US3653345A - Sewing machine for making welted pockets - Google Patents

Abstract

Sewing machine for making welted pockets comprising an arm carrying a driving shaft, a lock mechanism, a work plate slidable along the longitudinal axis of the machine beneath said arm, a work clamp movable with the work plate to secure thereon a piece of fabric to be sewn, a pair of lateral pressers movable with the work plate and a center blade, said pressers being provided for positioning a patch of fabric over said fabric and thereafter making a suitable folding of said patch, a pair of needles operatively connected to said driving shaft to form two parallel longitudinal stitchings on the fabrics after said folding, the fabrics moving together with the work plate, a cutter movable together with the needles to make a slit on the fabric parallel to the stitchings, vertically movable patch turners and tab slit cutters positioned below the work plate at the end of the displacement of said work plate and pneumatic means to control and actuate the operation of the machine lock mechanism, the movement of the work plate supporting the fabric, the oscillation of the patch turners and the tab slit cutters, the lateral movement of the presser members and the work clamp, pre-set control members being provided in the circuit of said driving means to determine the succession of their operation during the automatic cycle.

Description

United States Patent 1151 3,653,345 Bianchi [4 1 Apr. 4, 1972 [541 SEWING MACHINE FOR MAKING Primary Examiner-James R. Boler WELTED POCKETS 72 Inventor: Nereo Bianchi, Pavia, Italy [73] Assignee: Necchi, Societa per Azioni, Pavia, Italy [22] Filed: July 27, 1970 [21] Appl. No.: 58,577

[] Foreign Application Priority Data July 30, 1969 Italy ..32417 A/69 [52] U.S.Cl ..ll2/65,1l2/l21.1l [51 Int. Cl. ..D05b 3/10 [58] FieldofSearch ..ll2/65, 70, 74, 121.12, 121.15, ll2/l2l.l l, 264

[56] References Cited UNITED STATES PATENTS 2,573,359 10/1951 Rich ..ll2/65 OTHER PUBLICATIONS Reece Series P W, Pocket Welting Machine, 2nd Edition by the Reece Corp., pp. Cover & 21, Feb. 1965.

Attorney-Stevens, Davis, Miller & Mosher [57] ABSTRACT Sewing machine for making welted pockets comprising an arm carrying a driving shaft, a lock mechanism, a work plate slidable along the longitudinal axis of the machine beneath said arm, a work clamp movable with the work plate to secure thereon a piece of fabric to be sewn, a pair of lateral pressers movable with the work plate and a center blade, said pressers being provided for positioning a patch of fabric over said fabric and thereafter making a suitable folding of said patch, a pair of needles operatively connected to said driving shaft to form two parallel longitudinal stitchings on the fabrics after said folding, the fabrics moving together with the work plate, a cutter movable together with the needles to make a slit on the fabric parallel to the stitchings, vertically movable patch turners and tab slit cutters positioned below the work plate at the end of the displacement of said work plate and pneumatic means to control and actuate the operation of the machine lock mechanism, the movement of the work plate supporting the fabric, the oscillation of the patch tumers and the tab slit cutters, the lateral movement of the presser members and the work clamp, pre-set control members being provided in the circuit of said driving means to determine the succession of their operation during the automatic cycle.

5 Claims, '5 Drawing Figures I P l 18 67 as 5 Cb 52 53 43 35 0 2 120 i 42 361 i 1.] c1 e 1112 5 27 03 1 PATENTEBAFR 419m 3,658,345

SHEEI 2 [1F 3 1 SEWING MACHINE FOR MAKING WELTED POCKETS The present invention relates to a sewing machine for making welted pockets comprising a work plate slidable along the longitudinal axis of the machine, a work clamp movable with the work plate to secure on it a piece of the basic fabric, a pair of spaced pressers movable longitudinally with the work plate and laterally at a given time, and a fixed center blade, said pressers being provided for positioning a patch of fabric over said basic fabric and after a suitable folding a pair of needles moving together with the work plate to form on the fabrics two parallel longitudinal stitchings, a cutter movable with the needles to cut a slit in the fabrics parallel to the stitchings, patch turners and tab slit cutters to work on the fabrics at the completion of the stitchings; and driving, adjusting and controlling means for the execution of the foregoing phases of the operating cycle.

An object of the invention is to improve driving means generally, and particularly some of the structural parts forming said systems. It is well known that among driving means used in the sewing machines of the type mentioned, the pneumatic system offers evident advantages, in comparison with the electric or hydraulic fluid systems, as to the functional simplicity, the cost of the members, the removal of the danger of soiling the fabric to be sewn owing to oil leakage, and so on. On the other hand the pnuematic system is not suitable to obtain certain specific performances required by said sewing machines such as the movement of a work supporting member which must move with absolute evenness and with a special motion.

The technical problem to be solved to attain the mentioned purpose is to provide the machine with a pneumatic driving system in order to obtain all the operations of the automatic cycle, with the exception of the stitching operation which is accomplished by the sewing machine electric motor, by modifying that part of the drive system relating to the movement of the work clamp carrying the fabric so as to have an even movement, speed adjustment and the jogging f the work clamp in the various phases of the operating cycle.

The present solution to the technical problem set forth is characterized in that pneumatic driving means are provided for controlling the machine lock mechanism, the movement of the work plate supporting the fabric, the operation of the patch turners, tab slit cutters, the presser members and the work clamp, pre-set control members being provided in the circuit of said driving means to determine the succession of their operation during the automatic cycle. Additionally, the means provided for moving said work plate are formed by a pneumatic driving cylinder and a hydraulic fluid control cylinder, the rods of both cylinders being connected with said work plate and outer hydraulic line of said control cylinder has two parallel branches with a pilot valve on one and a reducing check valve on the other, said pilot valve and said reducing check being in series with a rotary-valve which is provided to obtain jogging of said work plate and with an additional reducing check valve.

A further feature of the invention is that said rotary valve is mounted on a machine driving shaft and, when the machine stops, the valve always has its port open to the control cylinder in order to stop the jogging of the work plate when sewing operations are not to be made.

Another feature of the invention is a single cylinder secured to the machine arm to effect the displacements of side pressers, center blade and the device for drawing sewing threads from the thread holders. The rod of said cylinder driving side pressers and center blade is connected by a lever system with the mounting of said center blade which is vertically slidable along suitable guides. A double cam is secured to the machine arm and is coupled with two cam followers connected with two levers adapted to rotate around fixed pins owing to the action of same cam followers. Rotation of said levers moves the side pressers to cause them to make lateral displacements relative to the longitudinal axis of the sewing machine.

Further features and advantages of the invention will be apparent from the following specification and the attached illustrative drawings in which:

FIG. 1 shows a schematic, partial sectional view of the assembly of the machine of the invention;

FIG. 2 is a partial view along line 2-2 of FIG. 1 to show a detail of the invention in one work position;

FIG. 3 is a partial view along line 3-3 of FIG. 1 to show a detail of the invention in one work position;

FIG. 4 shows another detail of the machine of FIG. 1 and FIG. 5 is a schematic view of the pneumatic control system connecting the various driving means of the machine of FIG. 1.

The operations to make a welted pocket or piped buttonhole will now be described. First, it is necessary to place a piece of basic fabric, simply called fabric hereinafter, on a work plate adapted to move in a straight line under the needle along the sewing machine's longitudinal axis, and to secure said fabric onto the work plate by means of work clamp adapted to follow the movement of the work plate. A piece of patch fabric is then placed onto said work clamp and between the two spaced side pressers and under a center blade located above and between said spaced side pressers and like them having its axis along the direction of the sewing machine longitudinal axis. The side pressers are prearranged to follow the work plate in its movement. The center blade is always in a fixed position. The center blade has an inverted T-shaped cross section and side pressers are blade-shaped. By first depressing the center blade and then causing the two side pressers to converge on the center blade the patch fabric is folded into the shape of an inverted T, with the side edges turned upward and brought near each other, and secured between side pressers and central blade.

The work plate is then actuated with the work clamp and side pressers moving along the sewing machine's longitudinal axis under a pair of needles to form two parallel longitudinal stitchings. A cutter, moving together with needles, makes a slit parallel to the stitchings and central relative to them. As will be seen hereinafter, this slit will be longitudinally inside the sewing.

The machine stops when the stitchings and the slit have been made. The work plate continues its movement until it stops in correspondence with patch turners and tab slit cutters which have been placed under the same work plate. The patch turners and tab slit cutters then move upwardly to make two cuts having the shape of a inverted V in both the fabric and the patch to join each of the two ends of the previously made slit to the corresponding pair of stitching ends. Thereafter said patch turners and tab slit cutters make a downward stroke to turn the tabs inside out by dragging them down through the slit.

Means are provided to cause jogging of the work plate during sewing and to slow down its movement at the beginning and at the end of the stitching operation in order to strengthen the stitches which are of the chain type.

The piped buttonhole sewing machine shown in FIG. 1 is provided with a bed 1, a standard 2 raising from said bed, an arm 3 extending parallel to said bed 1, and a head 4 placed at the front end of said arm 3. Bed 1 is hinged on a base 5 in such a way as to allow the sewing machine to be turned over for inspection of the machine members provided under the bed. Arm 3 carries interiorly a shaft 10 at whose front end a counterweight 11 is secured in a known way. Said shaft transmits motion, by means of a connecting rod 12, to needle bar 13 carrying a clamp 14 to which a pair of needles 15 is fixed. -At the other end of said shaft 10 two pulleys l6 and 17 are suitably mounted to receive the driving belt (not shown in the drawings) connected with the sewing machine electric motor.

Displacement of the belt from pulley 16, when in mesh with shaft 10, to pulley 17 which is idly mounted on said shaft, is obtained by a belt shifter (not shown in the drawings) connectedwith a well-known lock mechanism generally indicated at 18 and driven by a pneumatic cylinder Cb. A rod 20 is connected with said lock 18 and is adapted to slide in the upper part of arm 3. The front end 21 of rod acting on opposed axes 22 of two well-known thread devices 123 (FIGS. 2 and 3 neutralizes the same tension when the machine is locked. A toothed belt 25 driven by a toothed pulley 26 which is secured to shaft 10 transmits the motion of said shaft to a lower shaft (not shown in the drawings) provided in bed 1. The lower shaft by means of a pair of bevel gears, causes cross shaft 27 to rotate. Shaft 27, in turn, by means of two pairs of cylindrical toothed wheels, causes two opposed shafts 28 to rotate, one of them being shown in FIG. 1, on which two hooks are suitably mounted to grasp threads of needles 15 and to form the chain stitch.

On bed 1 of the sewing machine work plate 30 is positioned for slidable movement parallel to shaft 10. The movement of work plate 30 is caused by a double-acting pneumatic cylinder Cs and by a hydraulic fluid control cylinder C0 adapted to make uniform and adjustable the speed of work plate 30. A balance cylinder 120 is connected with control cylinder Co. Cylinders Cs and Co are secured by means of ring nuts 65 to a block 63 connected with bed 1 of the sewing machine. Rods 121 of said cylinders Cs and Co act on a mounting 122 which is fixed to work plate 30, to which mounting a simple-acting pneumatic cylinder Cl is hinged. A work clamp 32 driven by said cylinder Ct is secured to work plate 30.

The drive connection between work clamp presser 32 and cylinder Ct comprises a pair of levers 33 pivotally mounted on a pin 34 mounted on work plate 30 which pin is integral with a pair of forked levers 35. Each forked lever 35 is in sliding connection with block 36 mounted on rod 37 of cylinder Cr and on which block a pair of levers 39 are pivotally mounted at one end, the other end of said levers being pivotally mounted about pin 40. A mounting 126 is also pivotally mounted on pin 40 at an end, the other end resting on work plate 30 and controlling the pressure of work clamp 32 onto fabric. A pair of spaced blocks 41 are slidably mounted on pin 34. An arm 42 is secured at one end to each block and carries at the other, lower end a laterally movable side presser 43 positionable over work clamp 32. The two laterally moving side pressers 43 move in correspondence with the machine axis and therefore to close toward each other as a result of the action of tension spring 44 anchored to the upper ends of arms 42 of said side pressers 43 and to central block 45 integral with pin 34.

During the forward displacements of work clamp 30, prongs 46 (FIG. 4) of said blocks 41 slide into contact with a pair of levers 47 pivotally mounted on shafts 48 and 49, respectively. Each of the shafts 48 and 49 is parallel to shaft 10 and each has integral therewith an arm 50 carrying a cam follower 51 in mesh with cam 52 (FIGS. 1, 2 and 3). Said cam 52 is slidable along rod 53 of center blade 62 of the machine and is connected through a connecting rod 54 with arm 55 of a forked lever 56 pivotally mounted on pin 57 in arm 3. Fork of lever 56 is in mesh with a block 58 integral with rod 59 of a pneumatic simple-acting cylinder Cp mounted within arm 3. In FIG. 1 cylinder Cp is shown in its work position keeping cam 52 up, and said cam 52 in turn, keeps side pressers 43 opened against the action of spring 44. In this condition cam 52 urges collar 60 of rod 53 against the action of a spring (not shown in the drawings) which is coaxial with the rod and therefore keeps also center blade 62 in a raised position.

When the compressed air flow to cylinder Cp has stopped, the rod 59 is returned to its rest position by action of the spring inside the cylinder housing. Cam 52 leaves collar 60 of rod 53 whereby center blade 62 is lowered to its work position, and rotation of levers 47 subsequently brings lateral pressers 43 to a close position. Vice versa, going from rest position to work position, flow of compressed air into cylinder Cp cams levers 47 apart and hence the pressers 43 and thereafter center blade 62 is raised (FIGS. 1 and 3). During power stroke of cylinder Cp block 58 urges rod 67 mounted on block 57 and within arm 3 parallel to shaft 10 to project from the contour of head 4 against the action of spring 68. Rod 67 has a projection 69 upon which the sewing threads slide. The projecting of rod 67 causes therefore sewing threads to be drawn from their respective holders through thread tension devices opened by the machine lock mechanism. This is necessary to begin a new sewing operation without having needles unthreaded.

Block 45 integral with pin 34 on work plate 30 has a slot 70 in which a rod 71 is slidably mounted within arm 3. A cutter 72 is pivotally mounted on the needle clamp 14, between the two needles 15. This cutter 72 is kept in the position shown in FIG. 1, against adjustable striker 73 of clamp 14, by a coil spring 74. Adjustment made on striker 73 allows positioning of cutter 72 in front of needles 15 as required at the end of the sewing operation. A movable striker 75 pivoted about pin 76 on arm 3 is connected with said rod 71. At the beginning of the sewing operation said striker 75 is in the position shown in FIG. 1. A projection 77 of cutter 72 slides against striker 75 during downward movement of needles 15. Said cutter 72 rotates then around its pivot point so that when penetrating the fabric it is positioned behind needles. The combination nullifying sliding contact between projection 77 and striker 75 after making the first strip of the sewing operation is formed by the said block 45 in whose slot 70 rod 7] slides, spring 78 which is coaxial with rod 71 reacts against said block 45 and against spacer 79 which is also coaxial with rod 71, and urges said spacer against nut 80 placed at the threaded end 81 of same rod 71 together with lock nut 82.

Rod 71 is therefore kept in the position shown in FIG. 1, that is in the position controlled by contact of nut 83 against arm 3, as long as the leftward displacements of block 45 have released spring 78, thus allowing the action of a counteracting spring 84 to move nut 80 into contact with a standard wit 2 and cause striker 75 to rotate out of sliding contact with projection 77 of cutter 72. By means of a device mentioned hereinafter cutter cuts the fabric along a longitudinal line between the two parallel stitchings. It is evident that adjusting the positions of nuts 80 and 83, and of their respective lock nuts, makes it possible to adjust the stroke and position of striker 75.

At the end of the sewing operation, when the machine has been locked in the way shown hereinafter and after work plate 30 has finished its stroke, patch tumers and tab slit cutters 110 and patch tumers 112 are operated by patch turner pneumatic drive cylinder Cr. A block is connected with double-acting pneumatic cylinder Cr which is secured under bed 1, said block 100 acting on a pin 101 of lever 102 free to rotate about pin 103. One end of said lever 102 is connected with a connecting rod fixed to a vertical sliding member 104 carrying a pin 105 sliding in a groove 106 of a vertical plate 107 secured to the underside of bed 1. g

A mounting bar 109 is fixed, by means of screws 108, to sliding member 104. Said mounting bar 109 carries at its ends patch tumers 110 carrying in turn at their upper end slit cutters 111. Said mounting bar 109 carries, in its central part, patch turners 112, similar to those indicated at 110 but without cutters 1 l1, suitable to turn the patch previously sewn and cut. The distance between patch tumers and tab slit cutters 110 and patch tumers 112 is adjustable by displacing mounting arms 113 and 114 respectively.

During the raising of patch turners 112, cutters 111 out two tab slits in the form of a 90 inverted V. Each V-shaped slit joins the end of the slit made by cutter 72 with the respective ends of the parallel stitching thus making it possible for the folding operation to be executed during the downward stroke of patch tumers 110 and tab slit cutters 111 and patch turners 112.

The operating cycle now will be described with reference to FIG. 5. The main compressed air line has a filter F, a gauge M and an oiler L and an electrovalve Ws which opens upon the closing of the main switch in the machine electric feed line. The operator begins the automatic cycle by pressing down on the heel treadle P. By said operation valve V2 is opened to let compressed air flow through pilot valve Wd and valve S1 to operate cylinder Cb to disengage the lock mechanism thus permitting the sewing machine to operate. At the lock opening the rod of cylinder Cb by its downward displacement opens valve V1 allowing compressed air to flow through said valve V1 and to vary the pre-arrangement of pilot valves Wp and Wr. Through valve Wp and tee valve D4 compressed air reaches work plate drive cylinder Cs which causes jogging of the work plate 30 at a low speed.

The jogging of work plate 30 is obtained by means of a wellknown rotary valve T driving the work plate feed shaft, the rotation of which valve is caused by machine shaft and closes and opens by turns the conduit of the hydraulic fluid cylinder Co which controls the speed of Cylinder Cs. Low speed is obtained by the compressed air flowing through valve V7 and tee valve D7 when pilot valve W0 is closed. Cylinder C0 passes through said valve T and the reducing check valves R3 and R2 and does not pass directly through pilot valve W0.

When the machine is operating, work plate 30 moves slowly and after moving a short distance closes valve V7. As valve V7 closes, the action of compressed air on pilot valve W0 of the hydraulic fluid circuit is interrupted. Then the fluid can freely pass from valve T through valve W0 and the work plate 30 can be displaced quickly. After the machine starts up, treadle P can be returned to its rest position by reverse flow through pilot valve Wd. This however is not essential for the cycle execution.

When the work plate 30, just before the end of the sewing operation, opens valve V8, it slows up owing to closing of valve W0 caused by opening valve V8. Continuing its stroke, work plate 30 opens valve V9 allowing compressed air to pass; pilot valve Wd is driven through tee valve D1 into pilot valve Wd and consequently to lock drive cylinder Cb causing the piston to return to its initial position to engage the lock. The sewing machine comes to rest and rotary valve T driving the jogging of work plate 30, stops in an open position. Then work plate 30 opens valve V10 allowing compressed air to pass through tee valve D6 to cause the raising of center blade 62 and separation of side pressers 43 by means of the actuation of cylinder p. In the meanwhile, the closing of valve V8 by work plate 30 and the resulting opening of valve W0 produces a quicker movement of the work plate 30. The jogging had already ceased by the stopping of rotary valve T. Work plate 30 reaches its stroke end and in addition to having opened valves V9 and V10, it now opens valve V1 1.

Cylinder Cr driving patch turners and tab slit cutters 110 and patch turners 112 is actuated by means of pilot valve Wr and tee valve D8. Cylinder Cr opens, at the end of the stroke of its piston rod, valve V12 which actuates pilot valve Wr and compressed air from valve V11 passes through valve W r and then tee valves D9 and D10 placed in parallel. The first of said tee valves D9 feeds air for the back stroke of the piston of cylinder Cr. The second valve D10 feeds valve V13, temporarily closed by the rod of cylinder Cr. The piston of cylinder Cr reaches the end of its back stroke and reopens valve V13 through which compressed air reaches cylinder Ct which causes the raising of work clamp 32 (FIG. 1). Opening valve V13 also allows air to pass to tee valve D3 actuating pilot valve Wp. Through said valve Wp compressed air reaches valve V5, which is closed, and also tee valve D2 with which valves V4 and V3 are connected in parallel, said valves too being closed.

In order to return the work plate to its position at the beginning of the sewing cycle it is necessary to move pedal P forward to open valves V3, V4 and V5 at the same time. The opening of valve V3 supplies air to cylinder Cp when work plate 30 in its back stroke closes valve V10. The opening of valve V4 supplies air to cylinder Ct also when work plate 30 in its back stroke closes valve V1 1. The opening of valve V5 supplies air through tee valve D5 for the back stroke of cylinder Cs driving work plate 30. The back stroke of work plate 30 takes place quickly and is not effected by the opening and closing of valves V7 and V8. When work plate 30 has come back to its starting position it is possible to position on the sewing machine the fabric on which piped buttonhole has to be performed.

By pressing treadle P to an intermediate forward position, in which valves V4 and V5 are closed and V3 only is open, center blade 62 and lateral pressers 43 are held away from work plate 30 (cylinder Cp being supplied with air) and work clamp 32 is kept lowered (cylinder Ct not being supplied with air). In these conditions it is possible for the piped buttonhole performing.

Returning treadle P to its rest position closes valve V3. Therefore cylinder Cp is not supplied with air thus lowering center blade 62 and lateral pressers 43. The machine is ready to begin a new operating cycle. By switching of the lever of cycle drive valve A to the emergency position shown by dotted lines the following effects are obtained:

valves V1, V2, V7, V8, VII and V12 are not supplied with air;

plunger operated valves Si causing backward movementof work plate 30, causing forward movement of same work plate 30, and Ra causing upward movement of patch turners and 112 are supplied with air;

tee valves D1, D2 and D3 are supplied with air. The first of them ensures switching of pilot valve Wd to the machine lock driving position and locks the machine. From tee valve D2 compressed air reaches the inlets of valves V3 and V4, so that the eventual following forward movement of treadle P will operate the center blade and lateral pressers via cylinder Cp and the work clamp will be raised by cylinder Ct. Non-supply of air to valve V5 does not allow treadle P, by its forward movement, to provide back stroke supplying of air to work plate driving cylinder Cs through tee valve D5. On the other hand positive feeding of cylinder Cs has been interrupted by the switching of valve Wp made through tee valve D3 and therefore the work plate stops in the position occupied at the moment of switching of drive valve A to emergency.

supplying air to cylinder Cr to move the patch turners.

After the safety shutdown it is possible to make the following maneuvers;

to push forward on treadle P to drive, in the described way, the center blade 62 and lateral pressers 43 and cause the rising of work clamp 32;

to act onto pushbutton Si to cause backward movement of work plate 30, by supplying air to cylinder Cs through tee valve D5;

to act on pushbutton S0 to cause forward movement of work plate by supplying air to cylinder Cs through tee valve D4;

to act onto valve Ri to cause downward movement of patch turners 110 and 112: the air is transmitted through quick exhaust valve S2 operating through tee valve D9 for the back stroke of cylinder Cr and through tee valve D11 to ensure that pilot valve Wr is switched toward same tee valve D9;

to act onto pushbutton Ra to cause upward movement of patch turners 110 and 112: the air is transmitted through valve V6 and tee valve D8 to cylinder Cr and that is when cylinders Cs and therefore work plate 30, are in the position of maximum displacement at which time valve V6 is open.

Positioning of lever of valve Ri in the position to cause the downward movement of patch turners 110 and 112 does not vary the normal cycle of the machine, but excludes only the phases described relative to the switching of valves V9, V10 and V11 operated by work plate 30 when it reaches the maximum displaced position, because it keeps valve Wr always oriented toward tee valves D9 and D10.

I claim:

1. Sewing machine for making welted pockets comprising an arm carrying a driving shaft, a lock mechanism, a work plate slidable along the longitudinal axis of the machine beneath said arm, a work clamp movable with the work plate to secure thereon a piece of fabric to be sewn, a pair of lateral pressers movable with the work plate and a center blade, said pressers being provided for positioning a patch of fabric over said fabric and thereafter making a suitable folding of said patch, a pair of needles operatively connected to said driving shaft to form two parallel longitudinal stitchings on the fabrics after said folding, the fabrics moving together with the work plate, a cutter movable together with the needles to make a slit on the fabric parallel to the stitchings, vertically movable patch turners and tab slit cutters positioned below the work plate at the end of the displacement of said work plate and pneumatic means to control and actuate the operation of the machine lock mechanism, the movement of the work plate supporting the fabric, the oscillation of the patch turners and the tab slit cutters, the lateral movement of the presser members and the work clamp, pre-set control members being provided in the circuit of said driving means to determine the succession of their operation during the automatic cycle, wherein the means provided for work plate feeding are formed by a pneumatic driving cylinder and a hydraulic fluid control cylinder, the rods of both cylinders being connected to said work plate, the fluid line of said control cylinder having two parallel branches, a pilot valve on one branch and a reducing check valve on the second branch, a rotary valve for causing jogging of said work plate, and an additional reducing check valve, said pilot valve and said reducing check valve being in series with said rotary .valve and with said additional reducing check valve.

2. Sewing machine according to claim 1 wherein said rotary valve is mounted on said machine driving shaft and, when the machine stops, has always its port closed at the control cylinder in order to stop the jogging of the work plate whensewing operations are not to be made.

3. Sewing machine according to claim 7, including a device for drawing sewing threads from the thread holders, wherein the driving means to cause the displacement of said lateral pressers, center blade and said device for drawing sewing threads from the thread holders comprises a single cylinder secured to the machine arm and a cam actuated lever assembly connecting said cylinder to said presser, center blade, and the device for drawing threads from said holders.

4. Sewing machine according to claim 3 including a mounting means for said center blade wherein the piston rod of said cylinder is connected by a lever system with said mounting means, guides on which said mounting means are vertically slidable, further including two parallel levers rotatable along the underside of said arm, two cam followers connected to said levers, and a double cam secured interiorly of said arm and coupled with said two cam followers, fixed pins about which said levers are adapted to rotate owing to the action of said cam followers, each of said levers being in contact with one of said lateral pressers, said pressers being slidably mounted to make cross displacements relative to the sewing machine longitudinal axis, tensioning means urging said pressers towards each other, said pressers being held apart by said levers.

5. Sewing machine according to claim 4, wherein said cam is a groove type cam and has upper raking portions radiusing with lower vertical portions, said upper raking portions being arranged for closing the lateral pressers after the center blade has lowered during contact of said cam followers with said vertical portions and opening of said side pressers before the raising of said center blade in the following phase of presser opening.

Claims (5)

1. Sewing machine for making welted pockets comprising an arm carrying a driving shaft, a lock mechanism, a work plate slidable along the longitudinal axis of the machine beneath said arm, a work clamp movable with the work plate to secure thereon a piece of fabric to be sewn, a pair of lateral pressers movable with the work plate and a center blade, said pressers being provided for positioning a patch of fabric over said fabric and thereafter making a suitable folding of said patch, a pair of needles operatively connected to said driving shaft to form two parallel longitudinal stitchings on the fabrics after said folding, the fabrics moving together with the work plate, a cutter movable together with the needles to make a slit on the fabric parallel to the stitchings, vertically movable patch turners and tab slit cutters positioned below the work plate at the end of the displacement of said work plate and pneumatic means to control and actuate the operation of the machine lock mechanism, the movement of the work plate supporting the fabric, the oscillation of the patch turners and the tab slit cutters, the lateral movement of the presser members and the work clamp, pre-set control members being provided in the circuit of said driving means to determine the succession of their operation during the automatic cycle, wherein the means provided for work plate feeding are formed by a pneumatic driving cylinder and a hydraulic fluid control cylinder, the rods of both cylinders being connected to said work plate, the fluid line of said control cylinder having two parallel branches, a pilot valve on one branch and a reducing check valve on the second branch, a rotary valve for causing jogging of said work plate, and an additional reducing check valve, said pilot valve and said reducing check valve being in series with said rotary valve and with said additional reducing check valve.

2. Sewing machine according to claim 1 wherein said rotary valve is mounted on said machine driving shaft and, when the machine stops, has always its port closed at the control cylinder in order to stop the jogging of the work plate when sewing operations are not to be made.

3. Sewing machine according to claim 7, including a device for drawing sewing threads from the thread holders, wherein the driving means to cause the displacement of said lateral pressers, center blade and said device for drawing sewing threads from the thread holders comprises a single cylinder secured to the machine arm and a cam actuated lever assembly connecting said cylinder to said presser, center blade, and the device for drawing threads from said holders.

4. Sewing machine according to claim 3 including a mounting means for said center blade wherein the piston rod of said cylinder is connected by a lever system with said mounting means, guides on which said mounting means are vertically slidable, further including two parallel levers rotatable along the underside of said arm, two cam followers connected to said levers, and a double cam secured interiorly of said arm and coupled with said two cam followers, fixed pins about which said levers are adapted to rotate owing to the action of said cam followers, each of said levers being in contact with one of said lateral pressers, said pressers being slidably mounted to make cross displacements relative to the sewing machine longitudinal axis, tensioning means urging said pressers towards each other, said pressers being held apart by said levers.

5. Sewing machine according to claim 4, wherein said cam is a groove type cam and has upper raking portions radiusing with lower vertical portions, said upper raking portions being arranged for closing the lateral pressers after the center blade has lowered during contact of said cam followers with said vertical portions and opening of said side pressers before the raising of said center blade in the following phase of presser opening.

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