably urging said por tions oppositely inwardly toward said plane for yieldably engaging the cutting edge of a blade held in said clamping means during said sharpening stroke, and adjustable stop means limiting inward movement of said portion for preventing interference between said wheels.

- 8. A blade sharpening device for a blade having an elongated cutting edge along a marginal portion thereof, comprising: blade gripping means for holding such 'blade with said marginal portion and edge exposed, a pair of spaced abrasive means, means mounting said pair of spaced abrasive means at opposite sides of said marginal portion of such blade when the latter is held by said blade gripping means for repeated reciprocable movement of said abrasive means longitudinally of such marginal portion in a direction from one end of the latter to and past the other-end and back again, and means for alternately moving-said abrasive means into engagement with one side of said marginal portion at said edge and at said one end of said movement and yieldable means for yieldably holding each of said abrasive means in said engagement during said movement thereof from said one end to said other end, and means for holding said. pair of abrasive means out of engagement with said marginal portion during said movement of said pair of abrasive means from past said other end of said portion back to said one end.

References Cited in the-file of this patent UNITED STATES PATENTS 981,511 Winn t. Jan. 10, 1911 1,480,791 Stein et al. Jan. 15, 1924 1,744,752 Crespo Jan. 28, 1930 FOREIGN PATENTS 111,575 Great Britain Dec. 6, 1917 227,902 Great Britain Jan. 20, 1925