US3301377A

US3301377A - Sequence unloader

Info

Publication number: US3301377A
Application number: US510544A
Authority: US
Inventors: Charles L Larson
Original assignee: Jeddeloh Bros Sweed Mills Inc
Current assignee: Jeddeloh Bros Sweed Mills Inc
Priority date: 1965-11-30
Filing date: 1965-11-30
Publication date: 1967-01-31
Anticipated expiration: 1984-01-31

Description

SEQUENCE UNLOADER 2 Sheets-Sheet 1 Filed Nov. 30, 1965 C'hczrlesL. Larson BY INVENTOR dj, //4/LZ2Z Jan. 31, 1967 c. L. LARSON 3,301,377

S EQUENCE UNLOADER Filed Nov. 30, 1965 2 Sheets-Sheet 2 United States Patent SEQUENCE UNLOADER Charles L. Larson, Grants Pass, 0reg., assignor to Jeddeloh Bros. Sweed Mills, Inc., Gold Hill, Oreg., a corporation of Oregon Filed Nov. 30, 1965, Ser. No. 510,544 5 Claims. (Cl. 198-32) This invention relates to an unloader for unloading the various decks of a multiple-deck sheet-handling conveyer. More particularly, it relates to novel means for controlling the discharge of sheets from various receiving stations provided in the unloader.

The unloader of the invention may typically be employed in unloading sheets of veneer from the various decks of a multiple-deck dryer, and discharging these sheets onto an otfbearing conveyer in an orderly fashion, whereby the sheets may be graded, sorted and otherwise processed.

A conventional veneer dryer may be provided with five or six decks, and successive charges of sheets, each containing usually a multiple number of sheets, travel through the dryer on each deck while being heated for the purpose of being dried. An unloader at the offbearing end of the dryer receives charges of sheets from the various decks, and for each charge it must wait until it has received all the sheets in the particular charge before shifting the sheets onto any conveyer, or serious problems of misalignment and skewing of the sheets result. the unloader on receiving a charge of sheets should discharge the same promptly, to clear itself for a succeeding charge. Further, some provision must be made to prevent charges from two decks leaving the unloader simultaneously with piling up and disarrangement of the sheets in the charges.

Charges of sheets on traveling through a dryer on different decks tend to travel at somewhat different speeds, and an unloader which unloads the various decks of a dryer according to a timing related to the time at which the various decks were fed sheets has serious disadvantages. Furthermore, it is presently common practice to feed the various decks in a dryer with charges where the sheets in the charges fed onto one deck have a length different from the length of sheets in the charges fed another. In this organization, the sequence with which charges of sheets clear different decks at the oifbearing end of a dryer has little relation to the sequence with which charges are fed different decks at the feed end of the dryer.

A general object of the present invention is to provide an unloader for a multideck conveyer operable to receive charges of sheets and to discharge them onto a receiving means, such as a conveyer, with discharge being controlled whereby only one charge at a time leaves the unloader.

A related object is to provide such an unloader, where the sequence in which charges of sheets are discharged from the unloader is independent of any specific sequence in which the various decks are fed successive charges of sheets.

Specifically, this invention contemplates as an object thereof the provision of an unloader with stations for receiving charges of sheets from the various decks of a multiple-deck conveyer which unloader has means interrelating the operation of discharging means in the stations whereby the sequence of discharge is determined by the sequence in which respective stations receive charges of sheets.

' According to this invention, and in the specific embodiments herein disclosed, charges of sheets from the various decks of a multideck conveyer have their movement accelerated on leaving the end of the multideck conveyer, whereby a spacing between each charge and the charge on the deck succeeding it is produced. Preferably then the ends of the various sheets in a charge are aligned.

On the other hand,

"ice

Means is provided for each deck for detecting the trailing ends of the sheets of a particular charge. In the eventuality that charges of sheets are traveling from two decks into two stations of the unloader simultaneously, the station which first completely receives a charge of sheets, with the trailing ends of sheets in the charge traveling past a detector in the station, discharges its sheets first, and the other station during this time is prevented from having its discharging means operated. Upon the first-mentioned station having its charge cleared therefrom, the other stations discharging means is made operative, with its charge of sheets then being moved clear of the station. Thus, charges travel from the unloader one at a time, although the unloader may be receiving charges simultaneously. The sequence in which charges are discharged from the unloader has no specific relationship to the sequence in which decks in the multideck conveyer are fed charges.

These and other objects and advantages are attained by the invention, and the same is described hereinbelow in conjunction with the accompanying drawings, wherein:

FIG. 1 is a side elevation of portions of sheet-handling apparatus as contemplated herein, showing at the left of the figure the offbearing end of a veneer dryer, to the right of this dryer an unloader which discharges sheets straight forwardly from the dryer, and to the right of the unloader portions of an offbearing conveyer;

FIG. 2 is a schematic diagram illustrating control circuitry as contemplated by the present invention for controlling the flow of sheets in the unloader shown in FIG. 1;

FIG. 3 is a side elevation of portions of sheet-handling apparatus according to another modification of the invention, showing at the left of the figure the offbearing end of a veneer dryer, and to the right of the dryer portions of an unloader;

FIG. 4 is a view taken along the line 4-4 in FIG. 3, and illustrating at the right of the figure the infeed of an otfbearing conveyer; and

FIG. 5 is a schematic diagram illustrating control circuitry as contemplated by the present invention for controlling the flow of sheets in the unloader shown in FIGS. 3 and 4.

Turning now to the drawings, and with reference first to FIG. 1, what is shown generally at 10 is the offbearing end of a veneer dryer. At 12 is illustrated an unloader adapted to remove veneer sheets from the dryer as they emerge from the end thereof, and at 14 is illustrated an oifbear-ing conveyer or collecting means adapted to collect and carry away sheets discharged from the unloader.

The dryer may have multiple decks, two of which are indicated at 16 and 17. Each of these decks comprises paired rolls, such as rolls 18 shown for deck 16, which follow one another along the length of the dryer, and define a path of travel for sheets of veneer. Typically, veneer sheets are fed into the dryer by a feeder which feeds the decks in the dryer with groupings or charges of sheets, each charge normally comprising from three to six sheets arranged side by side across the deck. The charges of sheets fed into one deck are staggered with respect to the charges fed into the other deck. In a given deck, sheets of substantially uniform length are handled. The sheets are fed into the deck with their leading and trailing edges approximately aligned. However, when the charges arrive at the oifbearing end of the dryer, some misalignment of the sheets is usually present due to various causes.

Unloader 12 is positioned closely adjacent the oifbearing end of the dryer and is adapted to unload successive charges of veneer sheets as these sheets'emerge from dryer decks 16 and 17. For each deck in the dryer the unloader includes conveyer structure for supporting a charge of veneer sheets prior to its being deposited on offbearing conveyer 14 as will now be described.

Considering this conveyer structure for deck 16, at 19 and 20 are a pair of rolls which support a charge during its initial progress from the dryer. Roll 19 may be an idler roll and roll 20 a power-driven roll. Beyond roll 20 is a pair of pinch rolls 21, 22, roll 22 being powerdriven along with roll 20. Beyond pinch rolls 21, 22 are a pair of

opposed rolls

23, 24 which may be idler rolls as shown and another pair of rolls 26, 27 which may be rubber surfaced and support the veneer directly adjacent the ofibearing end of the unloader. Rolls 26, 27 are driven under power intermittently through a chain 28 driven by an intermittently-operated motor 30. Opposed

rolls

23, 24 and rolls 26 and 27 make up what is referred to herein as a receiving station for deck 16 in the dryer, identified generally by the number 31.

Between

rolls

20, 22 is a depending gate or detector 32 pivoted at 33 for movement about a horizontal axis extending transversely of the path of sheets into the unloader. A charge of sheets traveling into the gate causes the base of the gate to swing to one side, the gate returning to its vertical position with the charge completely clearing the gate. Extending upwardly from the gate is an actuating finger 34 operable on swinging of the gate to actuate a switch mechanism 35.

Explaining briefly how the structure thus described operates, on a charge of sheets emerging from deck 16, the charge travels at the speed of the dryer until the lead ends of the sheets in the charge reach the pinch rolls 21, 22.

Roll 22, which normally is rotated at a considerably faster speed than the rolls in the dryer, is then operable on pinching of the charge of sheets to advance the charge- -rapidly from the dryer, to produce a spacing between the charge and the next succeeding charge. The charge travels between

opposed rollers

23, 24 to come to rest on rubber-surface rolls 26, 27 which during this stage of the operation are stationary. The sheets remain resting on these rolls and in the receiving station until such time as motor is energized whence the sheets are propelled forwardly by now rotating rolls 26, 27 to travel onto the ofibearing conveyer 14. Rolls 26, 27 thus function as discharging means for the station in the unloader.

The unloader illustrated includes similar conveyer structure for dryer deck 17. Thus, provided to support the sheets coming from the decks are rolls 19a, 20a. Supporting sheets in the receiving station of the unloader for this deck are rolls 26a, 27a intermittently rotated under power by motor 30a. The receiving station for the deck 17 has been given the reference numeral 36 for general identification. A gate or detector is shown at 37 corresponding to gate 32, which gate through an actuating finger 38 is operable to actuate a switch mechanism shown at 39 corresponding to switch mechanism earlier described.

An unloader similar to the one so far described is illustrated in United States Patent 3,124,233, issued March 10, 1964.

Turning now to FIG. 2, shown generally at 44 is con- 'trol circuitry controlled by

switch mechanisms

35, 39 interrelating operation of

motors

30, 30a as contemplated by the invention. Circuitry 44 includes a first control circuit 46, a second control circuit 48, and a timing circuit 50, operatively connected to and shared by

circuits

46, 48. Circuit 46 includes switch mechanism 35 and controls discharge motor 30 of receiving station 31, and circuit 48 which has many similarities to circuit 46 includes gate switch mechanism 39 and controls discharge motor 30a of receiving station 36. Electrical power is supplied to the various circuits from a suitable source through

power terminals

52, 54, ganged power switches 56a, 56b and

supply conductors

58, 60.

Considering details of circuit 46, control relays in the .circuit are indicated at 62, 64 and 66. Relay 62 comprises a solenoid 62a, and a pair of normally open switches 62b and 620. Relay 64 comprises a solenoid 64a, and a pair of normally open switches 64b and 640.

Relay 66 comprises a solenoid 66a and switches 66b, 66c, 66d and 66a, all but switch 66d being normally closed. Solenoid 66a is connected in parallel with discharge motor 30 by a pair of conductors 68 and 70. Switch 66:: functions as an interlock switch, as will be more fully explained, and for the purpose of this description is considered as having an actuating position when closed, and a nonactuating position when open.

Control circuit 48 includes a relay 72 and a relay switch 72a, which correspond to relay 66 and switch 66c, respectively, in circuit 46. Switch 722, like switch 66c, functions as an interlock switch, and for the purpose of this description is likewise considered as having an actuating position when closed, and a nonactuating position when open. Relays 73, 75 in circuit 48 correspond to

relays

62, 64, respectively, in circuit 46.

Timing circuit 50 includes a pair of timing relays 74 and 76. Relay 74 comprises a solenoid 74a and a normally closed switch 74b. Relay 76 comprises a solenoid 76a, a normally closed switch 76b, and a normally open switch 760.

Circuits

46, 48 and the timing circuit are interconnected through an interlock circuitcomprising a pair of

conductors

78, 79, with conductor 78 connected to supply conductor 58, interlock switch 72c, a conductor 80, interlock switch 66, a pair of

conductors

82 and 84, switch 7 6c, and a conductor 86. The functioning of this interlock circuit will later become apparent.

Considering now the operation of the circuitry described, prior to a charge of veneer reaching receiving station 31, and on closing of power switches 56a, 56b, power is supplied to timing relay solenoid 76a through supply conductor 60 and a conductor 88, conductor 82, interlock switch 66c, conductor 80, interlock switch 72e, conductor 79, and conductor 78 which is connected to con 'ductor 58. With solenoid 76a energized, switch 76b is opened and switch 76c is closed. At this time, relay 76 is the only one in circuitry 44 which is energized.

Upon a charge of veneer sheets traveling toward receiving station 31, the leading edge of the first sheet in the charge strikes gate 32 causing it to swing to the right from its lowered position in FIG. 1, and with swinging of the gate, gate switch mechanism 35 is actuated. The

mechanism includes a normally open switch 35a and a normally closed switch 35b. With the gate swung to the right, switch 35a closes and switch 35b opens, and this situation remains until the trailing edge of the last sheet in the charge has traveled beyond the gate, allowing the gate to return to its lowered position.

On closing of switch 35a, acircuit is completed between

supply conductors

58 and 60 and relay 62, comprising a conductor 90, switch 35a, a pair of

conductors

92 and 94, relay solenoid 62a, a pair of

conductors

96 and 98, switch 66b, and a conductor 100. Thus, relay 62 is energized.

With energizing of relay 62, switches 62b and 62c close. Switch 62c, on closing, completes a holding circuit paralleling switch 35a for maintaining relay 62 energized independently of switch.35a, this circuit comprising a conductor 102, switch 620, a conductor 104, conductor 92, and conductor 94. Nothing further happens until the charge has completely passed the gate and the gate has returned to its lowered position.

With relowering of the gate, switch 35a opens and switch 35b closes. On closing of. switch 35b, a power circuit is

completedbetween supply conductors

58, 60 and relay 64, this circuit including a conductor 106, switch 35b,.a pair of

conductors

108 and 110, switch 62b which is now closed, a conductor 112, relay solenoid 64a, a conductor 97, conductor 98, switch 66b, and conductor 100. Relay 64 is thus energized, whereupon switches 64b and 64c close.

Closing of switch 64b completes a holding circuit paralleling switch 35b for maintaining relay 64 energized independently of switch 35b. This circuit comprises conductor 102, switch 620, conductor 104, switch 64b, a

conductor 113, conductor 110, switch 62b, and conductor 112.

With interlock switches 66e and 72e closed, on closing of switch 640, a power circuit is completed between

supply conductors

58 and 60, and relay 66 and discharge motor 30 through the interlock circuit previously described. More specifically, this circuit comprises, progressing from conductor 58,

conductors

78, 79, the two closed interlock switches,

conductors

82, 84, now closed switch 760, conductor 86, switch 64c, a conductor 114, switch 66c, a pair of

conductors

116 and 118, the parallel combination of relay solenoid 66a and discharge motor 30, and a conductor 120. It is particularly important to note here that in order for power initially to be supplied relay 66 and motor 30, it is necessary that both of the interlock switches be in their closed or actuating positions. If either is open at the time when switch 64c closes, then control circuit 46 will remain in a condition where only relays 62 and 64 are energized and relay 66 is deenergized, until such time thereafter as both of the switches close.

With this power circuit completed to motor 30, it starts and drives rolls 26, 27. Sheets of veneer resting on the rolls which previously had passed under gate 32 are now discharged from receiving station 31.

At the same time that motor 30 begins running, relay switches 66b, 66c, 66d and 662 are actuated. These switches are ganged together in such a manner that on energizing of the relay, normally open switch 66d closes before the other normally closed switches open. This is necessary in order to prevent switch 660 from breaking the circuit initially supplying power to relay 66 and motor 30 before switch 66d can complete a holding circuit for the relay and motor.

On closing of switch 66d, such a holding circuit for relay 66 is established between the supply conductors, comprising conductor 120, the parallel combination of motor 30 and relay solenoid 66a, conductor 118, switch 66d, a conductor 122, switch 74b, and

conductors

124, 78. So long as switch 74b is closed, this holding circuit remains complete and the motor continues to run. On opening of switch 66b (which it will be remembered occurs immediately after switch 66d closes), the circuits previously discussed supplying power to relays 62 and 64 arebr-oken, and these two relays are deenergized. With opening of switch 66e, the circuit connecting relay 76 between

conductors

58, 60 is broken, and timing relay 76 becomes deenergized, with closing of switch 76b and opening of switch 760.

On closing of switch 76b power is supplied to timing relay 74 through a circuit comprising supply conductor 60, switch 76b, a conductor 126, relay solenoid 74a, and supply conductor 58. Timing relay 74 is of the type where, after its solenoid is supplied with power, a predetermined period of time elapses before switch 74b opens. During this period of time, discharge motor 30 continues to run, and sheets are discharged from the receiving station. The time period is chosen to be long enough so that the longest sheets expected to be handled will be completely discharged from the station. When the period has elapsed, switch 74b opens and breaks the circuit supplying power to why 66 and motor 30, whereupon the discharge motor stops.

With relay 66 now deenergized, switch 662 again closes, to recomplete the interlock circuit and also the circuit supplying power to timing relay 76. Relay 76, like relay 74, is of the type wherein, on being energized, delay occurs before its switches are actuated. Thus, switch 760, which is included in the interlock circuit, is held open for a' period of time, and during this time, no discharge of sheets can occur from either station. The purpose for having this delay at the completion of the discharge of a charge of sheets from receiving station 22 is to permit the otfbearing conveyer, which is now carrying away the just-discharged sheets, to clear adequate room to receive more sheets. This assures that sheets coming from one station will not fall upon sheets coming from another station. After the period of delay mentioned, switch 76b opens and switch 760 closes.

This completes the operation of the control circuitry during the passage of a charge of sheets through receiving station 31. The operation of circuit 48 for receiving station 36, during the passage of veneer sheets therethrough, is similar to the operation just described for circuit 46, the relays which are energized in this instance, however, being relays 73, 75 and 72.

Considering now what happens if a charge of sheets is received in station 36 at the same time that another charge is being cleared from station 31, it will be recalled that during the discharge of sheets from station 31, relay 66 is energized and interlock switch 66e is in its open or nonactuating position. It will also be recalled that switch 66e is included in the interlock circuit, which must be complete in order for the discharge motor of either receiving station initially to receive power and start to run. Hence, during the time that sheets are being discharged from station 31, discharge motor 30a cannot operate, and sheets are prevented from being discharged from station 36. A similar situation exists if a charge of sheets is received in station 31 during discharge of sheets from station 36. In this case, motor 30 in station 31 is prevented from starting by reason o switch 72e being open.

From the foregoing description it should be apparent that clearing is initiated in each station upon the gate in the station being swung away from and then returned to its lowered position, and only after the completion of any clearing which may be occurring in the other station when the gate returns to its lowered position. Thus, the sequence in which clearing from the stations is accomplished is determined by the sequence in which respective stations receive charges of sheets. The organization contemplated inhibits stacking up of sheets in the stations (each station clearing as rapidly as possible after it receives a charge of sheets), and permits the dryer to handle sheets of various sizes without requiring special adjustments for each size. Since clearing can begin only when a charge has passed completely beyond a predetermined point in the unloader, it makes no difference how long the sheets in the charge are; clearing will begin only after all sheets in the charge are in a position where they are ready to be'cleared. If, for example, one of the stations should completely receive two charges of short sheets during the time that the other station is receiving a single charge of long sheets, the two charges of short sheets would be cleared, one after another, before the later single charge is cleared.

Stacking of sheets, one upon another, on the oifbearing conveyer is eliminated, since the control circuitry permits only one receiving station at a time to be cleared. This reduces damage and greatly simplifies sorting or other Work operations performed in the sheets when occupying the otfbearing conveyer.

Turning now to the modified form of the invention illustrated in FIGS. 3, 4, and 5, and considering first of all FIGS. 3 and 4, what is shown at 128 at the left of FIG. 3 is the offbearing end of a veneer dryer. An unloader 130 is adapted to unload veneer sheets as they emerge from the dryer, and at 132 (at the right of FIG. 4) is the infeed end of an offbearing conveyer adapted to receive and carry away sheets which are discharged from the unloader.

Dryer 128 is similar in construction and operation (to the one illustrated in FIG. 1, and includes a pair of decks shown at 134 and '136 for transporting sheets of veneer.

Unloader 130 is a right angle unloader adapted first to receive and transport sheets a certain distance forwardly away fromthe dryer (to the right in FIG. 3), and then to transport them to one side of the dryer, or

at right angles to the direction in which the sheets are first moved from the dryer, whence the sheets are discharged onto conveyer 132 which carries them away.

The unloader includes receiving stations or

decks

138 and 140 which are adapted to receive charges of sheets coming from

decks

134 and 136, respectively, in the dryer. The unloader includes for each receiving station power-driven unloading means, such as pinch rolls 142 for removing sheets from a dryer deck and feeding them into the station. Additionally, each station is provided with hurry-up means, such as rolls 144, for accelerating sheets into the station away from the pinch rolls, and with discharging means, such as jump belts 146 for discharg ing sheets from the station onto conveyer 132. The pinch rolls are driven continuously by a suitable motor (not shown). The hurry-up rolls are interconnected by a chain 148 so that they may be driven in unison, and are operated intermittently (as will be more fully developed) by another motor illustrated schematically in FIG. at 149. The jump belts are trained over rollers, such as those shown at 150, and are driven continuously by yet another motor (not shown). The upper runs of the belts are supported on rails, such as rail 152 shown in FIG. 4, and these rails may be shifted up or down to raise or lower the belts. A ram 154 is provided which on extension shifts the rails of a station up, and on contraction drops the rails.

Describing generally how sheets are handled in the unloader, veneer sheets which emerge from a deck in the dryer are accelerated by the pinch rolls into the receiving station for the deck in the unloader. The sheets are moved by the hurry-up rolls to a position where they overlie the jump belts in the receiving station, against a stop such as stop 151, whence the hurry-up rolls are stopped. Thereafter, ram 154 in the station is actuated to shift the moving jump belts (which are normally maintained below the level at which the hurry-up rolls support the sheets) up into contact with the stopped sheets, and the belts transport the sheets to one side of the dryer, where they are discharged onto the ofl'bearing conveyer. Reference is made to United States Patent 3,087,597, issued April 30, 1963, for a description of an unloader similar to the one just outlined.

According to the invention, each receiving station is provided with a gate which extends transversely of the path of travel of sheets entering the station. Such gates for stations 13 8 and 140 are shown at 156 and 158, respectively. The gates are suitably pivoted adjacent opposite sides of the unloader and are ganged to

gate switch mechanisms

160 and 162, respectively, which they actuate when they are swung about their pivotal mountings.

Gates

156 and 158 function similarly to

gates

32 and 37 in the unloader shown in FIG. 1, in detecting the trailing edges of veneer sheets.

According to the invention, the gate switch mechanisms in the two stations are operatively interconnected through control circuitry 164 shown in FIG. 5 which controls the discharge of sheets from the stations. Such circuitry, and referring to FIG. 5, includes a first control circuit 166 and a second control circuit 168. In viewing FIG. 5 it is seen that control circuit 166 includes gate switch mechanism 160 having a gate switch 160a, and that control circuit 168 is substantially the same as circuit 166 except that it includes gate switch mechanism 162 with its gate switch 162a.

Circuit 166 includes a jump solenoid 170 ganged to a valve 170a controlling the supply of fluid under pressure to ram 154 in station 138. The solenoid on being energized, adjusts valve 170a to cause extension of ram 154 and raising of the jump belts in receiving station 138. Similarly, circuit 168 includes a jump solenoid 172 ganged to a valve 172a for controlling the supply of fluid under pressure to the ram like ram 154 in station 140. The solenoid on being energized adjusts valve 172a to cause extension of this ram.

Power is supplied

circuits

166 and 168 from a suitable source of power (not shown) through power terminals 174, 176, ganged power switches 178a, 1781), and power supply conductors 180, 182. The two control circuits are operatively interconnected through an interlock circuit comprising a conductor 184 connected to supply conductor 180, an interlock switch 173a which is ganged to solenoid 173, a conductor 186, another interlock switch a which is ganged to solenoid 175, and a conductor 188. Each of the interlock switches is considered herein as having an actuating position (when closed) and a nonactuating position (when open).

Considering control circuit 166, it includes a roll motor timing relay 190, a roll motor starting relay 192, a pair of control relays 194 and 196, and a discharge timing relay 198. Motor timing relay 190 comprises a solenoid 190a, a pair of normally open switches 19Gb and 190s, and a normally closed switch 190d. Motor starting relay 192 comprises a solenoid 192a, and normally open switches 192b, 192c and 192d. Control relays 194 and 196 each have a solenoid, 194a and 196a, respectively, and a pair of normally open switches 194b, 194a, and 196b, 1960, respectively. Discharge timing relay 198 comprises a solenoid 198a, a normally open switch 198]; and a pair of normally closed switches 1980 and 198d.

Assuming that the power switches are closed and that no sheets of veneer have yet begun to enter receiving station 138, roll motor timing relay 190 is initially energized through a circuit connecting it to the power supply conductors comprising a conductor 200, gate switch 16011, a conductor 202, relay solenoid 190a, and a conductor 204. Nothing changes this condition of the parts until a charge of veneer emerging from deck 134 in the dryer strikes gate 156.

When veneer strikes the gate, the gate swings and causes gate switch 160a to open and to break the circuit just described supplying power to relay 190. Relay 190 remains deenergized, and nothing further occurs in circuit 166, until the trailing edge of the last sheet in the charge has passed beyond the gate, whereupon the gate returns to its lowered position with reclosing of the gate switch.

On reclosing of the gate switch, power is again supplied to relay 190 through the same circuit which initially supplied it with power. The relay is constructed in such a manner that upon energizing of solenoid 190a, switch 190ccloses immediately, but switches 19012 and 190d remain in their normal positions for a predetermined span of time which will be referred to herein as the time delay period of relay 190'.

With closingof switch 1900, and during the time delay period of relay 190, a circuit is completed between the supply conductors for supplying power to relay 192 comprising a pair of

conductors

206 and 208, switch 190d, a conductor 210, switch 1900, a conductor 212, solenoid 192a, and a conductor 214. Relay 192 is thus energized during the time delay period of relay 190.

On power being supplied relay 192, switch 192d of the relay closes, to start up roll motor 149 which drives hurryup rolls 144 in station 138. This motor continues running throughout the time delay periods of relay 190. With rolls 144 moving, the charge of sheets which has entered receiving station 138 is transported further int-o the station and against stop 151.

Switches 192b and 1920 also close with energizing of relay 192. Closing of switch 192E; completes 'a holding circuit for relay 190 connecting solenoid 190a to supply conductor independently of the gate switch, this circuit comprising conductors 206 and 209', switch 192b, a conductor 216, and conductor 202. Closing of switch 1920 completes a circuit between the supply conductors for supplying power to control relay 194 comprising conductor 206, a conductor 218, switch 192e, a pair of

conductors

220 and 222, relay solenoid 194a, and :a conductor 9 224. With power now supplied to relay 194, its switches 19412 and 1940 close.

On closing of switch 1940, a holding circuit is completed for relay 194 connecting solenoid 194a to supply conductor 180 independently of switch 1920, this circuit including conductor 222, switch 194e, a conductor 226, switch 198d which is still closed, and a pair of

conductors

228 and 230.

Nothing further happens until the time delay period of relay 190 has elapsed. When this occurs, switch 19Gb closes and switch 190d opens. These two switches are so constructed that 1901) closes before 190d opens, and this permits relay 196 (which is initial-1y supplied with power through a circuit including switch 19Gb as will be explained) to be energized before relay 190 is deenergized.

On closing of switch 19% *a circuit is completed between the supply conduotors for supplying power to relay 196 comprising conductor 230, a conductor 232, switch 194b, a pair of

conductors

234 and 236, switch 190b,

a conductor 238, relay solenoid 196a, and a conductor 240. Thereafter, on opening of switch 190d, the circuit previously described supplying power to relay 192 is broken. On deenergizing of relay 192, switches 192b, 1920 land 192d open, and the roll motor which is driving rolls 144 stops. If gate switch 160a is closed at this time, which it should be if no new charge of veneer is then entering the station, relay 190 will remain energized; if thegate switch is open, then the relay will be deenergized and switches 190b, 1900 and 190d will return to their normal positions. The time delay period of relay 190 is chosen so that when hurry-up rolls 144 are stopped, the charge of veneer which they have moved into the receiving station will then be positioned directly over the jump belts.

With energizing of relay 196, switches 196b and 1960 close. On closing of switch 196b, a holding circuit is provided for relay 196 connecting solenoid 196a to supply conductor 180 independently of switch 19% comprising conductor 238, a conductor 242, switch 196b,

conductors

236 and 234, switch 194b, and

conductors

232 and 230.

Assuming that interlock switches 175a and 173a in the interlock circuit previously described are closed, on closing of switch 196e, circuits are completed between the supply conductors for supp-lying power to jump solenoid 170, solenoid 175 and to discharge timing relay 198. The circuit supplying power to the jump solenoid and solenoid 175 comprises the interlock circuit, a conductor 244, switch 1960, a pair of

conductors

246 and 248,

solenoids

170, 175, and a conductor 250. The circuit supplying power to the discharge timing relay comprises the interlock circuit, conductor 244, switch 196e,

conductors

246, 248, a conductor 252, relay solenoid 198a, "a conductor 254, switch 198e, a conductor 256 and conductor 250. It should be noted here that in order for either the jump solenoid (and solenoid 175) or the discharge timing relay to be initially supplied with power, it is necessary that the interlock circuit be complete, with both of the interlock switches in their closed or actuating positions. If the interlock circuit is open at the time when switch 1960 closes, then control circuit 166 will remain in a condition with only relays 194 and 196 (and possibly 190, depending upon whether the gate switch is closed) energizcd, until such time thereafter as the interlock circuit is closed.

n energizing of relay 198, its switches 198b and 198d are actuated immediately, with switch 19% closing before switch 198d opens. This prevents the circuit initially supplying power to relay 198 from being broken before a holding circuit can be established. Switch 1980, however, remains in its normally closed position for a predetermined span of time which is referred to herein as the time delay period of relay 198.

On closing of switch 198!) a holding circuit is established for relay 198 connecting solenoid 198a to supply conductor 180 independently of switch 196a and of the interlock circuit, this holding circuit comprising conductor 10 230, switch 19% and

conductors

248 and 252. Simultaneously, a holding circuit is established for maintaining jump solenoid and solenoid connected to supply conductor independently of switch 1960 comprising conductor 230, switch 1985, and conductor 248'.

On opening of switch 198d, the circuit thensupplying power to control relay 194 is broken, whereupon relay 194 becomes deenergized and switches 194b and 1940 open. When switch 1 94b opens it breaks the circuit then supplying power to control relay 196, whereupon relay 196 becomes deenergized and switches 19612 and 1960 open.

Returning to the jump solenoid, upon being energized, the solenoid actuates valve 170a causing ram 154 to extend and the jump belts to be moved up into contact with the charge of veneer which overlies them. The belts pick up the sheets in the charge and transport them to one side of the dryer, where they fall onto the oilfbearing conveyer.

The jump solenoid remains energized, and hence the belts remain elevated, throughout the time delay period of relay 198, and this period is chosen to be long enough to permit the belts completely to discharge the sheets onto the olfbearing conveyer. At the same time that the jump solenoid 170 is energized, interlock switch 175a opens by reason of energizing of solenoid 175. Thus, the interlock circuit is broken while receiving station 138 is being cleared of a charge.

At the end of the time delay period of relay 198, switch 198a opens and breaks the circuit then supplying power to the relay, whereupon switches 198b, 1980 and 198d return to their normal positions, with switches 1980 and 198d closing and switch 198-b opening. On opening of switch 19811, the holding circuit earlier established for jump solenoid 170 and solenoid 175 is broken, and the solenoids become deenergized. On this occurring the jump belts are relowered, and interlock switch 175 is reclosed.

Control circuit 168 is constructed similarly to circuit 166, and functions similarly in controlling the flow of veneer in receiving station 140*.

Relays

260, 262, 264-, 266 and 268 in circuit 168 correspond to

relays

192, 196, 194 and 19 8, respectively, in circuit 166.

Solenoids

172 and 173 correspond to

solenoids

170 and 175, respective-1y, in circuit 166. .In circuit 166, the jump solenoid 17 0 and solenoid 1 75 cannot be initially energized unless, at the time, the interlock circuit is complete. Thus, when jump solenoid 172 and solenoid 173 in circuit 168 are energized, and interlock switch 1730 is open, it is impossible for jump solenoid 170 to become energized. The reverse is true with respect to energizing

solenoids

172, 173 during the time when

solenoids

170, 175 are energized. Hence, sheets can be discharged onto the otfbearing conveyor from only one of the receiving stations at a time.

Additionally, it will be apparent that receiving

stations

138 and 140 are cleared in the same order that

gates

156 and 158 detect the trailing edges of sheets entering the station. Thus, unloader 130 readily handles sheets of various sizes coming from the dryer, without the need for any special adjustments in the unloader for diflerent sizes.

Although the unloaders discussed herein have been shown with only two receiving stations, it should be apparent that the present invention is easily adaptable to unloaders having more than two decks. In such a case, the control circuitry would include a control circuit and an interlock switch corresponding to each of the decks in the unloader.

While specific preferred embodiments of the invention have been shown herein for the purpose of illustration, it will be apparent to one skilled in the art that variations and modifications may be made without departing from the basic principles of the invention, and it is desired to cover all such variations and modifications which come within the scope of the appended claims.

- It is claimed and desired to secure by Letters Patent: 1. In sheet-unloading apparatus, the combination of at least two conveyer decks for transponting sheets, collecting means for collecting sheets coming from each of said decks,

each deck having a receiving station into which sheets travel prior to traveling onto said collecting means, said receiving stations each including an intermittently actuated discharging means producing travel of sheets onto the collecting means, and

control means controlling the flow of sheets traveling from the two conveyer decks onto said collecting means by controlling actuation of the respective discharging means of the decks receiving stations, preventing one discharging means from being actuated when the other is being actuated.

2. The apparatus of claim 1, wherein the discharging means for a receiving station is actuated only after the station has completely received a charge of sheets, and the control means is operable, in the event charges of sheets travel simultaneously into the receiving stations of .both decks, to actuate the discharging means of that receiving station which first completely receives a change of sheets prior to actuating the discharging means of the other station.

3. The apparatus of claim 1, wherein the control means includes a detector for each receiving station operable to detect the trailing ends of a charge of sheets traveling into the station, and the control means produces a sequence 12 of actuation of the discharging means of the two decks corresponding to the sequence in which the detectors of the receiving stations detect the trailing ends of charges of sheets.

4. The apparatus of claim 3, wherein the control means includes an inter-lock system comprising an interlock device for each station which interlock device has actuating and nonactuating positions, and the discharging means of one station is actuatable to produce a discharge of sheets only when the interlock device of the other station is in its actuating position.

5. The apparatus of claim 4, wherein the discharging means of each station includes a motor which is actuated to actuate the discharging means of the station, the control means includes a circuit which is closed by the detector for a station on the detector detecting the trailing ends of sheets in a charge, and such circuit on being closed produces actuation of the motor, and the interlock device for a station comprises a switch shifted to its nonactuating position on such circuit being closed.

References Cited by the Examiner UNITED STATES PATENTS 8/1964 Nigrelli 19832 12/ 1965 Ni grelli 19832

Claims

1. IN SHEET-UNLOADING APPARATUS, THE COMBINATION OF AT LEAST TWO CONVEYOR DECKS FOR TRANSPORTING SHEETS, COLLECTING MEANS FOR COLLECTING SHEETS COMING FROM EACH OF SAID DECKS, EACH DECK HAVING A RECEIVING STATION INTO WHICH SHEETS TRAVEL PRIOR TO TRAVELING ONTO SAID COLLECTING MEANS, SAID RECEIVING STATIONS EACH INCLUDING AN INTERMITTENTLY ACTUATED DISCHARGING MEANS PRODUCING TRAVEL OF SHEETS ONTO THE COLLECTING MEANS, AND CONTROL MEANS CONTROLLING THE FLOW OF SHEETS TRAVELING FROM THE TWO CONVEYOR DECKS ONTO SAID COLLECTING MEANS BY CONTROLLING ACTUATION OF THE RESPECTIVE DISCHARGING MEANS OF THE DECKS'' RECEIVING STATIONS, PREVENTING ONE DISCHARGING MEANS FROM BEING ACTUATED WHEN THE OTHER IS BEING ACTUATED.