US2728170A - Sickle bar grinding machine - Google Patents

Description

Dec. 27, 1955 KQRBER 2,728,170

SICKLE BAR GRINDING MACHINE Filed Feb. 19, 1952 3 SheetsSheet l 26 7' 25 so. r'

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Jesse lfor'ber Dec. 27, 1955 J. H. KORBER 2,728,170

SICKLE BAR GRINDING MACHINE Filed Feb. 19, 1952 3 Sheets-Sheet 2 IN VEN TOR.

Jesse Korber United States Patent SICKLE BAR GRINDING MACHINE Jesse H. Korber, Pawnee City, Nebr. Application February 19, 1952, Serial No. 272,418

1 Claim. (Cl. 51-33) This invention relates to grinding apparatus, and particularly to grinding apparatus adapted for the sharpening of the pointed or triangular-shaped teeth of sickles such as those used in mowers.

In mowers used for mowing hay and like crops, the cutting action is in most instances obtained by a reciprocating sickle having a series of triangularly shaped or pointed teeth extended forwardly from the forward side of the sickle bar, and these triangular teeth are sharpened along one edge thereof so that there is a sharp edge along each side of each tooth and in a common plane so that these teeth may cooperate with the stationary elements that are afforded on the stationary elements that are afforded on the stationary cutter bar of the mower. The normal grinding or sharpening operation on sickle bars of the aforesaid character is performed by holding the adjacent edges of two adjacent teeth in contact with a rotating grinding wheel that has angular surfaces that conform with the desired shapeof the teeth and the edge that is to be ground thereon, and it is well known that the desired grinding operation is quite difficult to perform in the field, or in the ordinary farm workshop because of the weight of the sickle bar and because of the tendency of the metal to excessively heat when the grinding operation is performed, thus producing what are known as burns on the edges that are being ground.

In view of the foregoing it is the primary object of the present invention to afford a grinding apparatus for sickles of the aforesaid character whereby an ordinary unskilled worker may readily and easily grind a good cutting edge on the teeth of such a sickle without danger of burning or otherwise damaging the metal of the sickle.-

Other and more specific objects of the present invention are to afford such a grinder for sickles of mowers that is of such a character that the location of the work with relation to the grinding wheel may be readily and easily accomplished, and in which the progress of the Work may be readily checked by visual inspection that may be performed in a convenient and easy manner.

Other and more specific objects of the present invention are to afford a sickle grinder of the aforesaid character wherein the mechanism is adapted for ready and easy adjustment so that a proper and satisfactory grinding operation may be attained despite progressive wear of the grinding wheel, and to afford such a grinder wherein the relative movements that are desired between the teeth of the sickle and the grinding wheel are automatically attained, and in which such movements are attained in such a way that the pressure between the work and the grinding wheel is maintained at all times at a value which will insure that a satisfactory grinding operation will be attained and damage to the sickle bar will be avoided.

Another object of the present invention is to afford a sickle grinder of the aforesaid character wherein the mounting of the work in the machine may be accomplished in a simple and expeditious manner, and it is also an object of this invention to aiford a sickle grinder which may, in a very simple manner, be converted into use in sharpening tools and knives and for other general grinding purposes that may be encountered in a farm workshop.

Other and further objects of the present invention will be apparent from the following description and claim and are illustrated in the accompanying drawings which, by way of illustration, show a preferred embodiment of the present invention and the principle thereof and what 1 now consider to be the best mode in which I have contemplated applying that principle. Other embodiments of the invention embodying the same or equivalent principle may be used and structural changes may be made as desired by those skilled in the art without departing from the present invention.

In the drawings:

Fig. 1 is a front perspective view of a sickle grinder embodying the features of the invention;

Fig. 2 is a plan view thereof;

Fig. 3 is a vertical sectional view taken along the line 33 of Fig. 2;

Fig. 4 is an enlarged fragmental portion of Fig. 2;

Fig. 5 is an enlarged sectional view taken along the line 55 of Fig. 3;

Figs. 6 and 7 are enlarged front elevational and top plan views respectively showing the relation of the sickle and the grinding wheel; and

Fig. 8 is an enlarged portion of Fig. 3 showing the sickle-grinding wheel relation.

For purposes of disclosure the invention is herein illus trated as embodied in a sickle grinder 20 that comprises a bed 21 having an elongated mounting bar 22 arranged along its forward edge; and on the mounting bed 21, a grinding wheel 25 is mounted for rotating movement about a horizontal axis that is parallel to the front mounting bar 22 and for movement in a generally up and down direction so that a grinding relationship of the wheel 25 to a sickle bar 26 may be varied, the sickle an ordinary grinder for brought into the desired grinding relationship with respect to the grinding wheel 25.

The mounting bed 21 in the present instance is afforded as a part of a table structure, having two front legs 29 and a single rear leg 30 extended downwardly therefrom so that the bed may be supported in the manner of a table for floor mounting. As will be evident in Figs. 6 and 7 of the drawings, the sickle 26 is made up in the conventional manner so as to afford pointed teeth 26T which are ground along each of their forward edges so as to define cutting edges 26C that are disposed in a common plane defined by the surfaces on one face of the teeth 26T. The edges 26C of the teeth 26T, of course, are ground to substantially a predetermined cutting angle, and this is accomplished through the use of a grinding wheel such as the grinding wheel 25 which has angularly related grinding surfaces 25R and 25L, as is customary in grinding wheels for this particular purpose. As will be hereinafter pointed out in detail, the sickle 26 is mounted on mounting means carried on the front mounting bar 22 so that the sickle may be shifted laterally and by a rocking movement into and out of a grinding relationship with respect to the grinding wheel 25, and also to enable the sickle bar to be shifted in an endwise direction to bring different ones of the V-shaped spaces between the teeth into alignment with the center of the grinding wheel 25.

As herein shown, the supporting bed 21 as well as the leg structures are formed from angle iron sections, and these sections are so arranged that they may be cut and punched to the proper form, and after being shipped to the user, may be readily assembled to afford the desired support structure for the present machine. Thus, the bed '21 is formed on three sides by a single angle iron piece that has a rear bar or section 21A, Fig. 2, and two side sections 21L and 21R, one flange of the angle iron being appropriately notched as at 21N at both ends of the rear member 21A and being bent so that the side members 21L and 21R diverge slightly in a forward direction. The forward ends of the side members 21L and 21R are disposed beneath the horizontal flange of the front mounting bar 22, which is, of course, formed from an angle iron which in the present instance is somewhat larger in cross-sectional size than the other angle iron members, and the forward ends of the members 21L and 21R are connected to the front mounting rail 22 by means of bolts 33. The upper ends of the front legs 29 have their forward flanges connected to the front mounting bar by means of bolts 34, while the upper end of the rear leg is connected to the rear member 21A by means of a bolt 35. The two front legs 29 have angle braces 36 extended therefrom upwardly and toward each other and connected to the vertical flange of the front bar 22, the connections at the opposite ends of the braces 36 being accomplished by bolts 37. Similarly, braces 38 are extended angularly between the front legs 29 and the adjacent side members 21L and 21R respectively, and the connection at opposite ends of these angle braces is afforded by means of bolts (not shown). The rear leg is held in its proper relationship by stretcher members 40 connected by bolts 41 to the rear leg 30 and connected by bolts 42 to the respective front legs 29. Thus, a relatively rigid table structure is afforded, the top of which constitutes the bed 21 upon which the mounting and operating elements of the present apparatus are disposed.

The mounting for the sickle bar 26 is afforded by means including three upstanding lugs 45 afforded on the upper or horizontal flange of the front mounting bar 22, and these lugs are equally spaced so that one such lug is located at each of the opposite ends of the bar 22, while the third lug 45 is located substantially centrally of the bar 22, and a mounting rod 46 is extended through the several lugs 45 in a stationary relationship to serve as a slidable and pivotal support for a pair of clamps 50. One of these clamps 50 is mounted on the rod 46 on each side of the central supporting lug 45, and these clamps may move with a sliding action longitudinally along the rod 46, and may rock to a limited extent about the axis of the rod 46. Each clamp 56 includes a pair of opposed jaws 58F and 59R that are spaced apart and are adapted to receive the back or bar portion of the sickle and to clamp the same by means of a clamping screw 50C that extend through the front jaw 50F and may be tightened to press and clamp the bar against the rear jaw 50R. Each of these clamp members 50 has a forwardly extending tail portion SQT at its front lower end, so that when the clamp '50 rocks in what may be termed a forward direction, the tail SOT will strike the corner of the angle bar 22 and act as a stop to limit the forward tilting movement of the clamp, and this relationship is utilized to limit the forward rocking movement of the sickle shown in dotted outline in Fig. 8 to a position wherein the cutting edges are spaced from the grinding wheel 25 and are located so that they may be readily inspected by the user.

The grinding wheel 25 is supported on the bed 21 by means including a relatively long and flat mounting plate 60 that extends between and rests upon the front bar 22 and the rear member 21A of the bed, and it will be observed that this mounting plate has a slot 685, Fig. 4, extending rearwardly from its front edge for purposes that will appear hereinafter. Also, it will be noted that on each side of the forward end of this slot 60S, smaller elongated bolt-receiving slots 61 are provided through which fastening bolts 62 may be extended downwardly through the horizontal flange of the front bar 22 for clamping the forward end of the mounting plates 60. in position with respect to the front bar 22. Similarly, at

the rear edge of the mounting plates 66, there is an elongated slot 63 extending in a front to rear direction and through which a clamping bolt 64 may extend into the horizontal flange of the rear member 21A, thus to fix the rear end of the mounting plate 60 in position on the bed 21.

In providing for the desired up and down movement of the grinding wheel 25, this grinding wheel is mounted by means of the usual wheel-mounting structure on one end of a rotatable shaft 65 that is carried in a bearing 66 that is afforded along the forward end of a relatively wide and fiat mounting or rocking arm 67, the rear end portion of the rocking arm 67 having an enlarged bearing structure 68 formed thereon through which a mounting shaft 69 extends. This mounting shaft 69 is supported statiouarily in a horizontal position and parallel to the forward rod 46 by means such as a pair of upstanding mounting lugs 73 that are formed integrally with the plate 60. The mounting lugs 79 are so located that the rocking arm 67 is disposed directly over the slot 608 that is formed in the mounting plate 60, and the rocking arm 67 has a slot 678 formed therein to facilitate the connection of an actuating means to the rocking arm 67. Thus, along the opposite sides of the slot 67S and on the lower surface of the rocking arm 67, a pair of downwardly extending lugs 67L are formed and the upper end of a link 72 is pivoted between these two lugs 67L by a pin 73. The lower end of the link 72 is mounted in surrounding relationship toan eccentric 7415 that is fixed to a relatively large gear 74 that is rotatively supported on a shaft 75 in a gear housing 76 that projects downwardly from the lower face of the mounting plate 60 just to the right of the slot 608 as viewed in Fig. 5 of the drawings. The gear housing 76 also serves as a housing for a relatively small pinion 77 that is meshed with the gear 74 the pinion 77 being fixed on a drive shaft 78 that extends through the gear housing 76. The drive shaft 78 has a relatively large V-belt pulley 79 fixed thereto, whereby the shaft 78 may rotate the gears 77 and 74, and the link 72, and the rocking arm 67 may be caused to move up and down through a limited stroke that is determined by the eccentricity of the eccentric 74E. The grinding wheel 25 as herein shown is mounted on the left hand end of the shaft 65, as viewed in Fig. 5 of the drawings, and for purposes that will appear hereinafter, a conventional grinding wheel 125 is mounted on the opposite end of the shaft 65. Preferably a guard 25G is mounted on the arm 67 so as to overhang a portion of the grinding wheel 25 as shown in Figs. 1, 3 and 4. Between the conventional grinding wheel 125 and the adjacent end of the bearing sleeve 66, a relatively small V-belt pulley 82 is fixed on the shaft 65, and the desired operating or rotating movements are imparted to the shafts 65 and 78 by means that are connected to the aforesaid V- belt pulleys 79 and 82.

In the present instance, the drive means is supported on the rear portion of the mounting plate 60, rearwardly of the lugs 70, and the driving means may take any conventional form in accordance with the power facilities at the particular farm where the sickle grinder is to be used. In the present instance an electric motor 85 is shown as bolted to the mounting plate 60, and a V-belt pulley 86 is provided on the extreme end of the motor shaft and is connected by means of a V-belt 87 to the large belt pulley 79 so as to drive the eccentric 74E. Another V- belt pulley 88 is also fixed onthe motor shaft, and this is connected by means of a V-belt 89 to the V-belt pulley 82 that is fixed on the shaft 65. It will be observed that the axes of the motor shaft and the rocking plate 67 are so related to the path of movement of the shaft 65 that the belt 89 maintains a proper tension throughout the entire reciprocating or up and down stroke of the grinding wheel.

With the structure that has thus far been described, the grinding wheel 25 will be constantly rotated, and

B! u the grinding wheel will also move up and down at a relatively slow rate between the full line position and the dotted line position shown for the grinding wheel in Fig. 8 of the drawings. It is important to note the relationship between the grinding wheel 25 and its reciprocating stroke and the work holders or clamps 50 and the sickle teeth 26T. Thus it will be noted that the axis of the rod 46 upon which the workholding clamps 50 are adapted to rock is disposed a substantial distance forwardly or to the right in Fig. 8 with respect to the forward edge of the grinding wheel 25, and the form of the rear jaws 50R is such that when a sickle is clamped in position in the clamps 50, the sickle 26 and the clamps 50 must be rocked to what may be termed a forward over-center position such that the weight of the sickle is disposed rearwardly or to the left in Fig. 8 with respect to the axis of the mounting rod 46. The weight of the sickle 26 is thus eflective to tend to rock the clamps and the sickle in a counter-clockwise direction, Fig. 8, or in other words toward an engaging relationship with respect to the grinding wheel. This eccentricity of the center of gravity of the sickle and its mounting structure is so arranged, as shown in Fig. 8, that a sufficient force will be effective upon the sickle to hold the teeth thereof in engagement with the angular surfaces 25L and 25R of the grinding wheel, and yet this force is sufiiciently low to insure that the sickle will not be excessively heated and burned in the course of a normal grinding operation.

The relationship between the sickle and the grinding wheel 25 is such that when the grinding wheel is in its lower position, it will force the sickle through a rocking movement to the right or in a clockwise direction, Fig. 8, to the full line position shown in Fig. 8, and in this relationship, the grinding wheel is elfective to grind the lowermost portions of the edges 26C of the sickle teeth. Then, when the motion of the grinding wheel 25 reverses and the grinding wheel moves upwardly toward its dotted line position of Fig. 8, the sickle 26 will rock gradually to the left-hand dotted line position of Fig. 8, and this movement progresses as the wider or upper portions of the V-opening engage with the sickle, and when the grinding wheel 25 has reached its uppermost position, the wheel will be grinding the portions of the edges 26C that are adjacent to the points of the teeth 26T.

In the use of the present apparatus, it is found that the location of the work or the sickle 26 in a longitudinal sense with respect to the grinding wheel 25 need not be accurately established by the operator, it only being necessary for the operator to move the sickle endwise into the approximate position required, after which the operator may again rock the sickle toward the grinding wheel so as to allow the same to bear against the grinding wheel due to the action of gravity as above described. Then, in the up and down reciprocating movements of the grinding wheel, the grinding wheel may initially be grinding against but one of the edges 26C of the particular V- shaped space that has been selected, but it is found in practice that in the first one or two reciprocations of the grinding wheel, the forces exerted on the sickle are suificient to cause the sickle and its mounting clamps 50 to move longitudinally along the mounting rod 46 until the teeth that are to be ground are centered upon and are both engaged with the grinding wheel in the proper relationship. The operator then allows the grinding operation to progress for a short time, after which the operator may rock the sickle to its retracted position illustrated by the right-hand dotted line relationship shown in Fig. 8 of the drawings, and when the sickle has been thus retracted, the operator may look downwardly onto the ground edges of the sickle to determine whether or not the grinding operation has progressed to a sufiicient extent. If the grinding has been completed as shown by such inspection, the operator may shift the sickle another tooth space in one direction or the other and establish the grinding relationship in respect to other teeth as hereinabove described.

It will be observed that the range of longitudinal movement of the clamps 50 is limited by the central lug and by the length of the rod 46 to substantially one-half the length of the normal sickle that has been illustrated particularly in Fig. 1 of the'drawings, and this condition is taken care of in practice by so mountingthe sickle in the clamps 50 that the teeth throughout about one-half of the sickle may be ground in the normal range of movement of the clamps along the rod 46, and thereafter, the clamps are shifted and the workpiece or sickle is again put in place in the clamps so that the work may be moved through the balance of the necessary range along the grinding wheel.

It should be observed that when the wear of the grinding wheel results in improper grinding of the lower ends or roots of the teeth 261, this condition may be readily corrected by adjustment of the plate in a forward direction on the bed 21.

From the foregoing description it will be apparent that the present invention enables the grinding of sickles to be accomplished quickly and easily by an ordinary unskilled worker, and this is accomplished in such a way that the danger of damage to the sickle is avoided. It will also be evident that the present invention is of such a character that it simplifies the location of the work with respect to the grinding wheel, and the progress of the grinding operation may be readily checked in a simple and easy manner.

It will also be apparent that the present invention enables the sickle to be ground without the necessity for the operator to support the weight of the sickle, and under the present invention the necessary force between the grinding wheel and the sickle is automatically applied, in the present instance by gravity, so that the danger of breaking or otherwise damaging the sickle is avoided.

It will also be evident that the present sickle grinder is of particular utility in that the user may, when an ordinary grinding operation is to be performed, remove the belt 87 so that the grinding wheel shaft will remain stationary at the desired elevation and the worker may then perform the desired conventional grinding operation.

Thus, while I have illustrated and described the preferred embodiment of my invention, it is to be understood that this is capable of variation and modification.

I claim:

A sickle grinder of the character described adapted for grinding the adjacent edges of adjacent teeth on a sickle, the combination of a supporting frame having an elongated horizontal front supporting bar and a parallel rear supporting bar spaced rearwardly from said front supporting bar, an elongated mounting rod mounted on and in upwardly spaced relation to said front bar, a pair of sickle clamps mounted on said rod for rocking movement on and about the horizontal axis of said rod and for free sliding movement throughout a substantial range longitudinally of said rod, a mounting plate mounted on and extended between said front and rear bars in a horizontal position for limited adjustment toward and away from said mounting rod, a rocking arm mounted on and above said mounting plate on a horizontal axis spaced a substantial distance rearwardly from said front support bar, a grinding wheel shaft rotatably mounted on the forward end of said rocking arm and having a grinding wheel fixed on one end thereof, such grinding wheel having a V-shaped working surface adapted for grinding the adjacent edges of adjacent sickle teeth, driving means mounted on the upper face of said mounting plate and having a driving connection with said grinding wheel shaft for constantly rotating said shaft and said grinding wheel, a gear housing extended downwardly from said plate and having a rotatable member therein, means affording an eccentric connection between said rotatable member and said rocking arm, and means including a driving belt Refgrences Cited in the file of this paxen-t UNlTED STATES PATENTS 567,638 Clizbe Sept. 15, 1896 623,683 Neuens et a1 Apr. 25, 1899 665,328 Johnston 5 Jan. 1, 1901 8 Neuens V 51111 24, 1-992 Nixon Apr 2 1.904 Pneuman May 10, 1904 Brown et a1. Apr. 4, 193,3 vBend-a July 18, 1-939 Rainbolt et a1. Sept. 27, 1949 Harrell Aug. 8, 1950 Rinne Jan. 15, 1952 'Webber Jan. 29, 1952

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