JPH059923U - Plastic sheet with fold lines - Google Patents

Abstract

(57) [Abstract] [Purpose] Assemble a container with high dimensional accuracy and little twist. [Structure] A fold line 2 formed on a plastic sheet 1 is formed by three parallel grooves 3a, 3b, 3c.
The two groove grooves 3a and 3c on both sides are V-shaped. Center groove 3
b is made into a square shape so that the square groove 3b can be surely bent, and the bending amount is dispersed by the three groove grooves 3a, 3b and 3c to reduce the springback and prevent whitening and breakage.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a plastic sheet having a fold line.

[0002]

[Prior Art]

 It has been customary to assemble a container by punching a non-foamed hard plastic sheet made of polyvinyl chloride, polypropylene or the like into a predetermined shape, at the same time making a crease line, and folding along the crease line.

As a plastic sheet with a crease line, one in which the crease line has a single groove and one having two parallel grooves (see Japanese Utility Model Publication No. 61-39544) are conventionally known. There is.

[0004]

[Problems to be solved by the device]

 By the way, in a plastic sheet with a single groove as a crease line, when bent along the crease line, the thin wall thickness at the bottom of the groove greatly expands, springback causes a return, and it does not finish at a certain angle. There is a problem that it is difficult to assemble containers automatically.

Further, since the thin thick portion of the groove bottom is largely deformed by bending, there is a disadvantage that whitening is likely to occur and the thin thick portion is easily broken.

On the other hand, in a plastic sheet having two parallel grooves as crease lines, since the bending amount is dispersed in each groove portion, the above inconvenience can be solved, but The problem arises.

That is, since the groove is usually formed by pressing the grooved blade, it is difficult to form the two grooves with a uniform depth over the entire length, and the groove between the two grooves is difficult to form. The bending angle of the two grooves may be different due to the difference in depth, which causes a problem that a container with high dimensional accuracy cannot be obtained.

In addition, during bending, the bending position may shift from one groove to the other groove, and the container is twisted due to the change in the bending position, and the longer the container, the greater the tendency and the better the appearance. There is a problem that the container cannot be obtained.

This invention solves the above problems, improves the dimensional accuracy of a container assembled by folding a plastic sheet with crease lines, and makes it possible to assemble a container with little twist. It is an issue.

[0010]

[Means for Solving the Problems]

 In order to solve the above problems, in the present invention, the fold line formed on the plastic sheet has three grooves, the two grooves on both sides have a V shape, and the central groove has a rectangular shape. The groove width of the opening of the rectangular groove is made substantially equal to the groove width of the opening of the V-shaped groove.

[0011]

[Action]

 With the above configuration, the bending amount can be dispersed by the three grooves when the plastic sheet is bent, and the bending can be performed without causing whitening or tearing.

Further, since the central groove is rectangular, the thin-walled portion at the bottom of the rectangular groove is easier to bend than the thin-walled portion at the bottom of the V-shaped groove, and the thin wall portion of the rectangular groove is It can be bent with a high degree of accuracy because it can be subjected to much of the bending.

[0013]

【Example】

 An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows a development view of a container made of a plastic sheet 1. The plastic sheet 1 has a plurality of fold lines 2, and a container is formed by folding the plastic sheet 1 along each fold line 2.

Here, the plastic sheet 1 is made of a non-foaming hard plastic sheet such as polyvinyl chloride, polypropylene, or polystyrene.

FIG. 2 shows details of the fold line 2 formed on the plastic sheet 1. This fold line 2 consists of three parallel grooves 3a, 3b, 3c, and the grooves 3a, 3c on both sides are V-shaped (including U-shaped), while the central groove 3b is It is supposed to be prismatic. The groove width W ₁ of the opening of the rectangular groove 3b is substantially equal to the groove width W ₂ of the opening of the V-shaped groove 3a, 3b. Here, if the distance between the three groove grooves 3a, 3b, 3c is too large, when the sheet 1 is folded along the fold line 2 by 180 °, the thickness of the bent portion becomes large, and the sheet 1 is When assembled in a folded or flat tubular shape and stacked on top of each other, the thickness of both sides is greater than the thickness of the center, and stable stacking cannot be obtained.

Therefore, it is preferable to reduce the distance between the three groove grooves 3a, 3b, 3c.

Further, if both ends of the three grooves 3a, 3b, 3c reach the outer peripheral edge 4 of the plastic sheet 1, the outer peripheral edge 4 is at the intersection of each groove 3a, 3b, 3c. Since the wall thickness is thin, both ends of each groove 3a, 3b, 3c are easily broken when the plastic sheet 1 is bent along the fold line 2. Therefore, the grooves 3a, 3b, 3c preferably have a length such that a small interval is formed between both ends of the groove 3a, 3b, 3c.

As described above, the fold line 2 formed on the plastic sheet 1 is formed by the three parallel slits 3a, 3b, 3c, so that the plastic sheet 1 is rotated by 90 ° along the fold line 2. When bent, the amount of bending is dispersed by the grooves 3a, 3b, 3c as shown in FIG. 3. Therefore, the amount of deformation of the thin and thick part at the bottom of each groove 3a, 3b, 3c should be reduced. You can Therefore, the return angle due to springback is small, and there is no inconvenience of whitening or tearing.

Further, among the three groove grooves 3a, 3b, 3c, the two groove grooves 3a, 3c on both sides are V-shaped, and the central groove groove 3b is rectangular, so that the bottom portion of the rectangular groove groove 3b is formed. The thin-walled portion 5 of the V-shaped grooves 3a and 3c is more easily bent than the thin-walled portion 6 at the bottom of the V-shaped grooves 3a and 3c. Most of the bending can be received by the thin thick portion 5.

Therefore, when the container is formed by bending the plastic sheet 1, it is possible to assemble a uniform container having a high dimensional accuracy, a small twist, and a good appearance.

The V-shaped grooves 3a and 3c and the rectangular groove 3b may have the same groove depth. As illustrated, the rectangular groove 3b is slightly smaller than the V-shaped grooves 3a and 3c. May be deep. When the rectangular groove 3b is deep, the plastic sheet 1 can be bent more effectively.

FIG. 4 shows an example of an apparatus for forming the fold line 2. This forming apparatus attaches a sheet punching blade 11 and three grooving blades 12, 13, and 14 which are superposed on each other to a die board 10, and the die board 10 is provided on a lower surface of a lift board 15 provided so as to be vertically movable. The sheet punching blade 11 and the grooving blades 12, 13 and 14 are pressed against the plastic sheet 1 placed on the base 16 and the groove 3a is punched at the same time. 3b and 3c are formed.

When forming the grooves 3a, 3b, 3c as described above, if the grooving blades 12, 13, 14 are heated to a temperature at which the plastic sheet 1 is not melted, a small pressing force is applied to the grooves. 3a, 3b, 3c can be formed.

[0024]

As described above, in the plastic sheet with crease lines according to the present invention, since the bending amount can be dispersed in each of the three grooves, the thin and thick portion at the bottom of each groove can be distributed. It is possible to obtain a container with a small amount of elongation, preventing whitening and breakage of the bent portion, and having a soft feel with rounded corners.

Further, among the three grooves, the two grooves on both sides are V-shaped and the central groove is rectangular, so that when the crease line is bent, the thin-walled portion of the rectangular groove is surely secured. Can be folded into Therefore, it is possible to fold with high accuracy and to assemble a container with high dimensional accuracy and little twist.

[Brief description of drawings]

FIG. 1 is a development view of a plastic sheet according to the present invention.

FIG. 2 is a sectional view taken along line II-II in FIG.

FIG. 3 is a cross-sectional view of a folded state along a fold line

FIG. 4 is a sectional view showing an example of a crease line forming device.

[Explanation of symbols]

 1 plastic sheet 2 fold line 3a, 3b, 3c groove

Claims (1)

[Claims for utility model registration] [Claim 1] In a plastic sheet with crease lines, the crease lines are made up of three parallel grooves, two grooves on both sides are V-shaped, and a central groove is formed. Is a polygon, and the groove width of the opening of the rectangular groove is substantially equal to the groove width of the opening of the V-shaped groove.