US2896946A - Sheet feeding apparatus - Google Patents

Description

July 28, 1959 H. BARRATT ET AL swam FEEDING APPARATUS 4 Sheets-Sheet 2 Filgd Jan. 7. 1957 AVI/E/v 702s: Hflnaw BARR/477" 717 lVsu/mv 541125-72 United States Patent SEEET FEEDXNG APPARATUS Harold Barrett, Thomas Newton Forrester, and George Herbert Wilson, Coventry, England, ass gnors to Courtaulds Limited, London, England, a British com- P y Application January '7, 1957, Serial No. 632,748

Claims priority, application Great Britain January 11, 1956 12 Claims. (Cl. 271-6) This invention relates to sheet feeding apparatus and in particular to apparatus for providing a substantially continuous flow of sheets from a series of discrete stacks.

In the viscose industry, cellulose pulp in sheet form is one of the basic raw materials. The pulp is usually delivered by the pulp manufacturers baled in stacks from which the sheets are taken individually for processing into alkali cellulose.

In one continuous method of manufacturing alkali cellulose, sheets of cellulose pulp are fed in a continuous manner to a slurry tank in which the sheetsare immersed in an aqueous caustic soda solution and are torn to shreds by a stirring device.

One sheet feeding apparatus is described in USA. Patent No. 2,253,140 in which a stack of sheets of cellulose pulp maintained in an upstanding position on a conveyor belt are fed at a predetermined speed to a blade sheet-separating means which reciprocates beneath the sheets and forces one or more sheets at a time from the forward face of the stack. In order to load the conveyor with fresh sheets, it is necessary to stop the operation of the machine while the loading is carried out manually. Such stoppages disturb the desired continuity of feeding. The sheets are placed adjacent to each other in an upstanding manner and are supported by sheet supporting members which are removed before reaching the blade sheet-separating means.

The object of the present invention is to provide a sheet feeding apparatus capable of delivering a substantially continuous flow of sheets from discrete stacks.

According to the invention, mechanism'for feeding stacks of rigid sheets to a picker operating at a uniform .when the last sheet of a stack has been picked, and a feeler adapted to disengage the high speed drive and engage the low speed drive upon a stack being presented to the picker.

Preferably the mechanism also has mechanism by which the stacks of sheets are turned into upstanding position at the picker. cradle in which the stacks are held while they are turned. The stacks may be delivered to the cradle by a conveyor which is controlled by a switch which is actuated by a cradle when it is in position to receive a stack.

The picker may either be a blade reciprocated in an upwards direction from beneath the stack so as to slice off one sheet or more at a time, or may comprise a rotatable disc having a cut-away portion forming a blade at its periphery.

Three specific examples of apparatus constructed in accordance with the invention are illustrated in the accompanying drawings in which,

Figure 1 is a front elevation of one form,

Figure 2 is a plan view of part of Figure 1 with a working part in a second position,

The stacks may be turned by a 2,896,946: Patented July 28, 1959 ice Figure 3 is an end elevation of part of Figure l with the working part in a third position,

Figure 4 is an enlarged view of a detail of Figure 1,

Figure 5 is a diagram of the control mechanism,

Figure 6 is a front elevation of a second form,

Figure 7 is a plan view of part of Figure 6,

Figure 8 is a plan view of a second part of Figure 6,

Figure 9 is a front elevation of Figure 8,

Figure 10 is a front elevation of a third form,

Figure 11 is a plan view of Figure 10 through XIXI,

Figure 12 is an enlarged detail of Figure 10,

Figure 13 is an enlarged detail of Figure 11,

Figure 14 is a plan view of a driving mechanism for the apparatus shown in Figure 10,

Figure 15 is a diagram of a controller for the driving mechanism, and

Figure 16 is a schematic view of an electrically actuated, fluid pressure supply means for actuating certain parts of the mechanism of the present invention.

In Figures 1, 2 and 3 stacks 1 of cellulose pulp sheets 2 are delivered by a conveyor belt 3 to a pusher or cradle 4 which lifts the sheets 2 over a curved track 5 and delivers them to a rotating picker 6. The picker 6 peels the sheets 2 from the stack 1 and delivers them one by one to a delivery conveyor belt 7 by which they are conveyed to a slurry tank (not shown) where alkali cellulose is formed in a continuous manner.

The pusher 4 is connected by two pivoted levers or arms 8, 9 to a frame member 11 and is caused to ride over the track 5 by means of a hydraulic ram 11 connected to the lever 9.

When the empty pusher 4 is in its lowest position as shown in Figure 2 it lies upon a bed 12 above which are supported two sets of rollers 13 placed between prongs 14 of the pusher 4. A spring loaded stop 15 is depressed by the central prong 14 which operates a switch 16 causing the conveyor belt 3 to deliver a stack 1 on to the rollers 13 above the pusher 4.

When the stack 1 is in position, it strikes a switch 17 which stops the belt 3, causes a feeler in the shape of a rectangular frame 18 to be raised by a double acting pneumatic cylinder 19 into the path to be taken by the stack 1 and operates the ram 11 causing the pusher 4 to rise.

The stack 1 is pushed along the track 5 and in order to maintain the front sheet 2 of the stack 1 in a substantially perpendicular position with respect to the track 5, the pusher 4 for some part of the distance is tilted forward (as shown in dotted outline at 20 in Figure 1) by virtue of the disposition of the pivot points of the lovers 8, 9.

The stack 1 is pushed up the track 5 rapidly until the leading sheet 2 strikes the frame 18 when the frame 18 exerts pressure on the stack 1 due to the pneumatic cylinder 19 holding it in a vertical position (Figure 3). This pressure tends to straighten the stack 1 and prepare it for the picker 6. The frame 18 is gradually moved against the pressure in the pneumatic cylinder 19 until a cam 21 fixed to the frame 18, releases a switch 22 which actuates an electrical circuit to open a source of air pressure to the appropriate end of the cylinder 19 causing the frame 18 to swing outwards to a position shown in full line in Figure 1.

The switch 22 also causes the rate of movement of the pusher 4 to be reduced to a predetennined metering speed at which one sheet 2 is presented to the picker 6 for each rotation of the picker 6.

The picker '6 (Figure 4) consists of a disc 23, having a blade 24 formed by cutting away a portion of the disc, mounted on a shaft 25 rotated by a driven belt 26 on a pulley Wheel 27. On each rotation of the picker .3 .6, the blade 24 peels .a sheet 2 away from the stack 1 and guided by a plate 28 deposits it upon the belt 7. After one sheet 2 is removed, the stack 1 is moved up a rdistance equal to about the thickness of a single sheet 2 in readiness for the next rotation of the picker.

When the last sheet 2 of the stack 1 has been picked, the pusher 4.is now ,in such a position that a protruding member 29 strikes a switch .36 which causes the pusher 4 to be rapidly returned to the bed 12 for loading with .a new stack 1.

The mechanism for :controlling the movement of the pusher is shown in Figure in which fluid pumped by a .pump33 immersed in a tank 34 and driven by a motor 35 is delivered at .high pressure to the ram 11 by one of two pipes 36, 37 selected by a four Way valve 38. Fluid is :also continuously delivered to the ram 11 by a metering pump 39 which is connected between the ttank34and the pipe 37 by a pipe 46. The valve 38 is operated by two solenoids 41, 42.

With the :pusher 4- in the loading position, the opera- .tion :of the switch 17 energizes the solenoid 42 and fluid from the pump 33 is directed through a balance valve 43 and pipe 37 to the right-hand side of the ram 11. :Fluid trapped in the left-hand side of the ram 11 by a piston 44 escapes by the pipe 36 the valve 38 and a .returnpipe 45 to the tank 34. The pusher 4 rises ripidly until the switch 22 is operated when the solenoid 42 is -de-energized. The valve 38 now blocks the supply of fluid from the pump 33 and the pipe 36 remains connected to the return pipe 45. Fluid pumped by the metering pump 39 continues to enter the right-hand side :of'the ram 11 and inches the pusher 4 forward at a predetermined speed correlated with the speed of the rotation of the picker 6, for the duration of the picking tperiod.

When'the last sheet 2 is removed by the picker 4, the switch 30 is operated as described above and the sole- :noid 4-1 is energized. Fluid from the pump 33 is now directed by the valve 38 to the ram 11 by way of the .pipe 136 :and the pipe 37 is connected to the pipe 45 providing an escape for fluid trapped in the ram 11 to the right ofthe piston 41.

The balance valve 43 is set such that it will allow the how .of fluid from ram 11 to tank 34 via pipe 37, : valves 43, 38 and pipe 45, when the pressure caused by forcing the piston to the right exceeds that developed by the auxiliary pump 39, this balance valve 43 is substantially closed to the fluid pumped through line 40 by the auxiliary pump 39 when this is used for moving the ram 11 to the left and thus lifting the stack 1.

The pusher 4 eventually reaches the bed 12 where it is held by the pressure of the ram 11 until the switch 17 is operated by a new stack of sheets 2 initiating another cycle.

The movement of the pusher 4 to and from the picking position is carried out as speedily as practicable so :that there is substantially no delay in the continuous .delivery of sheets 2 along the conveyor belt 7 to the slurry tank.

In operation, a stack 1 comprising approximately five hundred sheets is picked in about seven minutes and the time taken between picking the last sheet 2 of one stack .1 and the first sheet 2 of the next stack 1 is about seconds.

The apparatus shown in Figures 6, 7, 8 and 9 is similar to that described in respect of Figure 1 (like parts being given the same reference numerals) with the main exception that the reciprocating pusher 4 is replaced by a number .of cradles 46 joined together by chains 47 to form a continuous belt, which is driven by either a :fastimotor .48, or a slow motor 49 through a gear box 550 a chain 51 and a wheel 52.

The fast motor 48 is connected to the gear box 50 by atchain 53 which drives a sprocket 54- on .a shaft 55.

The slow motor 49 is connected to the gear box 50 by a chain 56 which drives a free-wheel 57 also mounted on the shaft 55.

The slow motor 49 normally drives the shaft 55 but is overridden by the fast motor 48, by virtue of the free wheel 57, when the fast motor 48 is brought into operation.

Each cradle 46 has a base 58 with supporting prongs 5h and wheels 60 and is guided by rails 61 on the track 5. Additional rail guides 62 are provided on the vertical portions of the rails 61. When the motor 48 is in operation, stacks 1 of sheets 2 are pushed up track 5 by the cradles 46 and on arriving at the picking position make contact with the feeler frame 18 waiting in a standing position. The frame 18 eventually is thrown outwards when the switch 22 is released as previously described, and the motor 48 is switched ofi. The chains 47 are now driven by the motor 49 and the cradles 46 are advanced at a speed correlated with the rate of rotation of the picker 6 to permit one sheet 2 at a time to be removed by the picker 6. The sheets 2 fall on to the belt 7 by way of the plate 28 and a secondplate 63 slotted at the top to permit passage of the prongs 59 of'the cradles 46.

When the last sheet 2 of a stack 1 has been picked,

a projection 64 on the cradle 46 strikes a switch 120 which starts the motor 48 thuscausing the chains 4-7 to carry the cradles 46 at a fast speed. At the same time,

the frame 18 is restored to its vertical position.

New stacks 1 are delivered to a slotted platform 121 having rollers (not shown) by a conveyor belt :122,-during the period when the cradles driven by motor 49 are advancing at a speed correlated with the rotation of picker 6. The new stack 1 when in position, strikes a switch 133 at the rear of the platform 121 which stops the conveyor belt 122. The next cradle 46, when driven by the fast motor 48, passes upwards through the .plat- .form 121, lifts the waiting stack 1 and carries it up track 5 towards the picker 6. The switch 133 is released setting the belt 122 in motion, and .a new stack 1 is delivered to the platform 121, the switch 133 is again operated and the belt 122 is stopped. Meanwhile, another stack 1 is presented to the picker 6, the motor 48 is stopped and the chains 47 .are again driven at metering speed by the slow motor 49.

The picking period for a stack 1 of about five hundred sheets is about seven minutes and the time taken to bring a new stack 1 to the picking position on completion of the previous stack 1 is about ten seconds thus maintaining a substantially continuous flow of sheets along the'belt 7.

In Figures 10 and 11, stacks -1 of sheets '-2 lying in a horizontal position are brought by a conveyor 65 to a cradle formed by pairs of rotatable arms at right angles in the form of a star .wheel 66 which deposits the stacks 1 in an upstanding position on an inclined conveyor 67 upon which the stacks 1 are carried to a chisel-nosed reciprocating picker 68. The sheets are sliced from the stacks 1 by the picker .68 and are guided by a plate 69 on to a delivery conveyor 70.

The conveyor 65 comprises four spaced belts 71, driven by means not shown, between which pass the arms 72of the wheels 66. The inclined conveyor 67 similarly comprises four spaced belts- 73 lying in line with the belts 71. The belts 73 are driven by a series of rollers 74 which in turn .are driven from a driven shaft 75 through a spigot 76, a chain 77, spigot 78 and a shaft 79. The lower ends of the belts 73 pass round a series of rollers 80 freely mounted on a shaft'81 to which are fixed the wheels: 66. The shaft 81 is driven by a chain 82 on a spigot 83 from a driving means not shown.

A stack I lifted from the conveyor 65 and deposited upon the conveyor 67 by the wheel 66 is carried up'the conveyor 67 by projections 84 fixed at spaced intervals on the belts 73. Co-operating with the projections 84 are arms 85 extending downwards from a belt 86 placed above the conveyor 67. The belt 86 travels between two rollers 87, 88; the roller 87 being connected by a chain drive 89 to a spigot 90 on the shaft 79.

The stack 1 is carried up the conveyor 67 rapidly until the leading sheet 2 strikes one or both of a pair of catch members 91 placed between and projecting above the belts 73 adjacent the picker 68. Each member 91 (Figure 12) is L-shaped and is pivoted at one end to a switch 92 and is capable of being lifted or lowered by a pneumatic cylinder 94, through an arm 93.

When the projecting tip of the member 91 in the lifted position is pushed forward by the leading sheet 2, the switch 92 is operated and the speed of the conveyor 67 is reduced to a metering speed so that sheets 2 are sliced from the stack 1, one at a time for each reciprocation. At the same time, the member 91 is lowered away from the stack 1 by the arm 93. The picker 68 is reciprocated by a crank 95. Placed in the space between the belts 73 just in front of the path of reciprocation of the picker 68 is a rocker 96 biased to one side as shown in full line in Figure 13. One arm of the rocker 96 is attached to a micro-switch 97.

The stack 1 holds the rocker 96 in a horizontal position during the picking period, but when the last sheet 2 is removed it returns to its normal position, operating the switch 97 causing the conveyor 67 to travel at speed and deliver another stack 1 to the picker without delay.

The shaft 75 is driven rapidly during the delivery period and at a predetermined rate during the picking period through a clutch mechanism shown in Figure 14. A clutch plate 98 freely mounted on the shaft 75 is driven by a chain 99 from a fast driving source (not shown) and a second clutch plate 100 also freely mounted on the shaft 75 is driven by a chain 101 from a slow driving source (not shown). Between the plates 98, 100 slides a co-operating clutch plate 102 keyed to the shaft 75 and capable of being pressed into contact with either the plate 98 or the plate 100 by an arm 103 operated by a pneumatic cylinder 104.

The speed of the conveyor 67 is controlled by an electro-pneumatic controller shown in Figure 15.

The pneumatic cylinders 94, 104 are both connected by two pipes 105, 106 to a two-way valve 107 to which is connected a compressed air supply pipe 108 and two vent pipes 109. Pistons 110 of the valve 107 may be shifted to the left by a solenoid 111, when compressed air is directed from the pipe 108 to the pipe 105 and the pipe 106 is vented. On de-energisation of the solenoid 111 a return spring 112 draws the piston 110 to the right when the compressed air from the pipe 108 is directed to the pipe 106 and the pipe 105 is vented.

When compressed air is connected to the pipe 105, the arm 103 connected to the cylinder 104 (Figure 14) slides the clutch plate 102 into contact with the plate 98 and in consequence the conveyor 67 and the belt 86 are driven at speed. Also, the members 91 are lifted so that their tips stand proud of the conveyor 67.

When compressed air is connected to the pipe 106, cylinder 104 causes the arm 103 to slide the clutch plate 102 into contact with the plate 100 when the conveyor 67 is driven at the metered speed for picking. Also the members 91 are lowered into the spaces between the belts 73 of the conveyor 67 The solenoid 111 is energized by an electric current from terminals 113 through a relay switch 114 closed by the energizing of a relay coil 115 in a secondary circuit supplied with electric current through terminals 116.

The relay coil 1-15 is only energized when three switches in the secondary circuit are closed, namely the microswitch 97 of the rocker 96 and both switches 92 of the two members 91. A relay coil hold-on switch 117 closed on energization of the relay coil 115 is connected in-parallel with the micro-switch 97.

Figure 15 shows the position when a stack 1 has been picked and the conveyor 67 is being driven at speed to deliver a new stack 1 to the picking position.

The rocker 96 is off-balance thus closing the switch 97, and the two switches 92 are closed while the tips of the members 91 are projecting into the path of the advancing stack 1.

As the stack 1 approaches the picker 68 it strikes the rocker 96 bringing it to a horizontal position thus opening the switch 97. This, however, does not atfect the relay coil 115 since an electric circuit is still maintaine through the switch 117.

When the leading sheet 2 of the stack I eventually strikes any one of the members 91, the associated switch 92 is opened and the circuit through the relay coil 115 is broken. The switches 114 and 117 are opened, the solenoid 11-1 is de-energized, the pistons in the valve 107 move to the right under the influence of the spring 112, and compressed air enters the pipe 106.

The conveyor 67 is now driven at a slow speed for picking and the members 91 are withdrawn out of the path of the stack 1 when the switches 92 again close. The rocker 96 is held in the horizontal position by the weight of the sheets 2 in the stack 1 until, in due course, the last sheet 2 is picked. The rocker 96 then tips offbalance so closing the switch 97. The circuit through the relay coil is again closed and the coil 115 closes the switches 1 14, 117. The solenoid 111 is energized, the pistons 110 of the valve 107 are moved to the left and compressed air is connected to the pipe 105. Again, the conveyor 67 is driven at speed and the members 91 are lifted so that their tips project into the path of the next advancing stack 1.

The stack 1 comprising approximately five hundred sheets is picked in about seven minutes and the time taken between picking the last sheet 2 of one stack 1 and the first sheet 2 of the next stack 1 is about five seconds.

Thus a substantially continuous flow of sheet 2 is maintained along the conveyor 70.

The means for actuating cylinder 19 under control of switch 22 may be of any preferred or conventional construction, one form being illustrated schematically in Figure 16, wherein pneumatic cylinder 19 is connected by two pipes .118 and 119 to a two-way, piston-type valve 123 and is provided at its opposite ends with vent or discharge pipes 124 and 125. Valve 123 is connected by pipe 126 to a source of compressed air. Piston 127 of valve 123 may be moved from its upper position where it closes the adjacent end of pipe 118 as shown in Figure 16, to its lowermost position by solenoid 128 when switch 22 is closed, whereon compressed air is passed from pipe 126, over the top of piston 127, through pipe 118 and into the upper portion of cylinder 19 above the piston 129 therein which forces said piston 129 and the parts connected therewith in a downward direction as viewed in Figure 16. During this operation, vent or discharge pipe 124 is closed and vent or discharge pipe is open. When switch 22 is opened, solenoid 128 is de-energized and a return spring 130 moves the piston 127 of valve 123 upwardly to the position shown in Figure 16, where it closes the adjacent end of pipe 118, whereupon compressed air is passed from pipe 126 through pipe .119 and into the lower part of cylinder 19 below the piston 129 therein which forces said piston 129 and the parts connected therewith in an upward direction as viewed in Figure 16. During this operation, vent or discharge pipe 125 is closed and vent or discharge pipe 124 is open.

When it is desirable to feed a blend of varying types of pulp sheets to a slurry tank, this can readily be achieved by having two or more sheet feeding machines, each Ti loaded with sheets of a particular'type of pulp, ifeeding sheets at predetermined rates-toa common conveyor belt.

The 'speedat whichthe sheets are picked 'ineach of the machines maybe controlled to suit operating conditions, for example, the speed'may be controlled by the levelof liquid in the slurry tank or by a Weight belt on which the sheets are fed to the slurry tank.

- What 'we claim is:

1. Apparatus for feeding stacks of rigid sheets of uniform thicknms stack by stack to a picker operating at a uniform rate comprising at least one carrier for carrying a stack to the picker, means to load a stack onto the carrier, a high'speed driving mechanism to move'the carrier to present the first sheet of the said stack to the picker, a low speed driving mechanism to move the car- 'rier to present subsequent sheets to the picker at a rate corresponding to the rate of operation of the "picker, a feeler operative upon a stack being presented to the picker to disengage the high speed driving mechanism and engage the low speed driving mechanism, and a detector operative when the last sheet of a stack has been picked to disengage the low speed driving mechanism and cause the high speed driving mechanism 'to present a loaded carrier to the picker.

2. Mechanism according to claim '1, in which the feeler is adapted to be engaged by the leadingsheet of a stack upon arrival of the latter at 'the picker, there being a switch adapted to be operated 'by the feeler when it is engaged by the leading sheet which switch disengages the high speed drive and also causes the feeler ;to be moved clear of the sheets.

3. Mechanism according to claim lin which the detector is actuated by the carrier.

4. Mechanism according to claim 1, comprising mechanism by which the stacks of sheets are turned into upstanding position for presentation to the picker.

5. Mechanism according to claim 4, having a cradle for turning the stacks.

-6. Mechanism according to claim 5, in which there are swinging arms carrying the cradle at high speed from a charging position to the picker, at slow speed while the sheets are being picked, and the cradle and arms are returned at 'high speed to the charging :position when the cradle is empty.

7. Mechanism according to claim 5 in which :there is a conveyor adapted to deliver the stacks to the cradle, in combination with a switch controlling the conveyor and adapted to be actuated by a stack when it is-delivered 'to the cradle.

8. Mechanism according to claim 5 in which there is arr-endless conveyor carrying the cradle, in combination with 'low speed and high speed drives therefor.

9. Mechanism according to claim 8, having at least two cradles, one of which is in position to be charged when another is feeding a stack to the picker.

l0. Mechanism according to 'claim 9 in which-there is a platform to position a stack for acceptance by :a cradle, in combination with a belt conveyor to deliver the stack to the platform and a stationary stop switch positioned to be actuated by a-stack of sheets when the said stack has been delivered by the conveyor to a position to be received by-the cradle, which switch acts *to stop the belt conveyor.

11. Mechanism according to claim 5, in which the cradle is formed by rotatable arms set at right ang'lesto each other, the means to load a stack onto the carrier comprising a feed conveyor, and there being a sloping belt conveyor for the carrier driven "by the "low speed and high speed drives adapted to turn up the stacks of sheets on the sloping belt conveyor at 'a point some distance from the picker. I 12. Mechanism according to claim 1-1, in which 'a second sloping belt conveyor is arranged above the first belt conveyor andis driven by the sai'd low speed 'andh'ig'h speed drives, both conveyors having cooperating arms to carry the stacks up the first sloping conveyor.

References Cited in the -file of this patent UNITED STATES PATENTS

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