JP2691408B2 - Sheet separating and delivering method, sheet separating and delivering apparatus, and sheet laminated body - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for separating and delivering laminated sheets one by one, a sheet separating and delivering apparatus used for carrying out the method, and a sheet stacking used therefor. More particularly, the present invention relates to a sheet separating and delivering method, a sheet separating and delivering apparatus, and a sheet laminated body which are suitable for separating and delivering sheets which are very thin and are easily double-fed due to their materials such as stencil printing base paper.

2. Description of the Related Art Problems to be Solved by the Prior Art and Invention The sheet separating and feeding used as a sheet feeding device of a copying machine, a printing machine or the like is generally made of rubber that is pushed up to the uppermost one of vertically stacked sheets. The feed roller is rotated to separate the uppermost sheet and the second sheet by the sheet separating member or the corner separator, and the uppermost sheet is fed one by one.

In the sheet separating apparatus as described above, if the sheets to be handled are ordinary copy sheets or plain sheets as printing sheets, a plurality of sheets are not frequently fed simultaneously, so-called double feeding does not occur. Paper that can withstand practical use, but is handled as thin as a single-cut stencil sheet without a backing paper, made of a special material, and that easily sticks to each other due to static electricity, etc. The separated sheets are not separated well, and double feeding occurs frequently, which is not practical.

In view of the above-mentioned problems, the sheets are held in a suspending manner in the storage portion, and the pressing force acting on the sheets by their own weight during stacking is reduced to prevent the sheets from sticking to each other by the pressing force, It has been considered that the separation and delivery of the sheets should be performed well, and this is shown, for example, in Japanese Utility Model Laid-Open No. 60-195838.

The sheet separation structure as described above reduces the frequency of double feeding as compared with the case where sheets are stacked vertically in the storage portion, but there is still a possibility that adjacent sheets may stick to each other. If the sheets stick together, double feeding will still occur, and it is impossible to eliminate double feeding altogether.

The present invention provides a sheet separating / delivering method capable of eliminating the double feeding of sheets and always sending out the sheets one by one, and a sheet separating / delivering device and a sheet laminated body used for carrying out the method. The purpose is to do.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention According to the present invention, the above-described object is to provide a sheet separating / feeding device having four sides forming a rectangular contour, and a pair of the four sides facing each other as side edges, A pair of sheets as the leading edge and the trailing edge is used as a method of sending only the uppermost sheet in the direction from the trailing edge to the leading edge along the sheet surface at a time, and A first cutout portion having a notch portion that is close to the rear edge and is open to the rear edge at a position, and an engaging hole that is close to the rear edge but is not open at the rear edge at a second position along the rear edge. And a pair of side edges, a front edge and a rear edge corresponding to a pair of side edges, a front edge and a rear edge of the first sheet, respectively, which have the same rectangular contour as the first sheet. , The first sheet corresponding to the first position of the first sheet has a reduced number of notches in the first sheet. Also has an engaging hole having an opening area corresponding to a part thereof, and an opening area corresponding to the engaging hole of the first sheet at a second position corresponding to the second position of the first sheet. And a second sheet having a notch opening at the trailing edge and an alternate laminate, and when the uppermost layer of the sheet laminate is the first sheet, the first position of each sheet In the first state in which the first engaging pin is penetrated from the lowermost layer to the uppermost layer of the sheet laminated body in the corresponding opening area of the notch or the engaging hole of each sheet, the uppermost layer of the sheet laminated body is When the sheet is the second sheet, at the second position of each sheet, a second engagement pin is provided from the lowermost layer to the uppermost layer of the sheet laminate in the corresponding opening area of the notch or the engaging hole of each sheet. By the method characterized by alternately realizing the penetrated second state, The separating / delivering device has four sides having a rectangular contour, one pair of the four sides facing each other is a side edge, the other pair is a front edge and a rear edge, and the rear side is located at a first position along the rear edge. A first sheet having a notch portion that is close to the edge and that opens to the rear edge, and that has an engaging hole that is close to the rear edge but does not open to the rear edge at a second position along the rear edge, Forming the same rectangular contour as the first sheet, and having a pair of side edges, a front edge and a rear edge respectively corresponding to the pair of side edges, a front edge and a rear edge of the first sheet, A first position corresponding to the first position of the sheet of the first sheet has an engagement hole having an opening region corresponding to at least a part of the cutout portion of the first sheet, A notch portion having an opening region corresponding to the engaging hole of the first sheet and opening at the rear edge is provided at a second position corresponding to the second position. A sheet for supporting the sheet laminate, which is a device for delivering only the uppermost layer sheet in the direction from the trailing edge to the leading edge along the surface of the sheet at a time by the alternate laminate with the second sheet. A mounting table, sheet driving means for driving the uppermost sheet of the sheet stack mounted on the sheet mounting table in the direction from the trailing edge to the leading edge along the surface of the sheet, and on the sheet mounting table Each sheet of the sheet laminated body is selectively penetrated from the lowermost layer to the uppermost layer of the sheet laminated body at the first position through the notch of each sheet or the corresponding opening area of the engaging hole. And a first engagement pin that can be formed, and each sheet of the sheet stack mounted on the sheet mounting table is passed through the corresponding opening area of the notch or the engagement hole of each sheet at the second position. Selectively penetrates from the bottom layer to the top layer of the sheet stack When the second engaging pin, the first engaging pin and the second engaging pin are pushed up to a position where one of them penetrates the uppermost sheet of the sheet laminated body, the other becomes the uppermost layer of the sheet laminated body. A sheet stack having four sides forming a rectangular contour, and a pair of the four sides facing each other. As a side edge, the other pair is a front edge and a rear edge, and at a first position along the rear edge, having a notch portion that is close to the rear edge and opens to the rear edge, and at a second position along the rear edge. A first sheet having an engaging hole that is close to the trailing edge but does not open to the trailing edge, has the same rectangular contour as the first sheet, and has a pair of side edges of the first sheet, A pair of side edges respectively corresponding to the leading edge and the trailing edge, a leading edge and a trailing edge, A first position corresponding to the first position of the sheet of the first sheet has an engagement hole having an opening region corresponding to at least a part of the cutout portion of the first sheet, A second sheet having an opening region corresponding to the engaging hole of the first sheet at a second position corresponding to the second position and having a notch opening at the trailing edge, This is achieved by a laminate.

Further, in the sheet laminate as described above according to the present invention, an identification mark for identifying both of the first sheet and the second sheet may be provided.

In the sheet separating method and apparatus according to the present invention,
In the stack of sheets, except for the uppermost or lowermost one sheet to be fed, the feeding is forcibly prevented by the locking member, so that even if the adjacent sheets stick to each other, It is possible to reliably avoid the occurrence of double feeding in which two sheets are fed at the same time when two sheets are fed simultaneously when one sheet is fed, and there is no occurrence of double feeding.

In particular, according to the present invention, when the uppermost sheet of the sheet stack is delivered along the face of the sheet in a direction from the trailing edge of the sheet to the leading edge, the lowermost sheet next to the uppermost layer is The movement of the sheet following the seat is securely locked at the trailing edge portion by the engagement of the engagement hole and the engagement pin provided therein without relying on friction, so that the uppermost layer No matter which part of the sheet the sheet and the sheet of the next lower layer are stuck together, the sheet of the next lower layer of the uppermost layer is always held in the stretched state.

Embodiments The present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 shows one embodiment of a plate-making stencil printing machine provided with a sheet separating / feeding device according to the present invention in a stencil sheet supply section. In FIG. 1, reference numeral 10 denotes a cylindrical plate cylinder. The cylindrical plate cylinder 10 is composed of a cylindrical body having a porous structure, and a clamping means 12 for locking one end of the stencil sheet S on the outer peripheral surface thereof. The printing ink is supplied from the ink supply device 14 provided inside and is rotated in the counterclockwise direction in the figure by an electric motor (not shown). A press roller 16 is provided below the cylindrical plate cylinder 10, and the press roller 16 is selectively moved toward the outer peripheral surface of the cylindrical plate cylinder 10 by a cam mechanism 18 in synchronization with the rotation of the cylindrical plate cylinder 10. It is designed to be pressed against.

A sheet feeding device 20 is provided on one side of the cylindrical plate cylinder 10 with respect to the pre-loss roller 16. The sheet feeding device 20 has a sheet feeding table 22 on which a plurality of plain sheets of printing paper W are stacked and placed. The printing paper W stacked and placed on the paper feed table 22 is taken out while being separated one by one from the uppermost one by the feed roller 24 and the paper separating pad 26, and is cylindrical by the registration roller 28 at a predetermined time. It is sent between the plate cylinder 10 and the press roller 16, and when passing between these, the printing ink that has passed through the perforated portion of the stencil sheet attached to the outer peripheral surface of the cylindrical plate cylinder 10 is transferred, and this printing It is designed to carry a printed image with ink. The printed printing paper is peeled off from the cylindrical plate cylinder 10 by the separating claw 30 and is discharged onto the paper ejection tray.
32 will be stacked on top.

Further, in FIG. 1, reference numeral 40 denotes a base paper feeding device equipped with the sheet separating and feeding device according to the present invention.
The reference numeral 40 has a base paper mounting table 42 on which a plurality of single-cut stencil base papers S are stacked in the vertical direction. The stencil sheet S placed on the stencil sheet mounting table 42 is taken out one by one by the rotation of the feed roller 44 in a manner described later, reaches the conveying roller 48 while being guided by the guide member 46, and is further conveyed by the conveying roller 48. It is fed between the platen roller 50 and the thermal head 52, at which time the thermal head 52 performs heat-sensitive plate making, and the conveying roller 54 clamps the cylindrical plate cylinder 10
It will be sent to 12. The plate-making stencil sheet S which has been plate-made has one end locked to the outer peripheral surface of the cylindrical plate cylinder 10 by the clamp means 12, and is wound around the outer peripheral surface of the cylindrical plate cylinder 10 as the cylindrical plate cylinder 10 rotates. ing. On the side opposite to the plate making section composed of the raw paper supply device 40 and the thermal head 52 and the like, a used plate stencil 56 for stripping the used stencil sheet from the cylindrical plate cylinder 10 and the stripped used stencil sheet A plate discharge winding roller 60 for feeding the sheet into the plate discharge box 58 is provided.

Next, one embodiment in which the sheet separating and feeding apparatus according to the present invention is incorporated in the base paper feeding apparatus of the plate making stencil printing machine will be described with reference to FIGS. 2 and 3. Base paper stand 42
Is provided with a stencil sheet stack B on its upper surface, and the compression roller spring 43 (first
(Refer to the figure), it is urged upward in the figure. As a result, the laminated material B placed on the base paper mounting table 42 comes into contact with the feed roller 44 by the stencil paper at the uppermost position, and the delivery end side is pressed against the feed roller 44.

A swing lever 72 supported by a pin 70 so as to be pivotable from a frame 41 (see FIG. 1) by a pin 70 is provided below the end of the base paper placing table 42 on the side opposite to the end for feeding the base paper. A first engagement pin 74 and a second engagement pin 76 are pivotally connected to both ends of the swing lever 72. The first and second engagement pins 74 and 76 are respectively erected from the ends of the swing lever 72, and the base paper mounting table 42 is provided by a length corresponding to the lever length of the swing lever 72.
Positioned apart from each other in the width direction of the upper stencil sheet, the first engaging pin 74 penetrates the opening 78 formed in the raw sheet mounting table 42 to align with it and projects onto the raw sheet mounting table 42, Further, the second engagement pin 76 can penetrate the opening 80 provided in the base paper mounting table 42 to be aligned therewith and project onto the base paper mounting table 42. Since the first engagement pin 74 and the second engagement pin 76 are attached to both ends of the swing lever 72 pivotally supported by the pin 70, the pin 70 of the swing lever 72 is When the swing lever 72 moves up and down in a mutually contradictory relationship due to the swing around the center and the swing lever 72 rotates clockwise in FIG. 2, the first engaging pin 74 rises from the state shown in the drawing, The second engagement pin 76 is lowered from the state shown in the figure. On the contrary, when the swing lever 72 is rotated counterclockwise in FIG. 2, the first engaging pin 74 is lowered from the illustrated state, and the second engaging pin 76 is moved from the illustrated state. To rise.

The swing lever 72 is a connecting pin 77 with the second engaging pin 76.
The tension coil spring 82 provided between the spring fixing member 39 attached to the frame 41 and the spring fixing member 39 is always biased clockwise in FIG. One end of another tension coil spring 84 is locked to the connecting pin 75 of the swing lever 72 with the first engagement pin 74.
Is connected to the plunger 90 of the solenoid device 88 via the reel 86 at the other end.

When the solenoid device 88 is energized, the plunger 90 retracts to drive the engagement pin 74 downward via the tension coil spring 84 in the drawing. As a result, when the solenoid device 88 is energized, the rocking lever 72 rotates counterclockwise in the figure against the spring force of the tension coil spring 82, and the second engagement pin 76 moves to the first position. One engagement pin
74, and when the solenoid device 88 is not energized, the spring force of the tension coil spring 82 causes the swing lever 72 to rotate in the clockwise direction in the figure, so that the first engaging pin 74 rises above the second engagement pin 76.

As shown in FIG. 3, the laminated body B of the anti-paper base paper used in the sheet separating / delivering device having the above-described structure extends to the first position of the trailing edge in the direction opposite to the feeding direction. A first stencil sheet S ₁ having a notch portion C ₁ provided therein and having an engaging hole H ₁ at a second position different from the first position in the width direction; An edge has an engaging hole H ₂ at the same position as the first position and a notch C ₂ provided at the same position as the second position and extending in a direction opposite to the delivery direction. second and stencil sheet S ₂ of are alternately stacked, engaging hole of H ₂ notch C ₁ and the second stencil sheet S ₂ of the first stencil sheet S ₁ as viewed in laminate B
It forms a continuous opening through the stacking direction overlap each other, also seen in the laminate B a first engaging hole H ₁ of the stencil sheet S ₁ and the notch C ₂ of the second stencil sheet S ₂ and Overlap each other and penetrate in the stacking direction to form a continuous opening. Distance and second width direction of the distance between the notch C ₂ and the engaging hole of H ₂ stencil sheet S ₂ of the first notch C ₁ and the engaging hole H ₁ of the stencil sheet S ₁ is the The distance between the first engagement pin 74 and the second engagement pin 76 is equal to the distance between the first engagement pin 74 and the second engagement pin 76, so that the continuous state formed by the notch C ₁ and the engagement hole H ₂ is placed on the base paper placing table 42. The first engaging pin 74 is engaged through, and the second engagement is made in the continuous opening formed by the engaging hole H ₁ and the notch C _{2 in} the mounting state on the base paper mounting table 42. The pin 76 is adapted to penetrate therethrough.

Both the first stencil sheet S ₁ and the second stencil sheet S ₂ have a reinforcing paper R at the front edge thereof, and the reinforcing paper R has the same pattern as each other in the engaging holes for plate making. P is provided.

Next, the operation of the sheet separating and feeding device having the above-mentioned structure will be described. As shown in FIG. 2, when the first stencil sheet S ₁ is at the top of the stack B, the energization of the solenoid device 88 is stopped, which causes the first engagement pin 74 to move upward. This penetrates through a continuous opening in the stacking direction due to the overlapping of the notch C ₁ and the engaging hole H ₂ through the opening 78, and the upper end of the first stencil sheet S ₁ forming the uppermost layer. The second engaging pin 76 is fitted in the notch C ₁ , and the second engaging pin 76 is in a lowered state, and the upper end thereof is at least disengaged from the engaging hole H _{1 of the} uppermost stencil sheet S ₁ .
In this state, when the feeding roller 44 is driven to rotate in the clockwise direction as seen in FIG. 2, the uppermost first stencil sheet S ₁ is in the direction indicated by arrow A in the figure due to frictional force. Will be sent to. Although at this time the cut-out portion C ₁ is engaged with the first engagement pin 74, the cutout portion C ₁ is that provided extending in the opposite direction to the delivery direction of the hole plate sheet Therefore, the first stencil sheet S ₁ can be sent out without being disturbed by the first engagement pin 74 without being disturbed. Stencil sheet handsome in from the first stencil sheet S ₁ at this time under one is a second stencil sheet S _1, the second stencil sheet S ₂ is first in the engaging hole H ₂ Since it is engaged with the first engagement pin 74, the engagement with the first engagement pin 74 is exerted even if the first stencil sheet S ₁ on it is given a moving force in the delivery direction accompanying the delivery. Then, the delivery movement is forcibly prevented, and the delivery movement is surely prevented. As a result, even if the uppermost first stencil sheet S and the second stencil sheet S ₂ which is one sheet below the uppermost stencil sheet S are attached to each other, they are separated from each other when the first stencil sheet S ₁ is sent out, First stencil paper S ₁
Only will be sent.

When the first stencil sheet S _{1 at} the uppermost position is delivered, the second stencil sheet S ₂ is next positioned at the uppermost position of the stack B, and at this time, the solenoid device 88 is energized. Done. As a result, the first engagement pin 74 has the notch C ₁ and the engagement hole H ₂
Extracted from the continuous opening in the stacking direction due to the overlap with
On the other hand, the second engagement pin 76 pierces the continuous opening in the stacking direction due to the overlapping of the engagement hole H ₁ and the cutout portion C ₂ and makes a penetrating engagement. Again feed rollers 44 for delivery of the second stencil sheet S ₂ in this state is rotated in the clockwise direction in the figure, at the second stencil sheet S ₂ is the arrow A by the frictional force It will start to move in the indicated direction. At this time, since the second stencil sheet S ₂ is engaged with the second engaging pin 76 at the notch C ₂ extending in the direction opposite to the feeding direction of the stencil sheet, the feeding movement is prevented. It is not blocked by the second engagement pin 76, while the first stencil sheet S ₁ located one sheet below the second engagement pin 76 engages with the second engagement pin 76 in the engagement hole H ₁ . As a result, the first stencil sheet S ₁ is forcibly prevented from being delivered by the second engagement pin 76, and is delivered even if a delivery moving force is applied from the second stencil sheet S ₂ by sticking. It does not move, and only the uppermost second stencil sheet S ₂ is delivered.

As described above, the first sheet S ₁ at the top of the stack B is
Alternatively, each time the second sheet S ₂ is delivered, the first engagement pin
The 74 and the second engaging pin 76 are alternately inserted into the continuous opening formed by the cutout portion C ₁ and the engagement H ₂ or the continuous opening formed by the engagement hole H ₁ and the cutout portion C _{2 so as} to be surely inserted. The delivery of the first stencil sheet S ₁ or the second stencil sheet S _{2 in} the _second sheet is forcibly prevented, and thus the first stencil sheet S ₁ which is always at the top is Alternatively, only the second stencil sheet S ₂ is surely delivered, and the double feeding of the stencil sheet is surely avoided.

Further, the first stencil sheet S ₁ is provided with an identification mark M for distinguishing it from the second stencil sheet S by an appropriate means such as printing.

Further, the sheet separating / feeding device is provided with a photoelectric reading device 110 including a combination of a light emitting element 106 for photoelectrically reading the identification mark M and a light receiving element 108. The photoelectric reading device 110 outputs a control signal to a control device (not shown) of the solenoid device 102 in response to the reading of the identification mark M, and controls energization of the solenoid 102.

In the above, the present invention has been described in detail with respect to specific embodiments, but the present invention is not limited to these, and it is apparent that various embodiments are possible within the scope of the present invention. It will be obvious to the trader.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram of an embodiment of a plate-making stencil printing machine in which a sheet separating / feeding device according to the present invention is incorporated in a base paper feeding device, and FIG. 2 is a sheet-making stencil printing device according to the present invention. FIG. 3 is a schematic perspective view showing one embodiment applied as a stencil sheet separating and feeding apparatus, and FIG. 3 is one embodiment of a laminated body of stencil sheet used in the stencil sheet separating and feeding apparatus of the embodiment shown in FIG. It is a schematic perspective view showing. 10 …… Cylindrical plate cylinder, 12 …… Clamping means, 14 …… Ink supply device, 16 …… Press roller, 18 …… Cam mechanism, 20 …… Paper feeder, 22 …… Paper feeder, 24 …… Feed roller, 26 …… Paper separating pad, 28 …… Ristist roller, 30 …… Separating claw, 32 …… Paper tray, 39 …… Spring stop member, 40 …… Base paper feeder, 41 ……
Frame, 42 …… Base paper mounting table, 43 …… Compression coil spring, 44
...... Feed roller, 46 …… Guide member, 48 …… Transport roller, 5
0 …… Platen roller, 52 …… Thermal head, 54 …… Conveyor roller, 56 …… Paper ejection claw, 58 …… Plate ejection box, 60 …… Base paper winding roller, 70 …… Pin, 72 …… Swing lever , 74 ……
1st engaging pin, 75 ...... connecting pin, 76 ...... second engaging pin, 77 ... connecting pin, 78,80 ... opening, 82 ... tensile coil spring, 84 ... tensile coil spring, 86 …… reel, 88 ……
Solenoid device, 90 …… Blanger, 106 …… Light emitting device, 10
8 ... Photodetector, 110 ... Photoelectric reader, B ... Laminated stencil paper, Laminated printing paper ... W, S ₁ ...... First stencil base paper, S ₂ ...... Second stencil Base paper, C ₁ , C ₂ ... Notches, H ₁ , H ₂
…… Engagement hole, M …… Identification mark

Claims (3)

(57) [Claims] 1. A sheet having the four sides of a rectangular contour, one pair of the four sides facing each other being a side edge, and the other pair being a leading edge and a trailing edge only the uppermost sheet at a time. Is provided in a direction from the trailing edge to the leading edge along the surface of the sheet, and the first position along the trailing edge has a notch portion adjacent to the trailing edge and opening to the trailing edge. A first sheet having an engaging hole that is close to the trailing edge but not open to the trailing edge at a second position along the line, and has the same rectangular contour as the first sheet, and the first sheet A pair of side edges, a front edge, a pair of side edges respectively corresponding to the rear edge, a front edge, a rear edge, the first position corresponding to the first position of the first sheet the first position A second position of the first sheet, the engaging hole having an opening region corresponding to at least a part of the cutout portion of the first sheet; An alternate laminated body with a second sheet having an opening area corresponding to the engaging hole of the first sheet at a corresponding second position and having a notch opening at the trailing edge is prepared. When the uppermost layer of the body is the first sheet, at the first position of each sheet, in the corresponding opening area of the cutout portion or the engaging hole of each sheet, from the lowermost layer of the sheet laminated body to the uppermost layer Correspondence between the cutout portion or the engagement hole of each sheet at the second position of each sheet when the uppermost layer of the sheet laminate is the second sheet And a second state in which the second engaging pin is penetrated from the lowermost layer to the uppermost layer of the sheet laminated body in an alternating manner. 2. A rectangular contour having four sides, one pair of the four sides facing each other being a side edge, and the other pair being a leading edge and a trailing edge, with a trailing edge at a first position along the trailing edge. A first sheet having a notch portion that is close to and open to the trailing edge, and has a second position along the trailing edge that is close to the trailing edge but has an engaging hole that does not open to the trailing edge; The first sheet has the same rectangular contour as that of the first sheet, and has a pair of side edges, a front edge, and a rear edge corresponding to the pair of side edges, front edges, and rear edges of the first sheet, respectively. A first position corresponding to the first position of an engaging hole having an opening region corresponding to at least a portion of the notch of the first sheet, the second of the first sheet A second sheet having an opening region corresponding to the engaging hole of the first sheet at a second position corresponding to the position and having a notch opening at the trailing edge. A sheet stacking table that supports the sheet stack, in a device that sends out only the uppermost layer sheet in the direction from the trailing edge to the leading edge along the surface of the sheet at a time, by an alternate stacking body with the sheet stack, Sheet driving means for driving the uppermost sheet of the sheet laminated body placed on the sheet placing table in the direction from the trailing edge to the leading edge along the surface of the sheet, and placed on the sheet placing table. First sheet that can selectively penetrate each sheet of the sheet stack from the bottom layer to the top layer of the sheet stack at the first position through the notch portion of each sheet or the corresponding opening area of the engaging hole. The engaging pin and each sheet of the sheet laminated body placed on the sheet mounting table at the second position through the corresponding notch portion of each sheet or the corresponding opening area of the engaging hole of the sheet laminated body. Second engagement capable of selectively penetrating from the bottom layer to the top layer One of the first engagement pin and the second engagement pin, and when the other is pushed up to a position where it penetrates the uppermost sheet of the sheet stack, the other does not reach the uppermost layer of the sheet stack. And an engaging pin drive means for moving them reciprocally. 3. A rectangular contour having four sides, one pair of the four sides facing each other as a side edge, the other pair as a front edge and a rear edge, and a rear edge at a first position along the rear edge. A first sheet having a notch portion that is close to and open to the trailing edge, and has an engaging hole that is close to the trailing edge but does not open to the trailing edge at a second position along the trailing edge; The sheet has the same rectangular contour as the one sheet, and has a pair of side edges, a front edge, and a rear edge corresponding to the pair of side edges, the front edge, and the rear edge of the first sheet, respectively. The first position corresponding to the first position of the sheet has an engagement hole having an opening region corresponding to at least a part of the cutout portion of the first sheet, and the second position of the first sheet. The second sheet having an opening region corresponding to the engaging hole of the first sheet at a second position corresponding to the position A sheet laminate in which sheets and sheets are alternately polymerized.