Stacker apparatus and method for controlling the same

Abstract

To accurately align and stack corrugated board sheets produced under various order conditions on a support table without damaging or jamming-up the corrugated board sheets.SOLUTION: A stacker apparatus 1 comprises: a conveyor 8 and 1st-7th lap conveyors 11-17 for conveying corrugated board sheets; a support table 26 on which the corrugated board sheets fed from the most downstream 7th lap conveyor 17 are stacked; a stopper 76 which is provided on the support table and against which the front ends of the corrugated board sheets abut; and a control device 100 that performs lifting control for lifting the 7th lap conveyor. The control device performs the lifting control so as to reduce a level difference D between the conveyance surface of the 7th lap conveyor on which the conveyed corrugated board sheets are placed and the upper surface of an uppermost corrugated board sheet S1 on the support table more as the corrugated board sheets produced at a corrugater line are larger in weight.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a stacker device that is provided at the end of a corrugator line and stacks cardboard sheets continuously supplied along this line, and a control method therefor.

Background Art

[0002] Generally, a stacker device has a conveying conveyor arranged on the downstream side of a cutter, a plurality of lap conveyors arranged in series on the downstream side of the conveying conveyor, and a support table arranged on the outlet side of the most downstream lap conveyor. The cardboard sheet cut to a predetermined length by the cutter is conveyed one by one at intervals by the conveying conveyor and then transferred to the most upstream lap conveyor. Each lap conveyor is set to have a slower conveying speed than the conveying conveyor, and the sheets sent one by one from the conveying conveyor are conveyed in an overlapping state (overlap state) like shingles and discharged from the outlet of the most downstream lap conveyor. The sheet discharged from the most downstream lap conveyor abuts against a stopper (hereinafter sometimes referred to as a "front stopper") and is stacked on the support table.

[0003] This type of stacker device is described in, for example, Patent Documents 1 and 2. Patent Document 1 describes a lift control device having a variable speed drive mechanism for raising and lowering a table, a sheet position detection mechanism for detecting the position of the uppermost sheet stacked on the table at at least three positions in the vertical direction, and a control mechanism for controlling the lowering speed of the table according to a sheet position detection signal. Further, Patent Document 2 describes a sheet disturbance prevention device having a pressing roll located above the downstream side of the sheet stacking portion, rotatable in the sheet traveling direction and non-rotatable in the reverse direction, and a control mechanism capable of variably adjusting the pressing force of the pressing roll against the sheet.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

[0005] Here, in order to align and stack cardboard sheets on the support table, it is considered desirable to set the drop (height difference) between the conveying surface of the most downstream wrap conveyor on which the conveyed cardboard sheet is placed (in other words, the lower surface of the cardboard sheet discharged from the most downstream wrap conveyor) and the upper surface of the uppermost cardboard sheet stacked on the support table to an appropriate value. In this regard, the lifting control device described in Patent Document 1 above always keeps the drop of the cardboard sheet optimal and reduces the disturbance of the stacked cardboard sheets. Specifically, this lifting control device uses three photoelectric tubes provided at different heights at the side position of the table to change the lowering speed of the table in three stages according to the stacking amount of the cardboard sheets, so as to maintain the drop of the cardboard sheet substantially constant while stacking on the table.

[0006] However, in the technique described in Patent Document 1, cardboard sheets produced under various order conditions are stacked at the same drop without considering the differences in the conditions of the cardboard sheets to be produced. Therefore, depending on the order conditions, when the cardboard sheet discharged from the conveyor hits the front stopper, the stacking of the sheets may be disturbed by the reaction. Specifically, in the case of a cardboard sheet with a large weight, the kinetic energy (K = 1 / 2mv 2 ) of the sheet at the time of discharge from the conveyor is larger than that of a sheet with a small weight (assuming they are discharged at the same speed). Therefore, it collides with the front stopper more forcefully, and the sheet moves backward and is displaced in the front-rear direction and stacked due to the reaction.

[0007] On the other hand, the sheet disorder prevention device described in Patent Document 2 is configured to prevent such a displacement in the front-rear direction. Specifically, in this sheet disorder prevention device, the corrugated sheet fed onto the table is passed between the uppermost sheet and the pressing roll and brought into contact with the front stopper to stop. More specifically, the running speed of the sheet is reduced and slowed down by the contact resistance between the pressing roll and the uppermost sheet, and the displacement to the rearward side is regulated by the reverse prevention mechanism of the pressing roll, so that the front end side of the sheet is stacked in a state close to the front stopper, preventing the displacement to the rearward side accompanying the collision with the front stopper.

[0008] As described above, in the technique described in Patent Document 2, the sheet discharged from the conveyor is passed through a slight gap between the lower surface of the pressing roll and the upper surface of the uppermost sheet to apply contact resistance to the sheet and decelerate it. However, in reality, the sheet vigorously discharged from the conveyor may not smoothly enter this gap, collide with the pressing roll, damage the sheet, or jam the sheet.

[0009] The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a stacker device and a control method thereof that can accurately align and stack corrugated sheets produced under various order conditions on a support table without causing problems such as damaging or jamming the corrugated sheets.

Means for Solving the Problems

[0010] To achieve the above object, the present invention provides a stacker device provided at the end of a corrugator line for stacking corrugated sheets continuously supplied along this line, comprising: a plurality of conveyors for conveying the corrugated sheets cut by a cutter to the downstream side; a support table for stacking the corrugated sheets discharged from the most downstream conveyor among the plurality of conveyors; a stopper provided on the support table against which the front end of the corrugated sheet discharged from the most downstream conveyor abuts; a lifting mechanism configured to be able to lift and lower the most downstream conveyor and / or the support table; and a control device configured to perform lifting control for lifting and lowering the most downstream conveyor and / or the support table by controlling the lifting mechanism. The control device is configured to perform lifting control such that the greater the weight of the corrugated sheets produced on the corrugator line, the smaller the drop between the conveying surface of the most downstream conveyor on which the conveyed corrugated sheets are placed and the upper surface of the uppermost corrugated sheet on the support table.

[0011] According to the present invention configured as described above, for a heavy cardboard sheet, it is stacked on the support table in a state where the drop is small. As a result, for a heavy cardboard sheet discharged from the most downstream conveyor, when the front end portion of the cardboard sheet that has passed through the outlet of the most downstream conveyor and is no longer supported by anything tilts downward, the sagging portion can be accurately brought into contact with the upper surface of the uppermost cardboard sheet (hereinafter appropriately referred to as the "uppermost sheet") loaded immediately below. This cardboard sheet is fed out from the most downstream conveyor while receiving a frictional force in the direction opposite to the traveling direction generated on the contact surface with the uppermost sheet, and slides on the upper surface of the uppermost sheet and advances. As a result, for a heavy cardboard sheet, before reaching the stopper, it decelerates due to the frictional force and its kinetic energy decreases, so that it does not collide forcefully when reaching the stopper, and it is possible to suppress the backward displacement due to the reaction of the collision. Further, according to the present invention, since a special mechanism (such as a pressing roll described in Patent Document 2) for decelerating the cardboard sheet is not used, the device configuration can be simplified, and problems such as damaging the cardboard sheet or jamming it can be suppressed. On the other hand, according to the present invention, for a light cardboard sheet, it is stacked on the support table in a state where the drop is large. As a result, for a light cardboard sheet, the period (distance) of contacting the uppermost sheet and receiving frictional force can be shortened, or the cardboard sheet can be fed out without contacting the uppermost sheet and without receiving frictional force. As a result, a light cardboard sheet can be surely made to reach the stopper. From the above, according to the present invention, by setting an appropriate drop according to the production conditions of the cardboard sheet and adjusting the period (distance) during which the cardboard sheet discharged from the most downstream conveyor receives frictional force from the uppermost sheet on the support table, cardboard sheets produced under various order conditions can be accurately aligned and stacked on the support table.

[0012] In the present invention, preferably, the control device is configured to perform lifting control so as to maintain the drop at a target value corresponding to the weight of the cardboard sheet produced on the corrugator line, and the target value is set to a smaller value as the weight of the cardboard sheet is larger. According to the present invention configured as described above, during the production of the cardboard sheet, the drop can be accurately maintained at a target value suitable for the weight of the cardboard sheet by the lifting control of the most downstream conveyor and / or the support table.

[0013] In the present invention, preferably, the target value is set according to the flute of the cardboard sheet produced on the corrugator line. In the present invention configured as described above, assuming that the weight of the cardboard sheet corresponds to the flute of the cardboard sheet, the target value of the drop is set according to this flute. Thereby, compared with the case where the target value is set by directly judging the weight of the cardboard sheet to be produced, the control configuration can be simplified.

[0014] In the present invention, preferably, the target value is set according to the dimensions of the cardboard sheet produced on the corrugator line. In the present invention configured as described above, assuming that the weight of the cardboard sheet corresponds to the dimensions of the cardboard sheet, the target value of the drop is set according to this dimension. Thereby, compared with the case where the target value is set by directly judging the weight of the cardboard sheet to be produced, the control configuration can be simplified.

[0015] In the present invention, preferably, the target value is set to a larger value as the length along the conveyance direction of the cardboard sheet produced on the corrugator line is longer. According to the present invention configured as described above, for a cardboard sheet having a long length (conveyance direction length) along the conveyance direction, by setting a large drop, this cardboard sheet can be surely made to reach the stopper.

[0016] In the present invention, preferably, when the drop is greater than the target value, the control device is configured to perform lifting control to decelerate the rising speed of the most downstream conveyor and / or the lowering speed of the support table so as to return the drop to the target value. According to the present invention configured as described above, when the drop becomes greater than the target value, the drop can be returned to the target value so that the target value can be accurately maintained.

[0017] In the present invention, preferably, when the drop is smaller than the target value, the control device is configured to perform lifting control to accelerate the rising speed of the most downstream conveyor and / or the lowering speed of the support table so as to return the drop to the target value. According to the present invention configured as described above, when the drop becomes smaller than the target value, the drop can be returned to the target value so that the target value can be accurately maintained.

[0018] In the present invention, preferably, it further includes a sheet detection sensor for detecting the height level of the corrugated sheet stacked on the support table, and the control device determines whether the drop is greater than the target value based on the detection result of the sheet detection sensor, and after a predetermined time has elapsed since it is determined that the drop is greater than the target value, it is configured to start lifting control to decelerate the rising speed of the most downstream conveyor and / or the lowering speed of the support table. In the present invention configured as described above, when it is determined that the drop is greater than the target value, the deceleration of the rising speed of the most downstream conveyor is not started immediately, but after a certain period of time has elapsed since this determination, the deceleration of the rising speed of the most downstream conveyor is started. Thereby, it is possible to prevent the misdetection of the sheet detection sensor from adversely affecting the stacking of the corrugated sheet.

[0019] In the present invention, preferably, it further has a sheet detection sensor for detecting the height level of the corrugated sheet stacked on the support table. The control device determines whether the drop is smaller than the target value based on the detection result of the sheet detection sensor, and after a predetermined time has elapsed since it is determined that the drop is smaller than the target value, it is configured to start lifting and lowering control for accelerating the rising speed of the most downstream conveyor and / or the lowering speed of the support table. In the present invention configured as described above, when it is determined that the drop is smaller than the target value, the acceleration of the rising speed of the most downstream conveyor is not started immediately, but the acceleration of the rising speed of the most downstream conveyor is started after a certain period of time has elapsed since this determination. Thereby, it is possible to prevent the misdetection of the sheet detection sensor from adversely affecting the stacking of the corrugated sheets.

[0020] In a preferred example of the present invention, the stacker device starts the production of corrugated sheets on the corrugator line in a state where the drop is larger than the target value, and further has a sheet detection sensor for detecting the height level of the corrugated sheets stacked on the support table. The sheet detection sensor is provided at a position capable of detecting the height level corresponding to the target value or a height level lower than the height level. The control device determines whether the drop has reached the target value based on the detection result of the sheet detection sensor when the production of corrugated sheets starts on the corrugator line and the corrugated sheets start to be stacked on the support table, and continues to stop the lifting and lowering of the most downstream conveyor and the support table until it is determined that the drop has reached the target value. When it is determined that the drop has reached the target value, the lifting and lowering control of the most downstream conveyor and / or the support table is performed so as to maintain the drop at the target value.

[0021] From another perspective, to achieve the above object, the present invention provides a control method for a stacker device that is provided at the end of a corrugator line and stacks cardboard sheets continuously supplied along this line. The stacker device includes: a plurality of conveyors that convey the cardboard sheets cut by a cutter to the downstream side; a support table that stacks the cardboard sheets discharged from the most downstream conveyor among the plurality of conveyors; a stopper provided on the support table, against which the front end of the cardboard sheet discharged from the most downstream conveyor abuts; a lifting mechanism configured to be able to raise and lower the most downstream conveyor and / or the support table; and a control device configured to perform lifting control to raise and lower the most downstream conveyor and / or the support table by controlling the lifting mechanism. The control method for the stacker device includes a step of performing lifting control by the control device such that the greater the weight of the cardboard sheet produced on the corrugator line, the smaller the drop between the conveying surface of the most downstream conveyor on which the conveyed cardboard sheet is placed and the upper surface of the uppermost cardboard sheet on the support table.

Advantages of the Invention

[0022] According to the stacker device and its control method of the present invention, cardboard sheets produced under various order conditions can be accurately aligned and stacked on the support table without causing problems such as damaging or jamming the cardboard sheets.

Brief Description of the Drawings

[0023]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Mode for Carrying Out the Invention

[0024] Hereinafter, with reference to the drawings, a stacker device and its control method according to the embodiment of the present invention will be described.

[0025] In this embodiment, as a stacker device, an up-stacker device in which a wrap conveyor rises with respect to a support table is taken as an example. However, the present invention is also applicable to a down-stacker device in which another type of support table descends with respect to the wrap conveyor, or an up-down stacker device having both mechanisms of an up-stacker device and a down-stacker device.

[0026] <Configuration of Stacker Device> First, with reference to FIGS. 1 and 2, the basic configuration of the stacker device according to the embodiment of the present invention will be described. FIG. 1 is a schematic front view showing a part of a corrugator line including the stacker device according to the present embodiment, and FIG. 2 is a schematic front view showing an enlarged part of the stacker device shown in FIG. 1.

[0027] As shown in FIGS. 1 and 2, a cutter 2 for cutting a cardboard sheet (double-sided cardboard sheet) continuously supplied from a corrugator line (not shown) to a predetermined length is provided upstream of the stacker device 1 according to this embodiment. A cutter inlet conveyor 4 is provided upstream (sheet inlet side) of the cutter 2, and a cutter outlet conveyor 6 is provided downstream (sheet outlet side) of the cutter 2.

[0028] In the stacker device 1, a conveying conveyor 8 is provided downstream of the above-described cutter outlet conveyor 6, and a plurality of wrap conveyors are provided downstream of the conveying conveyor 8. These plurality of wrap conveyors include, in order from the upstream side, a NO1 wrap conveyor 11, a NO2 wrap conveyor 12, a NO3 wrap conveyor 13, a NO4 wrap conveyor 14, a NO5 wrap conveyor 15, a NO6 wrap conveyor 16, and a NO7 wrap conveyor (the most downstream conveyor) 17. Note that as the plurality of wrap conveyors, more wrap conveyors such as a NO8 wrap conveyor and a NO9 wrap conveyor may be provided. The conveying conveyor 8 and the NO1 to NO7 wrap conveyors 11 to 17 correspond to an example of the "plurality of conveyors" in the present invention.

[0029] Here, the NO1 to NO7 wrap conveyors 11 to 17 are belt conveyors, and as will be described later, each is provided with an individual drive motor and can be operated at different speeds. Also, the speeds of the respective wrap conveyors 11 to 17 are set to be always slower than the speed of the conveying conveyor 8. Further, the height of the upstream end of the most upstream NO1 wrap conveyor 11 is set to be lower than the downstream end of the conveying conveyor 8.

[0030] Due to such speed differences and height differences between the conveyors, the corrugated sheet conveyed from the conveying conveyor 8 partially overlaps on the corrugated sheet before it is placed on the NO1 lap conveyor 11, and the corrugated sheets are in an overlapping state. Then, the corrugated sheet transferred to the NO1 lap conveyor 11 is conveyed downstream while remaining in the overlapping state, transfers between the NO2 to NO7 lap conveyors 12 to 17, and is discharged from the downstream end of the most downstream NO7 lap conveyor 17.

[0031] A frame 24 is provided on the outlet side of the most downstream NO7 lap conveyor 17. At a lower position within this frame 24, a support table 26 for supporting the sheet laminate and a pallet 28 on which the corrugated sheet is placed and supplied are provided. Note that the corrugated sheet may be directly stacked on the support table 26 without using the pallet 28.

[0032] Also, an elevating frame 30 is provided at an upper position within the frame 24. A part of the elevating frame 30 and the NO7 lap conveyor 17 are connected to each other by a connecting member 32, and the elevating frame 30 and the NO7 lap conveyor 17 can be integrally elevated and lowered. In this way, in the stacker device 1, the height level of the support table 26 is fixed, and the NO7 lap conveyor 17 can be elevated and lowered.

[0033] Next, as shown in FIGS. 1 and 2, an elevating frame lifting motor 128 is provided on the upper part of the frame 24. A chain 38 is connected to a sprocket 36 attached to the drive shaft of this motor 128. One end of this chain 38 is connected to the downstream end of the elevating frame 30, and a counterweight 40 is coupled to the other end of the chain 38, enabling the elevating frame 30 to be easily driven to elevate and lower.

[0034] Furthermore, a plurality of frames 42, 44, 46, 48 are provided in order from the upstream. Among these frames, frames 42, 44, 46 are for supporting the NO4 lap conveyor 14, NO5 lap conveyor 15, and NO6 lap conveyor 16 so that they can move up and down. Also, frames 46, 48 are for supporting the NO7 lap conveyor 17 and the elevating frame 30 so that they can move up and down together with the frame 24.

[0035] Also, as shown in FIG. 1, an NO4 - NO6 lap conveyor elevating motor 129 is provided at the upper part of the frame 42. An endless chain 54 is connected to a sprocket 52 attached to the drive shaft of this motor 129. A lap conveyor slide member 56 connected to the NO4 lap conveyor 14 and the NO5 lap conveyor 15 is connected to a part of this chain 54. Thus, the NO4, NO5, and NO6 lap conveyors 14, 15, 16 can move up and down so that the inclination angle changes.

[0036] In this way, both the elevating frame elevating motor 128 and the NO4 - NO6 lap conveyor elevating motor 129 enable the elevating frame 30 and the NO4 - NO7 lap conveyors 14, 15, 16, 17 to move up and down. Note that the elevating frame 30, the elevating frame elevating motor 128, etc. correspond to an example of the "elevating mechanism" in the present invention.

[0037] Next, as shown in FIG. 2, the NO7 lap conveyor 17 includes a telescopic frame 58. Inside this frame 58, a belt 60 constituting the NO7 lap conveyor 17 and five rolls 61, 62, 63, 64, 65 are attached in order from the downstream side. Among these rolls, the rolls 62, 64, 65 are fixedly arranged, and the rolls 61, 63 are movable in the conveying direction. Also, an NO7 lap conveyor moving motor 130 is provided at the upstream side part of the elevating frame 30. On the other hand, an NO7 lap conveyor driving motor 121 is provided at the upstream side part of the frame 58 of the NO7 lap conveyor 17.

[0038] The drive shaft of the motor 130 for moving the NO7 wrap conveyor is connected to the roll 63 via a telescopic frame 58. When this motor 130 is driven, the frame 58 moves forward and backward in the conveying direction and the roll 63 moves in the conveying direction. At the same time, when the roll 63 moves, the roll 61 located at the front end (downstream end) of the NO7 wrap conveyor 17 also moves in the conveying direction. In FIG. 2, the state where the NO7 wrap conveyor 17 shown by the solid line extends to the downstream side and is located at the most downstream side is shown, and the state where the NO7 wrap conveyor 17 shown by the chain line retreats to the upstream side and is located at the most upstream side is shown.

[0039] As shown in FIG. 2, a stopper 76 is attached to the downstream side portion of the lifting frame 30 via a slide member 78. Further, a motor 131 for moving the stopper is attached to this slide member 78, and a pinion 82 is attached to the drive shaft of this motor 131. Furthermore, a rack 84 is provided in the region of the downstream half of the lifting frame 30. When the motor 131 is driven by these rack 84 and pinion 82, the stopper 76 can move in the region between the central position and the downstream end of the lifting frame 30.

[0040] Also, as shown in FIG. 2, a lower-level sheet detection sensor 88 and an upper-level sheet detection sensor 89 provided at different height positions (hereinafter simply referred to as "sheet detection sensors 88, 89" when not distinguishing between them) are fixed to the stopper 76. These sheet detection sensors 88, 89 detect the height level of the upper surface of the uppermost corrugated sheet (uppermost sheet) loaded on the support table 26, specifically on the pallet 28. Specifically, each of the sheet detection sensors 88, 89 includes a light projecting unit and a light receiving unit (not shown), and detects the presence or absence of a sheet at the height of the optical axis based on whether the light projected from the light projecting unit is detected by the light receiving unit. More specifically, the light projecting unit and the light receiving unit are mounted so as to be separated outward in the width direction from the loading position of the corrugated sheet on the pallet 28, and when the light projected horizontally from the light projecting unit is blocked by the loaded sheet and not detected by the light receiving unit, a sheet detection signal is sent to a control device 100 described later.

[0041] Here, the NO7 lap conveyor 17, which is the most downstream lap conveyor, is connected to the lifting frame 30 by a connecting member 32. Also, the stopper 76 is attached to the same lifting frame 30 via a slide member 78. Since the above-described sheet detection sensors 88, 89 are fixed to the stopper 76, both the NO7 lap conveyor 17 and the sheet detection sensors 88, 89 will move up and down integrally with the lifting frame 30. Therefore, the height difference between the conveying surface of the NO7 lap conveyor 17 (which means the upper surface of the belt 60 of the NO7 lap conveyor 17 on which the conveyed corrugated sheet is placed; the same shall apply hereinafter) and the optical axes of the sheet detection sensors 88, 89 will always be kept constant during the production of the corrugated sheet.

[0042] On the other hand, in the stacker device 1 according to the present embodiment, since the support table 26 does not move up and down, when the NO7 wrap conveyor 17 moves up and down, the difference (height difference) between the conveyance surface of the NO7 wrap conveyor 17 and the upper surface of the pallet 28 on the support table 26 changes. Therefore, when the loading amount of the cardboard sheets on the pallet 28 is the same, the higher the NO7 wrap conveyor 17 rises, the greater the difference between the conveyance surface of the NO7 wrap conveyor 17 and the height level of the uppermost sheet loaded on the pallet 28 (hereinafter appropriately referred to as the "upper surface level"). On the contrary, when the height of the NO7 wrap conveyor 17 is the same, the greater the loading amount of the cardboard sheets on the pallet 28, the smaller this difference becomes. Therefore, in the present embodiment, during the production of cardboard sheets, in order to set such a difference to an appropriate value and stack the cardboard sheets in alignment, the upward movement of the NO7 wrap conveyor 17 is controlled according to the loading state of the cardboard sheets on the pallet 28.

[0043] In addition, there is a range within which stable stacking is possible for the difference between the conveyance surface of the NO7 wrap conveyor 17 and the upper surface level of the uppermost sheet on the pallet 28. For example, if the difference is too large, the falling distance of the cardboard sheet discharged from the NO7 wrap conveyor 17 is long, so the posture of the cardboard sheet may tilt during the fall, and it may not be accurately stacked on the previously loaded cardboard sheet. On the contrary, if the difference is too small, the front end of the cardboard sheet discharged from the NO7 wrap conveyor 17 may collide with the side surface of the previously loaded cardboard sheet.

[0044] Therefore, in this embodiment, two sheet detection sensors 88 and 89 are used. One sheet detection sensor (lower level sheet detection sensor) 88 is arranged such that the height of its optical axis coincides with the lower limit height of the upper surface level of the uppermost sheet corresponding to the maximum drop height at which stacking is possible. The other sheet detection sensor (upper level sheet detection sensor) 89 is arranged such that the height of its optical axis coincides with the upper limit height of the upper surface level of the uppermost sheet corresponding to the minimum drop height at which stacking is possible. The optical axis height of the lower level sheet detection sensor 88 is defined as "lower level", and the optical axis height of the upper level sheet detection sensor 89 is defined as "upper level".

[0045] In this embodiment, during the production of the cardboard sheet, the ascending operation of the NO7 wrap conveyor 17 is controlled so that the upper surface level of the uppermost sheet is adjusted within the height range between such lower level and upper level. In particular, the NO7 wrap conveyor 17 is controlled so that the upper surface level of the uppermost sheet is set to a "target level" according to the conditions of the cardboard sheet to be produced, enabling the cardboard sheets to be stacked at an appropriate drop height.

[0046] <Electrical Configuration of the Stacker Device> Next, with reference to FIG. 3, the electrical configuration of the stacker device according to this embodiment will be described. As shown in FIG. 3, the control device 100 of the stacker device 1 is provided with a central control unit 110 including an I / O port 102, a CPU 104, a ROM 106, a RAM 108, etc. connected to this I / O port 102.

[0047] The ROM 106 stores a control program for controlling the entire stacker device 1, and the RAM 108 functions as its work area.

[0048] The upper production management device 112 is connected to the I / O port 102. This upper production management device 112 manages and controls the production of the entire production line of the cardboard sheet. For example, the number of sheets to be produced, the sheet cutting length (corresponding to the length in the conveyance direction of the cardboard sheet after cutting by the cutter 2), the flute, the basis weight of each base paper used (1m2 It stores production order data such as the weight per unit area), etc., and transmits the data of a plurality of orders to be produced at the start of production in a day.

[0049] Also, rotation pulse signals are input to the I / O port 102 from pulse generators (PGs) installed in the double facer drive motor 114 and the cutter outlet conveyor drive motor 116, respectively. Further, the above-described lower level sheet detection sensor 88 and upper level sheet detection sensor 89 are connected to the I / O port 102.

[0050] A CPU for motor driver 120 is connected to the CPU 104, and drive motors 121 - 127 for the NO1 - NO7 lap conveyors 11 - 17, a lift frame lifting motor 128, and a NO4 - NO6 lap conveyor lifting motor 129 are connected to the CPU for motor driver 120 via motor drivers 134 - 142, respectively.

[0051] Commands (startup, speed, etc.) to each of the motors 121 - 129 are transmitted from the CPU 104 in the order of the CPU for motor driver 120 and each of the motor drivers 134 - 142, and information (such as rotation pulse signals) of each of the motors 121 - 129 is input from each of the motor drivers 134 - 142 in the order of the CPU for motor driver 120 and the CPU 104.

[0052] Next, the control program stored in the ROM 106 will be described. The control program stored in the ROM 106 includes a "conveyor drive control program", a "rear-end distance calculation program", and a "lifting control program". The conveyor drive control program is a program for controlling the drive motors 121 to 127 of the NO1 to NO7 wrap conveyors 11 to 17 during production to convey the sheet. The rear-end distance calculation program is a program for inputting and updating the data of each memory during production to calculate the rear-end distance of the sheet discharged from the NO7 wrap conveyor 17 (the entire disclosure of Japanese Patent Application No. 2023-003222 is hereby incorporated by reference into this specification). The lifting control program is a program for controlling the lifting motor 128 of the lifting frame during production to keep the difference between the lower surface of the sheet discharged from the downstream end of the NO7 wrap conveyor 17 and the upper surface of the sheet stacked on the pallet 28 at an appropriate value. In the present embodiment, the details of the lifting control method executed according to this lifting control program will be described later.

[0053] <Lifting Control Method> Next, in the present embodiment, the lifting control method executed by the control device 100 according to the lifting control program will be described.

[0054] Basic concept of lifting control First, with reference to FIGS. 4 and 5, the basic concept of the lifting control according to the present embodiment will be described. FIGS. 4 and 5 show schematic front views of a part of the stacker device 1, specifically, the NO7 wrap conveyor 17, the support table 26, the pallet 28, and the stopper 76. As shown in FIG. 4, in the present embodiment, during the production of the corrugated sheet, the control device 100 adjusts the height difference D between the conveyance surface of the NO7 wrap conveyor 17 (the upper surface of the belt 60 of the NO7 wrap conveyor 17, or in other words, the lower surface of the corrugated sheet S2 conveyed by the NO7 wrap conveyor 17) and the upper surface of the uppermost sheet S1 stacked on the pallet 28 on the support table 26 to an appropriate value. Specifically, the control device 100 controls the lifting of the NO7 wrap conveyor 17 via the motor driver 141 and the lifting frame lifting motor 128 (FIG. 3).

[0055] Specifically, in the present embodiment, the control device 100 controls the lifting of the NO7 wrap conveyor 17 such that the greater the weight of the corrugated sheet produced on the corrugator line, the smaller the height difference D (see FIG. 5(A)), or in other words, the smaller the weight of the corrugated sheet produced on the corrugator line, the greater the height difference D (see FIG. 5(B)). In this case, the control device 100 performs lifting control so as to maintain the height difference D at a "target value" corresponding to the weight of the corrugated sheet produced on the corrugator line. By doing so, the corrugated sheets produced under various order conditions can be accurately aligned and stacked on the support table without damaging or jamming the corrugated sheets.

[0056] Next, the lifting control according to the present embodiment will be specifically described. In the present embodiment, during the production of the corrugated sheet, the control device 100 sequentially performs the following operations (i) to (iii) according to the lifting control program.

[0057] Operation (i) The control device 100 starts production from a state where no corrugated sheet is loaded on the pallet 28. When the corrugated sheet is not detected by the lower-level sheet detection sensor 88 during the stage where the corrugated sheet is discharged from the NO7 wrapping conveyor 17 and loaded onto the pallet 28, the NO7 wrapping conveyor 17 is stopped at the lower loading start position. When the amount of corrugated sheets loaded on the pallet 28 is small, such as at the start of production for a day or immediately after replacing the pallet 28, and the upper surface level of the uppermost sheet S1 has not reached the lower level, since the drop D is too large, the control device 100 stops the NO7 wrapping conveyor 17 at the lower loading start position without raising it. While the rise of the NO7 wrapping conveyor 17 is thus stopped, the corrugated sheets are sequentially discharged by the driving of the NO1 to NO7 wrapping conveyors 11 to 17, and the amount of corrugated sheets loaded on the pallet 28 gradually increases. Therefore, the upper surface level of the uppermost sheet S1 gradually rises, and the drop D becomes smaller.

[0058] Operation (ii) After the above operation (i), the corrugated sheets are sequentially loaded. When the corrugated sheet is detected by the lower-level sheet detection sensor 88, thereafter, when the upper surface level of the uppermost sheet S1 reaches the "target level" according to the conditions of the corrugated sheet to be produced, the control device 100 starts to raise the NO7 wrapping conveyor 17. This target level is between the lower level detected by the lower-level sheet detection sensor 88 and the upper level detected by the upper-level sheet detection sensor 89, and is a height level corresponding to the target value of the above-described drop D, that is, a height level set according to the weight of the corrugated sheet to be produced. When the corrugated sheet is detected by the lower-level sheet detection sensor 88, the control device 100 reads out the "rise start waiting time" set according to such a target level and starts counting. When this counting is completed, the control device 100 starts to raise the NO7 wrapping conveyor 17. The details of the target level and the rise start waiting time will be described later.

[0059] Operation (iii) After the above operation (ii), while the cardboard sheets are being sequentially loaded, the control device 100 performs lifting control to raise the NO7 wrapping conveyor 17 so as to maintain the drop D at the start of the ascent of the NO7 wrapping conveyor 17 in (ii). Specifically, at the start of the ascent of the NO7 wrapping conveyor 17 in (ii), since the upper surface level of the uppermost sheet S1 has reached the target level (that is, the drop D is set to the target value), the control device 100 thereafter maintains the upper surface level at the target level. In other words, the control device 100 performs lifting control to raise the NO7 wrapping conveyor 17 in accordance with the absolute rise of the upper surface level with respect to the upper surface of the pallet 28 so that the relative height relationship between the upper surface level and the target level does not change.

[0060] Regarding "target level" Next, the target level (corresponding to the target value of the drop D) applied to the upper surface level of the uppermost sheet S1 in the lifting control according to the present embodiment will be specifically described. As described above, in the present embodiment, the control device 100 sets the target level according to the weight of the cardboard sheet to be produced. Therefore, first, the weight of this cardboard sheet will be described.

[0061] The weight (g) of the cardboard sheet is obtained by " 2 the area of the cardboard sheet (m 2 ) × basis weight (g / m

[0062] Therefore, in this embodiment, from the perspective of simplifying control, without considering the area of the cardboard sheet, a cardboard sheet with a large basis weight is regarded as a cardboard sheet with a large weight, and its weight is determined according to the flute of the cardboard sheet. Specifically, a sheet with AB flute is regarded as a heavy sheet, a sheet with B flute is regarded as a light sheet, and a sheet with A flute is regarded as a sheet with a weight between these AB flute and B flute. And in this embodiment, the control device 100 sets the target level (corresponding to the target value of the drop D) used for the above lifting control according to the flute of the cardboard sheet to be produced.

[0063] FIG. 6 shows an example of the target level set according to the flute of the cardboard sheet in this embodiment. As shown in FIG. 6, in this embodiment, for a relatively heavy cardboard sheet with AB flute, the control device 100 sets the target level at a high position, for a relatively light cardboard sheet with B flute, the control device 100 sets the target level at a low position, and for a cardboard sheet with A flute having an intermediate weight, the control device 100 sets the target level at a position between the target levels of AB flute and B flute respectively. In the following, in addition to the target level set for each flute, an example of the lower level detected by the lower level sheet detection sensor 88 and the upper level detected by the upper level sheet detection sensor 89 is shown. (Numerical examples of each level) ·Height difference between the conveying surface and the upper level: about 20 mm ·Height difference between the conveying surface and the target level of AB flute: about 30 mm ·Height difference between the conveying surface and the target level of A flute: about 40 mm ·Height difference between the conveying surface and the target level of B flute: about 50 mm ·Height difference between the conveying surface and the lower level: about 60 mm

[0064] Regarding "waiting time for start of ascent" Next, the rising start waiting time used in the above operation (ii) will be specifically described. This rising start waiting time corresponds to the time counted from when the corrugated sheet is detected by the lower level sheet detection sensor 88 until the NO7 wrap conveyor 17 starts to rise at the stage of operation (ii). In the present embodiment, since a sensor capable of directly detecting that the upper surface level of the uppermost sheet S1 has reached the target level is not used, the control device 100 defines the rising start waiting time corresponding to the target level, and determines that the upper surface level of the uppermost sheet S1 has reached the target level when the counting of this rising start waiting time is completed.

[0065] Referring to FIG. 7, the rising start waiting time will be described in detail. In each of the left and right diagrams of FIG. 7, the positions of the upper surface levels of the uppermost sheet S1 at the start and completion of the counting of the rising start waiting time are shown. Here, the relative height relationship between the upper surface level of the uppermost sheet S1 with respect to the target level that moves up and down together with the NO7 wrap conveyor 17 and the absolute height relationship between the upper surface level of the uppermost sheet S1 with respect to the upper surface of the pallet 28 that does not move up and down are considered separately. Then, in order for the upper surface level of the uppermost sheet S1 to exactly reach the target level when the counting of the rising start waiting time is completed, the relative rising amount of the upper surface level during the rising start waiting time needs to match the height difference between the lower level and the target level (see the right diagram of FIG. 7).

[0066] Such a relative rising amount of the upper surface level during the rising start waiting time is represented by Equation (1) because at the stage of operation (ii), the NO7 wrap conveyor 17 stops downward and the target level does not rise. Relative rising amount of the upper surface level during the rising start waiting time (mm) = Absolute rising amount of the upper surface level during the rising start waiting time (mm) = Increase in the amount of sheets loaded during the rising start waiting time (mm) Equation (1)

[0067] And the increase in the amount of sheets loaded during the rising start waiting time in Equation (1) is represented by Equation (2). Increase in the amount of sheet loaded during the waiting time for start of ascent (mm) = Increase in the amount of sheet loaded per unit time (mm / second) × Waiting time for start of ascent (seconds) = Sheet loading acceleration (mm / second) × Waiting time for start of ascent (seconds) Formula (2)

[0068] And the sheet loading acceleration in Formula (2) is represented by Formula (3). Sheet loading acceleration (mm / second) = Number of sheets discharged from the NO7 wrap conveyor per unit time (sheets / second) × Sheet thickness (mm / sheet) Formula (3)

[0069] And considering the number of sheets discharged per unit time in Formula (3), for the corrugated sheet conveyed on the NO7 wrap conveyor 17, when the NO7 wrap conveyor 17 moves by the distance between the rear ends of the corrugated sheets before and after overlapping, one sheet is discharged from the NO7 wrap conveyor 17. Therefore, the number of sheets discharged per unit time in Formula (3) is represented by Formula (4). Number of sheets discharged from the NO7 wrap conveyor per unit time (sheets / second) = Moving distance of the NO7 wrap conveyor per unit time (mm / second) ÷ Distance between the rear ends of the corrugated sheets on the NO7 wrap conveyor (mm / sheet) = Conveying speed of the NO7 wrap conveyor (mm / second) ÷ Distance between the rear ends of the corrugated sheets on the NO7 wrap conveyor (mm / sheet) Formula (4)

[0070] Therefore, from Formulas (3) and (4), the sheet loading acceleration is represented by Formula (5). Sheet loading acceleration (mm / second) = Conveying speed of the NO7 wrap conveyor (mm / second) ÷ Distance between the rear ends of the corrugated sheets on the NO7 wrap conveyor (mm) × Sheet thickness (mm / sheet) Formula (5)

[0071] As shown in formula (5), the sheet loading acceleration will vary depending on the conveyance speed of the NO7 wrap conveyor 17 and the distance between the rear ends of the corrugated sheets on the NO7 wrap conveyor. Therefore, in this embodiment, even if the sheet loading acceleration varies depending on the production conditions, the relative increase in the upper surface level during the waiting time for the start of ascent will be the same, and furthermore, the waiting time for the start of ascent is set so that the amount of increase matches the height difference between the lower level and the target level. Specifically, the greater the conveyance speed of the NO7 wrap conveyor 17, the greater the sheet loading acceleration, so the waiting time for the start of ascent is set shorter accordingly. Also, the shorter the cutting length of the corrugated sheet, the shorter the distance between the rear ends, and the greater the sheet loading acceleration, so the waiting time for the start of ascent is set shorter accordingly.

[0072] Incidentally, the reason why the distance between the rear ends becomes shorter as the cutting length of the corrugated sheet becomes shorter is as follows. The NO1 to NO7 wrap conveyors 11 to 17 are basically set to the same conveyance speed, and there is no speed difference between the conveyors. Therefore, the distance between the rear ends of the corrugated sheet on the NO1 wrap conveyor 11 does not change during the transfer between the subsequent conveyors and is kept constant until the NO7 wrap conveyor 17. And the distance between the rear ends of the corrugated sheet on this NO1 wrap conveyor 11 is obtained by the distance that the previous corrugated sheet is conveyed on the NO1 wrap conveyor 11 during the time from when the previous corrugated sheet rides from the conveyance conveyor 8 onto the NO1 wrap conveyor 11 until the subsequent corrugated sheet rides from the conveyance conveyor 8 onto the NO1 wrap conveyor 11. Therefore, the shorter the cutting length (length in the conveyance direction) of the corrugated sheet, the shorter this time, and accordingly, the distance between the rear ends also becomes shorter.

[0073] FIG. 8 shows an example of the waiting time (ms) for the start of ascent used in this embodiment. Specifically, FIG. 8 shows an example of a table that defines the waiting time for the start of ascent to be applied according to the flute of the corrugated sheet, the cutting length of the corrugated sheet, and the conveyance speed of the NO7 lap conveyor 17. As shown in FIG. 8, it can be seen that the greater the conveyance speed, the shorter the waiting time for the start of ascent, and the shorter the cutting length, the shorter the waiting time for the start of ascent. Also, in the case of AB flute, it can be seen that, compared with B flute under the same conditions, the waiting time for the start of ascent is shorter. This is because, as the thickness of the sheet is greater in AB flute than in B flute, as shown in Equation (5), the sheet stacking acceleration increases, and the upper surface level rapidly rises during a short waiting time for the start of ascent to reach a higher target level.

[0074] A table of the waiting time for the start of ascent as shown in FIG. 8 is obtained in advance by experiments, simulations, etc., and stored in the ROM 106 in the control device 100. Then, when performing the lifting control according to this embodiment, the control device 100 refers to the table stored in the ROM 106 in this way, reads out the waiting time for the start of ascent corresponding to the flute, cutting length, and conveyance speed included in the order conditions to be applied, and performs the lifting control using this waiting time for the start of ascent.

[0075] Regarding "basic ascent speed" Next, the basic ascent speed (basic ascent speed) of the NO7 lap conveyor 17, which is set after the counting of the waiting time for the start of ascent is completed (that is, when performing operation (iii)), will be described. At this time, the control device 100 performs the lifting control so that the ascent speed of the NO7 lap conveyor 17 matches the absolute ascent speed of the upper surface level of the uppermost sheet S1, that is, the sheet stacking acceleration. Therefore, the basic ascent speed of the NO7 lap conveyor 17 is represented by the following Equation (6) from the above Equation (5). Basic ascent speed of NO7 lap conveyor (mm / second) = Sheet stacking acceleration (mm / second) =Conveyor speed of NO7 wrapping conveyor (mm / second) ÷ Distance between the rear ends of corrugated sheets on the NO7 wrapping conveyor (mm) × Sheet thickness (mm / sheet), Equation (6)

[0076] In operation (iii), the control device 100 substitutes the distance between the rear ends calculated by the rear-end distance calculation program, the conveying speed of the NO7 wrapping conveyor 17, and the sheet thickness corresponding to the flute of the corrugated sheet to be produced into the above Equation (6) to obtain the basic rising speed of the NO7 wrapping conveyor 17, and performs lifting control of the NO7 wrapping conveyor 17 using this basic rising speed.

[0077] Regarding correction of basic ascent speed Next, the correction of the basic rising speed of the above-described NO7 wrapping conveyor 17 performed in operation (iii) will be described. In the present embodiment, when the upper surface level of the uppermost sheet S1 falls below the target level due to some irregularity in operation (iii) (in other words, when the drop D becomes larger than the target value), the control device 100 performs lifting control to decelerate the rising speed of the NO7 wrapping conveyor 17 so as to return the upper surface level to the target level. Similarly, when the upper surface level of the uppermost sheet S1 exceeds the target level (in other words, when the drop D becomes smaller than the target value), the control device 100 performs lifting control to accelerate the rising speed of the NO7 wrapping conveyor 17 so as to return the upper surface level to the target level.

[0078] Specifically, when the upper surface level of the uppermost sheet S1 is outside the range between the lower level detected by the lower level sheet detection sensor 88 and the upper level detected by the upper level sheet detection sensor 89, the control device 100 corrects the basic ascending speed of the NO7 wrapping conveyor 17 in order to return the upper surface level within this range. More specifically, when the upper surface level of the uppermost sheet S1 relatively descends with respect to the NO7 wrapping conveyor 17 or the like and the corrugated sheet is not detected by the lower level sheet detection sensor 88, the control device 100 reads out the "deceleration start delay time" according to the production conditions and starts counting. When this count is completed, the ascending speed of the NO7 wrapping conveyor 17 is decelerated so that the upper surface level relatively rises. In this case, the control device 100 applies an ascending speed (hereinafter appropriately referred to as the "corrected ascending speed") obtained by multiplying the basic ascending speed by a predetermined correction factor (<1). Then, when the corrugated sheet is detected by the lower level sheet detection sensor 88, the control device 100 reads out the "deceleration end delay time" according to the production conditions and starts counting. When this count is completed, the deceleration of the ascending speed of the NO7 wrapping conveyor 17 is terminated and the speed returns to the basic ascending speed.

[0079] Similarly, when the upper surface level of the uppermost sheet S1 relatively rises with respect to the NO7 wrapping conveyor 17 or the like and the corrugated sheet is detected by the upper level sheet detection sensor 89, the control device 100 reads out the "acceleration start delay time" according to the production conditions and starts counting. When this count is completed, the ascending speed of the NO7 wrapping conveyor 17 is accelerated so that the upper surface level relatively descends. In this case, the control device 100 applies a corrected ascending speed obtained by multiplying the basic ascending speed by a predetermined correction factor (>1). Then, when the corrugated sheet is not detected by the upper level sheet detection sensor 89, the control device 100 reads out the "acceleration end delay time" according to the production conditions and starts counting. When this count is completed, the acceleration of the ascending speed of the NO7 wrapping conveyor 17 is terminated and the speed returns to the basic ascending speed.

[0080] Regarding "delay time for start of deceleration" and "delay time for start of acceleration" Next, the deceleration start delay time and the acceleration start delay time described above will be specifically explained. The deceleration start delay time is data set for the time counted from when the corrugated sheet is not detected by the lower level sheet detection sensor 88 until the deceleration of the ascending speed of the NO7 wrap conveyor 17 is started in the stage of operation (iii). The acceleration start delay time is data set for the time counted from when the corrugated sheet is detected by the upper level sheet detection sensor 89 until the acceleration of the ascending speed of the NO7 wrap conveyor 17 is started in the stage of operation (iii).

[0081] These deceleration start delay time and acceleration start delay time are provided to prevent the misdetection of the sheet detection sensors 88 and 89 from adversely affecting the stacking of the corrugated sheets. For example, when the upper surface level of the uppermost sheet S1 is near the optical axis of the lower level sheet detection sensor 88, the sensor may misdetect due to the influence of machine vibration or the like (this phenomenon is called "chattering"). Here, if the deceleration start delay time is not provided and the ascending speed of the NO7 wrap conveyor 17 is decelerated immediately when the lower level sheet detection sensor 88 detects no sheet, if this is a misdetection, there is a risk that the drop D will fluctuate and the loading will be disrupted due to unnecessary deceleration. The upper level sheet detection sensor 89 may also chatter, and in that case, if the acceleration start delay time is not provided, the same problem as above may occur.

[0082] For these reasons, in the present embodiment, the control device 100 provides a deceleration start delay time and an acceleration start delay time, and corrects the basic ascending speed at the stage where it can be confirmed that the reaction of the sensor is stable without change and that the reaction is a correct reaction while counting these times. On the other hand, when the reaction of the sensor changes during counting (that is, when the reaction of the sensor is a misdetection), the control device 100 resets the count up to that point.

[0083] Note that the deceleration start delay time and the acceleration start delay time may be set to a uniform time regardless of the production conditions, or may be set to different times according to the production conditions. However, if these set times are too long, during the time counting, the upper surface level of the uppermost sheet S1 may drop further below the lower level or rise further above the upper level, which may prevent the corrugated sheet from being loaded. Therefore, it is advisable to set the deceleration start delay time and the acceleration start delay time to relatively short times that can determine false detections by the sensor.

[0084] Regarding "delay time for end of deceleration" and "delay time for end of acceleration" Next, the deceleration end delay time and the acceleration end delay time described above will be specifically explained. The deceleration end delay time is data set for the time counted from when the detection of the corrugated sheet by the lower level sheet detection sensor 88 after the deceleration of the rising speed of the NO7 wrap conveyor 17 is started in the stage of operation (iii) until the deceleration is completed. The acceleration end delay time is data set for the time counted from when the upper level sheet detection sensor 89 becomes undetected after the acceleration of the rising speed of the NO7 wrap conveyor 17 is started in the stage of operation (iii) until the acceleration of the rising speed of the NO7 wrap conveyor 17 is completed.

[0085] These deceleration end delay times and acceleration end delay times, similar to the deceleration start delay time and acceleration start delay time, are also aimed at preventing adverse effects caused by misdetection of the sheet detection sensors 88 and 89. When the response of the sensor changes during counting, the previous count is reset. In particular, regarding the deceleration end delay time and acceleration end delay time, since the drop D at the time when the correction of the rising speed is completed and the speed returns to the basic rising speed is maintained thereafter, it is desirable that when the counting of these times is completed, the upper surface level of the uppermost sheet S1 reaches the target level exactly (that is, the drop D reaches the target value). Therefore, in the present embodiment, the control device 100 performs lifting control so that the relative rising amount of the upper surface level during the deceleration end delay time matches the height difference between the lower level and the target level, and performs lifting control so that the relative descending amount of the upper surface level during the acceleration end delay time matches the height difference between the upper level and the target level.

[0086] First, referring to FIG. 9, the deceleration end delay time will be described in detail. In each of the left and right diagrams of FIG. 9, the positions of the upper surface levels of the uppermost sheet S1 at the start and completion of counting of the deceleration end delay time are shown. In the stage of operation (iii), since the NO7 lap conveyor 17 is rising and the target level is also rising, the relative rising amount of the upper surface level during the deceleration end delay time is represented by Equation (7). Relative rising amount of upper surface level during deceleration end delay time (mm) = Absolute rising amount of upper surface level during deceleration end delay time (mm) - Rising amount of NO7 lap conveyor during deceleration end delay time (mm) = Increase in sheet loading amount during deceleration end delay time (mm) - Rising amount of NO7 lap conveyor during deceleration end delay time (mm) = Sheet loading increase speed (mm / second) × Deceleration end delay time (seconds) - Corrected rising speed of NO7 lap conveyor (mm / second) × Deceleration end delay time (seconds) Equation (7)

[0087] The corrected rising speed of the NO7 wrap conveyor in Equation (7) is represented by Equation (8) based on the above Equations (5) and (6). Corrected rising speed of the NO7 wrap conveyor (mm / second) = Sheet loading acceleration (mm / second) × correction coefficient = Conveying speed of the NO7 wrap conveyor (mm / second) ÷ Distance between the rear ends of the corrugated sheets on the NO7 wrap conveyor (mm) × Sheet thickness (mm / sheet) × correction coefficient Equation (8)

[0088] As shown in Equation (8), the sheet loading acceleration and the corrected rising speed of the NO7 wrap conveyor 17 will vary depending on the conveying speed of the NO7 wrap conveyor 17 and the distance between the rear ends of the corrugated sheets on the NO7 wrap conveyor 17. Therefore, in this embodiment, even if the sheet loading increase amount and the corrected rising speed of the NO7 wrap conveyor 17 vary depending on the production conditions, the relative rising amount of the upper surface level during the deceleration end delay time is the same, and furthermore, the deceleration end delay time is set so that the rising amount matches the height difference between the lower level and the target level. Specifically, the greater the conveying speed of the NO7 wrap conveyor 17 and the shorter the cutting length of the corrugated sheet, the greater the sheet loading increase speed and the corrected rising speed of the NO7 wrap conveyor 17, so the deceleration end delay time is set shorter accordingly.

[0089] Subsequently, with reference to FIG. 10, the acceleration end delay time will be described in detail. In each of the left and right figures of FIG. 10, the positions of the upper surface levels of the uppermost sheet S1 at the start and completion of counting of the acceleration end delay time are shown. The relative rising amount of the upper surface level during the acceleration end delay time is represented by Equation (9). Relative descending amount of the upper surface level during the acceleration end delay time (mm) = Rising amount of the NO7 wrap conveyor during the acceleration end delay time (mm) - Absolute rising amount of the upper surface level during the acceleration end delay time (mm) = Rising amount of the NO7 wrap conveyor during the acceleration end delay time (mm) - Increase amount of the sheets loaded during the acceleration end delay time (mm) =Correction rising speed of NO7 wrap conveyor (mm / sec) × Acceleration end delay time (sec) - Sheet loading acceleration (mm / sec) × Acceleration end delay time (sec) Formula (9)

[0090] In this embodiment, even if the sheet loading acceleration and the correction rising speed of the NO7 wrap conveyor 17 vary depending on the production conditions, the relative decrease in the upper surface level during the acceleration end delay time is the same, and further, the acceleration end delay time is set so that the decrease amount matches the height difference between the upper level and the target level. Specifically, the greater the conveyance speed of the NO7 wrap conveyor 17 and the shorter the cut length of the corrugated sheet, the greater the sheet loading acceleration and the correction rising speed of the NO7 wrap conveyor 17. Therefore, the acceleration end delay time is set shorter accordingly.

[0091] <Function and Effect> Next, the function and effect of the stacker device 1 according to the above-described embodiment will be described.

[0092] According to this embodiment, the control device 100 of the stacker device 1 controls the lifting of the NO7 wrap conveyor 17 so that the drop D between the conveyance surface of the NO7 wrap conveyor 17 on which the conveyed corrugated sheet is placed and the upper surface of the uppermost sheet S1 on the support table 26 becomes smaller as the weight of the corrugated sheet produced in the corrugator line increases. Thereby, without causing problems such as damaging the corrugated sheet or jamming it, the corrugated sheets produced under various order conditions can be accurately aligned and stacked on the support table 26.

[0093] Specifically, according to this embodiment, first, the corrugated sheets with a large weight are stacked on the support table 26 in a state where the drop D is small. As a result, for the corrugated sheets with a large weight discharged from the NO7 wrapping conveyor 17, when the front end portion of the corrugated sheet that has passed through the outlet of the NO7 wrapping conveyor 17 and is no longer supported by anything tilts downward, the sagging portion can be accurately brought into contact with the upper surface of the uppermost sheet S1 loaded immediately below. Then, while receiving the frictional force in the direction opposite to the traveling direction generated at the contact surface with the uppermost sheet S1, the corrugated sheet is sent out from the NO7 wrapping conveyor 17 and slides on the upper surface of the uppermost sheet S1. As a result, for the corrugated sheets with a large weight, before reaching the stopper 76, they are decelerated by the frictional force and their kinetic energy decreases, so that they do not collide forcefully when reaching the stopper 76, and the backward displacement due to the reaction of the collision can be suppressed. Further, according to this embodiment, since a special mechanism (such as a pressing roll described in Patent Document 2) for decelerating the corrugated sheet is not used, the device configuration can be simplified, and problems such as damaging or jamming the corrugated sheet can be suppressed.

[0094] On the other hand, according to this embodiment, the corrugated sheets with a small weight are stacked on the support table 26 in a state where the drop D is large. As a result, for the corrugated sheets with a small weight, the period (distance) of contacting the uppermost sheet S1 and receiving the frictional force can be shortened, or the corrugated sheet can be sent out without contacting the uppermost sheet S1 and without receiving the frictional force. As a result, the corrugated sheets with a small weight can surely reach the stopper 76. For the corrugated sheets with a small weight, conversely to this embodiment, if the drop D is reduced and the upper surface of the uppermost sheet S1 is slid to receive the frictional force, since the kinetic energy originally possessed by the corrugated sheet is small, the corrugated sheet may stop before reaching the stopper 76 and may not be loaded at an appropriate position.

[0095] As described above, according to this embodiment, by setting an appropriate drop D according to the production conditions of the cardboard sheet and adjusting the period (distance) during which the cardboard sheet discharged from the NO7 wrap conveyor 17 receives frictional force from the uppermost sheet S1 on the support table 26, it is possible to accurately align and stack the cardboard sheets produced under various order conditions on the support table 26.

[0096] Further, according to this embodiment, the control device 100 is configured to perform lifting control so as to maintain the drop D at a target value according to the weight of the cardboard sheet produced on the corrugator line, and the target value is set to a smaller value as the weight of the cardboard sheet is larger. Thereby, during the production of the cardboard sheet, the drop D can be accurately maintained at a target value suitable for the weight of the cardboard sheet by the lifting control of the NO7 wrap conveyor 17.

[0097] Further, according to this embodiment, the target value of the drop D is set according to the flute of the cardboard sheet produced on the corrugator line. In this embodiment, assuming that the weight of the cardboard sheet corresponds to the flute of the cardboard sheet, the target value of the drop D is set according to the flute. Thereby, the control configuration can be simplified as compared with the case where the target value is set by directly judging the weight of the cardboard sheet to be produced.

[0098] Further, according to this embodiment, the target value of the drop D is set according to the dimensions of the cardboard sheet produced on the corrugator line. In this embodiment, assuming that the weight of the cardboard sheet corresponds to the dimensions of the cardboard sheet, the target value of the drop D is set according to the dimensions of the cardboard sheet. Thereby, the control configuration can be simplified as compared with the case where the target value is set by directly judging the weight of the cardboard sheet to be produced.

[0099] Further, according to the present embodiment, when the drop D becomes larger than the target value, the control device 100 performs lifting control to decelerate the rising speed of the NO7 wrap conveyor 17 so as to return the drop D to the target value. As a result, when the drop D becomes larger than the target value, the drop D can be returned to the target value and the target value can be accurately maintained.

[0100] Further, according to the present embodiment, when the drop D becomes smaller than the target value, the control device 100 performs lifting control to accelerate the rising speed of the NO7 wrap conveyor 17 so as to return the drop D to the target value. As a result, when the drop D becomes smaller than the target value, the drop D can be returned to the target value and the target value can be accurately maintained.

[0101] Further, according to the present embodiment, the stacker device 1 further includes a lower level sheet detection sensor 88 that detects the height level (lower level) of the corrugated sheets stacked on the support table 26. The control device 100 determines whether the drop D has become larger than the target value based on the detection result of the lower level sheet detection sensor 88, and after a predetermined time has elapsed since it was determined that the drop D has become larger than the target value, starts lifting control to decelerate the rising speed of the NO7 wrap conveyor 17. In this embodiment, the deceleration of the rising speed of the NO7 wrap conveyor 17 is not started immediately when it is determined that the drop D has become larger than the target value, but the deceleration of the rising speed of the NO7 wrap conveyor 17 is started after a certain period of time has elapsed since this determination. This can prevent the misdetection of the lower level sheet detection sensor 88 from adversely affecting the stacking of the corrugated sheets.

[0102] Further, according to this embodiment, the stacker device 1 further includes an upper level sheet detection sensor 89 that detects the height level (upper level) of the corrugated sheet stacked on the support table 26. The control device 100 determines whether or not the drop D has become smaller than the target value based on the detection result of the upper level sheet detection sensor 89. After a predetermined time has elapsed since it is determined that the drop D has become smaller than the target value, lifting control for accelerating the rising speed of the NO7 wrap conveyor 17 is started. In this embodiment, when it is determined that the drop D has become smaller than the target value, the acceleration of the rising speed of the NO7 wrap conveyor 17 is not started immediately, but is started after a certain period of time has elapsed since this determination. Thereby, it is possible to prevent the misdetection of the upper level sheet detection sensor 89 from adversely affecting the stacking of the corrugated sheets.

[0103] <Modification Example> Next, a modification example of the above-described embodiment will be described.

[0104] (Modification Example 1) In the above-described embodiment, two sheet detection sensors 88 and 89 that detect two height levels, i.e., the lower level and the upper level, are used. However, in the modification example, three or more sheet detection sensors that detect three or more height levels may be used. In this modification example, among the three or more sheet detection sensors, the sensors used for lower level detection and upper level detection may be switched for each flute.

[0105] Also, in another modification example, a sheet detection sensor capable of directly detecting the height level corresponding to the target level for each flute, that is, a plurality of sheet detection sensors capable of detecting each of a plurality of target levels, may be used, and the applicable sensors may be switched for each flute. According to this modification example, at the stage of the above operations (ii) and (iii), when the sheet detection sensor detects the corrugated sheet, it can be determined that the upper surface level has reached the target level, and the rising operation of the NO7 wrap conveyor 17 can be controlled.

[0106] However, since the above-described embodiment can be implemented by two sheet detection sensors, it is advantageous in terms of reducing equipment costs and enabling fine adjustment of the drop by finely adjusting each set time, compared to using three or more sheet detection sensors. Furthermore, in another modification, without using a sheet detection sensor, at the stage of the above operation (ii), the increase in the amount of sheets loaded immediately after the start of production is obtained, and when the increase in the amount of sheets loaded matches the height difference between the upper surface of the pallet 28 and the target level, it may be determined that the upper surface level has reached the target level, and the upward movement of the NO7 wrap conveyor 17 may be controlled.

[0107] (Modification 2) In the above-described embodiment, the target level was set according to the flute, but in the modification, in addition to the flute, or instead of the flute, the target level may be set according to the dimensions of the corrugated sheet (length in the conveying direction and / or width direction). When setting the target level according to the dimensions of the corrugated sheet, it is advisable to consider the following two viewpoints.

[0108] The first viewpoint relates to the weight of the corrugated sheet. The longer the dimensions of the corrugated sheet, the larger the area and weight of the corrugated sheet, and the greater the kinetic energy of the corrugated sheet when it is discharged from the NO7 wrap conveyor 17. Therefore, the first viewpoint is to set the target level upward and reduce the target value of the drop D in order to sufficiently decelerate the corrugated sheet when the dimensions of the corrugated sheet are long.

[0109] The second aspect relates to the dimensions of the cardboard sheet, particularly the length in the conveying direction (the sheet cutting length by cutter 2). The longer the length of the cardboard sheet in the conveying direction, the more likely the front end portion of the cardboard sheet passing through the outlet of the NO7 wrapping conveyor 17 will droop and come into contact with the upper surface of the topmost sheet. In addition, since the distance from the outlet of the NO7 wrapping conveyor 17 to the stopper 76 is long, the distance (time) for the cardboard sheet discharged from the NO7 wrapping conveyor 17 to contact the upper surface of the topmost sheet becomes long, and the cardboard sheet is likely to decelerate. Therefore, the second aspect is that when the length of the cardboard sheet in the conveying direction is long, in order to ensure that this cardboard sheet reaches the stopper 76, the target level is set downward to increase the target value of the drop D.

[0110] In the modification example of setting the target level according to the dimensions of the cardboard sheet in this way, it is advisable to perform experiments, simulations, etc. in advance to set the target level so that the balance between these two aspects can be achieved. For example, when the length of the cardboard sheet in the conveying direction is relatively long, the second aspect may be prioritized over the first aspect, and the target level may be set downward to increase the target value of the drop D (that is, in this case, the target level obtained by changing the target level according to the weight of the cardboard sheet downward is used). Thereby, it is possible to ensure that the cardboard sheet with a long conveying direction length reaches the stopper 76.

[0111] (Modification Example 3) In the above-described embodiment, time was set as the waiting time for the start of ascent, the delay time for the start of deceleration / acceleration, and the delay time for the end of deceleration / acceleration. However, in the modification example, the conveying distance of the NO7 wrapping conveyor 17 may be set instead of time. In this modification example, at the same timing as in the above-described embodiment, the waiting distance for the start of ascent, the delay distance for the start of deceleration / acceleration, and the delay distance for the end of deceleration / acceleration are read out, the counting of the conveying amount of the NO7 wrapping conveyor 17 is started, and when the counted conveying amount matches the set distance, the same control may be performed.

[0112] In another modification example, the number of corrugated sheets discharged from the NO7 wrapping conveyor 17 may be set. In this modification example, at the same timing as in the above-described embodiment, the number of sheets waiting for the start of ascent, the number of sheets delaying the start of deceleration / acceleration, and the number of sheets delaying the end of deceleration / acceleration are read, and the counting of the conveyance amount of the NO7 wrapping conveyor 17 is started. At the same time, the distance between the rear ends of the corrugated sheets on the NO7 wrapping conveyor 17 is read, and when the number of sheets calculated by "the number of sheets discharged from the NO7 wrapping conveyor (sheets) = the conveyance amount of the NO7 wrapping conveyor (mm) ÷ the distance between the rear ends of the corrugated sheets on the NO7 wrapping conveyor (mm / sheet)" matches the set number of sheets, the same control may be performed.

[0113] In any of the above modification examples, even if the sheet loading acceleration speed or the ascending speed of the NO7 wrapping conveyor 17 varies depending on the production conditions, each value may be set so that the relative movement amount of the upper surface level during counting is the same.

[0114] (Modification Example 4) In the above-described embodiment, since the drop D (in this case, the drop D is the height difference between the conveyance surface of the NO7 wrapping conveyor 17 and the upper surface of the pallet 28) is larger than the target value at the start of production, as the corrugated sheet is loaded onto the pallet 28, the ascent of the NO7 wrapping conveyor 17 is stopped until the drop D reaches the target value (that is, until the upper surface level of the uppermost sheet S1 reaches the target level). Therefore, in this embodiment, the ascent of the NO7 wrapping conveyor 17 is started when the drop D reaches the target value. On the other hand, in the modification example, the drop D is set to the target value at the start of production (for example, the NO7 wrapping conveyor 17 is set to the height level corresponding to the target value at the start of production), and from the start of this production, the ascent of the NO7 wrapping conveyor 17 is started, and the elevation control of the NO7 wrapping conveyor 17 may be performed so as to maintain the drop D at the target value. In this modification example, it may be started from operation (iii) without performing operations (i) and (ii).

[0115] (Modification Example 5) The above-described embodiment applied the present invention to an up-stacker device, but the present invention is also applicable to a down-stacker device and an up-down-stacker device. For example, in a modified example where the present invention is applied to a down-stacker device, control for lowering the support table 26 (the same lifting control as in the above-described embodiment) may be performed so as to maintain the drop D at a target value. Further, in this modified example, when the drop D becomes larger than the target value, the lowering speed of the support table 26 may be decelerated, and when the drop D becomes smaller than the target value, the lowering speed of the support table 26 may be accelerated.

Explanation of Signs

[0116] 1 Stacker device 2 Cutter 8 Conveyor 11 NO1 Wrap conveyor 12 NO2 Wrap conveyor 13 NO3 Wrap conveyor 14 NO4 Wrap conveyor 15 NO5 Wrap conveyor 16 NO6 Wrap conveyor 17 NO7 Wrap conveyor 26 Support table 28 Pallet 30 Lifting frame 76 Stopper 88 Lower level sheet detection sensor 89 Upper level sheet detection sensor 100 Control device 128 Motor for lifting the lifting frame D Drop S1 Topmost sheet

Claims

1. A stacker device provided at the end of a corrugator line for stacking cardboard sheets continuously supplied along this line, a plurality of conveyors for conveying the cardboard sheets cut by a cutter to the downstream side, a support table for stacking the cardboard sheets discharged from the most downstream conveyor among the plurality of conveyors, a stopper provided on the support table against which the front end of the cardboard sheet discharged from the most downstream conveyor abuts, a lifting mechanism configured to be able to raise and lower the most downstream conveyor and / or the support table, a control device configured to perform lifting control for raising and lowering the most downstream conveyor and / or the support table by controlling the lifting mechanism, having, the control device is configured to perform the lifting control so that the greater the weight of the cardboard sheet produced in the corrugator line, the smaller the drop between the conveying surface of the most downstream conveyor on which the conveyed cardboard sheet is placed and the upper surface of the uppermost cardboard sheet on the support table, a stacker device characterized by this.

2. The control device is configured to perform the lifting control so as to maintain the drop at a target value according to the weight of the cardboard sheet produced in the corrugator line, the target value is set to a smaller value as the weight of the cardboard sheet is greater, The stacker device according to claim 1.

3. The stacker device according to claim 2, wherein the target value is set according to the flute of the cardboard sheet produced in the corrugator line.

4. The stacker device according to claim 2 or 3, wherein the target value is set according to the dimensions of the cardboard sheet produced in the corrugator line.

5. The stacker device according to claim 4, wherein the target value is set to a larger value as the length along the conveying direction of the cardboard sheet produced in the corrugator line is longer.

6. The control device is configured to perform the lifting control for decelerating the rising speed of the most downstream conveyor and / or the lowering speed of the support table so as to return the drop to the target value when the drop becomes larger than the target value, the stacker device according to claim 2.

7. The stacking device according to claim 2, wherein the control device is configured to perform the lifting control for accelerating the rising speed of the lowermost conveyor and / or the lowering speed of the support table so as to return the drop to the target value when the drop becomes smaller than the target value.

8. The stacking device further includes a sheet detection sensor for detecting the height level of the corrugated sheet stacked on the support table. The stacking device according to claim 6, wherein the control device determines whether the drop has become larger than the target value based on the detection result of the sheet detection sensor, and starts the lifting control for decelerating the rising speed of the lowermost conveyor and / or the lowering speed of the support table after a predetermined time has elapsed since it was determined that the drop has become larger than the target value.

9. The stacking device further includes a sheet detection sensor for detecting the height level of the corrugated sheet stacked on the support table. The stacking device according to claim 7, wherein the control device determines whether the drop has become smaller than the target value based on the detection result of the sheet detection sensor, and starts the lifting control for accelerating the rising speed of the lowermost conveyor and / or the lowering speed of the support table after a predetermined time has elapsed since it was determined that the drop has become smaller than the target value.

10. The stacking device starts production of a corrugated sheet on the corrugator line in a state where the drop is larger than the target value, and further includes a sheet detection sensor for detecting the height level of the corrugated sheet stacked on the support table. The sheet detection sensor is provided at a position capable of detecting a height level corresponding to the target value or a height level lower than the height level. The control device When production of a corrugated sheet starts on the corrugator line and the corrugated sheet starts to be stacked on the support table, based on the detection result of the sheet detection sensor, it determines whether the drop has reached the target value. Continue to stop the lifting of the lowermost conveyor and the support table until it is determined that the drop has reached the target value. When it is determined that the drop has reached the target value, perform the lifting control of the lowermost conveyor and / or the support table so as to maintain the drop at the target value. It is configured as follows. The stacker device according to claim 2.

11. A control method for a stacker device that is provided at the end of a corrugator line and stacks corrugated sheets continuously supplied along this line, wherein the stacker device comprises a plurality of conveyors for transporting the corrugated sheets cut by a cutter to the downstream side, a support table for stacking the corrugated sheets discharged from the most downstream conveyor among the plurality of conveyors, a stopper provided on the support table and against which the front end of the corrugated sheet discharged from the most downstream conveyor abuts, a lifting mechanism configured to be able to lift and lower the most downstream conveyor and / or the support table, a control device configured to perform lifting control for lifting and lowering the most downstream conveyor and / or the support table by controlling the lifting mechanism, and the control method of the stacker device includes a step of performing the lifting control by the control device so that the greater the weight of the corrugated sheet produced in the corrugator line, the smaller the drop between the transport surface of the most downstream conveyor on which the transported corrugated sheet is placed and the upper surface of the uppermost corrugated sheet on the support table. A control method for a stacker device, characterized by this.

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