US2328859A - Classifier - Google Patents

Description

7; 1943.l l. TAYLoR A cLAsSIFIER Original Fileddan. 21, 1939 4 snee'ts-sheet 1 Sept. 7, 1943. c. L TAYLQR .cLAssIFIER Ori nal Filed Jan. 21. 1939 4 sheets-sheet 2 A NORA/.frs

Sept. 7, 1943. y c. L ,frAYLoR cLAssIFIER Original Filed Jan. 21, 1959 4 Sheets-Sheet 3 -72A 73 97a v/NVENTO/. CL4/FENCE L. 7A YZOE A TroR/vfrs n C. l.. TAYLOR sept. 7, 1943.

CLASSIFIER originali-11m Jan. 21, 1939 4 .sheets-.sheet 4 Patented Sept. 7, 1943 aszasse CLASSIFIER Clarence L. TaylonYoungstown, Ohio, assignor to The Aetna-Standard Engineering Company, Youngstown, Ohio, a corporation of Ohio Original application January 21, 1939, Serial No. I

252,152. Divided and this application June 12, 1942, Serial No. 446,683

9 Claims.

This invention relates to a piling apparatus particularly adapted for use in classifiers for gauging sheet materials and separating the gauged sheets in accordance with variations in their thickness.` The invention is described I. herein in its application to the production of tin plate but it is to be understood that the invention may be used in conjunction with other materials and that the description of the preferred form of my invention contained herein is given only by way of example. This application is a division of my application Serial No. 252,152, filed January 21, 1939, Patent No. 2,291,261, July 28, 1942. The present application contains claims .directed more particularly to the mechanism whereby the sheets are accurately piled, without being damaged. The arrangement oi magnets disclosed herein is claimed more broadly in my copending application aforesaid, while structural features of the classifiers are claimed in 'my copending application Serial No. 446,684 flied of even date herewith.

Users of tin plate require that the thickness of the sheets furnished them be maintained within very close tolerances. Sheets that are too thick or too thin are likely to result in defective products or in the breaking of the dies of the can making machinery. Therefore it is essential for manufacturers of tin plate accurately to classify the sheets in accordance with their thickness to insure delivery of sheets of proper gauge totheir customer. For the sake of economy it is essential that the classifier apparatus operate of the classifier; and Figure 7 is an end elevation of the delivery end.

My apparatus is particularly adapted for use in conjunction with modern tin mills of the continuous type in which the metal is delivered after the rolling operation in the form of bright annealed eleetrolytically cleaned coils of tin plate which require only tobe shearcd to the proper length and classified according to thickness before being shipped to the customer. Ordinarily there are slight, but important, variations in the thickness of the rolled strip, and it is because of these variations that the sheets must be classified and sheets of the desired thickness separated from those sheets of greater or lesser thickness. The classified sheets must be piled accurately and rapidly and must not be damaged by the piling operation.

In Figures 1 and la I have diagrammatically illustrated a preferred layout of my apparatus for shearing and classifying'strips of tin plate formed ona continuous mill. As shown in the drawings', a strip S of tin plate is fed from a coil C by a suitable uncoiling device through an edge trimmer indicated at 20. This is driven by an electric motor 2i which exerts sufllcient tension to unwind the strip from the coil. Be-

at highspeed without damaging the sheets and that the classifier accurately pile or stack the sheets so that they can be handled conveniently.

Accordingly it is a general object of my present invention to provide an apparatus, particularly suited for use in a classifier, but also adapted for other uses, which is adapted to operate at high -speeds and to pile sheets accurately without damaging them.

Various other objects oi'. my invention will become apparent from the following Vdescription of a preferred embodiment thereof, reference being made to the accompanying drawings. The essential characteristics are` summarized in the claims.

In the drawings, Figures 1 and 1a diagrammatically illustrate a classifier embodying piling apparatus made in accordance with my invention showing the arrangement of the associated equipment;I Figure 2 is a diagram showing .a preferred wiring arrangement for the electrical controls for the classifier and associated equiplment:'liigure 3 is a side elevation of the' classifier. some of the parts being omitted for convenience of illustration; Figure 4 is a plan view of the feed end of the classifier; Figure 5 is a vertical section taken along line 5-5 of Figure ,3; `Figure 6 is a plan view of the delivery end yond the edge trimmer the strip is allowed to sag, as shown. to give a little slack in the strip to take care of fluctuations in the speed of the following apparatus, and is then passed through felt pads indicated at 22 which function to remove dust and chips from the strip. Then the strip is automatically gauged by a continuous gauging device 23.

From the gauge 23. the strip passes through a V roller leveler indicated diagrammatically at 24. pinch rolls 25, and thence to the rotary shear 26, the roller leveler, pinch rolls and shear being driven by a single motor 21. 'Change speed gears (not shown) are incorporated in the drive of the shear 2G so that the shear can be adjusted to cut different lengths of sheets. The construction and arrangement of the gears, shear and associated mechanism are well knownin the art and form no part of the present invention and accordingly will not be described further herein.

From the shear 26, the sheets are delivered t0 the'classier proper which is illustrated somewhat diagrammatically in Figure la. The details of the classifier will be described later, but for the present it will be sufficient to state that the sheets are deposited on a conveyor belt 3U 1,000 ft. per minute, it being desirable to space the ends of successive sheets a distance of approxim `tely 1 ft. Obviously the difference in speed b tween the belt 30 and the strip necessary to accomplish the desired spacing depends upon the length of'sheets being cut by the shear.

, After leaving the belt 30, the sheets if they are of proper gauge pass over the flipper or defiector 32 which is pivotally mounted on a shaft 33 and arranged to be raised or lowered by a solenoid 34 controlled by the continuous gauge 23. The gauge 23 and the control circuit for operating the solenoid 34 do not per se form a part of this invention, a suitable type of gauge being disclosed in United States Patent No. 2,007,840. For the purposes of this specification, it will suffice to say that in the present instance, the circuit is arranged so that the solenoid 34 is energized to raise the flipper 32 and thus deflect the sheets downwardly beneath the ipper in the event that the thickness of the strip material varies from a predetermined standard an amount in excess of the established tolerances, while so long as sheets of proper thickness are being delivered the solenoid will not be energized, the flipper will remain in substantially horizontal position as shown in full lines in Figure 3, and the' sheets will pass over the flipper and be delivered to the belt 35. The sheets upon delivery to the belt 35 may be traveling at very high speeds on the order of 1,000 ft. per minute. Necessarily the speed must be reduced gradually in order to make it possible to accurately stack the sheets without damaging their edges. Therefore the belt 35 is driven by the motor 36 at a reduced speed, say 820 ft. per minute, if the belt 30 has been operating at 1,000 ft. per minute. From the belt 35 the sheets pass the belt 31 where the speed is further reduced. In the example given, this belt may be driven at the speed of the shear, say 600 ft. per minute, the drive being accomplished by the motor 33. Thus fon belt 31, the sheets will be closely spaced.

From the belt 31, the sheets are discharged onto the final belt 39 disposed at a slightly lower level than belt 31 and driven at considerably slower speed. In the example given the speed of the belt 33 may be about 240 ft. per minute. Because of this very Aconsiderable reduction in speed, it will be evident that the sheets will be discharged into belt 39 in overlapping relationship. That is to say, they will be shingled as diagrammatically indicated in Figure 1a of the drawings.

From the belt 39 the sheets are passed between rolls 4U and 4| and over roll 42, all of which are driven in synchronism with the belt by the motor 43, and discharged onto the elevating platform 44. The construction and arrangement of the discharge mechanism and guides 45, 46 and 41 associated with the platform form an important part of my invention and will be described in detail below. The platform 44 is arranged to be raised or lowered by a suitable elevating mechanism indicated in general at 48, and in operation the platform is gradually lowered as sheets are discharged thereon.

In the event that a sheet of incorrect thickness is delivered onto belt 30, then by the control mechanism briefly described above the solenoid 34 will be energized to raise the flipper 32 to the full line position of Figure la of the drawings as the sheet approaches the solenoid. Thus they sheet will be deflected downwardly to the belt disposed beneath belt 35. Sheets of incorrect gauge are then carried along belts 31 and 33' similar to f various motors operating at correct relative belts 31 and 33 previously described: the belts being driven by motors 33', 33' and 43'. The discharge mechanism includes rollers 4|'. 42' and elevating platform 44' with associated guides 45', 46' and 41', the platform being raised and lowered by the elevating mechanism 48. The sheets are held against the various belts by magnets M and M'. These insure accurate positioning of the sheets and prevent the sheets from planing through the air, all as described in greater detail in my parent application aforesaid.

Preferably the apparatus should be readily adaptable for use in classifying sheets of tin plate of diierent lengths, widths and gauges. Thus the controls must be flexible so that the speeds of the various elements may be easily varied in order to obtain proper operating conditions. So far as I am aware the best operating speeds for each particular size of sheet can only be determined experimentally. Therefore a control system by means of which various speeds can be obtained readily without stopping the machine is essential to eflicient operation of the machine. To attain this end, I preferably provide individual motor drives for the belts, the shear and the edge trimmer as described above and provide each motor with an individual speed control so that its speed can be varied independently of the speed4 of every other motor. Further all of the motors may be stopped and started simultaneously and the speed of all of the motors may be varied simultaneously by means of a Ward-Leonard control system.

The wiring arrangement for this control is shown diagrammatically in Figure 2 in which the Ward-Leonard, or variable voltage, generator is indicated at 50. The field current of the generator is controlled by the rheostat 5i which thus varies the output of the generator. The current generated is delivered through conductors 52 and 53 to armatures of the motors 2|, 21, 3i, 36, 36', 38, 38', 43 and 43' which are all connected in parallel with the result that if the rheostat is adjusted, for example, to increase the field cur- I rent of the generator the speed of all of the motors will be increased, and conversely if the generator field is weakened the speed of all of the motors will be reduced. Individual control to separately l adjust the relative speeds of the motors is attained by the motor eld rheostate R-Z I, R-21, and R-3I, R-3B, R--36, lit-38, R-33', ft- 43 and R-43', respectively, which are carried by the frame of the classifier. Weakening the shunt fields of the motors by means of the rheostats increases their speed, and strengthening the fields reduces their speed. By this arrangement very flexible control is obtained. The speeds of all of the motors can be adjusted to best advantage by the various field rheostats and the entire machine can be stopped or started or varied in speed during operation by rheostat 5i without changlng the individual setting of the field rheostats. By this control scheme not only can the machine be operated to best advantage but also no time is wasted when the machine must be stopped, for instance to supply a new coil of material, as the entire apparatus can be stopped by the rheostat 5I and immediately started again with all of the speeds.

Referring to Figures 3 to '1, inclusive, it will be seen that the mechanism is supported on a suitable oor or base by frame members 60, 6I and 62 and suitable vertical frame members 53, 84 and 65 which are duplicated on opposite sides of the machine. The motors and associated driving mechanism are supported by a. girder or beam 66 which extends longitudinally o! the machine along one side thereof and which is supported' by the vertial members 63, 64 and 66. It will be noted that the girder 66 is a box construction and as shown particularly in Figure 6 supports all of the driving mechanism and `the belts, except for the supports furnished immediately adjacent the upright members 63, 64 and 65. Beneath the girder 86, longitudinally extending members 61 and 66 (Figures 3 and 5) are provided which function to support the eld rheostats Rf-3I, etc. for controlling the speeds of the individual motors, the backs of these rheostats being shown in Figure 3. By this construction, the driving mechanism and controls are all concentrated along one side of the machine, making them readily accessible to the operators, while the opposite side of the machine is open except lin the immediate vicinity of the vertical supports 63, 64 and 65. Thus the conveyor belts are readily accessible and can be replaced easily without tearing down the machine and because of its open construction the operation of the machine can be clearly observed so that any necessary adjustments can be made.

As previously pointed out, the sheared sheets are discharged from the shear 26 onto the conveyor belts 30 which operate on rollers or pulleys 69 and 69a, the pulleys 69 being driven by a shaft 10 while the pulleysl69a are idlers. The shaft 10 is supported by bearings 1| and 1|a mounted in bracket 16 at opposite sides of the machine, and at its end is provided with a sprocket 'l2 so that it may be driven by the motor 3| through the chain 13.

In order to provide means whereby the level oi' the belts 30 may be adjusted to accommodate the belts to variations in the level of the pass line through the shear, the bearings for the pulleys 69a are supported by suitable brackets 14 on longitudinally extending rods 15, which are in turn mounted on the transversely extending bracket 16 supported by bearings 18 in the girder 66 (see Figures 4 and 5). The end portion of the bracket 16 is concentric with the shaft 10 and the bearings 1| are disposed within the end of the bracket 16. Thus the bracket and arms may be rotated about the axis of shaft 10 to raise and lower the belts 30 without changing the distance between the pulleys 69a and the pulleys 69. The belts are supported at the desired level, either at or slightly below the pass line of the shear, by rods 80 pivotally mounted at their lower ends. to a suitable frame member or support 8| as at 82. At their upper ends, the rods are pivotally connected as at 83 to a transversely extending bar 84 extending within the belts and channeled to receive the rods 15, the bar being cut away to receive the rods and being provided with cover plates. 85 secured in clamping engagement with the rods 15. It will be evident that by loosening the screws 86. the bar 84 can be slid along the bars 15 in either direction to raise or lower the pulleys 69a. By this means the belts 30 can be adjusted vertically to a suiiicient extent to insure that the sheets will be properly delivered by the shear. Y

From the belts 30 the individual sheets pass either above or below the iiipper or deilector 32,

depending upon whether the sheets are of standard "thickness or not. The deiector 32 is mounted upon a shaft 33 which is supported for rotation by suitable bearings in the girder 66 and `3 in the bracket 89, mounted upon the frame member 63. The defiector 32 is rotated from one position to another by the solenoid 34 through a connectingrod and the shaft 33, the solenoid being actuated in response to changes in strip thickness as described above. As long as strip of standard thickness is being fed through the gauge, the deflector 32 remains in its lower position as shown in Figure 3 of the drawings, but if the thickness of the Strip varies either above or below the standard thickness by an amount exceeding the established tolerances the deflector will be raised to deflect the sheets downwardly onto the lower series of belts. Assuming that the sheets delivered to the belts 30 are within the established tolerances, then the sheets will be delivered over i deflector'32 to the belts 35, a roller 9|a. being interposed between the deflector and the belts to reduce the friction on the sheets in traveling between the successive belts.

The belts 35 are carried by pulleys 93 and 94, the arrangement being generally similar to the lsupporting mechanism described in conjunction with the belts 30; i. e., the'pulleys 93 are driven by a `shaft which extends through and is supported by a bracket 96, similar to the bracket 16, and mounted in suitable bearings carried by the girder 66. The end of the shaft 95 is provided with a sprocket 91 so that the shaft may be driven through the chain 91a. by vmotor 36. The idler pulleys 94 are supported by suitable bearings carried by brackets 98 mounted on rods 99 which are supported by the transversely extending bracket or arm 96.

To provide for vertical adjustment of the belts 35, a bracket '|00 pivotally mounted on the girder 66 by bar |00a and supporting a bar |0| generally similar to bar 84, is employed. The rods 99 and pulleys 92 may be raised and lowered by rotating the bracket |00 about its pivot and sliding the bar |0| along the rods. Only a small amount of adjustment is provided for the level of the belt 35 as no great range of adjustment is required.

The tension on the belts 35 can be adjusted by moving the brackets 98 along the rods 99 by means of nuts |02 in threaded engagement with the rods. A similar scheme is employed for acljustment of the tension on the belts 30.

As previously noted, only sheets of standard gauge are carried by belts 35, the velocity of the sheets as they are delivered to belts 35 is substantially the velocity of the belts 30, for example about 1,000 ft. per minute, and the slowing down of the sheets so that they can be stacked accurately and without damage is started on the belts 35. Thus the belts 35 may be operated at a speed of about 800 ft. per minute. From the belts 35 the sheets are delivered to belts 31 where the velocity is further reduced, preferably to such an extent that the sheets are deposited on the belt with very little space between the sheets. The belts 31 are carried by pulleys |03 and |04 and supported by a transversely extending bracket |05, rods |06 vand adjusting bracket |01, all substantially identical with the mechanism described for supporting the belts 35 The driven pulleys |04 are keyed to shaft |06a which is driven by motor 38 through chain |08 and sprocket |09.

The belts 31 deliver the sheetsto belts 39 which are driven by motor 43 through mechanism simi- -lar to that previously described at a velocity le s s less than the peripheral speed of'the shear. The belt is pretcrank arm 9| keyed to.

v31, so that the sheets are deposited thereon in overlapping or shingled relationship as indicated in Figure 1a and carried thereby in this shingle arrangement to the piler mechanism at the delivery end of the machine. The pulleys for supporting the belts 39 and the associated brackets are similar in all material respects to the mechanism described previously with respect to belts 35 and 31 except that two brackets H0, similar to the 4brackets |00 and |01 previously described, are employed in conjunction with two bars for supporting the longitudinally extending bars H2, because the belts 39 are considerably longer than the Vbelts 35 and 31, the 15 additional length being necessary to convey .the sheets beyond the piler mechanism for the olfgauge sheets which have been deflected by the flipper 32.

The velocity of the belts 39 may be, for example, about half the peripheral speed of the' shear, thus reducing the speed of the sheets to such an extent that they can be piled accurately without damaging the sheets. The piling appa ratus is illustrated particularly in Figures 3, 6 and '7. As illustrated, the sheets in their shingled arrangement on belts 39 are passed between the concave and convex fabric rolls 40 and 4|, the roll being driven by a chain ||1 and suitable j sprockets at substantially the speed of the belt 39. The rolls 4 0 and 4| are constructed of cotton or other suitable material 'much in the manner of bufiing wheels and are given concave and convex contours so that the sheets passing between the rolls are bent in such a manner that their upper surfaces are concave, thus increasing the rigidity of the sheets and preventing their vforward ends from bending downwardly until the rear portions of the sheets have been released, from the rolls. The overlapping of the sheets ini the pinch rolls also assists in the proper delivery i thereof, for the trailing edge of each sheet is held down by a following sheet, resulting in the projection of the sheets from the pinch rolls a substantially horizontal plane. 4"

To provide adequate pressure between the rolls 40 and 4|, the upper roll 40 is supported by bearings mounted on brackets |20 carried by a rotatably mounted shaft |2|. The adjustable springs |22 and |23, mounted on the main frame and engaging above and below lever |24 rigidly connected to shaft |2| maintain the-roll 40 in engagement with roll 4| with the desired pressure.

The sheets as they are discharged immediately assume their previous flat condition and are projected forwardly and downwardly onto a suitable platform 44 which may be elevated by the elevating mechanism 48 to a position so that the top of the pile of sheets is Within the area enclosed by the side guides 41 and the members 45. The position of the elevator may be manually controlled by any ordinary means, the practice being to gradually lower the platform as sheets are deposited thereon.

The stops or guides are carried by an arm |28 pivotally and slidably mounted on rod |29, and the end of the arm engages the underside of rod |30 as indicated at |3|. Thus the arm can be slid along to vary the position of the stop for different size `sheets and also can be swung upwardly and out of the way as indicated in dotted lines in Figure '1.

The side guides 41 project forwardly from and, are carried -by guide plates 46 (see Figures 3 and 1). The plates 43 and guides 41 may be moved toward or away from eachother along a supporting rod |3|a by screws |32 extending transversely of the end of the main frame member, the sheets being guided laterally by the side guides and being projected against the end guide or stop member 45 with the result that a straight pile of sheets is formed.-

To insure that ach sheet will be projected with suillcient velocity from the pinch rolls 40 and 4| to cause it to abut the end guide 45 and also to straighten out any sheets that may be slightly deflected in their travel through the machine, I preferably employ a roller 42 of polished steel driven by sprockets |34 and |35 and chain |38 at substantially the same velocity as the belt 39.

The sheets dropping from the grip of the pinchl I rolls are given a slight forward impetus by the roller which is suiilcient to straighten out the sheets and give them sufilcient velocity to cause them to be piled in a straight pile with their forward edges abutting thestop 45.

As previously described in connection with Figure/1a, the flipper 32 is raised by the solenoid 34 whenever a sheet of incorrect gauge is approaching the flipper so that any such sheets will be deflected downwardly under the lower series of belts as', 31' and 39' and finally discharged onto the elevating platform 48'. The arrangement of the belts and their driving mechanism is in all material respects the same as the arrangement of the upper series of belts described in detallabove, and the description will not be repeated here. Corresponding parts in the lower series of belts are marked with reference characters corresponding to those applied to the upper series.

By reason of its various novel features, my apparatus can accurately classify sheet material at very high speed. Because of my convenient control system, the various instrumentalities making up my apparatus can be readily adjusted to operate at the most eillcient speeds, and also all of the driving motors can be simultaneously started and stopped and their speed adjusted by a single control. The piling apparatus can be adjusted readily to accommodate different sizes of sheets, and for all sizes within the range of adjustment the sheets are accurately and uniformly piled without damage thereto. The

0 shingling of the sheets makes it possible to slow them down so that they can be piled accurately without damage and also assures proper delivery of the sheets by the pinch rolls. The flexible speed control arrangement makes possible the proper adjustment of the speeds of the various belts and rolls to obtain the desired amount 'of overlapping of the sheets and the proper discharge speed to insure accurate piling.

In the foregoing specification I have described in detail a preferred form of my invention. Various changes and modifications can be made therein without departing from the spirit and scope of my invention, and it is therefore to be understood that my patent is not limited to the preferred form described herein or in any manner other than by the scope of the-appended claims.

I claim:

1. In an apparatus for classifying thin sheet material, a series of conveyor belts for conveying the sheets through the apparatus, said belts operating at progressively slower speeds and the receiving end'of one of the belts being disposed below the discharge end of the immediately preceding belt whereby said sheets are deposited on said belt in overlapping relationship, means for regulating the speed of said belts, and means for 2,328,859 Apiling the material delivered by thel belts com-A erally horizontal plane until released by said pinch prising a. platform, a pair of pinch rolls comprising a concave roll and a. convex roll disposed one above the other and adapted to receive sheets delivered by said series of belts and to discharge said sheets` onto said platform, means for driving said pinch rolls, side guides and a stop member for guiding said sheets onto said platform, a roll Y ing at progressively slower speeds and the receiving end of one of the belts being disposed below the discharge end of the immediately preceding belt whereby said sheets arev deposited on said belt in overlapping" relationship, and means for piling the material delivered by the belts comprising a platform, a pair of pinch rolls comprising a concave roll and a convex roll disposed one above the other and adapted to receive sheets delivered by said series of belts and to discharge said sheets onto said platform, means for driving said pinch rolls, means for guiding said sheets onto said platform, a roll disposed adjacent the lower ofv said pinch rolls and adapted to engagev the trailing edges of the sheets as they are discharged from said pinch rolls` and means for driving said roll.

3. In an apparatus for piling thin metal sheets, the combination of a conveying mecha- -nism including a series ofl belts for conveying sheets through said apparatus, one of said belts lbeing adapted to discharge sheets onto another belt operated at a slower speed and disposed at a lower level than the discharge end of said rst belt, whereby sheets are deposited on said other belt in overlapping or shingled relationship, and 'means forvpiling said sheets comprising a pair of pinch rolls adapted to receive said sheets from said last named belt and to deliver said 'sheets onto a platform, the lower of said pinch rolls having a concaved surface and the upper' of'said pinch rolls having a convex surface whereby sheets passing between said pinch rolls are bent into a concave-convex form by saidpinch rolls and arexheld in such form in a generally horizontal plane until released by said pinch rolls and discharged onto said platform, and a driven roll disposed adjacent the lower of said pinch rolls and adapted to engage .the trailing edges of the sheets. f

4. In an apparatus for classifying and piling thin ferrous sheets, the combination of aconveying mechanism including a series of belts for conveying sheets through said apparatus at high speed,"one of said belts being adapted to dis-` charge sheets onto another' belt operated at a slower speed and disposed at a lower level than lthe discharge end of said first belt, whereby sheets are deposited on said other belt in overlapping or shingled relationship. magnets for holding said sheetsin contact with said belts, and means for piling said sheets comprising a pair of resilient pinch rolls adapted to receive said sheets from said last named belt and to deliver said sheets onto a platform, the lower of said pinch rolls having a concaved surface and the upper ofsaid pinch rolls having a convex surface whereby sheets passing between said pinch rolls are bent into a concavo-convex form by said pinch rolls and are held formin agenrolls, a stop member for guiding saidsheets onto said platform, and a driven roll disposed adjacent the lower of said pinch rolls and adapted 'to engage the trailing edges of the sheets as they are discharged from said pinch rolls to cause said sheets to squarely engage said stop.

5. In an apparatus for piling thin metal sheets, the combination of a conveyor belt, means for depositing sheets on said belt in shingled relationship, and means for piling said sheets comprising a pair of resilient pinch rolls adapted to receive saidsheets from said' belt and to deliver said sheets onto a platform, the lower of said pinch rolls having a concaved surface and the upper ofv said pinch rolls having a convex surface whereby sheets passing between said pinch rolls are bent into a concavo-convexform by said pinch rolls and are held in such form in a generally horizontal plane until released by said pinch rolls. a stop memberfor guiding said sheets onto said g platform, and a driven rou disposed adjacent the IIB lower of said pinch rolls and adapted to engage the trailing edges of thesheets as they are discharged from said pinch rolls to cause said sheets to squarely engage said stop.

6. In an apparatus for piling sheet material, an elevating platform, a pair of pinch rolls disposed one above the. other and adapted to discharge sheets onto said platform, means for driving said pinch rolls, a stop member for` guiding i said sheets onto said platform, a roll disposed adjacent the lower of said pinch rolls and adaptl ed to engage the trailing edges of the sheets as they are discharged from said pinch rolls to cause said sheets to squarely engage said stop, and means for driving said. roll.

7. In an apparatus for piling sheet material, a platform, a pair of pinch rolls disposed one above the other and adapted to discharge sheets onto v said platform, means for feeding sheets tosaid pinch rolls in shingled relationship, means for driving said pinch rolls, a stop member for guiding said sheets onto said platform, a roll disposed J adjacent the lower of said pinch rolls and adapted toengage the trailing edges of the sheets as they are discharged from said pinch rolls to cause said sheets to squarely engage said stop, and means for driving said roll. 4

8. In an apparatus for piling sheet material, a platform, a pair of pinch rollsdisposed o ne above the other and adapted to discharge sheets onto said platform, one of said rolls being concave and the `other convex, means for feeding sheets to said pinch rolls, means for driving said pinch rolls, a stop for guiding said sheets onto said platform, a roll disposed adjacent the lower or said pinch rolls and adapted to engage the trailing edges of the sheets as they are discharged from said pinch rolls to cause said sheets to squarely engage said stop, and means for driving said roll.

9. In an. apparatus for piling sheet material, a platform-.a pair of pinch rolls disposed one above the other and adapted to discharge sheets onto said platform, one of said rolls being concave and the other convex, meam fordriving said pinch rolls, means for guiding said sheets ontosaid platform, a roll disposed adjacent the lower of said pinch rolls and adapted to engage the trail- 'ing edges of the sheets as they are discharged

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