JPH0721221A - Optimum thickness design method for gutter - Google Patents

Abstract

PURPOSE:To provide an established optimum thickness design method for a twist, the extension of a diameter and bending owing to the full of water. CONSTITUTION:A method is to design the optimum thickness of a gutter by dividing a molded goods shape model being a continuous product in a deformed section shape in an analyzing shape moded of fine element and deformation- analyzing the gutter in various shapes by using a limited element method. When a maximum value in the allowable range of the deformation of the gutter is set to be a deformation reference value, the plural kinds of thicknesses are set, the arbitrary place of the molded goods shape model is fixed and a prescribed load is given. Thus, displaced amounts at that time are obtained for the respective thicknesses, an approximate curve (shown by a solid line) is generated based on the displaced amounts for the obtained thicknesses and a crossing point P1 between the approximated curve and a horizontal line (shown by a broken line) passing a deformation reference value is decided as the optimum thickness.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention divides a molded product shape model, which is a continuous product of atypical cross-sectional shape, into analysis shape models of minute elements, and performs deformation analysis of rain gutters of various shapes using the finite element method. The present invention thus relates to a method for designing an optimum wall thickness of a rain gutter.

[0002]

2. Description of the Related Art When designing a continuous product having an irregular cross-sectional shape having an opening, design items include twisting performance, diameter expansion performance, flexure performance and the like.

The twisting performance is an important index showing the strength of the product, and if the twisting performance is inferior, the reliability of the product is impaired. Here, the twist angle in the twist performance refers to the twist angle θ11 of the free end 52 when the one end 51 of the rain gutter is pointed or fixed, as shown in FIG.

The diameter expansion performance is an item indicating the ease with which a rain gutter can be opened. Not only the characteristics of rigidity, but also the rain gutter is dropped from the eaves due to the opening of the rain gutter and deformation due to snowfall. It is also a substitute characteristic for items such as "do". Here, the diameter expansion of the rain gutter indicates the ease of opening when the both ears 611, 612 of the one end 61 of the rain gutter are pushed outward (indicated by arrows in the figure), as shown in FIG. Therefore, the diameter expansion analysis of rain gutter is to analyze how much the ears deform (open) with a constant load (opening load to open both ears of the rain gutter by hand). Say that.

The flexure performance referred to here is the flexure performance of the eaves gutter when the eaves gutter is full, and is the deformation of the eaves gutter when the eaves gutter is full of water, especially the flexure of the bottom wall. is there. Deflection of the bottom wall of the eaves gutter not only has a problem in appearance, but also causes a pool of water and reduces drainage performance. In addition, when the amount of deflection of the bottom wall increases, a gap is created between the rain gutter and the components (joint, stop, etc.) to which the gutter is joined, and water leaks.

As described above, each of the above items is an important item to be considered in designing, but conventionally, product design for each such item is empirically or by a structural analysis or the like, displacement relative to a set wall thickness. I just wanted the amount.

That is, in the conventional product design, the wall thickness design procedure for twisting, the wall thickness designing procedure for expanding diameter, and the wall thickness designing procedure for full water deflection are not established as a series of flow, respectively, which is rational. The design was not done.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an optimum designing method of the established wall thickness for each of twist, diameter expansion, and full-deflection.

[0009]

In order to solve the above problems, the method for designing the optimum thickness of a rain gutter according to the present invention is to convert a molded product shape model, which is a continuous product of irregular cross-sectional shape, into an analysis shape model of minute elements. It is a method of designing the optimum wall thickness of the rain gutter by dividing and performing deformation analysis of the rain gutter of various shapes using the finite element method. When setting a reference value, a plurality of types of wall thicknesses are set, and a fixed load is applied by fixing any location of the molded product shape model, and the displacement amount at that time is obtained for each wall thickness. An approximate curve is created based on the calculated displacement amount for each wall thickness, and a certain range including the intersection of this approximate curve and the deformation reference value is determined as the optimum wall thickness.

[0010]

The maximum value of the allowable range of deformation of the rain gutter is set as the deformation reference value. For example, in the case of twisting performance, the twisting angle of 35 degrees is set as the deformation reference value, in the case of diameter expansion performance (easiness to open), 30 mm is set as the deformation reference value, and in the case of bending performance, 1 mm is set as the deformation reference value. To do.

After that, a plurality of types (for example, five types) of wall thicknesses are set as the wall thicknesses of the molded product shape model to be analyzed,
The FEM structural analysis is performed for each thickness, and the displacement amount for each thickness is calculated. That is, for the twisting performance, the twisting angle in the two directions of X and Y at the bottom of the free end is calculated, for the diameter expansion performance, the diameter expansion amount of the eaves gutter end is calculated, and for the deflection performance, the bottom wall of the eaves gutter is calculated. Calculate the amount of deflection of the part.

Then, an approximate curve is created based on the amount of deformation for each wall thickness thus obtained, and a certain range including the intersection of this approximate curve and the deformation reference value is determined as the optimum wall thickness. In principle, the intersection of the approximate curve and the deformation reference value is determined as the optimum wall thickness, but considering the wall thickness variation due to molding, for example, when there is a wall thickness variation of ± 10% in molding, The value obtained by multiplying the wall thickness value obtained at the intersection by 1.1 is determined as the optimum wall thickness.

As a result, it is possible to design a product having an optimum wall thickness, including variations in the wall thickness.

[0014]

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

FIG. 1 shows an example of the shape of a rain gutter to which the method for designing the optimum thickness of the rain gutter according to the present invention is applied.

That is, a gutter body 4 having a bottom wall portion 1, a front wall portion 2 and a rear wall portion 3 and having a substantially U-shaped cross section, and each of the front wall portion 2 and the rear wall portion 3 of the gutter body 4. A front ear portion 5 and a rear ear portion 6 formed along the front edge, and a hollow rib 7 formed substantially parallel to the front ear portion 5 at a position slightly lower than the middle of the front wall portion 2. Is formed by. Then, the inclination angle of the front wall portion 2 with respect to the bottom wall portion 1 is formed slightly more gently than the inclination angle of the rear wall portion 3 with respect to the bottom wall portion 1, and the front wall portion 2 is higher than the rear wall portion 3. The formed cross-sectional shape is atypical.

Next, as specific examples of the optimum wall thickness designing method for the rain gutter having the above-mentioned structure, (1) optimum wall thickness designing method for twisting performance, (2) optimum wall thickness designing method for diameter expansion performance, (3) Each of the optimum wall thickness designing methods for the full-deflection deflection performance will be described below.

(1) Optimum wall thickness design method for twisting performance First, a twisting angle of 35 degrees is set as the maximum value (deformation reference value) of the allowable range of twisting performance of a rain gutter. Further, as the wall thickness (t) of the molded product shape model to be analyzed, 0.8,
Five types of 0.9, 1.0, 1.1 and 1.2 (mm) are set.

Then, for each wall thickness (t), the FEM
Structural analysis is performed to calculate the displacement amount for each wall thickness (t). That is, for the twist analysis, the twist angles in the two directions of X and Y at the bottom of the free end are calculated.

That is, as shown in FIG. 2, the bottom wall portion 1 of the gutter body 4 is placed vertically, and the front wall portion 2 is turned up to create a model. Then, all the nodes of the cross section at one end 8 are completely constrained (the model element of this embodiment is a 20-node solid), and a constant load is applied to the other end 9. In this embodiment, gravity is set as the load to be applied. That is, the twist angle θ1 due to its own weight is calculated.

The twist angle θ1 for each wall thickness thus obtained is plotted on the graph shown in FIG. 3 to obtain an approximate curve (a regression curve by the method of least squares or a curve approximated by a hyperbola: shown by a solid line). To create. In the graph shown in FIG. 3, the vertical axis represents the twist angle and the horizontal axis represents the wall thickness (mm). Then, a horizontal line (shown by a broken line) passing through the twist angle of 35 degrees set as the deformation reference value is drawn on this graph, and the wall thickness (t) indicated by the intersection P1 between this horizontal line and the approximate curve is set as the optimum wall thickness. decide. In the case of this embodiment, the optimum wall thickness for the twisting performance is shown in FIG.
It is about 0.88 (mm).

In consideration of variations in wall thickness due to molding, for example, when there is a wall thickness variation of ± 10% in molding, the wall thickness value obtained from the intersection P1 (0.
88) is multiplied by 1.1 to determine 0.97 (mm) as the optimum wall thickness.

As a result, it is possible to design a product having an optimum wall thickness including variations in wall thickness.

(2) Optimum wall thickness design method for diameter expansion performance First, 30 mm (1 kg load in the horizontal direction) is set as the maximum value (deformation reference value) of the allowable range of the diameter expansion performance of the rain gutter.
Further, as the wall thickness (t) of the molded product shape model to be analyzed, five types of 0.9, 1.0, 1.2, 1.3, 1.4 (mm) are set.

Then, for each wall thickness (t), FEM
Structural analysis is performed to calculate the amount of diameter expansion for each wall thickness (t).

That is, as shown in FIG. 4, the ear portion 6 of the rear wall portion 3 at one end portion of the gutter body 4 is fixed to the ear portion 5 of the front wall portion 2 facing the ear portion 6 and the horizontal direction is 1 kg. Load W
By multiplying by, the diameter expansion amount L1 (see FIG. 5) is calculated.

The diameter expansion amount L1 for each wall thickness thus obtained is plotted on the graph shown in FIG. 6, and an approximate curve (a regression curve by the method of least squares or a curve approximated by a hyperbola: a solid line is shown. ) Is created. In the graph shown in FIG. 5, the vertical axis represents the diameter expansion amount (mm) and the horizontal axis represents the wall thickness (mm). Then, a horizontal line (shown by a broken line) passing through the expanded diameter 30 mm set as the deformation reference value is drawn on this graph, and the wall thickness (t) indicated by the intersection P2 between this horizontal line and the approximate curve is determined as the optimum wall thickness. To do.

In the case of this embodiment, the optimum wall thickness for the diameter expansion performance is about 0.97 (mm) from FIG.

In consideration of variations in wall thickness due to molding, for example, when there is a wall thickness variation of ± 10% in molding, the wall thickness value obtained from the intersection P2 (0.
The optimum thickness is determined to be 1.07 (mm) obtained by multiplying 97 mm) by 1.1.

As a result, it is possible to design a product with an optimum wall thickness that includes variations in wall thickness.

(3) Optimum wall thickness design method for full water deflection performance First, 1 mm is set as the maximum value (deformation reference value) of the permissible range for full water deflection performance of a rain gutter. Further, as the wall thickness (t) of the molded article shape model to be analyzed, 0.9, 1.0,
Five types of 1.2, 1.3 and 1.4 (mm) are set.

Then, the FEM is calculated for each wall thickness (t).
Structural analysis is performed to calculate the amount of deflection of the bottom wall portion for each wall thickness (t).

That is, as shown in FIG. 7, a gutter support (including joint) 10 fixed to the eaves at intervals of 500 mm.
The gutter body 4 is supported and fixed to the gutter body 4, and the gutter body 4 is filled with water (state of hydrostatic pressure with water filled up to the upper part of the rear ear part 6)
Maximum deflection part (the lowermost position of the curved part shown by the broken line) 11
The maximum deflection amount L2 of is calculated.

That is, the density ρ = 1.0 × 10 ^-6 Kg / m
³ and g = 9.8 m / s ² , the gutter body 4
The pressure p at the water depth h of

[0035]

## EQU1 ## It is given so that p = ρgh. In addition, the constraint condition is given to the symmetry plane with the portions (front ear 5 and rear ear 6) where the gutter body 4 and the gutter support 10 are in contact with each other. In other words, the front ear contact part is completely restrained, and the rear ear contact part is forcedly displaced horizontally by 1 mm (however,
(Completely restrained in the vertical direction).

The maximum deflection amount L2 for each wall thickness obtained under the above conditions is plotted on the graph shown in FIG. 8 to obtain an approximate curve (regression curve by the method of least squares or a curve approximated by a hyperbola: shown by a solid line). To create. In the graph shown in FIG. 8, the vertical axis represents the amount of full-deflection (mm) and the horizontal axis represents the wall thickness (mm).
Has become. Then, on this graph, a horizontal line (shown by a broken line) passing through the full-deflection amount of 1 mm set as the deformation reference value is drawn, and the intersection P3 between this horizontal line and the approximate curve
The wall thickness (t) indicated by is determined as the optimum wall thickness.

In the case of this embodiment, the optimum wall thickness for the flexure performance under full water is about 0.92 (mm) from FIG.

In consideration of variations in wall thickness due to molding, for example, when there is a wall thickness variation of ± 10% in molding, the wall thickness value obtained from the intersection P3 (0.
The optimum thickness is determined as 1.01 (mm) by multiplying 92 mm) by 1.1.

As a result, it is possible to design a product having an optimum wall thickness including variations in wall thickness.

[0040]

The optimum thickness designing method for rain gutters according to the present invention is performed by setting a plurality of types of thicknesses, fixing an arbitrary part of the molded product shape model and applying a constant load at that time. The displacement amount of each thickness is calculated, an approximate curve is created based on the calculated displacement amount for each thickness, and a certain range including the intersection of this approximate curve and the deformation reference value is determined as the optimum thickness. Since this is done, changes in various displacement amounts (twist angle, diameter expansion amount, deflection amount, etc.) with respect to the wall thickness can be known, so that more accurate design is possible.

[Brief description of drawings]

FIG. 1 is a side view showing an example of the shape of a rain gutter to which an optimum wall thickness designing method for a rain gutter according to the present invention is applied.

FIG. 2 is a diagram illustrating a method of analyzing a twist angle.

FIG. 3 is a graph showing the relationship between the twist angle and the optimum wall thickness.

FIG. 4 is a diagram illustrating a method of analyzing a diameter expansion amount.

FIG. 5 is a diagram illustrating a method of analyzing a diameter expansion amount.

FIG. 6 is a graph showing the relationship between the amount of diameter expansion and the optimum wall thickness.

FIG. 7 is a diagram illustrating a method of analyzing the amount of full water deflection.

FIG. 8 is a graph showing the relationship between the amount of full water deflection and the optimum wall thickness.

FIG. 9 is a diagram illustrating a twist angle in twist performance.

FIG. 10 is a diagram illustrating a method for expanding the diameter of a rain gutter.

[Explanation of symbols]

 1 bottom wall 2 front wall 3 rear wall 4 eaves gutter body 8, 9 end

Claims (1)

[Claims] 1. A rain gutter is obtained by dividing a molded product shape model, which is a continuous product of atypical cross-sectional shape, into an analysis shape model of minute elements and performing deformation analysis of rain gutters of various shapes using the finite element method. A method of designing an optimum wall thickness, wherein when the maximum value of the allowable range of deformation of the rain gutter is set as a deformation reference value, a plurality of kinds of wall thicknesses are set, and any portion of the molded product shape model is set. By fixing and applying a constant load, the displacement at that time is calculated for each wall thickness,
An optimum curve of the rain gutter characterized by creating an approximate curve based on the calculated displacement amount for each wall thickness, and determining a certain range including the intersection of the approximate curve and the deformation reference value as the optimum wall thickness. Thickness design method.