JPH081577U - Plastic file or case - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a plastic file or case in which deterioration of the appearance of a file due to springback, whitening or tearing due to bending, and wavy deformation on both sides of the fold line are suppressed. [Structure] It is composed of two main triangular grooves with an inverted triangular cross section and an auxiliary groove formed on the surface opposite to this main groove at a position corresponding to the main groove, and the following conditions are satisfied. A plastic file or case formed by bending a plastic sheet having a crease line formed thereon along the crease line. [Conditions] C <5t, 0.1t ≦ d <D ≦ 0.8t (where C is the interval between the main grooves, D is the depth of the main grooves, d is the depth of the auxiliary grooves, and t is plastic). Indicates the thickness of the sheet)

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a plastic file or a case formed by folding a fold line plastic sheet at the fold line, and more specifically, to the plastic file or case having good shape retention when folded at the fold line. It is about the case.

[0002]

[Prior art]

 2. Description of the Related Art Conventionally, as a box-shaped case for accommodating files for binding documents and VTR tapes, a plastic sheet formed by bending at a predetermined location has been used. When the plastic sheet is bent to make a file or the like, a crease line consisting of a single groove is formed in advance on the plastic sheet so that the plastic sheet can be easily and accurately folded.

[0003]

[Problems to be solved by the device]

 However, the plastic file and the like formed from the plastic sheet having the single fold line as described above have the following problems. (1) When bent or stretched, the elasticity of the plastic sheet causes the plastic sheet to return, and the plastic sheet does not finish at a certain angle, so-called springback deteriorates the appearance of the obtained file or the like. (2) Due to the above springback, it becomes difficult to assemble a plastic case by an automatic assembly machine. (3) Since the plastic sheet in the groove portion is largely deformed during bending, whitening is likely to occur. (4) Partial stress is likely to occur, and due to the effect, both sides of the crease line are apt to be wavy, especially when a thin plastic sheet is used. (5) The fold lines may deteriorate and break due to bending and stretching accompanying the opening and closing of the file.

In order to improve the drawback of a plastic file in which the crease line is formed of a single groove, a plastic sheet having a crease line of two grooves is used. Is also proposed.

In the case of forming the crease line formed by the two groove lines, the springback is small and the appearance of the file is deteriorated as compared with the case where the fold line formed by the one groove line is formed. The problem is solved to some extent. However, it was difficult to say that the improvement of the spring back property was sufficient only by forming the crease line consisting of the two grooves.

When the cross-sectional shape of the groove is an inverted trapezoid or a U-shape having a bottom width of 30% or more of the thickness of the plastic sheet, the crease is formed by bending and unfolding accompanying opening and closing of the file. The wire deteriorates and is easy to tear.

The present invention has improved these drawbacks of conventional plastic files and the like, and deteriorated the appearance of files and the like due to springback, whitening of the bent portion, wavy deformation on both sides of the crease line due to partial stress, It provides a plastic file or case that prevents deterioration of the crease line part due to bending and stretching accompanying opening and closing of the file.

[0008]

[Means for Solving the Problems]

 According to the present invention, in a plastic file or case formed by folding a plastic sheet with a crease line along the crease line, the crease line is formed by two main stripe grooves having an inverted triangular cross section and a side opposite to the main stripe groove. It is composed of an auxiliary groove formed on the surface at a position corresponding to the main groove, and the distance C between each main groove, the depth D of the main groove, the depth d of the auxiliary groove, and the depth of the plastic sheet. It is characterized in that the thickness t satisfies the condition shown in Formula 2.

## EQU2 ## C <5t 0.1t ≦ d <D ≦ 0.8t

In addition, in the plastic file or case of the present invention, it is preferable that the bottom of each main groove has a curved surface with a curvature.

[0010]

【Example】

 An embodiment of the plastic file of the present invention will be described below with reference to the drawings. FIG. 1 is a front view of the plastic file of the present invention before it is bent, and FIG. 2 is an enlarged cross-sectional view taken along the line A-A 'in FIG. Further, in the figure, reference numeral 1 is a plastic sheet, reference numeral 2 is a fold line, reference numerals 3 and 4 are main grooves, and reference numerals 6 and 7 are auxiliary grooves.

The plastic file of the present invention is formed by bending the plastic sheet 1 shown in FIGS. 1 and 2 along a fold line 2. In the case of a plastic case, a plastic sheet punched into a predetermined shape and having a crease line formed at a predetermined position is bent along the crease line as described above, and the folded pieces that are folded and overlapped with each other are not overlapped. It is assembled by joining by means such as sonic fusion.

The above plastic sheet 1 is a polyolefin resin such as polypropylene, propylene-vinyl acetate copolymer, ethylene-propylene copolymer, blend of polyethylene and polypropylene, blend of α-olefin and polypropylene, etc. It is made of plastics such as polystyrene, polystyrene and polyvinyl chloride resin. Polypropylene is particularly preferable as the plastic. The plastic sheet 1 may be hard, semi-rigid, or soft, and is appropriately selected according to the application. The plastic sheet 1 may be foamed or non-foamed.

The fold line 2 is composed of main stripe grooves 3 and 4 having an inverted triangular cross section and auxiliary stripe grooves 6 and 7 formed on the side surface opposite to the surface on which the main stripe grooves 3 and 4 are formed. ing.

The main ridge grooves 3 and 4 forming the fold line 2 are parallel to each other, and the distance C between the main ridge grooves 3 and 4 is within 5 times the thickness t of the plastic sheet 1. Are formed so close together. If the intervals between the main grooves 3 and 4 are too large, not only is the crease thicker by the distance between the main grooves, which is unsightly, but also only one of the main grooves is greatly bent, giving a uniform appearance. There is a problem that it is not possible.

When the plastic sheet 1 is folded at the crease line portion having the two main ridge grooves 3 and 4, the amount of deformation of each ridge groove is greater than when the fold line composed of only one ridge groove is folded. Whitening and wavy deformation on both sides of the crease line are reduced, but if the shape of the groove is an inverted trapezoid or U-shape with a bottom width of 30% or more of the thickness of the plastic sheet, the file opening Due to bending and stretching due to closing, the crease lines are likely to break. Also, the pressure when forming the above-mentioned inverted trapezoidal or U-shaped groove must be greater than the pressure when forming an inverted triangular groove with a cross-sectional shape. There is also the problem that the wear of the blade becomes faster. In consideration of the above points, in the present invention, the cross-sectional shape of the main groove 3 and 4 is an inverted triangular shape as shown in FIG.

As shown in FIG. 3, the main grooves 3, 4 of the present invention may have a bottom portion having a curved surface having a curvature. If the bottom portions 5 of the inverted triangular grooves 3 and 4 are formed by curved surfaces having a curvature, breakage of the crease line portion due to bending and stretching due to opening and closing of the file is extremely reduced.

As shown in FIG. 2, the auxiliary groove grooves 6 and 7 formed on the surface opposite to the surface on which the main groove grooves 3 and 4 are formed correspond to the bottom portions of the main groove grooves 3 and 4, respectively. It is formed so that the bottom is located. By forming the auxiliary grooves 6 and 7, the springback is reduced, and the amount of deformation due to bending is reduced, so that whitening is unlikely to occur and deformation on both sides of the fold line is extremely small. Become. The cross-sectional shape of the auxiliary groove may be any shape. That is, the shape is not limited to the inverted triangular shape shown in FIG. 2, and may be, for example, an arc shape.

The relationship between the depths D of the main grooves 3 and 4 described above, the depth d of the auxiliary grooves 6 and 7 and the thickness t of the plastic sheet may satisfy the condition shown in the following expression 3. is necessary.

## EQU3 ## 0.1t ≦ d <D ≦ 0.8t

If the residual thickness s of the plastic sheet at the locations where the main groove and the auxiliary groove are formed is too small, the crease line portion is easily broken by bending and stretching. Therefore, the residual thickness s of the plastic sheet is preferably 0.2 t or more. That is, it is desirable to determine the depths D of the main grooves 3 and 4 and the depths d of the auxiliary grooves 6 and 7 so as to satisfy the conditions of the above formula 3 and the following formula 4.

## EQU00004 ## 0.2t <(d + D) .ltoreq.0.8t

[0020]

[Effect of device]

 As described above, the plastic file or case of the present invention comprises two main stripe grooves having an inverted triangular cross section and an auxiliary stripe formed on the surface opposite to the main stripe groove at a position corresponding to the main stripe groove. The plastic sheet is formed by bending the fold line that composes a crease line that satisfies the specific conditions and is formed by bending the groove. It also has the effect that it is unlikely to be torn or torn, and that even if a thin plastic sheet is used, wavy deformation is unlikely to occur on both sides of the fold line. Therefore, it is durable and can be used for a long period of time, and its appearance does not change for a long period of time, and it is particularly suitable for frequent opening and closing. In addition, when the bottom of the main groove is formed of a curved surface having a curvature, breakage of the crease line portion due to bending and stretching accompanying opening and closing of the file is further reduced.

[Brief description of drawings]

FIG. 1 is a front view showing an example of a plastic file of the present invention.

FIG. 2 is an enlarged cross-sectional view taken along the line A-A ′ of FIG.

FIG. 3 is an enlarged cross-sectional view showing another example of a groove for forming a fold line.

[Explanation of symbols]

 1 ... Plastic sheet 2 ... Crease line 3, 4 ... Main groove 5 ... Bottom of main groove 6, 7 ... Auxiliary groove

Claims (2)

[Scope of utility model registration request] 1. A plastic file or case formed by folding a plastic sheet with crease lines along the crease lines, wherein each crease line has two main grooves and a surface on which the main grooves are formed. It consists of two auxiliary grooves formed on the opposite side, each main groove has an inverted triangular cross-sectional shape, and each auxiliary groove has a bottom portion corresponding to the bottom of each main groove. It is characterized in that the interval C of each main groove, the depth D of the main groove, the depth d of the auxiliary groove, and the thickness t of the plastic sheet satisfy the condition shown in Formula 1. Plastic file or case. ## EQU1 ## C <5t 0.1t ≦ d <D ≦ 0.8t 2. The plastic file or case according to claim 1, wherein the bottom of each main groove is formed of a curved surface having a curvature.