JPH09136757A - Sheet stacker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stack sheets in regular order without generating disorder and a jam to the sheets. SOLUTION: A sheet discharge conveyor 5 is disposed with step difference on the front side of a sheet conveying conveyor 1 for transferring sheets continuously at high speed, and a drop guide path Y is provided on the front side. The sheets S delivered from the sheet discharge conveyor 5 are fed from the drop guide path Y into a sheet stacking part 11 for stacking, and when the sheets are stacked to the specified height, the sheet S is stopped being sucked by suction-holding mechanism X provided at the feed end part of the sheet dishcarge conveyor 5 so as to hold an interval to the sheet S directly in front. After the lapse of fixed time from the suction of the sheet S, suction is released, and sheet receiving members 26, 27 provided at the lower end part of the drop guide path Y are protruded into the drop guide path Y. The head batch-divided sheets fed into the drop guide path Y from the sheet discharge conveyor 5 are received by the sheet receiving members 26, 27, and after a stack of sheets in the sheet stacking part 11 is discharged, the sheet receiving members 26, 27 are retreated to continue stacking of the sheets.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet stacker for sequentially stacking sheets such as corrugated cardboard sheets continuously fed from a sheet processing apparatus such as a printer / slotter.

[0002]

2. Description of the Related Art Sheets which are continuously sent out at high speed from a sheet processing apparatus such as a printer / slotter are received by a sheet conveying conveyor and are conveyed to a sheet stacking section in the front,
2. Description of the Related Art A sheet stacker in which sheets are sequentially stacked on a table provided in the sheet stacking unit at a constant height and discharged is known.

In the above-mentioned sheet stacker, as shown in FIG. 8, a discharge guide path 43 having a front guide 41 and a back guide 42 is provided at the discharge end of the sheet conveying conveyor 40, and the lower end of the drop guide path 43 is in front of and behind. Further, a sheet receiving member 44 is provided which can be opened and closed, which is activated when switching the stacked sheets according to batch classification.

Such a sheet stacker has a sheet conveying conveyor 40 centered on the supply end of the sheet conveying conveyor 40.
By swinging upward, the discharge end is moved upward, and the drop guide path 43 that rises together with the discharge end.
The sheet S is continuously fed to the table, and the sheet S is dropped from the drop guide path 43 and stacked on a table on which a floor plate such as a pallet or a veneer plate of the sheet stacking unit 45 is placed.

When the sheets are stacked on the table to a predetermined height, the sheet receiving member 44 is closed to receive the sheet S therein, while the sheet pile on the table is discharged together with the floor plate, and the sheet pile is discharged. After that, the sheet conveying conveyor 40 is swung downward, the sheet receiving member 44 is opened at the lower limit position thereof, and the plurality of sheets S stored in the drop guide path 43 are dropped downward, and at the same time, the sheet conveying conveyor 40 is moved upward. The sheets S are continuously piled up while swinging.

In the above-mentioned sheet stacker, since the sheets S can be temporarily stored in the drop guide path 43 when the sheet pile of the sheet stacking section 45 is discharged, it is sufficient for the sheets S continuously fed at a high speed. It has a feature that it can correspond to.

[0007]

By the way, in the above-mentioned conventional sheet stacker, since the sheet S is continuously sent out from the sheet conveying conveyor 40 to the drop guide path 43 at a high speed, the sheet S is dropped and moved in the drop guide path 43. Sheet S
Has a fast falling speed, and the sheets S are continuously dropped with an extremely small interval. For this reason, at the time of batch division when starting the next stacking of sheets, the sheet receiving member 44 cannot be reliably closed between the sheets S that are in close proximity and continuously falling, as shown in FIG. The stacks may be disturbed or clogged.

At this time, it is necessary to manually remove the disorder and clogging of the sheet S. Since such an operation is performed around the vertically moving sheet conveying conveyor, it is extremely dangerous.

Further, as the height of the sheets S stacked in the sheet stacking unit 45 increases, the sheet conveying conveyor 4
The inclination of 0 also becomes steep, and the sheet S sent out from the sheet conveying conveyor 40 has a large collision angle when colliding with the front guide 41 of the drop guide path 43, and the sheet S is inclined in the drop guide path 43. To fall.

For this reason, the sheets S stacked in the sheet stacking section 45 are likely to be disturbed as the height of the ridges increases, and the sheets S cannot be received by the sheet receiving member 44 even during batch division. There are cases.

In the sheet stacker, a floor plate is supplied on the table of the sheet stacking unit 45, and sheets are stacked on the floor plate. However, since the floor plate is discharged together with the sheet pile, the sheet pile is placed on the table. Each time the paper is discharged, it is necessary to supply the next floor plate on the table.

In the conventional sheet stacker, it is dangerous because an operator enters the sheet stacker below the sheet conveyor where the discharge end goes up and down to feed the floor sheet. In particular, it is extremely dangerous if the sheet conveying conveyor suddenly starts descending due to a malfunction of the apparatus.

A first object of the present invention is to ensure that the sheets can be stopped and held without being disturbed in the sheet storage section at the time of batch division when discharging the sheet piles of the sheet stacking section. It is to provide a sheet stacker that has

A second object of the present invention is to provide a sheet stacker capable of safely supplying a floor plate onto the table of the sheet stacking section from below the sheet conveying conveyor.

[0015]

In order to solve the above-mentioned first problem, according to the present invention, a sheet conveying conveyor for continuously transferring sheets and a front and rear end of the sheet sent out from the sheet conveying conveyor are provided. A drop guide path having a front guide and a back guide for guiding a drop movement, and a sheet receiving member provided so as to be retractable with respect to the lower part of the drop guide path, and continuously from the sheet conveyor to the drop guide path. In the sheet stacker in which the sheets to be conveyed are sent onto the table of the sheet stacking unit provided below the drop guide path to be stacked, a sheet discharge conveyor is provided between the sheet transport conveyor and the drop guide path. Arrange them with a step so that the sheet transport surface is lower than the sheet transport surface of the sheet transport conveyor. To the feed end, it was adopted a structure in which a stop means for temporarily stopping the sheet at the sheet batch classification.

In the above-mentioned sheet stacker, when the sheets are stacked on the sheet stacking unit to a predetermined height, the stop means is operated to temporarily stop the sheet on the sheet discharging conveyor, and the sheet is immediately separated from the immediately preceding sheet. When the temporarily stopped sheet is re-fed, the sheet is received by the sheet receiving member below the drop guide path.

Instead of the stopping means, the sheet conveying speed of the sheet conveying conveyor may be slower than the sheet conveying speed of the sheet discharging conveyor when dividing the sheets into batches.

In order to solve the second problem, in the present invention, the sheet conveying conveyor and the sheet discharging conveyor in the invention are fixedly arranged so as to incline with an upward slope toward the discharging end of each conveyor, In addition, the front guide and the back guide forming the drop guide path are also fixedly arranged, and an elevating device for moving the table of the sheet stacking part up and down with respect to the drop guide path is adopted.

In the above invention, since the sheet conveying conveyor is fixedly arranged, it is possible to safely perform the work of supplying the floor board from below the sheet conveying conveyor onto the table of the sheet stacking section.

[0020]

Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, a sheet S sent from a sheet processing apparatus A such as a printer / slotter is sent onto a sheet carrying conveyor 1 and carried forward.

The sheet conveying conveyor 1 comprises a first conveyor 2, a second conveyor 3 and a third conveyor 4, each of these conveyors 2, 3 and 4 having a fixed arrangement inclined at an upward slope toward the discharge end. Has been done.

Here, the sheet conveying conveyor 1 stacks the sheets S in a tile shape on the first conveyor 2 by making the sheet conveying speed of the first conveyor 2 slower than the discharging speed of the sheets S sent from the sheet processing apparatus A. The sheet may be transferred in the roof tile-like state, or the first
The sheet conveying speed of the conveyor 2 is set to be equal to or higher than the sheet conveying speed of the sheet processing apparatus A, and a required space is provided between the sheets S on the first conveyor 2 so that the sheets S are spaced apart from each other.
May be transferred.

The sheet discharging conveyor 5 provided in front of the sheet conveying conveyor 1 is composed of a belt conveyor having a plurality of rows of conveyor belts 6 as shown in FIG. The sheet discharge conveyor 5 has a supply end portion arranged below the discharge end portion of the sheet conveying conveyor 1 and is fixedly arranged so as to incline upward from the supply end portion to the discharge end portion. The inclination angle is smaller than the inclination angle of the sheet conveying conveyor 1.

As shown in FIGS. 2 and 3, a belt conveyor 7 is provided above the sheet discharge conveyor 5. This belt conveyor 7 has a double row of belts 8, and each belt 8 is moved in the direction of the arrow in FIG.

The sheet S delivered from the discharge end of the sheet conveying conveyor 1 comes into contact with the inclined portion 9 provided on the lower belt 8a of the belt 8 to weaken the momentum, and the sheet S is delivered obliquely downward by contact with the lower belt 8a. Then, the sheet is fed to a fixed position on the sheet discharge conveyor 5.

A stopper plate may be provided instead of the belt conveyor 7, and the sheet S may be supplied to a predetermined position on the discharge conveyor 5 by contacting the stopper plate.

At the supply end of the sheet discharge conveyor 5, a suction holding mechanism X is provided as a stopping means for stopping the sheet S on the conveyor 5. The suction holding mechanism X is provided with a plurality of vacuum caps 10 between a plurality of rows of conveyor belts 6, and the vacuum caps 10 are moved up and down by an elevator device (not shown). When the sheets S are lifted for batch division, they project onto the sheet conveying surface of the sheet discharge conveyor 5 and hold the sheets S by suction.

A drop guide path Y is provided on the front side of the discharge conveyor 5, and the sheet stacking section 11 is provided below the drop guide path Y.
Is provided.

The fall guide path Y is a plate-shaped front guide 1
2 and a plate-shaped back guide 13, the front guide 12 is movable with respect to the back guide 13, and its position is adjusted according to the length of the sheet S sent from the discharge conveyor 5.

A pair of left and right side guides 14 are provided between the front guide 12 and the back guide 13. The side guide 14 is moved back and forth by the operation of the cylinder 15. A pair of cylinder plates 16 that support the cylinder 15 are screw-engaged with a screw rod 17 provided above the front guide 12 and the back guide 13. Therefore, by rotating the screw rod 17, the pair of side guides 14 is moved in the left-right direction.

As shown in FIG. 2, a front sheet receiving member 26 and a rear sheet receiving member 27 are provided in front of and below the lower end of the fall guide path Y. Sheet receiving member 26, 27
Of each of the cylinders 28 and 29 is moved in and out of the drop guide path Y by the operation of the cylinders 28 and 29.

The cylinder 28 of the front sheet receiving member 26 is fixed to the front guide 12, while the cylinder 29 of the rear sheet receiving member 27 is supported on the bar 30.

The bar 30 is connected to a part of the endless chain 31, and the rear sheet receiving member 27 is vertically moved by the movement of the endless chain 31. The upper limit stop position of the rear sheet receiving member 27 is the front sheet receiving member 2
It is located at a position opposite to 6. The rear sheet receiving member 27 has a length capable of supporting more than half of the sheet S having the maximum paper width.

As shown in FIGS. 1 and 9, a delivery conveyor 18 is provided on the floor surface of the sheet stacking section 11. As shown in FIG. 4, the delivery conveyor 18 has a double row of belts 19.

The table 20 provided on the feeding conveyor 18 includes a plurality of horizontal rails 2 between front and rear rails 22 of a quadrilateral frame 21.
3 are provided. The table 20 is moved up and down by a lifting device 24.

The lifting device 24 is provided with a chain 25 on both sides of the table 20, the table 20 is fixed to a part of the chain 25, and the table 20 is moved up and down by the movement of the chain 25.

The horizontal rail 23 of the table 20 is
The lower limit of the table 20 is stopped at a position where the table 20 enters the space between the belts 19 of the feed-out conveyor 18 and the upper surface of the horizontal rail 23 is lower than the upper surface of the belt 19 when the table 20 is lowered.

In the table 20, the solid line position shown in FIG. 2 is the upper limit stop position, and the upper limit stop position is slightly below the lower limit stop of the rear sheet receiving member 27.

Immediately above the upper limit stop position of the table 20,
A pair of scratch prevention sheet receivers 32 are provided at the front and rear.
The scratch prevention sheet receiver 32 appears and disappears from the sheet drop path of the drop guide path Y by the operation of the cylinder 33 supported by the front guide 12 and the back guide 13.

The sheet stacker shown in the embodiment has the above-mentioned structure, and when the sheet S is sent from the sheet processing apparatus A onto the sheet carrying conveyor 1, the sheet S is carried forward by the sheet carrying conveyor 1.

Here, in the embodiment, since the sheet conveying speed of the sheet conveying conveyor 1 is set to be lower than the sheet discharging speed of the sheet processing apparatus A, the sheets S are stacked on the sheet conveying conveyor 1 in a tile shape, The sheets S are conveyed in the tile-like stacked state.

The sheets S on the sheet conveying conveyor 1 are sequentially discharged from the discharge end of the conveyor 1, and the discharged sheets S are, as shown in FIG.
The contact with the sheet weakens the momentum, and the belt 8 moves so that the belt 8 is conveyed obliquely downward and is sequentially supplied to predetermined positions on the sheet discharge conveyor 5.

At this time, since the sheet conveying speed of the sheet discharging conveyor 5 is substantially the same as the sheet conveying speed of the sheet conveying conveyor 1, the sheets S fed onto the sheet discharging conveyor 5 are stacked in a tile shape, In the roof-like state, it is further transported to the front and sequentially discharged from the discharge end.

The sheet S sent from the sheet discharge conveyor 5 has its front end positioned by the front guide 12 and its rear end positioned by the back guide 13 and falls along the drop guide path Y.

Here, when the sheets S are at the beginning of stacking, the rear sheet receiving member 27 is at the upper limit stop position as shown in FIG. 2, and the rear sheet receiving member 27 and the front sheet receiving member 26 are It is in a state of protruding into the sheet drop path.

The scratch prevention sheet receiver 32 also projects into the sheet drop path, and the table 20 is at the upper limit stop position.

Therefore, the sheet S falling between the front guide 12 and the back guide 13 is supported by the front and rear sheet receiving members 26 and 27, and when the sheet S is received, the front sheet receiving member 26 moves in the sheet falling path. And the rear side sheet receiving member 27 begins to descend at the same time, and the sheets S are sequentially supplied and stacked on the rear side sheet receiving member 27. Further, the sheets S on the rear sheet receiving member 27 are aligned on both sides by the side guides 14 which are moved back and forth.

When the rear sheet receiving member 27 passes the position of the scratch prevention sheet receiving member 32, as shown in FIG. 5 (I).
The sheet S is received by the scratch prevention sheet receiver 32. When the rear sheet receiving member 27 descends to a position where it enters between the horizontal rails 23 of the table 20, the rear sheet receiving member 27 moves backward. When the rear sheet receiving member 27 is completely retracted from the sheet falling path, the cylinder 2 of the rear sheet receiving member 27
The bar 30 supporting 9 is raised to the upper limit position. At the same time, the scratch prevention sheet receiver 32 retracts from the sheet drop path.

Therefore, several stacked sheets S fall and are received by the floor plate B placed in advance on the table 20 as shown in FIG. 5 (II). Table 20 is seat S
Upon receiving the sheets, the sheets S start descending, and the sheets S sent from the sheet discharge conveyor 5 to the drop guide path Y are sequentially stacked on the table 20.

The table 20 descends to the position of the sensor TL ₁ shown in FIG. 6, and when the sensor TL ₁ detects the table 20, the vacuum cap 10 shown in FIG. 2 rises and is supplied onto the sheet discharge conveyor 5. One sheet S is adsorbed and stopped.

The sheet S is attached by the vacuum cap 10.
When is stopped and held, the third conveyor 4 of the sheet conveying conveyor 1 stops as shown in the time chart of FIG. 7.

The vacuum cap 10 releases the suction after a lapse of a certain time T ₁ from the start of the suction, and the sheet S immediately before the stop state is completely sent out from the sheet discharge conveyor 5 until the suction is released. Further, after the elapse of a certain time T ₁ , the sheet discharging conveyor 5 and the belt conveyor 7 above it are stopped, and at the same time, the third conveyor 4 starts to move at a speed lower than the normal operation speed, and the sheet S on the third conveyor 4 is moved. To the sheet discharge conveyor 5.

At this time, since there is a step between the third conveyor 4 and the sheet discharging conveyor 5, several sheets S are stored in the discharging conveyor 5 even if the sheet discharging conveyor 5 is stopped. Even if the sheet S is continuously sent out from the sheet processing apparatus A, there is no hindrance to the conveyance of the sheet S.

When a certain time T ₂ has passed since the suction of the vacuum cap 10 was released, the sheet discharge conveyor 5 and the belt conveyor 7 are activated to start the conveyance of the sheet S,
Further, the third conveyor 4 returns to the normal operating state.

Further, the front side sheet receiving member 26 and the rear side sheet receiving member 27 advance to support the sheet S discharged from the sheet discharging conveyor 5. Here, even the sheets S that are continuously fed in a tile shape are reliably divided into batches with a space between the sheets S. Therefore, when the sheet receiving members 26 and 27 move forward, they fall. Guideway Y
Since the sheet S does not exist in the sheet, there is no trouble of disturbing the sheet S, and the first sheet S batch-divided can be reliably received.

The table 20 reaches the lower limit position until the time T ₁ + T _{2 from} when the vacuum cap 10 starts adsorbing the sheet S until the front side sheet receiving member 26 and the rear side sheet receiving member 27 advance. After being lowered, the stacked sheets S are discharged at the lower limit position and the floorboard is supplied, and then moved up to reach the upper limit position.

Here, when the table 20 on which the stacked sheets S are placed descends to the lower limit position, the stacked sheets S are supported by the sending conveyor 18 together with the floor plate, and the stacked sheets S are sent by the operation of the sending conveyor 18.

When the stacked sheets S are sent out, the floor board B is supplied onto the table 20 at the lower limit stop position.

For supplying the floor board B, for example, a floor board supply conveyor is provided below the sheet discharge conveyor 5, the floor board is supplied to the supply conveyor from one lower side of the sheet discharge conveyor 5, and then the floor board is placed on the table 20 from the supply conveyor. May be supplied. Alternatively, the floor plate may be carried under the discharge conveyor 5 and the floor plate may be manually supplied onto the table 20 from below the sheet discharge conveyor 5.

In either case, since the sheet discharge conveyor 5 is fixed at a high place and the sheet conveying conveyor 1 is also fixed, the floor board B can be safely supplied onto the table 20. .

When the table 20 supporting the floor board B is raised to the upper limit position and stopped as shown in FIG. 2, the front side sheet receiving member 26 moves backward, and at the same time, the rear side sheet receiving member 27 starts descending, and thereafter. The same operation as described above is repeated.

The leading sheet S after batch sorting sent out from the sheet discharging conveyor 5 is supported only by the rear side sheet receiving member 27, and the sheets S stacked on the rear side sheet receiving member 27 are received as a scratch prevention sheet receiving member. You may make it transpose on the table 20 without going through 32.

As shown in the embodiment, by providing the front side sheet receiving member 26, even if the sheet S falls between the front guide 12 and the back guide 13 in a state of being inclined forward and downward, You can definitely receive it.

When the sheet S is dropped on the table 20 by the backward movement of the rear sheet receiving member 27, the sheet S may be scratched at the position where it comes into contact with the rear sheet receiving member 27. When the prevention sheet receiver 32 is provided, it is possible to prevent the sheet S from being scratched.

As shown in FIG. 1, the second conveyor 3
Is swingably supported as indicated by the chain line, and the second conveyor 3
The defective sheet S may be taken out of the sheet transfer path by swinging downward.

In the embodiment, the sheet conveying conveyor 1,
With the sheet discharge conveyor 5 and the drop guide path Y fixedly arranged, the sheet S is placed on the table 20 of the sheet stacking unit 11.
However, the conveyors 1 and 5 are swung upward around the supply end of the sheet conveying conveyor 1 while the sheet discharging conveyor 5 is moved to the falling guide path Y that moves upward together with the conveyors 1 and 5. The sheets S may be continuously fed to stack the sheets S on the table 20 of the sheet stacking unit 11. In this case, the cylinder 2 of the front and rear sheet receiving members 26, 27 is provided at the lower end of the drop guide path Y.
8 and 29 are fixed.

Further, in the embodiment, the sheet S is sucked and held by the vacuum cap 10 to stop the sheet S, and a gap is provided between the sheet S in the stopped state and the sheet S immediately before. The control device may control the sheet conveying speed of the sheet conveying conveyor 1 to be slower than the sheet conveying speed of the sheet discharging conveyor 5 so that the sheets 5 are spaced from each other.

[0069]

The present invention is configured as described above.
The following effects are obtained.

A sheet discharging conveyor is arranged at the front side of the sheet conveying conveyor with a step, and a stopping means is provided at the supply end of the sheet discharging conveyor. When the sheet batch is divided, the sheet is stopped by the stopping means to provide a space between the sheets. As a result, when the first sheet batch-divided by the sheet receiving member provided at the lower end of the drop guide path is received, the sheet receiving member interferes with the sheet and disturbs the sheet, or the sheet is jammed. It is possible to eliminate the trouble of causing it.

Further, since there is no trouble such as the disorder of the sheets when the sheets are stacked, it is not necessary for the operator to approach the sheet stacking portion, and the safety can be improved.

By providing a speed difference between the sheet conveying conveyor and the sheet discharging conveyor so that the sheets are spaced apart from each other, a stop means is not required and the apparatus can be easily assembled.

By arranging the sheet conveying conveyor, the sheet discharging conveyor, and the drop guide path in a fixed arrangement, it is possible to safely perform the work of supplying the floor plate to the table of the sheet stacking unit.

By making the inclination angle of the sheet discharging conveyor smaller than the inclination angle of the sheet conveying conveyor, it is possible to reduce the collision angle of the sheet with respect to the front guide of the drop guide path, so that the sheet falling on the drop guide path is disturbed. There is almost no, and the sheets can be stacked in an orderly manner.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an embodiment of the present invention.

FIG. 2 is an enlarged schematic view of the discharge conveyor and the table portion of the same.

FIG. 3 is a plan view of FIG.

FIG. 4 is a plan view showing the table and the feed conveyor according to the first embodiment;

5 (I) and (II) are diagrams showing the operation of the sheet stacker in stages.

FIG. 6 is a schematic view showing a state at the same time when dividing into batches.

FIG. 7: Time chart showing the operation of various conveyors

FIG. 8 is a front view showing a part of a conventional sheet stacker.

[Explanation of symbols]

 1 Sheet Conveyor 5 Sheet Ejecting Conveyor 10 Vacuum Cap 12 Front Guide 13 Back Guide 18 Feeding Conveyor 19 Belt 20 Table 24 Lifting Device 27 Rear Sheet Receiving Member 29 Cylinder X Adsorption Holding Mechanism Y Fall Guide Path

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Hiromi Hasuike 200 Shibukawa, Shimizu City Rengo Co., Ltd. Shimizu Plant

Claims (4)

[Claims] 1. A sheet conveying conveyor for continuously transferring sheets, a drop guide path having a front guide and a back guide for guiding a drop movement of front and rear ends of a sheet sent from the sheet conveyor, and the drop guide path. A sheet receiving member that can be retracted from the lower part of the sheet, and the sheets that are continuously fed from the sheet conveyor to the drop guide path are placed on the table of the sheet stacking section provided below the drop guide path. In the sheet stacker configured to be sent to and stacked on the sheet stacker, the sheet discharge conveyor is disposed between the sheet transport conveyor and the drop guide path with a step so that the sheet transport surface is lower than the sheet transport surface of the sheet transport conveyor. Stopping means at the supply end of the sheet discharge conveyor to temporarily stop the sheets when dividing them into batches A sheet stacker that is provided with. 2. The sheet stacker according to claim 1, further comprising, instead of the stopping means, a conveyor control means for making the sheet conveying speed of the sheet conveying conveyor slower than the sheet conveying speed of the sheet discharging conveyor when dividing the sheets into batches. A sheet stacker characterized by that. 3. The sheet conveying conveyor and the sheet discharging conveyor are fixedly arranged so as to incline with an upward slope toward the discharging end of each conveyor, and the front guide and the back guide forming the drop guide path are also fixedly arranged. 3. The sheet stacker according to claim 1, further comprising an elevating device that moves the table of the sheet stacking unit up and down with respect to the drop guide path. 4. The sheet stacker according to claim 3, wherein the inclination angle of the sheet discharging conveyor is smaller than the inclination angle of the sheet conveying conveyor.