JP2015069519A - Work table - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a work table for suitably performing cell production work.SOLUTION: A work table 1 has: work benches 10 and 10a; a monitor 11; a picking tray 12; a tray 13; a buzzer 14; a lamp 15; a PC 16; a PLC 17; and the like. On the picking tray 12, a document 20 is mounted, and a weight detection sensor 12a and a work detection sensor 12b are provided. On the tray 13, a sealed article 40 that encloses and seals the document 20 in an envelope 30 is mounted, and a weight detection sensor 13a is provided. The weight detection sensor 12a outputs a signal to the PLC 17 when a weight of the picking tray 12 decreases, and the work detection sensor 12b outputs a signal to the PLC 17 when detecting a take-out action of the document 20 by an operator. The weight detection sensor 13a outputs a signal to the PLC 17 when a weight of the tray 13 increases, and the PLC 17 performs work abnormality determination on the basis of the signal from each of the sensors.

Description

  The present invention relates to a work table for performing cell production work.

  Conventionally, various methods have been proposed for efficiently performing high-mix low-volume production. For example, Patent Document 1 describes a mechanism for performing high-mix low-volume production by line (conveyor) work without reducing work efficiency.

  In this method, the line is divided into an equipment line that requires large equipment and a manual work line, and a buffer is provided between these lines to finely adjust the quantity. By adjusting the number of equipment lines and manual work lines according to the product type, the line balance becomes uniform and efficient production becomes possible.

JP 2011-70407 A

  However, in the line work as described above, the number of workers tends to increase in order to make the line work function. Even if an operator hangs a plurality of processes, the movement distance of the worker increases depending on the length of the line, and the work efficiency is lowered. In addition, if there is no progress management system for the entire line and each process, there is also a problem that it is difficult to manage the scheduled work end time.

  One method for solving this problem is to increase production work (cell production work) performed independently by an operator and to improve the efficiency of such cell production work. However, in the current work environment for cell production work, work efficiency is not necessarily sufficient because human error is likely to occur, and a work environment that improves work efficiency is required.

  The present invention has been made in view of the above problems, and an object thereof is to provide a work table for suitably performing cell production work.

  A first invention for solving the above-described problem is to output a signal to the control device upon detecting a control device, a member placement portion on which a member related to work is placed, and a decrease in members on the member placement portion. A first sensor that outputs, a second sensor that outputs a signal to the control device upon detecting the removal action of the member on the member placement portion, and a finished product placement portion on which a finished product including the member is placed And a third sensor that outputs a signal to the control device when an increase in the number of finished products on the finished product placement unit is detected, and the control device performs the work based on a signal from each sensor. It is a work table characterized by performing an abnormality determination.

  By performing the cell production work using the work table of the present invention, unlike the line work, the number of persons required to make the work function can be adjusted in units of one person, and the movement of the worker is also small. In addition, work desks detect work abnormalities at any time as described above, so it is possible to prevent and manage human errors that tend to occur in cell production work, improve work efficiency, and perform cell production. It is possible to reduce the management load. In addition, quality can be guaranteed by detecting and managing abnormalities.

It is preferable that the control device counts the number of the finished products based on a signal from the third sensor.
As a result, it is possible to manage the progress of the work, and by grasping the progress status such as the number of production and the scheduled end time of the work, it is possible to take measures such as turning a worker who is slow to work to another process.

Moreover, it is desirable to provide a display device for displaying the number of the finished products. Further, it is desirable that work contents are displayed on the display device.
Thereby, the present progress can be easily grasped by the worker or the administrator. Further, the work content can be displayed on the display device, so that the work can be performed accurately.

The first sensor and the third sensor preferably detect a decrease in the weight of the member mounting portion and an increase in the weight of the finished product mounting portion, respectively.
Thereby, increase / decrease in a member or a finished product can be detected with a simple configuration.

The work table preferably includes a work table on which the member placement unit is disposed and a work table on which the finished product placement unit is disposed, and each work table is provided with a wheel.
As a result, the members can be exchanged together with the workbench, which leads to an improvement in work efficiency and can easily cope with a layout change of the work environment.

The control device preferably determines that the operation is normal when the signals from the first sensor and the second sensor and the signal from the third sensor are alternately obtained.
Thereby, the determination based on the signal from each sensor can be suitably performed according to the work.

It is desirable to provide an alarm device that issues an alarm when the control device determines that the operation is abnormal.
As a result, the operator or the like is notified that an abnormality has occurred in the work, and the worker or the like can take appropriate measures.

Preferably, the member is a document enclosed in an envelope, and the finished product is an envelope enclosing the document.
Since such enclosing and sealing work is often a so-called multi-product small-quantity production, it is particularly effective to increase the efficiency of the cell production work by applying the work table of the present invention.

  According to the present invention, it is possible to provide a work table for suitably performing cell production work.

Diagram showing work table 1 The figure which shows the control system of the work table 1 The figure which shows replacement | exchange of the work bench | platform 10a The figure which shows the display of the monitor 11 Flow chart showing work procedure Diagram showing work table 1a

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

[First Embodiment]
First, a work table according to a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a diagram showing a work table 1, and FIG. 2 is a block diagram showing a control system of the work table 1.

  The work table 1 shown in FIG. 1 is used when enclosing and sealing work is performed in cell production work. In the enclosing and sealing operation, the document 20 which is a member related to the operation is enclosed in an envelope 30 by a predetermined number (for example, one), and the flap 30a is folded and sealed to produce a sealed product 40 which is a finished product.

  The work table 1 includes work tables 10 and 10a, a monitor 11, a picking tray 12 (member placing portion), a tray 13 (finished product placing portion), a buzzer 14, a lamp 15, a PC 16, a PLC 17, and the like.

  The work tables 10 and 10a are work desks having a rectangular top surface. The work tables 10 and 10a are arranged adjacent to each other and are fixed to each other by a detachable binding tool 103. A tray 13 and a picking tray 12 are arranged on the top surfaces of the work tables 10 and 10a, respectively. A bundle of envelopes 30 is also arranged on the work table 10.

  Documents 20 are stacked and placed on the picking tray 12. The picking tray 12 is provided with a weight detection sensor 12a (first sensor) and a work detection sensor 12b (second sensor).

  The weight detection sensor 12a is a sensor for detecting a decrease in the weight of the picking tray 12, and for example, a weight scale is used. A decrease in the number of documents 20 on the picking tray 12 can be detected by the weight detection sensor 12a.

  The work detection sensor 12b is a sensor for detecting the act of picking up the document 20 by the worker. In the present embodiment, a transmissive sensor is used as the work detection sensor 12b. The transmissive sensor normally receives the laser emitted from one sensor by the other sensor. However, when the operator reaches his / her hand on the picking tray 12 when taking out the document 20, the above laser is cut off by hand. The other sensor will not receive light. Thereby, it is possible to detect the act of taking out the document 20 by the operator.

  The tray 13 is used for stacking and placing sealing objects 40, and is provided with a weight detection sensor 13a (third sensor) attached thereto.

  The weight detection sensor 13a is a sensor for detecting an increase in the weight of the tray 13, and, for example, a weight scale is used as described above. The increase in the number of sealed items 40 on the tray 13 can be detected by the weight detection sensor 13a.

  The height of the work tables 10 and 10a is set to a height that facilitates standing work, for example, about 850 mm. Further, leg portions 101 extending downward are provided at the four corners of the work tables 10, 10 a, and wheels 102 are provided at the lower end portions of the leg portions 101.

  This facilitates the movement of the work tables 10 and 10a, and can easily cope with the layout change of the work environment. Further, for example, after a series of work is completed, the work table 10a is separated from the work table 10 and another work table 10a is newly adjacent to the work table 10 as shown in FIG. it can. In the present embodiment, when the operator replaces the work table 10a in this manner, the waiting time of the supplier of the document 20 is reduced. In addition, the waiting time for workers is eliminated. Since the workbench 10a can be easily replaced, there is no heavy burden on the operator.

Monitor 11, buzzer 14, lamp 15, PC16, PLC (Programmable)
The logic controller 17 is provided on the work table 10.

  The monitor 11 is a display device that displays work progress status, work content, and the like.

  The buzzer 14 and the lamp 15 are alarm devices for alarming work abnormalities with sound and light, respectively.

PC16 and PLC17 comprise the control apparatus in this invention.
The PC 16 manages the progress of work and occurrence of abnormalities, and is a general computer having a control unit and a storage unit. The PC 16 is connected to the monitor 11, and the display on the monitor 11 is changed as needed under the control of the PC 16.

  The PLC 17 is connected to each sensor, the buzzer 14, the lamp 15, and the PC 16 described above, and outputs a signal by a ladder program based on a signal acquired from each sensor. Based on the output signal, the progress of work by the PC 16 and the recording of the occurrence of an abnormality, an alarm by the buzzer 14 and the lamp 15 are performed.

  The above devices are connected by various cables (not shown) such as a USB cable, but wireless connection is also possible.

(2. Management of work progress)
In the work table 1 of the present embodiment, when the worker places the sealed article 40 on the tray 13, the weight detection sensor 13a of the tray 13 detects an increase in the weight of the tray 13 and sends a signal to the PLC 17, and accordingly, PLC 17 outputs a signal to PC 16.

  The PC 16 counts the number of sealed items 40 produced by this output signal, and records and updates the number of produced sealed items 40 and the like in the storage unit as progress status data indicating the progress status of the work. As the progress data, there are a production amount 51 and a production target value 52 per unit time, a total production 53 and a total production target 54 which will be described later.

  The PC 16 displays the above progress status data on the monitor 11. An example of display on the monitor 11 is shown in FIG. As shown in FIG. 4, the monitor 11 displays a production amount 51 and a production amount target value 52, a total production amount 53, and a total production amount target value 54 per unit time as progress status data.

  The production amount 51 per unit time is the number of sealed articles 40 produced per unit time such as one hour, and corresponds to the number of times the weight increase of the tray 13 is detected by the weight detection sensor 13a. The target value of the production quantity 51 per unit time is the production quantity target value 52, which is input to the PC 16 in advance.

  The total production amount 53 is a total value of the production amount 51 per unit time from the start of work. The target value of the total production quantity 53 is the total production quantity target value 54, which is input to the PC 16 in advance as described above.

  By displaying the progress of work as described above on the monitor 11, the worker and the manager can understand the progress of the work such as the number of production at a glance and can easily determine the scheduled work end time. When the production volume 51 per unit time and the total production volume 53 are less than the production volume target value 52 and the total production volume target value 54, respectively, by changing the display form such as the display color as the production delay, It may be easy to understand and urge attention.

  The monitor 11 also displays an explanation of the work content 55 using text and diagrams. By visually checking the work content 55, mistakes can be reduced and an accurate work can be realized.

(3. Work abnormality judgment)
In the work console 1 of the present embodiment, it is possible to perform work abnormality determination based on signals from the weight detection sensors 12a and 13a and the work detection sensor 12b.

  That is, according to a normal work procedure, the operator first takes out the document 20 on the picking tray 12, and at this time, the weight detection sensor 12a detects weight reduction and the work detection sensor 12b detects the removal action. Thereafter, the operator encloses the document 20 in the envelope 30 and seals it, and places the sealed object 40 on the tray 13, and at this time, the weight detection sensor 13a detects an increase in weight.

  Accordingly, the PLC 17 is normal when the signals from the weight detection sensor 12a and the work detection sensor 12b and the signal from the weight detection sensor 13a are obtained alternately, and otherwise the buzzer 14 and the lamp 15 are abnormal. An alarm signal can be output to the PC 16 to issue an alarm, or an abnormality signal can be output to the PC 16 to record the occurrence of an abnormality.

As an example of the above abnormality, for example,
1. When the signal from the weight detection sensor 12a or the work detection sensor 12b is continuous (for example, when the document 20 is taken out extra)
2. When the signal from the weight detection sensor 13a is continuous (for example, when the sealed object 40 is placed on the tray 13 and then the document 20 is taken out, and only the envelope 30 is placed on the tray 13 without enclosing and sealing)
3. When there is a signal from only one of the weight detection sensor 12a and the work detection sensor 12b (for example, when taking out the document 20 fails)
and so on.

However, it is not limited to this. For example, by setting a time limit for work and setting it in the PLC 17,
4). An abnormality can also be determined when there is a time interval exceeding the time limit between the signal from the weight detection sensor 12a or the work detection sensor 12b and the signal from the weight detection sensor 13a.

In addition, the weight increase / decrease width is output to the PLC 17 from the weight detection sensors 12a and 13a. In the PLC 17, the weight decrease width of the picking tray 12 when the document 20 is taken out from the picking tray 12 or the tray 13 is sealed. By setting a reference range for each increase in the weight of the tray 13 when the object 40 is placed,
5. When the weight decrease detected by the weight detection sensor 12a exceeds the reference range (for example, when extra documents 20 are taken out)
6). When the increase in weight detected by the weight detection sensor 13a exceeds the reference range (for example, when there is an extra document 20 in the envelope 30)
7). When the weight increase detected by the weight detection sensor 13a falls below the reference range (for example, when the document 20 in the envelope 30 is insufficient)
It can also be determined as abnormal.

  It is desirable that the abnormality determination timing by the PLC 17 is the timing at which the signal from the weight detection sensor 13a is acquired, so that it is easy to grasp what abnormality has occurred in the sealing operation of the sealed object 40. For example, the above 1. In this case, when the signal from the weight detection sensor 13a is acquired, if the signal from the weight detection sensor 12a or the work detection sensor 12b continues immediately before that, it is determined that there is an abnormality.

  However, the present invention is not limited to this. In the above case, when the signal from the weight detection sensor 12a or the work detection sensor 12b continues, it is determined that there is an abnormality. In this case, it is possible to determine that an abnormality has occurred when the time limit has elapsed since the signal from the weight detection sensor 12a or the work detection sensor 12b has been acquired.

(4. Work procedure using work table 1)
Next, a work procedure using the work table 1 will be described with reference to FIG. FIG. 5 is a flowchart showing a work procedure, and each step in the figure is a process executed by the PLC 17.

  As described above, in the present embodiment, the document 20 on the picking tray 12 is first taken out by the worker. At this time, the weight detection sensor 12a detects the weight reduction, and the work detection sensor 12b detects the worker's take-off action. To do. Thereafter, the operator encloses the document 20 in the envelope 30, folds and seals the flap 30a, places the sealed object 40 on the tray 13, and at this time, the weight detection sensor 13a detects an increase in weight. Each sensor outputs a signal to the PLC 17 when these sensors are detected. The PLC 17 acquires each signal (S1).

  As described above, the PLC 17 determines the abnormality of the work (S2). If there is an abnormality (S3; YES), the PLC 17 outputs an abnormality signal indicating that to the PC 16 and outputs an alarm signal to the buzzer 14 or Output to the lamp 15 (S4). The PC 16 records the timing of occurrence of an abnormality as data such as the number of sealed items 40 in accordance with the abnormality signal so that it can be confirmed later. Further, the buzzer 14 and the lamp 15 issue a warning by sound or light according to the warning signal and notify the operator that an abnormality has occurred. The operator performs necessary actions as appropriate, then performs the work again, and the process returns to S1.

  If these abnormality signals and alarm signals are different for each type of abnormality described above, the type of abnormality is recorded on the PC 16 according to each signal, or the abnormality is different for each type of abnormality by the buzzer 14 or the lamp 15. It is also possible to give an alarm by sound or light.

  When the work is normal (S3; NO), the PLC 17 outputs a count signal for increasing the number of sealed items 40 produced by 1 to the PC 16 in accordance with a signal from the weight detection sensor 13a of the tray 13 (S5). In accordance with this count signal, the PC 16 updates the number of production quantities 51 and total production quantities 53 per unit time of the progress status data by one. The display of these values on the monitor 11 is also updated.

  The PLC 17 determines whether the output number of the count signal has reached a predetermined number of predetermined intervals as a count number (S6), and performs the processing of S1 to S6 until the predetermined number is reached (S7; NO). repeat. If the predetermined number is reached (S7; YES), an end signal indicating that is output to the buzzer 14 and the lamp 15 (S8).

  When the buzzer 14 and the lamp 15 receive the end signal, the buzzer 14 and the lamp 15 issue an alarm with a sound or light different from the previous one to notify the worker that the work is finished. In response to this, the worker finishes the work, replaces the document 20 together with the work table 10a as necessary, and starts a new work.

  By performing cell production work using the work console 1 of the present embodiment described above, unlike the line work as described above, the number of people required to make the work function can be adjusted in units of one person. There is also little movement of workers. In addition, since the work console 1 detects abnormalities as described above, it can prevent and manage human errors that are likely to occur in cell production work, improve work efficiency, and perform cell production. Management load can be reduced. In addition, quality can be guaranteed by detecting and managing abnormalities.

  Further, since the PLC 17 counts the number of sealed items 40 based on the signal from the weight detection sensor 13a, it is possible to manage the progress of the work, and by grasping the progress status such as the number of production and the scheduled end time of the work, It is possible to take measures such as sending a slow worker to another process.

  Furthermore, since the work table 1 displays the production number of the sealed items 40 and the work content 55 on the monitor 11, the current progress can be easily grasped by the worker and the administrator, and the work content 55 can be confirmed. And work can be done accurately.

  In the present embodiment, the weight detection sensors 12a and 13a detect the decrease in the weight of the picking tray 12 and the increase in the weight of the tray 13, respectively. However, the present invention is not limited to this. For example, the increase / decrease of the document 20 or the sealed object 40 can also be detected by measuring the height of the upper surface of the document 20 or the sealed object 40 with a laser distance meter, for example. However, in the case of this embodiment, there exists an advantage which can detect the increase / decrease in the document 20 or the sealing material 40 with a simple structure.

  In addition, although the transmission type sensor is used as the work detection sensor 12b, a reflection type sensor can also be used. In the case of a reflective sensor, when an operator reaches his / her hand on the picking tray 12 when taking out the document 20, the laser emitted from the sensor is reflected by the hand and received by the sensor. Normally, this laser cannot be received by the sensor, so that the operator's take-off action can be detected by receiving the laser.

  Further, in the present embodiment, since the wheels 102 are provided on the work tables 10 and 10a, the document 20 can be exchanged together with the work table 10 to improve work efficiency, and the work environment layout can be easily changed.

  In addition, when the PLC 17 alternately acquires the signals from the weight detection sensor 12a and the work detection sensor 12b and the signal from the weight detection sensor 13a, the PLC 17 determines that the work is normal, and therefore the work based on the signal from each sensor. This determination can be preferably made according to the work content.

  In the present embodiment, for example, a laser distance meter or the like for measuring the height of the flap 30a in the sealed object 40 is provided above the tray 13, so that the flap 30a is properly closed (a position where the flap is low). It is also possible to determine whether or not

  Moreover, since the work table 1 includes alarm devices such as the buzzer 14 and the lamp 15, the worker or the like can be informed that an abnormality has occurred in the work, and the worker or the like can take appropriate measures.

  Further, in the present embodiment, the work table 1 has been described by taking the case of performing the sealing operation as an example, but the scope of application of the work table 1 is not limited to this, and members related to the work are taken out from the picking tray 12. Any work that places a finished product including the member on the tray 13 is applicable. Further, instead of the picking tray 12 or the tray 13, another container or table can be used. As the above-mentioned work, for example, an assembling work for paper container products and the like can be mentioned. However, since the enclosing and sealing work as in this embodiment is often a so-called multi-product small-quantity production, it is particularly effective to apply the work table 1 to increase the efficiency of the cell production work.

[Second Embodiment]
In the first embodiment, an example in which the document 20 is taken out and sealed from a bundle of single documents 20 has been shown. However, as an operation, a plurality of types of documents 20 may be sealed in the envelope 30. Such a case will be described in the second embodiment. The second embodiment will mainly describe differences from the first embodiment, and description of similar points will be omitted.

  FIG. 6 is a diagram showing a work table 1a according to the second embodiment. As shown in the figure, in the work table 1 a, a plurality of work tables 10 a each having a bundle of different types of documents 20 placed on the picking tray 12 are arranged continuously with the work table 10. An operator takes out the document 20 from the picking tray 12 of each work table 10 a, seals the document 20 in an envelope 30, and places the sealed object 40 on the tray 13.

  The processing procedure in the PLC 17 in this case is basically the same as that described in FIG. However, the abnormality determination in S2 is normal when signals from all the weight detection sensors 12a and work detection sensors 12b and signals from the weight detection sensors 13a are alternately repeated.

In other words, when the signal from the weight detection sensor 13a is acquired, immediately before that, 8. When signals from the weight detection sensors 12a or work detection sensors 12b of all the picking trays 12 are not acquired (when the documents 20 of any picking tray 12 are not taken out)
Becomes abnormal.

  In the case as shown in FIG. 6, the type of document 20 to be enclosed may be changed for each sealed object 40. That is, this is a case where a different document 20 is sent for each destination of the sealed object 40.

  In this case, for example, the first sealed item 40 holds data in which the document A, the document C, the document D, etc., and the ordinal number (count number) of the sealed item 40 and the type of the document 20 to be extracted are associated with each other. Keep it.

  During the sealing operation, the type of the document 20 corresponding to the next sealed item 40 is displayed on the monitor 11 according to the number of the sealed items 40 produced, or the picking tray 12 corresponding to the type of document 20 is supported. Work assistance is performed by turning on a lamp (not shown).

  The processing procedure in the PLC 17 in this case is basically the same as that described with reference to FIG. However, in the abnormality determination of S2, the PLC 17 refers to the association data described above, and all necessary signals from the weight detection sensor 12a and work detection sensor 12b and signals from the weight detection sensor 13a are alternately repeated. If normal.

That is, for example, when a signal from the weight detection sensor 13a is acquired, immediately before that, 9. When there is a signal from the weight detection sensor 12a or the work detection sensor 12b of the picking tray 12 of the unnecessary document 20, such as when the unnecessary document 20 is taken out
10. When there is no signal from the weight detection sensor 12a or the work detection sensor 12b of the picking tray 12 of the necessary document 20 (for example, when the necessary document 20 is not taken out)
Becomes abnormal.

  In addition to the types of documents 20 to be extracted, it is possible to specify the order of extraction in the above association data. In this case, the type and order of the documents 20 to be extracted are displayed on the monitor 11 or each picking is performed. A lamp (not shown) corresponding to the tray 12 is turned on in order according to the order of the documents 20 to be taken out, for example, to assist the work.

Moreover, in the abnormality determination of S2,
11. When the signals from the weight detection sensor 12a or the work detection sensor 12b of the picking tray 12 are not acquired in the order corresponding to the specified order of taking out the documents 20 (such as when the order of taking out the documents 20 is different).
Can also be determined as abnormal.

  Also in the second embodiment described above, the same effect as in the first embodiment can be obtained. Further, there is an advantage that it can be suitably applied to various enclosing and sealing operations for enclosing and sealing a plurality of types of documents 20.

  The preferred embodiments of the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to such examples. It will be apparent to those skilled in the art that various changes or modifications can be conceived within the scope of the technical idea disclosed in the present application, and these are naturally within the technical scope of the present invention. Understood.

1; work table 10, 10a; work table 11; monitor 12; picking tray 13; tray 14; buzzer 15;
17; PLC
20; Document 30; Envelope 40;

Claims (9)

A control device;
A member placement unit for placing a member related to the operation;
A first sensor that outputs a signal to the control device upon detecting a decrease in the number of members on the member mounting portion;
A second sensor that outputs a signal to the control device upon detecting the removal of the member on the member mounting portion;
A finished product placement unit for placing a finished product of the work including the member;
A third sensor that outputs a signal to the control device upon detecting an increase in the number of finished products on the finished product placement section;
Comprising
The work console characterized in that the control device performs abnormality determination of the work based on a signal from each sensor.   2. The work table according to claim 1, wherein the control device counts the number of the finished products based on a signal from the third sensor.   The work table according to claim 2, further comprising a display device that displays the number of the finished products.   The work table according to claim 3, wherein work contents are displayed on the display device.   5. The first sensor and the third sensor respectively detect a decrease in the weight of the member placement portion and an increase in the weight of the finished product placement portion. A work table as described in any of the above. The work table includes a work table on which the member placement unit is disposed, and a work table on which the finished product placement unit is disposed.
The work table according to any one of claims 1 to 5, wherein each workbench is provided with a wheel. The controller is
7. The method according to claim 1, wherein when the signals from the first sensor and the second sensor and the signal from the third sensor are alternately acquired, it is determined that the operation is normal. The work desk described in any one.   8. The work console according to claim 1, further comprising an alarm device that issues an alarm when the control device determines that the operation is abnormal. The member is a document enclosed in an envelope,
9. The work table according to claim 1, wherein the finished product is an envelope enclosing the document.

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