US3726240A

US3726240A - Automatic sewing machine

Info

Publication number: US3726240A
Application number: US00114822A
Authority: US
Inventors: W Emich
Original assignee: SWIRL Inc
Current assignee: SWIRL Inc
Priority date: 1971-02-12
Filing date: 1971-02-12
Publication date: 1973-04-10
Anticipated expiration: 1990-04-10

Abstract

A sewing machine for producing sash belts is provided with a timer-operated control means which, following manual initiation by an operator, produces an initially slow operation of the machine to allow proper operation of an automatic thread cutter; effects formation of a gap for turning the sash belt at a midpoint between first and second aligned seams; and finally stacks the completed product by means of an air blast.

Description

e W: v 1 iJite States 1 aeiit 1 1 1 1 9 Emich 5] Apr. 10, 1973 [54] AUTOMATIC SEWING MACIME 1,191,233 7/1916 Richards ..112/221 3,204,591 9/1965 Pickett [75] Inventor. William Emlch, Greenville, S.C. 2,521,360 9/1950 Gemein" [73] Assignee: Swirl, Inc, Easley, S.C. 3,025,807 3/1962 Gebert ..112/221 X [22] Filed: 1971 Primary Examiner-James R. Boler Appl- 114,322 AttorneySmith, Harding, Earley & Follmer 52 us. c1. ..112/121.11,112/121.29, 112/221, [571 ABSTRACT 1 12/255 1 12/214 A sewing machine for producing sash belts is provided [51] Int. Cl. ..DOSb 19/00 with a timer operated comm] means which f ll i [58] Fleld of Search ..1 12/221, 121.1 1, manual initiation by an operator, produces an initially 1 12/214 21 slow operation of the machine to allow proper opera- 12129 158 R tion of an automatic thread cutter; effects formation of a gap for turning the sash belt at a mid-point [56] References Cited between first and second aligned seams; and finally UNITED STATES PATENTS stacks the completed product by means of an air blast.

3,559,601 2/1971 Tullman ..1 12/158 R 6 Claims, 10 Drawing Figures PATENTED W 3,726,240

SHEET 1 BF 5 HQvENTOR WILLIAM EMICH 5:111 HWQJwJ L- ATTORNEYS PATEIHED 3,726,240

sum 3 or 5 TIMER 286 I TIMER 292 I TIMER 288 TIMER 294 TIMER 290 m TIMER 386 I I I I II I I g SLOW FAST SKIP FAST AIR BLAST F l G 4.

F I G. 6.

INVENTOR WILLIAM EMICH Fl 6. 7. SM Hm; w wwm ATTORNEYS AUTOMATIC SEWING MACHINE BACKGROUND OF THE INVENTION This invention relates to automatic sewing machines and particularly to a machine for producing sash belts for dresses.

In the past, sash belts have been produced on conventional sewing machines. Typically, a sash belt is made by folding a piece of fabric in half lengthwise and sewing the edges together along a seam. In order to produce the finished product, it is necessary to turn the belt inside out. For this reason, a gap is left in the seam which the tube of a turning machine can be made to enter. This gap is generally located about midway between the ends of the belt..

On a conventional sewing machine, the formation of a gap involves a number of complex operations all of which take place, from the standpoint of time, in the middle of the operation on a particular sash belt, and all of which require the attention of the operator.

Formation of the gap requires pulling the fabric through the sewing machine for a short distance while the needle is not operating. The pull of the fabric to produce the gap is liable to produce thread breakage, and when the pull is effected manually, uniformity of the product suffers.

At the end of the operation, the product must be removed from the machine, and this requires the operators attention where the conventional machine is used.

Another difficulty in the production of sash belts by the use of conventional machines is the cutting of excess thread, which also requires the attention of an operator both at the beginning and at the end of the sewing operation.

SUMMARY OF THE INVENTION In accordance with this invention, there is provided a control system which, following a manual initiation by an operator, causes the sewing machine to sew the first seam of the sash belt, thereafter produce a skip, and thereafter sew a second seam. In the production of the skip, the control system effects a uniform pull on the fabric and all operations incident thereto including the release of the presser foot, the positioning of the sewing machine needle and the looper to allow the movement of fabric and thread involved in the production of the gap, the re-engagement of the presser foot and the initiation of continued sewing.

The control system involves a series of electromechanical timers which operate in a predetermined sequence to control all machine operations following manual initiation.

The control system produces an initial slow operation of the sewing machine to allow time for operation of an automatic photocell-controlled thread cutter. The control system also controls a valve which produces a blast of air when the product clears the sewing machine mechanism to stack the product on a rack.

The control system is adjustable to accommodate different lengths of belts and to produce a gap of any desired length and at any desired location along the length of the belt.

The principal object of this invention is to provide a sash belt sewing machine which requires only a manual initiation and thereafter automatically performs all of the steps. incident to the sewing of a sash belt with the exception of closing of the ends and turning, thereby freeing the operator to perform other duties, for example, the operation of other similar sash belt machines. In this connection, it should be noted that some manually produced sash belts are provided with a continuous seam which curves to close the ends of the belt. While this avoids the subsequent step of closing the ends, the production of sash belts in that manner requires a great deal more operator time than is needed to produce a finished sash belt using the apparatus in accordance with this invention.

Other objects include the attainment of higher productivity, the production of uniform products, and the achievement of high reliability and flexibility in an automatic sewing machine.

Still further objects will be apparent from the following description when read in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevation of the sewing machine in accordancewith the invention;

FIG. 2 is a perspective view of the product of the sewing machine;

FIG. 3 is an exaggerated fragmentary elevation of the product showing how the stitches are separated to form a gap for turning;

FIG. 4 is a diagram illustrating the sequence of operation of the various electro-mechanical timers in the control system;

FIG. 5 is an elevation of the sewing machine as viewed from the left-hand side of FIG. 1;

FIG. 6 is an elevation of the sewing machine motor and various other parts located underneath a supporting table;

FIG. 7 is a sectional view showing the clutch-operating lever, one of the air cylinders which operates it, and associated switching means;

FIG. 8 is an elevation of the sewing machine as viewed from the right-hand side of FIG. 1;

FIG. 9 is a schematic diagram of the sewing machine control system; and

FIG. 10 is a schematic diagram of the control system for operating the automatic thread cutter.

DESCRIPTION OF THE PREFERRED EMBODIMENT The invention is built around a conventional sewing machine of the kind having a looping mechanism for producing a two-thread chain lockstitch. As shown in FIG. 1, the frame of the machine comprises a base 2, having a work supporting surface 4. From one end of the work supporting surface, there rises a standard 6, and an overhanging arm 10 (FIGS. 5 an 8) extends over the work supporting surface and terminates in a needle head 8.

Needle bar 12 extends vertically through the needle head and is arranged therein to be reciprocated by the conventional drive mechanism (not shown). A needle 14 is clamped at the lower end of needle bar 12.

A conventional looper and feed dogs are located at 16 underneath work supporting surface 4. A presser foot 18 is arranged above surface 4 at the lower end of presser bar 20. The presser foot cooperates with the feed dogs in the conventional manner to advance the work. Conventional lifting means (indicated at 21 in FIG. are provided for raising the presser foot away from the supporting surface 4. The lifting means, as will be explained in more detail subsequently, is operated by a solenoid 374 through connecting rod 23. Operation of the lifting means simultaneously effects a release of certain thread tensions which will be described.

At the top of the needle bar, there is mounted a thread guide 22. Thread from the supply passes through take-up 24 and then through guide 22 to the needle.

A V-folder 26 is arranged in the path of fabric approaching the location of the needle. The V-folder comprises a tapered metal cone having a pair of

layers

27 and 29, spaced from each other to provide an opening 31 for receiving fabric. As fabric is fed between these layers, it emerges from tip 33 in a folded condition and lined up with the needle in such a way that aseam will be produced at the desired position.

FIG. 8 shows thread 28 being guided from a thread supply (not shown) to the needle, and a looper thread 30 also guided from a supply to the looping mechanism underneath surface 4. Thread 28 passes through tension 32 and thread 30 similarly passes through tension 34. Both tensions are arranged to be released when the presser foot is raised by lifting means 21.

The main sewing machine drive shaft is indicated at 36, and it is driven through drive belt 40 which drives wheel 38 mounted on shaft 36. The belt and wheel are preferably of the type having meshing teeth to provide a positive transmission of power.

So far, the mechanism described is conventional, and for details reference may be made to U.S. Pat. No. 2,688,293 issued Sept. 7, 1954 to R. A. Hayes et al., and to U.S. Pat. No. 2,598,426 issued May 27, 1952 to A. C. Peterson et al.

As shown in FIGS. 1 and 8, a cutting knife 42 is mounted in a holder 44 located immediately behind the presser foot in the direction of fabric movement. The holder for the knife is pivoted at 46 in a bracket 52. Piston 48 of air cylinder 50 is connected to the opposite end of the knife holder. The knife is so arranged that its cutting edge is parallel to the supporting surface 4 when moved into contact therewith by operation of the piston.

A photocell 54 is mounted in bracket 52 next to the knife. The photocell is part of a control system for operating the knife. It faces downwardly, and normally receives light reflected by surface 4 from light source 55, also mounted in bracket 52. The purpose of the photocell is to detect the presence of an edge of the fabric, and to cut excess thread at the edge. The operation of the control system for operating the knife will be described subsequently. The photocell and light source are positioned so that the change from light to dark or from dark to light strikes the photocell when the fabric is still approaching the knife location. The exact arrangement of the light source and photocell depends on the fabric speed and the response time of the knife control system.

Referring to FIGS. 1 and 5, the cylindrical surface of an idler roller 56 extends upwardly a short distance through an opening in surface 4. The idler roller is engaged by a driven roller 58 which is rotatably mounted in a bracket 60 fastened to the lower end of bar 62. Bar 62 is mounted for vertical sliding movement in vertical holes in blocks 64 and 66, both of which are supported by bracket 67. Bracket 67 is fastened to the outside of the needle head 8.

At the upper end of bar 62 there is provided an extension 68 which threads into the upper end of bar 62 to allow for adjustment of the overall length. An air cylinder 70 is mounted at the top of bracket 72 and its piston 74 engages the knurled upper end 75 of extension 68. A coil spring 76 is held in compression between block 66 and ring 78 which is secured to bar 62 at a location above block 64. This spring imparts a light downward pressure urging the

rollers

56 and 58 together. In normal operation, air cylinder 70 is not operated, and roller 58 is urged downwardly by spring 76 and its own weight and the weight of parts which move with it. Additional pressure between the rollers is imparted when air cylinder 70 is operated. The pressure during normal operation is such as to allow a certain amount of slippage of roller 58 with respect to the fabric in order to insure a small amount of tension on the length of fabric between the feed dogs and the roller, but the pressure must not be so great as to cause tearing or buckling of the fabric as a result of differences in the rates of feed through the rollers and through the feed dogs.

Roller 58 is mounted on a shaft 80 which is rotated by shaft 82 through universal coupling 84, shaft 86 and universal coupling 88. Shaft 82 is one of the output shafts of a conventional gearbox 90 which receives its input through shaft 92. The other output of gearbox 90 is transmitted through shaft 94 to pulley 96 which drives pulley 98 through belt 100. Shaft 94 is supported in bearing 102, which is supported from table 104 by standard 106.

Referring to FIGS. 1 and 5, shaft 108 is driven by pulley 98. On shaft 108 there is mounted a conveyor roller 110 around which rolls a continuous conveyor belt 112. An idler roller 114 is shown in FIG. 5 at the far end of the conveyor. Both rollers are mounted between bearings supported in

brackets

116 and 118.

The conveyor assembly is located in the path of travel of fabric passing through the roller

assembly comprising rollers

56 and 58. A tube 120 having an open end 122 receives compressed air through a channel 124 underneath the edge of work supporting surface 4. After a piece of fabric clears the puller and begins to move down the conveyor, a blast of air is delivered through tube 120. This blows the work onto a rack. The manner in which the control system effects the operation of air tube 120 will be described subsequently.

FIG. 8 illustrates the mechanism for producing a slack in the two

threads

28 and 30.

Air cylinders

126 and 128 are mounted vertically on a suitable bracket 130. Both cylinders are of the type in which the piston is retracted when air is supplied to the cylinder. At the lower end of piston 132 of cylinder 126 there is fastened a bracket 134 which includes a guide 136 through which thread 28 passes. Bracket 134 is also provided with a vertical opening through which extends a vertical guide rod 138. A bracket 140 is fastened to the lower end of piston 141 of cylinder 128. Bracket 140 is guided in its travel by rod 138 and by plunger 132, since both extend through openings in bracket 140. A downwardly extending rod 142 terminates in a hook 144 which is so arranged with respect to looper thread 30 that retraction of piston 141 will result in the production of a slack in thread 30.

Cylinders

126 and 128 are simultaneously operated by the control system immediately following the release of

tensions

32 and 34. They produce slack in both threads sufficient to accommodate the pull which takes place in the step producing the gap in the sash belt. Were it not for the production of this slack, a pucker would be produced in the sash belt.

Rotational power for the main sewing machine drive shaft, the conveyor, and puller roller 58 is derived in those parts of the operation involving actual sewing, from the main sewing machine motor 146. Motor 146 is provided with aclutch 148 operated by a lever 150. The motor shaft 152 is connected through clutch 148 to shaft 154. As is the usual case in sewing machines, a partial movement of the clutch lever between its extremes of movement results in a slipping operation of the clutch producing a rotation of shaft 154 which is relatively slow compared to its normal speed with the clutch fully engaged. Shaft 154 drives a pulley 156 which, in turn, drives pulley 158 through belt 160. Shaft 162 is driven by pulley 158. Shaft 162 is the input shaft of a conventional needle positioner 164. The needle positioner motor is indicated at 166, .and its output shaft is shown at 168. Shaft 168 drives sewing machine shaft 36 through pulley 170, belt 40 and pulley 38. The needle positioner comprises a differential gearbox in which the position of the shaft of motor 166 is added to the position of shaft 162 to determine the position of output shaft 168. Switching is provided to cut off motor 166 whenever shaft 168 is so positioned that it corresponds to a raised condition of the sewing machine needle. Thus, whenever the sewing machine motor is stopped or drive shaft 154 is stopped, motor 166 can be made to continue in operation until the sewing machine needle is in a raised condition allowing fabric to be pulled underneath the tip of the needle and along the work support surface.

Also mounted on shaft 36 is a pulley 172 which drives a belt 174 connecting it to a pulley 176. Pulley 176 is one of the two relatively movable elements of a conventional clutch 178 which allows shaft 92 to be driven by pulley 176 and which also allows shaft 92 to be driven by pulley 180 with pulley 176 in a stationary condition. Pulley 180 is driven by belt 182 which connectspulley 180 with pulley 184 on the output shaft 186 of an air-actuated clutch 188. A suitable clutch is described in US Pat. No. 3,104,000 issued Sept. 17, 1963 to M. E. Erickson. The input shaft 190 is driven by auxiliary motor 192 through a right-angle gearbox 194.

FIGS. 6 and 7 illustrate the operating mechanism for clutch lever 150. Lever 150 is shown in FIG. 6 in its partially operated condition.

Frame member 196 extends horizontally underneath table 104. A bracket 198 mounted on frame member 196 supports an air cylinder 200. The downwardly extending piston 202 of the air cylinder engages the upwardly facing surface of lever 150 pushing the lever downwardly. A spring (not shown) within the housing of clutch 148 urges the lever upwardly.

Air cylinder 210 is mounted on frame members 196. Its piston 212 as shown in FIG. 7 extends upwardly through a hole 214 in lever 150. A nut 216 threaded onto the piston is adapted to engage the upwardly facing surface of the lever, causing the lever to be pulled downwardly when the air cylinder is operated. A hinged projecting member 218 is fastened to piston 212 just above nut 216. It is arranged to engage and operate arm 220 of microswitch 222 whenever piston 212 moves upwardly. The hinge 223 allows piston 212 to move downwardly without actuating microswitch 222. The microswitch is actuated only momentarily. This air cylinder mechanism is so arranged as to be capable of pulling the lever farther downwardly from the position to which it is pushed by air cylinder 200.

Air cylinder 204 is similarly mounted so that it can act as an alternate to cylinder 210. Its piston 206 extends upwardly through a hole in lever 150. Nut 208 is threaded onto piston 206 and adapted to engage the upwardly facing surface of the lever so that when air cylinder 204 is operated, the lever is pulled downwardly. A projection 209 is fastened above nut 208 and adapted to engage the operating arm of microswitch 394. This projection is similarly hinged so that microswitch 394 is momentarily actuated only on the upstroke of piston 206.

Returning to FIG. 6, there is shown a solenoid 224 mounted underneath table 104 and having an armature 226. A wire 228 fastened to the armature extends downwardly through a hole in lever and terminates in a bead 230 adapted to engage the underside of lever 150 so that when the solenoid is operated the lever is forced upwardly into the position in which the clutch is fully disengaged. The solenoid is provided to insure a rapid disengagement of the clutch which would otherwise be impeded by the slow return of the air cylinders to the non-operated position.

FIG. 10 shows the mechanism for actuating knife 42 to cut off excess thread from the ends of the sash belt. Photocell 54, which is arranged to detect the presence of an end of the sash belt, is connected electrically to conventional relay circuitry 232 which effects closure of contacts 234 for a short period of time each time a transition from light to dark or from dark to light is detected by the photocell. The transition corresponds to the presence of the leading edge of the fabric as it is introduced into the machine, or to the presence of the edge passing underneath the photocell as sewing of a belt is being completed. Contacts 234 connect power terminal 236 momentarily through line 238 to a solenoid 240 which operates a spool valve 242 receiving air under pressure through line 244 and delivering air to line 246 when the solenoid is energized. Valve 248 receives air through line 246 and is normally open allowing air to flow through its outlet line 250 into air cylinder 50 which operates the knife. An additional flow path for air in line 246 is provided by line 252 which delivers air through variable restriction 254 and line 256 to air cylinder 258. Piston 260 of air cylinder 258 is mechanically connected through connection 262 to the spool of valve 248, and arranged so that valve 248 tends to close as air enters cylinder 258. A spring 264 urges piston 260 in a direction tending to open valve 248. The variable restriction 254 is by-passed by a line 266 provided with a check valve 268.

As solenoid 240 operates, air immediately passes through

lines

244, 246 and 250 causing air cylinder 50 to impart a downward movement to the knife. As the flow of air through valve 242 continues, however, piston 260 moves toward the left and ultimately cuts off flow of air through valve 248. At this point, air is exhausted from cylinder 50 through port 270 and the knife returns. In the meanwhile, contacts 234 open, deenergizing solenoid 240. The spool of valve 242 shifts, and line 246 then communicates through valve 242 with exhaust port 272. At this time, the pressure in line 246 and in line 252 is approximately atmospheric and air in cylinder 258 can exhaust through line 256, line 266, check valve 268, line 252, line 246, valve 242 and port 272.

Whenever an edge of fabric passes the photocell, the apparatus just described imparts a quick downward movement to the knife and effects a quick return thereof automatically. The duration of time throughout which the knife remains down is determined through adjustment of restriction 254.

FIG. 9 shows the control system which effects operation of the various air cylinders and other parts of the apparatus described so far.

A high pressure air supply line 274 provides air for

cylinders

200, 210, 126, 128, 70 and 204 all of which are shown diagrammatically in FIG. 9. These cylinders are all of the spring-returned type. In addition, air is provided for clutch 188 and for air tube 120 through this line.

Delivery of air to the cylinders and to clutch 188 is controlled by solenoid-operated

spool valves

276, 278, 280, 282 and 284. The control system comprises three

interval timers

286, 288 and 290. An interval timer closes a load circuit immediately upon the start of an adjustable time period. The load circuit is closed during the time that the timer is running for the pre-selected period. When this is completed, the load circuit opens and the timer automatically resets. A suitable interval timer is the series PAF available from Industrial Timer Corporation of Parsippany, New Jersey.

The control system also includes a pair of

delay timers

292 and 294. The delay timer is a motoroperated device which switches a set of contacts from one position to another at the end of a predetermined interval following its energization. The contacts remain in the operated condition until power is removed from the energizing terminals of the delay timer. The timer is automatically reset when power is removed. The series 90 timers available from Industrial Timer Corporation are typical delay timers.

Terminals

296 and 298 are the main power terminals of the circuit and are supplied with alternating current. Main power switch 300 connects terminal 296 to line 302 which delivers electrical power to all three of the interval timers.

Switch 304 is a start switch operated by a foot pedal for momentary actuation by the machine operator. It delivers power to line 306 energizing relay coil 308 to effect closure of

relay contacts

210 and 312. Contacts 310 connect power from line 302 to coil 308 thereby providing a holding circuit not only for relay 308 but also for a clutch coil 314 which, when energized, effects a mechanical connection between motor 316 and a spring-loaded shaft which effects opening of switch 318 after a certain amount of rotation which is mechanically adjustable. The motor is energized through switch 320 which is closed whenever the clutch coil is energized.

Whenever switch 304 is closed momentarily,

relay contacts

310 and 312 close immediately and remain closed until switch 318 is opened. At that point, relay coil 308 and clutch coil 314 are de-energized. At that time, the shaft which operates switch 318 is spring returned to its initial condition to make the timer ready to begin a new cycle.

Timers

288 and 290 are identical to timer 286 with the exception of differences with respect to their preadjusted timing intervals. Timer 288 controls external circuitry through closure of contacts 322. Timer 290 controls external circuitry through closure of contacts 324.

Delay timer 292 comprises a motor 326 and a singlepole double-throw switch 328 operated thereby. Switch 328 is shown in its normal position. When

lines

330 and 332 are energized, the motor begins to operate, and after a predetermined delay, switch 328 disconnects line 330 from line 334 and connects line 330 to line 336. Switch 328 remains in this condition until power is removed from line 330, whereupon it returns to the condition in which it is shown, ready for another cycle.

Delay timer 294 is identical and comprises motor 336 and switch 338.

Line 340 is connected to power terminal 298 and, with line 302, delivers electrical power to the various parts of the circuit. Line 342 connects terminal 298 to timer motor 316. Line 344 connects terminal 298 to solenoid 346 which operates solenoid valve 276. The opposite terminal of solenoid 346 is connected through line 334 to the normally closed terminal of switch 328.

One terminal of solenoid 348, which operates valve 278, is connected through line 350, line 332 and line 344 to terminal 298. The opposite terminal of solenoid 348 is connected through line 336 to the normally open contact of switch 328.

Line 352 connects line 340 to timer 288. Line 302 is connected to line 354, the line through which the coils of timer 288 are energized, through microswitch 222, which is operated momentarily upon return of the piston of cylinder 210. A manually operable switch 356 is connected in parallel with microswitch 222. This switch may be used in adjusting the time interval provided by timer 288. Solenoid 224 (also shown in FIG. 6) is connected between

lines

354 and 340 so that, when microswitch 222 operates as cylinder 210 is released, solenoid 224 produces a sharp upward pull on clutch lever (FIG. 6).

Motor 336 of delay timer 294 is connected to line 340 through line 358. The other terminal of motor 336 is energized through line 360 and contacts 322 of interval timer 288. Solenoid 362, which operates valve 280, is energized from line 358 and from the normally closed terminal of delay timer switch 338. Solenoid 364, which operates valve 282 is energized from line 358 and from the normally open terminal 366 of switch 338.

The needle positioner, which comprises motor 166 and switch 368 is energized through line 360 and through

lines

358, 370 and 372. Whenever timer contacts 322 are closed, motor 166 operates the sewing machine until switch 368 opens. Switch 368 is operated by a cam (not shown) which rotates with shaft 168 (FIG. and which is so positioned with respect to the shaft that switch 368 opens only when the sewing machine needle is in a raised position.

Solenoid 374, which is also shown in FIG. 5, lifts the presser foot and releases the tensions when it is energized. It is energized from line 340 through line 376, and through line 378 from line 360. It is arranged to operate microswitch 380 momentarily when it is deenergized, by means of a hinged tab 381 fastened to the armature of the solenoid. The hinge prevents switch 380 from being actuated on the downward stroke of the armature of solenoid 374.

Switch 380 connects line 302 with line 382 through which the coils of interval timer 290 are energized. Solenoid 384 which operates valve 284 is energized through line 340 and through contacts 324 of timer 290.

Operating power for interval timer 386 is delivered through

lines

388 and 390. Microswitch 394 is operated momentarily upon return of the piston of cylinder 204. It initiates operation of timer 386 energizing solenoid 396 for a short interval. Solenoid 396 when energized, opens valve 398 delivering air to tube 120 from line 274 through line 400.

Operation of the control system of FIG. 9 will be best understood by reference to FIG. 4 which shows the sequence of operation of the timers.

When switch 304 is closed momentarily, timer 286 immediately begins to operate, and its contacts 312 remain closed for a period which might typically be about 6 seconds, although it may be varied depending on the length of the sash belt being operated upon. Solenoid 346 is operated, and cylinder 200 is supplied with air through valve 276. Cylinder 200 effects a partial downward movement of the clutch lever resulting in a partial engagement of clutch 148, producing slow sewing for a short period of time to allow for proper operation of the knife.

Following this short delay (which is typically one second as determined by delay timer 292) switch 328 operates, connecting line 336 to line 330 and thereby delivering power to solenoid 348. Air is delivered through valve 278 to cylinder 210, which pulls lever 150 downwardly far enough to effect full engagement of the clutch. Fast sewing proceeds until the end of the interval established by timer 286. At that point, the opening of contacts 312 removes power from

solenoids

346 and 348, and

valves

276 and 278 respectively return to a position providing for an exhaust path for air from

cylinders

200 and 210. These cylinders are preferably spring-loaded so that they return automatically. The return of the clutch lever, however, is aided by solenoid 224 which becomes energized when microswitch 222 is operated (see FIGS. 6, 7 and 9).

Momentary closure of microswitch 222 initiates operation of interval timer 288 at this point. Its interval is adjusted typically for about three seconds. Contacts 322 immediately close initiating operation of delay timer 294. Switch 338 operates about a second after the operation of switch 322. At the beginning of this one-second interval solenoid 374 operates, releasing the presser foot and the thread tensions. The solenoid remains energized until the end of the interval established by timer 288. Also during the one second interval, prior to the closing of switch 338, solenoid 362 operates valve 280 which delivers air to

cylinders

126 and 128. Their operation produces slack respectively in the needle and looper threads (see FIG. 8). In addition, the needle positioner may operate when contacts 322 of timer 288 close. The needle positioner requires only a fraction of a second for its operation.

When contacts 338 operate, solenoid 364 is energized. Energization of solenoid 364 operates valve 282 which delivers air to cylinder and to air-operated clutch 188. The air cylinder pushes downwardly on roller 58 to insure a positive pull on the fabric. The air operated clutch connects motor 192 to input shaft 94 of gearbox (FIG. 5). At this time, the roller 58 and the conveyor are operated by motor 192 rather than by the sewing machine motor. This operation produces the skip, and takes place until the end of the interval established by timer 288, at which point the opening of contacts 322 removes current from

solenoids

364 and 374. Air is released from cylinder 70 and clutch 188 disengages. Switch 380 operates momentarily upon the return of the armature of solenoid 374. At this point, the presser foot is down and the tensions are operative. Momentary closure of microswitch 380 initiates operation of timer 290 and closure of its contacts 324 energize solenoid 384, operating valve 284 to deliver air to cylinder 204. Cylinder 204 pulls the clutch lever fully downward to engage the clutch, and a second sewing operation takes place until the end of the interval established by timer 290. At that point, cylinder 204 is released, and the clutch is disengaged. Switch 394 of timer 386 operates initiating a short interval during which solenoid 396 opens valve 398 to deliver a blast of air through tube 120. This blast blows the sash belt onto a rack located at the bottom of the conveyor.

FIG. 2 shows the product produced by the machine just described. It comprises a piece of fabric folded at 402, and having its

longitudinal edges

404 and 406 together and even with each other. The first seam formed by the machine is indicated at 408. It extends from end 410 of the belt to the beginning of the gap 412 at 414. The gap ends at 416 at which point the second seam 418 begins. Seam 418 terminates at the opposite end 420 of the belt. To produce a finished belt, the ends are shown closed, and the belt is subsequently turned on a conventional turning machine. The gap is necessary for the turning operation.

The stitching is shown in detail in FIG. 3 which shows

edges

404 and 406 of the fabric, and which shows how the stitches are separated at gap 412. A two-thread chain lockstitch is preferably used because it can be produced without the necessity for frequent thread replacement, and it resists ravelling. However, the conventional lockstitch, or other stitches may be used.

The apparatus just described is useful primarily in the production of sash belts, although it can be modified for producing other articles wherein a skip between seams is required. The only operation required by the human operator is the introduction of fabric into the V-folder and the initiation of the timer sequence by actuation of switch 304 (FIG. 9). Therefore, it is entirely feasible to provide one operator with two or possibly three machines which may be operated simultaneously. The total time for sewing a 66 inch sash belt is typically about 12 seconds. With two machines,

a single operator can produce more than 2,800 belts in an 8 hour day. The machine produces sash belts of high quality. The product is consistent in width and free of pucker.

I claim:

1. A sewing machine having a reciprocating needle, means cooperating with said needle and means for moving two layers of fabric past said needle and said cooperating means, to produce a seam for securing together said two layers of fabric, control means for effecting simultaneous operation of said needle and said cooperating means to produce a first seam, having a predetermined length, thereafter effecting movement of said layers of fabric without stitching by said needle and its cooperating means for producing a gap of predetermined length, and thereafter effecting continued stitching by said needle and cooperating means to produce a seam on the other side of said gap, and

tension means for producing a tension in a length of thread approaching the location of the needle, and means responsive to said control means for producing a slack in the thread between said tension means and the location of said needle following the completion of said first seam and prior to the production of said gap.

2. A sewing machine having a reciprocating needle, means cooperating with said needle to produce stitching for securing together two layers of fabric, a presser foot, feeding means normally cooperating with said presser foot to move said layers of fabric past said needle and said cooperating means, timer-operated control means for effecting simultaneous operation of said needle, said means cooperating with said needle and said feeding means for a first predetermined interval to produce a first seam, thereafter discontinuing cooperation between said presser foot and said feeding means for a second predetermined interval to allow said fabric layers to be moved past said needle and its cooperating means to produce a gap, and thereafter effecting continued simultaneous operations of said needle, said cooperating means and said feeding means to produce a seam on the other side of said gap, and means responsive to said control means for moving said fabric layers past said needle and its cooperating means during the second predetermined interval.

3. A sewing machine according to claim 2 in which the means responsive to said control means for moving said fabric layers during the second predetermined interval comprises roller means positioned to receive said fabric layers after they pass said feeding means and normally exerting a pressure against the fabric sufficient to take up slack between said feeding means and said roller means but allowing some slippage at said roller means, and means causing said roller means to exert a greater pressure on the fabric during the second predetermined interval.

4. A sewing machine having a reciprocating needle, means cooperating with said needle to produce stitching for securing together two layers of fabric, a presser foot, feeding means normally cooperating with said presser foot to move said layers of fabric past said needle and said cooperating means, control means for effecting simultaneous operation of said needle, said means cooperating with saidneedle and said feeding means to produce a first seam having a predetermined length, thereafter discontinuing cooperation between sai presser foot and said feeding means to allow said fabric layers to be moved past said needle and its cooperating means to produce a gap of predetermined length, and thereafter effecting continued simultaneous operation of said needle, said cooperating means and said feeding means to produce a seam on the other side of said gap, and means responsive to said control means for moving said fabric layers past said needle and its cooperating means to produce said gap' 5. A sewing machine according to claim 4 in which said means responsive to said control means for moving said fabric layers includes roller means positioned to receive said fabric layers after they pass said feeding meansand normally exerting a pressure against the fabric sufficient to take up slack between said feeding means and said roller means but allowing some slippage at said roller means, and means causing said roller means to exert a greater pressure on said fabric during the production of the gap.

6. A sewing machine according to claim 4 including a first motor for operating said reciprocating needle and said means cooperating with said needle, a second motor, roller means positioned to receive said fabric layers after they pass said feeding means and exerting a pressure against said fabric sufficient to take up slace between said feeding means and said roller means, means responsive to said control means connecting said roller means to said first motor for rotation thereby during the production of said seams, and for connecting said roller to said second motor for rotation thereby during the production of said gap.

Claims

1. A sewing machine having a reciprocating needle, means cooperating with said needle and means for moving two layers of fabric past said needle and said cooperating means, to produce a seam for securing together said two layers of fabric, control means for effecting simultaneous operation of said needle and said cooperating means to produce a first seam, having a predetermined length, thereafter effecting movement of said layers of fabric without stitching by said needle and its cooperating means for producing a gap of predetermined length, and thereafter effecting continued stitching by said needle and cooperating means to produce a seam on the other side of said gap, and tension means for producing a tension in a length of thread approaching the location of the needle, and means responsive to said control means for producing a slack in the thread between said tension means and the location of said needle following the completion of said first seam and prior to the production of said gap.

4. A sewing machine having a reciprocating needle, means cooperating with said needle to produce stitching for securing together two layers of fabric, a presser foot, feeding means normally cooperating with said presser foot to move said layers of fabric past said needle and said cooperating means, control means for effecting simultaneous operation of said needle, said means cooperating with said needle and said feeding means to produce a first seam having a predetermined length, thereafter discontinuing cooperation between said presser foot and said feeding means to allow said fabric layers to be moved past said needle and its cooperating means to produce a gap of predetermined length, and thereafter effecting continued simultaneous operation of said needle, said cooperating means and said feeding means to produce a seam on the other side of said gap, and means responsive to said control means for moving said fabric layers past said needle and its cooperating means to produce said gap.

5. A sewing machine according to claim 4 in which said means responsive to said control means for moving said fabric layers includes roller means positioned to receive said fabric layers after they pass said feeding means and normally exerting a pressure against the fabric sufficient to take up slack between said feeding means and said roller means but allowing some slippage at said roller means, and means causing said roller means to exert a greater pressure on said fabric during the production of the gap.