JPH0153172B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a synthetic resin cylinder, which forms a square cylinder by bending and bonding a synthetic resin sheet into a square shape. In order to manufacture a rectangular cylindrical body by folding a synthetic resin sheet, it is common to provide the sheet with bending lines in advance.

However, while it is necessary to make the creases deep in order to improve the bendability, it is also necessary to make the creases as shallow as possible in order to improve the shape retention of the cylindrical body after bending, and it is necessary to fully satisfy both characteristics. is quite difficult.

The present invention solves this difficulty by eliminating the once-formed ruled grooves after bending, thereby achieving both bendability and shape retention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An example of implementing the present invention will be described below with reference to the drawings. Figure 1 is a cross-sectional view of a synthetic resin sheet with ruled lines, Figures 2 to 7 are cross-sectional views showing the process of bending and gluing the sheet to form a cylinder, and Figure 8 is a square cylinder. FIG. 9 is a front view of the manufacturing apparatus, and FIG. 10 is a plan view thereof.

The figure shows an example of forming a square tube, in which a thermoplastic synthetic resin sheet, such as a single or composite sheet S of polyvinyl chloride, polycarbonate, polystyrene, polypropylene, polyester, etc.
This is carried out as shown in Figs. 1 to 8 using . The device is illustrated in FIGS. 9 and 10, and the sheet S
is fed out from the sheet roll 1 and processed.

First, the sheet S is provided with groove-shaped ruled lines L ₁ , L ₂ , L ₃ , and L _{4 that define the margin A and the face plates B, C, D, and E, which are square tubes, as shown in FIG} . The ruled lines are formed by pressing the ruled line roll 2 against the sheet surface at a temperature below the softening temperature of the sheet S to form grooves having a V-shaped cross section or a U-shaped cross section. Its depth is 30 to 70% of the thickness of sheet S
is desirable. Since these ruled lines are formed at low temperatures, they have the property of returning to their original flat state when heated.

Next, each is bent from the above-mentioned ruled lines to form a rectangular tube. In this embodiment, first, the margin A is between the acute-angled guide portion 3' of the guide plate 3 and the groove 4' of the groove wheel 4, as shown in FIG. Bend it into an acute angle along ruled line _L1 . And face plates B, C, D, and E that become square tubes
is bent along the surface of the profile 5. For example, face plate C,
D is lined with folding rolls 6 and 7 as shown in Figure 3.
Bend it 90 degrees with L ₃ and press it on both sides of the shape material 5. Then, as shown in Fig.
Bending 90 degrees at L ₄ to form face plates C, D, and E into a U-shape, and then bending face plate B by about 90 degrees at ruled line L ₂ using a bending roll 9 as shown in Fig. 5. C, D, E
Make it into a square cylinder.

Note that the adhesive margin A may be bent when the face plate is bent as shown in FIG. 3 or 4.

Next, as shown in FIG. 6, the gluing margin A is raised by more than 90 degrees with the raising plate 10 and placed on the face plate E, adhesive is applied with the adhesive nozzle 11, and the face plate B is placed on the roll 12 as shown in FIG. is pressed against the mold material 5, the adhesive margin A is overlapped with the face plate E, and the adhesive is pressed with the roll 13 to bond it to the face plate E. In this example, since the margin A was raised from an acute angle, it tends to return to the bent state due to elasticity and press against the face plate E. Therefore, no force is exerted in the direction away from the face plate E, and therefore no pressure is applied. Although it will adhere by itself without it, if it is pressed by the roll 13, the adhesion will be even better.

The rectangular cylinder formed by bending and adhering in this way is heated to a temperature higher than the softening temperature of the sheet S using hot air, heated rolls, or other suitable heat source Q to restore the shape of the bent part and shape it. , this shaped rectangular cylinder is taken up by a conveyor 14.

When a sheet is bent along a ruled line as described above, the ruled line forms a V-shaped gap G on the inside of the folded part as shown in Figure 8, and the thickness of the sheet is thin in some parts, so the strength of the sheet as it is is poor. However, when this is heated to a temperature higher than the softening temperature of the sheet S, the above-mentioned gap G is restored to the state before the formation of the recess and becomes full. As shown in the figure, since the bent part K is at right angles with no gaps, its strength is restored, making it stiffer and preventing it from losing its shape.It also has the advantage that the whitening of objects that have turned white when folded will disappear. .

The present invention forms a cylindrical body by bending a synthetic resin sheet along ruled lines as described above, and by heating the sheet to a temperature higher than the softening temperature of the sheet, the gap between the folded parts is restored and filled, thereby restoring its strength. Since it is possible to strengthen the cylinder body and prevent it from deforming, a durable cylinder with excellent dimensional accuracy and excellent quality can be obtained.

[Brief explanation of drawings]

The drawings show an example of carrying out the present invention, and Fig. 1 is a cross-sectional view of a synthetic resin sheet provided with ruled lines, and Figs. 2 to 7 show the process of bending and gluing the sheet to form a cylinder. 8 is an enlarged cross-sectional view showing the bent portion of the rectangular tube, FIG. 9 is a front view of the manufacturing apparatus, and FIG. 10 is a plan view. S is synthetic resin sheet, A is adhesive margin, B, C,
D and E are face plates, L ₁ , L ₂ , L ₃ and L ₄ are ruled lines, Q is a heat source, 1 is a sheet roll, 2 is a ruled line roll, 3 is a guide plate, 4 is a groove wheel, 5 is a profile material, 6, 7, 8, and 9 are rolls for folding, 10 is a raising plate, 11 is an adhesive nozzle, 12, 13 are rolls, and 14 is a conveyor.

Claims (1)

[Claims] 1. A synthetic resin sheet is heated and pressed at a temperature lower than the softening temperature of the sheet to form a groove-like indentation, and the sheet is bent along the ruled lines. A method for manufacturing a synthetic resin cylindrical body, characterized in that, after forming the cylindrical body, the ruled line portion is heated to a temperature higher than the softening temperature of the sheet to increase the recessed gap in the ruled line portion.