US2751222A - Sheet-folding machine - Google Patents

Description

June 19, 1956 R. G. DEXTER SHEET-FOLDING MACHINE 8 Sheets-Sheet 1 Filed June 19, 1952 IN VEN TOR.

June 19, 1956 R. G. DEXTER SHEET-FOLDING MACHINE 8 Sheets-Sheet 2 Filed June 19, 1952 HVVENTUR. F Aek'f' ('7- DCGEI- June 19, 1956 R. G. DEXTER SHEET-FOLDING MACHINE 8 Sheets-Sheet 3 Filed June 19, 1952 June 19, 1956 R. e. DEXTER 2,751,222 SHEET-FOLDING MACHINE j. -9+-L chum.

attorneg June 19, 1956 R. G. DEXTER SHEET-FOLDING MACHINE 8 Sheets-Sheet 5 Filed June 19, 1952 INVENTOR. 706414 6. D4 0%,.

June 19, 1956 DEXTER 2,751,222

SHEET-FOLDING MACHINE Filed June 19, 1952 8 Sheets-Sheet 6 INVENTOR. ROIe -f E 1 June 19, 1956 R. G. DEXTER SHEET-FOLDING MACHINE 8 Sheets-Sheet 7 Filed June 19, 1952 INVENTOR.

June 19, 1956 R. G. DEXTER SHEET-FOLDING MACHINE 8 Sheets-Sheet 8 Filed June 19, 1952 United States Patent SHEET-FOLDING MACHINE Robert G. Dexter, Lexington, Mass., assignor, by mesne assignments, to Barkley & Dexter, Incorporated, Fitchburg, Mass., a corporation of Massachusetts Application June 19, 1952, Serial No. 294,307

8 Claims. (Cl. 27081) This invention relates to a sheet-folding machine.

In general the object of the invention is to provide a novel, efficient and superior sheet-folding machine, adapted for use in automatically folding sheets, such as towels and the like, in an accurate, rapid and practical manner.

Another object of the invention is to provide a folding machine of the character specified wherein provision is made for forming one or more parallel folds in the sheet and for thereafter forming one or more folds at right angles to the first folds in a novel and superior manner.

With these general objects in view, and such others as may hereinafter appear, the invention consists in the sheetfolding machine and in the various structures, arrangements and combinations of parts hereinafter described and particularly defined in the claims at the end of this specification.

In the drawings illustrating the preferred embodiment of the invention, Figs. 1 and 1A taken together comprise a view in side elevation of the present sheet-folding ma chine; Fig. 2 is an end view of the machine as seen from the left of Fig. 1A, some of the parts being broken away to more clearly illustrate the transfer mechanism; Figs. 3, 4, 5 and 6 are perspective views illustrating the sequence of the folding operations performed on the present machine; Fig. 7 is a plan view of the transfer mechanism; Fig. 8 is a side elevation of the same showing the transfer mechanism in its upwardly rocked position; Figs. 9 and 10 are views in front and side elevations respectively of the tucking mechanism; Fig. 11 is a detail view in side elevation of the folding or tucking arm; Fig. 12 is a detail view I in side elevation of a portion of the transfer mechanism; j Fig. 13 is a cross-sectional view taken on the line 1313 ,..of Fig. 12 illustrating connecting elements for the transfer mechanism; Figs. 14 and 15 are cross-sectional views similar to Fig. 13 showing the transfer elements in different positions of operation; Fig. 16 is a detail view of brake mechanism associated with the transfer mechanism; Fig.

117 is a side elevation of a differential timing unit forming :a part of the control mechanism, some of the parts being :shown in cross section; Fig. 18 is a cross-sectional view taken on the line 18-18 of Fig. 17; Figs. 19, 20, 21 and 22 are diagrammatic views of a folding station and illus- Irating a sheet in different positions of advancement relative to the control mechanism for effecting folding of the sheet; Fig. 23 is a detail view of the timing mechanism shown in a different position of operation; and Fig. 24 is a wiring diagram of the control mechanism embodied in the present sheet-folding machine.

In general the present invention contemplates a sheetfolding machine having a plurality of successive folding mechanisms for forming successive folds in the sheet and wherein each folding mechanism is arranged to be automatically operated through control means including a photo-sensitive detector arranged to detect the passage of the leading and trailing edges of the sheet during its advance into folding position; and a differential timing mechanism responsive to the detecting means and arranged to actuate the folding mechanism when the sheet has been advanced through a predetermined and selected distance relative to the folding mechanism whereby the sheet may be accurately folded in one-half, one-third or other selected proportion of its length irrespective of the length or variations in the length of the sheet.

in the illustrated embodiment of the invention the distance between the photo-sensitive detector and the folding member is fixed, and in operation, when the leading edge of the sheet trips the photo-sensitive element, the timing mechanism is caused to rotate at one rate of speed relative to the advance of the sheet, and when the trailing edge of the sheet passes the detector, the timing mechanism is caused to rotate at another rate of speed relative to the advance of the sheet, the total rotation of the timing mechanism being fixed and related to the fixed distance between the detector and the folding member. As a resuit, the timing mechanism effects actuation of the folding member at a predetermined and selected point proportionate to the length of the sheet, such proportion being maintained irrespective of the length of the sheet. For example, when the sheet is to be folded in half, the timing mechanism is caused to rotate at one-half speed relative to the advance of the sheet so that when the sheet has traveled its full length relative to the detector, the timing mechanism has rotated through a proportionate distance equal to one-half the length of the sheet. At this time, the centerline or fold line of the sheet is disposed one-half length beyond the detector. When the trailing edge of the sheet passes the detector, the timing mechanism is caused to rotate at full speed relative to the advance of the sheet, and since the remaining travel of the sheet to dispose the centerline thereof in alignment with thefolding member is related to the remaining rotation of the timing mechanism to effect operation of the folding member, the latter will be operated to fold the sheet in half. The sheets may be similarly folded in one-quarter or one-third by merely changing the initial speed of the timer to rotate one-quarter speed or one-third speed respectively relative to the advance of the sheet as will be hereinafter more fully described.

The present sheet-folding machine may and preferably will comprise a lower folding section arranged to form one or more parallel folds, and an upper folding section arranged at right angles to the lower folding section, and novel transfer means is provided for transferring the sheet from the lower section to the upper section, the transfer operation forming a fold at right angles to the first section. Succeeding folds may be made during the progress of the sheet through the upper folding section whereupon the completely folded sheet may be delivered from the machine.

Referring now to the drawings, in general the present sheet-folding machine includes a plurality of receiving belts 10 upon which a sheet to be folded is place to be advanced into operative position to a first folding station, indicated generally at 12, arranged to automatically fold the sheet intermediate its length as determined by the advance of the sheet past photo-sensitive detecting means 14 forming a part of the control mechanism to be described. The once-folded sheet is then advanced past a second photo-sensitive detector 16 and into operative relation to a second folding station, indicated generally at 18, arranged to automatically form a second fold parallel to the first fold at an intermediate point in accordance with the operation of the control mechanism associated with the photo-sensitive detector 16. The twicefolded sheet is then advanced along conveyor belts 20 into operative relation to a transfer and third folding station, indicated generallyat 22. During its advance to the transfer station 22, the twice-folded sheet passes a third photo-sensitive detector 24 forming part of control mechanism for actuating the transfer mechanism to deliver the sheet into an upper folding unit, indicated generally at 26, and disposed transversely to the lower or initial folding unit, the transferring operation forming a third fold at right angles to the previously formed folds. The sheet is then advanced past a fourth photo-sensitive detector 28 and into operative relation to a fourth folding station, indicated generally at 30, arranged to form a final fold parallel to the third fold whereupon the completely folded sheet is delivered out of the machine on conveyor belts 32.

As herein shown, the receiving conveyer comprises a series of transversely spaced and relatively narrow parallel belts arranged to run the full length of the machine over an idler roller 34 disposed at the receiving end of the machine, as shown in Fig. 1, and a driving roller 36 disposed at the other end of the machine, as shown in Fig. 1A. The idler roller 34 may be journalled in belt-tightener bearings 38 adjustably supported in guides 40 formed in the machine frame. As shown in Figs. 1A and 2, the driving roller 36 is arranged to be continuously driven through connections including a motor 42, variable drive mechanism 44, gear-reduction unit 46 and sprocket and chain drive 48 connected to the drive shaft 50.

The upper run of the receiving conveyor 10 may pass over a supporting table 52, as shown in Fig. l, and the sheet to be folded may be placed on the conveyer with one edge thereof in alignment with an adjustable guide member 54 for aligning the sheet in predetermined relation to the transfer mechanism for performing the third fold, as will be described.

As illustrated in Fig. l, the first told is performed by a tucking or folding arm 56 fast on a rocker shaft 58 journalled in suitable bearings in the machine frame. As illustrated in detail in Fig. 11, the tucking arm 56 is provided with a plurality of spaced fingers 60 arranged to extend between the belts 10 when the arm is rocked upwardly to engage and lift a medial portion of the sheet into the bight of cooperating belt conveyers 62, 20 running over spaced rollers supported above the receiving conveyer 10, each conveyer 62, 29 likewise comprising a series of spaced parallel belts. As herein shown, the belt conveyer 62 is arranged to run over a driving roller 66 and an idler roller 68 suitably journalled in the machine frame. The cooperating conveyer 20 is arranged to run under idler roller 69, over roller 66 with the belts in cooperating engagement with the belts 62, and around roller 70, the upper run of the belts 20 extending to the end of the machine, as shown in Fig. 1A, and passing around roller 72 and belt-tightener rollers 74, 76 back to the idler roller 69. Suitable belt guides, indicated at 78, may be provided to maintain the belts in predetermined spaced relation, each guide comprising a transversely extended angle bar provided with a plurality of upstanding curved spacers 80 extended between the belts, as shown. The end roller 72 may also be provided with a plurality of spaced collars 73 defining grooves in which the belts 20 are guided.

In the illustrated embodiment of the invention, the first fold is formed along a medial line to fold the sheet in half, as shown in Fig. 3, the folded sheet being supported and advanced between the continuously driven belts 62, 20 until it arrives in operative relation to the second folding station 18. The second fold is performed by a tucking or folding arm 82 similar in construction and mode of operation to the first folding: arm 56. In operation the arm 82 is rocked upwardly to engage and lift the once-folded sheet along a medial line into the bight of cooperating belts 20 and 84 running over spaced rollers disposed above the conveyer 62 to again fold the sheet in half, as shown in Fig. 4. The belts 20 pass around roller 70, as described, and the belts 84 are arranged to run over idler roller 36 and driving roller 88, the lower run of the belts 84 cooperating with the upper run of the belts 20 to advance the folded sheet therebetween, as illustrated. It will be understood that the above-described first and second folds are automatically effected through control mechanism to be described to cause operation of their respective folding arms 56, 82 at predetermined points with relation to the length of the sheet in accordance with timing mechanism actuated by the detection of the leading and trailing edges of the sheet as it passes the photo- sensitive devices 14, 16 respectively.

The twice-folded sheet is then advanced on the belt conveyer 20 past the photo-sensitive detector 24 and into operative relation to the transfer mechanism 22. As herein shown, the transfer mechanism 22 comprises a parallel linkage including parallel arms 90, 92 and link 94 arranged longitudinally of the belt conveyor 20. The transfer linkage is normally disposed in a lowered position, as shown in Fig. 1A, and when actuated by the passage of the leading edge of the twice-folded sheet past the photo-sensitive detector 24, the transfer linkage is rocked upwardly between adjacent belts 20 to engage an intermediate portion laterally of the sheet, and to insert the same into the bight of cooperating belts 96, 32 running over spaced rollers to form the third fold at right angles to the first two folds, as shown in Pig. 5.

It will be observed that the line of the third fold may be predetermined by initial placement of the sheet at the receiving end of the conveyer 19, one edge of the sheet being aligned with the guide member 54, see Fig. 2, the latter being adjustable relative to the centerline of the longitudinally extended transfer linkage 22 to produce a fold in the desired predetermined position.

In practice the transfer linkage 22 is rocked upwardly and rearwardly opposite to the direction of travel of the belts 20, and in order to avoid carrying the sheet rearwardly during the transfer operation and to provide a substantially vertical transfer movement, a compensating parallel linkage is provided comprising parallel arms 10% pivotally connected to the transfer link 94 and connecting link 162. The connecting link 102 is connected at one end by a link 104 to a bracket 106 attached to the machine frame so that in operation when the transfer arms 90, 92 are rocked clockwise viewing Fig. 8, the compensating arms are caused to rock counterclockwise, thus counteracting the tendency of the transfer unit 22 to carry the sheet rearwardly during the transfer operation.

Furthermore, in order to prevent the laterally extended ends of the folded sheet from being pulled forwardly on the continuously moving belts 20 during the transfer operation, a plurality of relatively shorter parallel linkages, comprising elevating linkages 107, 109, disposed on both sides of the transfer linkage, are arranged to be rocked from a position below the belts 20 to a position slightly above the belts, the shorter linkages operating simultaneously with the transfer linkage to form an elevated support for the lateral ends of the sheet during the transfer operation. As shown in Figs. 2, 7 and 8, each elevating linkage includes parallel arms 108 and connecting link 110, and in practice, the transfer linkage is immediately returned to its lowered position while the supporting linkages are permitted to remain in their upwardly rocked position until the trailing edge of one side of the sheet passes beyond the photo-sensitive detector 24 and into the upper folding unit 26 whereupon the supporting linkages are returned to their lowered position, as will be described.

As illustrated in Fig. 2, the cooperating belts 96, 32 between which the twice-folded sheet is inserted to form the third fold forms a part of the upper folding unit 26, such belts also comprising a plurality of relatively narrow spaced belts running over adjacent rollers and cooperating to support and advance the folded sheet therebetween.

As herein shown, the conveyer belts 9.6 are arranged to run over roller 112, idler roller 114, and driving roller 116, and the cooperating conveyer belts 32 are arranged to run under roller 118, over the adjacent roller 112 and around a driving roller 120 disposed to present the lower run of the belts 32 in cooperative engagement with the upper run of the belts 96, as shown. The upper run of the conveyer belts 32 comprising the delivery conveyer extends over an idler roller 122 and back to the roller 118.

The sheet being advanced between the belts 96, 32 is carried past the photo-sensitive detector 28 and into operative relation to the fourth folding station 30 which may comprise a tucking or folding arm 124 similar in construction and mode of operation to the first folding arm 56. In operation the folding arm 124 is rocked upwardly to extend the fingers 126 between the spaced belts 96 and to insert the sheet into the bight of cooperating belts 32 and 128, the fold being preferably made to dispose the extended portion of the sheet under the third folded portion, as illustrated in Fig. 6. The belts 128 are arranged to run around a driving roller 130 disposed adjacent the roller 120 and around an idler roller 132 disposed to present the lower run of the belts 128 in cooperating engagement with the upper run of the belts 32. The completely folded sheet carried along between the belts 32, 128 is then delivered out of the machine on the conveyer belts 32.

Referring now to Figs. 1 and 1A, the first and second folding units 12, 18 are arranged to be operated by similar tucker operating units indicated generally at 134, 136 respectively, and the transfer mechanism 22 is likewise arranged to be operated by a similar operating unit 138, and such operating units as well as the various belts and rollers comprising the lower folding section for forming the first two folds and the transfer operation are arranged to be continuously driven by one endless chain 140 arranged to run around a driving sprocket 142 fast on the drive shaft 50. It will be observed that the drive roller 36 for the receiving conveyer belts is mounted on the shaft 50, and starting at the left-hand end of Fig. 1A and following the upper run, the driving chain 140 extends from the drive sprocket 142 to a sprocket 144 driving the transfer operating unit 138; then under a. sprocket 146 driving the roller 66 for the belts 62; over sprocket 148 driving the roller 88 for the belts 84; around idler sprocket 150; around sprocket 152 secured to the roller 70 for the belts over sprocket 154 driving the second fold operating unit 136; under and over idler sprockets 156, 158 respectively; under sprocket 160 driving the first fold operating unit 134; over idler sprocket 162 and then back to the driving sprocket 142.

The upper folding unit 26 is likewise driven through connections from the main driving shaft 50 as illustrated in Figs. 1A and 2 wherein the shaft 50 is connected by a chain and sprocket drive 164 to a shaft 166 upon which the roller 72 is mounted, and a second chain and sprocket drive 168 connects the shaft 166 to a shaft 170. The driven sprocket 172 is loose on the shaft 170 and forms the driving member of a manually engageable clutch, the driven member 174 being keyed to the shaft and manually slidable into and out of operative engagement for the purpose of rendering the upper unit inoperative when only two folds are desired in the sheet. The shaft 170 is connected by bevel gears 176, 178 to a cross shaft 18!) upon which the roller 130 for the belts 128 is mounted. The driving roller 120 for the belts 32 is driven from the cross shaft 180 by spur gears 182; the driving roller 116 for the belts 96 is driven from the shaft 180 by a chain 184 running over sprockets 186, 188 and idler sprockets 190, 192; and the tucker operating unit indicated at 194 for operating the fourth folding mechanism 30 may be connected to the shaft 170 by a chain and sprocket drive 196.

From the description thus far it will be observed that the machine is continuously driven and that in operation fast on the tucker arm shaft.

.detecting means,

a sheet placed on the receiving conveyer 10 is continuously advanced through the machine and automatically folded at successive stations to form a completely folded sheet which is delivered from the machine on the delivery conveyer 32. In accordance with the present invention, each tucker operating unit is arranged to be selectively and automatically operated to effect folding of its sheet at a predetermined and selected point relative to its length by control mechanism including the photo-sensitive detecting means actuated by the passage of the leading and trailing edges of the sheet to operate a dilferential timing mechanism, one of which is indicated generally at 198 and which is connected to electro-responsive means arranged to operate its respective folding mechanism.

As illustrated in Figs. 9 and 10, each tucker operating mechanism is similar in construction and mode of operation so that a description of one unit will sufiice for all. As herein shown, each tucker operating unit includes a one-revolution clutch, indicated generally at 200, operatively connected to a shaft 202 journalled in suitable bearings 204, 206 attached to a side frame 208 and to an outboard bracket 210 extended from the side frame respectively. A earn 212 fast on the shaft 202 is arranged to cooperate with a roller 214 carried by an arm 216 Thus, in operation when the one-revolution clutch 200 is operatively engaged, the cam 212 will make one revolution to rock its tucking arm upwardly to perform the folding operation, the cam causing the arm to be immediately returned to its lowered position. The one-revolution clutch 200 may be of any usual or preferred design having a driving element 218 loosely mounted on the shaft 202 and formed integrally with the drive sprocket over which the drive chain runs. The driven element 220 of the clutch may be keyed to the shaft 202 and is arranged to cooperate with a solenoid operated latch bar 222 pivotally mounted at 224 and having a. shouldered portion 226 arranged to engage: a cutout portion 228 of the clutch to disengage the same.

The latch bar 222 is urged in a counterclockwise direction viewing Fig. 9 by a spring 230 to effect disengage ment of the clutch, and the lower end of the bar is con--- nected by a link 232 to a solenoid 234 arranged to be: energized at a predetermined time, as will be described,. to rock the bar clockwise and permit engagement of the clutch 200. In operation the bar 222 is immediately released to effect disengagement of the clutch at the end. of one revolution. In order to prevent backlash of the: shaft 202 when the shaft is brought to rest, a spring-- pressed pawl 236 pivotally mounted at 238 is arranged! to engage a notch 240 formed in a ring 242 attached to the cam hub.

As illustrated in Figs. 1 and 2, each folding unit 12, 18, 30 is provided with its individual timing mechanism: 198, 199, 201 respectively, the transfer operating unit 22 being operated without a timing mechanism, as will be described. As illustrated in detail in Figs. 17 and 18,, each differential timing unit includes a cam disk 250 haw ing a cutout 251 arranged to cooperate with a roller 252 carried by an arm 253 forming a part of a stop switch 254. The cam disk 250 is also arranged to cooperate with a second roller 255 carried by an arm 256 forming part of an adjustable limiting switch 258 for closing a circuit to the solenoid 234 for releasing the one-revolution'clutch to elfect operation of the tucking or folding arm at a predetermined time during the advance of the sheet.

The cam disk 250 is' mounted to rotate on a shaft 260 and is provided on each side with magnetic contact disks 262, 264 arranged to cooperate with independently driven magnetic clutches 266, 268 respectively, also mounted to rotate on the shaft 260, the clutches 266, 268 being rotated at different speeds and arranged to be selectively energized to attract and rotate the cam disk 250 at one speed or the other as'determined by the photo-sensitive as will'be described. The cam disk 250a is. providedwith abushing270 and is freely rotatable;- on a spacingsleeve 272 interposed between the two magnetic clutches266; 268, and in order to reduce the effect of residuaLmagnetisrn when one clutch is deenergized and. the other energized, relatively thin brass spacers 274, 276 may be provided between the contact disks and their respective clutches.

The supporting shaft 260 is mounted in bearings formed in side frames 278, 28f) of the differential timing unit, and as shown in Fig. 17, the magnetic-clutch element 268 is arranged to be drivenat a relatively fast speed through spur gears 282, 284 having a ratio of one to oneconnecting the clutch element to a drive shaft 286 rotatably mounted in the side frames. The other clutch element 266 is arranged to be driven from the shaft 286 through a train of gears indicated at 288 at a relatively slower speed, preferably at a definite ratio relative to, the magnetic clutch 268, such as one-half, one-third or other ratio relative to the speed of the opposing clutch element 268, the gearing 238 being designed to permit interchange and adjustment of selected gears to obtain the desired relative speed.

The shaft 286 may be driven from the main drive of themachine, as shown in Fig. 1, through a chain and sprocket drive 290 connecting roller shaft 292 to a countershaft 294; and a chain and sprocket drive- 2% connecting the shaft 294% the shaft 286. Adjacent timing units 19?, 201may be connected to the shaft 286 through chain and sprocket drives 298, 300 respectively.

In operation the magnetic clutches 266, 263 of each unit are continuously driven in definite timed relation to the advance of the conveyer belts ofthe sheet-folding mechanisms through the driving connections described, and each magnetic clutch 266, 268 is arranged to be energized through the usual brushes 3G1, 302 and 303, 304 supported in an insulating block 305 for engagement with contact rings 396, 307 and 383, 309respectively. The contact brushes may be connected in circuits arranged to be selectively closed by firing of the photosensitivedetecting element as effected by the passage of the leading and trailingedges of'the sheet to be folded, as will be hereinafter more fully described.

As illustrated in Fig. 18, the stop switch 254 is fixedly mounted in a bracket 310 attached to the base of the timing unit. The roller arm 253 is pivotally mounted in the bracket and is urged upwardly by a spring 3R2 supported between an extended portion of the bracket and the underside of the arm. A stud 314 adjustably carried in the arm 253 is arranged to engage the stop switch 254. The limit switch 258 is arranged to be adjusted radially of the cam disk 25%, and as herein shown is mounted on a U-shaped bracket 316, the legs of the U being secured to collars 317, 318 fast on the supporting shaft 26 A worm gear 32%) fast on the shaft 269 is arranged to mesh with a worm 322 fast on the end of a vertical stud 324 rotatably mounted. in a bearing 326 formed in the side frame 280. The stud is held in position by upper and lower collars 327, 328- and a knurled knob 330 is provided-at the upper end of the stud. Thus, in operation the position of the limit switch relative to the stop switch maybe adjusted tothe desired position for effecting-folding of the sheet at a predetermined point as will presently appear.

The operation of the present. sheet-folding mechanism is diagrammatically illustrated in Figs. 19 to 22 showing the first folding station 12 with the sheet to be folded, as indicated at 8,. in different positions relative to the photo-sensitive detector 14 and the tucker arm 56, and in Figs. 18 and 23 which illustrate the different positions of the timing cam 250 withrelation to the advanceof the sheet onthe receivingconveyer 10.v As shown in Fig. 19, the distance from the photo-sensitive detector 14 to the' centerline of thetuckervfingerstdl) comprises apredeterminedand-fixed distance, indicated by theletter x, andthe trawl piitheibeltltl throughsuchfixeddistanceds definitee 1y. relatedto the arcuatedistance travelled by the cam of the. limit switch 258-.during. the. same period of time,

such arcuate distance being indicated'by the letter y in. Fig.- 23'. Inotherwords, the distance travelled in inches by the-belt-lt) per unit of time is related to the distance travelledinxdegrees per unit of time of the cam disk 250. For example, if itis assumed that the fixed distance x is 31 /2 inches and the arcuate distance y is 315", each 1 of. travel of the belts 10. will beequal to 10 of arcuate movement of the cam-.disk250. Now, if the length L of the sheet to be folded is assumed to be 48", and it is desiredtofoldthesheet centrally or exactly in half, when" theleading'edgeofihe'sheet Scuts olf the light source. of thezdetectorl i, a circuit .is closed to energize the slowly rotatedimagnetic clutch 266' which through the gearing 28S: isarranged inthepresent example to travel at onehalf thenormal speed relative to. the belt travel, or in other words, at a rate-of 5 for 1" of belt travel. The clutch element 266- thus energized attracts the earn 250 to causerotation thereof with the. clutch 266 so that during the travel-tot the sheetthrough its full length of 48" past the detector 14; the'cam disk.250 is rotated through an angulardistance which-in the present example comprises aldistance of 4S' S' or 240. Simultaneously with the start of thez-cam-diskt2s0, thestop. switch 254 is operatedto close a holding circuit, as will be described, and when the cam disk 250" has travelled through the 240 the trailingendofthe sheet'isin alignment with the detector 14 as. shown invtFig; 20 and the centerline of the 48" sheet is 24" distant: from the detector, that is one-half the length-ofzthe sheet indicated by L/2 in Fig. 20. Now, sincethe fixed distance xis 31 /2", the remaining distance for the sheetto'travel to dispose the centerline thereof in alignmentwith the tucker 56 is 31 /2"-24" or 7 /2".

During the; continued advance of the sheet, when the.

trailing-edge thereof passes beyond the detector 14 to again expose thedetector to the light source, the circuit to the magnetic clutch 266is opened and another circuit is closedrtoenergize: the 1 to .1 speed magnetic clutch 268, thus attracting the cam disk 250 to travel therewith at a rateof 10- breach 1' of belt travel. Thus, since the cam disk- 250- has'already travelled 240 and the total travel toeifect tripping .of the limit switch is 315, the remaining. travelof :the disk is 315 240 'or which at the-rateof 10 per one inch of belt travel will effect tripping .of:the.li'mit switch 258 when the sheet has travelled .the remainingzW/z to align: the center of the sheetwith .th'eifoldi'ng ;arm56. Closing of theswitch 258' is arranged to energize the .tucker unit solenoid 234 to release the oneirevolution:clutchiand permit the'cam 212 to makeone :revolution toperform the tucking operation, as shown; in Fig. 21. To complete the cycle of operation, the camdislo250 continues its rotation through the vremaining 45 to itsstartinggposition,.thus operating the stopswitch 254 to open the circuit to the clutch 268 and causing th'e: cam disk to come :torest, as shown in Fig. 18. Fig: 22 shows the tucker arm 56 'returnedito its'initial position andthe folded sheet beingadvanced' between the-. belts62, 20 toward the second folding station 18, as diagrammatically indicated in Fig. 19.

In-another' example, assumingthat the sheet to be folded isa36 inches :in: length, during :the passage of the 36*inch. length .past the-detector 14, the earn 250 will be rotated atone-half the normal speed so that when the trailing edge of the sheet reaches the detector the center-' line ofthe; sheet will be 18 inches beyond the detector and ethetcam; will have travelled 180 of the 315 total.

leaves the detector,.the cam will be causedto rotate at full speed; and when. the cam has rotated the remaining of the 315 total, the centerlineof the sheet'willbe:

aligned.withrthecfoldingstation and the tucker-operated gtotperfomrthefdlding operation;-

In practice the fixed distance x and the related arcuate distance y may be arbitrarily chosen with regard to the maximum length of the sheet to be folded. For example, the fixed distance of 31 /2 inches will accommodate any sheet up to a maximum of twice this distance or 63 inches if the sheet is to be folded centrally. If the fixed distance x is changed, the arcuate distance y may be correspondingly changed by adjustment of the limit switch 258 relative to the cam in the manner described. If the sheet is to be folded in thirds, the ratio of the gearing 288 for the magnetic-clutch element 266 may be changed to eifect rotation of the cam 250 at A of normal speed during the passage of the sheet past the detector 14. Thus, if a 36" sheet is to be folded in thirds, the cam 250 will have rotated 120 when the folding center is 12 inches beyond the detector and 19 /2 inches from the tucker. Then, during the full-speed portion of the cycle, the sheet travel of 19 /2 inches will correspond to an arcuate movement of 195 to trip the limit switch 258 to perform the folding operation. It will be apparent that the sheet thus folded in /3 at the first folding station may be folded in /2 at the second folding station to complete the folding of the sheet in thirds.

The second folding station 18 and the fourth folding station 30 are similar in construction and mode of operation to the first folding station 12 described, each being provided with a differential timing unit 199, 201 respectively associated therewith so that further description thereof is thought unnecessary. The transfer or third fold station 22 does not require a timing unit since the line of fold at right angles to the first and second folds is determined by initial placement of the sheet on the receiving conveyer relative to the position of the transfer bar as described. However, the passage of the leading edge of the twice-folded sheet to intercept the light source of the photo-sensitive element 24 is arranged to trip the transfer operating unit 138 to perform the transfer operation as described.

Referring now to Figs. 7 and 8, for a more detailed description of the transfer mechanism 22, the connecting elements between the transfer linkage 22 and the sheetelevating linkages 107, 109 are arranged to permit the transfer linkage to be immediately returned to its initial position after the transfer operation while the elevating linkages 107, 109 are permitted to remain in their upwardly rocked position until the longer edge 111 of the two laterally trailing edges of the sheet passes beyond the photo-sensitive detector 24. As illustrated in Fig. 8, the parallel arm 90 of the transfer linkage 22 is pinned to a cross shaft 350 supported in the machine frame and is arranged to be rocked by the transfer operating unit 138. The other parallel arm 92 connected by the bar 94 is loosely mounted on a parallel cross shaft 352. As shown in Fig. 12, the hub of the transfer arm 90 is provided with clutch teeth 354 arranged to cooperate with similar teeth 356 formed in the elongated hub 358 of the elevating linkage 109 on one side of the transfer station, and a collar 360 also pinned to the shaft 350 is provided with similar teeth 362 arranged to cooperate with teeth 364 formed in the elongated hub 366 of the adjacent elevating linkage 107 on the other side of the transfer linkage, such elongated hubs 358, 366 being loosely mounted on the shaft 350. The corresponding elongated hubs 368, 370 are pinned to the cross shaft 352 as indicated at 372, 374 in Fig. 7. As shown in Fig. 12 the grooved portions 376, 378 of the pinned collar 360 and arm 90 are cut longer than the teeth 364, 356 respectively so as to permit relative movement of the transfer linkage with respect to the elevating linkage. Thus, when the parts are in their lowered position, as shown in Fig. 13, the teeth 362 of the collar 360 are in contiguous engagement with the teeth 364 of the hub 366, the teeth 354, 356 being similarly engaged so that when the shaft 350 is rocked clockwise to perform the transfer operation, the elevating units 107, 109 are simultaneously rocked 10 as indicated in Fig. 14. The transfer linkage immediately returned to its initial position by upwardly, 22 is then virtue of the transfer operating mechanism 138 while the mechanisms remain in their upwardly rocked trailing edge 111 of the sheet passes beyond the photo detector 24, see Fig. 2. As shown in Fig. 7, the shaft 352 to which the hubs 368, 370 are pinned, is provided with an arm 380 fast thereon arranged to cooperate with a solenoid operated latch 382, as illustrated in detail in Fig. 16. The latch 382 is pivotally mounted at 383 and is urged into latching position by a spring 384 so that in operation when the transfer unit is rocked the arm 380 is retained in its rocked position to hold the elevating units 107, 109 up. The latch 382 is also connected by a link 385 to a solenoid 386 arranged to be energized to release the arm 380 when the detector 24 is tripped upon passage of the trailing edge 111 into the upper folding unit as described. As illustrated in Fig. 2, the fourth fold tucker arm 124 is connected to its operating unit 194 by a link 388 and a two-armed lever 390 pivotally mounted at 391, the second arm 392 having a roller 393 cooperating with the cam 394.

Referring now to Fig. 24, the wiring diagram for the present sheet-folding machine includes the photo- sensitive detectors 14, 16, 28 and the magnetic- clutch timing mechanisms 198, 199, 201 associated therewith and operatively connected to their respective solenoids 234, 234a, 23% forming a part of the tucker operating units 134, 136, 194 for the first, second and fourth folding stations respectively. The wiring diagram also includes photo-sensitive detector 24 operatively connected to solenoid 234c forming a part of the transfer or third fold tucker operating unit 138. Since each folding unit for performing the first, second and fourth folds is similarly connected in the diagram, it is believed that a description of the wiring for the first folding unit will snfiice for each.

As herein shown, the photo-sensitive detector unit 14 is connected to the main- power supply lines 400, 401 through leads 403, 404, and a direct-current circuit connecting the detector unit 14 with the magnetic-clutch unit 198 may be supplied with power from a transformer 406 through leads 408, 409, the transformer being connected to the main lines by leads 410, 411. Each photosensitive detector unit is provided with a switch 412 arranged to be actuated to close a circuit at contact 413 to energize the slowly rotated magnetic-clutch element 266 when the leading edge of the sheet intercepts the light source, and to close a circuit at contact 414 to energize the faster moving magnetic-clutch element 268 when the light source is again exposed by passage of the trailing edge of the sheet beyond the detector unit.

In operation when the leading edge of the sheet intercepts the light source, the circuit is closed through leads 408, 415, switch contact 413, and lead 416 to one side of the magnetic-clutch element 266, the circuit being continued on the other side of the clutch element 266 through leads 417, 418 and 409 to complete the circuit and effect rotation of the timing cam 250 at a slow rate of speed. As soon as the cam 250 starts to rotate, the normally open stop switch 254 is closed, and when the trailing edge of the sheet passes beyond the detector to againexpose the light source, the circuit is opened at contact 413, and a circuit is established through leads 408, 415, contact 414, lead 419, stop switch 254, lead 420, through relay contacts 422, and leads 424, 426 to one terminal of the magnetic-clutch element 268, the circuit being completed through lead 428 from the other terminal and leads 418, 409 to the transformer 406, thus effecting rotation of the cam 250 at the faster speed,

1 1 as described. The'relay, indicated a't 430, may comprise a telephone type electromagnetic relay, and-in operation when the normally open limit switch 258 is closed' momentarily by the cam 259, as indicated inFig. 23Lthe' relay 430 is closed by lead 420 from the closed stop switch 254 through limit switch leads 431, 433 to one terminal of the relay 430, and from theother terminalthrongh leads 435, 418', 409 to the transformer 406. The relay is held closed by the holding contacts 432 of the relay 439, as indicated in Fig. 24. Simultaneously therewith, the circuit is opened at relay contacts 422 so thatthe current to the fast-moving clutch element 268 is shunted through a resistor 434' for the purpose of reducing the clutch-holding strengthduring-the remainder of' the rotation of the cam 250' to its stop position, as

will be described. Operation of the relay 430 is also arranged to close contacts 436 in acircuit including an auxiliary relay 438 and a charged condenser 440,- the auxiliary relay 438 being arranged to be momentarily closed by the charge on the condenser 440. The'aiixiliary relay in turn is arranged to close atucker solenoid switch 442 to energize the solenoid 234to" enable the tucker operating unit 134 to perform the folding-opera= tion. The solenoid 234 forms part of a circuit connected to the main leads and includes leads 444', 446frm the main lead 400 to one terminal of the solenoid, then through switch 442 connected to the other terminal and leads 448, 458 and 451 back to the main lead 401;

In practice it is desired to have the solenoid -234operate as quickly as possible, that is, to be'energized'and particularly to be thereafter rapidly deenergized to'effect' release of the one-revolution clutch 200and operation of the folding unit 134, the rapid deenergization being desirable to effect quick return of the release arm 222 to clutch-disengaging position so as to prevent more than one revolution of the clutch 200 each cycle of operation. This is accomplished by means of the auxiliary relay 438 which is only momentarily closed'by'the stored'charge of electricity on the condenser 440 to close-the solenoid switch 442, and in practice the charge onthe condenser 440is quickly'discharged so that the solenoid 234 is ener gized only momentarily, the discharge of the condenser elfecting deenergization-of the auxiliary'relay 238 and deenergize the solenoid 234 P opening of the switch 442 to in a minimum time. The condenser 440 is permitted 'to be recharged between cycles of operation-by means of a selenium rectifier 452, the charging circuit including-- 185d leads 444, 453 through the selenium rectifier 454, and resistor 455 to one terminal of the condenser 440. The circuit is continued from the condenser through leads 448, 45% and 451 as shown. 7

During the continued rotation ofthe magnetic clutchelement 268 the cam 2-50 opens the circuit at the stop switch 254, thus discontinuingoperation of the magnetic clutch unit and deenergizing the relay 430. A'sabove described, during the latter portion of rotation of the cam disk 250, the current to the magnetic-clutch unit 268- is shunted through the resistance 434 which reduces the field current on the magnetic element 268enabling it to continue its rotation of the cam250 but deenergizing'the magnetic element sufficiently so that when the cam'reaches the stop position the residual magnetism will be'so low that the cam will come to rest withth'e roll'252 seated in the cutout 251 of the cam, as shown in Fig. l8,in'readiness for a succeedingcycle of'operation.

The second and fourth folding stations 18'and 3tlar'e similarly operated through similar wiring connections" from the main leads 400, 401 as indicated in Fig.241 The" transfer or third fold operating'unit' 138 is arranged to'be operated immediatelyupon' detection of the leading edge of the twice-folded sheet byth'e photo-sensitive detector" 24. As shown in Fig. 24,'the solenoid 234c isincluded inf a circuit'comprising leads 444, 456, solenoid234c',"switch" 458and leads 460,451, and in practice the SWltCh QSS'iS arranged to be momentarily "closed an auxiliary relay detector 24; the detector switch is closed at contact 466 to energize the" auxiliary relay 462 to-effect' momentary closing of switch 458 topermit operation of the transfer operating'me'chanisrn 138 for one revolution, as described. The condenser 464- may be recharged between cycles of operation through a" circuit'connected to the main lead 400 through le'ads 444", 453, selenium rectifier 452, lead 474; resistor 475 and lead 465 to the condenser 464, the

circuit being continued from the'condenser through lead 451 to the mainlead 401.

' As previously described, the elevating linkages 107, 109 an maintaining the sheet being transferred above the moving belts ZOduring the transfer operation are latched in'their elevatedpo'sition by the latch member 382' connected to the solenoid 386. As shown in Fig. 24, the solenoid 386 is included in a circuit from the main line comprising leads 444, 478 to the solenoid 386; the'circuit being continued through the solenoid switch 380, leads 481; 471 and 451 to the mainline. The switch 480 is arranged to be momentarily closed by an auxiliary 482 which is provided in a circuitincluding: a charged condenser 484 and arranged to'be' closed through detector switch contact 486. Thus, when the trailing edge 111 of the'sheet passes off the elevating linkage into the upper folding section 26 to again expose the light source to the detector 24, the detector switch is'closed at contact 486 to energize the auxiliary relay 482'and effect momentary closing of the switch 480 to energize the latch-release solenoid 386 and permit the elevating linkages 107, 109 to be returned to their lowered position, as described. The condenser 484 may be recharged through the selenium rectifier 452-and resistor 488' during the time between cycles of operation.

A switch 490 may be provided for each operating unit whereby to render inoperative one or another of the units while permitting operation of the remaining units.

From. the above description'it will be seen that the present sheet-folding machine is capable of operation upon sheets of varying lengths to effect automatic foldingof the sheet at a predetermined point in its length as determined bythe novel control mechanism' including photo-sensitive detecting means actuated by the leading 1. In a sheet-folding machine for folding sheets of' varying lengths, in combination, sheet-folding means, means for advancing a sheet into operative relation to the folding means, and control means including a single photo-sensitive detector disposed at fixed distance in advance of said folding means fordetecting the passage of the leading and trailing edges of the sheet being advanced into folding position, a difi'erential timer responsive to said detector for actuating said folding means, said timer including a cam operative through a distance related to .said fixed distance and to the rate of advance of the sheet and having two magnetic clutches selectively responsive to said single detector for cooperation with said are, means for driving said clutches at different speeds relative to the'advance of the sheet, one of said clutches being drivenat areduced rate proportionate to the division to i be made by the fold when said leading edge intercepts the detector, the other clutch being driven at a rate corresponding to the advance of the sheet when the trailing edges pass the detector whereby to effect folding of the sheet at a predetermined point in the length of the sheet, said timer cam being mounted intermediate said magnetic clutches and adapted to be selectively attracted to one and then the other thereof upon passage of said leading and trailing edges respectively, a limit switch cooperating with said cam and circumferentially adjustable relative thereto arranged to actuate said folding means when the sheet has been advanced into operative position to be folded, and a fixed stop switch cooperating with said cam for discontinuing the operation of said timer at the end of one revolution to terminate a cycle of operation.

2. In a sheet-folding machine of the character described, sheet-folding means including a one-revolution clutch, and a circuit including a timer and a solenoid arranged to be energized by said timer for releasing said one-revolution clutch, and an auxiliary relay circuit for operating said solenoid having a charged condenser arranged to operate the auxiliary relay whereby to effect rapid deenergization of said solenoid to prevent more than one revolution of said clutch, and means for recharging said condenser between cycles of operation.

3. In a sheet-folding machine of the character described, means for supporting and continuously advancing a sheet to be folded, a first sheet folding unit including a tucker member operative to form a transverse fold relative to the direction of advance of the sheet, a second sheet-folding unit cooperating with said first unit and including a pair of cooperating rolls disposed above said advancing means and a tucker member operative to form a longitudinal fold relative to the direction of advance of the sheet, said second tucker member effecting transfer of the sheet from the advancing means to said rolls of the second folding unit, control means including means for detecting the leading edge of a sheet to be transferred for actuating said second tucker member, and elevating means operating simultaneously with said transfer operation for bodily elevating the entire sheet above said continuously advancing means whereby to terminate forward movement of the sheet during the transferring and folding operation.

4. A sheet folding machine as defined in claim 1 wherein the cam is provided with magnetic contact disks, and relatively thin brass spacers between the contact disks and their respective magnetic clutches whereby to reduce the effects of residual magnetism when one magnetic clutch is deenergized and the other energized.

5. A sheet folding machine as defined in claim 1 wherein the sheet folding means includes a cam for operating said folding means, a one revolution clutch adapted to permit rotation of said cam, and solenoid operated means actuated by said timer for releasing said clutch.

6. In a sheet folding machine of the character described, in combination, means for supporting and continuously advancing a sheet to be folded, sheet folding means including a pair of cooperating rolls disposed above said advancing means, and an elongated tucker member arranged to transfer the sheet from the continuously advancing means to said rolls to form a longitudinal fold relative to the advance of the sheet, and means for bodily elevating the entire sheet above the level of the advancing means to terminate the forward advance of the sheet during the transfer operation.

7. In a sheet folding machine of the character described, in combination, a first sheet folding unit including means for supporting and continuously advancing a sheet, and means for forming one or more transverse folds in a sheet moved therealong, a second sheet folding unit disposed above said continuously advancing means for forming a fold at right angles to said transverse folds, an elongated tucker member arranged to transfer the sheet from the advancing means to said second sheet folding unit, and means for bodily elevating the entire sheet above the level of the advancing means to terminate the forward advance of the sheet during the transfer operation.

8. In a sheet folding machine of the character described, in combination, a first folding unit including means for supporting and continuously advancing a sheet, and means for forming one or more transverse folds in a sheet moved therealong, a second sheet folding unit disposed above said continuously advancing means for forming a fold at right angles to said transverse folds, an elongated tucker member arranged to transfer the sheet from the advancing means to said second sheet folding unit, means for bodily elevating the entire sheet above the level of the advancing means to terminate the forward advance of the sheet during the transfer operation, and control means including means for detecting the leading edge of a sheet to be transferred for actuating said tucker member and said elevating means, means for retaining the elevating means in its raised position after the tucker member is lowered, and means responsive to the passage of a trailing edge of the sheet being transferred beyond said detecting means for releasing said retaining means.

References Cited in the file of this patent UNITED STATES PATENTS 1,687,587 Pearne et al Oct. 16, 1928 2,034,040 Johnson Mar. 17, 1936 2,280,954 Kahn Apr. 12, 1942 2,291,487 Myers July 28, 1942 2,308,155 Clegg Jan. 12, 1943 2,330,977 Johnson Oct. 5, 1943 2,374,779 Preston May 1, 1945 2,458,544 Watson Jan. 11, 1949 2,545,798 Sjostrom Mar. 20, 1951 2,572,472 Gn'flin Oct. 23, 1951 2,652,246 Kagan Sept. 15, 1953 2,659,598 McLagan Nov. 17, 1953

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