US2529441A

US2529441A - Cloth-cutting machine

Info

Publication number: US2529441A
Application number: US15768A
Authority: US
Inventors: Zawistowski Martin
Original assignee: Individual
Current assignee: Individual
Priority date: 1948-03-19
Filing date: 1948-03-19
Publication date: 1950-11-07
Anticipated expiration: 1967-11-07

Description

Nov. 7, 1950 ZAWISTOWSKI CLOTH CUTTING MACHINE 4 Sheets-Sheet 1 Filed March 19, 1948 BYZ W Z ATTORNEY Nov. 7, 1950 M. ZAWISTOWSKI CLOTH CUTTING MACHINE 4 Sheets-Sheet 2 Filed March 19, 1948 INVENTOR Mafiiz'n/ zawzliz owsfi' BY M Z ATTORNEY NOV. 7, 1950 z w s ow5 2,529,441

CLOTH CUTTING MACHINE Filed March 19, 1948 4 Sheets-Sheet 3 45 I ATTORNEY Nov. 7, 1950 M. ZAWISTOWSK] 2,529,441

CLOTH CUTTING MACHINE Filed March 19, 1948 4 Sheets-Sheet 4 MBY7M W ATTORNEY Patented Nov. 7, 1950 UNITED STATES PATENT OFFICE 21 Claims.

This invention relates to cloth cutting machines of the reciprocating knife type, and more particularly to the means for sharpening the knife. In my prior Patents 2,282,917, 2,282,918, and 2,480,278, constructions are illustrated in which the knife sharpening members are a pair of grinder wheels or stones rotatably supported on arms pivotally mounted near the upper end of the knife. They are away from the knife when the grinders are not in use, but when knife sharpening is to be effected the grinders may be operatively connected to a source of power to rotate them, and the arms are swung to bring the grinders into engagement with the knife. The grinders move first down and then up along the blade to sharpen the cuttingedge, and the arms then swing to move the grinders away from the knife.

As one feature of my present improved construction I make unnecessary the use of a reversing gearing for rotating a feed screw first in one direction and then in the other to effect the up and down movement of the rotatable grinders. Instead of one screw and a reversing gearing I provide a pair of parallel rotatable screws and a member which may be moved into engagement with one of said screws at the upper end thereof to feed grinders downwardly. At the lower end of the down movement said member is automatically shifted to engage with the other screw to feed the grinders upwardly.

As a further feature, the feed mechanism is so constructed that at the end of the up movement of the grinders the feeder member disen-gages the thread of one screw but does not engage the thread of the other, and therefore the grinders are stopped in the upper position until the feeder member is again shifted. In the preferred form the thread of the up-feeding screw terminates below the upper end of the thread of the down-feeding screw, so that the up movement stops automatically when the feed member goes beyond the thread of one screw, and the down movement may be started by moving the feeder across to the other screw.

As a further feature, means are provided for positively holding the feeder member in operative engagement with one screw to effect the downward movement of the grinders, and then automatically shifting and holding it in operative engagement with the other screw during the up movement. Thus, it is necessary to move the feeder member only from one screw to the other,

and the grinders will start moving, complete a down movement, and then an up movement, and come to rest in the up position.

As a further feature, the movement of the feeder into engagement with the down-feeding screw and the starting of rotation of the screws, is effected substantially simultaneously, and by a single control member.

As a further feature, the grinders are operated by the same motor that reciprocates the knife.

As a further feature, friction drive means is provided for operatively connecting the grinders to the motor which operates the knife, and a manually operable member is provided for controlling this drive means.

As a further feature, the feeder member is automatically brought into engagement with the down-feeding screw upon bringing the friction drive into operation. Thus, by momentarily operating and then releasing the control member, the sharpener will start, go through one cycle, and then stop.

As a further feature, change speed gearing is provided, whereby the speed of up and down movement of the grinders, and therefore the time and amount of sharpen-action in a single cycle, may be varied.

As a further feature, means are provided where by the grinders may be locked in down position to give increased grinding along the lower end portion of the knife, if and when that is desired.

The invention also involves various other features which will be referred to in connection with for the presser foot being omitted, and showing the grinders part way along the down stroke.

Fig. 2 is a front view. Fig. 3 is a vertical section on the line 33 of Fig. l, and-in the rear of the feed screws.

Fig. 4 is a vertical section on the line 44 of Fig. l, and showing the driving means.

Fig. 5 is a vertical section on the line 5-5 of .Fig. 4.

Fig. 6 is a view similar to a portion of Fig. 2,

but showing the parts in the position they occupy when the grinders are at the upper end of their stroke.

Fig. '7 is a section on the line '!---1 of Fig. .6. Fig. 8 is a perspective view of certain of the operating parts, other parts being broken away,

. 3 and showing control means whereby the sharpeners may be temporarily locked in the down position.

Fig. 9 is a side view of a portion of Fig. 8, and

Figs. 10 and 11 are sections showing parts of Fig. 8 in different positions of operation.

In the machine illustrated, and which embodies my improved features, there is the usual base ID for supporting the machine on a table, and movable beneath the layers of cloth or other material to be out. This base has a standard H acting as a guide for the reciprocating knife l2 and as a support for a frame part I3 on which the motor 14 is mounted. The machine has the usual handles !5 and 15a, one for moving and guiding the machine and the other for lifting the machine, and adjacent to the handle 15 is the switch is for starting and stopping the motor. These parts as well as the operating connections between the motor and the reciprocating knife may be of standard construction, and embody no new features of the present invention.

In my improved construction, a plate part [3a of the frame is provided with upper and lower bearings and 2| for a pair of

parallel screw shafts

23 and 24 held against endwise movement and provided at the upper ends with

gears

25 and 26 engaging with a worm gear 21 for rotating them in opposite directions. This worm gear may be operatively connected'to the source of power 1 when it is desired to start the knife sharpening operation, as will be explained more fully hereinafter.

Telescoping with the

screws

23 and 24 and keyed thereto for rotation therewith, there are provided

shafts

23 and 29 which act to raise and lower, as well as rotate the grinders, and which cooperate with means for oscillating the grinders into and out of operative engagement with the knife. The means illustrated for operating the grinders from the shafts forms no novel part of the present invention, and is substantially the same as illustrated and claimed in my prior Patent 2,480,278. As illustrated, the shafts extend through sleeves journaled in and held against endwise movement in respect to a horizontal plate 30. These sleeves have helical gears 32 and 33 resting on the plate, and arms 3'! and 38 below the plate. When the shafts are at the upper end of the movement, the gears mesh with inclined teeth on

rack bars

35 and 36 on the frame, and the arms extend forwardly. As the shaft moves down, these rack bars rotate the gears 32 and 33 and swing the arms 3'! and 38 through about 180. The

grinder wheels

39 and 40 are journaled on these arms at the free ends thereof, and are driven by belts 4| extending around pulleys 42 keyed on the lower ends of the shafts, and pulleys 4-3 secured to the grinder wheels. The pulleys 42 are below the sleeves which carry the arms, and the helical gears are separated from said arms by' friction washers and held against endwise movement on the shaft by the arms and collars 44. Thus, as the shafts start rotating and moving downward, the grinders are swung through about 180 by the rack bars, and into engagement with the knife, and then the helical gears leave the ends of the rack bars. During the further downward movement of the shafts, the rotating grinders will follow down along the knife and be yieldingly pressed against the knife by the friction washers. During return movement they will follow along the knife until the helical gears again engage the rack bars 4 to swing the stones back through approximately As an important feature of the present invention the plate 30 on which the lower ends of the

shafts

28 and 29 are journaled, and which carries the grinders and the drive therefor, is rigidly secured to and moved up and down by a carrier bar or plate 45 slidably mounted in the frame. Thus, as the bar 45 moves up and down, as hereinafter explained, it will move the grinder stones up and down. At the beginning of the down stroke it will cause the grinders to swing into operative position by the action of the

rack bars

35 and 36, and in the final portion of the up stroke will swing them away from the knife.

As a further feature of my invention this plate or bar 45 carries a grinder feeding mechanism positioned between the two

screws

23 and 24 and movable to coact first with one screw to effect the downward movement, and then into engagement with the other screw to effect the upward movement of the bar 45 and the grinders carried by the

shafts

28 and 29 which are slidable in and driven by the screws. This bar or plate 45 may be retained and guided by any suitable means, as

for instance by having beveled edges held between and behind the edges of guides 46. The feeding mechanism includes a bar 41 transversely slidable on the bar or plate 45, and retained by guides 48 secured to the bar 45. The bar 41 has a feeder for the grinders and operatively engageable with the

screws

23 and 24 alternately. As shown, it has

journals

50 and 5| supporting a flanged roller 52, so that when the bar 41 is moved endwise in one direction the flanges on the roller 52 will engage the thread of one ofthe screws, and when moved in the opposite direction will engage the thread of the other screw. When the roller engages the screw 23 it will travel down along the screw and carry the bar 4! with it, and will move the grinders downwardly. When shifted to engage the other screw 24, it will move the grinders upwardly. As the flanged roller acts with the screws to feed the grinders up and down, it may be designated as a feeder for the grinders.

As another feature of the invention, the screw 24 has the upper end of the thread terminate below the upper end of the thread on the screw 23, as shown at 53 in Figs. 2 and 6, so that when the parts are in normal or rest position the feeder 52 is above the thread of the screw 24. Thus, even though the screws be rotating when the feeder 52 reaches the up position it will come to rest, and there will be no further up movement of the bar 45 and the grinders operativel connected thereto.

In the operation of these parts, so far as described, when the screws start to rotate, the member 52 is moved into engagement with the screw 23 to feed the grinders downwardly and swing them into engagement with the knife. At the end of the down stroke, the feeder is moved into engagement with the screw 24, and the grinders are moved up along the knife until the feeder 52 reaches the unthreaded part 53. The bar 41 may be held in this position by a spring pressed pin 54 on the frame part I3a. This pin has a rounded end which will snap into a hole 55 in the bar, as shown in Figs. 6 and 7.

A manually operated control member is employed to start the rotation of the screws and to substantially simultaneously shift the bar 41 to engage the feeder 52 with the screw 23, so that the grinders are moved down the knife. At the lower end of the grinding stroke the bar 41 is automatically shifted to bring the feeder into engagement with the screw 24. This shifting is effected by a spring 56 mounted on a stud 51 on the guide 48 carried by the vertically movable carrier bar andngaging the bearing 5| of the feeder 52. Shifting of the feeder during the up and down stroke is prevented, as will be later explained.

As a further important feature of my invention there is provided means for simultaneously starting rotation of the worm wheel 21 by the motor and shifting the grinder feeder 52 into engagement with the screw 23. This includes a control lever 60 pivoted. on the side of the frame, and having an arm 6! operatively connected to the bar 41 when the latter is in its upper position, so that by depressing the end of the lever 69 the bar Ail is moved from the positions shown in Figs. 6 and '7 to the position shown in solid lines in Fig. 4.

The bar 4'5, as shown in Figs. 4 and 7, has a vertically disposed groove 62 in its outer end portion, and into which extends a pin 63 of the bell crank arm 5| of the lever 60 when the

bars

45 and 41 are in their uppermost position. Thus, in moving the lever from the position shown in dotted lines in Fig. 4 to the position shown in solid lines, the bar 47 is pulled endwise, and moves the feeder 52 into the screw 23.

As the bar 4'! is pulled endwise toward the right, the screws start rotating as hereinafter described, and the feeder member 52 is moved from the position shown in Figs. 7 and 6 into engagement with the screw 23, as shown in Figs. 2 and 3, so that the

bars

45 and 41 will start moving downwardly as the feeder 52 is carried down along the rotating screw 23. As above described, this carries the grinders and the drive thereto downwardly along the knife.

Extending vertically on the frame of the machine is a guide bar 64 provided in the rear edge with two notches, recesses or

gaps

65 and 65, as shown in Fig. 1, and the carrier bar 4'! has a flange 61 which ma move through the notches and engage either side of this bar. By depressing the lever the bar 41 is pulled endwise and the flange 5'! moves out through the upper notch to the outer side of the bar 64, and against the action of the spring 56. The downward movement of the bar 4! starts as soon as the feeder wheel 52 engages the screw 23, and as the flange 57 on the bar 47 has passed through the notch 55, said flange will ride along the outer surface of bar 64 and prevent return movement of the bar 4? and the feeder. Thus the feeder is held in engagement with the screw 23 during the down movement.

When the bar Ill reaches the lower end of its path of movement, the flange 61 reaches the lower notch 85, and the spring 56 will force the bar 4? endwise in the opposite direction to carry the feeder 52 away from the screw 23 into engagement with the screw 24. The bar 41 will then move upwardly until the flange 6! reaches the notch 55 and the feeder wheel 52 reaches the portion of the screw 24 above the end of the thread thereof, so that the up movement of the bar 45 and the parts carried thereby terminates.

When the vertically movable carrier bar 45 and the grinders carried thereby starts its down movement, the horizontally movable bar 41 will be in the outward position shown in Fig. 4, and the groove 62 in said bar 41 will almost immediately move out of engagement with the spring pressed pin 63 on the lever arm 6| of the con-' 6 trol lever; but as previously noted, the spring 56 moves the bar 4'!- back to its in-position at the'lower end of the stroke. The re-engagement of the pin 63 with the groove "52 of the bar 41 will be explained later.

For rotation of the

screws

23 and 24 when the feeder is shifted, the arm 6! of the control lever is connected by a link or pull rod H! to a gear carrying arm 1| having a sleeve 12 journaled on shaft 13, which latter is journaled in a bearing sleeve [3b carried by the frame-part [3a. This shaft 13 carries the worm gear 21 and has a pairo-f pinions l4 and l5'of different sizes. Rotatably mounted on a stud 16 carried by the arm H are a pair of gears 11 and 18, also of different sizes. The gear 1'! meshes with a gear '39 secured to a friction wheel 8B'rotatab1y mounted on the end portion of the arm. H. Thus, when the control lever 60 is moved from the dotted line position shown in Fig. 4 to the solid line position, 'the link or pull rod 10 .is pulled to swing the arm H on its pivot and to bring the friction wheel into engagement with a friction wheel 8| driven by the motor. The degree of friction may be controlled by adjusting the pressure of a spring 82 on the link :0, and between an adjustable stop 83 on the end of the link and a shoulder on the arm ll. When the control lever 60 is depressed to pull, the bar 41 endwise, the link 10 is pulled endwise and the spring 82 is compressedto yieldingly force the friction wheel 8!] into engagement with the friction wheel 8 I. Thus, power from the motor may be transmitted through the friction-wheel, the gears and the shaft 13 to rotate the worm 2! when the control lever is depressed.

The speed of the worm gear 21 which rotates the screws may be adjusted by moving the gears or pinions l4 and 15 endwise. As shown, the gear 15 is larger than the gear 14, and meshes with the gear 18, which is smaller than the gear H. The gears 15 and 18 are shown in mesh, but by moving the

gears

14 and 15 endwise, the gear 15 is moved out of mesh and the gear 14 is moved into mesh with gear TI; and the worm 2! will be rotated at higher speed with respect to the speed of the motor. The

gears

14 and 75 may be held in either of the two positions by a spring pressed ball 84 which may enter either of two depressions in the shaft 13.

Means are provided which make it unnecessary to hold the lever 6!] down during the grinding operation, and which will stop the grinding after the grinders make a complete down and up stroke. As shown, the control lever 60 is provided with an arm 85 having a catch 86 engaging a hook or lever retainer 81 slidable in the plate part 130. of the frame. In the path of movement of the, vertically movable grinder carrying bar 45 there is mounted a leaf spring 88, to the upper end of which the hook 81 is secured. The carrier bar 45 in its upper limitingposition, engages the spring 88 and holds the hook in the position shown in dotted lines in Fig. 5, with the end of the hook spaced from the frame plate l3a. The lever arm 85 is normally below the hook 81, as shown in dotted lines in Fig. 4. By depressing the leverEO, thereby to bring the friction wheel 80 into engagement with the friction wheel 8| and start the machine in operation, the arm 85 moves, from the, position shown in solid lines in Fig. 4, and the catch is moved above the hook. If desired, the upper edge of the lever arm 85 and the lower sideof the hook may be beveled, as shown in Fig. 5,

.t faid in guiding the catch up above the hook. As the carrier bar 45 starts down, it releases the spring 88, and hook 81 is held in the position shown in solid lines in Fig. 5, and the arm 85 will be locked in raised position. Thus the link or pull rod will continue to hold the friction Wheel 86 in engagement with the friction wheel 8|. When the grinding cycle is completed and the bar 45 again engages the spring 88, it will push the hook 8'! inwardly and let the lever arm 85 swing down, so that the link 10 lets the friction wheel 80 move away from the friction wheel 81v and the control lever 60 is free to return tothe position shown in dotted lines in Fig. 4. At substantially the same time, the flange 61 which was traveling along one side of the guide bar .64, reaches the upper notch 65, and the feeder 52 leaves the thread of screw 24 to end the cycle.

The outer end surface of the bar 41 is preferably slightly curved or inclined so that when said bar almost reaches the notch 65 it may engage the inclined end of the pin 63 and force it back against the spring 69, so that it may snap into the groove 62. Thus, when the bar 4'! is almost instantly thereafter released at the notch 65, the sliding movement of the bar will pull the control lever back to starting position and positively lift the friction wheel 80 off the friction wheel 8| and stop rotation of the screws.

In most cloth cutting machines of the reciprocating knife type; the knife I2 is rapidly reciprocated during the grinding action, and the lower end portion of the edge of the knife does not become ground away as much as does the mid-portion, and there is a tendency of the cutting edge to become somewhat concave. As an important feature of my invention means may be provided whereby the operator may occasionally retain the grinders in the down position for a short period of time after completing a down stroke and before beginning the up stroke. Thus, additional grinding is effected on the lower end portion of the knife, and the edge thus maintained straight. In the construction above described, the feeder member 52 at the lower end of the stroke suddenly moves from the dotted line position shown in Fig. 7 to the solid line position, and the up movement begins immediately when the flange 61 on the cross bar 41 which had slid down one side of the guide bar 64 with the feeder 52 in engagement with the screw 23, moves to the other side of the guide bar.

As a further feature of my invention, means may be provided which, at the end of the down stroke, will stop the horizontal sliding movement of the bar 4'! midway in its path of movement, and thus hold the feeder midway between the screws. This may be accomplished by a stop, which may be manually moved into and out of operation at will. This stop may be on the frame plate |3a in the path of movement of the end of the sliding member 41, or may be in the path of movement of the flange 61 on said member. In Figs. 8 to 11 I have shown such a stop in connection with the guide bar 64, and have shown the latter at the opposite side of the machine, as it, may be at either side. 7

The, stop means is shown as a latch 90 pivoted on the side of the guide bar 64 adjacent to the lower notch 66. The stop is shown in Fig. 8 in the inoperative position, and any suitable means may be employed for moving the stop into and out of operative position. As shown, it is mounted on a pivot pin 9|, and an end portion of the stop has a slot receiving the end of a lever 92 secured to a rock shaft 93 'journaled on the frame adjacent to the lower bearing 2! of the screws. At one end of the rock shaft there is a manually operable control member shown as a lever.94, and a spring 95 normally holds the lever in down position with the stop out of operation. By lifting the lever, the stop is moved over the notch 66 so that when the grinders get to the lower end of their path of movement the flange can pass into the notch, but cannot pass through. Thus the bar 41 will be stopped in mid-position, as shown in Fig. 11, and the feeder will be free of both screws. The grinders will remain in the down position, and only the lower part of the knife will reciprocate therebetween. After a short grinding period the stop may be moved away from the notch 66, the spring 56 will force the bar 41 to the end of its stroke to engage the feeder with the upfeeding screw 24, and the grinder will make its up stroke.

In the form shown in Figs. 4, 5 and 6, the pin 63 of the control lever enters a groove 62 in the bar 47, but other connecting means may be employed. In Figs. 8, 10 and 11 the bar 4'! is shown as having a hole 62a, which serves the same purpose as the groove 62.

Various other means might be designed within the scope of my invention for holding the grinders at the lower end of the stroke for a short period before the up movement begins.

It will be understood that in practice the screws and feeder may be concealed and protected in a manner common in this art, and that the usual presser foot is employed. The presser foot 9'! and its supporting bar 98 are shown in Figs. 1 and 2, and the lever 99 for operating the clamp l 66 to hold the presser foot in elevated position is indicated at the left of Figs. 2 and 3. As these parts form no portion of the invention they need not be described in detail.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. In a cloth cutting machine of the reciprocating knife type, a pair of vertically disposed parallel rotatable screws, a motor for simultaneously rotating said screws, shafts for rotating said sharpening elements, said shafts being concentric with, keyed to, and longitudinally movable with respect to said screws, a vertically movable member, knife sharpening elements carried by said member, a member carried by and transversely movable on said first mentioned member for operative engagement with one of said screws to move said sharpening elements downwardly along the knife, and operatively engageable with said other screw for moving said sharpening elements upwardly along the knife.

2. In a cloth cutting machine of the motor driven reciprocating knife type, a pair of vertically disposed parallel rotatable screws connected for simultaneous rotation, a vertically slidable bar parallel to said screws, shafts concentric with, keyed to, and longitudinally movable with respect to said screws, grinders operatively connected to and driven by said shafts, and means for moving said shafts and grinders endwise in respect to said screws, said means including a member transversely movable on said bar and having a part for engaging one screw to effect downward movement of said shafts and grinders and for engaging the other of said screws for g I effecting upward movement of said shafts and grinders.

3. In a cloth cutting machine of the motor driven reciprocating knife type, a pair of vertically disposed parallel rotatable screws, means for simultaneously rotating said screws, a vertically movable member, grinders carried thereby, a transversely movable member on said first mentioned member and having a part for engaging said screws alternately to effect up and down movement of said first mentioned member and said grinders, and a vertical guide bar for holding said transversely movable member against movement in respect to said vertically movable member, except at the upper and lower ends of the vertical movement of said first mentioned member.

4. In a cloth cutting machine of the motor driven reciprocating knife type, a pair of vertically disposed parallel rotatable screws, means for simultaneously rotating said screws and reciprocating the knife, a vertically movable member, grinders carried thereby, a transversely movable member on said first-mentioned member and having a part for engaging said screws alternately to effect up and down movement of said first mentioned member and said grinders, a vertical guide bar, a flange on said transversely movable member for engaging one side of said guide bar during down movement and engaging the other side during up movement, manually operable means for shifting said transversely movable member in one direction to engage one screw, and means for automatically shifting said member to effect engagement with the other screw at the lower end of the stroke to effect up movement.

5. In a cloth cutting machine of the motor driven reciprocating knife type, knife sharpening members, a pair of vertically disposed parallel rotatable screws, a member movable transversely into engagement with either screw and operatively connected to said sharpening members, means for simultaneously starting rotation of said screws and moving said member into engagement with one screw to effect movement of said sharpening members in one direction, means for shifting said member in the reverse direction to engage the other screw when said sharpening members are in lowermost position, and means for automatically stopping rotation of said screws when said sharpening elements reach the upper end of their stroke.

6. In a cloth cutting machine of the motor driven reciprocating knife type, knife sharpening elements, a vertically reciprocating member carrying said elements, a pair of vertically disposed rotatable screws geared together for simultaneous rotation, the thread at the upper end of one screw terminating below the upper end of the thread on the other screw, a feed member normally engaging the first mentioned screw above the thread thereof, means for moving said member into engagement with the other screw to effect downward movement of the sharpening elements, means for shifting it into engagement with the other screw at the lower portion of said screw to effect the upward movement of said sharpening elements, said upward movement terminating when said member passes beyond the thread of the first mentioned screw.

'7. In a cloth cutting machine of the motor driven reciprocating knife type, sharpening elements, a pair of vertically disposed parallel screws, a feed member for engaging one screw to effect downward movement of said sharpening elements and for engaging the other screw at the lower end of the stroke to effect upward movement of said sharpening elements, a manually operable control member, means operated thereby'for simultaneously effecting the starting of rotation of said screws and the engagement of said feed member with one screw, means for automatically shifting said feed member into engagement with the other screw at the lower end of the stroke of said sharpening elements, and means for stopping the rotation of said screws when said feed element reaches the limit of its upward movement.

8. In a cloth cutting machine of the motor driven reciprocating knife type, sharpening elements, a pair of vertically disposed parallel screws, a feed member for engaging one screw to effect downward movement of said sharpening elements and for engaging the other screw at the lower end of the stroke to effect upward movement of said sharpening elements, a manually operable control member, means operated thereby for simultaneously effecting the starting of rotation of said screws and the engagement of said feed member with one screw, means for automatically shifting said feed member into engagement with the other screw at the lower end of the stroke of said sharpening elements, means for stopping the rotation of said screws when said feed element reaches the limit of its upward movement, means for locking said control member against return movement after said manual operation thereof, and means for releasing said locking means when said feed member reaches its upper limit of movement.

9. A cloth cutting machine of the type having a knife, a motor for reciprocating said knife, grinders for sharpening said knife, means'for moving said grinders up and down along said knife, and means for rotating said grinders, said machine being characterized by a friction wheel driven by said motor, a friction wheel for effecting rotation of said grinders and the reciprocation thereof along the knife, and a manually 0perable member for moving saidsecond mentioned friction wheel into engagement with said first mentioned friction wheel, and substantially simultaneously operatively connecting said second mentioned friction wheel'to said grinders to effect rotation and reciprocation of the latter.

10. A machine as defined in claim 9, and in which there is provided means for locking said member after manual operation and means for unlocking it after a down and up movement of the grinders along the knife.

11. In a cloth cutting machine of the motor driven reciprocating knife type, knife sharpening elements, a pair of motor driven vertically disposed parallel screws, a member movable transversely into engagement with said screws alternately, whereby when engaging one screw said member is moved downwardly, and while engaging the other screw is moved upwardly, said knife sharpening elements being operatively connected to said member and moved up and down by said member for sharpening the knife, andmanually operable means for substantially simultaneously operatively connecting said screws to the knife reciprocating motor and shifting said member into engagement with one of said screws.

12. In a cloth cutting machine of the motor driven reciprocating knife type, knife sharpening elements, a pair of motor driven vertically disposed parallel screws, a member movable transversely into engagement with said screws alternately, whereby when engaging one screw said member is moved downwardly, and while engaging the other screw is moved upwardly, said knife sharpening elements being operatively connected to said member and moved up and down by said member for sharpening the knife, manually operable means for substantially simultaneously operatively connecting said screws to the knife reciprocating motor and shifting said member into engagement with one of said screws, and means for automatically shifting said member into engagement with the other screw at the end of the down movement.

13. In a cloth cutting machine of the motor driven reciprocating knife type, knife sharpening elements, a pair of motor driven vertically disposed parallel screws, 2. member movable transversely into engagement with said screws alternately, whereby when engaging one screw said member is moved downwardly, and while engaging the other screw is moved upwardly, said knife sharpening elements being operatively connected to said member and moved up and down by said member for sharpening the knife, manually operable means for substantially simultaneously operatively connecting said screws to the knife reciprocating motor and shifting said member into engagement with one of said screws, and means for locking said member in one position during down movement and in the other position during the up movement.

14. In a cloth cutting machine of the motor driven reciprocating knife type, knife sharpening elements, a pair of motor driven vertically disposed parallel screws, a member movable transversely into engagement with said screws alternately, whereby when engaging one screw said member is moved downwardly, and while engaging the other screw is moved upwardly, said knife sharpening elements being operatively con-' nected to said member and moved up and down by said member for sharpening'the knife, a guide parallel to said screws, and means on said mem ber for engaging said guide to prevent transverse movement of said. member during downwardand upward movement thereof, but permitting transverse movement at the ends of said movements.'

15. A cloth cutting machine having a motor driven reciprocating knife, a sharpening grinder for said knife, means operatively connectable to said motor for moving said grinder 'up and down said knife while the latter is reciprocating, means for retaining said grinder in its down position to effect additional grinding of the lower end portion of the knife, and manually operable means for moving said retaining means into and out of operative position.

16. In a cloth cutting machine of the motor driven reciprocating knife type, knife sharpening elements, a pair of motor driven vertically disposed parallel screws, a member movable trainsversely into engagement with said screws alternately, whereby when engaging one screw said tosaid member and moved up and down by said 7 member. for sharpening the knife, and means operable at will for holding said member out of engagement with said screws at the lower end of its movement, to effect additional sharpening of the lower end portion of said knife.

1'7. In a cloth cutting machine of the motor driven reciprocating knife type, a pair of grinders, means driven by a motor for rotating said grinders, means driven by said motor for moving said grinders down and up said knife, and a manually operable stop member for preventing the action of said last mentioned means when the grinders are in engagement with the lower end portion of the knife.

18. In a cloth cutting machine of the motor driven reciprocating knife type, a pair of vertically disposed parallel rotatable screws, means for simultaneously rotating said screws, a vertically movable member, grinders carried thereby, a transversely movable member on said first mentioned member and having a part for engaging said screws alternately to effect up and down movement of said first mentioned member and said grinders, a vertical guide bar for holding said transversely movable member against movement in respect to said vertically movable member, except at the upper and lower ends of the vertical movement of said first mentioned member, and means operable at will to hold said transversely movable member out of engagement with said screws at the lower end of its movement.

19. A cloth cutting machine having a knife, a motor for reciprocating said knife, rotatable grinders for said knife, and manually operable driving connections between said grinders and said motor for rotating said grinders and moving them down and then up along said knife, said driving connections including a variable speed means for changing the time cycle of said down and up movement.

20. A cloth cutting machine having a knife, a pair of rotatable grinders movable down and up along said knife, a motor for reciprocating said knife, and driving connections between said motor and said grinders for moving said grinders down and up along said knife, said driving connection including a variable speed drive.

21. In a cloth cutting machine of the motor driven reciprocating knife type, knife sharpening elements, a pair of motor driven vertically disposed parallel screws, a member movable transversely into engagement with said screws alternately, whereby when engaging one screw said member is moved downwardly, and while engaging the other screws is moved upwardly, said knife sharpening elements being operatively connected to said member and moved up and down by said member for sharpening the knife, and means for varying the speed of rotation of said screws in respect to the speed of reciprocation of said knife.

MARTIN ZAWISTOWSKI.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 661,693 Hazelhurst Nov. 13, 1900 2,300,534 Clark et al Nov. 3, 1942 2,300,535 Clark Nov. 3, 1942 2,444,909 Bangser July 13, 1948