JPS6158625B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rain gutter, and more specifically, to an improvement of an arc-shaped rain gutter. This relates to a rain gutter in which a sheet-like body 2 having a small coefficient is buried toward the inner side of the neutral axis of bending of the rain gutter body 1 over substantially the entire circumference of the rain gutter body 1.

Generally, a rain gutter formed in an arc shape from a thermoplastic synthetic resin is thermally deformed in the direction in which the arc expands when exposed to direct sunlight in summer, as shown in FIGS. 1a and 1b. In other words, since the arc-shaped rain gutter is deformed in a weak direction when bent in a direction perpendicular to the axis of the rain gutter, its bending strength is weakened, and when it is softened by heating, the rain gutter is also deformed. I had an easy problem.

The present invention was devised in view of the above-mentioned drawbacks of the prior art, and includes a sheet-like material having a smaller coefficient of expansion than the thermoplastic synthetic resin used to form the gutter body, which is made of a sheet-like material having a smaller coefficient of expansion than the neutral axis of bending of the gutter body. By burying the rain gutter over almost the entire circumference of the gutter body with one side toward the inner surface, the arc-shaped rain gutter heats and deforms when exposed to direct sunlight in the summer. It is possible to cause heating deformation in the direction in which the curvature of the arc of the arc-shaped rain gutter becomes smaller, that is, in the direction in which the bending strength improves, making it possible to increase the bending strength compared to conventional ones. By using a metal plate as the core material, it is possible to increase the mechanical strength such as impact resistance of the rain gutter, and even when heated, the rain gutter body made of thermoplastic synthetic resin retains its strength. It is an object of the present invention to provide a rain gutter that can suppress so-called dripping and, as a result, significantly improve the strength of a synthetic resin rain gutter when it is deformed by heat.

Embodiments of the present invention will be described in detail below with reference to illustrative drawings.

A metal plate 3 made of a thin iron plate as an example of the sheet-like body 2 is bent into an arc shape using a jig (not shown), and then the arc-shaped metal plate 3 is passed through a die 4. Inside, the periphery of the metal plate 3 is coated with a thermoplastic synthetic resin such as polyvinyl chloride, and the gutter body 1 made of thermoplastic synthetic resin is coated with the metal plate 3 whose expansion coefficient is smaller than that of the thermoplastic synthetic resin. It is buried to form rain gutters.
As shown in FIG. 4, the metal plate 3 is buried in a position offset toward the inner surface of the rain gutter body 1 made of thermoplastic synthetic resin with respect to the neutral axis of bending (the stress-free line). Therefore, the thickness t ₁ of the resin layer on the inner surface of the metal plate 3 is much thinner than the thickness t ₂ of the resin layer on the outer surface. However, when the arc-shaped rain gutter is exposed to direct sunlight in the summer, the resin layer on the outer side of the metal plate 3 on the inner side of the neutral axis of bending will thermally expand to a large extent. As shown in Figures a and b, the rain gutter is heated and deformed in the direction in which the curvature of the circular arc becomes smaller, that is, in the direction in which the bending strength is improved.
Therefore, the bending strength can be increased compared to the conventional case where the bending strength is heated and deformed in a direction in which the bending strength decreases. Moreover, the metal plate 3 serves as a core material and can increase the mechanical strength such as impact resistance of the rain gutter.

As described above, the present invention has a sheet-like material having a smaller expansion coefficient than the thermoplastic synthetic resin used to form the rain gutter body, which is biased toward the inner side of the neutral axis of bending of the rain gutter body, so that substantially the entire rain gutter body can be completely bent. Because it is buried all around the circumference, when the arc-shaped rain gutter is exposed to direct sunlight in the summer, the gutter will bend in the direction where the curvature of the arc of the arc-shaped rain gutter becomes smaller, that is, the bending strength will be improved. It can be heated and deformed in the direction of bending, and the bending strength can be increased compared to conventional ones. That is, there is an advantage that the effect of increasing the bending strength of the sheet-like body can be effectively increased by shifting the sheet-like body toward the inner side of the rain gutter body relative to the neutral bending axis. Furthermore, if a metal plate is used as the sheet-like body having a small coefficient of expansion, mechanical strength such as impact resistance of the rain gutter can be increased by using this metal plate as a core material. Furthermore, even when the rain gutter is heated and deformed, the metal plate acts as a core material and can suppress the so-called sagging of the thermoplastic synthetic resin rain gutter body, and as a whole, the strength of the synthetic resin rain gutter against heat deformation can be significantly improved. I've reached it.

[Brief explanation of the drawing]

Figures 1a and b are schematic side views of the conventional example before and after modification, Figure 2 is a side view of the manufacturing apparatus of the present invention, Figure 3 is a side view of the same rain gutter, and Figure 4 is a side view of the same as above. A in figure 3
FIGS. 5a and 5b are schematic side views of the same before and after the deformation. 1 is the rain gutter main body, 2 is a sheet-like body, and 3 is a metal plate.

Claims (1)

[Scope of Claims] 1. A rain gutter body made of thermoplastic synthetic resin is formed into an arc shape, and a sheet-like material having a smaller expansion coefficient than the thermoplastic synthetic resin is placed on the inner side of the gutter body with respect to its neutral axis of bending. A rain gutter that is offset and buried around the entire circumference of the gutter body. 2. The rain gutter according to claim 1, wherein the sheet-like body having a small coefficient of expansion is a metal plate.