JPS6250626B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a so-called metal core type hard synthetic resin-coated metal eaves gutter made of a thin steel plate coated with a hard synthetic resin.

Conventionally, as shown in FIG. 1, a metal eaves gutter body 25 having a semicircular arc cross section is coated with a soft synthetic resin 23, and ears protruding from both sides of the eaves gutter are provided on the outer surface of both upper end portions 2 of the eaves gutter body 25. A soft synthetic resin-coated metal eaves gutter having a portion 10 formed therein has been developed. The reason why the outside of the metal surface of conventional metal eaves gutters is coated with soft synthetic resin 23 is mainly for rust prevention, but since soft synthetic resin easily deforms or deteriorates, hard synthetic resin is used. There is a strong desire to develop eaves gutters covered with However, since eaves gutters are originally attached to the eaves of houses and are exposed to direct sunlight, it is not uncommon for the temperature of eaves gutters to rise to around 70 degrees Celsius in the summer. When placed in such a high-temperature environment, if a soft synthetic resin is coated on the outside of the metal eaves gutter as in the past, the soft synthetic resin will also thermally expand in accordance with the thermal expansion of the metal. Therefore, no problem arises, but when a hard synthetic resin is coated, the difference in coefficient of thermal expansion between the hard synthetic resin serving as the covering and the metal material serving as the core becomes a particular problem. For example, the linear expansion coefficient of PVC (polyvinyl chloride resin) is 7 x 0 ^-5 /℃, compared to the linear expansion coefficient of the metal material used for eaves gutters, which is about 1.1 x 10 ^-5 ℃. It is about 6 times as large. Of course, the thermal expansion in the radial direction of eaves gutters is so small that it can be completely ignored, but the thermal expansion in the longitudinal direction of eaves gutters is quite large in terms of dimensions. Because it becomes something, it becomes something that cannot be ignored. To give a specific example, if a metal eaves gutter with a length of 3.6 m is coated with hard synthetic resin as shown in Figure 1 and supported with restraints 24 at intervals of 60 cm, the temperature of the eaves gutter will be If the temperature rises above the critical temperature, Figure 8a
There is a problem in that the ears 10 become wavy as shown in FIG. This is usually called the ear wave phenomenon, but it is thought that this ear wave phenomenon occurs because the coefficient of thermal expansion of the ear part 10 of the eaves gutter and the coefficient of thermal expansion of the abdomen 20 do not match, as described later. It is being In other words, the linear expansion coefficient of a steel plate coated with a hard synthetic resin is generally given as the average of the linear expansion coefficient of the metal material serving as the core and the linear expansion coefficient of the hard synthetic resin serving as the coating. When coated as shown, the ear portion 10 has a large coefficient of thermal expansion due to the presence of a large amount of hard synthetic resin, but the abdominal portion 20 has a smaller coefficient of thermal expansion than the ear portion 10 because there is less hard synthetic resin. This is why the ear wave phenomenon occurs. The present invention has been made in view of the above-mentioned problems of the conventional example, and by minimizing the difference in the coefficient of thermal expansion between the ear part and the belly part of the eaves gutter, the so-called ear part in the above-mentioned high temperature environment can be improved. The object of the present invention is to provide a hard synthetic resin-coated metal eaves gutter that can prevent the occurrence of wave phenomena.

The structure of the present invention will be described below with reference to the illustrated embodiment. As shown in FIGS. 2 and 3, both upper ends 2 of a hard synthetic resin eaves gutter main body 1 having a semicircular arc cross section
Hollow ears 10 projecting from both sides of the eaves gutter body 1 over the entire length in the longitudinal direction are integrally formed, and the outer lower half 26 of the hollow ears 10 and the abdomen 20 of the eaves gutter body 1 are integrally formed.
Thin steel plate 12 inserted over the entire circumference of
The upper end portions 27 of both sides are folded back inside the hollow ear portion 10. In the embodiment shown in FIGS. 2a and 2b, a reinforcing rib 22 made of hard synthetic resin 5 is integrally formed in the center of the hollow ear 10, and the edge portion 28 of the thin steel plate 12 is It extends into the reinforcing rib 22. In any of the embodiments shown in FIGS. 2a to 2c, the edge portion 28 of the thin steel plate 12 is inserted inside the hollow ear portion 10, but the characteristic diagram shown in FIG. As shown in FIG.
The difference in linear expansion coefficient between the body and the abdomen 20 becomes smaller, and the critical temperature difference Δt that causes the ear wave phenomenon becomes larger. Furthermore, as shown in the embodiments of FIGS. 3a and 3b,
By bending the edge portion 28 of the thin steel plate 12 downward or upward, or by bending it in an inverted S-shape as shown in the embodiment shown in FIG. It becomes larger and stronger in terms of the degree of reinforcement. In order to manufacture such eaves gutters, as shown in FIG. 12 is heated and then introduced into a hard synthetic resin-coated mold 14. An extruder 15 is attached to the mold 14, and the resin coating is continuously applied to the surface of the thin steel plate 12. 16 is a cooling device, and mold 1
4, the eaves gutter body 1, which has been coated with high-temperature resin and heated to a high temperature, is cooled to around room temperature. The hard synthetic resin-coated eaves gutters manufactured in this way are taken up by a track-shaped take-up machine 17,
It is cut into an appropriate length by a cutting machine 18. At this time, the cutting machine 18 cuts the eaves gutter body 1 during the cutting process.
The eaves gutter body 1 can be cut without interrupting the continuous manufacturing process.

By the way, as shown in the manufacturing process of FIG. 6, when the thin steel plate 12 is roll-formed with the forming rolls 13,
However, as shown in the embodiments of FIGS. 2a to 2c of the present invention, thin-walled steel plates 12
In the case where the edge portion 28 is inserted into the hollow ear portion 10, the distortion of the edge portion 28 is less likely to appear on the surface. Additionally, stress tends to concentrate on the edge portion 28 of the thin steel plate 12,
Although there is a drawback that cracks are likely to occur from this part, in the case where the edge part 28 is protected inside the hollow ear part 10 as shown in the embodiment shown in FIGS. 2a to 2c, the edge part 28 It is difficult to apply stress to
This reduces the possibility that cracks will form in the thin steel plate 12 due to the stress.

By the way, as mentioned above, the cause of the ear wave phenomenon when the eaves gutter is placed in a high temperature environment is the buckling phenomenon caused by the difference in linear expansion coefficient between the ear part 10 and the abdomen 20 of the eaves gutter. However, the present inventors treated the eaves gutter as a pillar body with an ear part 10 and an abdomen 20 combined as shown in FIG. The most excellent ear structure was investigated by calculating the critical temperature at which the ear wave phenomenon based on the buckling phenomenon of the column occurs for 10 types of ear structures with different coefficients of linear expansion. First, when a column having a length L and a coefficient of linear expansion α thermally expands due to a temperature difference Δt, the amount of expansion λ is given by the following equation.

λ=α・Δt・L...(1) Also, the load P required to extend a column of length L by λ is given by the following formula, where E is the Young's modulus of the column and A is the cross-sectional area. is given by

P=A・E・λ/L ...(2) Furthermore, let n be the buckling mode of the column and Ei be the bending stiffness.
Then, the buckling load Pcr of the column is given by the following formula.

Pcr=n ² π ² Ei/L ² ...(3) Therefore, the following equation is derived from the three equations (1), (2), and (3) above.

Δt=n ² π ² Ei/EAαL ² ...(4) By the way, the stress in the ear 10 due to the difference in linear expansion coefficients α ₁ and α ₂ between the ear 10 and the abdomen 20 caused by the temperature difference Δt is the seventh As shown in Figure c, the linear expansion coefficient _{α e} when the expansion and contraction of the ear portion 10 and the abdomen 20 are balanced
The difference between q and the linear expansion coefficient α ₂ of the ear (α ₂ − α _e
q). That is, the seventh
Assume that the ear 10 and abdomen 20, which are in equilibrium at room temperature as shown in Figure a, expand by λ ₂ and λ ₁ , respectively, as shown in Figure 7b when the temperature rises, resulting in a difference in expansion of Δλ. Then, compressive stress S ₂ is applied to the ear portion 10 as shown in FIG. 7c, and the abdomen 2
Since equilibrium is reached when tensile stress S ₁ is applied to 0, an unreasonable stress is applied to the ear portion 10 by the amount shown by λ', and this stress is equal to the coefficient of linear expansion α at equilibrium.
It is expressed by the difference between _e q and the linear expansion coefficient α ₂ of the ear. The coefficient of linear expansion α _e q at equilibrium is given by the following equation, where the Young's moduli of the ear portion 10 and the abdomen 20 are E ₂ and E ₁ , respectively, and the cross-sectional areas are A ₂ and A ₁ , respectively.

α _e q = (E ₁ A ₁ α ₁ + E ₂ A ₂ α ₂ ) / (E ₁ A ₁ + E ₂ A ₂ ) ...(5) Therefore, the load P applied to the ear part 10 due to the temperature difference Δt ₂ is given by the following equation.

P ₂ = A ₂ E ₂ (λ ₂ - λ')/L = A ₂ E ₂ (α ₂ - α _e q)・Δt...(6) Therefore, when P ₂ becomes larger than the buckling load Pcr This causes a buckling phenomenon. The present inventors calculated the critical temperature difference Δt at which the buckling phenomenon occurs for 10 types of ear structures as shown in Figure 5 a to j, and found the most excellent ear structure. . As an example, the length of the eaves gutter is L = 3.6 m, the distance between the support points of the restraint is 60 cm, and the buckling mode order is n = 6 as shown in Figure 8a. The linear expansion coefficients of the steel plate 12 are 7×10 ^-5 /℃ and 1.1× ^{10 -5} /℃, respectively, the Young's modulus is 320Kg/mm ² and 21000Kg/mm ² , and the plate thickness is 0.86mm and 0.14mm, respectively. Figure 9 shows the results of calculating the critical temperature difference Δt at which buckling occurs for 10 types of eaves gutters that are approximately the same. As shown in the same figure, there is a structure as shown in FIGS.
It can be seen that structures such as those shown in Fig. 5 f, g, and i, in which the degree of penetration is low, are completely impractical because buckling occurs immediately with a slight temperature rise. Furthermore, as shown in FIGS. 5b and 5j, in the case where the thin steel plate 12 is inserted in the lower half of the approximately U-shaped lug 10, the critical temperature difference Δ at which the buckling phenomenon occurs is
Although t is somewhat larger, as mentioned in the explanation of the conventional example, the temperature of the eaves gutter is about 70°C, so the critical temperature difference Δt from room temperature is at least 60°C.
If the temperature is less than ℃, it cannot be said to be sufficient as eaves gutters. Compared to these, as shown in FIG. Critical temperature difference Δt is 70℃
It can be seen that the temperature has been improved to about 90°C and is sufficiently usable for practical use.

In addition, the eaves gutter is actually attached to the restraining tool 2 as shown in Figure 8a.
4, the weight of the eaves gutter acts on the eaves, which often causes a waving phenomenon with a half period as shown in Figure 8b. The order n of the buckling mode is doubled, n = 12, and therefore the critical temperature difference Δt at which buckling occurs
increases by four times in proportion to the square of n, and the critical temperature difference becomes much higher than the above calculation result. However, even in such a case, the structures shown in FIGS. 5c, d, and e are still the most excellent structures for preventing the buckling phenomenon.

Furthermore, as shown in the embodiment shown in FIGS. 3a and 3b, the edge portion 28 of the thin steel plate 12 is bent downward or upward, or bent into an inverted S-shape as shown in the embodiment shown in FIG. 3c. If this is done, the proportion of the thin steel plate 12 in the ear portion 10 will be further increased, and the strength will also be increased.

As described above, in the present invention, hollow ears protruding from both sides of the eaves gutter body over the entire length in the longitudinal direction are integrally formed at the upper ends of both sides of the eaves gutter body made of hard synthetic resin and having a semi-circular cross section. , the upper ends of both sides of the thin steel plate inserted across the outer lower half of the hollow ear and the entire circumference of the abdomen of the eaves gutter body are folded back inside the hollow ear. This has the advantage that the ratio of thin-walled steel sheets increases, and therefore the difference in coefficient of linear expansion between the ears and the abdomen becomes smaller, making it difficult for the ear wave phenomenon to occur in high-temperature environments. Since the edges are protected inside the hollow, there is an advantage that stress is less likely to be applied to the edges, and there is therefore less risk of cracking from this area. This has the advantage that the strain that occurs at the edge of a thin steel plate during roll forming is less likely to appear on the surface.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a conventional example, FIGS. 2 a, b, and c are sectional views of main parts of different embodiments of the present invention, and FIG.
Figures a, b, and c are sectional views showing other embodiments of the present invention that are modified versions of the embodiment shown in Figure 2 a, respectively. Figure 4 shows the eaves gutter shown in Figure 2 a separated into an ear part and an abdomen. Figures 5a to 5j are cross-sectional views showing the structure of the ears analyzed in the present invention, Figure 6 is a side view showing the eaves gutter manufacturing apparatus of the present invention, and Figure 7 a, b, and c are explanatory diagrams showing the expansion and contraction of the ears and abdomen of the eaves gutter, Fig. 8 a, b are plan views showing the waving phenomenon of the eaves gutter, and Fig. 9 is the subject of analysis in the present invention. It is a graph which shows the temperature characteristic of the structure of the ear part of various eaves gutter. 1 is the eaves gutter body, 2 is the upper end on both sides, 3 is the curved part,
4 is an opening surface, 5 is a hard synthetic resin, 6 and 7 are opening ends, 8 is a covering body, 9 is a connecting piece, 10 is an ear part, 11
12 is a thin steel plate, 13 is a forming roll,
14 is a mold, 15 is an extruder, 16 is a cooling device, 1
7 is a pulling machine, 18 is a cutting machine, 19 is a preheating device, 2
0 is the abdomen, 21 is an extension piece, 22 is a central reinforcing rib, 23 is a soft synthetic resin, 24 is a restraint, 25 is a main part of the eaves gutter, 26 is an outer lower half, 27 is an upper end on both sides,
28 is an edge portion.

Claims (1)

[Claims] 1 Hollow ears protruding from both sides of the eaves gutter body over the entire length in the longitudinal direction are integrally formed at the upper ends of both sides of the hard synthetic resin eaves gutter body having a semicircular arc shape in cross section, and the outside bottom of the hollow ears A metal eaves gutter coated with a hard synthetic resin, characterized in that the upper end portions of both sides of a thin steel plate inserted over the half and the entire circumference of the abdomen of the eaves gutter body are folded back inside the hollow ear portion.