JP2020116818A - Gluing device for joint margin of corrugated cardboard box - Google Patents

Abstract

To provide a gluing device for a joint margin of a corrugated board box capable of discharging paste by a glue gun at a stable timing so as not to cause inner surface adhesion regardless of a warped state of a blank sheet.SOLUTION: In the gluing device for the joint margin of a corrugated board box, the front end margin length S1 from the front end edge 2a of the joint margin 2 to the front end of the glue line 13 is calculated on the basis of image data of the joint margin 2 photographed by a glue camera 6, and feedback control for changing a discharge start timing distance is performed on the basis of a difference between the calculated front end margin S1 and a preset front edge margin target length.SELECTED DRAWING: Figure 4

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a corrugated box seaming margin gluing device for gluing a blank sheet seam margin of a corrugated box.

In a box making machine that manufactures corrugated cardboard boxes, generally, after printing on a rectangular corrugated cardboard sheet, a notch groove and ruled lines are formed to form a blank sheet, and a splice provided at one end of the blank sheet. Instead, glue is applied with a gluing device, and then the blank sheet is folded into an annular shape to join the joint margin to the other end of the blank sheet, thereby obtaining a cardboard box before assembly.

The gluing device installed in this box making machine is of the glue roller type (that is, the glue roller with the glue adhered to the outer periphery is rotated at a fixed position, and the margin of the blank sheet being conveyed is transferred to the outer periphery of the glue roller. It is roughly classified into two types: one that is glued by contacting it) and one that is glue gun type (that is, glue is ejected from the glue gun provided at a fixed position to the joint margin of the blank sheet being conveyed). It

In the gluing device of the glue roller type, the glue roller continuously contacts and glues over the entire length of the seam allowance, so there is a margin allowance (no glue is applied between the front end edge and the rear end edge of the seam allowance and the glued portion). There is no margin, and the inner surface is adhered (the blank sheet is folded into an annular shape, and when the joint margin is joined to the other end of the blank sheet, the glue protrudes from the joint margin, and the blank that is folded into an annular shape by the protruding glue. There is a problem in that the phenomenon in which the inner surfaces of the sheets adhere to each other tends to occur. On the other hand, in the glue gun type gluing device, a margin for not gluing can be provided between the front end edge and the rear edge of the joint margin and the gluing portion by adjusting the timing of discharging the glue. However, there is an advantage that the inner surface adhesion is unlikely to occur.

As a glue gun type gluing device, for example, the one described in Patent Document 1 is known. As shown in FIG. 1 of the same document, the gluing device of Patent Document 1 is a sheet conveying device that conveys blank sheets of a corrugated cardboard box with a gap between adjacent blank sheets in the front-back direction of the traveling direction, A glue gun that forms a glue line that extends in the direction of travel of the blank sheet on the surface of the seam by ejecting glue to the seam of the blank sheet being conveyed by the sheet conveying device, and the upstream side of the glue gun in the direction of travel of the blank sheet. With a sheet detection sensor that detects the passage of the joint margin, a traveling distance sensor that detects the traveling distance of the blank sheet being conveyed by the sheet conveying device, and an output signal of the sheet detection sensor and an output signal of the traveling distance sensor. And a control unit for controlling the operation of the glue gun based on the above.

This control unit starts integration of the traveling distance when the sheet detection sensor detects that the front edge of the seam margin of the blank sheet has arrived, and the integrated value of the traveling distance reaches a predetermined ejection start timing distance. Occasionally, control is performed to start the discharge of glue by the glue gun. By this control, the front end margin length from the front end edge of the joint margin to the front end of the glue line is theoretically constant.

JP, 10-156974, A

The inventors of the present application start integration of the traveling distance when the sheet detection sensor detects that the front edge of the joint margin of the blank sheet has arrived, as in Patent Document 1, and the integrated value of the traveling distance is An in-house evaluation of a gluing device that started gluing with a glue gun when the specified ejection start timing distance was reached revealed that the actual margin from the leading edge of the seam margin to the leading edge of the glue line There was a problem that the length was not completely constant and the front end of the glue line was too close to the front end edge of the seam margin, so that inner surface adhesion might occur.

Then, the inventors of the present application investigated the cause that the front end margin length from the front end edge of the seam allowance to the front end of the glue line was not constant, and found that the warp of the blank sheet had an effect.

That is, the operating speed of the box making machine is increasing year by year, and is currently about 250 to 400 sheets/minute. Therefore, when the glue is ejected from the glue gun to the joint margin of the blank sheet, the glue gun ejects the glue toward the moving blank sheet at a high speed of about 250 m/min to 400 m/min. Therefore, even if the discharge timing of the glue gun is changed even slightly, the front end margin length from the front end edge of the seam margin of the blank sheet to the front end of the glue line is greatly changed.

On the other hand, a corrugated cardboard sheet, which is the basis of the blank sheet, generally has a three-layer structure including a corrugated middle shin, a front liner bonded to the front side of the middle shin, and a back liner bonded to the back side of the middle shin. Therefore, warpage occurs due to a difference in water content between the front side and the back side. The warp of the corrugated board sheet changes depending on the grade and basis weight of the corrugated board base paper, the ambient environment such as temperature and humidity, and further, the warped state evaporates the moisture of the corrugated board sheet or lowers the surface temperature of the corrugated board sheet. As a result, the corrugated board sheet changes with time immediately after being manufactured by the corrugator and before being supplied to the box making machine. The warp of the corrugated board sheet directly becomes the warp of the blank board of the corrugated board box, which leads to a slight error in the detection timing of the blank sheet by the sheet detection sensor.

Then, a slight error in the detection timing of the sheet detection sensor due to the warp of the blank sheet slightly changes the discharge timing of the glue gun, and the front end margin length from the front edge of the seam margin of the blank sheet to the front end of the glue line is changed. Turned out to be unstable.

Here, in order to deal with the above-mentioned problem that the front end margin length from the front end edge of the seam margin of the blank sheet to the front end of the glue line becomes unstable, an operator periodically visually checks the front end margin length. It is also possible to take a countermeasure such as checking the operator and manually adjusting the discharge timing of the glue gun when the front end margin length largely deviates from the target value.However, in this countermeasure, as described above, Since the operating speed of the box making machine is as high as about 250 sheets/minute to 400 sheets/minute, when a worker finds that the front end margin length is largely deviated from the target value, it has already been applied to many blank sheets. Gluing has been completed and it is not possible to prevent internal adhesion.

The problem to be solved by the present invention is to apply the glue in the seam allowance of the corrugated cardboard box that can discharge the glue with a stable timing so that the inner surface adhesion does not occur regardless of the warp state of the blank sheet. It is to provide a device.

In order to solve the above problems, the present invention provides a corrugated box gluing device for a corrugated box having the following configuration.
That is, a sheet conveying device that conveys a blank sheet of a cardboard box with a space between the blank sheets that are adjacent to each other in the front-rear direction,
The surface of the seam allowance is provided so as to face the region through which the seam allowance of the end portion in the direction orthogonal to the traveling direction of the blank sheet being conveyed by the sheet conveying device passes, and the glue is discharged to the seam allowance. A glue gun for forming a glue line extending in the traveling direction of the blank sheet,
A sheet detection sensor that detects the presence or absence of passage of the joint margin on the upstream side in the traveling direction of the blank sheet with respect to the glue gun,
A traveling distance sensor that detects a traveling distance of the blank sheet being conveyed by the sheet conveying device,
A glue camera for photographing the surface of the seam margin on the downstream side in the traveling direction of the blank sheet with respect to the glue gun,
A control unit that controls the operation of the glue gun based on the output signal of the sheet detection sensor, the output signal of the traveling distance sensor, and the output signal of the glue camera;
The control unit is
When the sheet detection sensor detects that the front edge of the seam margin of the blank sheet has arrived, the integration of the traveling distance is started, and when the integrated value of the traveling distance reaches a predetermined ejection start timing distance. Discharge start timing control means for controlling the discharge of glue by the glue gun,
Front end margin length calculating means for calculating a front end margin length from a front end edge of the seam allowance to a front end of the glue line based on image data of the seam allowance taken by the glue camera;
Ejection start timing feedback control means for performing feedback control for changing the ejection start timing distance based on a difference between the front end margin length calculated by the front end margin length calculation means and a preset front end margin target length. Has,
Provide a gluing device for a joint margin of a cardboard box.

By doing this, the glue camera photographs the seam margin on the downstream side of the glue gun, and based on the image data of the seam margin taken by the glue camera, the front end margin length from the front edge of the seam margin to the front end of the glue line. Is calculated, and feedback control of the discharge start timing of the glue gun is performed based on the difference between the calculated front edge margin length and the preset front edge margin target length, so the detection timing of the sheet detection sensor due to the warp of the blank sheet When the discharge timing of the glue gun is changed due to the error of (1) and the front end margin length from the front end edge of the seam allowance to the front end of the glue line is changed, the discharge start timing distance is changed in a direction to cancel the change. Therefore, regardless of the warp state of the blank sheet, it is possible to discharge the glue with the glue gun at a stable timing so that the inner surface adhesion does not occur.

The control unit is
When the sheet detection sensor detects that the trailing edge of the joint margin has passed, the integration of the traveling distance is started, and the glue gun is formed when the integrated value of the traveling distance reaches a predetermined ejection end timing distance. Discharge end timing control means for ending the discharge of glue by
A trailing edge margin length calculating means for computing a trailing edge margin length from a trailing edge of the glue line to a trailing edge of the joining margin based on image data of the joining margin taken by the glue camera;
Discharge end timing feedback for performing feedback control for changing the discharge end timing distance based on a difference between the rear end margin length calculated by the rear end margin length calculation means and a preset rear end margin target length. It is preferable to further include a control means.

By doing so, the trailing edge margin length from the trailing edge of the glue line to the trailing edge of the joining margin is calculated based on the image data of the joining margin taken by the glue camera, and the calculated trailing edge margin length and The feedback control of the discharge end timing of the glue gun is performed based on the difference from the preset rear end margin target length, so the discharge timing of the glue gun changes due to the error in the detection timing of the sheet detection sensor due to the warp of the blank sheet. However, when the trailing edge margin length from the trailing edge of the glue line to the trailing edge of the joint margin changes, the ejection end timing distance changes in a direction to cancel the change. Therefore, regardless of the warp state of the blank sheet, it is possible to discharge the glue with the glue gun at a stable timing so that the inner surface adhesion does not occur.

Further provided with a discharge pressure variable mechanism for changing the discharge pressure of the glue of the glue gun,
The control unit is
A glue line thickness calculating means for calculating the thickness of the glue line based on the image data of the seam allowance taken by the glue camera;
Glue line thickness adjustment feedback control means for feedback controlling the discharge pressure variable mechanism based on the difference between the glue line thickness calculated by the glue line thickness calculation means and a preset glue line target thickness. It is preferable to have a configuration further including.

By doing this, the thickness of the glue line is calculated based on the image data of the seam margin taken by the glue camera, and based on the difference between the calculated thickness of the glue line and the preset target glue line thickness. By performing feedback control of the glue gun's glue discharge pressure, when the glue line thickness changes due to changes in glue viscosity and ambient temperature, the glue gun's glue discharge pressure changes in a direction that cancels the change. .. Therefore, it is possible to discharge the glue by the glue gun with a stable discharge amount so as not to cause the inner surface adhesion and the adhesion failure at the joint margin, regardless of the change of the viscosity and the ambient temperature of the glue.

Further provided is a glue gun position adjusting mechanism for moving the glue gun in a direction orthogonal to the traveling direction of the blank sheet,
The control unit is
Outer margin width calculating means for calculating an outer margin width from the glue line to the side edge of the seam based on image data of the seam taken by the glue camera,
A configuration further comprising a glue gun position feedback control means for performing feedback control of the glue gun position adjusting mechanism based on a difference between the outer margin width calculated by the outer margin width calculation means and a preset outer margin target width. Is preferable.

In this way, the outer margin width from the glue line to the side edge of the seam margin is calculated based on the seam margin image data taken by the glue camera, and the outer margin width and the preset outer margin target width are calculated. Since the feedback control of the glue gun position adjustment mechanism is performed based on the difference between and, the conveyance state of the blank sheet changes due to the warp of the blank sheet, and the relative positional relationship between the seam allowance of the blank sheet being conveyed and the glue gun is When the glue gun moves in a direction orthogonal to the traveling direction, the glue gun moves following the change. Therefore, regardless of the warped state of the blank sheet, it is possible to discharge the glue with the glue gun from a stable position so that the inner surface adhesion does not occur.

In the pasting margin gluing device of the cardboard box of the present invention, the glue camera photographs the joint margin on the downstream side of the glue gun, and based on the image data of the joint margin photographed by the glue camera, the front end margin length calculating means is provided. The ejection start timing feedback control means calculates the front end margin length from the front end edge of the joint margin to the front end of the glue line, and based on the difference between the calculated front end margin length and the preset front end margin target length. Since feedback control is performed, when the discharge timing of the glue gun changes due to the error in the detection timing of the sheet detection sensor due to the warp of the blank sheet, and the front end margin length from the front end edge of the seam margin to the front end of the glue line changes. , The ejection start timing distance changes in the direction of canceling the change. Therefore, regardless of the warp state of the blank sheet, it is possible to discharge the glue with the glue gun at a stable timing so that the inner surface adhesion does not occur.

The partial cross-section top view which looked at the gluing device of the joint margin of the corrugated board box of embodiment of this invention from the upper side. 1 is a partial cross-sectional front view of the gluing device shown in FIG. 1 as seen from the downstream side in the traveling direction of the blank sheet. The figure which expands and shows the vicinity of the glue gun of FIG. IV-IV line sectional view of FIG. The figure which expands and shows the vicinity of the glue gun of FIG. FIG. 1 is a perspective view showing a positional relationship among a glue gun, a sheet detection sensor, a glue camera, and a blank sheet of the gluing device shown in FIG. Block diagram of the gluing device shown in FIG. In the gluing device shown in FIG. 1, a perspective view illustrating a state in which the front edge of the seam margin of the blank sheet being conveyed has reached the position of the sheet detection sensor. FIG. 8 is a perspective view illustrating a state in which the blank sheet shown in FIG. 8 has moved to the downstream side and the trailing edge of the seam of the blank sheet has passed the position of the sheet detection sensor. FIG. 9 is a perspective view illustrating a state in which the blank sheet shown in FIG. 9 has moved to the downstream side and the front edge of the seam margin of the blank sheet has reached the position of the glue camera sensor. FIG. 10 is a perspective view illustrating a state in which the blank sheet shown in FIG. 10 has moved to the downstream side, and the front edge of the seam margin of the blank sheet has entered the photographing area of the glue camera. (A) It is an enlarged view of the seam allowance of the blank sheet shown in FIG. 1, (b) It is a figure which shows the other example of the seam allowance, Comprising: The seam which has a fin at the front end and back end of the advancing direction of a blank. Figure showing teenage

FIG. 1 is a view of a gluing device for a joint margin of a corrugated cardboard box according to an embodiment of the present invention, which is incorporated in a box making machine, as viewed from above. The box making machine prints on a rectangular corrugated cardboard sheet with a printing unit (not shown) arranged on the upstream side (upper side in the drawing) of the gluing device, and then cuts a plurality of cut grooves 38 extending in the traveling direction on the corrugated cardboard sheet. A blank sheet 1 is formed by inserting ruled lines 39, and a seaming margin 2 provided at one end of the blank sheet 1 is glued with a gluing device, and then the downstream side of the gluing device (lower side of the figure). ), the joint portion 2 is joined to the other end portion (the left end portion in the figure) of the blank sheet 1 by folding the blank sheet 1 in an annular shape at a folding portion (not shown). You get the box. The joint margin 2 is an elongated projecting piece provided in an end portion (an end portion on the right side in the drawing) orthogonal to the advancing direction of the blank sheet 1 in the advancing direction of the blank sheet 1 (vertical direction in the drawing). It is partitioned by a ruled line 39 from the main body portion of the sheet 1 other than the joint margin 2.

The gluing device conveys the blank sheet 1 of the cardboard box from the upstream side (upper side in the figure) to the downstream side (lower side in the figure) in a state in which there is a space between the blank sheets 1 adjacent to each other in the front-rear direction. Sheet conveying device 3, a glue gun 4 provided to face a region through which the joint margin 2 of the blank sheet 1 being conveyed by the sheet conveying device 3 passes, and an upstream side in the traveling direction of the blank sheet 1 with respect to the glue gun 4. The sheet detection sensor 5 for detecting whether or not the joint margin 2 has passed, and the glue camera 6 for photographing the surface of the joint margin 2 on the downstream side of the glue gun 4 in the traveling direction of the blank sheet 1 (see FIGS. 3 and 4). And a glue gun position adjusting mechanism 7 (see FIG. 2) for moving the glue gun 4 in a direction orthogonal to the traveling direction of the blank sheet 1.

As shown in FIGS. 1 and 2, the sheet conveying device 3 includes an upper folding belt 8 that travels while contacting the upper surface of the blank sheet 1, and a lower folding belt 9 that travels while contacting the lower surface of the blank sheet 1. Have. A traveling distance sensor 10 (see FIG. 7) for detecting a traveling distance of the blank sheet 1 being conveyed by the sheet conveying device 3 is connected to a belt pulley (not shown) around which the upper folding belt 8 or the lower folding belt 9 is wound. ing. The traveling distance sensor 10 is, for example, a rotary encoder connected to the rotation shaft of the belt pulley so as to output a signal according to the rotation angle of the belt pulley.

As shown in FIG. 3, the glue gun 4 is provided at a fixed position above a region through which the joint margin 2 of the blank sheet 1 being conveyed by the sheet conveying device 3 passes. A plurality of glue guns 4 are arranged in a direction orthogonal to the traveling direction of the blank sheet 1 (left-right direction in the drawing). Further, these glue guns 4 are arranged with a gap in the advancing direction of the blank sheet 1 as shown in FIG. 4 so that adjacent glue guns 4 do not interfere with each other. Each glue gun 4 has a built-in electromagnetic opening/closing valve that switches between discharging and stopping the glue. As shown in FIG. 5, each glue gun 4 is fixed to a glue gun support bracket 11. The glue gun support bracket 11 is attached to the movable frame 12 so as to move integrally with the movable frame 12. As shown in FIG. 6, each glue gun 4 forms a glue line 13 extending in the traveling direction of the blank sheet 1 on the surface of the joint margin 2 by discharging the glue to the joint margin 2.

As shown in FIG. 2, the glue gun position adjusting mechanism 7 includes a movable frame 12 supported by a linear guide 14 so as to be movable in a direction orthogonal to the traveling direction of the blank sheet 1, and a nut 15 provided on the movable frame 12. A screw shaft 16 that engages with the nut 15, an electric motor 17 that rotationally drives the screw shaft 16, and a rotation sensor 18 that detects the number of rotations of the screw shaft 16. The screw shaft 16 is arranged so as to extend in a direction orthogonal to the traveling direction of the blank sheet 1, and is supported by the fixed frame 19 so as to be rotatable and immovable in the axial direction.

As shown in FIG. 4, the sheet detection sensor 5 is an optical sensor in which a light emitting element and a light receiving element are vertically opposed to each other with a passage area of the blank sheet 1 interposed therebetween. As shown in FIG. 5, the sheet detection sensor 5 is arranged at a position through which the joint margin 2 of the blank sheet 1 being conveyed by the sheet conveying device 3 passes. The sheet detection sensor 5 is fixed to the sheet detection sensor support bracket 20. The sheet detection sensor support bracket 20 is attached to the movable frame 12 so as to move integrally with the movable frame 12. A second sheet detection sensor 21 is attached to the sheet detection sensor support bracket 20 side by side with the sheet detection sensor 5. The second sheet detection sensor 21 is provided at a position where the main body portion of the blank sheet 1 excluding the joint margin 2 passes.

As shown in FIG. 4, the glue camera 6 is provided at a fixed position above a region through which the joint margin 2 of the blank sheet 1 being conveyed by the sheet conveying device 3 passes. The glue camera 6 may be an area camera that reads an image of a two-dimensional area, or a line camera that reads an image of a linear area orthogonal to the traveling direction of the blank sheet 1. .. The glue camera 6 is fixed to the glue camera support bracket 22. The glue camera support bracket 22 is attached to the movable frame 12 so as to move integrally with the movable frame 12.

A glue camera sensor 23 for detecting the shooting start timing of the glue camera 6 is provided on the upstream side of the glue camera 6. The glue camera sensor 23 is an optical sensor in which a light emitting element and a light receiving element are vertically opposed to each other with a passage area of the blank sheet 1 interposed therebetween. The glue camera sensor 23 is arranged at a position through which the joint margin 2 of the blank sheet 1 being conveyed by the sheet conveying device 3 passes. The glue camera sensor 23 is fixed to the glue camera sensor support bracket 24. The glue camera sensor support bracket 24 is attached to the movable frame 12 so as to move integrally with the movable frame 12. An illumination unit 25 that illuminates the photographing area of the glue camera 6 is attached to the movable frame 12.

As shown in FIG. 3, the sheet detection sensor support bracket 20 is provided with sheet guides 26 that vertically face each other with a passage area of the blank sheet 1 interposed therebetween. The sheet guide 26 guides a portion of the blank sheet 1 that is being conveyed in the vicinity of the sheet detection sensor 5 from above and below to stabilize the detection accuracy of the joint margin 2 by the sheet detection sensor 5. Further, the glue camera sensor support bracket 24 is also provided with sheet guides 27 which are vertically opposed to each other with the passage area of the blank sheet 1 interposed therebetween.

The operation of the glue gun 4 is controlled by the control unit 30 shown in FIG. As shown in FIG. 7, the control unit 30 in this embodiment includes a PLC 31 (programmable logic controller), a camera control unit 32, and a glue gun control unit 33. In the camera control unit 32, the output signal of the glue camera sensor 23 indicating whether or not the joint margin 2 of the blank sheet 1 is at the position of the glue camera sensor 23, the blank sheet 1 being conveyed by the sheet conveying device 3, and the like. The output signal of the traveling distance sensor 10 representing the traveling distance and the output signal of the glue camera 6 representing the image captured by the glue camera 6 are input. The PLC 31 outputs the output signal of the sheet detection sensor 5 indicating whether or not the joint margin 2 of the blank sheet 1 is at the position of the sheet detection sensor 5, and detects the second sheet by the main body portion excluding the joint margin 2 of the blank sheet 1. An output signal of the second sheet detection sensor 21 indicating whether or not the sensor 21 is at the position, an output signal of a traveling distance sensor 10 indicating a traveling distance of the blank sheet 1 being conveyed by the sheet conveying device 3, FIG. Output signals of the camera control unit 32 indicating the front end margin length S1, the rear end margin length S2, the glue line thickness W, and the outer margin width S3 shown in (b) are input. The PLC 31 outputs to the glue gun control unit 33 a control signal for starting and ending the ejection of the glue gun 4, and a control signal for changing the ejection pressure of the glue gun 4. The glue gun control unit 33 drives the glue gun 4 and the discharge pressure varying mechanism 28 based on the control signal output from the PLC 31. The discharge pressure varying mechanism 28 is a mechanism for changing the discharge pressure of the glue of the glue gun 4 according to an electric signal, and, for example, a piston pump that feeds the glue with a piston driven by air pressure, and an air pressure supplied to the piston pump. An electro-pneumatic regulator that changes according to an electric signal can be used. The PLC 31 also drives the electric motor 17 of the glue gun position adjusting mechanism 7.

An example of control by the control unit 30 will be described.

[Discharge start timing control]
As shown in FIG. 8, when the sheet detection sensor 5 detects that the front edge 2a of the seam margin 2 of the blank sheet 1 has reached, the PLC 31 causes the blank detected by the traveling distance sensor 10 (see FIG. 7). Start integration of the traveling distance of the seat 1. At this time, the detection signal of the second sheet detection sensor 21 is used as an interlock signal when the sheet detection sensor 5 detects that the front edge 2a of the joint margin 2 has arrived. That is, even when the sheet detection sensor 5 is turned on, if the second sheet detection sensor 21 is turned off, it is determined that the joint margin 2 of the blank sheet 1 has not reached the position of the sheet detection sensor 5, Only when both the detection sensor 5 and the second sheet detection sensor 21 are turned ON, it is determined that the joint margin 2 of the blank sheet 1 has reached the position of the sheet detection sensor 5, and thus the sheet detection sensor 5 is a scrap. Prevents misjudgment when it is turned on due to such reasons.

Then, as shown in FIG. 9, when the integrated value of the traveling distance of the blank sheet 1 detected by the traveling distance sensor 10 (see FIG. 7) reaches a predetermined ejection start timing distance, the PLC 31 causes the glue gun 4 to move. A signal for starting the discharge of the glue is output to the glue gun control unit 33, and the glue gun 4 starts the discharge of the glue. Here, the discharge start timing distance is such that the formation of the glue line 13 is started with a front end margin (margin allowance) of a predetermined length between the front edge 2a of the joint margin 2 and the front end of the glue line 13 without glue. It is a value set in advance to do so.

[Discharge end timing control]
As shown in FIG. 9, when the sheet detection sensor 5 detects that the trailing edge 2b of the seam allowance 2 has passed, the PLC 31 causes the traveling distance sensor 10 (see FIG. 7) to detect the blank sheet 1 of the blank sheet 1. Start integrating travel distance. Then, as shown in FIG. 10, when the integrated value of the traveling distance of the blank sheet 1 detected by the traveling distance sensor 10 reaches a predetermined ejection end timing distance, the PLC 31 ends the ejection of the glue from the glue gun 4. To the glue gun controller 33, and the glue gun 4 finishes discharging the glue. Here, the discharge end timing distance of the glue line 13 is set with a rear end margin (margin allowance) of a predetermined length between the rear end of the glue line 13 and the rear end edge 2b of the joint margin 2 not to be glued. It is a value preset so that the formation is completed.

[Discharge start timing feedback control]
As shown in FIG. 10, when the glue camera sensor 23 detects that the front edge 2 a of the seam margin 2 of the blank sheet 1 has arrived, the camera control unit 32 causes the glue camera 6 to detect the surface of the seam margin 2. Starts capturing the image data of the captured image. After that, when the glue camera sensor 23 detects that the rear edge 2b of the seam allowance 2 has passed, the camera control unit 32 ends the capture of the image data from the glue camera 6. In this way, the camera control unit 32 acquires the image data of the joint margin 2 photographed by the glue camera 6, as shown in FIG.

Next, the camera control unit 32, based on the image data of the seam allowance 2 taken by the glue camera 6, the front end margin from the front end edge 2a of the seam allowance 2 shown in FIG. The length S1 is calculated. Then, the PLC 31 performs feedback control for changing the ejection start timing distance of each glue gun 4 based on the difference between the front end margin length S1 calculated by the camera control unit 32 and the preset front end margin target length. That is, when the front end margin length S1 of each glue line 13 calculated based on the image data is shorter than the preset front end margin target length, the ejection start timing distance of the corresponding glue gun 4 is increased, and When the front end margin length S1 of each glue line 13 calculated based on the image data is longer than the preset front end margin target length, the ejection start timing distance of the corresponding glue gun 4 is reduced. Perform feedback control.

[Discharge end timing feedback control]
The camera control unit 32 determines the rear end margin length from the rear end of the glue line 13 to the rear end edge 2b of the seam margin 2 shown in FIG. S2 is calculated. Then, the PLC 31 performs feedback control that changes the ejection end timing distance of each glue gun 4 based on the difference between the trailing edge margin length S2 calculated by the camera control unit 32 and the preset trailing edge margin target length. To do. That is, when the trailing edge margin length S2 of each glue line 13 calculated based on the image data is shorter than the preset trailing edge margin target length, the ejection end timing distance of the corresponding glue gun 4 is reduced. On the other hand, when the trailing edge margin length S2 of each glue line 13 calculated based on the image data is longer than the preset trailing edge margin target length, the corresponding ejection end timing distance of the glue gun 4 is set. Feedback control is performed so as to increase.

[Glue thickness adjustment feedback control]
The camera control unit 32 calculates the thickness W of the glue line 13 shown in FIG. 12A based on the image data of the seam allowance 2 taken by the glue camera 6. Then, the PLC 31 feedback-controls the discharge pressure variable mechanism 28 based on the difference between the thickness W of the glue line 13 calculated by the camera control unit 32 and the preset target glue line thickness. That is, when the thickness W of the glue line 13 calculated based on the image data is smaller than the preset target thickness of the glue line 13, the adhesive discharge pressure of the glue gun 4 is increased, while the glue line 13 is based on the image data. When the calculated thickness W of the glue line 13 is thicker than the preset target glue line thickness, feedback control is performed so as to reduce the glue discharge pressure of the glue gun 4.

[Glue gun position feedback control]
The camera control unit 32 calculates the outer margin width S3 from the glue line 13 to the side edge 2c of the seam margin 2 shown in FIG. 12A based on the image data of the seam margin 2 captured by the glue camera 6. Then, the PLC 31 feedback-controls the glue gun position adjusting mechanism 7 based on the difference between the outer margin width S3 calculated by the camera control unit 32 and the preset outer margin target width. That is, when the outer margin width S3 calculated based on the image data is narrower than the preset outer margin target width, the electric motor 17 of the glue gun position adjusting mechanism 7 moves the glue gun 4 inward in the width direction. On the other hand, when the outer margin width S3 calculated based on the image data is wider than the preset outer margin target width, the glue gun position adjusting mechanism 7 moves the glue gun 4 outward in the width direction. Feedback control is performed so as to operate the electric motor 17.

By the way, the box-making machine in which the above-mentioned gluing device is incorporated is operated at an operating speed of about 250 sheets/min to 400 sheets/min. Therefore, when the glue is discharged from the glue gun 4 to the joint margin 2 of the blank sheet 1, the glue gun 4 discharges the glue toward the blank sheet 1 which is moving at a high speed of about 250 m/min to 400 m/min. .. Therefore, even if the ejection timing of the glue gun 4 changes even slightly, the front end margin length S1 from the front end edge 2a of the seam margin 2 of the blank sheet 1 to the front end of the glue line 13 changes greatly.

On the other hand, the corrugated cardboard sheet that is the basis of the blank sheet 1 is warped due to a difference in water content between the front side and the back side. The warp of the corrugated board sheet changes depending on the grade and basis weight of the corrugated board base paper, the ambient environment such as temperature and humidity, and further, the warped state evaporates the moisture of the corrugated board sheet or lowers the surface temperature of the corrugated board sheet. As a result, the corrugated board sheet changes with time immediately after being manufactured by the corrugator and before being supplied to the box making machine. The warp of the corrugated board sheet becomes the warp of the blank sheet 1 as it is, which leads to a slight error in the detection timing of the blank sheet 1 by the sheet detection sensor 5.

Then, a slight error in the detection timing of the sheet detection sensor 5 due to the warp of the blank sheet 1 slightly changes the ejection timing of the glue gun 4, and from the front end edge 2a of the seam margin 2 of the blank sheet 1 to the front end of the glue line 13. The front end margin length S1 is changed. Here, if the front end of the glue line 13 comes too close to the front end edge 2a of the seam allowance 2, inner surface adhesion (when the seam allowance 2 is joined to the other end of the blank sheet 1 by folding the blank sheet 1 in an annular shape) There is a problem in that the glue protrudes from the joint margin 2, and the glue that sticks out causes a phenomenon in which the inner surfaces of the blank sheet 1 folded into a ring adhere to each other.

With respect to this problem, in the above gluing device, the glue camera 6 photographs the joint margin 2 on the downstream side of the glue gun 4, and based on the image data of the joint margin 2 photographed by the glue camera 6, the front end of the joint margin 2 is detected. The front end margin length S1 from the edge 2a to the front end of the glue line 13 is calculated, and the ejection start timing of the glue gun 4 is based on the difference between the calculated front end margin length S1 and the preset front end margin target length. Since the feedback control is performed, the ejection timing of the glue gun 4 changes due to an error in the detection timing of the sheet detection sensor 5 due to the warp of the blank sheet 1, and the front end margin from the front end edge 2a of the seam margin 2 to the front end of the glue line 13 is changed. When the length S1 changes, the ejection start timing distance changes in a direction to cancel the change. Therefore, regardless of the warped state of the blank sheet 1, it is possible to discharge the glue by the glue gun 4 at a stable timing so that the inner surface adhesion does not occur.

Further, this gluing device calculates the rear end margin length S2 from the rear end of the gluing line 13 to the rear end edge 2b of the joint margin 2 based on the image data of the joint margin 2 taken by the glue camera 6. Since the feedback control of the discharge end timing of the glue gun 4 is performed based on the difference between the calculated trailing edge margin length S2 and the preset trailing edge target length, the sheet detection sensor due to the warp of the blank sheet 1 When the ejection timing of the glue gun 4 changes due to an error in the detection timing of 5, and the rear end margin length S2 from the rear end of the glue line 13 to the rear end edge 2b of the joint margin 2 changes, the change is canceled. The discharge end timing distance changes in the direction. Therefore, regardless of the warped state of the blank sheet 1, it is possible to discharge the glue by the glue gun 4 at a stable timing so that the inner surface adhesion does not occur.

Further, this gluing device calculates the thickness W of the glue line 13 based on the image data of the seam allowance 2 taken by the glue camera 6, and sets the calculated thickness W of the glue line 13 in advance. Since the feedback control of the adhesive discharge pressure of the glue gun 4 is performed based on the difference with the target glue line thickness, when the thickness W of the glue line 13 changes due to the viscosity of the glue or the ambient temperature, the change. The discharge pressure of the glue of the glue gun 4 changes in the direction of canceling. Therefore, it is possible to discharge the glue by the glue gun 4 with a stable discharge amount so as not to cause inner surface adhesion or adhesion failure of the joint margin 2, regardless of the viscosity of the glue and changes in the ambient temperature.

The gluing device also calculates the outer margin width S3 from the glue line 13 to the side edge 2c of the seam margin 2 based on the image data of the seam margin 2 captured by the glue camera 6, and then the outer margin width S3. And the feedback control of the glue gun position adjusting mechanism 7 is performed based on the difference between the preset outer margin target width, and therefore, the conveyance state of the blank sheet 1 is changed by the warp of the blank sheet 1, and the blank sheet being conveyed is being changed. When the relative positional relationship between the seam allowance 2 of 1 and the glue gun 4 changes in the direction orthogonal to the traveling direction of the blank sheet 1, the glue gun 4 moves following the change. Therefore, regardless of the warped state of the blank sheet 1, it is possible to discharge the glue by the glue gun 4 from a stable position so that the inner surface adhesion does not occur.

In the above-described embodiment, as shown in FIG. 12A, the length of the joint margin 2 along the traveling direction of the blank sheet 1 is two parallel ruled lines extending in the direction orthogonal to the traveling direction of the blank sheet 1. The case where the blank sheet 1 shorter than the interval of 40 is glued has been described as an example. However, as shown in FIG. 12B, two parallel ruled lines 40 are provided at the front end and the rear end of the seam allowance 2. Similarly, when gluing the blank sheet 1 provided with the fins 41 extending beyond the same, the gluing can be performed.

In the above-described embodiment, the glue camera sensor 23 has the light emitting element and the light receiving element arranged vertically facing each other with the passage area of the blank sheet 1 interposed therebetween. Reference numeral 23 denotes a diffuse reflection type optical sensor provided on the upper side or the lower side of the passing area of the blank sheet 1 (from a light projecting portion that projects light toward the passing area of the blank sheet 1 and the passing area of the blank sheet 1). It is also possible to employ an optical sensor having a light receiving section for receiving the reflected light of the above. Similarly, as the sheet detection sensor 5, it is possible to employ a diffuse reflection type optical sensor provided on the upper side or the lower side of the passage area of the blank sheet 1.

DESCRIPTION OF SYMBOLS 1 blank sheet 2 seam margin 2a front edge 2b rear edge 2c seam margin side edge 3 sheet conveying device 4 glue gun 5 sheet detection sensor 6 glue camera 7 glue gun position adjusting mechanism 10 traveling distance sensor 13 glue line 28 discharge pressure varying mechanism 30 Control unit S1 Front end margin length S2 Rear end margin length S3 Outer margin width W Thickness of glue line

Claims (4)

A sheet conveying device (3) for conveying a blank sheet (1) of a cardboard box in a state in which a space is provided between the blank sheets (1) adjacent to each other before and after in the traveling direction,
The seam allowance (2) is provided so as to face the region through which the seam allowance (2) at the end portion in the direction orthogonal to the traveling direction of the blank sheet (1) being conveyed by the sheet conveying device (3) passes. A glue gun (4) for forming a glue line (13) extending in the traveling direction of the blank sheet (1) on the surface of the seam allowance (2) by discharging glue onto the
A sheet detection sensor (5) for detecting whether or not the joint margin (2) has passed on the upstream side in the traveling direction of the blank sheet (1) with respect to the glue gun (4);
A traveling distance sensor (10) for detecting a traveling distance of the blank sheet (1) being conveyed by the sheet conveying device (3),
A glue camera (6) for photographing the surface of the joint margin (2) on the downstream side of the glue gun (4) in the traveling direction of the blank sheet (1),
A control unit (30) for controlling the operation of the glue gun (4) based on the output signal of the sheet detection sensor (5), the output signal of the traveling distance sensor (10), and the output signal of the glue camera (6). And have,
The control unit (30)
When the sheet detection sensor (5) detects that the front edge (2a) of the seam allowance (2) of the blank sheet (1) has reached, the integration of the traveling distance is started, and the integrated value of the traveling distance. Discharge start timing control means for performing control to start discharge of glue by the glue gun (4) when a predetermined discharge start timing distance is reached.
Based on the image data of the seam allowance (2) taken by the glue camera (6), the front end margin length (from the front end edge (2a) of the seam allowance (2) to the front end of the glue line (13) ( Front end margin length calculation means for calculating S1),
Ejection start timing for performing feedback control for changing the ejection start timing distance based on the difference between the front end margin length (S1) calculated by the front end margin length calculation means and a preset front end margin target length. Feedback control means,
A gluing device for the joint margin of cardboard boxes. The control unit (30)
When the sheet detection sensor (5) detects that the trailing edge (2b) of the seam allowance (2) has passed, the integration of the traveled distance is started, and the integrated value of the traveled distance ends the predetermined discharge. Discharge end timing control means for ending the discharge of glue by the glue gun (4) when the timing distance is reached,
A rear end margin from the rear end of the glue line (13) to the rear end edge (2b) of the seam margin (2) based on the image data of the seam margin (2) taken by the glue camera (6). A rear end margin length calculating means for calculating the length (S2),
Feedback control for changing the discharge end timing distance is performed based on the difference between the trailing edge margin length (S2) calculated by the trailing edge margin length calculating means and a preset trailing edge margin target length. And a discharge end timing feedback control means,
The gluing device for the joint margin of the cardboard box according to claim 1. A discharge pressure varying mechanism (28) for changing the discharge pressure of the glue of the glue gun (4),
The control unit (30)
Glue line thickness calculating means for calculating the thickness (W) of the glue line (13) based on the image data of the seam allowance (2) taken by the glue camera (6);
Feedback control of the discharge pressure variable mechanism (28) is performed based on the difference between the thickness (W) of the glue line (13) calculated by the glue line thickness calculation means and a preset target glue line thickness. Further comprising a glue line thickness adjustment feedback control means,
The gluing device for the joint margin of the cardboard box according to claim 1 or 2. Further comprising a glue gun position adjusting mechanism (7) for moving the glue gun (4) in a direction orthogonal to the traveling direction of the blank sheet (1),
The control unit (30)
The outer margin width (S3) from the glue line (13) to the side edge (2c) of the seam margin (2) is determined based on the image data of the seam margin (2) taken by the glue camera (6). Outer margin width calculating means for calculating,
A glue gun position feedback control means for feedback controlling the glue gun position adjusting mechanism (7) based on a difference between the outer margin width (S3) calculated by the outer margin width calculating means and a preset outer margin target width. And further,
The gluing device for the joint margin of the corrugated cardboard box according to claim 1.

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