US2930493A - Apparatus for stacking and weighing sheets of wood pulp and the like - Google Patents

Description

suNDBLAD ETAL 2,930,493

2 Sheets-Sheet 1 March 29, 1960 K Y APPARATUS FOR sTAcKTNG AND WEIGHING sHEETs 0E woon PULP AND THE LIKE Filed Nov. 25, 1957 LU- P @om )1T TY.

March 29, 1960 K. Y. SUNDBLAD ETAL 2,930,493

APPARATUS Foa sTAcKING AND WEIGHING SHEETS OF WOOD PULP AND THE LIKE 2 Sheets-Sheet 2 Filed Nov. 25, 1957 Fig. 2

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APPARATUS FOR STACKING AND WEIGHING SHEETS F WOOD PULP AND THE LIKE Karl Yngve Sundblad, Broma, and Sigvard Valfrid Soderstrom, Hagersten, Sweden Application November 2s, 1951, serial No. 69s,s27'

` 4 claims. (cl.z14z) This invention relates to apparatus for building stacks, having uniform weight and dimensions, of sheets d elivered in adjacent rows. More specifically the invention relates to apparatus adapted to receive sheets of wood pulp, cut from a web as produced in a pulp mill, and arrange the sheets in stacks of predetermined weight and height for baling.

In a mill producing wood pulp, logs are cut and shredded mechanically and chemically into water borne fibrous particles and ultimately formed into a comparatively dry web of pulp. Near the delivery end of the pulp machine, when the pulp is to be shipped in bales, the web is sliced lengthwise into strips of equal width and then the strips are cut crosswise at fixed intervals to form uniformly dimensioned sheets. A quite common size of such sheets is thirty-six by twenty-four inches. The rows of sheets delivered by the machine are dropped upon a receiving platform in separate stacks or piles. l

`It has been the practice in the past forV workmen to transfer the stacks individually to a weighing scale and by manually adding or removing sheets to bring theY final stacks to approximately the desired bale weightwhich usually is a set figure of four or five hundred pounds. The designated weight forms the basis on which payment s made. After being weighed, each stack is wired or banded under compression into a bale for shipment.

In carrying out the above method the attendants wait until all the stacks reach a height roughly corresponding to that of a stack having the desired Weight and then transfer such stacks by conveyor or truck to the weighing scale. This practice heavily concentrates the labor at space intervals leaving idle time between.

Under the pressure of handling a numbervof pulp stacks in quick succession the weighing is 'clone hurriedly, with the workman transferring a handful ofsheets at a time to bring the stack near the desired weight. To avoid creating any underweight bales the Workman will almost invariably pile on eXtra sheets. Consequently, by giving more pulp than it is paid for, the producing mill may suffer considerable monetary loss.

Another objectionable feature of the practice of taking such stacks of the height, approximating the desired weight of the bale to be shipped, arises from the fact that the percentage of water in the pulp is generally greater toward the edges of the pulp web as it arrives from the 'pulp machine. At the same time the difference in the amount of 'water affects very slightly, if at all, the thickness of the web. Pulp usually handled in sheet form and shipped in bales has an overall moisture content often to fifteen percent. However, it may run as low as five percent at the center of the web andas high'as twenty percent along the borders. l

Accordingly, the sheets from the outside rowsv of the sliced web will be heavier due to their greater water content than those in the inner rows, while not being any Bales formed from the outside sheets do not require as many sheets to reach the desired weight and will be shorter than the bales built from the inner rows of sheets. This has several undesirable effects. One is that the lack of uniformity in size makes packing for shipping or storage more difficult. Another serious consequence is that the Water content of a bale built from the arent ree Y operations where the' water component must be uniform.

The principal object of this invention is to provide means for forming stacks of sheets of pulp as close as'possible to the exact weight desired in the final bale of pulp as shipped.

A further object of the invention is the provision of means for building bales-having uniform dimensions.

' Another important object is to provide apparatus for producing bales of pulp having the same over-all water content.

A still further object of the invention is the provision of means for automatically proportioning, stacking and weighing sheets of pulp.

The apparatus of the invention by which these objects are attained utilizes a conveyor arrangement placed crosswise of the delivery end of the pulp machine to receive the several rows of sheets delivered by the machine. For purposes of illustration, the particular apparatus disclosed herein is adapted to a pulp machine from which five-rows of sheets are discharged.

vTo accommodate such a machine the apparatus has five stacking stations separated by 'faisable dividers. A Weighing scale is associated with the stacking position receiving sheets from an end row. Power means are ar.- ranged for periodically moving the stacks the Width of onerow toward the end` where the weighing scale is located. Except for the end station with whichV the scale is associated, the Yconveyor arrangement comprises a ,reciprocable carriage with areas constituting receiving stations at progressively lower levels toward thev scale location. 1

In starting the operation of the apparatus vof this invention, it is desirable, but not ressential to first place sheets, preferably by hand, upon all stacking stations except the one at the opposite end from that where the weighing scale is situated, and away from which the conveyor periodically moves the stacks. Thepiles of sheets thus built arestepped up in size to that at the weighing scale station which is four fifths of the estimated height of a stack weighing the final desired'amount; the pile or stack in the station next to that of the scale station should be approximately three fifths of the estimated height of a full stack,` and those in the nexttwo adjacent stations two fifths, and one fifth respectively, the fifth and last station being left empty.

The larrangement of stacks as described applies to an apparatus of the invention adapted to. a machine from which ve rows of sheets are issued. A similar proportional division of sheets is built up by hand in connection with pulp machines delivering different numbers of rows.

The apparatus is then ready to receive the pulp sheets directly from the pulp machine. As soon asfenough additional sheets, approximately the last fifth of a full stack, have been deposited upon the stack at the weighing scale station to bring its weight to the desired point, a device immediately responsive'to the arrival of the indicating needle on the dial of the .scale'at the predetermined weight figure causes the delivery of sheets to be momentarily interrupted, the stack dividers to be raised, and Yeach partialstack moved one `station toward the scale position. Simultaneously, the stack having the correct final weight is moved away from the scale to a separatefconveyor for compressing and baling operations.

The shifting of the partial stacks is" accomplished through temporary advancement of the stepped carriage a distancek equal to the common row width and the :eten:

` 3- tion of the incomplete stacks vat their new stations through momentary holding of the stacks above and independent of the carriage while it is reciprocated back to its original starting'place. The sheets .that .have meanwhile been intercepted in their dow-from the pulp machine .are then dropped .upon lthestations and :the regular deliveryof the sheets is resumed. The apparatus is .more :specifically described :hereafter in connection with the drawings .in which: p n

Figure 1 is a elevation of an apparat-us .embodying the invention .as viewed from the vline I--I of Figure 2; and

Figure 2 is a vertical section of the :apparatus Vof :Figure v l taken `on the line Il-Il thereof.

Referring to the drawings in :more detail, the .apparatus is supported upon two heavy end posts 10, and against pillars 12 through horizontal arms 14 extending from the top of the posts. Overlying and joining the arms 14 is a cross member 16. A platform 18 is positioned on the vdoor beneath the arms. The platform 18 includes two hollow side beams 20 lying horizontally in parallel relationship. These beams support the tracks 22 for the four-wheeled carriage 23, which has a general stairway form. One wheel 24, of each pair of wheels of the carriage is equipped with flanges 26 for engaging rail 22, while the other wheel 28 of each pair is `not flanged. The casing 30 of the carriage supports the axles 32 on which the wheels 24 and 28 are mounted. The latter are within the casing as shown in Figure 2.

From the upper side wall of the casing, extending in the directionY away from the pillars 12 there is a series of horizontal pins 34, four at .the level of each step 36 of the stairway outline of the carriage. These sets of pins andthe stationary scale table 38 constitute receiving and stacking stations for the sheets of wood pulp arriving in rows from a lpulp forming machine.

The scale table 38, mounted on the depressed end 39 of the platform 1S, supports the stack 40 of sheets, there established, on a number of rollers 41. These are normally stationary, but are rotated by a motor drive to transfer the stack to a following conveyor as soon as the stack reaches its desired final weight The carriage 23 is shiftable between the position shown in the drawing, where the scale table provides the lowest step of the stair arrangement including the carriage, and a position wherein the lowest step of the carrage, on a tongue extension -45 thereof, projects above the scale table .38. This shifting motion is obtained through the driving action of an air cylinder 42 which is lixed to one of the beams .20. The piston rod 44 extending from the cylinder is connected with the carriage 23 by bracket 46.

Along the side of the platform 18 that is adjacent to the posts is an elongated structural element 50 which has an upper contour following, but slightly below that of the carriage 23. This element 50 is vertically movable, only, and is guided in this movement through the straddling engagement of the legs S2, rigidly depending therefrom, with the grooved pulleys 54; The pairs of legs 52 are joined at :their bottom ends by the connectors 56. The latter are attached piston rods 58 of suitable motivating cylinders. p

From the upper wall .60. of :element .50 extends three horizontal pins v62 at each step level'. These .reach between but a triebelow the pins 34 extending from the opposite wall of casing 30. In the same manner the end portion 43 of element50l carries a number of pins 64 which project between the rollers 41 ofthe scale table 38. shaped cross sections so that 'the .narrow upright portions of the T-shape .occupy a minimum space between ystacks .from .the :scale .table .3.8. The extent Aof the loadactuated downward movementv of the scale platform is relayed through a rod 70 to the weight registering dial 72 mounted on the cross member 16.

A feeding device 74 deposits the sheets, arriving from the pulp forming equipment upon the pins 34 and rollers 41. This ldeviceconsists of a series of upper and lower endless belts 76 and 78, which run between two sets, 80 and .82, of paired axles. The upper .and lower axles forming the pair 80 are vheld in bearings mounted in posts 10, and the other'axle pair 82 are supported in the outer ends of swingable arms 84 The arms '84 aresecured at their -inner ends to studs 86 extending from'links 88. These links are connected at Atheir upper ends with piston rods 90 of cylinders 92.

By this arrangement it is possible to regulate the angle lower belts.

These pins 64 .have in this example. T-' f Beneath the feeding device 74, and parallel to the axles and 82, thereis a rotatable shaft 102. ln each end of this shaft there is a gear 104 which rides upon a horizontal rack 106. Each of the racks is supported upon a .holder 108. Along the outer sides of the racks 106 are mounted runway strips 110 for the wheels 112. Upper strips 116 suspended from holders 118, form thel upper portion of the runways. Bearings 120, for the wheels 112, are located in connector plates 122. The other ends .of .the plates are ported to receive the axle 102.

This assembly, including plates 122, wheels 112 and gears 104, provides a carrier for axle 102. The carrier is reciprocated throughthe connection of piston rod 124 with the axle v102. Fluid within cylinder 126 motivates the piston rod. Projecting from the axle 102 are slats 128 which, on forward movement of the axle, are interposed above the stacks 40 in the path of the sheets discharged from the feeding device 74.

Marking the division lines between the stepped receiving stations are V-shaped members 130 which serve to keep the rows ofsheets in alignment as they issue from .the belts of feeding device 74. Cooperating with members 130 are stack dividers 132 which extend down .between the steps 36 and act as lateral guides for the sheets accumulating in stacks 40. These dividers are all carried by a .transverse holding bar 134, which is raisable through a .connection with chain 136.- The dividers Yare vibratedto improve their'aligning function by a pneumatic vibrator 13S. f

On the feede-r side of the stacks 40 there are vertical plates which are Vfastened to arms 142V through which the plates are given a vibrating movement. The vibrating action is developed through linkage arrangements V144 which depend from end posts il? and the eccentric connection at146 Aof arms 142 to rotating discs When it is desired to first operate the apparatus, it should be in the position shown in Figure l. A number of partial `stacks 40 are placed on the steps 36 of the carriage 23 and the scaletable 38. The height of the stacks, l'thus manually formed, may be the same as indicatedr in the drawing, but the stack on the scale table must in any case weigh less than the preselected linal weight of a completed stack.

With the preliminary stacks arranged, the feeding of the sheets from the feeding device 74 is initiated. The `falling sheets abut .stop members .150, and under the ipnuence of the vibrating dividers 132 and plates 140 drop in concise alignment upon the stacks.

v When -thestack 40 on the scale table 38 has reached the predetermined weight, such as 500 pounds, delivery of the sheets is immediately interrupted by intervention of slats 128. The automatic control devices which effect the uid propelled movement of axle 102, upon which the slats 128 are carried, and which bring about the actuation of other mechanisms of the apparatus, are not shown in detail herein as they are generally conventional in design and are not considered essential features of this invention.

The prime component of the control system isa sensing member, such as a photo cell or induction element, adjustably positioned on the edge of the scale dial 72 and set to report the arrival of the dial needle at the figure representing the selected final weight of the stacks.

The electrical signal thus generated is electronically amplified and transferred through suitable relays and timing devices to solenoids and switches controlling the flow of air, hydraulic liquids, and electricity to the various driving means. The reactions to the electronic signal are practically instantaneous for some purposes and with momentary timed delays for other functions.

The immediate projection of the slats 128 in response to the signal is accompanied by the simultaneous raising of the divider plates 132. Promptly thereafter rollers 41 are motor rotated to transfer the stack of full weight from the scale table 38 to the compression and baling conveyor 66. At the same time, carriage 23 is propelled one row distance to the right as viewed in Figure l bringing the tongue extension 43 above the scale table and each other stack station one full step in the same direction.

As soon as the carriage reaches its new position, element 50 is forced upwardly and the four remaining partial stacks are raised, by pins 62 and 64 of the element, above and clear of the pins 34 extending laterally from the casing wall of the carriage. The carriage is then immediately returned to its original position. iust after its arrival there element 50 drops down to turn the support of the stacks back to pins 34 of the carriage and to the now stationary rollers 41 of the scale table.

Attending the shifting of the load of the stacks back to the carriage, dividers 132 descend and the normal flow of sheets from the feeding device i4 is resumed. The sheets that have meanwhile accumulated on slats 12S drop into place, being held above the stacking stations by plates 140 as the slats E28 are withdrawn from the projection between these plates.

Sheets are again continuously fed to the five stations until the stack on the scale reaches the desired weight and the effect of the indicating needle upon the photo cell or induction unit terminates this next stacking cycle by motivating the various relays, switches and solenoid valves. The stack now built to the exact weight desired is discharged from the weighing scale station for pressing and baling and the other partially built up stacks are shifted over to the adjacent stations.

There are roughly about 500 sheets in each completed bale. By the automatic weighing provided by the apparatus of this invention, variation in weight of the bales does not exceed that of a single sheet. Accordingly maximum overweight is restricted to approximately one pound or one fifth of one percent of the full bale weight, with the average one half of that amount. This is a reduction of some ninety percent of the surplus sheets included in the bales by the previous hand methods and cuts the monetary loss in the same proportion.

It may be observed that the apparatus of the invention also accomplishes the previously mentioned objects of producing bales of uniform size, and uniform pulp and water content.

Important among the features of the invention responsible for the attainment of the objects are the means for building up stacks in graduated sizes crosswise of the delivery end of a pulp machine upon the stepped carriage,

utilizing a proportional quantity of sheets from each row for each final stack, automatically terminating the stacking momentarily when the largest stack reaches the desired weight, removing such stack, shifting the remaining partially built-up stacks and resuming the receipt of sheets from the associated pulp machine.

A special feature of the invention is the stairway arrangement which minimizes the distance the sheets drop to reach the stacks and thus makes alignment more accurate and the resulting stacks more smoothly contoured. Of supplemental importance are the means of shifting the stacks and retaining them in new positions with the return of the carriage to its original location.

The particular apparatus disclosed herein is for illustration only as it is realized that Various other types of conveyors, controls and mechanical elements may be utilized in creating an apparatus embodying the features and spirit of this invention. For example, the carriage 23 would perform fairly satisfactorily with one or two of its steps including two receiving stations instead of having a descending step for each station.

Accordingly, the appended claims should be interpreted sufficiently broadly to encompass any such obvious modifications or substitutes except where the language thereof is definitely specific to disclosed elements.

We claim:

1. Apparatus for receiving and stack forming similarly dimensioned sheets of wood pulp produced in a pulp machine including delivery means discharging sheets of Wood pulp in adjacent rows, a reciprocable carriage positioned transversely of the discharge end of the delivery means, a normal first position and a temporary second position for the carriage, the first position and the second position being the common width of a row of sheets apart, said carriage having a series of sheet receiving stations in descending stepped formation with each station dimensioned and arranged to receive and form a stack of the sheets delivered in a particular row when the carriage is in its first position, means for momentarily moving the carriage transversely of the discharge end of the delivery means from the first position to the second position after a stack of sheets has been collected in each station whereby each station with a stack of sheets is moved beyond the path of the particular row of sheets received thereon in the first position, means raising and retaining the stacks of sheets carried by the stations while the carriage is in the second position and returning the carriage, while the stacks of the sheets are raised, back to the first position, and means for lowering the retained stacks of sheets upon the new stations thus brought beneath them.

2. An apparatus according to claim 1 in which there is an extra receiving station for a row of sheets, adjacent the lowest station on the carriage when the latter is in its first position', upon which the stack of sheets collected in the lowest station on the carriage and raised therefrom when the carriage is moved to the second position is lowered when the carriage is returned to the rst position.

3. An apparatus according to claim 2 in which a weighing scale is associated with the extra receiving station and therev are means actuated by the registration of a preselected weight by the weighing scale for removing the stack of sheets from the extra receiving station and for reciprocating the carriage. A

4. Apparatus according to claiml in which the means raising and retaining stacks of sheets comprise horizontal fingers and vertical slidable mountings for the fingers by which the lingers are raised through slots in the stations.

References Cited in the file of this patent UNITED STATES PATENTS 2,205,767 Lamb June 2S, 1940 2,496,438 Brandt Feb. 7, 1950 2,704,593 Galloway Mar. 22, 1955 2,822,932 Patrick Feb. l1, 1958 2,831,585 Patrick Apr. 22, 1958

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