JP3235008U - Box sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a box sheet which can easily maintain a sealed state of a lid portion of a box body. SOLUTION: A pair of first side surface panels 1a and 1b and a pair of second side surface panels 2a and 2b facing each other in an assembled state extend from an upper edge of a pair of first side surface panels, and the tip edges are connected to each other in the assembled state. A box sheet 10 comprising a pair of outer lid flaps 3a and 3b to be abutted and a pair of inner lid flaps 4a and 4b extending from the upper edge of a pair of second side panel panels. A pair of break lines 13 extending from the tip edge toward the base end side are formed at intervals in the width direction, and an insertion piece 14 is defined between the pair of break lines, and a pair of lids. An insertion port into which the insertion piece is inserted is provided at the seam portion on the side close to the insertion piece of the outer flap, and the insertion port has a U-shaped slit 11a that is convex toward the opposite side of the insertion piece. , Defined by an easy-to-bend line 11b connecting both ends of the slit. [Selection diagram] Fig. 1

Description

The present invention relates to a box sheet.

Box bodies assembled from box sheets such as corrugated cardboard sheets are used for storing and transporting articles. The box sheet includes a pair of first side panel and a pair of second side panels facing each other in the assembled state, a pair of outer lid flaps extending from the upper edge of the pair of first side panels, and a pair of first side panels. It is known that a pair of inner flaps extending from the upper edge of the two side panels is provided, and the lid portion of the box body can be assembled by abutting the tip edges of the pair of outer lid flaps.

Further, as this box sheet, a groove is provided at the joint portion of the pair of outer lid flaps, and the pair of inner lid flaps is provided with the sill insertion flap 6 to be inserted into the groove, thereby forming a sealing tape. It has been proposed that the lid can be assembled without using it (see Patent Document 1).

Jitsuzensho No. 51-20827

Patent Document 1 describes that a 篏 insertion tip portion to be inserted into a groove is provided at the tip end portion of the 篏 insertion flap. In the box sheet described in Patent Document 1, the tip portion for inserting a sword is bent at a right angle, and the tip portion for shaving is inserted substantially perpendicular to the groove.

However, according to this configuration, the tip portion for inserting the box is easily pulled out from the groove, and it is difficult to maintain the sealed state of the lid portion of the box body.

The present invention has been made based on such circumstances, and an object of the present invention is to provide a box sheet that can easily maintain the sealed state of the lid of the box body.

The box sheet according to one aspect of the present invention extends from the pair of first side panel and the pair of second side panels facing each other in the assembled state and the upper edge of the pair of first side panels, and the tip in the assembled state. A box sheet comprising a pair of outer lid flaps whose edges are butted against each other and a pair of inner lid flaps extending from the upper edge of the pair of second side panel panels, on one of the inner lid flaps. A pair of break lines extending from the tip edge toward the base end side are formed at intervals in the width direction, and an insertion piece is defined between the pair of break lines, and the pair of outer lid flaps. An insertion slot into which the insertion piece is inserted is provided at a seam portion on the side close to the insertion piece, and the insertion opening is a U-shaped slit that is convex toward the opposite side of the insertion piece. And an easy-to-bend line connecting both ends of the slit.

The box sheet according to one aspect of the present invention can easily maintain the sealed state of the lid portion of the box body.

FIG. 1 is a schematic plan view showing a box sheet according to an embodiment of the present invention. FIG. 2 is a schematic perspective view of a box body formed by assembling the box sheet of FIG. 1. FIG. 3 is a schematic plan view of the box body of FIG. FIG. 4 is a schematic plan view showing a state before the insertion piece in the box body of FIG. 2 is inserted into the insertion slot. FIG. 5 is a partially enlarged view of the box sheet of FIG. FIG. 6 is a sectional view taken along line VI-VI of the box body of FIG.

[Explanation of Embodiment of the present invention]
First, embodiments of the present invention will be listed and described.

The box sheet according to one aspect of the present invention extends from the pair of first side panel and the pair of second side panels facing each other in the assembled state and the upper edge of the pair of first side panels, and the tip in the assembled state. A box sheet comprising a pair of outer lid flaps whose edges are butted against each other and a pair of inner lid flaps extending from the upper edge of the pair of second side panel panels, on one of the inner lid flaps. A pair of break lines extending from the tip edge toward the base end side are formed at intervals in the width direction, and an insertion piece is defined between the pair of break lines, and the pair of outer lid flaps. An insertion slot into which the insertion piece is inserted is provided at a seam portion on the side close to the insertion piece, and the insertion opening is a U-shaped slit that is convex toward the opposite side of the insertion piece. And an easy-to-bend line connecting both ends of the slit.

The box sheet seals the lid of the box by inserting the insertion piece defined in the one inner flap of the above into the insertion opening formed at the joint portion of the pair of outer flaps of the lid from above. can do. In the box sheet, the insertion port is defined by a U-shaped slit that is convex toward the opposite side of the insertion piece and an easy-to-bend line that connects both ends of the slit. A tongue piece defined by the slit and the easy-to-bend line is formed at the seam portion of the flap outside the lid. In the box sheet, with the insertion piece inserted into the insertion opening, the insertion piece can be sandwiched between the tips of the pair of outer lid flaps and the tongue piece. Therefore, according to the box sheet, it is easy to maintain the sealed state of the lid portion of the box body.

It is preferable that the insertion piece is provided from the base end edge of the flap inside the lid. As described above, since the insertion piece is provided from the base end edge of the flap inside the lid, the insertion piece can be easily inserted into the insertion opening.

The insertion piece is divided into a base portion, an intermediate portion, and a tip portion from the base end side to the tip end side, and the protrusion direction length of the base portion is 1 to 3 times the sheet thickness. Yes, the length of the intermediate portion in the protruding direction is equal to or greater than the distance from the base end edge of the one inner lid flap to the easy-to-bend line in the plan view of the assembled state, and the above-mentioned is from the base end edge of the one inner lid flap. It should be less than or equal to the maximum distance to the slit. In this way, the insertion piece is divided into a base portion, an intermediate portion, and a tip portion from the base end side to the tip end side, and the protrusion direction length of the base portion is at least 1 times the sheet thickness. The length in the protruding direction of the intermediate portion is 3 times or less, the distance from the base end edge of the one inner lid flap to the easy-to-bend line in the plan view of the assembled state or more, and the base of the one inner lid flap. When the distance from the edge to the slit is not more than the maximum distance, the tip portion can be inserted into the insertion slot in a state of being inclined with respect to the pair of outer lid flaps. As a result, the insertion piece can be easily and surely sandwiched between the tips of the pair of outer lid flaps and the tongue piece.

The ratio of the width of the tip edge of the intermediate portion to the length of the easily bendable line is preferably 0.8 or more and 1 or less. As described above, when the ratio of the width of the tip edge of the intermediate portion to the length of the easy-to-bend line is within the above range, the insertion piece can be easily and surely inserted into the insertion opening.

It is preferable that the tip portion is widened in the middle portion in the protruding direction. As described above, since the tip portion is widened at the intermediate portion in the protruding direction, the state in which the insertion piece is inserted into the insertion port can be more reliably maintained.

In the present invention, the "U-shape" includes a square U-shape or a shape similar to a square U-shape.

[Details of the Embodiment of the present invention]
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings as appropriate.

[Box sheet]
The box sheet 10 of FIG. 1 extends from the pair of first side surface panels 1a and 1b and the pair of second side surface panels 2a and 2b and the pair of first side surface panels 1a and 1b facing each other in the assembled state. , A pair of outer lid flaps 3a and 3b whose tip edges are butted against each other in the assembled state, and a pair of inner lid flaps (first inner flap 4a and) extending from the upper edges of the pair of second side surface panels 2a and 2b. It is provided with a second inner flap 4b). The pair of first side surface panels 1a and 1b and the pair of second side surface panels 2a and 2b are alternately connected in the left-right direction. Further, the box sheet 10 includes a pair of outer bottom flaps (first outer flap 5a and second outer flap 5b) extending from the lower edges of the pair of first side surface panels 1a and 1b, and a pair of first side flaps. 2 A pair of in-bottom flaps 6a and 6b extending from the lower edges of the side panels 2a and 2b, and extending from the outer side edges of the first side panel 1a located on the outer side in the left-right direction (left side in FIG. 1). It is equipped with a step 7 to be used. In the present invention, the "left-right direction" means the horizontal direction in a general usage mode assumed in a box body formed by assembling a box sheet. "Upper" means an upper part based on the left-right direction, and "lower" means a lower part based on the left-right direction. The "inside" means the inside of the box body formed by assembling the box sheet, and the "outside" means the outside of the box body. Further, in FIG. 1, a thick solid line indicates a cutting line formed by cutting a sheet, and a thin solid line indicates a ruled line formed by pressing one side of the sheet.

The box sheet 10 is assembled into the box body 20 shown in FIGS. 2 and 3. The procedure for assembling the box sheet 10 into the box body 20 will be described. First, the first side panel 1a located on the outside in the left-right direction (left side in FIG. 1) is folded onto the inner surface of the second side panel 2a connected to the first side panel 1a, and the outside in the left-right direction (right side in FIG. 1). The second side surface panel 2b located at is folded onto the inner surface of the first side surface panel 1b connected to the second side surface panel 2b, and the joint 7 is attached to the inner surface of the folded second side surface panel 2b. Next, the pair of first side surface panels 1a and 1b and the pair of second side surface panels 2a and 2b connected endlessly are expanded into a square cylinder, and then the pair of bottom flaps 6a and 6b are bent inward. Further, the bottom of the box body 20 is assembled by bending the first outer flap 5a and the second outer flap 5b inward and engaging the tip edges with each other. Subsequently, the pair of side pieces 15 of the first inner flap 4a and the second inner flap 4b, which will be described later, are bent inward, and the pair of outer lid flaps 3a and 3b are bent inward so that the tip edges are abutted against each other. Then, the lid portion of the box body 20 is assembled by inserting the insertion piece 14 described later in the second inner flap 4b into the insertion opening 11 formed in the joint portion of the pair of outer lid flaps 3a and 3b. A boxing tape (not shown) may be attached to the abutting portion between the pair of outer lid flaps 3a and 3b in the box body 20.

The box sheet 10 is formed of one sheet. The sheet used for the box sheet 10 is not particularly limited as long as it has enough strength to maintain the shape of the box body 20 formed by assembling the box sheet 10, and is not particularly limited, for example, a corrugated cardboard sheet, cardboard, or the like. Examples thereof include a paper sheet, a synthetic resin sheet, and a laminated sheet of a paper sheet and a synthetic resin sheet. Among them, a paper sheet is preferable, and a corrugated cardboard sheet is particularly preferable, from the viewpoints of workability, shock absorption, handleability, recyclability, economy and the like. The corrugated cardboard forming the box sheet 10 is a corrugated cardboard in which a core formed of a base paper in a wavy shape is bonded to a liner. For example, a core formed in a wave shape is bonded to a single liner. Single-sided corrugated cardboard sheet, double-sided corrugated cardboard sheet with a liner attached to the top of the single-sided corrugated cardboard, double-sided corrugated board sheet with the top of the single-sided corrugated cardboard attached to one side of the double-sided corrugated cardboard, and one side to one side of the double-sided corrugated cardboard sheet. Examples thereof include a double-sided corrugated cardboard sheet in which the tops of corrugated cardboard sheets are further bonded. Among these, double-sided corrugated cardboard sheets are preferable from the viewpoints of workability, economy, durability and the like.

(1st side panel)
The pair of first side surface panels 1a and 1b are formed in a rectangular shape and substantially the same shape. The left-right length of the first side surface panels 1a and 1b is larger than the left-right length of the second side surface panels 2a and 2b. That is, the first side surface panels 1a and 1b are length surface panels constituting the length surface in the box body 20.

The length of the first side surface panels 1a and 1b in the left-right direction can be appropriately set based on the size and quantity of the articles to be accommodated in the box body 20, but can be set to, for example, 15 cm or more and 50 cm or less. The vertical length of the first side surface panels 1a and 1b can be appropriately set based on the size and quantity of the articles to be accommodated in the box body 20, but can be, for example, 5 cm or more and 30 cm or less.

(Second side panel)
The pair of second side surface panels 2a and 2b are formed in a rectangular shape and substantially the same shape. The second side surface panels 2a and 2b are width surface panels constituting the width surface of the box body 20. The length of the second side surface panels 2a and 2b in the left-right direction can be appropriately set based on the size and quantity of the articles to be accommodated in the box body 20, but can be set to, for example, 10 cm or more and 30 cm or less. The vertical length of the second side surface panels 2a and 2b can be the same as the vertical length of the first side surface panels 1a and 1b.

(Flap outside the lid)
The pair of outer lid flaps 3a and 3b are formed in a substantially rectangular shape. The outer lid flaps 3a and 3b have substantially the same width as the left-right length of the first side surface panels 1a and 1b. The length of the outer lid flaps 3a and 3b in the extending direction is approximately ½ of the length of the second side surface panels 2a and 2b in the left-right direction.

As shown in FIGS. 2 to 4, the pair of outer lid flaps 3a and 3b has a seam portion on the side close to the insertion piece 14 (a seam portion on the side close to the second inner flap 4b in the assembled state). Has an insertion slot 11 into which the insertion piece 14 is inserted. The insertion port 11 is formed so as to straddle the pair of outer lid flaps 3a and 3b.

As shown in FIG. 4, the insertion port 11 is defined by a U-shaped slit 11a that is convex toward the opposite side of the insertion piece 14, and an easy-to-bend line 11b that connects both ends of the slit 11a. A tongue piece 12 is formed at the joint portion of the pair of outer lid flaps 3a and 3b by the slit 11a and the easily bendable line 11b.

The slits 11a are a pair of a first portion extending parallel to the base end edge of the second inner flap 4b in a plan view in an assembled state, and a pair connected to both ends of the first portion and extending toward the second inner flap 4b. It has a second part. The easy-to-bend line 11b is linear and extends in parallel with the first portion.

(Flap in the first lid)
The first flap 4a in the lid is formed in a rectangular shape. The flap 4a in the first lid has substantially the same width as the length in the left-right direction of the second side surface panel 2a. The extension direction length of the first inner flap 4a can be the same as the extension direction length of the outer lid flaps 3a and 3b.

(Flap in the second lid)
The second inner flap 4b is formed in a rectangular shape. The flap 4b in the second lid has substantially the same width as the length in the left-right direction of the second side surface panel 2b. The extension direction length of the second inner flap 4b can be the same as the extension direction length of the outer lid flaps 3a and 3b.

As shown in FIGS. 1 and 5, the second inner flap 4b is formed with a pair of breaking lines 13 extending from the tip edge toward the proximal end side at intervals in the width direction. In the second inner flap 4b, the insertion piece 14 is defined between the pair of break lines 13. Further, in the second lid inner flap 4b, a pair of side pieces 15 are defined on both sides of the insertion piece 14 via a break line 13. As the breaking line 13, in addition to the cutting line for preliminarily dividing the second inner flap 4b into the insertion piece 14 and the pair of side pieces 15, the second inner flap 4b is inserted into the insertion piece 14 and the pair of side pieces 15. Includes breakable lines that are separable to and from.

The insertion piece 14 is provided from the base end edge of the second inner flap 4b. That is, the pair of break lines 13 extends from the tip edge to the proximal edge of the second inner flap 4b. In the box sheet 10, the insertion piece 14 is provided from the base end edge of the second lid inner flap 4b, so that the insertion piece 14 can be easily inserted into the insertion port 11.

As shown in FIG. 5, the insertion piece 14 is divided into a base portion 14a, an intermediate portion 14b, and a tip portion 14c from the base end side to the tip end side. Easy-to-bend lines are formed at the boundary line between the base portion 14a and the intermediate portion 14b and at the boundary line between the intermediate portion 14b and the tip portion 14c, respectively. These easy-to-bend lines extend parallel to the proximal edge of the second inner flap 4b.

The lower limit of the projecting direction length L1 of the base portion 14a is preferably 1 times the sheet thickness. On the other hand, the upper limit of the projecting direction length L1 of the base portion 14a is preferably three times the sheet thickness, and more preferably twice the sheet thickness. If the length L1 in the protruding direction does not reach the lower limit, it may be difficult to superimpose the intermediate portion 14b of the insertion piece 14 on the upper surfaces of the pair of outer lid flaps 3a and 3b. On the contrary, when the protrusion direction length L1 exceeds the upper limit, the base end side of the intermediate portion 14b may be lifted from the upper surfaces of the pair of outer lid flaps 3a and 3b.

As shown in FIGS. 4 and 5, the protrusion direction length L2 of the intermediate portion 14b is an easy-to-bend line 11b (defining the insertion port 11) from the base end edge of the second inner flap 4b in the plan view of the assembled state. The distance D1 or more to the easy-to-bend line 11b) and the maximum distance D2 from the base end edge of the second inner flap 4b to the slit 11a (that is, the first portion of the slit 11a from the base end edge of the second inner flap 4b). Interval up to)) is preferably less than or equal to.

In the box sheet 10, the insertion piece 14 is divided into a base portion 14a, an intermediate portion 14b, and a tip portion 14c from the base end side to the tip end side, and the length L1 of the base portion 14a in the protruding direction is defined as the base portion 14a. The thickness is 1 to 3 times the sheet thickness, and the protrusion length L2 of the intermediate portion 14b is the distance D1 or more from the base end edge of the second inner flap 4b to the easily bendable line 11b in the plan view of the assembled state. Moreover, the maximum distance D2 or less from the base end edge of the second inner flap 4b to the slit 11a is equal to or less than the maximum distance D2. Can be inserted into the insertion slot 11. As a result, the insertion piece 14 can be easily and surely sandwiched between the tips of the pair of outer lid flaps 3a and 3b and the tongue piece 12.

The lower limit of the ratio of the width W of the tip edge of the intermediate portion 14b to the length of the easily bendable line 11b is preferably 0.8, more preferably 0.9. On the other hand, 1 is preferable as the upper limit of the above ratio. If the ratio does not reach the lower limit, the insertion piece 14 may easily come out of the insertion slot 11. On the contrary, if the ratio exceeds the upper limit, it may be difficult to insert the insertion piece 14 into the insertion slot.

With the insertion piece 14 inserted into the insertion port 11, the tip portion 14c protrudes from the insertion port 11 to the inside of the pair of outer lid flaps 3a and 3b in the width direction.

The tip portion 14c is preferably widened in the middle portion in the protruding direction. Further, it is preferable that the width of the widened portion of the tip portion 14c is larger than the length of the easily bendable line 11b. Since the tip portion 14c of the box sheet 10 is widened at the intermediate portion in the protruding direction, the state in which the insertion piece 14 is inserted into the insertion port 11 can be more reliably maintained.

(Flap outside the bottom)
The first outer flap 5a is formed in a substantially rectangular shape. The first bottom outer flap 5a has substantially the same width as the left-right length of the first side surface panel 1a. The first bottom outer flap 5a has a U-shaped recess 16a at the tip edge. The first bottom outer flap 5a has a pair of weakening lines 16b that are inclined inward in the width direction from the vicinity of both ends in the width direction at the base end edge and extend toward the tip edge side.

The second bottom outer flap 5b has substantially the same width as the left-right length of the first side surface panel 1b. The second bottom outer flap 5b has a substantially rectangular main body 17a, a projecting piece 17b protruding from the central portion of the tip edge of the main body 17a, and is inclined inward in the width direction from the vicinity of both ends in the width direction at the base end edge. It has a pair of weakening lines 17c extending toward the tip edge side.

(Flap in the bottom)
The pair of in-bottom flaps 6a and 6b are formed in a rectangular shape and substantially the same shape. The bottom flaps 6a and 6b have substantially the same width as the left-right length of the second side surface panels 2a and 2b.

In the box sheet 10, the pair of inner bottom flaps 6a and 6b are bent inward, the first outer bottom flap 5a is bent inward, and the second outer bottom flap 5b is outside the first outer bottom flap 5a. The bottom of the box body 20 can be assembled by pushing the second bottom outer flap 5b inward in the folded state. Specifically, after pushing the second bottom outer flap 5b until the projecting piece 17b of the second bottom outer flap 5b exceeds the recess 16a of the first bottom outer flap 5a, the pushing of the second bottom outer flap 5b is released. .. As a result, the reaction force of the sheet pushes the first bottom outer flap 5a and the second bottom outer flap 5b back to a position where they are substantially parallel to each other, and the first bottom outer flap 5a and the second bottom outer flap 5b are in mesh with each other. The bottom is formed with.

<Advantage>
The box sheet 10 is a box body 20 by inserting the insertion piece 14 defined in the second inner flap 4b into the insertion port 11 formed in the joint portion of the pair of outer lid flaps 3a and 3b from above. The lid can be sealed. In the box sheet 10, the insertion port 11 is defined by a U-shaped slit 11a that is convex toward the opposite side of the insertion piece 14 and an easy-to-bend line 11b that connects both ends of the slit 11a. A tongue piece 12 defined by a slit 11a and an easy-to-bend line 11b is formed at the joint portion of the pair of outer lid flaps 3a and 3b. In the box sheet 10, the insertion piece 14 can be sandwiched between the tips of the pair of outer lid flaps 3a and 3b and the tongue piece 12 in a state where the insertion piece 14 is inserted into the insertion opening 11. Therefore, according to the box sheet 10, it is easy to maintain the sealed state of the lid portion of the box body 20.

[Other embodiments]
The above embodiment does not limit the configuration of the present invention. Therefore, the above-described embodiments can be omitted, replaced or added with components of each of the above-described embodiments based on the description of the present specification and common general technical knowledge, and all of them are construed to belong to the scope of the present invention. Should be.

The insertion piece may be formed from an intermediate portion of the flap in the lid in the extending direction. Even when the insertion piece is formed from the intermediate portion of the inner flap in the extending direction, the box sheet can be inserted by, for example, reducing the width of one side of the pair of outer lid flaps. The piece can be inserted into the above insertion slot.

The insertion piece may be provided on each of the pair of in-cover flaps.

The specific shape of the insertion piece is not limited to the shape described in the above embodiment. For example, the insertion piece may not be divided into three parts, a base portion, an intermediate portion, and a tip portion. Further, the insertion piece may further have a portion other than the base portion, the intermediate portion and the tip portion.

The structure of the bottom of the box body assembled from the box sheet is not particularly limited.

As described above, the box sheet according to one aspect of the present invention can easily maintain the sealed state of the lid portion of the box body, and is therefore suitably used for storing articles and the like.

1a, 1b 1st side panel 2a, 2b 2nd side panel 3a, 3b Outer lid flap 4a 1st inner lid flap 4b 2nd inner lid flap 5a 1st outer outer flap 5b 2nd outer outer flap 6a, 6b inner bottom flap 7 Substrate 10 Box sheet 11 Insertion port 11a Slit 11b Easy-to-bend line 12 Tongue piece 13 Break line 14 Insert piece 14a Base 14b Intermediate part 14c Tip part 15 Side piece 16a Recess 16b Weakened line 17a Main body 17b Projection piece 17c Weakened line 20 Box body L1 Protruding length of the base L2 Protruding length of the middle part D1 Distance from the base end edge of the second inner flap in the plan view of the assembled state to the easy-to-bend line D2 The second lid in the plan view of the assembled state Maximum distance from the base edge of the inner flap to the slit W Width of the tip edge of the middle part

Claims (5)

A pair of first side panels and a pair of second side panels facing each other in the assembled state,
A pair of outer lid flaps extending from the upper edge of the pair of first side panel and having the tip edges abutted against each other in the assembled state.
A box sheet comprising a pair of in-cover flaps extending from the upper edge of the pair of second side panels.
On one of the flaps in the lid, a pair of breaking lines extending from the tip edge toward the base end side are formed at intervals in the width direction.
An insertion piece is defined between the pair of break lines,
An insertion port into which the insertion piece is inserted is provided at the seam portion of the pair of outer lid flaps on the side close to the insertion piece.
A box sheet in which the insertion slot is defined by a U-shaped slit that is convex toward the opposite side of the insertion piece and an easy-to-bend line connecting both ends of the slit. The box sheet according to claim 1, wherein the insertion piece is provided from the base end edge of the flap inside the lid. The insertion piece is divided into a base portion, an intermediate portion, and a tip portion from the base end side to the tip end side, and the protrusion direction length of the base portion is 1 to 3 times the sheet thickness. Yes, the length of the intermediate portion in the protruding direction is equal to or greater than the distance from the base end edge of the one inner lid flap to the easy-to-bend line in the plan view of the assembled state, and the above-mentioned is from the base end edge of the one inner lid flap. The box sheet according to claim 2, wherein the distance to the slit is equal to or less than the maximum distance. The box sheet according to claim 3, wherein the ratio of the width of the tip edge of the intermediate portion to the length of the easily bendable line is 0.8 or more and 1 or less. The box sheet according to claim 3 or 4, wherein the tip portion is widened at an intermediate portion in the protruding direction.

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