US2625394A

US2625394A - Sheet stacking machine

Info

Publication number: US2625394A
Application number: US88441A
Authority: US
Inventors: Lawrence S Brown
Original assignee: Sperry Corp
Current assignee: Sperry Corp
Priority date: 1949-04-19
Filing date: 1949-04-19
Publication date: 1953-01-13
Anticipated expiration: 1970-01-13

Description

L. 5. BROWN 2,625,394

SHEET STACKING MACHINE Jan. 13, 1953 Filed April l9, 1949 14 Sheets-Sheet l L. 5. BROWN SHEET STACKING MACHINE Jan. 13, 1953 14 Sheets-Sheet 2 Filed April 19, 1949 Jan. 13, 1953 5, BROWN 2,625,394

Y I SHEET STACKING MACHINE Filed April 19, 1949 1 4 Sheets-Sheet s" 1953 L. s. BROWN 232 :5394 SHEET STACKING MACHINE Filed April 19; 1949 14 Sheets-Sheet 4 01 Q 0 q v n t N Q 3 I\ 3nventor Jan. 13, 1953 14 Sheets-Sheet 5 Filed April 19, 1949 I k I Jan. 13, 1953 3 BROWN SHEET STACKING MACHINE l4 Sheets-Sheet 6 Filed April 19, 1949 1953 L. s. BROWN SHEET STACKING MACHINE l4 Sheets-Sheet '7 Filed April 19, 1949 65 Zhwentor L4 WEE/V65 .5. 5 90 w v Jan. 13, 1953 L. s. BROWN SHEET STACKING MACHINE 14 Sheets-Sheet 8 Filed April 19, 1949 lllllllllll Gttorneg' (/85 Inventor- 1953 1.. 5. BROWN SHEET STACKING MACHINE Filed April 19, 1949 14 Sheets-Sheet 9 VT L (Ittomeg 1953 L. 5. BROWN SHEET STACKING MACHINE l4 Sheets-Sheet 13 Filed April 19, 1949 31mm or u/ 5m: 5. BROWN.

Ctttomeg Jan. 13, 1953 1.. 5. BROWN 2,525,394

SHEET STACKING MACHINE Filed April 19, 1949 14 Sheets-Sheet 14 W IHHH P 1 1533 I Jnneutor LA WEE/V65 J, 5E0 w/v.

Gttorneg Patented Jan. 13, 1953 sneer STACKING MACHINE Lawrence S. Brown, Massapequa, N. Y., assignor to The Sperry Corporation, a corporation of Delaware Application April 19, 1949, Serial N0. 88,441 4 Claims. (Cl. 271--79) This invention relates to a machine for stacks ing large sheets of flexible material, such as paper, which are delivered thereto at high speed, as from a high speed rotary printer. H

It: :has for an object to provide a machine of the above type which is capable of progressively stopping; the forward motion of the sheets and laying them horizontally on a stack in smooth unwrinkled condition.

Another object is to provide a machine of the above type which is capable of being adjusted to operate with sheets of various sizes and at various delivery speeds. Y

Another object is to provide, in a machine of the above type, controlled ejector means for ejecting a single sheet for purposes of inspection.

A more specific objectis to provide a stacking devicewhich is capable of operating with high speed rotary presses.

Various other objects and advantages will be apparent as the nature of the invention is more fully disclosed. I

The novel features which are characteristic of this invention will be better understood by referring to the following description, taken in con- 2 Fig. 12 is a section similar to Fig. 11 showing the parts in a difierent position;

Fig. 13 is a section taken on the line l3-l3 Fig. 12 illustrating a detail of the ejector mechnection with the accompanying drawings in,

which a specific embodiment thereof has been set forth for purposes of illustration. In the drawings: Fig. 1 is a horizontal section of a stacking machine embodying the present invention, taken on the line l-'-I of Fig. 2;

Fig. 2 is a vertical longitudinal section through the machine, taken on the line 2-2 of Fig. 1; 1

Fig. 3 is a broken horizontal section similar to i Fig. 6 is a vertical section similar to Fig. 2 but on an enlarged scale, showing the sheet receiving end of the machine;

Fig. 7 'is a vertical section similar to Fig.. 6 showing the stacking end of the machine;

Fig. 8 is a vertical section similar to Fig. showing the parts in a different position with the lower end of the ramp broken away; I

Fig. 9 is a detail view showing the lower end of the ramp; D

Fig. 10 is a broken horizontal section showing the sheet conveyor and gripper bars;

Fig. 11 is an enlarged section taken on the line ll-Il of Fig. 3 illustrating the timingv adJustment mechanism;

speed of the sheet.

anism;

Fig. 14 is a section taken on the line I4-l4 of Fig. 12 showing the timing cam;

Figs- 15 and 16 are sections taken on the lines I5-l 5 and I6|6, respectively, of Fig. 11;

Fig. 17 is a vertical section through the transfer chain taken on the line I'|-I7 of Fig. 10 but on a larger scale;

Figs. 18, 19 and 20 are sections taken on the lines l8l8, I9l9 and 20-20, respectively, of

Fig. 17 showing the construction of the gripper bars;

Fig. 21 is a detail section taken on the line 2l-2l of Fig. 22;

Fig. 22 is a section taken on the line 2222 of Fig, 21;

Fig. 23 is a section taken on the line 23-23 of Fig. 21;

Fig. 24 is a horizontal section taken on the line 2424 of Fig. 22;

Fig. 25 is a section similar to Fig. 22 showing the parts in a diflerent position;

Fig. 26 is a section similar to Fig. 23 showing the parts in a different position;

Fig. 2'7 is a diagrammatic view of the drive mechanism for the transfer and conveyor chains;

Fig. 28 is a section taken on the line 28-28 of a Fig. 29 is a section taken on the line 29-29 of Fig. 27;

Fig. 30 is a detail sectional view of the drive mechanism;

Figs. 31 and 32 are detail perspective views showing parts of the transfer mechanism.

Referring first to Figs. 1 and 2, a web 35 is delivered at high speed from a machine such as a rotary printer over a delivery roll 36, between a pair of guide rolls 31, and around an idler roll 38, thence around drive roll 39 to a cutting station comprising a stationary knife 40 and a rotary knife 4| mounted on a rotor 42. The rotation of the rotor 42 is timed to cut the web 35 into sheets 34 of the desired length.

From the cutting station the sheets 34 are fed to a sheet conveyor shown as a set of belts 43 travelling at a speed higher than that of the web and passing around rollers 44 to 48.

The belts 43 deliver the leading edge of each of the sheets 34 to a gripper bar which at that time is in aposition to grip said edge and is travelling at a speed somewhat less than the forward The gripper bars as they advance from right to left as seen in Figs. 1 and 2 are decelerated by the mechanism to be described until they are brought to rest at a point over the left hand side of the stack whereupon the gripper bars are opened to release the out sheets 34 onto the stack. The gripper bars 50 travel in an endless circuit and after releasing the sheets are accelerated until they are brought to their proper speed for gripping the next sheet.

An air blast 52 from a row of nozzles 53 is directed against the upper surface of the sheet 3 after the sheet has been gripped by a gripper bar 90 so as to cause the sheet to be removed rapidly from the belts 0i; and to fall onto the previous sheet on a ramp 53. Due to the fact that the gripper bars 50 are moving at a slower speed than the belts 43 the sheet immediately forms a catenary loop as it is gripped by the bars 50. The air blast 52 is directed onto this loop and serves 1 to pull the trailing end of the sheet from the conveyor belts 43. A second air blast 54 from a row of nozzles 58 is directed against the lower end of the sheet to cause the same to lie fiat against the ramp 55. As the successive sheets are gripped by gripper bars which are progressively displaced, the sheets lie in shingled formation, the trailing edge of the last sheet extending below the edge of the preceding sheet and lying against vacuum pad 9i which is carried by the ramp "-55 and which assists in holding the lower edge of the sheet flat against the ramp.

The stack 5i rests on a platform 00 which is progressively lowered by chains 6i as the stack increases in thickness, so that the top of the stack remains at substantially the same elevation.

Referring to Figs. 2, 3, 5, 6, a and 9, the ramp 55 is shown as comprising a frame '55 hinged at the top' over a roller Gii'and carrying across bars 07, 88 and 00. The crossbar 61 is fixed to the framers and carries a plurality of spaced vertical I rods 50 on which the sheets rest. The cross bar 0 8'is adjustable along the frame '05 and may be secured in adjusted position by bolts TI. The cr'dss bar 08 carries a plurality of spaced vertical rods I2. i V w H v} The cross bar 09 is mounted for vertical adjustment on aslide '53 which is slidably mounted on the frame 06 and is secured in adjusted position by bolts I4. The slide I3 also carries the vacuum box 5! having a perforated top plate I5 over which the lower edge of the cut sheets fall. A plurality of spaced vertical rods iii are mounted on the cross bar 09. A plurality of similar spaced bars H are mounted on a cross bar I0 attached to the slide I3. The central rods are rigidly mounted on the cross bars as by welding. The rods at the two sides of the ramp, however, are made adjustable so that the ramp may be adjusted to various w'idthsof web. For this purpose the various rods at the two sides of the ramp are mounted on U-shaped brackets 80, BI and 82 (Figs. 8 and 9) "which are, respectively, slidable along the cross bars 61, 00 and 69 and may be set in adjusted position by means of set screws. The inclination of the ramp may be adjusted by means of a bar 05 attached to the frame I55 and sliding in a strap 7 86 which is clamped to a stationary bracket 01 by means of a bolt 00. I

A vacuum pad as is positioned to engage the trailing end of the bottom sheet as it leaves the 4 ramp 59 to disengage the sheet for release onto the stack 5I.

Referring now to Figs. 17 to 20, each gripper bar 50 comprises a pair of end plates I00 carrying rollers IOI which travel in tracks I02 attached to the frame of the machine and forming an endless path; A transverse tube I03 is attached to the end plates I00. This tube carries an elongated stationary jaw member I04 at its lower side and at its top carries a toothed bar I05.

Movable jaw members I06 are mounted on brackets I01 which are journalled to rotate about a transverse tube I08 which is also secured to the end plates I00. The brackets I01 carry arms I09 having a plurality of spaced notches I I0 on their under sides to receive pins H5 to which are at tached springs III. The notches IIO permit adjustment of the spring tension.

Brackets II2 are also journalled about the tube I08 and have at their upper ends pawls I I3 which are adapted to engage the teeth in the bar I05.

The upper ends of the springs I I I are attached to pins II4 on the upper ends of the brackets H2. The brackets I01 and H2 are slidable along the tube I08 for purposes of adjustment in accordance with the width of the sheet to be gripped, and the engagement of the upper ends I I3 of the brackets I I2 with the teeth in the bar I 05 secures the same in adjusted position.

A shaft I20 is journalled in the end plates I00 and extends through holes I2I in the brackets I I2 which have suflicient clearance with the shaft --I20 to permit the necessary pivotal movement of the brackets II2 about the tube I08.

The shaft I20 carries pawls I22 which engage rollers I25 carried by the arms I09 and serve to depress the arms I09 when the shaft I20 is rov tated into the position shown-in Fig. 19, thereby opening the movable jaw members I00 against tension of the springs III. Theshaft I20 is actuated by rollers I23 carried on arms I24 attached to the shaft I20.

As shown'in Fig. 8, when the gripper bar 50 approaches'its gripping station in its path around the circularportion MP of the track I02, the

' roller I23 engages'a stationarycam I28 which depresses the roller as itadvances in a clockwise direction around the cam I28'so that the gripper jaws 100 are opened before the gripper bar reaches its lower position. The roller r23 then rides over the surface of an adjustable cam I30 which retains the jaws in open position until the rollerreaches'the end of the foam I30 at which point the roller is released'and the jaws are closed by the springs I I I.

As shown in Figs. 12 and 14, the cam I30 is in the forin'of a stepped cylinder which is mounted V on a shaft I 3 I for rotation by a worm I32 and worm gear I33 from a transverse shaft I34 which extends across the machine and as shown in Fig. 3 and is provided at it's end with an actuating arm I36 having a handle I31. The arm I36 may be latched in various positions bfzicljustment by means of aspring' pin I38 engaging holes in a plate I39 (Fig.4) A similar adjustable cam I30 is mounted at each side of the machine for actuating'the rollers I23 on the two end plates I00 and are adjusted in unison by the shaft I34. The

purpose of the adjustable cams I30 is to adjust the gripping position of the gripper'bars 50 in accordance with the size of the sheet being stacked. The transverse positions of the various movabte jaws I06 "is also adjusted in accordance "with the width of the sheet 34 and they are' so disposed as to pass between the various conveyor shafts belts 43 (Figs. 1 and 10). As indicated in Fig. 10, the conveyor belt roller pulleys 44 are adjustably mounted on a shaft I45 which, as shown in Fig.

v8, is'mounted on a sliding bracket I50 having a rack II adjusted by means of a gear I52 for varying the position of the discharge ends of the belts 43 as desired.

Referring to Fig. 6, the sheet 34 is fed on the belts 43 under a stationary guide plate-I55. The plate I55 is provided over certain of the belts 43 with a pair of holesin which balls I 56 rest. These balls are held in a cage I51 and are adapted to ride on the sheets 34 being fed and to hold the same in contact with the belts 43. In order to eject a sheet for purposes of inspection, a rock'lever I60 is provided at each side of the machine (Figs. 11 to 16) and is pivoted about a shaft I6I extending across the machine. Each lever I60 is provided with a lower (cam) surface I62 to engage the rollers I23 of the gripper bars 50. When the surface I62 is in raised position as shown in Fig. 11, there is sufiicient clearance to allow the rollers I23 to remain in their gripping positions. When the surface I62 .is tilted downwardly, however, as shown in Fig.

12, it engages the rollers I23 and depresses the same to release the clamping jaws I06 as the gripper bars 50 progress from right to left as seen in Figs. 11 and 12.

The lever I60 is actuated by a link I64 which is secured at its free end to a block I65 and is normaLy held in its right-hand position as seen in Figs. 11 and 12 by a spring I65. A transverse shaft I61 extends across the machine through elongated slots in the links I64 and carries cams I68 which are adapted to engage the blocks I65 when the shaft I61 is rotated in either direction and thereby shift the blocks I65 and links I64 to the left. An actuating handle I may be provided to actuate the shaft I61.

In order to cause the machine to eject only a single sheet a latch is provided in the form of a member I1I pivoted at I12 to the lever I60 and adapted when the lever is depressed to engage a plate I13 carried on a fixed bracket I14. A spring I is positioned to hold the member I1I in latched position. The member I'll also carries a release pawl I11 which is adapted to be engaged by the roller I23 as the roller passes thereunder, so that the roller elevates the pawl about the pivot I12 and releases the latch I1I from beneath the plate I13, thereby allowing the spring I66 to return the parts to their original positions so that the roller I23 on the following gripper bar is not actuated. When the roller I23 is actuated by the surface I62 to open the clamping jaws I06 the sheet of paper which is held by the clamping jaws is released and falls onto the floor so that it can be inspected without stopping the machine.

The gripper bars 50 are fed along the machine by means of a transfer chain I85 (Figs. 1 and 3) on each side of the machine which passes over sprockets I86 and I81, and a conveyor chain I88 on each side of the machine which passes over wheels I89 and I90 (Fig. 1). The transfer and conveyor sprockets I86 and I89 are mounted on I9I and I92, respectively, which are driven by means to be described. The drive for the chains I85 and I88 i illustrated in Fig. 27 as comprising a drive shaft I95 which is driven at a constant speed by a source of power not .shown. The shaft I95 carries a gear I96 meshing with a gear I91 carried on a shaft I93. The .shaft I98 carriesa gear .I99meshing with a gear 200 on a shaft I carryin an arm 202 in which a, pin 203 is journalled. I

The pin 203 carries a gear 204 to, which is attached an arm 205 carrying a roller 206 displaced from the axis of the pin 203 the same distance as the displacement of the axis of the pin 203 from the axis of the shaft MI. The gear 204 meshes with an internal stationary gear 201 to form an epicyclic train which is so designed that, as the'gear 204 is driven around the gear 201, the roller 206 oscillates in a straight linein a direction normal to the plane of the paper as seen in Fig. 27 and with a linear harmonic motion.

The roller 206 engages a slot 2l0 in the forked end of a lever 2I2 which is attached to a shaft 2I3 and thus serves to rock the shaft 2I3 with oscillating motion which is very nearly rotary harmonic.

The shaft 2I3 carries a segment gear 2I4 (Fig. 28) meshing with a segment gear 2I5 attached to a shaft 2I6 and so arranged that the shafts 2I3 and 2I6 operate in opposite directions and by an amount determined by the relative radii of the segment gears 2I4 and 2I5. The segment gear 2I4 also meshes with a segment gear 2I1 carried by a shaft 220 which is connected by segment gears 22I, 222 tooscillate a shaft 223. The shaft 223 carries a segment gear 224 meshing with a segment gear 225 carriediby a gear 226 forming one side of a differential 221.

The shaft 2I6 also carries a segment gear 230 meshing with a segment gear 23I on a shaft 232 carrying a segment gear 233 meshing with a similar gear 234 carried by a gear 235 forming one side of a differential 236. The connections are such that the input gears 226 and 235are oscillated in synchronism and in the same direction but by different amounts which may be adjusted by suitable selection of the segment gears 230 and 23I.

The shaft I98 carries at its far end a gear 238 meshing with a gear 239 carried by a gear 240 forming the opposite side of the differential 236. A gear MI is driven by the gear 239 and is attached to agear 242 forming the second side of the differential 221. Hence the

gears

240 and 242 of the two differentials are rotated in opposite directions and by different speeds which depend upon the ratios of the

gears

238, 239 and 24I.

The spider 245 of the differential 236 is attached to a shaft 243 carrying a gear 241 meshing with a gear 248 carried by a shaft 249 which, through beveled gears 250 and 25I, drives the shaft I9I. The

gears

241 and 248 may be changed for varying the drive ratio. The spider 253 of the differential 221 is attached to a shaft 254 which, through

beveled gears

255 and 256, drives the shaft I92. The shaftsI9I and I92 are thus driven in the same direction, but at different speeds each of which varies with thetimed motion introduced by the oscillation of the

gears

235 and 226, and the average rates of which differ in accordance with the various gear ratios. The gears are so selected that the maximum speed of the transfer chain I is somewhat less than the rate of feed of the paper sheet 34, preferably between 60% and 85% of the linear rate of feed of such sheet, and the minimum speed of the transfer chain I85 is equal to the maximum speed of the conveyor chain I88. The

.minimum speed of the conveyor chain Iifll'is tioned variations :is equal tothe time; interval between delivery of successive sheets a to .the gripper bars. The mechanism for selectively connecting. vthe gripper bars 56 to 'be-drivenbythetwo sets of I chains is illustrated in Figs..21 to26. Referring 'to these figures, each end plate Hill carriesv an .arm 2B0 having-a pairof. pinstzfil and 262 on -which two pairs-of clamping

jaws

263, 254. and 265, 266'are mounted. The jaws 263 .andZGfl ia-re interconnected by a pin 26? andslotlfiiito cause the jaws 283-and ZM-When elevated tothe positions shown in Fig. 23 to engage a .feed pin 2B9 carried by the conveyor chain 488, and. when retracted in the position shown in Fig. 26. to release such pin. Similarly '

theclamping jaws

265 and 265 are interconnectedby a pin 21 [and slot 212 tocause the jaws to operate in unison so that when elevated as shown in Fig. 25 they enagage a feed pin 213 carried-by the transfer chain A I85 (Fig. 21) and when retracted as shown in Fig. 22 they are released from said pin.

'For selectively actuating the twosets of clamp- "ing jaws a cam plate 233 is provided which is pivoted about a pin 28G carried by the bracket -26D and carries a pairof lugs 282 and 283 (Fig. 31) which are adapted to engage

shoulders

284 and 285 on

jaws

263 and 263, respectively, for retracting one of said jawsand advancingthe -'other as the cam plate 289 is shifted about its axis. The cam plate is also provided with

surfaces

286 and 281 which contact the respective "

shoulders

284 and 285 for locking either the

jaws

263 and 254 or the

jaws

265 and 256 in elevated positions. The shoulders 2-S8'and 2B9on theplate 280 form stops tolimit'the movement thereof.

' In order to prevent the plate 238' from moving when not actuated by external means a-pointed cam surface 292 is provided engaging a roller 293 mounted on an arm 2% which is pivoted to.

a pin 295 on the bracket 250 and is held inwardly by a spring 296. The roller 293, riding over the pointed cam surface 232, looks the plate 286 in either the position shown in Figs. 22 and 23 or "thepositionshown in Figs. 25 and 26. The connections are such that oneset of jaws engages -a-feed pin before the "other set of jaws has en- 'tirely released-its feed pin so as to avoid possibility of entirely releasing the gripper bar from *both chains during the shifting operation.

In order to shift the cam plate 280 'from'one position to the other, the plate is providedwith an arm 298 carrying. a roller 299 which engages suitable stationary cam surfaces atthe appropri- -ateplaces along the path of movement oi -thew gripper bars. As shown in Fig.5, theroller 299 i-engages a stationary cam 38% whichlis adapted .to force'the rollerdownwardly fcr shifting the iclamping jaws from :the transfer chain to the rconveyor chain. at that apointand engages a stationary cam 30! for shifting the clamping jaws from-the conveyor chain tothe transfer chain. uThese points are so selected thatat both points the feed pins-of the two chainsare in alinement I and traveling at the-same speed.

An adjustable cam E (Fig 7) controls-there- 'lease of the gripping jaws 19S. .TI'his cam 38% is .:mounted on a slide 353 having a rack 357i engaged .by a gear 3ii8-mounted on a shaft 389 for purposes of adjusting the point of release of the sheets by .the gripper bars. A handle 3) is provided -(Figs. 3 and. '17) for-actuating the shaft 3:39. A spring pin 3!! is carried in'the hub 3!.2 of the handle '3I0 for latching the handle in selected l. positions.

edge of each sheeth34xinto which the web iscut is fed by the belts 4,3 into the open jaws :of 1a gripper bar which is timed to receive thesame and at that instant is being advanced at nearly maximum speed by the transfer chain 155. The gripping jaws then close to grip the, for and end o h s e t an th r pper barmm iately begins to slow dow .due to t e sci lat n commoment i he rat o s ee o the trans er h n- When this curs the heet 4 orms a 10.01 du to the di f ren n eed b ween th gr er b and the belt a d s lew-n dcwnwerdlv-pv the a r t 2 i rm a sh n les s ack th "ram 5- A the ip er b r i d alo e b in ran er chai 8 and r ach s he po nts mi m m s ee o the ransfer ehein t shiiied 991 n o cha n 58 hic at tha time i tra l n at ts ma i um ed, T gr e r is thereafter d ong b t cor e r at varying rates through several cycles until it momentarily becomes stationary at the point of delivery where the sheet has been drawn cornpletely over the stack 51. The gripping jaws are then released to drop-the stationary sheet. The gripper then continues its travel on the conveyor chain until it is again shifted to the transfer chain which occurs after one ormore. cycles ,of travel and at an instant when the conveyor chain is. traveling at its maximum speed. Thereafter the transfer bar is advanced through one or more cycles by the transfer chain until itis again brought into sheet receiving position.

It is to be noted that each sheet is separately laid on the stack 5] and is separately .'br01 1 ht down from maximum speed to a condition of rest before it is released onto the stack. Hence the device may be used for stacking very thin sheets of material such as tissue paper weight which if not restrained would-tend to crumple if suddenly brought to restirom the high speed of the travel ing web.

Obviously if the rate ofs peedof the webisnot too great the gripper bars may be brought :frQm maximum speed to rest or nearly .so. by means of a single chain in which event the transier me n s ma be m ted n t ent o ve y h sp eds w er. ibis m ac to rate the speed of advance of --the gripper bars .from maximum speed. to a condition of rest during the small interval of time allowed between the presentation of successive sheets to the stacker mechanism.

Various changes and -modifications may :be made as will be apparent-to a. person skilled in the art. '7

What is claimed is:

1. A machine for stacking sheets of flexible m i fed t r to in areid a v nci e'rr n. m r si gs p ura it o awarenesbers, means ad ancinss id ppin members i a ess ath n succes ion 1 m a shee acei ins stat on throu h a s eet r le sin station back t t e sh re iving, station. said: -ad vancing means comprising a pair of conveyors operating in line in :theysame direction, means driving each of said conveyors at a variablerate which varies cyclically between amaxirnum and a minimum rate .of speed, the. maximumrateof thefirst conveyor :being somewhat less than .the rate .of advance ofsaid procession, the minimum rate: of said first conveyor :being equalv to the maximum rate of said second conveyor, the minimum rate of said second conveyor being substantially zero speed, means on said first conveyor to advance said gripping members from said gripping station to an intermediate point between said gripping station and said releasing station, means between the gripping station and the intermediate point for successively deflecting the trailing portions of the gripped sheets from the path of the succeeding sheets, means at said intermediate point to transfer said gripping members from said first conveyor to said second conveyor, means located at the point of minimum speed of said second conveyor to cause said gripping members to release said sheets and means in the said return path of said gripping members to re-transfer the same to said first conveyor.

2. A stacking machine as defined in claim 1 in which the deflecting means comprise blower means located at a point beyond said gripping station and arranged to remove the trailing ends of said sheets from the path of the succeeding sheets, whereby said sheets are caused to hang downwardly from said gripping members as they are advanced thereby.

3. In a stacking machine, as set forth in claim 1, an inclined ramp positioned beneath the path of travel of said gripping members between said gripping station and said releasing station, means withdrawing the trailing ends of said sheets from the path of succeeding sheets after the sheets have been gripped by said gripping members and causing said sheets to fall downwardly upon said inclined ramp in shingled formation, whereby said sheets are pulled upwardly over said ramp by said gripping members as they advance to said discharge station, suction means disposed on said ramp to cause the trailing ends of said sheets to lie flat against said ramp.

4. A stacking machine as set forth in claim 1 in which each of the gripping members comprises a bar disposed transverse to the direction of movement of the conveyors and carrying a plurality of sheet clamping jaws, and has means associated with the bars for gripping both conveyors, and there are cam means operative upon the gripping means and disposed in their paths to cause the said means at one point to grip the first conveyor and simultaneously to release the grip on the second conveyor, then at a succeeding point to release the grip on the first conveyor and simultaneously grip the second conveyor and then at the said one point again to grip the first conveyor.

LAWRENCE S. BROWN.

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

UNITED STATES PATENTS Number Name Date 533,444 Dejonge Feb. 5, 1895 1,156,903 Henderson Oct. 19, 1915 1,540,687 Feistel et a1 June 2', 1925 2,226,674 Seybold Dec. 31, 1940 2,300,863 Bamford Nov. 3, 1942 2,332,863 Luehrs Oct. 26, 1943 2,381,430 Belluche Aug. 7, 1945 2,474,997 Wormser July 5, 1949 FOREIGN PATENTS Number Country Date 19,447 Great Britain Aug. 24, 1909 473,337 Great Britain Oct. 7, 1937 513,206 Great Britain Oct. 6, 1939