SHEET FOLDING APPARATUS

Abstract

Buckles (b1 to b4) are each provided with a stopper (S1 to S4). A pair of uptake rollers (W, W1); (W, W2); (W2, W3); (W3, W4), to supply paper to the buckles, and a pair of discharge rollers (W, W2); (W2, W3); (W3; W4); (W4, W5), to fold the portion of the paper discharged outside the buckles, are disposed at each buckle inlet. The discharge roller for a previous buckle simultaneously functions as the uptake roller for the next buckle, and the paper is sequentially introduced into the buckles and folded into a bellows form. Stopper drive mechanisms (d1 to d4) are integrally controlled by a control unit (C). The control unit receives input for the value of the difference in length between the last folded piece and the remaining folded piece of a bellows-folded paper in which a folding error has occurred, divides the length difference by the number of buckles, and sends control instructions to slide the stoppers in the same direction as the buckle inlet (e) relative to the stopper drive mechanisms for the length obtained by division in order to make the length difference zero.

Description

TECHNICAL FIELD

The present invention relates to a sheet folding apparatus, particularly, a sheet folding apparatus which folds up a sheet like an accordion by alternating mountain and valley folds of the sheet in a direction perpendicular to a sheet feed direction.

BACKGROUND ART

In the prior art, there are some sheet folding apparatuses in which a plurality of folding roller pairs is arranged and a sheet is folded up like an accordion by the sheet being nipped between the folding roller pairs sequentially (See also, for example, Patent Documents 1 and 2).

FIG. 7 is a schematic view illustrating an configuration of such conventional sheet folding apparatus. In FIG. 7, an alphabet A designates a sheet supply unit, an alphabet B designates a sheet conveyance unit and an alphabet C designates a sheet folding unit. The sheet supply unit has a sheet supply table 1 arranged for vertical motion and supporting a sheet bundle thereon, and a roller 2 feeding the uppermost sheet P of the sheet bundle to the sheet conveyance unit B one by one. The sheet conveyance unit B has a conveyor belt 3 conveying the sheet P supplied from the sheet supply unit A to the sheet folding unit C, and a group of idle rollers 4 preventing the sheet P from lifting from the conveyor belt 3.

The sheet folding unit C has a plurality of buckles b1-b4, and each of the buckles b1-b4 is provided with a stopper S1-S4 whose positon is adjustable. Near an inlet of each of the buckles b1-b4, a pair of driven intake rollers W, W1; W, W2; W2, W3; W3, W4 is arranged opposite to each other so as to take the sheet P into the associated buckle b1-b4 and a pair of driven discharge rollers W, W2; W2, W3; W3, W4; W4, W5 is arranged opposite to each other so as to fold a portion of the sheet P exteriorly protruding from the associated buckle b1-b4.

Then a discharge roller associated with a previous buckle concurrently serves as an intake roller associated with the next buckle and thereby, the sheet P is sequentially taken into a plurality of buckles and folded like an accordion by alternating mountain and valley folds of the sheet in a direction perpendicular to a sheet feed direction depending on the number of the buckles.

In particular, when the folding operation is carried out, each of the stopper S1-S4 is fixed to a positon corresponding to a folding positon of the sheet P. Then the sheet P fed from the sheet conveyance unit B is nipped between the pair of rollers W and W1 so as to be inserted into the buckle b1. When the leading end of the sheet P collides with the stopper S1 of the buckle b1, the sheet P is deflected from the buckle b1 in the neighborhood of the inlet of the buckle b1, the deflected portion is nipped between the pair of rollers W2 and W, and the sheet P is folded to one side.

Next, the folded sheet P is inserted into the buckle b2 with its fold line in the lead. When the leading end of the folded sheet P collides with the stopper S2 of the buckle b2, the folded sheet P is deflected from the buckle b2 in the neighborhood of the inlet of the buckle b2, the deflected portion is nipped between the pair of rollers W2 and W3, and the folded sheet is further folded to the other side. Thus the sheet P is folded at two positions. Similarly, the twice folded sheet P is further folded by the buckle b3 together with the pair of rollers W2 and W3 and the pair of rollers W3 and W5, and further folded by the buckle b4 together with the rollers W3, W4 and W5.

Consequently, the sheet folded up like an accordion by alternating mountain and valley folds of the sheet in a direction perpendicular to a sheet feed direction is discharged from the apparatus.

According to this apparatus, the length of each flap of the accordion fold can be changed by adjusting the position of the stoppers S1-S4 of the buckles b1-b4. In order to obtain an evenly accordion-folded sheet (an accordion fold whose flaps have the same length), all of the stoppers S1-S4 are set in such a way that they are arranged at the same distance from the inlets of the associated buckles b1-b4.

However, a collision speed of a sheet P slightly differs from one stopper to another, and the firmness and deflection characteristics are differ from one sheet to another. Therefore, in the conventional sheet folding apparatus, there arises a folding error that causes an accordion-folded sheet whose last flap is longer or shorter than the remaining flaps.

In such case, conventionally, a difference in length between the last flap and the remaining flaps is measured, and, based on the measured value, the positions of the stoppers S1-S4 of the buckles b1-b4 are reset individually in consideration of a difference between the set value and a flap length when a sheet is actually folded. However, the work of resetting needs skill and a long time.

PRIOR ART DOCUMENTS

Patent Documents

Patent Document 1: JP 2001-88227 A

Patent Document 2: JP 3253669 B

SUMMARY OF THE INVENTION

Problems to be Solved by the Invention

It is, therefore, an object of the present invention to provide a sheet folding apparatus capable of easily resetting positions of stoppers in a short time when the folding error occurs in a process of evenly folding up a sheet like an accordion.

Means for Solving the Problems

In order to achieve the object, according to the present invention, there is provided a sheet folding apparatus which folds up a sheet like an accordion by alternating mountain and valley folds of the sheet in a direction perpendicular to a sheet feed direction, the sheet folding apparatus comprising: a sheet supply unit sequentially feeding the sheet from a sheet stack; and a sheet folding unit folding the sheet fed from the sheet supply unit in the direction perpendicular to the sheet feed direction, the sheet supply unit comprising: a shelf on which the sheet stack is placed; a conveyor belt extending between the shelf and the sheet folding unit; and a sheet feeder feeding the sheet from the sheet stack to the conveyor belt one by one, the sheet folding unit comprising: a plurality of buckles into which the sheet fed from the conveyor belt is inserted sequentially; and a stopper attached to each of the buckles so as to be slidable along the sheet feed direction, wherein, each time the sheet is inserted into the buckles, the sheet is positioned at a preset folding position by colliding with the associated stopper at the leading end thereof, the sheet folding unit further comprising: a stopper drive mechanism arranged at each of the buckles so as to move the associated stopper; a pair of driven intake rollers arranged in the neighborhood of an inlet of each of the buckles and opposed to each other so as to take the sheet in the associated buckle; and a pair of driven discharge rollers arranged in the neighborhood of the inlet of each of the buckles and opposed to each other so as to fold a portion of the sheet exteriorly protruding from the associated buckle, the discharge roller associated with a previous buckle concurrently serving as the intake roller associated with the next buckle, thereby the sheet being sequentially inserted into the buckles so as to be folded at the number of times corresponding to the number of the buckles, characterized in that the sheet folding apparatus further comprises a control unit integrally controlling the stopper drive mechanisms of the sheet folding unit, and the control unit receives an input of a difference in length between the last flap and the remaining flaps of an accordion-folded sheet accompanied with a folding error and divides the difference in length by the number of the buckles, wherein when the last flap is longer than the remaining flaps, in order to eliminate the difference in length, the control unit sends control signals to each of the stopper drive mechanisms in such a way that the associated stopper is moved in a direction away from the inlet of the associated buckle by the distance corresponding to the result of the division, and when the last flap is shorter than the remaining flaps, in order to eliminate the difference in length, the control unit sends control signals to each of the stopper drive mechanisms in such a way that the associated stopper is moved in a direction toward the inlet of the associated buckle by the distance corresponding to the result of the division.

Effect of the Invention

According to the present invention, the sheet folding apparatus comprises the control unit integrally controlling the stoppers of the buckles of the sheet folding unit, and when the folding error occurs in a process of evenly folding up a sheet like an accordion, the positions of the stoppers of the buckles are automatically reset so as to correct the folding error just by inputting to the control unit a value of a difference in length between the last flap and the remaining flaps of the accordion-folded sheet accompanied with the folding error, and thereby, it is possible to easily reset the positions of the stoppers in a short time when the folding error occurs.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view showing a configuration of a sheet folding apparatus according to an embodiment of the present invention.

FIG. 2 is an enlarged view showing a configuration of a sheet folding unit of the sheet folding apparatus shown in FIG. 1.

FIGS. 3A through 3C are perspective views showing examples of accordion fold achieved by the sheet folding apparatus shown in FIG. 1.

FIG. 4 is a view showing a screen displayed on a touch screen of the sheet folding apparatus shown in FIG. 1.

FIG. 5 is a view showing a screen displayed on the touch screen of the sheet folding apparatus shown in FIG. 1.

FIG. 6 is a view showing a screen displayed on the touch screen of the sheet folding apparatus shown in FIG. 1.

FIG. 7 is a schematic view showing a configuration of a conventional sheet folding apparatus.

BEST MODE FOR CARRYING OUT THE INVENTION

A preferred embodiment according to the present invention will be explained below with reference to the accompanying drawings. FIG. 1 is a schematic view showing a configuration of a sheet folding apparatus according to an embodiment of the present invention, and FIG. 2 is an enlarged view showing a configuration of a sheet folding unit of the sheet folding apparatus shown in FIG. 1.

Referring to FIG. 1, the sheet folding apparatus of the present invention comprises a sheet supply unit A sequentially feeding the sheet P from a sheet stack M and a sheet folding unit B folding the sheet P fed from the sheet supply unit A in the direction perpendicular to the sheet feed direction.

The sheet supply unit A comprises a vertically movable shelf 1 on which the sheet stack M is placed, a conveyor belt 2 extending between the shelf 1 and the sheet folding unit B and a sheet feeder 3 feeding the uppermost sheet P of the sheet stack M to the conveyor belt 2 one by one. In this embodiment, the sheet feeder 3 consists of a driven roller arranged above the front end of the shelf 1. In FIG. 1, the reference numeral 4 designates a group of idle rollers preventing the sheet P from lifting from the conveyor belt 3.

The sheet folding unit B comprises a plurality of buckles (in this embodiment, four buckles b1-b4) into which the sheet P fed from the conveyor belt 2 is inserted sequentially, and a stopper S1-S4 attached to each of the buckles b1-b4 so as to be slidable along the sheet feed direction. In this case, each of the buckles b1-b4 is provided with a guide rail (not shown) extending parallel to the associated buckle, and the stoppers S1-S4 are attached to the guide rails for slide movement. Each time the sheet P is inserted into the buckles b1-b4, the sheet S is positioned at a preset folding position by colliding with the associated stopper S1-S4 at the leading end thereof.

The sheet folding unit B further comprises a stopper drive mechanism d1-d4 arranged at each of the buckles b1-b4 so as to move the associated stopper S1-S4.

Referring to FIG. 2, in this embodiment, each of the stopper drive mechanisms d1-d4 consists of a threaded shaft 5 of a ball screw, a motor 6 attached to the buckle b1-b4 so as to rotate the thread shaft 5, and a nut (not shown) of the ball screw arranged at the stopper S1-S4 and engaging with the threaded shaft 5. The stopper S1-S4 is engaged with the threaded shaft 5 through the nut.

Thus the stopper S1-S4 is moved in directions toward and away from an inlet e of the associated buckle b1-b4 by clockwise and counterclockwise rotations of the motor 6.

A configuration of the stopper drive mechanism d1-d4 is not limited to this embodiment. Instead of a combination of a ball screw and a motor, for example, a combination of an endless belt extending between a pair of pulleys in a direction parallel to the buckle b1-b4 and a motor rotating one of the pulleys may be used. In this case, the stopper S1-S4 is fixed to the endless belt.

The stopper drive mechanisms d1-d4 are integrally controlled by a control unit C.

A pair of driven intake rollers W, W1; W, W2; W2, W3; W3, W4 is arranged in the neighborhood of the inlet e of each of the buckles b1-b4 and opposed to each other so as to take the sheet in the associated buckle b1-b4. A pair of driven discharge rollers W, W2; W2, W3; W3, W4; W4, W5 is also arranged in the neighborhood of the inlet e of each of the buckles b1-b4 and opposed to each other so as to fold a portion of the sheet P exteriorly protruding from the associated buckle b1-b4.

The discharge roller associated with a previous buckle concurrently serving as the intake roller associated with the next buckle, thereby the sheet P being sequentially inserted into the buckles so that mountain and valley folds of the sheet P are alternated in a direction perpendicular to the sheet feed direction at the number of times corresponding to the number of the buckles and an accordion-folded sheet is obtained.

Namely, the sheet P fed from the conveyor belt 2 of the sheet supply unit A is nipped between the pair of rollers W and W1 so as to be inserted into the buckle b1. When the leading end of the sheet P collides with the stopper S1 of the buckle b1, the sheet P is deflected from the buckle b1 in the neighborhood of the inlet of the buckle b1, the deflected portion is nipped between the pair of rollers W2 and W, and the sheet P is folded to one side (first fold).

Next, the folded sheet P is inserted into the buckle b2 with its fold line in the lead. When the leading end of the folded sheet P collides with the stopper S2 of the buckle b2, the folded sheet P is deflected from the buckle b2 in the neighborhood of the inlet of the buckle b2, the deflected portion is nipped between the pair of rollers W2 and W3, and the folded sheet is further folded to the other side (second fold).

Similarly, the twice folded sheet P is further folded by the buckle b3 together with the pair of rollers W2 and W3 and the pair of rollers W3 and W5 (third fold), and further folded by the buckle b4 together with the rollers W3, W4 and W5 (fourth fold). Then the accordion-folded sheet P is discharged from the sheet folding apparatus.

In the sheet folding apparatus according to the present invention, as shown in FIG. 3A, in order to obtain an evenly accordion-folded sheet P (an accordion fold whose flaps P1-P5 have the same length), positions of the stoppers S1-S4 of the buckles b1-b4 are preset by the control unit C (regularly, all of the stoppers S1-S4 are set in such a way that they are arranged at the same distance from the inlets of the associated buckles b1-b4).

However, a collision speed of a sheet P slightly differs from one stopper to another, and the firmness and deflection characteristics are differ from one sheet to another. Consequently, as shown in FIG. 3B, there arises a folding error that causes an accordion-folded sheet P whose last flap P5 is longer than the remaining flaps P1-P4 (L1), or an accordion-folded sheet P whose last flap P5 is shorter than the remaining flaps P1-P4 (L2).

According to the present invention, when such folding error occurs, at first, an operator measures a difference in length between the last flap P5 and the remaining flaps P1-P4 of an accordion-folded sheet P accompanied with a folding error.

Then the control unit C receives an input of the measured value of the difference of length, and divides the difference in length by the number of the buckles b1-b4 (in this embodiment, four). When the last flap P5 is longer than the remaining flaps P1-P4 (FIG. 3B), in order to eliminate the difference in length, the control unit C sends control signals to each of the stopper drive mechanisms d1-d4 in such a way that the associated stopper S1-S4 is moved in a direction away from the inlet e of the associated buckle b1-b4 by the distance corresponding to the result of the division (L1/4), and when the last flap P5 is shorter than the remaining flaps P1-P4, in order to eliminate the difference in length, the control unit C sends control signals to each of the stopper drive mechanisms d1-d4 in such a way that the associated stopper S1-S4 is moved in a direction toward the inlet e of the associated buckle b1-b4 by the distance corresponding to the result of the division.

In this case, when the input value of the difference in length cannot be divided evenly by the number of the buckles, the control unit C controls the stopper drive mechanisms d1-d4 based on a value obtained by rounding or rounding up or rounding down the result of the division.

In this embodiment, the control unit C comprises a touch screen (not shown) as an input means. A screen displayed on the touch screen for receiving an input of setting values of positions of the stoppers S1-54 is shown in FIG. 4.

In FIG. 4, the reference numeral 7a designates an entry field for the setting value of a position of the stopper S1 of the first buckle b1, and the reference numeral 7b designates an entry field for setting value of a position of the stopper S2 of the second buckle b2, and the reference numeral 7c designates an entry field for the setting value of a position of the stopper S3 of the third buckle b3, and the reference numeral 7d designates an entry field for setting value of a position of the stopper S4 of the fourth buckle b4. As the position of each of the stopper S1-S4, a distance from the inlet of the associated buckle to the stopper S1-S4 is inputted.

In FIG. 4, the same setting value (165.0 mm) is inputted in each of entry fields 7a-7d. The numeral values are inputted through a numeric keypad (not shown) as well as a pair of “+” and “−” buttons which is arranged at the right side of each of the entry fields 7a-7d.

After the input of the setting values, the sheet folding apparatus starts operating. Then when the folding error occurs, a difference in length between the last flap and the remaining flaps of the accordion-folded sheet accompanied with the folding error is measured by an operator.

Next, the display on the touch screen is switched to a display for input of the measured value as shown in FIG. 5. In FIG. 5, the reference numeral 8 designates an entry field for the measured value. When the last flap is longer than the remaining flaps of the accordion-folded sheets, the measured value (the difference in length) as positive numeric value is inputted to the entry field 8, and when the last flap is shorter than the remaining flaps, the measured value (the difference in length) as negative numeric value is inputted to the entry field 8.

In FIG. 5, the last flap is 8 mm longer than the remaining flaps and therefore, positive numeric value of “+8 mm” is inputted to the entry field 8.

Thus the measured value of “+8 mm” is inputted to the control unit C by the operator through the touch screen.

After the input of the measured value, the display on the touch screen is switched to the display for input of the setting values of positions of the stoppers again. Now the result of the division by the control unit C is 8 mm/4=2 mm and therefore, in order to move all of the stoppers S1-S4 by 2 mm in a direction away from the inlets e of the buckles b1-b4, the control unit C changes all of the setting values “165.0 mm” which have been inputted to the entry fields 7a-7d on the display to “167.0 mm”. At the same time, the control unit C sends control signals to all of the stopper drive mechanisms so as to move the stoppers based on the changed setting values, thereby the folding error is corrected.

According to the present invention, when the folding error occurs in a process of evenly folding up a sheet like an accordion, the positions of the stoppers of the buckles are automatically reset so as to correct the folding error just by inputting to the control unit a value of a difference in length between the last flap and the remaining flaps of the accordion-folded sheet accompanied with the folding error, and thereby, it is possible to easily reset the positions of the stoppers in a short time when the folding error occurs.

DESCRIPTION OF REFERENCE NUMERALS

• 1 Shelf
• 2 Conveyor belt
• 3 Sheet feeder
• 4 Group of idle rollers
• 5 Threaded shaft
• 6 Motor
• 7a-7d Entry field for setting value of a position of stopper of buckle
• A Sheet supply unit
• B Sheet folding unit
• C Control unit
• M Sheet stack
• S1-S4 Stopper
• P Sheet
• P1-P5 Flap
• W, W1; W, W2; W2, W3; W3, W4 Intake roller
• W, W2; W2, W3; W3, W4; W4, W5 Discharge roller
• b1-b4 Buckle
• d1-d4 Stopper drive mechanism
• e Inlet of buckle

Claims

1. A sheet folding apparatus which folds up a sheet like an accordion by alternating mountain and valley folds of the sheet in a direction perpendicular to a sheet feed direction, the sheet folding apparatus comprising:

a sheet supply unit sequentially feeding the sheet from a sheet stack; and

a sheet folding unit folding the sheet fed from the sheet supply unit in the direction perpendicular to the sheet feed direction,

the sheet supply unit comprising:

a shelf on which the sheet stack is placed;

a conveyor belt extending between the shelf and the sheet folding unit; and

a sheet feeder feeding the sheet from the sheet stack to the conveyor belt one by one,

the sheet folding unit comprising:

a plurality of buckles into which the sheet fed from the conveyor belt is inserted sequentially; and

a stopper attached to each of the buckles so as to be slidable along the sheet feed direction, wherein, each time the sheet is inserted into the buckles, the sheet is positioned at a preset folding position by colliding with the associated stopper at the leading end thereof,

the sheet folding unit further comprising:

a stopper drive mechanism arranged at each of the buckles so as to move the associated stopper;

a pair of driven intake rollers arranged in the neighborhood of an inlet of each of the buckles and opposed to each other so as to take the sheet in the associated buckle; and

a pair of driven discharge rollers arranged in the neighborhood of the inlet of each of the buckles and opposed to each other so as to fold a portion of the sheet exteriorly protruding from the associated buckle, the discharge roller associated with a previous buckle concurrently serving as the intake roller associated with the next buckle, thereby the sheet being sequentially inserted into the buckles so as to be folded at the number of times corresponding to the number of the buckles, characterized in that

the sheet folding apparatus further comprises a control unit integrally controlling the stopper drive mechanisms of the sheet folding unit, and

the control unit receives an input of a difference in length between the last flap and the remaining flaps of an accordion-folded sheet accompanied with a folding error and divides the difference in length by the number of the buckles, wherein

when the last flap is longer than the remaining flaps, in order to eliminate the difference in length, the control unit sends control signals to each of the stopper drive mechanisms in such a way that the associated stopper is moved in a direction away from the inlet of the associated buckle by the distance corresponding to the result of the division, and when the last flap is shorter than the remaining flaps, in order to eliminate the difference in length, the control unit sends control signals to each of the stopper drive mechanisms in such a way that the associated stopper is moved in a direction toward the inlet of the associated buckle by the distance corresponding to the result of the division.