US3025057A

US3025057A - Continuous layboy

Info

Publication number: US3025057A
Application number: US37423A
Authority: US
Inventors: Dale Ingvald; Gile A Mead
Original assignee: Lamb Grays Harbor Co
Current assignee: Lamb Grays Harbor Co
Priority date: 1960-06-20
Filing date: 1960-06-20
Publication date: 1962-03-13
Anticipated expiration: 1979-03-13

Description

March 13, 1962 l. DALE ETAL 3,025,057

CONTINUOUS LAYBOY Filed June 20, 1960 7 SheetsSheet 1 m I w x l 2 33232:: I l I. I I

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CONTINUOUS LAYBOY Filed June 20, 1960 7 Sheets-Sheet 3 TOENEYS March 13, 1962 l. DALE ETAL 3,025,057

CONTINUOUS LAYBOY Filed June 20, 1960 7 Sheets-Sheet 4 INVENTOR. lueunw DALE K [LE A.MEHD

' ATTORNEYS March 13, 1962 DALE ETAL CONTINUOUS LAYBOY 7 Sheets-Sheet s Filed June 20, 1960 HLE E INV HLD jLE A m flTTo ENE rs March 13, 1962 1. DALE ETAL 3,025,057

CONTINUOUS LAYBOY Filed June 20, 1960 7 Sheets-Sheet 6 .LJ l 1 ING VHLD g ZZ E G/LE A MEAD March 13, 1962 l. DALE ETAL 3,025,057

CONTINUOUS LAYBOY Filed June 20, 1960 7 Sheets-Sheet '7 INVENET 0R.

NGVHLD 04 flTTOR NE 75 3,625,057 Patented Mar. 13, 1962 Free Filed June 20, 196i Ser. No. 37,423 Claims. (Cl. 271-68) This invention relates to improvements in layboys as used by the paper making industry for the stacking of paper sheets as discharged from the paper cutting machines.

It is the principal object of this invention to provide a novel and practical mechanism for continuously stacking sheets of paper, as successively delivered into a stacking bin from the cutting machine, in conjunction with means for transferring stacks of paper sheets of predetermined count from the base or lower portion of a continuously forming stack without interruption in the paper cutting or sheet stacking operations.

It is a further object of the present invention to provide an improved mechanism of the kind above stated, embodying therein, in conjunction with sheet stacking bins and stacking tables on which the stacks are formed, novel means for effecting separation of lower and upper portions of the forming stack preparatory to the removal of the base or lower portion of predetermined count, and novel means for giving temporary support to the upper or continuously forming portion of the stack while said lower portion is being removed by the table and until the table has been returned to stack supporting position.

Another object of the invention is to effect temporary support of the upper portion of the forming stack while the lower portion is being removed, by a novel arrangement and use of certain devices including a series of belts that are drawn into and from stack supporting position with the travel of the stacking table to and from discharge position to receive thereon and support the forming portion of the stack while that portion of predetermined count is being removed and to do this without any sliding or frictional movement between the belts and the supported stack that might result in misalignment or disturbance of sheets in the forming stack.

Yet another object of the present invention resides in the specific devices employed for effecting the separation of the formed stack or predetermined count from the upper portion of the forming stack, and in their relationship to and use in conjunction with the stacking bins and stacking tables of the machine.

Still further objects and advantages of the present invention reside in the details of construction and combination of parts and in their mode of operation, as will hereinafter be fully described.

In accomplishing the above mentioned and other objects of the invention, we have provided the improved details of construction, the preferred forms of which are illustrated in the accompanying drawings, wherein:

FIG. 1 is a plan, or top view, of a layboy embodying the improvements of the present invention therein, in readiness to receive paper sheets from a paper cutting machine, for continuous stacking.

FIG. 2 is a vertical section taken lengthwise of the machine on line 2-2 in FIG. 1; showing a stack being formed on a stacking table.

FIG. 3 is a fragmental side elevation of parts of the present machine, showing in larger scale, the forming of a stack therein.

FIG. 4 is a fragmental side elevation, illustrating the removal, by the table, of the lower divisional portion of a forming stack from the stacking bin of the machine.

FIG. 5 is a fragmental elevation showing the stack of predetermined count after being moved by the table to the discharge or unloading position and showing the sheets of the continuously forming stack as temporarily supported in the stacking bin by the stack dividers and the series of belts.

FIG. 6 is a side view illustrating the stacking table dur ing its return travel to initial position for the support thereon of the continuously forming stack.

FIG. 7 is a vertical section, taken through the backstop Wall of the stacking bin, showing a stack dividing shoe and its actuating solenoid mounted on the forward face thereof.

FIG. 8 is a vertical, sectional detail, showing the level and disposition of the stack dividing fingers at the rearward or receiving end of the sheet stacking bin.

FIG. 9 is an underside view of a stacking table.

FIG. 10 is a side view of the stacking table.

FIG. 11 is a sectional detail at the receiving end of the machine showing the stack dividing fingers and shoes as associated with the stacking bin and table.

FIG. 12 is an enlarged, cross-sectional, detail showing the means of connecting one of the stack supporting belts under spring tension with a transverse frame member.

FIG. 13 is an enlarged cross-sectional detail, taken on line 13-13 in FIG. 2, showing the air cylinder support and actuating means for the cross-beam that carries the stack dividing shoes.

FIG. 14 is a schematic layout of the electrical system employed for control of the various devices employed in the operation of the present machine.

In the following description, the forward end of the machine will be that which is at the right hand end in FIG. 2, while the rearward end will be that at the left hand end of FIG. 2. This same designation applies to the stacking bin and parts associated therewith.

Referring more in detail to the drawings and particularly to FIGS. 1 to 6 inclusive; it is to be understood that paper sheets, as designated by numeral 10 in FIGS. 3 to 6, are successively and rapidly infed to the present stacking mechanism from a paper cutter, not herein shown but which would ordinarily be located adjacent the left' hand end of the machine, as seen in FIG. 2; the paper sheets 10 being delivered to the stacking bins on or between traveling belts of a conveyor system designated generally in FIG. 2, by reference numeral 11.

On entering the machine, the sheets 10, as shown in FIG. 2, to pass between paired feed rolls .12 and 13 and are delivered horizontally therefrom into a stacking bin, B, against a back stop 14 and are dropped onto a stacking table, as at 15, to form a stack, such as that designated at 16.

A sheet stacking mechanism of the present kind usually comprises a succession of stacking bins, side by side, each equipped at forward and rearward ends with stack separating shoes and fingers. In the machine, as shown in FIG. 1, there are two stacking bins. However, since each bin is like the other and has a table and similar equipment associated therewith, the following description of the one as shown in FIG. 2 will likewise apply to all others that may be employed in the machine.

The stacking table on which the paper sheets are re ceived, as dropped into the bin to form a stack, is caused to be gradually lowered, from a predetermined upper limit of adjustment, in accordance with the rate of increase in height of the stack thus to keep its top surface at the same level. After the stack, as formed on the gradually lowering table, has reached a predetermined count, the stack dividers of this invention later described, are actuated into positions overlying and pressing down wardly against the forward and rearward top edge portions thereof. The stacking table is then lowered sufiiciently to clear the top of the stack of predetermined count from the lower edge of the back stop of the stacking bin and the table is then advanced. The stack is thereby moved below and forwardly of the back stop, to a position for its lateral unloading or discharge for its conveyance from the machine.

Upon the removal of the stack of predetermined count from the stacking table, the table is automatically raised to its upper level and is returned to loading position for the support thereon of the continuously forming stack. With the full return of the table to stack supporting position, the temporary stack dividing fingers and shoes are returned to their original or retracted positions and stacking of infed sheets continues without interruption.

The stacking bin B, as seen in FIGS, 1 and 2, is bounded at its forward end by the vertical back stop 14; at its opposite or rearward end by a substantially vertical, pivotally suspended jogging wall plate 17 and at its opposite sides by stack separator plates or division walls 1818. The stacking table, 15, onto which the sheets drop from the back stop to form the stack ordinarily constitutes the bottom of the stacking him, as will be understood by reference to the showing of its position in FIGS. 2 and 3. It is shown in FIGS. 1 and 2 that the stack separators or sidewalls 18-18 of the stacking bin are supported from and below a transverse frame member 20 with their lower edges substantially at the same horizontal level of the lower edge of the back stop 14.

The back stop 14, as best shown in FIG. 7, comprises a vertical plate, disposed transversely of the machine. This is supported by a horizontal and transversely directed frame beam 24. It is shown in FIG. 1 that the beam 24 is supported at its opposite ends by horizontal frame rails 25-25, that extend lengthwise of the machine along opposite sides thereof, for its adjustment vertically and also in a direction lengthwise of the machine to accomodate stacks of different height and length.

Located adjacent what has herein been designated as the forward face of the back stop 14, as best shown in FIG. 7, are the stack separation shoes 26. These are suspended in laterally spaced relationship, at predetermined intervals of spacing along the back stop from an angle iron cross-beam 28. This cross-beam 28 is supported at intervals therealong by brackets 29, each of which is rigidly fixed to and extends forwardly from a mounting plate 30. Each plate 30 is parallel to the backstop and is slidably contained, at is opposite side edges, in channel-like guideways 31 that are fixed vertically to the forward face of the back stop. The crossbeam 28, and parts mounted thereby are supported in operative positions relative to the backstop by an air cylinder 32 which, as shown in FIG. 7, is fixed vertically to the cross-beam 24 of the frame structure of the machine. A piston rod 32' extends downwardly from the air cylinder to support the beam and the condition of the cylinder is normally such as to hold the cross-beam 28 and shoes as mounted thereby in elevated position, as indicated by the full line showing of these parts in FIG. 7. Upon fully exhausting air from the cylinder 32, the cross-beam 28 will drop to its lower level, as in dash lines in FIG. 7 for the purpose of engaging the toe ends of the shoes against the stack, as will presently be explained.

Each of the stack dividing shoes comprises a fiat, horizontally disposed plate that is beveled to a thin horizontal edge at its rearward or toe end. A longitudinal rib or flange 26f is formed centrally on the top of each shoe and each shoe is supported for limited forward and rearward swinging movement by a forward pair 34 and a rearward pair 34' of suspending links, which pairs of links are fixed, respectively, at their upper ends to horizontal shafts 3535 that are extended through and rotatably mounted by the bracket l Associated with the links 34-34' of each of the swingingly suspended shoes 26 and fixed above the level of beam 28, to the vertically adjustable plate 30 is a solenoid 36. The solenoid 36 has a horizontal sliding core bar 36 with a pin and slot connection 37 at its extended forward end with the upper end of a lever arm 37 that is fixed, at its lower end, to the cross-shaft 35. Energization of the solenoid 36 causes the core bar 36' to be retracted and to thereby effect the forward swinging of the lifted shoe from stack engaging position to retracted position, as shown in dash lines in FIG. 7, at 26r.

The stack separating fingers 40, located at the rearward end of the stacking bins, as seen best in FIG. 8, are slidably mounted for endwise retraction and extension beneath a plate 42 across which the paper sheets 10 are delivered from the paper cutter into the bin B. These fingers are laterally spaced, in accordance with the spacing of the shoes at the other end of the bin, or as may be desired. At their rearward ends, the fingers are fixed to a horizontal cross-bar 44 for their extension and retraction in unison; the bar 44 being extended transversely of the bin and adapted to be actuated forwardly and rearwardly by connections at its ends with the upper ends of rocker levers 45, that are pivoted between their ends, on a cross-shaft 46 for actuation by a connecting rod 47 which, in turn, has operative connection, as has been shown in FIGS. 8 and 11, with the piston of a horizontally fixed air cylinder 48. Normally the fingers 40 are retracted as seen in full lines in FIG. 8 and are moved into their extended or functional positions simultaneously, with the dropping of the shoes 26 against the stack, as will presently be explained.

The table shown enlarged in FIG. 10, on which the paper sheets are stacked, as they are successively received in the stacking bin, comprises a horizontal top 50 supported at each of its opposite sides by a pair of crossed and pivotally joined

levers

51 and 52; the pivotal connection comprises a cross-shaft 53 that is common to both sets of levers. It is further to be observed in FIG. 10, that the crossed levers of each pair are pivotally fastened, respectively, at their rearward ends, as at 53f, to the table top and to a base or carrier frame 54; the carrier being equipped with wheels 55 mounted for rolling travel on a horizontal trackway 56 formed with the base structure of the machine frame. At their forward ends, the levers have horizontal sliding connections with the stacking table and carrier frame, respectively, as at 66 in FIGS. 3 to 6. This permits a scissors-like action of the levers for the raising and lowering of the table top for the intended purposes.

Located between the top 50 and carrier frame 54 of the stacking table, is a fluid pressure medium cylinder 67 supported from the cross-beam 53 that extends between the two sets of paired levers 51-52. A piston 67' with piston rod 671* extends rearwardly from the cylinder and is fixed at its end in a cross-head 6711 which mounts paired rollers 63 at its opposite ends that are disposed between the diverging rearward ends of the crossed levers, as seen in FIG. 9, for rolling travel on cam surfaces of these levers. As the piston rod is extended and retracted, the action of the crossed levers causes lowering and raising of the table top accordingly. Pressure medium for the cylinder is supplied thereto under valve and pump control through pipe lines 69 and 63 that are attached to its forward and rearward ends. This medium may be metered by various means to the cylinder 67 under control of a sheet counter, or the like, to cause table lowering at the required rate to maintain the predetermined top level of the stack as it forms in the bin.

It. has been indicated in schematic view of FIG. 14 that a limit switch LS1 is actuated by a cam m or a rotary knife driving shaft S. This switch gives an electrical impulse to a sheet counter C for each sheet delivered into the bin.

It is further schematically indicated that a time delay relay 82 which, after a predetermined interval, actuates a control valve 67 for the cylinder 67 which causes the table to be lowered to down position for unloading travel. Further explanation will be given later in describing the mode of operation.

Supplementing the shoes 26 and the fingers 40 as actuated to functional position, for the support of a forming stack while the formed stack of predetermined count is being moved to discharge position by the stacking table, is a plurality of narrow belts 74 that have ends fixed to the frame structure, as at 71 in FIG. 8, to extend forwardly as shown in FIG. 1. Each belt extends horizontally, passing forwardly over a roller 72 mounted between the upper ends of brackets 73 that are rigidly fixed, as well shown in FIGS. 3 to 6 to and extend upwardly from the rearward end of the carriage or base structure 54 of the table. After passing forwardly and over roller 72 the belts are directed downwardly to a level below the table trackway passing about a transverse roller 74 that moves with the table carriage then forwardly and are attached, each under spring tension, as best shown at 70' in FIG. 12 to a cross-beam 75 that is fixed horizontally in the frame structure below the unloading station. Thus, as the table moves forwardly, the plurality of belts 70 are drawn across the bottom of the sheet stacking bin, to support the sheets as delivered across the extended fingers against the back stop; this method of support of the forming stack during an unloading operation as illustrated in FIGS. 4, and 6. With return of the table from unloading to stack receiving position, the

rollers

72 and 74 pass the belts thereover without causing any relative movement of the forming stack and the supporting portions of the belts as extended between the roller 72 and their anchored ends. The springs 70 maintain stack supporting tension on the belts at all times.

It is an important feature of this invention that the belt 70 is supported at the level of the top of the formed stack and just slightly below the level of the fingers 40. When the stacking table moves forwardly, in the removal of the formed portion of the stack the belts 70 maintain their elevation and are drawn taut immediately below the forming stack as then supported on the extended fingers and shoes, as will be understood by reference to FIG. 5. The forming stack is thus supported on the belts during the removal of the stack of predetermined count and until the stacking table is returned to initial position. In a present operation, the belts 70 are spaced approximately three inches apart. The feature of their use is that there is no relative movement at any time between contacting portions of belts and supported stack and their tension maintains the stack as supported thereon against sagging.

The stacking table, as mounted on its base or carriage structure, is reciprocally actuated, for the removal of the stacks of predetermined count from the bin to the stack unloading or discharge station and its return to initial position, by means of an electric motor 75, referred to herein as the table motor which is mounted in the frame structure at its sheet receiving end as shown in FIG. 2. This motor operates through a belt connection 76, to drive a continuous chain belt 77 that is extended horizontally of the machine, beneath the table, passing about supporting sprocket wheels 78 78'. A link 79 is pivotally connected at its ends as at 8080 to a link of the chain belt '77 and to the table. Thus, with the driving of the chain belt 77, the table will be caused to be reciprocally moved upon the trackway 56, between stack receiving and stack discharge stations. Normally the motor 75 is inactive and the stacking table is located thereby at the stacking station, as seen in FIG. 2.

The top structure of the stacking table has incorporated therein the teaching of US. Patent No. 2,785,928, issued March 19, 1957 to Victor E. Hanson, in its top surface structure. This consists of the provision of a multiplicity of air valves therein that are caused to be opened under the weight of a stack resting thereon to permit the escape of air under pressure from an air storage chamber beneath the surface to the underside of the bale to facilitate its sliding removal from the stacking table.

It is anticipated that the top surface structure of the table top onto which the stacks are unloaded shall likewise be equipped with valves and an underlying chamber for air under pressure. The means for controlling the use of these air valves will be later disclosed.

The electrical wiring and the various controlled means shown in connection therewith, in FIG. 14, will be described in connection with the following explanation of the mode of operation of the machine. 1

Assuming that the present sheet stacking mechanism has been constructed as illustrated and described and that the stacking table has been properly positioned to receive and support sheets 18 as delivered from the paper cutter into the stacking bin, and that the stack dividing shoes 26 have been lifted to raised positions as in FIGS. 3 and 7 and the fingers 40 retracted, its operation would be as follows:

Sheets of paper 10 are delivered in rapid succession by the infeed means 11 against the lower edge portion of back stop 14 and drop therefrom into the stacking bin. As the stack builds up on the table top 50, the latter is lowered accordingly, as required to maintain the top surface of the stack at a predetermined level; the downward movement of the table being controlled by the sheet counter, as previously explained, which operates in conjunction with the rotary knife of the paper cutter.

After a predetermined number of sheets have been cut and delivered, the counter actuates the control valve of air cylinder 48 which effects extension of the stack dividing fingers 40 over the rearward top edge surface of the forming stack and at the same time similarly causes the air cylinder 32 to drop the beam 28 and cause the extended rearward ends of the shoes 26 to drop against the top of the forward edge of the stack. This causes incoming sheets 10 dropped into the bin to then be received at their rear and forward edges upon the fingers and shoes which now function as stack dividers or separators as indicatedin FIG. 4.

The counter also is electrically connected with and actuates the time delay relay 82 which, after a pre-set time interval, actuates the hydraulic cylinder 67 to lower the table 15 to its down position as in FIG. 4 for forward advancement or movement of the stack thereon, beneath the lower edge of back stop 14 to the unloading station in which it is shown in FIG. 5.

The down travel of the stacking table is. stopped by the engagement of a stop 85 fixed thereto, with a limit switch LS2, which incident thereto energizes the electric motor 75 to move the table forwardly and away from the stacking position to the discharge station; the table travel being stopped by its contacting and actuating a limit switch LS3 which is incorporated in the control system of motor 75. This limit switch LS3 serves two additional purposes: First, it serves to start a blower motor 86 to supply air to the table top 50 and also to energize the pusher motor 87 which is operable to actuate a pusher bar 88 to push the stack of predetermined count laterally from the table top onto a receiving table 89.. The pusher bar 88 is shown at the top, right hand end of FIGS. 2 and 3 and the receiving table 89 is indicated at the lower right hand end of FIG. 1. The pusher bar movement is stopped by its contacting a limit switch LS4 which causes the hydraulic cylinder 67 to raise the table; its upward movement being stopped by a limit switch LS5 which also energized the table motor 75 to move the raised table back to starting position, to be stopped by its contact with a limit switch LS6.

Limit switch LS6 also operates to stop the blower motor 86 and energizes the solenoids 36 to retract the extended shoes 26 and start the pusher motor 87 to return the pusher bar to retracted position. When the shoes 26 move into fully retracted position, they actuate a limit switch LS7 which energizes the air cylinder 32 to raise the cross-beam 28 and the shoes mounted thereon above the stack level. As the shoes raise, they actuate a limit switch LS8 which energizes solenoids 36 to extend the shoes, as in FIGS. 2 and 7, in readiness for dropping against the stack in the next stack dividing operation. Adjustment in positions of the various limit switches may be made to suit the work being done.

By the means above described, the continuous stacking of sheets is possible and stacks of predetermined number of sheets or height may be removed from a forming stack without interruption in the paper cutter or means for feeding of sheets to the stacking bins. The various parts of the machine may be easily and readily adjusted to accommodate sheets of various dimensions.

What we claim as new is:

1. A continuous layboy mechanism for use in combination with a delivery mechanism for the continuous delivery and stacking of sheet material; said layboy mechanism comprising a stacking bin, a back stop member against which the sheets engage in the formation of the stack, a movable stacking table normally positioned to serve as a bottom for said stacking bin for the support thereon of the continuously forming stack, stack dividing means movable from normally non-functional position to a position for effecting the dividing of a lower portion of a forming stack from the upper portion thereof, means for moving said dividing means to dividing position, means for moving said table from its normal position for the conveyance of the lower divisional portion of the stack thereon to a discharge station, a temporary stack supporting means that is caused to be progressively positioned, with the movement of said table toward the dis:- charge station, to serve as a temporary suppont for the upper divisional portion of the forming stack while the stacking table is out of its normal stack supporting position, said temporary stack supporting means including a stack supporting belt, means on said stacking table for progressively supporting said belt in stack supporting position in and across the area of normal position of said stacking table incident to the movement of said stacking table to said discharge station, means for returning said stacking table to normal position, means for causing said belt to be progressively removed from stack supporting position with the return of the stacking table to normal position, and means for causing the return of said stack dividing means to non-functional position with the return movement of the stacking table,

2. The combination recited in claim. 1 wherein said back stop is in fixed position and said stack dividing means are located at the forward and rearward ends of the stacking bin and wherein the stacking table is caused to be lowered by means that is operated by and in accordance with the delivery of sheets from the delivery mechanism.

3. The combination recited in claim 2 including means for causing an additional lowering of thetable after division of the stack to clear the top of the lower divisional portion thereof from th lower edge of said backstop preparatory to the movement of the lower divisional portion to the discharge station.

4. The combination recited in claim 1 wherein said belt supporting means includes an upper roller mounted on the rearward end of said stacking table and wherein said belt is secured at one end to and below said delivery mechanism, av lower roller secured to and below said stacking table and below said upper roller, said belt extending over said upper roll and below said lower roller and the other end of said belt being secured below said stacking table.

5. In a continuous layboy mechanism of the character described; a sheet stacking bin having a transversely disposed vertical back stop fixedly supported at its forward end, a sheet delivery mechanism, a movable table normally positioned to serve as a bottom for said bin for the stacking of said sheets thereon, a plurality of fingers mounted beneath said delivery mechanism at the rearward end of the bin, a plurality of sheet supporting shoes mounted by said back stop, means mounting said shoes whereby said shoes are downwardly and rearwardly movable from a retracted position above the formed stack to an extended position over said stack and means for simultaneously dropping said shoes onto the top surface of the formed stack whereby the shoes receive and sup port the next incoming sheet, means for extending and retracting said fingers from a normally retracted position to an extended position across the adjacent top edge of a formed stack, means for moving the table to convey the lower divisional portion of the stack to an unloading station and for return of the table to normal position after unloading.

6. The combination recited in claim 5 wherein said stack supporting shoes are disposed at a level that is slightly above the lower edge of the back stop and said back stop is formed across its lower edge portion with notches that receive the shoes therethrough in their rearward and downward swinging action for stack division.

7. The combination recited in claim 1 wherein said stacking table includes an air chamber below the upper surface thereof and a plurality of air release valves mounted in and projecting above the upper surface of said stacking table.

8. The combination as recited in claim 1 including means operating in accordance with rate of delivery of sheets onto the forming stack for effecting lowering of the stacking table in accordance with rate of increase in height of the stack, thus to maintain the top surface of the stack at a constant level above the lower edge of the back stop.

9. The combination recited in claim 5 including also, a sheet counter that is actuated by and in accordance with delivery of paper sheets into the bin for stacking and wherein the adjustment of said fingers and said shoes from retracted to stack dividing positions is cont-rolled by said counter and their retraction is controlled in accordance with movement of the stacking table to normal position after unloading,

10. The combination recited in claim 9 including means for supporting said shoes for vertical adjustment on the back stop, an actuating solenoid for each shoe and means controlled by the sheet counting means for energizing the solenoids to simultaneously extend and retract said shoes, and a movable support controlled by the stack counting means for simultaneously lowering all shoes as extended, against the top of the forming stack.

References Cited in the file of this patent UNITED STATES PATENTS 1,938,325 English et al Dec. 5, 1933 2,205,767 Lamb Jan. 25, 1940 2,228,887 Peterson Ian. 14, 1941 2,675,747 Greiner et al. Apr. 20, 1954