Paper folding device

Abstract

To provide a simple and inexpensive paper folding device that is easy to operate and does not require an operator to input the paper type (thickness) in advance without increasing the complexity of the structure, and to prevent hitting sound from being made regardless of the paper type.SOLUTION: A leading edge of paper being conveyed is guided upward by a switching gate plate placed in a first guiding position, and at least once before the leading edge of the paper hits the upper surface of an upper roller, the switching gate plate is placed in the release position.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a paper folding device, and more particularly to a paper folding device suitable for a bag making machine that produces envelopes. [Background technology]

[0002] Conventionally, a paper folding device (for example, Patent Document 1) that folds media such as paper transports the paper and inserts the leading edge of the paper into a paper insertion space (divertment path), and even after the leading edge of the paper hits a stopper provided in the paper insertion space and its progress is blocked, the paper continues to be transported at its trailing edge, causing the paper to bend outside the paper insertion space and form a curved portion, which is then pinched and pulled in between a pair of rollers, and the paper is folded over to fold the medium. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-312939 [Patent Document 2] Patent Publication No. 2021-84730 Summary of the Invention [Problem to be solved by the invention]

[0004] In a folding device equipped with a stopper such as that disclosed in the aforementioned Patent Document 1, the stopper position must be adjusted to suit various folding specifications. To adjust the stopper position, the operator must manually adjust the stopper position or the device must be equipped with an automatic stopper movement mechanism. Manually adjusting the stopper position requires complicated operation and is not user-friendly. Equipping the device with an automatic stopper movement mechanism is easy to operate but expensive.

[0005] Therefore, the applicant of the present application has proposed a bag making machine equipped with a paper folding device of a novel configuration as shown in Patent Document 2, as an invention that solves the various problems of the conventional technology described above. As a result, the folding mechanism does not need to be provided with a paper insertion space (diverter path) or a stopper, so it can be configured simply and inexpensively without causing structural complexity. Furthermore, since the control means automatically adjusts the folding position to suit various folding specifications, it is possible to provide a paper folding device that is easy to operate.

[0006] However, as the applicant further advanced research and development into paper folding devices, he discovered new issues with the new paper folding device configuration proposed by the applicant (Patent Document 2), and found that there was room for further improvement in the performance of the paper folding device by solving these issues.

[0007] That is, as shown in Figure 9(a) of the present application, when the leading edge of the conveyed paper is guided upward by the switching gate plate positioned at the first guide position (inclination angle θ1), depending on the type of paper (particularly thick paper), the leading edge of the paper may strike the upper surface 871a of the upper roller, generating a noise that is unpleasant for the operator. As a countermeasure to the noise, as shown in Figure 9(b) of the present application, by increasing the inclination angle of the switching gate plate (inclination angle θ2) so that the leading edge of the paper does not strike the upper surface of the upper roller, the noise can be prevented. However, if the inclination angle is kept the same, another problem occurs, in that the paper cannot stably move up the inclination of the switching gate plate, particularly when thin paper is used, and the switching gate plate buckles. To solve both of the problems mentioned above, the inclination angle of the switching gate plate must be increased (inclination angle θ2) when using thick paper and decreased (inclination angle θ1) when using thin paper. Regardless of the type of paper (thick paper, thin paper), there is almost no common range of inclination angles that can solve both problems at once.

[0008] The present invention has been made in view of these newly discovered new technical problems, In view of the problems with the conventional paper folding devices described above, the object of the present invention is to provide a paper folding device that can be constructed simply and inexpensively without complicating the structure, that is easy to operate, and that does not require the operator to input the paper type (thickness) in advance, and that can prevent the generation of impact noise regardless of the paper type. [Means for solving the problem]

[0009] In order to achieve the above object, the invention described in claim 1 is a paper folding device that folds flat paper while transporting it along a paper transport surface, and includes a first pair of transport rollers arranged upstream in the paper transport direction, a second pair of transport rollers arranged downstream in the paper transport direction, a switchover gate plate installed on the paper transport surface between both pairs of rollers, a folding plate arranged above the switchover gate plate, and control means for controlling the operation of the entire device, wherein the switchover gate plate interferes with the paper being transported and is switchable between a first guide position where it guides the paper upward so that the leading edge of the paper passes over the upper surface of the upper roller of the second pair of transport rollers, a separating position where it guides the paper upward so that the leading edge of the paper moves away from the upper surface of the upper roller, and a second guide position where it guides the paper along the paper transport surface toward the nip portion of the second pair of transport rollers, and the folding plate is configured to be movable up and down while remaining approximately horizontal, and the switchover gate plate arranged at the second guide position is and a retracted position where the switching gate plate is retracted at a predetermined distance from the switching gate plate, and the control means uses the switching gate plate arranged at the first guiding position to guide the leading edge of the paper being conveyed upward, and at least before the leading edge of the paper strikes the upper surface of the upper roller, the control means temporarily positions the switching gate plate at a retracted position to prevent the leading edge of the paper from striking the upper surface of the upper roller, and then returns the switching gate plate to the first guiding position, guiding the leading edge of the paper to pass a predetermined distance over the upper surface of the upper roller, and then switches the switching gate plate to the second guiding position, and then lowers the folding plate arranged at the retracted position in a substantially horizontal state to a folding position so as to sandwich the paper on the switching gate plate, thereby controlling the leading edge of the paper to fold back along the surface of the upper roller.

[0010] The invention described in claim 2 is characterized in that, in the paper folding device described in claim 1, the timing at which the switching gate plate is returned from the separation position to the first guiding position is the timing at which, assuming that the switching gate plate is returned from the separation position to the first guiding position while guiding the leading edge of the paper upward at the separation position, the position of the leading edge of the paper returned to the first guiding position passes at least the intersection position where an imaginary extension line of the upper surface of the switching gate plate intersects with the upper surface of the upper roller.

[0011] The invention described in claim 3 is characterized in that, in the paper folding device described in claim 1 or claim 2, the inclination angle of the switching gate plate at the first guide position is set to an angle that prevents buckling even if the type of paper guided upward on the switching gate plate is thin paper.

[0012] The invention described in claim 4 is characterized in that, in the paper folding device described in claim 1 or claim 2, as a countermeasure against impact noise, even if the type of paper is cardboard, the switching gate plate is switched from the first guiding position to the away position, thereby preventing the leading end of the paper from hitting the upper surface of the upper roller and preventing the generation of impact noise.

[0013] The invention described in claim 5 is characterized in that, in the paper folding device described in claim 1 or claim 2, after the folding plate has lowered to fold the leading edge of the paper, the control means further controls the first pair of conveying rollers to convey the folded leading edge portion of the paper after the leading edge of the paper has been folded toward the nip portion of the second pair of conveying rollers, and controls the nip portion of the second pair of conveying rollers to sandwich and convey the folded leading edge portion of the paper, thereby pressing and folding the folded leading edge portion of the paper.

[0014] The invention described in claim 6 is characterized in that, in the paper folding device described in claim 1 or claim 2, a crease processing section is further provided upstream of the first conveying roller pair in the paper conveying direction, and the crease processing section is configured to form a crease in advance at the fold when folding the flat paper.

[0015] The invention described in claim 7 is a bag making machine characterized in that, in the paper folding device described in claim 1 or claim 2, the proximity distance between the switching gate plate arranged in the second guiding position and the folding plate arranged in the folding position is configured so that at least a gap large enough to transport the paper is secured between the folding plate and the switching gate plate. [Effects of the Invention]

[0016] According to the invention described in claim 1, the control means uses a switching gate plate positioned at the first guide position to guide the leading edge of the paper being transported upward, and by temporarily positioning the switching gate plate at the away position at least before the leading edge of the paper hits the upper surface of the upper roller, the leading edge of the paper is prevented from hitting the upper surface of the upper roller and then returned to the first guide position, so that even when thick paper is used, it is possible to effectively prevent the leading edge of the paper from hitting the upper surface of the upper roller and making a noise.

[0017] According to the invention of claim 2, the timing for returning the switching gate plate from the separation position to the first guiding position is set so that, while the leading edge of the paper is being guided upward at the separation position, if we assume that the switching gate plate is returned from the separation position to the first guiding position, the position of the leading edge of the paper returned to the first guiding position passes at least the position of the intersection where an imaginary extension of the top surface of the switching gate plate intersects with the upper surface of the upper roller. This makes it possible to reliably prevent the leading edge of the paper from hitting the upper surface of the upper roller and making a sound, even when using thick paper.

[0018] According to the invention of claim 3, the inclination angle of the switching gate plate in the first guide position is set to an angle that will not buckle even if the paper guided upward on the switching gate plate is thin paper, so that the operator does not need to input the paper type (thickness) in advance, providing a paper folding device with good operability. In addition, the generation of impact noise can be prevented regardless of the paper type.

[0019] According to the invention described in claim 4, as a measure against impact noise, even if the type of paper is cardboard, the switching gate plate is switched from the first guiding position to the separation position, thereby preventing the leading edge of the paper from hitting the upper surface of the upper roller and preventing the generation of impact noise.

[0020] According to the invention of claim 5, after folding back the leading edge of the paper by lowering the folding plate, The folded-back leading edge of the paper is controlled so as to be pressed and folded by the nip portion of the second conveying roller pair, so that the paper can be reliably folded.

[0021] According to the invention of claim 6, a crease processing section is further provided on the upstream side of the first conveying roller pair in the paper conveying direction, and the crease processing section is configured to form a crease in advance at the fold line when folding the flat paper to create a fold starting point, thereby enabling neat and precise folding and suppressing print cracks that occur when folding the paper.

[0022] According to the invention described in claim 7, after the leading edge of the paper is folded back by lowering the folding plate, the folded leading edge of the paper is guided and transported in the gap between the nearby switching gate plate and the folding plate, so that the paper can be reliably delivered to the pressing processing section by the nip section of the next transport roller pair without wrinkles or the like occurring. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a schematic overall configuration diagram of a bag making machine according to a first embodiment of the present invention; [Figure 2] 2 is a plan view showing the state of paper processed by the bag making machine of FIG. 1. FIG. [Figure 3] 3 is a plan view showing the state in which the paper in FIG. 2 has been folded. FIG. [Figure 4] FIG. 1 is a perspective view showing a Western-style envelope in the middle of being produced. [Figure 5] 10A and 10B are diagrams showing how the paper is processed at the second folding section. [Figure 6] FIG. 6 is a diagram showing the state of processing of paper following FIG. 5. [Figure 7] FIG. 7 is a diagram showing the state of processing of paper following FIG. 6. [Figure 8] FIG. 8 is a diagram showing the state of processing of paper following FIG. 7. [Figure 9] 10A and 10B are diagrams showing how the paper is processed at the second folding section. [Figure 10] 10A and 10B are diagrams showing how the paper is processed at the second folding section. [Figure 11] 10A and 10B are diagrams showing how the paper is processed at the second folding section. [Figure 12] 10A and 10B are diagrams showing the state before and after folding back the flap at the first folding portion. [Figure 13] FIG. 10 is a diagram showing a drive mechanism for the folding plates in the second folding unit. [Figure 14] FIG. 10 is a diagram showing a drive mechanism for the folding plates in the second folding unit. [Figure 15] FIG. 10 is a diagram showing a drive mechanism for a switching gate plate in the second folding section. [Figure 16] FIG. 10 is a diagram showing a drive mechanism for a switching gate plate in the second folding section. DETAILED DESCRIPTION OF THE INVENTION

[0024] Figure 1 shows an embodiment of a bag making machine 10 that employs a paper folding device (second folding unit 6) of the present invention. Figure 1 is an overall configuration diagram of the bag making machine 10. The bag making machine 10 includes, in order from the upstream side in the conveying direction, a paper feed unit 1, a first crease processing unit 2, a second crease processing unit 4, a first folding unit 3, a glue application unit 5, a second folding unit 6, and a paper discharge unit 7 in a device main body 10A.

[0025] A typical "Western-style envelope" is a horizontally long rectangle with a sealing opening formed on the long side. When making a Western-style envelope using a bag making machine 10, glue is applied to folded-over sections 103 on both sides of a rear surface 102 of a sheet of paper 100, and the front surface 101 is folded over and pressed against the folded-over sections 103, as shown in Figure 4.

[0026] Specifically, the bag making machine 10 produces Western-style envelopes 90 by processing flat paper 100 shown in Figure 2(a) as shown in Figures 2(b) and 2(c) while transporting it in the F direction.

[0027] The sheet of paper 100 comprises a front surface 101, a rear surface 102, glue substitute pieces 103 extending from both sides of the rear surface 102, and a rearmost surface 104. As shown in FIG. 2(b), the sheet of paper 100 is folded at a first fold 111 which is the boundary between the rear surface 102 and the piece 103, and then as shown in FIG. 2(c), the sheet of paper 100 is folded at a second fold 112 which is the boundary between the front surface 101 and the rear surface 102. Glue is applied to the surface of the piece 103 folded back at the first fold 111. Then, the front surface 101 folded back at the second fold 112 has both edges joined to the piece 103. The first fold 111 is aligned with the conveyance direction. The second fold 112 is aligned with the direction perpendicular to the conveyance direction (i.e., the width direction).

[0028] The finished product may be the Western-style envelope 90 shown in Fig. 2(c), but the Western-style envelope 90 shown in Fig. 2(c) may also be processed as shown in Fig. 3 while being conveyed in the F' direction, so that the rearmost face 104 is further folded at a third fold 113, which is the boundary between the rear face 102 and the rearmost face 104. With this configuration, after the contents are inserted into the envelope, when sealing it with tape or glue, the crease will allow the rearmost face 104 to be neatly sealed to the folded-back front face 101.

[0029] [Paper feed section 1] The paper feed section 1 has an air suction belt type air paper feed unit 12, an elevator type paper feed tray 11 that rises and falls depending on the amount of paper loaded, and a transport roller 81 that transports the paper sent out by the air paper feed unit 12 further downstream in the transport direction. Also, the air paper feed unit 12 is provided with a sensor 22 that detects when the topmost sheet of paper loaded on the paper feed tray 11 is sucked onto the underside of the air paper feed unit 12, and a sensor 21 that detects the uppermost position of the topmost sheet of paper loaded on the paper feed tray 11.

[0030] In addition to conveying roller 81, bag making machine 10 is equipped with seven other conveying roller pairs 82, 83, 84, 85, 86, 87, and 88. The seven conveying roller pairs form conveying surface 200 along which paper 100 is conveyed, and conveying surface 200 is flush with the paper from air paper feed unit 12 to conveying roller pair 88. Also, sensors 23, 24, 25, 26, 27, and 28 are arranged on conveying surface 200 along which paper is conveyed, and these sensors detect the passage of paper at each position (detect double feed). Each sensor is, for example, an optical transmission sensor.

[0031] [First crease processing part 2] 1, the first crease processing unit 2 is composed of an upper mold with a convex upper portion and a lower mold with a concave lower portion, and is configured to form horizontal creases in the direction perpendicular to the paper conveyance direction as the second fold 112 and the third fold 113 of the paper 100. A known mechanism can be used as the crease processing unit 2. [Second crease processing part 4] 1, the second crease processing unit 4 is composed of an upper blade with a round crease blade having a convex portion formed on the outer periphery, and a lower blade with a round crease blade having a concave portion formed on the outer periphery, and is installed at two locations in the width direction perpendicular to the conveyance direction, so as to form vertical creases along the paper conveyance direction at the first folds 111 (two locations) of the paper 100. A known mechanism can be used as the first crease processing unit 4.

[0032] [First fold 3] The first folding section 3 is made up of a pair of folding devices 3a, 3b arranged opposite each other on either side of the width direction perpendicular to the paper conveyance direction. Each folding device 3a, 3b has a flap 32 that rotates around a rotation shaft 31 along the conveyance direction, and by rotating the flap 32 as shown in Figure 12(a), one side 103 of the paper 100 placed on the flap 32 positioned on the outer side in the width direction can be folded inward so as to match the surface of the rear surface 102, as shown in Figure 12(b).

[0033] [Glue application section 5] The glue application unit 5 is made up of a pair of application devices 5a and 5b arranged opposite each other on both sides in the width direction. The application devices 5a and 5b have a symmetrical configuration.

[0034] The application devices 5a and 5b each have a nozzle section, a position setting mechanism, and a vertical drive mechanism (not shown). The nozzle section is designed to apply glue to the paper being transported at a predetermined timing.

[0035] [Second fold 6] The second folding section 6 is a paper folding device that folds flat paper 100 while transporting it along a transport surface 200, and is equipped with a first pair of transport rollers 86 arranged upstream in the paper transport direction, a second pair of transport rollers 87 arranged downstream in the paper transport direction, a switching gate plate 63 installed between the two roller pairs, and a folding plate 62 arranged above the switching gate plate 63.

[0036] The switching gate plate 63 is switchable between a first guide position where it interferes with the transported paper 100 and guides the leading edge of the paper 100 upward so that it passes over the upper surface of the upper roller 871 of the second transport roller pair 87, and a second guide position where it guides the paper 100 in a substantially horizontal direction toward the nip portion 873 of the second transport roller pair 87. The folding plate 62 is configured to be movable in the vertical direction while remaining in a substantially horizontal state, and is switchable between a folding position close to the switching gate plate 63 located at the second guide position, and a retracted position where it retracts at a predetermined distance from the switching gate plate.

[0037] The drive mechanisms 64 and 65 for the switching gate plate 63 and the folding plate 62 will be described below.

[0038] The switching gate plate 63 is selectively positioned at the first guide position or the second guide position as shown in Figures 15 and 16. Figure 15 shows the switching gate plate 63 in the second guide position, and Figure 16 shows the switching gate plate 63 in the first guide position.

[0039] In Fig. 15, Fig. 15(a) is a front view seen from the front in the paper transport direction, and Fig. 15(b) is a cross-sectional view seen from direction C in Fig. 15(a). Also, in Fig. 16, Fig. 16(a) is a front view seen from the front in the paper transport direction, and Fig. 16(b) is a cross-sectional view seen from direction D in Fig. 16(a).

[0040] 15 and 16, the drive mechanism 64 of the switching gate plate 63 operates as follows. That is, when the motor 641 operates, the second pulley 644 rotates via the first pulley 642 and the transmission belt 643. Since the support shaft 631 of the switching gate plate 63 is connected to the second pulley 644, when the second pulley 644 rotates, the switching gate plate 63 rotates. Note that the angle of rotation of the switching gate plate 63 is determined by detecting both edges of the light-shielding plate 66 attached to the support shaft 631 of the switching gate plate 63 with the first detection means 67, so that the switching gate plate 63 can be selectively positioned at the first guide position or the second guide position.

[0041] In addition to the first and second guide positions, the switching gate plate 63 also has a separation position (see 63b in FIG. 11(a)) which is used as a countermeasure against noise, that is, noise that occurs when the leading edge of the paper 100 hits the upper surface of the upper roller 871 of the second conveying roller pair, even when cardboard is used. Regarding the rotation angle of the switching gate plate 63 at the separated position, for example, after one edge of the light blocking plate 66 is detected by the first detection means 67, the switching gate plate 63 can be selectively positioned at the separated position by counting a predetermined number of steps of the motor 641 (stepping motor). Details of the above-mentioned measures against impact noise will be described later.

[0042] The folding plate 62 is selectively placed in the above-mentioned folding position and the retracted position as shown in Figures 13 and 14. Figure 13 shows the folding plate 62 in the retracted position, and Figure 14 shows the folding plate 62 in the folded position.

[0043] In Fig. 13, Fig. 13(a) is a front view seen from the front in the paper transport direction, and Fig. 13(b) is a cross-sectional view seen from direction A in Fig. 13(a). Also, in Fig. 14, Fig. 14(a) is a front view seen from the front in the paper transport direction, and Fig. 14(b) is a cross-sectional view seen from direction B in Fig. 14(a).

[0044] As shown in Figures 13 and 14, the drive mechanism 65 for the folding plate 62 operates as follows. That is, when the motor 651 operates, a drive gear (not shown) attached to the drive shaft of the motor 651 rotates, causing an interlocking gear 655 engaged with the drive gear to rotate. A second link member 654 is fixed at its base to the rotation shaft of the interlocking gear 655 so that it can rotate, and one end of a first link member 653 is attached to its free end. A pinion 652 is attached to the other end of the first link member 653, and the pinion 652 meshes with a rack 656 that is stationary. Therefore, the first link member 653 converts the rotational motion of the second link member 654 into linear motion (reciprocating motion) of the pinion 652 on the rack 656. A folding plate 62 is attached to the rotation shaft of the pinion 652, and the folding plate 62 moves up and down (reciprocates) along the elongated hole 657 integrally with the linear motion (reciprocating motion) of the pinion 652. Furthermore, the vertical position of the folding plate 62 can be selectively positioned between the folding position and the retracted position by detecting both edges of a light-shielding plate (not shown) attached to the rotating shaft of the interlocking gear 655 using a second detection means 68.

[0045] [Pressure unit 8] The pressure applying section 8 is composed of an upper die 8a that can move up and down and a fixed lower die 8b, and by sandwiching the folded portion of the paper 100 that has been folded in the second folding section 6 between the upper die and the lower die, further pressure is applied to make the folded portion stronger.

[0046] [Paper output section 7] The paper discharge section 7 has a pair of conveying rollers 88 and a paper discharge tray 71. The pair of conveying rollers 88 is provided to operate as a discharge roller. Specifically, as shown in FIG. 1, the pair of conveying rollers 88 is disposed near the second pair of conveying rollers 87 of the second folding section 6 and downstream in the conveying direction. The paper discharge tray 71 is inclined obliquely upward from a position below the conveying surface 200 and downstream in the conveying direction.

[0047] Next, the operation of the bag making machine 10 having the above-described configuration will be described.

[0048] First, the paper 100 shown in Fig. 2 is placed on the paper feed tray 11. At this time, the front surface portion 101 is positioned downstream in the conveying direction. Then, a switch (not shown) is turned on to start operation.

[0049] (1) The topmost sheet 100 on the sheet feed tray 11 is sent toward the pair of conveying rollers 81 while being attracted to the air suction belt in the air sheet feed unit 12. After the sheet 100 is handed over to the pair of conveying rollers 81, the pair of conveying rollers 81 further conveys the sheet 100 downstream in the conveying direction. The sheet then passes through the first crease processing unit 2. At this time, the first crease processing unit 2 is activated, and creases are formed at the second fold 112 and the third fold 113 of the sheet 100. This makes it easier for the front surface 101 to be folded back toward the rear surface 102. Also, it makes it easier for the rearmost surface 104 to be folded back toward the folded front surface 101.

[0050] (2) The paper sheet 100 conveyed from the first crease processing unit 2 passes through the second crease processing unit 4. At this time, the first folds 111 (two locations on the left and right in the width direction) of the paper sheet 100 are located directly below the crease blades (round blades) of the second crease processing unit 4, which are installed in two locations in the width direction perpendicular to the conveyance direction. The second crease processing unit 4 then operates to form a crease in the first fold 111. This makes it easier for the pieces 103 (two locations on the left and right in the width direction) to fold inward.

[0051] (3) The sheet of paper 100 on which the crease has been formed by the second crease processing unit 4 stops in the first folding unit 3. At this time, the flaps 32 of the folding devices 3a and 3b of the first folding unit 3 are positioned on the outer sides of the sheet of paper 100 in the width direction, and both side portions 103 of the sheet of paper 100 rest on the flaps 32 (FIG. 12(a)). Note that in FIG. 12, the sheet of paper 100 is conveyed from the front to the back side in the drawing. Next, the flaps 32 rotate toward the inner lower guide plate 33, thereby folding the side portions 103 inward along the creased first fold 111 to align them with the surface of the rear surface portion 102 (FIG. 12(b)). Thereafter, the flaps 32 rotate in a direction away from the outer lower guide plate 33. Then, the sheet of paper 100 with the folded side portions 103 is conveyed downstream in the conveying direction by the conveying roller pair 85. The flaps 32 that have rotated outward are maintained in that state until the next sheet of paper 100 arrives. Note that, with the flaps 32 rotated inward, the sheet of paper 100 with its folded portion 103 being transported downstream in the transport direction may be operated so that the flaps 32 rotate outward before the next sheet of paper 100 arrives.

[0052] (4) The sheet 100 with the folded-back edge 103 is transported downstream in the transport direction by the transport roller pair 85 and passes through the glue application unit 5. In the glue application unit 5, when the folded-back edge 103 of the sheet 100 begins to pass, the nozzle units 5a and 5b, which are installed at two locations in the width direction perpendicular to the transport direction, move downward and contact the surface of the edge 103. When the edge 103 finishes passing, the nozzle units 5a and 5b move upward and separate from the surface of the edge 103. This causes glue to be applied to the surface of the folded-back edge 103. The folded-back edge 103 passes through the nozzle units 5a and 5b while being pressed by the transport roller pair 85, which is located upstream of the nozzle units 5a and 5b in the transport direction. This allows the nozzle units 5a and 5b to stably apply glue.

[0053] (Paper processing in the second folding section 6) The second folding unit 6 is a folding device that folds a flat sheet of paper 100 while transporting it along a transport surface 200, and includes a first transport roller pair 86 arranged upstream in the paper transport direction, a second transport roller pair 87 arranged downstream in the paper transport direction, a switching gate plate 63 installed on the paper transport surface 200 between the first and second roller pairs, a folding plate 62 arranged opposite the switching gate plate 63, and a control means (not shown) that controls the operation of the entire device.

[0054] The switching gate plate 63 is switchable between a first guide position where it interferes with the transported paper 100, bending the paper transport direction outward from the paper transport surface 200, and guiding the leading edge of the paper 100 toward one roller surface of the second transport roller pair 87, and a second guide position where it guides the paper 100 along the paper transport surface 200 toward the nip portion 873 of the second transport roller pair 87.

[0055] The folding plate 62 is configured to be movable toward the switching gate plate 63 while remaining in a substantially horizontal state, and is switchable between a folding position in which it is close to the switching gate plate 63 disposed in the second guide position, and a retracted position in which it is retracted at a predetermined distance from the switching gate plate 63,

[0056] The control means uses the switching gate plate 63 arranged in the first guide position to guide the leading edge of the paper 100 being transported so that it passes a predetermined distance toward one of the roller surfaces of the second conveying roller pair 87, then switches the switching gate plate 63 to the second guide position, and then controls the leading edge of the paper 100 to be folded back along one of the roller surfaces of the second conveying roller pair 87 by lowering the folding plate 62 arranged in the retracted position in an approximately horizontal state so as to sandwich the paper 100 on the switching gate plate 63.

[0057] Specifically, as an example, the processing is performed sequentially as shown in (5-1) to (5-4) below.

[0058] (5-1) The sheet of paper 100, with glue applied to the one side 103, is conveyed by the conveying roller pair 85 to the second folding section 6 (in the direction F). At this time, the switching gate plate 63 is set to the first guide position, facing upward toward the second conveying roller pair 87. Therefore, as shown in FIG. 5, the sheet of paper 100 is guided upward by the switching gate plate 63 so that the leading edge of the sheet of paper 100 passes over the upper surface of the upper roller 871 of the second conveying roller pair 87. When the position of the second fold 112 of the sheet of paper 100 reaches the folding position (directly below the end 621 of the folding plate 62), the conveyance is temporarily stopped. Alternatively, the conveyance may be temporarily stopped when the leading edge of the sheet of paper 100 passes over the upper surface of the upper roller 871 by a predetermined distance. Note that, although FIG. 5 shows a gap between the sheet of paper 100 and the upper roller 871, the lower surface of the sheet of paper 100 typically rubs against the upper surface of the upper roller 871 as it passes through to the stopping position. During this time, the folding plate 62 maintains its retracted position.

[0059] Furthermore, the upper roller 861 of the first conveying roller pair 86 is set to a width dimension that does not contact the surface of the side portion 103, so the glue applied to the side portion 103 of the paper 100 in the glue application section 5 mentioned above does not adhere to the first conveying roller pair 86.

[0060] (5-2) Next, as shown in FIG. 6, the folding plate 62 is kept in the retracted position, and the switching gate plate 63 is moved to the second guide position (substantially horizontal position).

[0061] (5-3) Next, as shown in FIG. 7, folding plate 62, which is disposed in the retracted position, is lowered in a substantially horizontal state to the folding position so as to sandwich sheet 100 on switching gate plate 63, thereby folding back front surface 101 of sheet 100 from second fold 112 along the surface of upper roller 871 of second conveying roller pair 87. At this time, the distance between switching gate plate 63 and folding plate 62 after lowering is configured to ensure at least a gap large enough for the sheet to be conveyed between folding plate 62 and switching gate plate 63. For example, a gap of approximately 1 mm is ensured.

[0062] As a result, the folding mechanism does not require a paper insertion space (a branch path) or a stopper, making it possible to construct a simple and inexpensive device without complicating the structure. Furthermore, the control means automatically adjusts the folding position to suit various folding specifications, providing a paper folding device with good operability. Furthermore, the folded-back portion is prevented from wrinkling, and even during folding, glue does not adhere to the inside of the folding mechanism, such as the stopper, which could adversely affect the quality of the finished product.

[0063] (5-4) Next, as shown in FIG. 8 , the folding plate 62 descends to fold the front surface 101 of the sheet 100. The first conveying roller pair 86 then conveys the folded-back leading edge 105 of the sheet toward the nip 873 of the second conveying roller pair 87. The nip 873 of the second conveying roller pair 87 then sandwiches the folded-back leading edge 105 and conveys the sheet in the F direction, thereby pressing and folding the folded-back leading edge 105. The entire front surface 101 is then folded back onto the surface of the rear surface 102, with both edges of the front surface 101 joined to the tabs 103. This completes the Western-style envelope 90. The sheet 100 continues to be conveyed in the F direction until the rearmost surface 104 of the sheet 100 passes through the nip 863 of the first conveying roller pair 86 by a predetermined distance. At this time, the paper 100 is transported (while being guided by both plates) through the gap between the folding plate 62 and the switching gate plate 63. This allows the paper 100 to be reliably delivered to the pressing section by the nip section 873 of the second transport roller pair 87 at the next stage without causing wrinkles or the like.

[0064] According to the above, after the leading edge of the paper is folded back by lowering the folding plate, the folded leading edge of the paper is pressed and folded by the nip portion 873 of the second conveying roller pair 87, so that the paper can be reliably folded.

[0065] Furthermore, a crease processing unit 2 is provided upstream of the first conveying roller pair 86 in the paper conveying direction, and the crease processing unit 2 forms creases in advance at the folds (second fold 112, third fold 113) when folding the flat paper 100 to create folding starting points, allowing for neat and precise folding. It also makes it possible to suppress print cracks that occur when folding the paper.

[0066] (Countermeasures against buckling and impact noise of the paper 100 at the second folding section 6) Next, we will explain measures to prevent buckling and impact noise of the paper sheet 100 in the second folding section 6. The general flow of the processing order of the paper sheet 100 in the second folding section 6 has been explained above in (5-1) to (5-4), but the following explanation will further expand on the operation of (5-1) as a measure to prevent buckling and impact noise of the paper sheet 100.

[0067] As shown in Figure 9(a), when the switching gate plate 63 positioned at the first guide position 63a (inclination angle θ1) guides the leading edge of the conveyed paper 100 upward, depending on the type of paper 100 (particularly thick paper), the leading edge 100' of the paper 100 may strike the upper surface 871a of the upper roller 871, generating a noise that is unpleasant to the operator. As a countermeasure to the noise, as shown in Figure 9(b), by increasing the inclination angle of the switching gate plate at the separation position 63b (inclination angle θ2) so that the leading edge 100' of the paper 100 does not strike the upper surface 871a of the upper roller 871, the noise can be prevented. However, if the inclination angle is kept the same, another problem occurs, particularly when thin paper is used, in that the paper cannot stably move up the inclination of the switching gate plate and buckles.

[0068] To solve both of the problems described above, the inclination angle of the switching gate plate needs to be increased (inclination angle θ2) when using thick paper to prevent impact noise, and needs to be decreased (inclination angle θ1) when using thin paper to prevent buckling. Regardless of the type of paper 100 (thick paper, thin paper), there is almost no common range of inclination angles that can solve both problems at once.

[0069] Therefore, by controlling as follows, it is possible to prevent the buckling of the paper 100 and the generation of the impact noise by common control, without the operator having to input the type (thickness) of the paper in advance. The basic position of the switching gate plate 63 is the first guide position 63a, and the inclination angle of the switching gate plate 63 at the first guide position 63a is set to an angle (θ1 in FIG. 10(a)) that will not buckle even if the type of paper 100 guided upward on the switching gate plate 63 is thin paper. Also, as a countermeasure against impact noise, even if the type of paper 100 is thick paper, by temporarily switching the switching gate plate 63 from the first guide position 63a to the separated position 63b (θ2 in FIG. 10(b)), it is possible to prevent the leading edge 100' of the paper 100 from hitting the upper surface 871a of the upper roller, thereby preventing the generation of impact noise.

[0070] In detail, the bag making machine 10 is equipped with a control means for controlling the operation of the entire device, and as shown in Figure 11(a), the control means uses a switching gate plate 63 arranged at a first guide position 63a to guide the leading end portion of the paper 100 being transported upward, and controls the switching gate plate 63 to be temporarily arranged at a separation position 63b at least before the leading end portion 100' of the paper 100 hits the upper surface 871a of the upper roller 871, thereby preventing the leading end portion 100' of the paper 100 from hitting the upper surface 871a of the upper roller, and then returns to the first guide position 63a. Thereafter, as described above in (5-2) to (5-4), the leading edge of the paper 100 is guided to pass a predetermined distance over the upper surface of the upper roller 871, and then the switching gate plate 63 is switched to the second guiding position (see Figure 6), and then the folding plate 62, which is positioned in the retracted position, is lowered in an approximately horizontal state to the folding position so as to sandwich the paper 100 on the switching gate plate 63, thereby controlling the leading edge of the paper 100 to be folded back along the surface of the upper roller 871.

[0071] This effectively prevents the generation of a sound caused by the leading edge 100' of the paper 100 hitting the upper surface 871a of the upper roller 871, even when thick paper is used. Furthermore, as a measure against the sound, the transport of the paper 100 continues without stopping even when the switching gate plate 63 is switched from the first guiding position 63a to the separating position 63b. Therefore, the processing speed is not affected.

[0072] Specifically, the timing for returning the switching gate plate 63 from the separation position 63b to the first guiding position 63a is the timing (e.g., 871b in Figure 11(b)) when, assuming that the switching gate plate 63 is returned from the separation position 63b to the first guiding position 63a while guiding the leading edge of the paper upward at the separation position 63b (63b in Figure 11(a)), the position of the leading edge 100' of the paper 100 (dotted line in Figure 11(b)) returned to the first guiding position 63a passes at least the position (inclination angle θ1) of the intersection 871a where the imaginary extension line of the upper surface of the switching gate plate 63 (dashed line in Figure 11(b)) intersects with the upper surface of the upper roller 871.

[0073] This makes it possible to reliably prevent the generation of a sound caused by the leading edge 100' of the paper sheet 100 hitting the upper surface 871a of the upper roller 871, even when thick paper is used. That is, as shown by the dashed line in Figure 11(b), the leading edge of the paper sheet 100 is inclined at least a certain amount relative to the upper surface of the upper roller 871 (inclination angle θ3), and this prevents the leading edge 100' of the paper sheet 100 from directly hitting the upper surface of the upper roller 871, thereby reliably preventing the generation of a sound caused by the hitting.

[0074] (6) Next, the envelope 90 is transported from the second folding section 6 to the pressure section 8, where the folded sections 105 and 106 are sequentially sandwiched and pressed between the upper die 8a and the lower die 8b of the pressure section 8. This strengthens the folded sections 105 and 106. After being pressed, the envelope 90 is transported by the pair of transport rollers 88 toward the paper discharge section 7 and discharged onto the paper discharge tray 71.

[0075] In one embodiment, the paper folding device (second folding section 6) of the present invention has been described as being used as a paper folding mechanism in a bag making machine 10 that produces Western-style envelopes, but it can also be implemented as a paper folding machine (paper folding device) that simply folds paper.

[0076] It is clear that the present invention is not limited to the present embodiment, and that within the scope of the technical concept of the present invention, the present embodiment may be modified as appropriate in addition to the modifications suggested in the present embodiment. Furthermore, the number, position, shape, etc. of the components are not limited to the present embodiment, and the number, position, shape, etc. of the components may be any number, position, shape, etc. suitable for implementing the present invention. [Explanation of symbols]

[0077] F Conveying direction F´ conveying direction θ1 Tilt angle θ2 Tilt angle 2. First crease processing section 3 First fold 4 Second crease processing section 5 Glue application section 6 Second fold 7 Paper output section 8 Pressurizing section 10 Bag making machine 10A Device body 62 Folding Plate 63 Switching gate plate 63a First guide position 63b Detachment position 64 Drive mechanism 65 Drive mechanism 86 First conveying roller pair 87 Second conveying roller pair 100 sheets 100´ paper 101 Front section 102 Rear part 103 Glue substitute piece 104 Last part 105 Folded section 106 Folded section 111 First fold 112 Second fold 113 Third fold 631 Support shaft 871 Upper roller 871a Upper surface (contact point)

Claims

1. A paper folding device that folds flat paper while transporting it along a paper transport surface, comprising: a first pair of transport rollers arranged upstream in the paper transport direction; a second pair of transport rollers arranged downstream in the paper transport direction; a switching gate plate installed on the paper transport surface between the first and second pairs of rollers; a folding plate arranged above the switching gate plate; and a control means for controlling the operation of the entire device. the switching gate plate is switchable among a first guide position where it interferes with the transported paper and guides the leading edge of the paper upward so that it passes over the upper surface of the upper roller of the second transport roller pair, a separating position where it guides the leading edge of the paper upward so that it moves away from the upper surface of the upper roller, and a second guide position where it guides the paper along the paper transport surface toward the nip portion of the second transport roller pair, The folding plate is configured to be movable in the vertical direction while remaining in a substantially horizontal state, and is switchable between a folding position in which it abuts or is close to the switching gate plate disposed at the second guide position, and a retracted position in which it is retracted at a predetermined interval from the switching gate plate, the control means uses the switching gate plate, which is positioned at the first guiding position, to guide the leading edge of the paper being conveyed upward, and at least before the leading edge of the paper strikes the upper surface of the upper roller, temporarily positions the switching gate plate at a separation position to prevent the leading edge of the paper from striking the upper surface of the upper roller, and then returns the switching gate plate to the first guiding position, guiding the leading edge of the paper so that it passes a predetermined amount over the upper surface of the upper roller, and then switches the switching gate plate to the second guiding position, and then lowers the folding plate, which is positioned at the retracted position, to a folding position in an approximately horizontal state so as to sandwich the paper on the switching gate plate, thereby controlling the leading edge of the paper to be folded back along the surface of the upper roller.

2. 2. The paper folding device according to claim 1, wherein the timing at which the switching gate plate is returned from the separation position to the first guiding position is the timing at which, assuming that the switching gate plate is returned from the separation position to the first guiding position while guiding the leading edge of the paper upward at the separation position, the position of the leading edge of the paper returned to the first guiding position passes at least the position of the intersection point where an imaginary extension line of the upper surface of the switching gate plate intersects with the upper surface of the upper roller.

3. 3. The paper folding device according to claim 1, wherein the inclination angle of the switching gate plate at the first guide position is set to an angle that prevents buckling even when the type of paper guided upward on the switching gate plate is thin paper.

4. A paper folding device as described in claim 1 or claim 2, characterized in that, as a countermeasure against impact noise, even if the type of paper is cardboard, the switching gate plate is switched from the first guiding position to the away position, thereby preventing the leading end of the paper from hitting the upper surface of the upper roller and preventing the generation of impact noise.

5. 3. The paper folding device according to claim 1, wherein after the folding plate has lowered to fold the leading edge of the paper, the control means further controls the first pair of conveying rollers to convey the folded leading edge portion of the paper after the folding of the leading edge of the paper toward the nip portion of the second pair of conveying rollers, and to press and fold the folded leading edge portion of the paper by sandwiching the folded leading edge portion of the paper between the nip portions of the second pair of conveying rollers.

6. A paper folding device as described in claim 1 or claim 2, characterized in that a crease processing section is further provided upstream of the first conveying roller pair in the paper conveying direction, and the crease processing section is configured to form a crease in advance at the fold when folding the flat paper.

7. 3. The paper folding device according to claim 1, wherein the distance between the switching gate plate disposed at the second guide position and the folding plate disposed at the folding position is configured so that at least a gap sufficient to transport the paper is secured between the folding plate and the switching gate plate.

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