JP2008179416A - Zero taper stack - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a zero taper stack in a simple shape in the plan view which relaxes or avoids an excessive fitting that is the drawback of a cross-shaped zero taper stack. <P>SOLUTION: The zero taper stack in a hole form is provided in a conveyance tray which is laminated in a multiple levels for carrying a rectangular plate body. The zero taper stack includes a bottom surface having a Y-shape in a plan view and a side surface which is almost perpendicular to the bottom surface. The zero taper stack is formed with a linear corner 34 in a direction which is almost perpendicular to the bottom surface in a side surface. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a zero taper stack, a rectangular plate-shaped conveyance tray including the zero taper stack, and a conveyance tray kit including the conveyance tray and the rectangular plate-shaped body.
Such a transport tray has a dish-like shape opened upward, and is a transport tray for storing and transporting a rectangular plate-like body such as a liquid crystal panel.

Conventionally, when a relatively small display element such as a mobile liquid crystal panel is transported, a liquid crystal panel or the like is placed on the transport tray, and then transported in a multi-layered manner. Damage to panels and the like (particularly liquid crystal panel glass surfaces and polarizing plates) is prevented. The upper transport tray stacked in this manner also functions as a lid for the lower transport tray, and the uppermost transport tray serves only as a lid without accommodating a liquid crystal panel or the like [FIG. ,reference〕.
Such a transport tray is a vacuum molded product obtained by vacuum molding a plastic material such as polypropylene using a mold. The transport tray includes a recess-shaped storage portion for storing a liquid crystal panel or the like at the center thereof, and a so-called zero taper stack having a hole shape having a bottom surface mainly around the transport tray.
In this zero taper stack, the angle formed between the plane of the transport tray main body and the side surface of the hole is approximately 90 degrees, and the taper angle is zero. When another transport tray is stacked, the bottom surface of the upper zero taper stack fits into the opening of the lower zero taper stack, and the function of maintaining the stacked state of the transport tray can be achieved.

As such a zero taper stack, the following Patent Document 1 (hereinafter referred to as Document 1) proposes a zero taper stack having a bottom surface having a cross shape when viewed from below in a stacked state. When considering ease of operation (workability) and position fixability, ... (omitted) ... it is said that the cross shape has been determined to be most suitable.
However, it has been found that such a cruciform zero taper stack has a very large fit into the lower zero taper stack of the upper zero taper stack. When such excessive fitting occurs, first, the bottom of the upper tray comes into contact with the display element (liquid crystal panel) of the lower tray, and the display element is damaged, and second, it is fitted. The work of separating the zero taper stack becomes very complicated (usually because there are many zero taper stacks). Third, when the work of separating the fitted zero taper stack is performed, Due to elasticity, there is a problem that the display element is dropped and damaged from the transport tray. Furthermore, since the cross-sectional shape of the cross-shaped zero taper stack in plan view is complicated in plan view, the problem of high cost due to the poor workability of mold manufacturing, and the fact that the zero taper stack with relatively small dimensions cannot be manufactured. There was also a problem.

JP-A-11-198938

  SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problem, that is, to provide a zero taper stack having a simple plan view configuration that alleviates or avoids excessive fitting, which is a drawback of a cruciform zero taper stack. is there.

Means and effects for solving the problems

In order to solve the above-mentioned problems, the present inventors have studied the zero-taper stack in various plan views / bottom forms, and as a result of experiment on the fitting resistance, It is found that the zero taper stack having the above can increase the fitting resistance and can achieve a simple plan view / bottom form, thereby solving the above-mentioned problems. It has been completed.
That is, the present invention is a hole-shaped zero taper stack provided in a transport tray that can be stacked in multiple stages for transporting a rectangular plate-shaped body, and has a bottom surface having a Y-shape in plan view, A zero taper stack comprising: a side surface substantially perpendicular to the bottom surface, wherein a straight corner is formed in a direction substantially perpendicular to the bottom surface on the side surface.
According to the present invention, the invention-specific matters of the present invention, in particular, by adopting a zero taper stack form having a Y-shaped bottom surface in plan view and a side surface in which straight corners are formed, It has been experimentally proven that the Y-shaped zero taper stack of the present invention is significantly improved over the prior art cruciform zero taper stack. This increase in the fitting resistance can prevent the bottom of the upper tray from coming into contact with the display element of the lower tray and damage the display element, and can substantially avoid the work of separating the fitted stack. In addition, it was possible to achieve the technical effect of being able to substantially avoid the damage of dropping the display element from the transport tray.
In addition, by selecting the Y-shape as the plan view / bottom view form of the zero taper stack, a simple plan view form can be achieved as compared with the conventional technique which is a cross shape in plan view. It was possible to achieve the technical effect of making it possible to manufacture inexpensive molds by greatly improving workability, and making it possible to manufacture stacks with relatively small dimensions.
In other words, in order to form a mold for manufacturing a known stack having a cross shape in plan view, it is necessary to cut a cylindrical base mold from four places on the side surface. This is because it is sufficient to cut three places, and since there are fewer cutting places than in the past, it is possible to manufacture a stack having a relatively small size.

Preferably, corresponding to the Y-shaped bottom surface form, the side surface includes a projecting side surface projecting out of the system and a notched side surface recessed in the system, and the linear corner is A boundary between the protruding side surface portion and the notched side surface portion is formed.
According to the second aspect of the present invention, there is provided a transport tray capable of being stacked in multiple stages for transporting a rectangular plate-like body, comprising the zero taper stack of the present invention. A rectangular plate-shaped conveyance tray is provided.
According to a third aspect of the present invention, there is provided a transport tray kit comprising the transport tray for a rectangular plate according to the present invention and the rectangular plate stored in the tray. provide.

As described above, the present invention is a hole-shaped zero taper stack (1) provided in a transport tray (101) that can be stacked in multiple stages for transporting a rectangular plate (24). A bottom surface (31) having a Y-shape in plan view, and a side surface (32) substantially perpendicular to the bottom surface (31), and the side surface (32) with respect to the bottom surface (31) A zero taper stack (1) is provided, characterized in that straight corners (34) are formed in a substantially vertical direction (see attached FIG. 1 and the like).
In general, a zero taper stack has an uneven thickness phenomenon in a peripheral portion that forms a bottom surface shape (for example, a circumferential portion in the case of a circular bottom surface shape). It has been thought that the peripheral portion where the meat phenomenon occurs becomes longer, and therefore, the resistance to fitting of the peripheral portion of the bottom surface increases.
On the other hand, the planar view Y-shaped zero taper stack (hereinafter, sometimes referred to as Y-shaped stack) of the present invention has a bottom shape that is lower than the conventional planar cross-shaped zero taper stack (hereinafter, sometimes referred to as cross-shaped stack). Simple. Nevertheless, according to the experimental results of the present invention, surprisingly, the Y-shaped stack of the present invention shows excellent fit resistance, which is a straight corner formed on the side. It is thought to be caused by the part.
That is, according to the present invention, it seems that by forming a unique form called a straight corner on the side surface, fitting resistance is increased due to this unique form.

“Rectangular plate-like body” refers to a high-performance device or the like, and not only a rectangular plate-like body such as a display device, for example, a liquid crystal panel, particularly a mobile liquid crystal panel, but also an LSI bare chip on a tape-like insulating film on which lead wiring is formed. A rectangular plate with accessories, such as a liquid crystal panel with TCP mounted on a liquid crystal panel with a tape carrier package (TCP) connected with leads and a liquid crystal panel with printed circuit board mounted on a liquid crystal panel Shapes are also included.
The rectangular plate-shaped transport tray (hereinafter referred to as a transport tray) has a dish-like shape that opens upward, and stores and transports the rectangular plate-shaped body, such as a sheet of polypropylene or polystyrene. This is a molded product obtained by vacuum-forming a resin material in the form of a mold.
In this specification, the terms “upper / lower” and “planar view” are based on a state in which the transport trays of the present invention are stacked in multiple stages. Therefore, the term “plan view” is based on the state seen from above or below.

Next, the present invention will be described in more detail by describing the best mode for carrying out the present invention with reference to the attached drawings. However, the present invention is not limited to these embodiments and the like. Absent.
FIG. 1 is a perspective view from below showing an embodiment of a zero taper stack of the present invention. In other drawings including FIG. 1, the same elements are sometimes omitted in the drawings and the description thereof is omitted in some cases.
-Zero taper stack 1-embodiment-
The zero taper stack 1 is in the form of a hollow hole having a bottom surface 31 having a Y-shape in plan view and a side surface 32 substantially perpendicular to the bottom surface 31.
<Side 32>
By making the bottom surface 31 into a Y-shaped form in a plan view, a relatively projecting side surface portion 33, a relatively recessed notched side surface portion 35, and an angle corresponding to a boundary portion existing therebetween. A side surface 32 composed of the portion 34 is formed.
<< Projecting side surface portion 33 / notched side surface portion 35 >>
The protruding side surface portion 33 protrudes from the center of the zero taper stack 1 to the outside of the system, while the notched side surface portion 35 is recessed from the outside of the system to the inside of the system (the center of the zero taper stack 1). Thus, three are formed each.
Further, the three protruding side surfaces 33 are formed in a curved surface shape protruding outside the system, and have the same surface area. Similarly, the three cut-out side portions 35 are also formed in a curved shape so as to be recessed in the system and have the same surface area. Thus, by having the side parts 33 and 35 of the same form, the mechanical strength of the zero taper stack 1 is stabilized.
<< Corner 34 >>
The corner portion 34 forms a pointed linear shape with almost no roundness in the height direction of the side surface 32 of the zero taper stack 1, and among the constituent portions, the boundary portion with the bottom surface 31, that is, the bottom surface 31 and The edge portion 38 (schematically illustrated by a black circle in FIG. 1), which corresponds to three boundary portions between the protruding side surface portion 33 and the notched side surface portion 35, has a sharp pointed shape. Compared to the conventional technology of a rounded side surface shape without such a corner (cross-shaped zero taper stack of Document 1 / Sx in FIG. 3 of the present specification), the corner 34, particularly the edge 38. In the vacuum molding, a thickness unevenness phenomenon in which the resin material is biased and the thickness increases is likely to occur, whereby the fitting resistance of the zero taper stack 1 can be increased.

<<< Bottom 31 >>>
As described above, the bottom surface 31 has a Y-shaped form in plan view, and this Y-shaped form is a form in which a notch arc portion 36 having a predetermined radius R is cut out from a virtual circle 37 as shown in FIG. . The former virtual circle 37 has three protruding arc portions 39 corresponding to the boundary portion between the bottom surface 31 and the three protruding side surface portions 33 as a part of the circle, while the latter notched arc portion 36 is included in the system. It is a part of a circle having a predetermined radius R that is recessed. The Y-shaped form is expressed by the formula: area ratio r (%) = D ₁ / D ₀ × 100 [where D ₀ is the area of the virtual circle 37, and D ₁ is the area of the bottom surface 31. ] (See Fitting Resistance Test II below).
The mold for this embodiment is formed by cutting from a base mold portion having a diameter of 12 mm and having a circular shape in plan view (that is, a cylindrical portion).

<Fitting Resistance Test I: Difference due to Bottom Form>
The inventors of the present invention have tested the fit resistance with respect to zero taper stacks in various plan view forms (bottom face forms). FIG. 2 is a plan view of the test conveyance tray 102, and FIG. 3 is a table showing the result of the fitting resistance test I. As shown in FIG.
<< Sample Preparation >>
First, heat-soften a polypropylene sheet (manufactured by Seadam Co., Ltd.), set a mold on the softened sheet, make a vacuum between the softened sheet and the mold, and attach the softened sheet to the mold. Molded. After cooling, the vacuum was released and the molded product was taken out of the mold to produce two test transport trays 102 as shown in FIG.
The test conveyance tray 102 is formed with a zero taper stack Sy having a Y-shape in plan view according to the present invention, and as a comparative example, a zero taper stack So having a circular shape in plan view, and a zero taper stack Si having a I-shape in plan view. And a zero taper stack Sx having a cross shape in plan view. A cylindrical base mold having a diameter of 12 mm and a height of 12 mm was used as a base mold, and the comparative example So having a circular shape in plan view was not processed, and the other plan view forms were formed by a predetermined cutting process. . The zero taper stack (Sy, So, Si, Sx) is formed at three locations for Sy and Sx, and at two locations for So and Si in order to eliminate the influence of the arrangement on the tray. It was. The test transport tray 102 is provided with a recess-shaped storage portion 6 for storing the rectangular plate-like body 24 at the center thereof.

  It should be noted that the present invention Sy has a straight corner 34 on its side 32 (see FIG. 3). While the comparative example Si has the same shape as the linear corner portion 34, the comparative example Sx (Document 1) does not have the same shape. That is, unlike the present invention Sy, the side surface of the comparative example Sx is smoothly rounded into a curved shape.

<< Measurement of fit resistance >>
The fit resistance was measured as follows. First, the other test transport tray 102 is lightly stacked on one test transport tray 102, and the upper zero taper stack and the lower zero taper stack are disposed so as to be positioned on a substantially vertical line. Next, the upper zero taper stack is placed on the upper surface of the upper zero taper stack with the tip of the load measuring device (push-pull gauge, MODEL-RC9500S-200N-A TYPE, manufactured by AIKOH ENGINEERING). Press vertically downward to fit into the side zero taper stack.
Since the zero taper stack has a hollow space inside and exhibits a certain degree of elasticity, the upper zero taper stack fits into the hollow space of the lower zero taper stack by being pressed against the lower zero taper stack. Go. At this time, first, the upper zero taper stack is slightly fitted into the upper edge portion inside the lower zero taper stack, and a resistance force is generated to maintain the state even if the pressing force is increased. This resistance is referred to as resistance. If the pressing force is further increased, the pressing force cannot be withstood, and the upper zero taper stack fits deeply into the lower zero taper stack. At this time, the pressing force rapidly decreases. In this test, the maximum pressing force immediately before the pressing force suddenly decreased was measured as the fitting resistance force τ (unit [N]). When the fitting resistance force τ is large, excessive fitting of the zero taper stack can be reduced or avoided.
In accordance with the measurement method described above, each of Comparative Example So, Comparative Example Si (each two sets of samples), Comparative Example Sx, and the present invention Sy (each three sets of samples) each have 15 fit resistance tests. Went. The results are shown in Table 1 (FIG. 3).

<< Test results and discussion >>
As can be seen from Table 1 (FIG. 3), the fitting resistance τ increases in the order of Comparative Example So, Comparative Example Si, Comparative Example Sx, and Sy of the present invention, and Sy of the present invention has excellent fitting resistance. It is clear that Further, the fitting resistance force τ of the present invention Sy having a Y-shape in plan view is improved by about 10% compared to the fitting resistance force τ of Sx having a cross-shape in plan view (known technology, Patent Document 1). (97.56N / 88.69N = about 1.1).
The Y-shaped present invention Sy and the cross-shaped comparative example Sx showed better fitting resistance than the other comparative examples (circular, I-shaped) because the former is more complicated than the latter The reason for this is that the present invention Sy has better fit resistance than the comparative example Sx, while having a plan view form, and therefore, an uneven thickness phenomenon is likely to occur.
The four projecting side portions of the comparative example Sx are smoothly rounded as a whole, whereas the three projecting side portions 33 of the present invention Sy have sharp straight corners. . During vacuum forming, the smoothly rounded protruding side surface portion (particularly, the boundary portion between the protruding side surface portion and the bottom surface) of Comparative Example Sx is formed smoothly along the mold, resulting in uneven thickness phenomenon. On the other hand, the linear corner portion 34 of the present invention, especially the edge portion 38, is liable to be biased in the resin material, causing a thickness deviation phenomenon and increasing the thickness, and as a result, an excellent fit. It is considered to show resistance.

<Fitting Resistance Test II: Difference due to area ratio r of Y-shape>
As described above, the Y-shaped form is defined by the formula: area ratio r (%) = D ₁ / D ₀ × 100 [D ₀ is the area of the virtual circle 37 and D ₁ is the area of the bottom surface 31]. An experiment was conducted on the relationship between the area ratio r and the fitting resistance.
FIG. 9 is a graph showing the relationship between the area ratio r and the fitting resistance τ.
<< Sample Preparation >>
According to the method of the above-mentioned fitting resistance test I (hereinafter, test I), the area D ₀ of the virtual circle 37 is made constant, and the area D _{1 of the} bottom surface 31 is changed by the change in the radius R of the notch arc portion 36. Various samples K1 to K10 were prepared. However, zero taper stacks 1 having the same area ratio r were formed at four locations on one transport tray, and a total of 10 test transport trays were manufactured.
<< Measurement of fit resistance >>
In accordance with the method of Test Example I, fit resistance was measured. However, it measured 5 times about each sample K1-K10 (above, 10 sets of samples). Therefore, each sample was measured 20 times (= 5 times × 4 locations), and the obtained measurement values were averaged. The results are shown in Table 2, and based on this result, the relationship between the area ratio r and the fitting resistance τ is shown as a graph in FIG. Sample K4 corresponds to the Y-shaped zero taper stack of Test I, and K10 corresponds to the circular zero taper stack of Test I.

<< Test results and discussion >>
As can be seen from the graph of FIG. 9, the fitting resistance force τ has two points of the area ratio r where the resistance force τ rapidly decreases, and there is a maximum value with respect to the area ratio r. That is, from this graph, a suitable area ratio r can be determined with respect to the fitting resistance force τ.
Thus, the preferred area ratio r is more than 0 and less than 100, and the more preferred area ratio r is 42 to 71%, especially 44 to 58%. Such a result is obtained as follows.
The Y-shaped form becomes thinner as the area ratio r is made smaller. That is, the arc length of the projecting arc portion 39 is further shortened. For this reason, since the thickness of the uneven thickness portion formed at the corner portion 34, particularly the edge 38, is constant without depending on the area ratio r, the ratio of the uneven thickness portion to the arc length is the area ratio. As r becomes smaller (becomes thinner), it becomes larger and, as a result, fit resistance increases.
On the other hand, if the thickness is excessively thin, the zero taper stack 1 itself, that is, the side 32 is less bent. When the bending resistance is excessively reduced, the upper stage / zero taper stack 1 is displaced from the vertical direction when pressed, and easily fits into the lower stage / zero taper stack 1. As a result, it is considered that the fitting resistance is lowered.

-Conveying tray 101 for rectangular plate-shaped body--Embodiment-
4 is a plan view showing an embodiment of the rectangular plate-shaped conveyance tray of the present invention having the embodiment of the zero taper stack shown in FIG. 1, and FIG. 5 is for the rectangular plate-shaped body shown in FIG. FIG. 6 is a partially enlarged view of a part of the transport tray, FIG. 6 is a partial cross-sectional view of the rectangular plate-shaped transport tray shown in FIG. 5 or FIG. 4, and FIG. FIG. 5 is a partial sectional view taken along the line BB in FIG. 5 and (b) is a sectional view of the zero taper stack 1b in FIG. 4 taken along the line AA in FIG. FIG. 7 is a plan view seen from above showing a state in which the rectangular plate (liquid crystal panel with a printed circuit board) is stored in the storage portion of the rectangular plate-shaped conveyance tray shown in FIG.
The transport tray 101 of the present invention has a substantially rectangular shape in plan view when viewed from above, and includes a transport tray main body 101 ′. The main body 101 ′ includes a zero taper stack 1 and a storage portion for a rectangular plate-shaped body. 6 and an inverted taper stack 2 having a semicircular shape in plan view when viewed from above.
<Zero taper stack 1a-c>
In the zero taper stack 1 of the present invention, the zero taper stack 1a is provided along each side of the rectangle as the embodiment, and the zero taper stack 1b is provided in the system rather than the zero taper stack 1a (FIG. 4). (See FIG. 6). The former zero taper stack 1a is formed such that its upper end is the same as the surface of the transport tray body 101 ', while the latter zero taper stack 1b is lower than the surface of the transport tray body 101'. (See FIG. 6B). Such a stepped portion can improve the fitting resistance.
The zero taper stacks 1a and 1b are formed by using a base mold (diameter: 12 mm) having the same dimensions as those of the above embodiment, while the zero taper stack 1c provided on the grip portion 9 of the transport tray 101 has such a base. It is formed using a base mold (diameter 8 mm) having a smaller size than the mold. Thus, the smaller zero taper stack 1c increases the fitting resistance as in the case of the thinner Y-shaped configuration as described above, but the excessively small zero taper stack has a bending resistance. As a result, the resistance to fitting decreases.

<Storage unit 6 for rectangular plate-like body>
The rectangular plate-shaped storage portion 6 is a tapered concave portion having a taper angle of 95 degrees (an angle formed between the transport tray main body 101 ′ and the side surface of the storage portion 6) (FIG. 6A), and has a rectangular plate shape. A liquid crystal panel 24 with a printed circuit board can be accommodated as the body 24 (FIG. 7). The liquid crystal panel 24 includes a liquid crystal panel body 21, a printed board 22, and a tab 23.
<Reverse taper stack 2>
As described above, the transport tray main body 101 ′ includes the inverted taper stack 2. This reverse taper stack 2 is mainly formed in the vicinity of the storage portion 6 (FIG. 7), and is composed of an upper surface 10 having a semicircular shape in plan view and a side surface 11 connected to the upper surface 10 as viewed from above. The angle is about 80 degrees, which is different from a taper indicating an angle exceeding 90 degrees (FIG. 6A). That is, since the reverse taper is formed, the upper reverse taper stack 2 does not fit into the lower reverse taper stack 2 in the stacked state, and the spacers that keep the interval between the upper and lower transport trays constant are maintained. Play a function.
<Other elements>
The transport tray 101 includes four corners 3 and 4 that are rectangular in plan view as other elements (see FIG. 4). The three corners 4 are linear, and the other one corner 3 forms an arc shape, whereby the direction is easily determined when stacking the asymmetrical conveyance trays 101. (FIG. 4). Further, as another element, the transport tray 101 includes ribs 7 on its outer periphery (FIG. 5), and can reinforce the edge 5 that is the outer periphery. Further, around the storage portion 6, there is provided a concave finger removal portion 8 for storing the rectangular plate-shaped body 24 in the transport tray and for taking out the rectangular plate-shaped body 24 stored in the transport tray (see FIG. 7) This facilitates accommodation / removal of the rectangular plate-like body 24.

The transport tray 101 of the present invention is used as follows, for example. FIG. 8 is a perspective view showing a process until the rectangular plate-shaped conveyance tray of the present invention is packaged.
First, the liquid crystal panel 25 as a rectangular plate is placed on the transport tray 101, the placed transport trays 101 are stacked in multiple stages, and the stacked transport trays 101 are double-wrapped in cardboard boxes 41 and 42. To do. The packaged stacked conveyance tray 101 can be applied to distribution in factories, distribution between factories, shipment to overseas, and the like. The transport trays 101 stacked in multiple stages can also be packed in cardboard boxes 41 and 42 after being wrapped with aluminum foil and degassed inside.

The perspective view seen from the bottom which shows the embodiment of the zero taper stack of the present invention. FIG. 2 is a plan view of the test transport tray 102. The table | surface which shows the result of the fitting resistance test I. FIG. The top view which shows embodiment of the conveyance tray for rectangular plate-shaped bodies of this invention provided with embodiment of the zero taper stack shown in FIG. The partial enlarged view which expanded a part of conveyance tray for rectangular plate-shaped bodies shown in FIG. FIG. 5 is a partial cross-sectional view of the rectangular plate-shaped conveyance tray shown in FIG. 5 or 4, and (a) shows a state in which two conveyance trays are stacked and is cut out along the line BB in FIG. 5. FIG. 5B is a sectional view of the zero taper stack 1b of FIG. 4 cut along the line AA of FIG. The top view seen from the top which shows the state which accommodated the rectangular plate-shaped body (liquid crystal panel with a printed circuit board) in the accommodating part of the conveyance tray for rectangular plate-shaped bodies shown in FIG. The perspective view which shows the process until it packages the conveyance tray for rectangular plate-shaped bodies of this invention. The graph which shows the relationship between area ratio r and fitting resistance force (tau).

Explanation of symbols

1: Zero taper stack 24: Rectangular plate body 31: Bottom surface 32: Side surface 34: Corner portion 101: Transport tray for rectangular plate body

Claims (4)

A zero taper stack in the form of a hole provided in a transport tray that can be stacked in multiple stages for transporting a rectangular plate-shaped body,
A bottom surface having a Y-shape in plan view and a side surface substantially perpendicular to the bottom surface, and a linear corner is formed on the side surface in a direction substantially perpendicular to the bottom surface. Zero taper stack characterized by Corresponding to the Y-shaped bottom surface form, the side surface includes a protruding side surface portion protruding outside the system, and a notched side surface portion recessed in the system,
The zero taper stack according to claim 1, wherein the straight corner portion forms a boundary between the protruding side surface portion and the notched side surface portion.   A transport tray for transporting a rectangular plate, which can be stacked in multiple stages, comprising the zero taper stack according to claim 1. A transport tray kit comprising the rectangular plate-shaped material transport tray according to claim 3 and a rectangular plate-shaped material stored in the tray.

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