US2171604A - Cloth-cutting machine - Google Patents

Description

Sept. 5, 1939. s. SEGAL CLOTH-CUTTING MACHINE 3 Sheets-Sheet 1 Filed June 18, 1956 v z lNVENOR BY ATTORNEY h m m w Sept. 5, 1939. s. SEGAL 2,171,604

- CLOTH-CUTTING MACHINE Filed June 18, 1936 3 Sheets-Sheet 2 INVENTOR M I ATTORNEY Sept. 5, 1939.

s. SEGAL 2,171,604

CLOTH-CUTTING MACHINE Filed June 18, 1936 3 Sheets-Sheet 3 r A V WWW 62 I 1 W V30 V29 v ATTORNEY Patented Sept. 5, 1939 UNITED STATES PATENT OFFICE 9 Claims.

The present invention is a new and useful cloth cutting machine wherein a movable blade is sharpened by a pair of grinding wheels adapted to be oscillated for alternately impacting opposing faces of the blade to produce a relatively sharp and durable cutting edge. More particularly, however, the invention is concerned with a cloth cutting machine having a reciprocable blade and reciprocable and oscillatable means for sharpening the blade during its reciprocation within the holder or guard thereof.

It is an object of the invention, among others, to provide in a cloth cutting machine, sharpening means adapted to be swung forwardly of the cutting edge of the blade for alternately impacting during oscillation thereof opposing faces of the blade to form the desired cutting edge during reciprocation of the blade, and adapted to be conveniently and readily shifted or swung to the rear of the blade and away from its cutting edge pursuant to sharpening operations.

It is another object of the invention to provide an improved blade having a plurality of spaced teeth integrally interconnected by spaced reduced portions having relatively less resistance to wear during sharpening by the grinding wheels than the body of the blade.

It is a further object to provide a cloth cutting machine wherein a movably guided blade includes a plurality of teeth defining an irregular or toothed cutting edge and forming a plurality of spaced grooves in alinement with relatively reduced portions of the blade whereby during sharpening operations the grinding wheels straddling the blade cooperate with the irregular contour of cutting edge to maintain said contour.

It is a further object of the invention to provide in an improved cloth cutting machine means for adjusting and indexing the grinding wheels in respect to the cutting edge thereof preparatory to sharpening operations.

It is another object to provide a cloth cutting machine sharpening holding or supporting means conveniently adapted to be bodily removed from the cutting machine or readily applied thereto bodily.

Other objects, advantages and features of the invention are in part obvious and in part hereinafter more particularly set forth.

The present invention will be best understood from the following discussion of the several typical structural embodiments, reference being had to the accompanying drawings in which:

Fig. 1 is a side elevational view of the cloth cutting machine according to the invention,

shown partly in section and further illustrating in full lines the sharpening wheels disposed forwardly of the blade with the supporting carriage thereof in an unlocked position and having its rotatable shaft unlocked and adapted to be swung rearwardly of the blade in a clockwise direction as shown by the dash lines to arrange the sharpening wheels in back of the blade as indicated by the dash and dot lines.

Fig. 2 is a side view of my improved blade shown on a larger scale.

Fig. 3 is a sectional view on the line 3-3 of Fig. 2.

Fig. 4 is a sectional View on the line 44 of Fig. 2.

Fig. 5 is a front View of Fig. 1, shown partly broken away.

Fig. 6 is a sectional view on the line 6-6 of Fig. 1.

Fig. 7 is a fragmentary view of Fig. l illustrating the slidable carriage supporting the sharpening means unlocked and adapted to be reciprocated relative to the reciprocable blade.

Fig. 8 is a fragmentary view of Fig. 1 showing the slidable carriage in a locked position and the grinding wheels disposed at the rear of the blade.

Fig. 9 is a sectional view taken on the line 99 of Fig. 7, illustrating several positions of the oscillatable carriage and its grinding wheels in full and in dash and dot lines.

Fig. 10 is a sectional view on the line Ill-l0 of Fig. 9.

Fig. 11- is a fragmentary view illustrating a sharpening holding unit adapted to be bodily applied to or removed from the machine.

Fig. 12 is a sectional view on the line l2-I2 of Fig. 11. I

Fig. 13 is a fragmentary view of a cloth cutting machine according to the invention illustrating a modified means for oscillating a sharpening supporting carriage of the type disclosed in connection with the form shown in Figs. 1-1() inclusive.

Fig. 14 is a sectional view on the line [4-44 of Fig. 13.

Fig. 15 is a fragmentary side view of a cloth cutting machine showing a modified sharpening holding unit bodily removable from the guard and base of the machine.

Fig. 16 is a sectional View on the line l6-l6 of Fi 15.

Fig. 17 shows a blade according to the invention for use in connection with a cloth cutting machine adapted to use a circular blade and Fig. 18 is a sectional view along the line I8-l 8 of Fig. 1'1.

The cloth cutting machine is generally designated l0 and comprises the usual base ll, upstanding knife guard l2 from which the rearwardly disposed platform of arm I3 extends and on which depending lug l4 of the electric motor or prime mover casing I5 is appropriately secured. Shaft I6 of the motor rotates the relatively heavy crank l1 eccentrically actuating connecting rod I8 which in turn has its closed and looped end loosely associated with wrist pin IQ of the cross head 20 vertically and slidably guided in a raceway formed by the spaced tracks 2| and 22. By the present arrangement rotary motion of shaft 13 is translated into reciprocating motion.

Cross head 20 carries a clamping plate 24 (see Fig. 6) which may be controlled by 'a nut 25 threaded on bolt 26. The upper bifurcated portion 21 of blade 28 straddles the shank of bolt 25 and is secured against the crosshead by the clamping plate 24 under the influence of nut 26 as is well understood. The body of the blade 28, however, is vertically guided between a pair of relatively thin leaves 29 secured to the spaced sides of the knife guard l2; It follows therefore that during rotation of shaft IS, the blade is reciprocated vertically in the .relatively narrow throat or channel formed by the spacedleaves secured to knife guard l2.

In actual practice, it is desired to sharpen the blade Without removing the latter from the guard. According to the invention this function may be conveniently accomplished by a pair of grinding'or sharpening wheels 30 which may be shifted to straddle the blade. These wheels alternately impact opposing faces of the blade during reciprocation of the latter. Each of the sharpening wheels is rotatably mounted on the shank of a vertical rivet 3| fastened to a pair of vertically spaced extensions 32 of a fork 33 having a cylindricalspindle 34 slidably and adjustably mounted in a bushing or sleeve 35. More particularly a clamping set screw 36 is utilized to hold a spindle 34 in an adjusted and set position in respect to its associated bushing 35.

Bushings 35 may be said toconstitute spaced arms straddling central block 31 with which they constitute for purposes of specification a vertically shiftable and rotatable or oscillatable yoke or carriage generally denoted 38. One arm 35 of this carriage is permanently fixed to an overhanging portion 39 of the transversely disposed shaft 48 rotatably and slidably mounted within bore 4! of block 31, that is, eye 42 of the fixed arm is permanently secured to overhanging portion 39 of shaft 40. Eye 42, however, is provided with a laterally extending 'fingergripp-ing member 43, which if manipulated under certain conditions may be utilized to slide and rotate shaft 40 relative to block 31. V

The other arm or bushing 35 of sharpening supporting carriage 38 is slidably mounted on the overhanging portion 44 of shaft 40. Particularly, however, eye or strap 45 of this arm maybe rectilinearly and slidably displaced relative to shaft 48 although non-rotatably mounted thereon by reason of the key. effect formed by the mutual contacting rectilinear faces 46 and 41 of the overhanging shaft portion 44 and eye 45 respectively.

Eye 45 of the slidable arm of the carriage is provided with a laterally projecting hollow rim or finger gripping housing 48 in which the terminal 49 of overhanging portion 44 of shaft 4! extends. Helicoidal spring 58 surrounds terminal 49 and has one end abutting the annulai and inner shoulder 5| of the housing 48 am another end abutting an annular shoulder formec' by ring 53 removably retained against the em face of terminal 49 by the threaded and adjustable set screw 54.

The normal action of spring 50 is such as t( urge and set eyes 42 and 45 against companior rectilinear side faces 55 of the central block 31 provided of course locking detent 56 of eye 42 of the fixed arm 35 is locked within either of the cooperating recesses or indentations 51 and 69 In such locking relation shaft 48 is preventec' from rotation about its longitudinal axis relative to block 31. In the position illustrated in Fig, 9 the fixed and movable arms 35 extend forwardly of block 31 to straddle the guard and the locking detent 51 of eye 42 is within indent 51 of block 31. Therefore shaft 40 cannot be rotated relative to block 31. In such relation, however, carriage 38 may be slidably and vertically displaced along a vertical cylindrical guide and fulcrum post 8! fixedly interposed between base H and the overhanging platform l3. More particularly fixec' post 60 slidably guides vertical displacement oi carriage 38 by reason of a cylindrical sleeve 01 bearing 6| closely but loosely and concentrically surrounding post 68, which sleeve 6| is fixed tc and depends from central block 31 of the carriage 38.

It will be noted that sleeve 6! extends withir bore 62 of block 31 and is provided with a semicircular cut out groove portion 63 while the central part of shaft 48 is provided with a reducec' portion 64 forming groove 65 which in part receives and interlocks with post thereby preventing rotation of shaft 48 about its horizontai axis, that is, as illustrated in Figs. '1 and 8 shaf 48 cannot be rotated relative to its carriage 38 although sleeve 5| may be manually swiveled or partially rotated horizontally to correspondingly oscillate the carriage and thus displace the spaced grinding wheels 30 to alternately impact the sides of the blade and form the desired sharpening edge. In other words, carriage 38 may be slidably guided along post 60 and simultaneously the sharpening wheels carried by arms of the carriage may be severally moved into and out of contact with the forward vertical edge of the blade during reciprocation of the latter even though shaft 4i] is locked against rotation about its longitudinal axis since in effect fulcrum post 60 in part is received by groove 65, thus forming a pivoted or swiveled connection.

With sharpening operation concluded, carriage 38 is moved to the upper part of the guard until reduced portion 84 of shaft 48 is in alinement with an attenuated portion 66 of post 68. Thus shaft 48 is disconnected from fulcrum post 88. Thereafter manipulator 43 is grasped and moved outwardly. Therefore two important functions take place. First, shaft 40 is slidably displaced relative to block 31 against the normal action of spring 5|. Second, .locking projection or detent 56 is moved out of indent 51. If therefore manipulator 43 is rotated, shaft 48 is rotated relative to block 31 and the reduced portion 84 of shaft 40 (see Fig. 8) enters groove 61 formed by the attenuated part 66 and interlocks with the latter.

With grinding wheels 30 in the full line position shown in Fig. 1, and shaft 40 set to be free of post 60, shaft 40 may be rotated clockwise by actuating manipulating member 43. Thus arms i of the carriage are swung downwardly and arwardly towards the rear of the guard 12 until atent 56 is in alinement with recess or indent 69 L block 31 at which time manual pressure is eleased from manipulator 43 and the action of re spring 5| automatically forces shaft 40 to ide relative to the central block whereby detent i enters and interlocks with indent'69 of block I provided reduced part of shaft 40 is intercked with the walls of groove 61 as shown in lg. 8, that is, the arms of the carriage may be vung away from the sides of the guard and in tck of the blade to be in an ineffective position ."iderneath platform l3. Thus the grinding heels are disposed rearwardly of the guard and. a not straddle the sides of the latter. In this [effective position of the grinding Wheels, carage 38 cannot be vertically displaced relative to 3st 66 since the reduced portion 64 of shaft 40 interlocked with the walls defined by groove 61 ad seated on lower stop shoulder 68 formed by re latter.

When shaft 16 of the prime mover is rotating, fade 28 is reciprccably guided. Even during this aeration, the grinding wheels may be thrown om the set and ineffective position indicated by re dash and dot lines in Fig. 1 to their full line effective position. In this connection, finger ripping member 43 is first moved outwardly to isconnect fixed arm 35 from block 31. Subseuently finger gripping member 43 is rotated to )tate shaft 40 counterclockwise. Therefore rms 35 of the carriage are moved downwardly, ien upwardly, until they assume a horizontal osition straddling the sides of the knife guard 2. In this position detent 56 registers with inent 51. Finger pressure is now released from ranipulator 43 and detent 56 automatically enars indent 51. Hence arms 35 are locked and innot rotate relative to the pivoted block 31.

With arms 35 straddling the knife guard and icked against rotation block 3'! of the sharpen- 1g supporting means or carriage 38, however, lay be reciprocably guided relatively along guide st 66, that is, block 31 is now unlocked and ray be moved up and down vertically. However, 1 the unlocked position of block 31 the latter ray also be swiveled or rotated relative to post 0, thus causing sharpening wheels 3| carried by rrns 35 to alternately impact opposing faces of ne blade or knife during reciprocation of the ttter. During such contact the grinding wheels re rotated by the reciprocating blade and durig sharpening periods the carriage is manually ocked or swiveled about guide post 66 and at be same time may be moved vertically there long.

As previously pointed out one of the chief dvantages of the invention resides in the proviion of sharpening means which may be quickly rranged on front of the blade to sharpen the ttter and pursuant to such operation the sharpning means may be quickly shifted to be at the ack of the blade and out of the way. In Fig. 8 he sharpening wheels are at the top of the guard nd in back thereof. In such position the cariage is prevented from downward displacement lnce reduced portion 64 of the slidable and roatable shaft 46 is confined in recesses 61. In uch relation the arms of the carriage are locked Iith the oscillatable block 31. Even though rinding wheels are in back of the blade lateral ,isplacement thereof is limited by lips 35 strikig guard l2.

With the carriage in the position illustrated in Fig. 8, the grinding wheels may be quickly shifted or swung to the front of the blade. In this connection, manipulator 43 is grasped and moved outwardly. Consequently detent 56 is removed from indent 69 and shaft 40 is slidably moved transversely relative block 37. Hence spring 5| is compressed. Since shaft 46 is now free to rotate, the knurled head 43 is rotatably manipulated, thus swinging arms 35 to dispose the grinding wheels in the front of the blade until indent 56 is in alinement with indent 51 at which time the manipulator 43 is released and as a result of the expansion of spring 5| shaft 40 is caused to slide inwardly relative to block or member 31'. Consequently groove 65 is now side by side groove 51 of the attenuated portion 66. Therefore the carriage is released from lower shoulder 68 and now may be slidably moved along post 60. At this time, also indent 51 receives detent 56. Therefore arms 35 are prevented from rotation relative to the slidable and rotatable block 31.

It will be noted that the opposite parts of the reduced portion 64 of shaft 40 has several functions. When the grinding wheels are at the front of ,Ithe blade groove 65 in part receives post 66 (Fig. 9) and hence a pivotal connection is formed with fulcrum post 60. With the arms 35 at the rear of the guard reduced portion 64 is confined within groove 61, thus cooperating to prevent vertical displacement of the carriage. With the present construction it will be apparent that if the grinding wheels are at the front of the blade, they can be shifted to the rear of the guard provided the carriage is first moved upwardly to the top of the guard so that grooves 65 and 6! are in communication at which time shaft 40 may be rotated provided detent 56 is out of indent 57.

In actual practice, one of the grinding wheels may wear at a faster rate than the other. Consequently the character of the knife edge obtained during the process of sharpening is varied. With the present invention means has been provided to control the relation of the grinding wheels in respect to the blade to obtain a substantially uniform type of edge even though the grinding wheels may wear at different rates. In this connection the upper extension 32 of each of the forks 33 is provided with a pointed index or tapered projection H. These projections are set to be disposed in alinement with the feathered edge of the blade by means of an index line 12 ground into the upper surface of each wheel. Hence the grinding or sharpening wheels strike the beveled faces 13 of the blade at the proper angle to form the desired cutting edge. In case where one of the grinding Wheels does not properly strike the adjacent beveled face of the blade, its spindle 34 may be slidably adjusted relative to its arm 35 and subsequently clamped in the set position by set screw 36.

According to the invention the blade is provided with a sinuous or irregular edge 15. The edge is maintained during the course of sharpening by reducing the body of the blade. In this connection, it will be observed that in effect the blade comprises a plurality of spaced teeth 16 forming grooves Tl each in horizontal alinement with opposed recesses 18 to characterize a reduced or attenuated portion 19 in the body of the blade. By reason of such construction the reduced portions of the blade are slightly weaker than the body of the latter and consequently wear more readily during sharpening operations and thus the toothed effect of the irregular or tortuous cutting edge is maintained during the process of sharpening and during such operations vertical movement of the carriage 38 islimited by lug 88 projecting from guard I2 during the upward stroke of the carriage and by the depending guide sleeve 6 I' abutting base I I on the downward stroke of the carriage.

A stack of cloth 8| is placed on the forward part of base II and a forked presser foot 82 holds the cloth in a set position. The presser foot is carried by a square rod 83 slidably guided in grooved and spaced shoes or tracks 84 secured to the offset plate85 having its side wall 86 fixedly fastened to lug I4 depending from the casing of motor I5. A brake latch 87 has a square guide hole 81 at one of its ends for receiving the square rod 83 and has another end loosely disposed between a pair of posts 88 projecting rearwardly of the front cover plate 89.

Latch 81 is actuated by pivoted lever 90. Specifically, however, lever 98 is pivoted to closure plate 89 by set screw 9! and is provided with an offset lug 92 disposed in gap 93 (Fig. 5) formed by the bifurcated portion 94 of the manipulatable lever 95 (Fig. 1) which has an intermediate portion thereof pivoted on the set screw 96 adjustably fastened to lip 91 of closure plate 89 which in turn is secured to shoes 84 by set screws 84.

When the manipulating portion 98 of lever 95 is moved in a direction towards depending lug I4 of the motor casing its bifurcated end 94 is moved outwardly, hence lever 98 is actuated and pivots on set screw 9|. Therefore bifurcated portion 99 which straddles the braking latch 81 is released and moves downwardly, that is, the sides of the squared opening become frictionally free of rod 83 and consequently the latter drops by gravity such that its presser foot rests upon the uppermost layer of the stack of cloth.

If finger pressure be removed from manipulating portion 98, resilient wired spring I88 automatically urges the latter outwardly, thereby tilting lever 98 in an opposite direction to assume an inclined position as shown in Fig. 5 whereby the inclined walls of the square hole 81' abut the sides of the square rod 83 and the latter is braked or held in a set position. Spring 1 881 has one end I8I fastened to lever 95, an intermediate portion I82 coiled about shank of set screw 96 and an offset end I83 fastened to the closure plate '89. With this arrangement, manipulating portion 98 is normally urged outwardly and consequently the brake latch is normally braced against rod 83 to hold the latter in a set position.

In the form according to Figs. 11 and 12, the oscillatable carriage 38 comprises diverging arms II8 and III each ofwhich is provided with an eye II2 interposed between annular flanges II3, I14 and H5. Flanges H3 and II4 are fixedly secured to the vertically disposed bearing I I6 having groove I I! the curved wall of which cooperates with the curved end II8 of guard I2 to define a removable swivel or pivotal connection permitting diverging arms II8 of the carriage to be horizontally swung towards and from the blade.

Annular flange H5 is a part of sleeve H9 and the hollow concentric nipple I28 projects upwardly from flange H5. Encircling nipple I28 are the spaced eyes I I2 of the diverging arms I I 8 and also encircling nipple I28 are the annular flanges I I3 and I I4 carried by the semi-circularly grooved shaped bearing I I6 of the carriage. The bores of flanges H3, H4 and H5 as well as bore of eyes I I2 are in vertical alinement as shown to permit insertion, if desired of a" guide post 68 of the type shown in Fig.- lwhere it is desired to guide the sharpening. supporting, means in tl manner shown in Fig. .1. In Figs. 11 and 12, t] sharpening supporting means may be considerl as a unit which may be conveniently applied the guard I2 and quickly removed therefrom. applied to the guard I2, it may be slidably a1 vertically displaced relative to guard I2 and the same time oscillated by holding bearing I against curved end II8 of the knife guard a1 motion to and fro transversely of the gua: whereby the grinding and sharpening wheels a ternately impact the blade during its recipr cation. In Figs. 11 and 12 each arm II 8 ca ries an adjustable clamping member I2I on Whit a fork 33 is slidably mounted. Each fork in Fig 11 and 12 is provided with a rearwardly di posed slotted extension I2I' slidably mounted the shank of clamping member I2I and rotatab carries the horizontally disposed grinding whee for cooperating with the reciprocating blade sharpen the edge of the latter.

In the form according to Figs. 13 and 14, ca riage 38 of the sharpening supporting means of the type disclosed in connection with Fig 1-10 but the central block 31 thereof is ve tically and slidably guided on a square post Ii having its ends I26 rotatably journalled in bea. ings I27 and I28 of the platform I3 and base I One end I26 of post I25 is fixedly connected an arm I29 which has an upstanding projectic I38 havingopening I3I confining one end of ar I32 having its eye shaped end I33 pivotally su. tained by shank of set screw I34. Arm I32 surrounded by spring I35 which acts to hold an I29 in a set position. In operation, finger gri ping members 43 and 48 are grasped and shim to and fro horizontally. Hence squared post I? is oscillated which in turn oscillates carriage 3 Consequently the grinding wheels straddling t1 blade alternately impact opposing faces therec During such operation, however, carriage 38 me be slidably and vertically moved along the guir post I25. In other aspects, the form illustrate in Figs. 13 and 14 is along the lines of Figs, to 8 inclusive.

According to the form shown in Figs. 15 at 16 the sharpening supporting means may be cor veniently applied to or disconnected from ti knife guard I2 and from the base of the m2 chine. In this connection the sharpening su porting means 38 is rotatably and slidabi mounted on post I48 attached to base plate I removably placed on base II. Carriage 38 ii cludes a depending knurled sleeve I42which su1 rounds post I48 and is slidable relative there1 for vertically displacing the grinding wheel During displacement of sleeve I42, the latter also rotated in one direction and subsequent in the opposite direction, thus causing the grim ing wheels to alternately impact opposing fact of the blade.

The sharpening supporting assembly unit 1 Figs. 15 and 16 although disconnectably assr ciated with guard I2 may in fact be removabj clamped thereto. For this purpose a pair I pivotally interconnected jaws I58 and I5I is pr( vicled. These jaws are pivotally mounted on fu crum pin I52 attached to base plate I 4|. Li; I53 of these jaws embrace guard I2 and a1 clamped thereto by adjusting set screw I54 whic if rotated in one direction causes ends I55 1 separate to bring lips I 53 towards each 0th and by which if rotated in an opposite directio lips I53 are caused to diverge and be free of ti guard and thus permitting base plate I4I togethc with its sharpening supporting carriage to be bodily removed from base I I by the aid of handle 156. In such event the entire sharpening assembly support is quickly removed from the base of the machine and the blade is free of the grinding wheels.

According to Figs. 17 and 18, a circular blade is illustrated. This type of blade is employed in connection with the so called rotary cloth cutting machine well known in the art. The blade illustrated in Fig. 17, however, differs from those heretofore utilized in connection with the rotary cutting machine in that its cutting edge is sinuous or irregular in contour to provide a plurality of circumferentially disposed and spaced teeth. This effect is maintained even during sharpening periods since the blade is provided with a plurality of spaced attenuated portions I60. In this instance, the attenuated portions are radially arranged and as in the case of the form shown in Fig. 2, are relatively weaker thanthe body of the blade and consequently wear more readily during grinding.

The blade illustrated in Figs. 2 and 17 present an edge having spaced teeth which in operation simulate the action of a saw. In passing through a stack of cloth this type of edge produces a relatively clean sharp out without tearing any of the layers of the stack, and in actual practice, this type of edge has been found to stand up for appreciable long operating periods even though subjected to relatively heavy duty.

With the grinding wheels 30 in position for sharpening as shown in Fig. 9, carriage 38 may be bodily rotated or oscillated to permit wheels 30 to impact the opposing sides of the edge of the blade. During each cycle each wheel contacts the blade due to the manual pressure applied to the carriage. Although each Wheel is held momentarily against the reciprocating blade, in actual practice, it has been discovered that undulating edge of the blade because of the irregular or interrupted contour has a tendency to vibrate the impacting grinding wheel even against the resistance of the manual pressure applied to the carriage and even though the impacting wheel is against the reciprocating blade. This principle it has been discovered not only has a tendency to increase the sharpness of the edge of the blade but it has been also found that the spaced attenuated portion 18 of the blade will wear more rapidly than the teeth 16 thereof and notwithstanding the fact the latter are sharpened, the undulating form of the cutting edge is maintained.

Without further analysis, the foregoing disclosure will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it to various applications Without omitting certain features, that from the standpoint of the prior art, fairly constitute the essential characteristics of the generic and specific aspects of the invention and therefore such adaptations should and are intended to be comprehended within the meaning and range of equivalency of the following claims.

I claim:

1. In combination, a guard for slidably holding a blade, means for reciprocating said blade, a carriage, means slidably guiding said carriage, pivotal mean for oscillating said carriage, sharpening means sustained by said carriage and adapted to be disposed at the front of said blade, means for shifting said sharpening means to be disposed at the rear of said blade, locking means toprevent displacement of said sharpening means to the rear of said blade when disposed at the front of said blade, locking means to prevent displacement of said sharpening means to the front of said blade when disposed at the rear of said blade, and means to prevent vertical displacement of said carriage when said sharpening means is disposed at the rear of said blade.

2. In combination with a movably guided blade, of a vertically guided carriage pivotally and transversely displaceable relative to said blade, sharpening means straddling said blade and carried by said carriage, means for swinging said sharp-ening means to dispose the latter from the rear to the front of said blade to permit the latter to be alternately impacted by said sharpening means during oscillation of said carriage, mean for slidably guiding said carriage when said sharpening means is disposed at the front of said blade, and locking means to prevent shifting of said sharpening means to the rear of said blade when the latter is disposed at the front of said blade.

3. In combination, a guard for movably guiding a blade, means for reciprocating said blade, a guide disposed rearwardly of said guard, a carriage having an intermediate portion slidably guided by said guide, a rotatable member carried by said portion, spaced arms mounted on said member, means carried by each of said arms for supporting a grinding wheel, locking means to prevent rotation of said arms and member relative to said intermediate portion, and a pivotal connection between said guide and member to permit swinging of said carriage in respect to said guard for alternately disposing said grinding wheels in contact with said blade during reciprocation thereof.

4. In combination, a guard for movably guiding a blade, means for reciprocating said blade, a guide disposed rearwardly of said guard, a carriage having an intermediate portion slidably guided by said guard, a rotatable shaft carried by said portion, an arm fixed to said shaft, a grinding wheel carried by said arm, an arm slidably and non-rotatably connected to said shaft, a grinding wheel carried by said slidable arm, and locking means to prevent rotation of said shaft and arms relative to said member during vertical displacement of said carriage relative to said guard, said grinding wheels straddling the forward portion of said blade during vertical reciprocation of said carriage, said guide having means to permit transverse displacement of said shaft relative to said carriage for releasing said locking means, said shaft upon releasing of said locking means being rotatable relative to said intermediate portion for moving said arms and grinding 'Wheels to the rear of said guard.

5. In combination, a guard for movably guiding a blade, means for reciprocating said blade, a guide disposed rearwardly of said guard, a member slidably mounted on said guide, a shaft slidably and rotatably carried by said member, an arm secured to said shaft, a grinding wheel carried by said arm, an arm slidably and nonrotatably mounted on said shaft, and a grinding wheel carried by said slidable arm, said shaft and guide having means constituting a pivotal connection to prevent sliding and rotation of said shaft relative to said member and permitting transverse displacement of said arms relative to said member, said shaft and guide having coop- 'ierating means to prevent displacement of said "member relative 'to said guide.

"6. In combination, a guard for movably guiding a blade, means for reciprocating said .blade, a guide disposed rearwardly of "said guard, a member slidably mounted on said guide, a shaft slidably and rotatably carried by said member, an arm secured to said shaft, a grinding wheel carried by said arm, an arm slidably and non-rotatably mounted on saidshaft, and a grinding wheel carried by said slidable arm, said shaft and guide having means constituting a pivotal connection to permit vertical displacement of said 'member and arms relative to said guide and to prevent rotational and lateral displacement of said shaft relative to said member for displacing said arms transversely of said member to alternately dispose said wheels in and out of contact with said blade.

'7. In combination, a guard for movably guiding a blade, means for reciprocating said blade,

'a guide disposed rearwardly of said guard,:a member slidably mounted on said guide, a 'shaft slidably and "rotatably carried by said member, an arm secured to said shaft, a grinding wheel carried by said arm, an arm slidably and nonrota'tably mounted on said shaft, a grinding wheel carried by said slidable arm, said shaft and guide having means constituting a pivotal connection to prevent displacement of said shaft relative to said member and permitting displacement of said arms to alternately dispose said wheels when disposed forwardly of-said guard,

in and out -of contact with said blade,- locking means to prevent rotation of said arms relative to said member when said wheels .are disposed forwardlyof said blade, said shaftand guide having means to permit rotation of said. shaft upon release of said locking means to permit rotation of said shaft relative to said member for positioning said arms rearwardly of said guard, and locking means to prevent rotation of said arms relative to said member when said arms are'posi'tioned at the rear of said guard.

8. In combination, a guard for movably guiding a blade, means for reciprocating said blade, a guide disposed rearwardly of said guard, a vertically displaceable member slidably mounted on said guide, a shaft slidably and rotatably'carried by said member, an arm secured to said shaft, a

rotatable grinding wheel carried by said arm, an

arm slidably and non-rotatably mounted on said shaft, a grindingwheel rotatably carried by said 'slidable arm, said shaft and guide having means constituting a pivotal connection to prevent 'lateral and rotational displacement of said shaft relative to said member and permitting transverse displacement of said arms relative to said member to alternately dispose said wheels when disposed forwardly of said guard in and out of contact with said blade,lockingme'ans to prevent rotation of said arms relative to said member when said wheels are disposed forwardly of said blade, said guide having means to permit rotation of said shaft relative to said member upon release of said locking means for positioning said arms rearwardly of said guard, and locking means to prevent rotation of said shaft when said arms are positioned at the rear of said guard, said shaft and guide having means to prevent downward displacement of said member when said arms are positioned to the rear of said guard.

9. In combination, a base having an upstanding guard, a removable support mounted on said base'and having anupstanding guide, pivoted means slidably mounted on said guide comprising arms removably straddling said guard, grinding wheels carried 'by said arms and adapted to impact opposing faces of said blade during oscillation of said pivoted means, and clamping means associated'with said support for removably embracing said' guard. 1

SAMUEL SEGAL.

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