CA1179900A

CA1179900A - Sheet production system with hem expander

Info

Publication number: CA1179900A
Application number: CA000380197A
Authority: CA
Inventors: Charles E. Brocklehurst
Original assignee: Opelika Manufacturing Corp
Current assignee: Opelika Manufacturing Corp
Priority date: 1981-06-19
Filing date: 1981-06-19
Publication date: 1984-12-27

Abstract

SHEET PRODUCTION SYSTEM
WITH HEM EXPANDER

Abstract of the Disclosure Sheet material is taken from a supply, moved along its length to a cutting station, the sheet material is cut into segments, and the cut segments are moved parallel to their cut edges, the cut edges are hemmed, and the segments are folded. At the cutting station the leading portion of the sheet material is gripped and pulled from the entrance to the cutting station to the other side thereof, a slack bar is moved downwardly into the segment of sheet material in the cutting station to form slack in the segment, and the segment in the cutting station is clamped against parallel conveyor tapes.
A cutting disc is drawn across the sheet material at the entrance to the cutting station, and the parallel conveyor tapes move the sheet parallel to its cut edges to a hemming station where the edges are folded and hemmed. The hems of the side edges are expanded after being mechanically formed and prior to being sewn. The leading and trailing edges of the folded portions of the hems are aligned with the leading and trailing edges of the unfolded portion of the hem as the segment approaches the sewing machine.

Description

l 17990~

SHEET PROD~CTION SYSTEM WITH HEM EXPANDER
Technical Field This invention relates to the manufacture of bed sheets and other sheet material wherein sheet material is moved from a supply along its length to a cutting station, the sheet material is cut into segments, and the cut edges of the segments are hemmed as the segments are moved along a path parallel to their cut edges.
Backgroun In the production of sheet material, such as bed sheets, curtains, bed spreads, etc., the goods usually are cut from a supply of sheet material and the cut edges are hemmed. In some situations the side edges of the cut segments of sheet material do not need to be hemmed since the side edges comprise a selvage of the sheet material. Thus, only the cut edges need to be folded and sewn into a hem.
Various automatic machines have been developed and used for cutting and hemminy sheet material. For example, U.S.
Patent Nos. 3,580,198, issued May, 1971 to Teed et al; 3,640,235 issued February, 1972 to Burton; 3,772,948, issued November, 1973 to Burton; 3,906,878, issued September, 1975 to Burton and 3,955,515, issued May, 1976 to Elsas all illustrate systems which appear to be capable of automatically cutting segments from sheet material and hemming the cut edges of the segments. How-ever, it is understood that the prior art devices have e~perienced some difficulty in controlling the cut edges of the segments of sheet material as the cut edges are being moved to and through a hemmer. This difficulty is increased when a large hem is to be formed at the cut edge of the segment of sheet material. For example, the large hem at the head of a bed sheet usually is visible when in use by the purchaser, and it is desirable to have this hem formed with a constant width, so that it is uniform and attractive to the purchaser. However, when the hem at the head of a bed sheet is formed with automatic hem forming equip-ment, it is difficult to control the wide expanse of folded material so as to accurately and rapidly form the hem.
D

2 l 179g00 Summary of the Invention The invention in one broad aspect pertains to a method of forming a hem in sheet material comprising the steps of folding an edge portion of the sheet material into overlying relationship with the body of the sheet material, holding the edge portion from movement in a direction across its length, positively moving the body of the sheet material toward the fold in the sheet material, directing a flow of fluid toward the fold between the layer of the folded edge portion and the layer of the body of the sheet material to expand the folded portion of the sheet material, and sewing through the folded portion and the body portion of the sheet material to form a hem.
The invention in another aspect comprehends a method of forming a hem in the edge of a segment of sheet material comprising moving the segment along a path with the edge portion to be hemmed extending along the path, folding the edge portion upwardly into overlying relationship with the body portion of the segment, simultaneously moving the folded over portion with an upper belt member toward a sewing machine and moving the body portion of the segment beneath the folded over portion with a lower belt member toward the sewing machine, and in response to detection of an on-coming edge of the segment approaching the sewing machine shifting the phase of one of ~he belt members to change the position of the on-coming edge of the body portion 2S of the segment beneath the folded over portion with the on-coming edge of the folded over portion, and sewing through the over-lying folded over portion and the body portion of the segment beneath the folded over portion.
The invention further comprehends apparatus for forming a hem in the edge of a segment of sheet material compris-ing means for moving the segment along a path with the edge portion to be hemmed extending along the path, a fold platform extending along the path and spaced over the path, means for folding the edge portion upwardly from thè path onto the top surface of the fold platform in overlying relationship with re-spect to the body portion of the segment, upper belt means for engaging and moving the folded over portion of the segment at a position on the platform to a position beyond the end of the D

2a ~1799~0 platform, and lower belt means for engaging and moving the body portion of the segment from beneath the platform to a position beyond the end of the platform, detecting means for detecting the on-coming edge of the segment, and phase shifting means responsive to the detecting means for shifting the phase of one of the belt means to momentarily change the velocity of the one of the belt means with respect to the other of the belt means.
In another aspect the invention pertains to apparatus for hemming sheet material wherein a segment of sheet material is moved on a work surface along a path in a direction parallel to an edge of the sheet material which is to be folded and sewn into a hem. The improvement in the apparatus includes a fold platform mounted in spaced parallel relationship with respect to the work surface over the path of the segment of sheet material with an edge portion extending along the path of the segment of sheet material. Folding means ls provided for folding the edge portion of the segment of sheet material upwardly from beneath the fold platform about the edge portion of the fold platform and onto the top surface of the fold platform in overlying relationship with respect to the body portion of the segment of sheet material.
Means are movable downwardly against the edge portion of the segment of sheet material on the top surface of the fold platform for moving the edge portion along the fold platform and for holding the edge portion from movement in a direction across its edge.
A movable surface is adjacent the fold platform and is positioned vertically with respect to the path of the segment of sheet material. Clamp means clamp the body portion of the segment of sheet material against the movable surface and means move the movable surface toward the fold in the segment of sheet material.
Means are provided for directing a flow of fluid from beneath the fold platform toward the fold in the segment of sheet material to expand the folded portion of the segment of sheet material.
More particularly, the invention as disclosed comprises a sheet production system with a hem expansion attachment, where-in sheet material is moved from a supply along its length towarda cutting station, the sheet material is cut into segments at the cutting station, and the cut segments are moved parallel to their cut edges and the cut edges are folded. The fold at one end of the cut segment is expanded to a large size, and the ~ 179~00 enlarged fold is sewn to the body portion of the cut segment.
A qripper moves across the cutting station to the entrance of the cuttinq station to qrip the previo~sly cut leadina edge of the sheet material and then moves bacK across to the far side of the cutting station, pullin~ the sheet material over a pair of parallel conveyor tapes into the cuttinq station. A
slack bar moves down into the seqment of sheet material between the parallel conveyor tapes at the cuttinq station, causinq slack to be formed in the seqment, and a cla~ at the entrance of the cutting station qriDs and holds the segment in ~osition while conveyor clamps move down toward the conveyor tapes to clamp the segment of sheet material against the conveyor tapes. A disc cutter is then drawn across the sheet material at the entrance of the cutting station, to cut the segment away from the supply of sheet material. The gripper then releases the cut seqment and the conveyor tapes move the cut segment in a direction Parallel to its cut edges at a high velocity on into the hem folding and expansion station.
The cut edges of the seq~ent are proaressively folded as they move into the foldin~
and expansion station, and after the cut edges have been folded, one folded edge portion of the cut seqment is expanded to the desired width for the hem.
The seqment of sheet material is then moved at a slower s~eed on through a sewing station where the folded edqe portions are sewn to the body of the sheet material, thus forming the hems at the head and foot of the bed sheet. If desired, the system can employ hem expanders for both hems.
After hemminq, the seqment of sheet material, which is now sewn in the form of a final 4 1 179gOO

product such as a bed sheet,is folded for shipment and ultimate sale to the customer.
This invention in one aspect seeks to provide a hem expander attachment for a sheet production system, which accurately forms the large hem in the head of a bed sheet or a large hem in other sheet products, and in another aspect to provide a hem expander attachment for a sheet production system wherein a fold is made in the edge portion of the sheet material, and the fold is subsequently expanded.
Other aspects, features and advantages of the present invention will become apparent upon reading the following specification, when taken in conjunction with the accompanying drawings.

Brief Description of the Drawin~s Fig. 1 is a schematic perspective illustration of the sheet production system.
Fig. 2 is a perspective illustration, with parts removed for clarity, of the supply, cutting, s expansion an~ hemminq stations of the sheet product ion system.
Fig. 3 is a perspective detail illustration of the cutter.
Figs. 4--6 are progressive schematic side elevational views of the cuttinq station, with ~igs.
4 and 5 illustratina how the sheet material is griPped and pulled across the cutting station, with Fig. 5 illustrating how slack is formed in the sheet material, and with Fig. 6 illustrating how the secment of sheet material in the cutting station is cut from its supply and ho~ the conveyor tapes and conveyor clamps function to move the cut segment from the cuttinq stàtion toward the expansion station.
Figs. 7--9 are progressive schematic illustrations of the entrance to the expansion station, with Fig. 7 illustrating how the sheet material is moved to the expansion station and with Figs. 8 and 9 illustratin~ how the opposite c.lt edge portions are initially folded,Fig. 7 a~earing with Fig. 1 Fiqs. 10--12 are progressive schematic illustrations of the hem expander, with Fig. 10 illustrating the movement of the sheet material throuqh the hem expansion station, with Fig. 11 illustr~tin~ the way in which the hiem is exoanded, antl with Fiq. 12 illustrating the way in which the sheet mater ial is moved beyond the hem expans ion sta t ion .
Fig. 13 is a perspective illustration of the folder which forms the hem at the head of the bed sheet as 'che sh~et moves from the cutting station into the expansion station.
Fig. 14 is a perspective detail illustration of a portion of the hem expander attachment.

1 1799Q`O

_ Fig~ lS illustrates the end Dortion of the hem ex~ansion attachment and the sewing station and its control means for carrying the folded hem of the Fsheegt ~aterial on throuqh a sewing machine,-appe~ ~g with Fig. 16 is a side view of the end portion of the hem exoansion attachment and a portion of the sewinq station.
Fiq. 17 is a sche~atic illustration of the drive svste~ for the cutting, expansion and hemmin~
stations, appearing with Fig. 14.
Fiqs. 18A and 18B are co~posite electrical ~iaqrams of the control system for the cutting, expansion and hemminq stations.
Fi9~ 19 is a time graph showing the lS se~uence of operation of the switches actuated by the cam system.
Fig. 20 is an electrical diaqram of the contr~l system for the lower transfer belt that adjusts the align~ent of the leading and trailing edges of the hem and the main body of the segments of shee' ~terial as the hem moves into the sewinq machine.

Detailed DescriPtion Referrinq now in more detail to the drawings, wherein like numerals indicate like parts throughout the several views, Fia. 1 schematically illustrates the sheet production system 20, wherein sheet material 21 is taken from a supply such as from reel 22 and fed in an upward direction 24 by a driven feed roller 25 at an inspection station, where a worXer inspects the sheet mate~ial for flaws, etc.
The ~laws are marXed with a liquid so that the flaws can be detected at the cuttin~ station and the cut se~men' which includes a-flaw can be identified. A

7 1.179gOO
particular sheet inspection and marking system suitable for use in this invention is disclosed in U.S. Patent 4,204,012 issued May 20, 1980 to Brocklehurst et al.
The sheet material moves beyond driven roll 25 and then through a serpentine path about upper stationary rolls 26 and lower movable rolls 28. The lower movable rolls are mounted on lever 29, and the lever 29 pivots about fulcrum 30. Thus, the upper and lower rolls 26 and 28 function as an accumulator 31 for the sheet material, to accommodate an increasing or decreasing supply of the sheet matrial from the inspection station.
The sheet material moves from the accumulator 31 into cutting station 32. A cutter 33 is mov~ble across the sheet material to form cut segments 34. Slack 35 is formed in the sheet material at the cutting station 32 just prior to cutting the sheet material, so that the cut segments 34 have slack therein as they are moved parallel to their cut edges 36 and 38 through hem expansion station 39, and to hemming station 40, and then to pleat folder 41 and spiral folder 42.
The sewing machines and hemming attachments of the type used at hemming station 40 are illustrated in U.S.
Patent 3,906,878, issued September 23, 1975 to P. E. Burton, and the pleat and s?iral folders 41 and 42 are illustrated in U.S. Patent 4,227,684, issued October 14, 1980 to Brocklehurst. ~n improved needle lubrication system of the type disclosed in U.S. Patent No. 4,369,723 issued January 25, 1983 to Griffith, Jr. et al is used with the sewing machines in hemming station 40 in order to increase the speed of operation of the sheet production system. If it ls desired to place labels in the finished product, a label dispenser of the type disclosed in U.S. Patent 4,157,692 can be utilized at the hemming station 40.
As lllustrated in Fig. 2, the cutting ~ 179~00 station 3Z, the hem expansion station 39 and hemminq station 40 are all located in aliqnment with one another and utilize a single work table assembly 71.
Work table assembly 71 is a split worX table, with S left and ri~ht halves 72 and 74 which define an open space 7~ therebetween. Additionally, right and left halves 72 and 74 of the work table assembly 71 include cuttinq station seqments 72a and 74a which are divided from the expansion and hemming segments ~2b and 74b. The worX table halves 72 and 74 are movable toward ~nd away from each other to form the cut seament-s of sheet material in different len~ths.
This is accomplished with an electric motor and drive s~stem (not illustrated).
A conveyor tape assembly 7~ is located in and alo~q work table hal~ 72 while a similar conveYor taDe assembly 78 is located in and along work table 74. ~ince each worX table is broken at 79 and 80 to form a passaqe through the work table assembl~, thus forming the work table assembly in sections, the conveyor tape assemblies 76 and 78 are also broken a~
passageways 79 and 80, with the conveyor tape assemblies bein~ formed in sections 76a and 76b, and 78a and 78~. The conveyor tapes 76 and 78 are spaced from each other and are parallel to each other and extend at a right anqle with respect to the direction of movement of the sheet material 21 as the sheet material enters the cuttin~ station 32.
Cuttina ~tation Clamp assembly 81 (Fiqs. 2 and 4--6) is located at the entrance 83 of cutting station 32.
ClamP ~ssembly 81 includes upper frame 82 and lower frame 84 which are vertically spaced apart and which permit the passaqe therebetween of sheet material 21.
A rectilinear clamp bar 85 is mounted on the ends of ~ 179g~0 _ a plurality of cylinder rods 86, and a plurality of pneumatic cylinders 88 are mounted in the upper frame 82. The clamp bar 85 defines an elongated slot 89 in its bottom surface, and an elongated elastic tube 90 is mounted in the slot. Tube 90 protrudes from the bottom surface of bar 85 toward lower frame 84.
Lower frame B4 has an upper horizontal surface 91 over which the sheet material 21 moves, and against which clamp bar 85 and its tube gn bear. ~hen clamp bar 85 is moved to its down position by its cylinders 88, th~ clamp bar holds the sheet ~aterial 21 against the upper horizontal surface 91 of the lower frame 84, with the flexible tube 90 bearinq against the sheet material 21 and against the u~per horizontal surface 91.
Lower frame 84 includes platform 92 that extends toward cutting station 32. Movable support means 94 rests on platform 92 and comprises a rectilinear beam of inverted U-shaped cross sectional shape including top surface 95 an~ downward extending leqs 96 and 98. A plurality of guide pins 97 extend through both leqs 9fi and 98 of movable support means 94 and throuqh the upri~ht wall portion 100 of lower frame ~4. A coil compression sprin~ 101 surrounds that portion of each guide pin g9 between beam 94 and the upright wall w rtion 100 of lower frame 84, and the end heads 1~2 and 104 of the guide pins 99 limit the movement of the beam 94 away from the upright wall portion 100. Thus, springs 101 bias the movable suvport means 94 to the position illustrated in Figs.
4 and 5.
Grippinq bar 105 comprises a channel-sha~ed beam 106 which includes top wall 108, side wall 109 and bottom wall 110. Rectangular support beam 111 is mo~nted to the si~e wall 109 of channel beam 106 and ( ~ ~799~0 - supports the channel beam as illustrate~. A
plurality of pneumatic cylinders 112 are mounted to the top wall 108 of channel beam 106, and clamp bar 114 is su~ported by the cylin~er ro~s 115 of cylinders 112. The clam~ bar 114 is rectilinear and inclu~es a rectilinear slot 116 in this lower surface, and an elon~ated elastic tube 118 fits in the slot. The arrangement is such that the clamp bar 114 and its tube 118, functioning 25 an upper clamp member, are moved toward and away from the bottom wall 110, which functions as a lower clamp member, wherebv the assembly functions as a ~ripping means.

As illustrated in Fi~. 2, qripping bar 85 ~s mounted at its en~s on trolleys 119 and 120, with each trolley being supported by its wheels 121 on a trac~ 122. A continuous chain drive 124 com~rising chain 125, end sprockets 126 and 128 and air motor 129 function to move each trolley 119 and 120 along their tracks 122. Trolley 119 moves adjacent the end of work table sections 72a anfl 74a while trolley 12~
moves through the passaaeways 79 and 80 between the work table sections 72a, 72a, and 74a and 74b. Thus, gripping bar 85 can be moved back and forth across cuttin~ station 32 from the entrance thereof 83 to the other side thereof, ~7. It will be noted that the cl~mp assembly lOS is long enouqh so tha' it extends beyon~ the trolley 120 and beyond the passaqes 79 and 80 for~ed in the work table assembly-As ill~ustrated in Fi~. 4, when grippinq means 105 moves from its home position 88 across the cuttinq station 32 to the entranc~ ~3 of the cutt ing station, it moves into abutment with the movable support means 94, with the lower clamp mem~er 110 1. 179g~0 _ abuttin~ the leg 96 of the movable support means 94.
This causes the movable support means to move a~ainst the bias of its springs 101, so that the lower clamp member 110 moves in beneath the leadin~ edqe portion 21c of the sheet material 21. ~hen the qripping bar lOS is in this Position the uDper clamp member 114 is moved down by it~ pneumatic cylinders 112 so that the lea~ing e~qe portion 21c of the sheet material is gripped between the upper clamp member 114 and the lower clamp member 110. When the gripping bar then begins its movement from the entrance ~3 back to its home position 88, it pulls the sheet material 21 with it. In the meantime, clamp assembly 81 opens so as to allow the sheet mater~al 21 to pay out and move with clamp assembly 1 n s .
As illustrated in Fig. 2, the fra~ework of the work table assembly 71 includes parallel support beams 134 and 135 which extend from cuttin~ station 32 through hem expansion station 39 to hemming station 40. The parallel support beams 134 and 135 are sup~orte~ over work tables 72 and 74, and conveyor ta~e clamp bars 136 and 138 are supported from the support beams 134 and 135. Pneumatic cylinders 139 are spaced along support beam 134, and the cylinder rods 140 are connected to the support clamp bar 136, while pneumatic cylinders 141 are spaced alon~ support beams 135 and their rods 142 are connected to an~ support convoyor tape clamp bar 138.
The clamP bars 136 and 138 are positioned over the conveyor tapes 76 and 78 and are movable by their cylinders 139 an~ 141 down toward an~ abutment with the conveyor tapes. Thus, when she~t material 21 i5 extende~ across the cutting section 32 by ~ripping bar 1~5, the clamp bars 136 and 138 are movable down into en~aqement with the sheet material to ur~e the _sheet material into frictional contact with the conveyor taPes, so that when the conveyor taPes begin their move~ent, the sheet material will be moved with the conveyor tapes.
5Clamp bars 136 and 138 are broken into sections 136a and 136b, and 138a and 138b, with the sections 136a and 138a extendinq over the passa~es 79 an~ 8n between the segmented work table assembly, so that the end portions of the clamp bars 136a and 138a 10span the passaaeways 79 and 80. ~he sections 116b and 138b are aligned with the sections 136a and 13~a.
Slac~ bar assembly 144 is mounted on suPport beam 135 and includes rectilinear slack bar 15145 that extends parallel to conveyor tapes 76 and 78 and which is located in the central open space 75 between the halves of the work table ass~mbly, and L-shaPed suDport legs 14fi and 148, and rear connector bar 149. Clevises 150 and 151 pivotally connect the 20L-shaped support leqs 14~ and 148 to supoort beam 135. Pneu~atic cylinders 152 and 153 are mounted at the ends of rear connector bar 149 and function to pivot the slack bar assembly 144 about support beam 135, so tha~ its slack bar 145 moves down into the 25plane of the sheet stretched across the central open space 75 (Fig. 5).
As illustrated in Fi~s. 2, 3 and 6, cutter 33 comprises a rectilinear guide beam 154 which extends across the entrance 83 of the cutting station 3032 at the movable support means 94. A carriage 155 is mounted on cutter guide beam 154 and includes upper and lower brackets 156 and 158 mounted about the uPPer and lower surfaces of guide beam 154, and ~-sha~ed housinq 159 havinq its upper and lower legs 160 and 161 mounted to brackets 156 and 158. Cutter 1 1~9900 - disc 162 is ~ounted, by means of bearing 164, in the side wall 165 of U-shaped housin~ 159, with the axis of rotation of the c~tter extendinq in a horizontal plane and with disc 162 extendin~ in a vertical ~lane. A drive pulley 166 is connected to the disc ~rive shaft 168, and drive band 159 extends about pulley 166. A pa~r o' idler pulleys 170 and 171 direct the ~ide band 169 around approximately 180-of the drive pulley 16~, causing the drive band to 1 frictionally en~a~e and rotate drive pulley 166.
Reversible electric motor 172 is mounted at the end of cutter guide beam 154, and its driven pulley 174 has drive band 169 wrapped therearound. The band is also wrappe~ around idler pulley 175 ~Fig. 2) at the other end of the cutter quide beam 154. Thus, when electr~c motor 172 is energized, the movement of band 169 along its length causes disc 162 to rotate.
Carriage conveyor belt 176 is mounted at its ends about pulleys 178 and 179, and the pulleys 17B and 179 are mounted to the ends of cutter ~uide beam 1~4 by means of suDport straps 180. Reversible air motor 181 has its output shaft connected to pulley 179 and is arran~ed to drive carriage conveyor belt 176. ~arriage conveyor belt 176 is connected to the top surface of carria~e 155, so that movement of the carriage conveyor belts causes carriage 155 to traverse cutter guide means 154 and move cuttin~ disc 162 across the sheet material.
As is illustrated in Figs. 2, the second pair of conveyor tape assemblies 18Z and 184 are located in the hem expansion section 39 of the assembly, with the conveyor tape assemblies 182 and 184 bein~ located Darallel to and outside the conveyor taPes 7fib and 78b. Convey~r tape clamp bars 185 and 186 are located over conveyor tapes 182 and l~79900 _ . 184, with the pneumatic cvlinders 188 and their rods 189 supportinq clamp bar 185 and with the pneumatic cylinders 190 and their rods 191 supportin~ clamp bar 186. The clamp bars 185 an~ 186 are supported directly over conveYor tapes 182 and 184 and are movable down toward and up away from engaqement with the conveyor tapes and the sheet .~aterial carried thereon.
As illustrate~ in Fiq. 5, the conveyor tape clamp bars, such as clamp bars 136 and 138, each include a rectilinear bar 204, a plurality of vertical hol~s formed vertically through the bar (not shown), and pins 205 extending downwardly through the holes of the bar, with the heads 206 of the pins restina on the uPper surface of the bar 204, and with the stems 208 extending down beneath the bars 204. A
slide or foot 209 is mounted on the bottom of pins 208, and a coil comPression sprin~.210 surrounds each pin 208 beneath bar 204, and biases the foot downwardly away from the bar 204. The conveyor ~ape ~ P bars 136 and 138 are moved to their up posi~ions by their cylinders 139 and 141 when griDping means 105 moves as indicated by arrow 211 away f~om the entrance 83 of the cutting station 32 to its home Position 87. After the gripping member ~as reached its'home position 87, the clamp bars 136 and 138 move down toward engagement with the sheet material 21, over conveyor tapes 76 and 78. Cutter 33 is then energized, by air motor 181 movin~
carriaqe conveyor belt 17fi, causing the carria,ge 155 and disc cutter to move along the length of cutter guide beam 154. In the meantime, e;ectric motor 172 is enerqize~ to move its drive band 1~9 about drive pulley 16~ of disc cutter 162, causing disc cutter 162 to rotate. Thus, the sheet material will be cut ~ 1 ~9 `' _ by cutter 33 when qripping means 105, clamP bars 136 and 138 and clamp assembly have all engaged the sheet material 21, thereby holding the sheet material in a stable condition.
After the cutter has completed the cut across the sheet material to form the cut segment 34, qripping means 105 releases the sheet material 21 and the conveyor tapes 76 and 78 begin their movements, to move the cut segments 34 in a direction parallel to the cut ends of the segment from the cu~ting station 32 to the hem expansion station 39.
Hem Forminq and Expansion Attachment Conveyor tapes 76a and 76b (~igs. 2, 5 and 6) move the cut segment 34 of sheet material from the cuttinq station 32 on into the hem expansion station 39. Outside conveyor tapes 221 and 222 move UD into supporting relationship from the work table (Fi~s. 7 and 13) to support the cut edqe portions of the cut segment as they enter folders 224 and 225 . 20 As illustrated in Fig. 13, each folder includes a fold finger 226 that is supported in parallel, spaced relat~onship with respect to the work surface of the work table by support bracket 228, and includes an edge 229 that extends approximately parallel to the cut edge 36 of the cut se~men~ 34 of sheet material, and an angled edge 230.
Stationary edge folder 231 is attached to the work surface and extends upwardly and curves about edges 229 and 230, and generally conforms to the shapes and a~qles of the edges 229 and 230. The stationary edge folder functions like a plow in that it lifts and turns over the cut edge portion 220 of each segment 34, so that the cut edge portion is folded over and on top of fold finger 226. The shape of edge folder 231 causes the material to be progressively moved t~79g~0 _ onto the fold finger 226.
As illustrated in Fig. 13, foldinq band 232 moves uDwardly from its sheave 234 through an opening in the work surface and moves into the edge folder 231. The edqe folder 231 includes a slot 235 into which the band initially moves, and the band 232 is quided over the edge 22~ o~ the fold fin~er 22fi and extends at a.n angle inwardly of the angled edge 230 of the fold finger. Pullev 2?7 is located at the end of fold finger 226 and takes up folding band 232.
Guide bracket 239 is ~ocated immediately in front of the sheave of pulley 237 that receives folding band 232, assuring that the band tracks directly toward the groove of the p~lley 238. ~n its return flight, foldin~ band 232 is gu~ded over fold finger 226 by sheave 240, then moves ~ownw~rdlv through an opening in the work surface, about another quide pulley (not shown), bacX to sheav~ 234. The guide Dulley ~elow the worX surface is driven to impart movement to the folding band. The arran~ement of foldin~ band 232, fold finaer 226 and outer belt 221 causes the cut edge portion 220 of the segment of sheet material to be proaressively and PoSitivelv folded over into overlyin~ relationship with respect to the body portion of the seq~ent of sheet material.
As illustrated in Figs. 13 and 14, fold Platfor~ 241 is also supported in spaced, parallel relationship with respect to the work surface 72b, by means of vertically extending sup~ort plate 242 connected at its lower edae to an edge of the fold ~latform 241, and by L-shaped support brackets 244 attached to the upper ~ortion of the vertical support plate 242 a~ space~ intervals alon~ its length, and to worX table 72b. Fold platfor~ 241 includes a rectilinear folding edge 245 that extends the entire ~. 179gOO

_ lenath of he~ expansion section 39, and fold finqer 226 ahuts the entrance end of fold platform 241, so that the angled edqe 230 of fold finger 226 merges with the rectilinear ed~e 245 of fold platform 241.
S Thus, the cut edqe portion 220 of the se~ment of sheet material 34 moves off fold finger 226 onto fold platform 241.
As illustrated in Fig. 13, platfor~ belt 246 extends abou~ pulley 238, and pulle~ 238 moves the platform belt down into enqa~ement with the cut and folded over e~qe portion 220 of the sheet material as t~e cut edge portion moves on the upper surface of fold platform 241. Platform belt clamp 248 is positioned over fold platform 241 and is located on top of the lower fl iqht of platform belt 24~. A plurality of support rods 249 are mounted to vertical support plate 242 and extend horizontall~
between the upper and lower flights of platform belt 246, outwardly over the ~latform belt clamp 248.
Each su~Dort rod 249 is rotatablv supported in its mount 250, and a set screw 251 extends through the mount 250 and holds the support rod 249 in place.
The distal end of each support rod 249 is bifurcated~
and a leaf sprin~ 252 extends through the slot of the bifurcated distal end. Each leaf spring is also ri~i~ly connected at one of its ends to the upper surface of platform belt clamp 248. Thus, the platform belt clamp is supported at spaced intervals alon~ its length by the leaf springs 252 and support rods 249 and their mounts 250 from vertical support plate 242.
When ~ore or less downwar~ force is to be applied by the platform belt cl~mp 248 against the platform belt 246, the set screws 251 can be loosened and the support rods 249 turned to change the force applied to the leaf sprinas 252. Thus, the platform belt 246 exerts a movinq clamp action to the cut edqe portion 220 of the cut segment of sheet material 34 as the cut segment moves along fol~ platform 241, S thus holdinq the cut ed~e portion from movement in a direction across its cut edge as the cut edge portion moves alon~ the fold platform 241. Platform belt 246 is driven at the same linear speed as band belt 76 as the cut segment of sheet material moves into the hem expansion section 39, thus assurinq that no wr inkles will be formed in the sheet material.
As illustrated in Figs. 10--12 and 14, a plurality of slots 255 are formed in fold platform 241 at spaced intervals along the length of the fold platform. The slots 255 are elongated and are aligned with one another along the length of fold platform 241. Slots 255 are positioned ~etween vertical sl~pport Plate 242 and platform belt 246 and its clamp 248. An elongated roller assembly 256 is located beneath the surface of work table 72b and includes an axle 258 extending parallel to slots 25S, and a plurality of bands 259 are mounted on axle 258 at spaced intervals along the length of the axle.
The bands 259 are located beneath the slots 255 in fold platform 241. The bands 259 are also located in slots 260 formed in work tahle 72b, with the slots 260 being positioned beneath the slots 255 in fold platform 241.
A pl~rality of expansion clamps 262 are suspended above fold platform 241 over slots 255 in the fold Dlatform. Each expansion clamp 262 is l,-shaPed in cr~ss section and includes horizontal leg 264 and vertical leg 265. ~:ach expansion clamp 262 is of a length and width sl iqhtly less than the length and width of the slot 255 in fold platform 1 179g~0 _ 241. Each expansion clamp 262 is supported by cylinders 266 and their rods 268, with the cylinder rods beina attached to the vertical lec 265 of a clamP 262. Each cylinder 266 is mounted by means of S a bracket 269 to vertical support plate 242, and the cylinders 256 include an internal coil compression sprin4 (not shown) that holds its cylinder rod 258 in a retracted, up position. Controlled air pressure communicates with the upper end of each of the 1~ cylin~lers 266 through conduits 270. Thus, cyl inders 266 function to reciprocate expansion clamps 262 between a Position where the expansion clamps 262 are retracted above the slots 255 of fold platform 241 ~Fias. 10, 12 and 14) and to a DOsition where the expansion clamps are moved downwardly through the slots 255 in fold platform 241 and bear aqainst the upper surfaces of elon~ated roller assembly 256 (Fig.
11) .
. As illustrated in Fiq. 11, elongated roller asse~nbly 256 incluaes a drive sprocket 271 mounted on its axle 258 and a rack 272 engages the teeth of s~rocket 271. Rack 272 is reciprocated by cylinder 274 so as to drive elongated roller assembly 256.
The anale through which roller assembly 256 rotates 2S is adjustable and is controlled by a positionin~
screw 275 in the end of cylinder 274.
As illustrated in Figs. 11, 12 and 14, a ~?lurality of air nozzles 276 are mounted on exPansion clamPs 262, as by extending each nozzle 276 through the vertical le~ 26~ of the expansion clamps, so that the nozzles 276 are directed approximately parallel to the horizontal legs 264 of the expansion clamps.
Flexible conduits 278 connect each nozzle 276 to a source of air pressure.
When the cut segment of sheet material 34 ~7 _ has been moved by conveyor tapes 76h along the work table and by platform belt 246 along fold platform 241 a distance sufficient to move the entire cut seqment of sheet material entirely into fold expansion section 39, as determined by a photocell (not shown~ in the path of the sheet material, the movements of conveyor tape 76b on the work table-and of the platform belt 246 on fold platform 241 momentarily terminate tFiq. 10). Then cylinders 266 move expansion clamps 2~2 in a downward direction throu~h slots 255 in fold platform 241 until the horizontal legs 264 of the expansion clamps have urged the body portion of the segment of sheet material into enqagement with roller assembly 256 (Fig. 11). Immed~ately thereafter conveyor tape clamp 136b is raised away from conveyor taPe 76b on work table 72b and roller assembly 256 is rotated by its sprocket and rack 271, 272 ~Fiq. 11), moving its upper surface toward the fold in the sheet material.
The raising of conveyor ta~e clamp 136b frees the bodv portion of the sheet material, while the rotation of the roller assembly 25fi Provides a moving surface agalnst which the expansion clamp 262 has clamped the body portion of the sheet material.
Thus, the body portion of the segment 34 of sheet material is pulled toward the fold in the sheet material. In the meantime, air is moved through con~uits 278 leadinq to nozzles 276 carried by expansion clamps 262. This provides a flow of air directed beneath the fold platform 241 ~Fig. 11), into the hem. Thus f the portion of the sheet material pulled by the roller assembly 256 toward the fold in the sh~et material will he expanded by means of air Dressure~ resulting in an expansion of the hem previously formed bY folder 224.

1 1~99~0 After the'fold in the sheet material has been expanded in the manner illustrated in Fig. ll, hemming clamps 185 and 186 are ~oved downwardly toward engagement with the body portion of the cut se~ment of sheet material 34, to clamP the sheet material against hemmin~ belts 182 (Fiq. 12~ and immediately thereafter the expansion clamps 262 are raised away from roller assembly 256, upwardly through the slots 255 in fold platform 241. The now expanded fold 280 in the cut ed~e portion of the seqment of sheet material and the body portion of the seqment are moved by conveyor tape 182 and by platform belt 246 on toward hemming station 40.
Platform belt 246 is now moved at the same linear velocity as hemmin~ belt 182.
Hemmin~ Station As illustrated in Figs. 15 and 16, the segment of sheet material 3~ moves from the hem expansion section 39 on into the hemming section 40, by the 5egment moving out from beneath platform belt 246. Platform belt 246 is taken up by pulley 281.
Folding band 282 extends about pulley 283 which idles on the same shaft as pulley 281 and folding band 282 is moved down into engagement with the folded edge portion of the sheet material and cont~nues the movement of the sheet material alona fold platform 241. Fold platform 241 includes fold finger projection 284 that extends coextensively with the fold platform 241, and is formed by notch 285 in the fold Platform. OverlaPping fold finger 286 is suDported ~y bracket 288 from vertical support plate 242, and overlappinq fold finger 286 projects into the notch 285 an~ extends beneath fold fin~er projection 284. ~olding band 282 moves ~hrough notch 3s 285 and beneath overlaPpin~ fold fin~er 286 and moves 1179~

_ on through the sewinq machine 295 to compound pulley 300. In the meantime, stabilizin~ belt 290 is applied to the fold in the sheet material by its put-down sheave 291, runs off the end of fold finger projection 284, and is taken up by compound pulley 300. The fold finger projection 284, overlapping fol~ finger 286 and foldinq band 282 function to form the second fold in the cut edge portion of the sheet material, tuckinq the raw edqe of the sheet material beneath the large fold. Folding band 282 assures that the leading edqe of an oncoming seqment 34 of sheet material moves beneath overlapping fold f inqer 286, and overlappinq fold finger 286 tucks the raw ed~e beneath fold finqer projection 284.
When the segment of sheet material 34 emerges from the final folder, the now folded cut edge portion of the segment of sheet material moves into he~mer 24~. Hemmer 295 comprises sewing machine 296 and entrance and exit g~ide plates 304 and 318 positior.~d over guide belt 290 and folding band 282.
The gui~e plates each include downwardly facing slots such as slots 305 and 306 of auide plate 304 which conform to the shape of the band and belt, so as to gu~de and stablize the band and belt as they ap~roach and move away from sewinq machine 296. Leaf spring 308 holds entrance guide plate in its proper position and a~plies the proper tension thereto. Lower transport belt 309 moves upwardly through the work table from its pulley 310 and opening 311 and moves out from beneath fold platform 241 and then moves into its o~eninq 312 in the work table about pulley 314 beneath entrance 4uide plate 3~4.
As illustrated in Fiqs, 15 and 16, separator plate 301 is formed of thin sheet metal with smooth upper and lower surfaces and one end portion thereof 302 is attached in overlying I 1~99~0 - relationshi~ to the lower surface of fold Platform 241. The flexible seParator plate extends beyond the end of rigid fold platform 241 and continues the separation of the folded layers of the se~ment 34 of sheet material; howeYer, stabilizing belt 290 and folding band 282 apPly downward force sgainst the layers of the folded over edge portion 220 of the segment 34, the separator plate 301, the unfolded body portion 223 of the segment 34, the lower 1 transport belt 309 and the surface 72b of the work table, so that the lower transport belt controls the movement of the unfolded body portion 223 of the segment ad~acent the fold in the segment and the belt 290 controls the movement of the folded over edqe portion 220. Thus, the sheet material is accurately and po~itively transporte~ from fold platform 241 on throuqh sewinq machine 296.
Sewinq machine 296 is a single needle sewin~ machine, and its needle 315 is arranged to sew throuqh its presser foot 316 and between band 282 an~
belt 290, through the three la~ers of the hem formed in the sheet material. The exit ~uide plate 318 which is similar to entrance guide plate 304 also stabilizes and suides band 282 and belt 290 as they move away from sewing machine 296. ~Jhen the trailing edge of the segment of sheet material moves beyond sewing machine 296, the force applied by exit quide plate 31~ to ban~ and belt 282 and 290 keeps the trailing ed~e of the now sewn segment of sheet material from being snatched away from the sewing machine, causing the trailing edqe to be moved qradually away from the sewinq machine until it has emerqed from comDound pulley 300.
Drive ~ystem As illustrated in Fiq. 17, the drive system 1 179gl'~

_ for the conveyor tapes in the cutting section comprises motor 325 whicl~ drives throuoh sprockets 326 and 328 and chain 329 to rotate drive shaft 330.
The drive systems for each conveyor tape are similar and include drive sprockets 331 and 332 with their connec t i ng ch ain 334, shaft 335, sprockets 336 and 338 and their connectinq chain 339, 3nd conveyor tape 76a and 78a. Shaft 335 also extends throu~h conveyor tape 76a and 76b to gear 340 which is connec~ed through ~ears 341 and.342 to shaft 344 which drives conveyor ta~e 76~ and 78b, sprockets 345 and 346 and their connectin~ chains 348.
The hemmer drives are similar to each other and each includes a motor 349, drive pulleys 350 and 351 and their connecting belt 352, drive shaft 354, gear reducer 355, sprockets 355 and 358 and their connectin~ chain 359 and conveyor tape 182.
L~wer transport belt 309 which carries the lower surface of the segment 34 of sheet material from the fold platform to the needle of the sewing machine is driven by shaft 360 acting through sproc~ets 361 and 362 and belt 3~3 to drive phase shifter 364, and phase shifter 364 drives driven pulley 310 of transport belt 309. Air motor 365 2S controls phase shifter 364 throuqh its sprockets 366 and 367 and ccntrol chain 368. Valves 369 and 370 control air motor 365, to ca~se an increase or decrease from the output shaft of phase shifter 364, causin~ lower transport belt 309 momentarily to move faster than or slower than hemming belt 182, hemming guide band 301 and hemming stabilizing belt 302, to shif~ the lower transport belt 309 ahead or behind the he~ing belt 182, the hemmin~ guide band 301 and the hemminq stabilizing belt 3n2. Lower transport belt 309 therefore momentarily speeds up or slows ` I179~

_ down the movement of the body portion of the sheet material with respect to the folded over hem portion, so that the leading and trailing edges of the body and he~ portions are formed in overlying S relationshi~. ~ith this arrangement, the leading and trailin~ ed~es of the hems beinq formed by the sewing machines, such as sewin~ machine 296, can be controlled so that no ~dog ear" or protruding portion of the hem is permitted to be formed by the sewing machine.
Control Circuit As illustrated in Fi~s. 18a and 18b, three circuits are used to control the system. The first circuit is a 24 volt DC circuit, the second circuit is a 110 AC circuit and the third circuit is a 220 AC
circuit.
The 24 volt DC circuit comprises main conductors 371 and 372, with con~uctor 371 being the necative conductor and conducto~ 372 being the positive conductor. A pluralitv of switches appear in the circuit and are terme~ timing switches. These switches ar~ opened and closed by cams mounted on a rotatable c2m shaft (not shown)~ with the cam shaft bein~ driven by a timinq motor.
Main conductor 371 is connected to conductor 373 (Fig. 18~, which includes first stop switch 374, first start switch 375, accumulator switch 376 and the coil of first control relay CR1.
Also connected in parallel with start switch 375 is second start switch 378 and the second contact CRl-2 of the control relay CRl. Thus, the second contact CRl-2 forms a holding circuit throuqh the coil of the control relay.
The coil of control relay CRl in conductor 373 also closes the contact CRl-l into 110 AC circuit 1 1~9900 _ ~Fig. 18A~, makinq a circuit from main conductor 379, through conductors 380, 381, timin~ motor TM and main conductor 382. When timing motor TM begins its operation, i. immediately closes timing switch TSl, makina a circuit from main conductor 379 through conductor 384, timing switch T~1, conductor 381, timinq motor TM to main conductor 382. This causes timin~ motor TM to continue its operation. When considerin~ this function in connection with Fiq. 18, it will be seen that switches TSl and TS2 are first to close and last to oPen. Timing switch TS2 makes a ~ircuit from ~.ain conductor 371 through conductor 385 and then through main conductor 386. Thus, timing switch TS2 functions to energize a common conductor 386 to which most of the DC circuits are made.
Timinq switch TS3 is in a circuit from common line 3~6 through conductor 388 through manual switch 389, to pilot valve V3 which causes air motor 129 to move the qrip~in~ bar 105 from its home position to the entrance position of the cuttinq station 3~. In a~dition, in order to cushion the impact of the qrip~inq bar 105 as it moves into the entrance 83 of the cutting station, valve V is enerqized parallel with pilot valve V3 through conductor 290 to charge a plurality of dash pots (not sho~n) ~hich engaae the oncoming gripping har.
After grippin~ member 105 has reached the entrance of the cutting station 32, the cam system closes timer switch TS4 which makes ~ circuit from common line 386 through conductor 391, manual switch 392, and oilot valve V5 to main conductor 371. This causes the aripoing bar to move its upper clamp member down against the lower clam~ member 11~ and to ~rip the ~eadin~ edqe portion 21c of the sheet material 21~

I. 1799~0 _ After the qrippinq bar is in gripping relationshi~ with the leadin~ edge portion of the sheet material, the clamp assembly 81 is moved up.
This is accomplished b~ a cam on the cam shaft 5 . closin~ timer switch TS5 which makes a circuit from common 386 through conduct 394, through manual switch 395, throuqh pilot valve V8 to main conductor 372.
As soon as the clamp assembly is up to release the leading edge portion of the sheet material, the qrippina bar is moved from the entrance position at the cutting station back to its home position to pull the ~heet on into the cutting station 32. This is accomplished by closing timer switch TS6 which makes a circuit from common 386 throu~h conductor 394, manual switch 395 through pilot valve V4 to main conductor 372. Also, a circuit is made through conductor 3g6 to dash pots ~not shown) throu~h valve V. The dash pots cushion the impact of the oncoming grippinq bar 105.
After the sheet material has been pulled into the cutting station by the gripping bar, the slack must be formed in the segment of sheet material by movinq the slack bar 145 down into the sheet material. This is accomplished by a cam closing timer switch TS15 which makes a circuit from common 386 through conductor 428 to pilot valve V14 to main conductor 372.
After the gripping member reaches its home position and slack has been formed in the sheet, the clamp assembly 81 is again moved into clamping re-lationship with the sheet material to hold the sheet material stable for the subsequent cutting step. This is accomplished by a cam closing timer switch TS7 which makes a circuit from common 386 through conductor ~98, manual switch 399 an~ pilot l 179900 - valve V7 to main conductor 372.
The first pair of convey~r taPe bars 136 and 138 are ~oved down into enqaqement with the sheet materia~ toward their respective conveyor tapes 76 and 78 at the same time the clamp assembly is moved down to cla~p the sheet material. This is accomplished by a cam closina the timer switch TS8 which makes a circuit from common 386 through 0 conductor 400, manual switch 401, thro~gh ~ilot valve V9 to main conductor 372. Pilot v~lve v9 causes the pneumatic cylin~ers 139 and 141 of the clamp bars to move the clamp bars do~n into engaqement with the sheet material.
~ow that the conveyor tape clamp bars, the clamp assembly an~ the qripping bars have all qrasped the segment of sheet material extending through the cuttinq sect~on 32, the disc cutter is actuated to cut across the sheet material. This is accomplished by a cam closinq the timer switch TS9 which makes.a circuit from co~mon 386 through conductor 402, manual switch 404, and steppinq switch 405 throuqh either of conductors 406 or 408 to pilot valves Vl or V2 and to dash ~ot valves V which are in parallel with the pilot valves Vl and V2. Also, a parallel circuit is made thro~qh conductor 409 throuqh the coil of steppin~ relay CR3 and throuah the coil of the blade run relay CRS. The contacts 405 of steppinq relay CR3 move alternately to chan~e conductor 406 or 408, to move the knifè in one direction and then in the other direction. Also, control relay CR2 in the 24 volt circuit closes its contact CR2-1 in the 110 AC
circuit, makinq a circuit from conductor 379 through cond.uctor 410 to control relay CR4 to con~uctor 382.
Control relav CR4 closes its contacts CR4-1 in the 220 AC circuit, or closes its contact CR4-2, causing ~ 1799~0 _ the cutter disc motor 172 to reverse and begin operation.
As the cutter disc is making its cut throuqh the ~heet material, the gripping bar 105 releases the leadinq edqe of the sheet material.
This is accomplished by closina timer switch TS10 which makes a circuit from common 386 throu~h conductor 412, through manual switch 414 to Pilot valve V6 and main conductor 372.
After the cut in the sheet material has been completed and the grippin~ bar is opened, the first pair of conveyo~ tapes beqin their movements to move the sheet material in a direction extending along the cut edges thereof to the transverse station. ~his is accomplished by closing timer switch TSll which makes a circuit from common 386 through conductor 41S, manual switch 416, throuqh a photocell circuit 418, to pilot valve Y13 to main conductor 372. Pilot valve V13 actuates motor 325 and motor 325 continues to run until the photocell P
in photocell circuit 418 sees the oncomin~ edge of the sheet material, where u~on th e circuit to p i lot valve V13 is opened, thereby causing the sheet to stop.
When the cut segment of sheet material is movinq from the cutting station 32 to the transfer station 39, the second convevor tape clamp bars 136 and 138 must be raised momentarily in order to avoid retardinq the movement of the oncoming edge of the cut se~ment of sheet material. This is accomplished by closinq timer switch TS12 which makes a circuit from common 386 through conduct 420, manual switch 421 to pilot valve V12 to main conductor 372.
Immediately thereafter, the conveyor tape clamD bars 136 and 138 must be lowered again. This is l ~ 79900 accomplished by closing timer switch TS13 which makes a circuit from common 386 through conductor 422, manual switch 424 through pilot valve Vll to main conductor 372.

After the sheet material has left the cutting station 31, the conveyor tape clamp bars 136a and 138a must be raised out of the way of the gripping member 105 so that the gripping bar can move back from its home position to che entrance position of the cutting station 32. This is accomplished by closing timer switch TS14 which makes a circuit from common 386 through conductor 425 through manual switch 426 through pilot valve V10 to main conductor 372.

When a flaw appears in the sheet material the cut segment in which the flaw appeared is to be marked to identify that segment as having a flaw. The sheet inspection and marking system of the type disclosed in U.S. patent 4,204,012 is used to make the mark on the segment. In order to detect that the last portion of the segment of sheet material to be cut is moving into the cutting station, timer switch TS16 is closed and makes a circuit to the marking system (not shown).

The various manual switches identified throughout the circuit of Flgs. 18A and 18B permit the operator to temporarily close a circuit to the various functional elements of the system.
For example, when it is desired to raise or lower the clamp assembly 81, the manual switch 399 or 395 can be moved from its normally closed position with its conductor 398 or 394 to a parallel conductor 399a or 395a to make a circuit to main conductor 371.

The timing of the movements that are controlled by the circuitry illustrated in Figs. 18A

_ and 18B are illustrated ~raPhically in Fig. 18.
As illustrated in Fig. 20, the phase shifting of lower transport belt 309 (Fiq. 15~ is controlled by a circuit 430. Photocells 431 and 432 are positioned in al ignment with the path of the seqments 34 of sheet material moving through the sewina machines 296. Photocell 431 in the upper DortiOn of the circuitry detects the trailing edge of a s~ament ~assing to the sewing machine while photocell 432 in the lower portion of the figure detects the oncominq edce of the seq~ent. The uPper and lower Portions of the control circuit of Fig. 19 are substantially the same, in that each includes a common line 434, conductor 435 leading from common to the photocell 431 or 432, an on/off switch 436, resistor 438 and transistor 439. Transistor 439 emits a signal in response to a change in the signal from the photocell 431, and the signal is transmitted through diode 440 in parallel to capacitor 441 and resistor 442 to pulse relay 444. The variable resistance 445 is also connected to transistor 439 through resistance 446 and conductor 448. Thus, variable resistor 445 controls the duration of the pulse signal received from capacitor 441 to pulse rela~ 444.
When relay 444 is pulsed to its closed condition, a siqnal is received from conductor 449 through the closed switch 450 of relay 444, through conductor 451, resistance 452 and variable resistance 454, resistance .455 to transistor 456. Capacitor 458 is connected in parallel through conductor 459 with respect to transistor 45fi. When transistor 456 is pulsed, it emits a siqnal to conductor 460, and in parallel through diode 451 and air motor valve 369 (Fig. 16). Air motor valve 369 permits the passage l 1799~0 _ - of air under pressure throu~h a con~it to air motor 365, ca~sin~ a rotation of the corrector sha~t 366, 367 of Dhase shifter 364. This causes a shift in the phase of the lower trans~ort belt 309, causin~ a temporary slowdown of the belt. This causes the main body portion 223 of the sheet adjacent the folded over hem 220 to move slower as the trailinq ed~e of the cut segment of sheet material moves throuqh the sewing machine. Therefore, the folded over hem will not be Permitted to han~ out in its finally sewn toqether conflguration and the selvages of the seqment 34 will be ali~ned.
Photocell 431 which detects the oncoming trailing edqe of the seqment of sheet material is the type of photocell that detects li~ht, while Photocell 432 which detects the oncomin~ lea~ing ed~e of the seqment of sheet ~aterial is the type that detects dark. Thus, an extra transistor 465 is placed in the ~lower portion of the circuit of Fiq. 19 to invert the siqnal from photocell 432. The remaininq portion of the lower circuit is substantially identical to the upper portion. The air motor valve 370 therefore functions to control air motor 365, thus creating an input to the corrector shaft of the phase shifter 364, resultin~ in a change in speed of the lower transport belt 309 as it carries the lower main body portion of the seqment of sheet material on into the sewin~ machine. It will be noted that there are two variable res~stors 445 and 454 in both the upper and lower portions of the circuitry. Yariable resistance 454 is ~sed to fine tune the phase shifter while variable resistance 445 is used to ~ultiply the effect of the siqnal received by air ~otor valve 369 or 37~.
While this invention has been described in ~ 17991)0 _ detail with particular reference to an embodiment which is specifically constructed to form bed sheets, wherein a hem expander is used to form the large hem at the head of a bed sheet, it will be understood S that other sheet products can be fabricated with the disclosed system and hem ex~anders can be employed on both edges of the sheet material, if desired.
Moreover, it will be understood that variations and modificat~ons of the disclosed embodiment can be effected within the spirit and scope of the invention as described hereinbefore and as defined in the appended claims.

Claims

WHAT IS CLAIMED IS:

1. A method of forming a hem in sheet material comprising the steps of folding an edge portion of the sheet material into overlying relationship with the body of the sheet material, holding the edge portion from movement in a direction across its length, positively moving the body of the sheet material toward the fold in the sheet material, directing a flow of fluid toward the fold between the layer of the folded edge portion and the layer of the body of the sheet material to expand the folded portion of the sheet material, and sewing through the folded portion and the body portion of the sheet material to form a hem.

2. The method of Claim 1 and wherein the step of folding an edge portion of the sheet material comprises moving the sheet material in a direction parallel to its edge and progressively folding the edge portion thereof about the edge of a platform to locate the edge portion of the sheet material on one side of the platform and the body of the sheet material on the other side of the platform, and wherein the step of holding edge portion from movement across its length comprises applying a flight of a conveyor belt member to the folded edge portion to bias the folded edge portion toward engagement with the platform, and wherein the step of positively moving the body of the sheet material toward the fold comprises urging the body of sheet material against a surface and moving the surface in the direction of the fold in the sheet material, and wherein the step of directing a flow of fluid toward the fold comprises directing a flow of fluid between the platform and the body of the sheet material.

3. The method of Claim 1 and wherein the step of folding an edge portion of the sheet material into overlying relationship with the body of the sheet material comprises moving the sheet material along its length on a work surface in a direction approximately parallel to the edge of the sheet material, progressively folding the edge portion of the sheet material upwardly and to an overlying relationship with the body of the sheet material and moving the edge portion of the sheet material along a platform spaced above the work surface.

4. the method of Claim 3 and wherein the step of holding the edge portion of the sheet material from movement in a direction across its length comprises applying a flight of an endless conveyor belt to the edge portion of material and moving the flight of the conveyor belt in a direction parallel to the edge of the sheet material.

5. The method of Claim 1 and wherein the step of positively moving the body of the sheet material toward the fold in the sheet material comprises urging a portion of the body of the sheet material into engagement with a movable surface and moving the movable surface toward the fold in the sheet material.

6. The method of Claim 5 and wherein the step of urging a portion of the body of the sheet material into engagement with a movable surface comprises applying a plurality of elongated aligned clamp bars downwardly into the body of the sheet material until the sheet material is pressed into contact with the upper surface of an elongated roller rotatable about an axis parallel to the clamp bars and to the fold in the sheet material, and rotating the roller about its axis with the surface thereof adjacent the clamp bars moving in a direction from the clamp bars toward the fold in the sheet material.

7. A method of forming a hem in sheet material comprising the steps of moving the sheet material on a work surface in a direction parallel to its edge, folding the edge portion of the sheet material upwardly over a platform spaced above the work surface as the sheet material moves on the work surface, holding the edge portion of the sheet material against the platform, moving the body of the sheet material toward the fold in the sheet material, directing a flow of air beneath the platform toward the fold in the sheet material to expand the folded portion of the sheet material, moving the edge portion of the sheet material off the platform and into folded overlying abutment with the body portion of the sheet material, and sewing through the edge portion to the body portion.

8. The method of Claim 7 and wherein the step of directing a flow of air beneath the platform toward the fold comprises directing a flow of air between the platform and the body of the sheet material into the fold in the sheet material.

9. The method of Claim 7 and wherein the step of moving the body of the sheet material toward the fold in the sheet material comprises moving a plurality of elongated aligned clamp bars downwardly to a level below the platform into the body of the sheet material and toward engagement with the upper surface of an elongated roller means extending parallel to and beneath the clamp bars, and while the clamp bars are moved toward engagement with the upper surface of the roller means, rotating the roller means in a direction that moves its upper surface toward the fold in the sheet material to pull the body of the sheet material toward the fold in the sheet material, and wherein the step of directing a flow of air between the platform and the body of the sheet material comprises directing the flow of air while the clamp bars are moved toward engagement with the upper surface of the roller means and while the roller means rotates.

10. The method of Claim 7 and wherein the steps of moving the sheet material parallel to its edge and folding the sheet material are completed prior to the steps of moving the body of the sheet material toward the fold and directing a flow of air toward the fold.

11. A method of forming a hem in the edge of a segment of sheet material comprising moving the segment along a path with the edge portion to be hemmed extending along the path, folding the edge portion upwardly into overlying relationship with the body portion of the segment, simultaneously moving the folded over portion with an upper belt member toward a sewing machine and moving the body portion of the segment beneath the folded over portion with a lower belt member toward the sewing machine, and in response to detection of an on-coming edge of the segment approaching the sewing machine shifting the phase of one of the belt members to change the position of the on-coming edge of the body portion of the segment beneath the folded over portion with the on-coming edge of the folded over portion, and sewing through the overlying folded over portion and the body portion of the segment beneath the folded over portion.

12. The method of Claim 11 and wherein the step of folding the edge portion to be hemmed comprises folding the edge portion to be hemmed upwardly onto a platform spaced over the body portion of the segment, and where in the step of simultaneously moving the folded over portion and the body portion of the segment comprises engaging and moving the body portion from a position beneath the platform to a position beyond the end of the platform and engaging and moving the folded over portion from a position on the platform to a position beyond the end of the platform.

13. A method of forming a hem in a segment of sheet material comprising the steps of moving the segment of sheet material along a path in a direction parallel to its edge, folding the edge portion of the segment of sheet material upwardly over a platform positioned over the segment of sheet material as the sheet material moves along the path, engaging and moving the folded over edge portion of the sheet material along the platform with an upper conveyor means positioned over the platform, engaging and moving the unfolded portion of the segment of the sheet material adjacent the fold in the segment along the platform with a lower conveyor means positioned beneath the platform, detecting the leading edge of the segment of sheet material as the sheet material moves along the path, and in response to the detection, changing the speed of operation of one of said conveyor means with respect to the other of said conveyor means to change the position of the leading edge of the unfolded portion of the segment with respect to the position of the leading edge of the folded portion of the segment, moving the unfolded portion of the segment and the folded portion of the segment off the platform, and sewing through the unfolded Portion and folded portion of the segment.

14. The method of Claim 13 and further including the step of increasing the width of the folded edge portion of the segment of sheet material after the segment has been folded and prior to the step of changing the velocity of one of the conveyor means.

15. The method of Claim 13 and further including the step of directing a flow of air into the fold of the sheet material to expand the width of the folded over portion of the segment of sheet material.

16. In apparatus for hemming sheet material wherein a segment of sheet material is moved on a work surface along a path in a direction parallel to an edge of the sheet material which is to be folded and sewn into a hem, the improvement therein of a fold platform mounted in spaced parallel relationship with respect to said work surface over the path of the segment of sheet material and including an edge portion extending along the path of the segment of sheet material, folding means for folding the edge portion of the segment of sheet material upwardly from beneath the fold platform about the edge portion of said fold platform and onto the top surface of said fold platform in overlying relationship with respect to the body portion of the segment of sheet material, means movable downwardly against the edge portion of the segment of sheet material on the top surface of said fold platform for moving the edge portion along the fold platform and for holding the edge portion from movement in a direction across its edge, a movable surface adjacent said fold platform and positioned vertically with respect to the path of the segment of sheet material, clamp means for clamping the body portion of the segment of sheet material against said movable surface, means for moving said movable surface toward the fold in the segment of sheet material, and means for directing a flow of fluid from beneath said fold platform toward the fold in the segment of sheet material to expand the folded portion of the segment of sheet material.

17. The apparatus of Claim 16 and wherein said movable surface comprises an elongated roller positioned beneath said fold platform and the Path of the segment of sheet material and rotatable about an axis parallel to the edge portion of said fold platform, and wherein said clamp means comprises at least one clamp member movable from above the path of the segment of sheet material downwardly toward engagement with the upper surface of said roller to bias the body portion of the segment of sheet material against said roller.

18. Apparatus for forming a hem in the edge of a segment of sheet material comprising means for moving the segment along a path with the edge portion to be hemmed extending along the path, a fold platform extending along the path and spaced over the path, means for folding the edge portion upwardly from the path onto the top surface of said fold platform in overlying relationship with respect to the body portion of the segment, upper belt means for engaging and moving the folded over portion of the segment at a position on said platform to a position beyond the end of said platform, and lower belt means for engaging and moving the body portion of the segment from beneath said platform to a position beyond the end of said platform, detecting means for detecting the on-coming edge of the segment, and phase shifting means responsive to said detecting means for shifting the phase of one of said belt means to momentarily change the velocity of said one of said belt means with respect to the other of said belt means.