JPH09262860A - Tank body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lightweight tank body becoming almost uniform in stress distribution along its peripheral direction even if external force of non-uniform pressure distribution acts especially in a case used as the tank body of a purifying tank, reduced in the deformation caused by external force and not generating the wastefulness of a material. SOLUTION: In a tank body 6 having upper and lower tanks 7, 9 constituted by the reactive injection molding of a norbornene monomer, the wall thickness of the upper tank 7 is set so as to become substantially uniform along the peripheral direction thereof and the wall thickness of the lower tank 9 is set so as to become thick on the side of the bottom part thereof as compared with the thickness in the vicinity of the connection part 8 with the upper tank 7. In the cross section of a purifying tank, when the wall thickness of the lower tank 9 within the range from the surface of the flange 8 of the lower tank 9 to an angle θ1 is set to (a) when the center of the purifying tank is set to a start point, the wall thickness of the lower tank 9 within the range from the angle θ1 to an angle θ2 is set to (b) and the wall thickness of the lower tank 9 within the range from the angle θ2 to 90 deg. is set to (c) and the wall thickness of the upper tank is set to (d), the relation of 15>=c>b>a>=3 (wherein a is 3-7mm, b is 4-10mm, c is 5-15mm, pref., 7-10mm and a>=d is 3-7mm) is formed.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a septic tank,
The present invention relates to tank bodies used for water tanks, tanks, and the like.

[0002]

2. Description of the Related Art Molding a tank body such as a septic tank with concrete or the like is complicated, requires a large amount of work, and increases costs. Also, in the FRP tank body,
Since a large pressure resistant die is expensive and the press molding method is not practical, the hand layup method of atmospheric molding is performed. However, the glass fiber powder flew during the construction, the working environment was bad, and the thickness of the tank body, particularly the corners, was likely to vary, and it was difficult to secure the mechanical strength of the tank body.

[0003]

Therefore, it has been studied to mold such a tank body with a reaction injection molded body of a norbornene-based monomer. The reaction injection molded product of norbornene-based monomer is excellent in corrosion resistance and impact resistance, and can be molded at a low pressure close to normal pressure, so that it is easy to mold using a large mold, and therefore it is suitable as a material for forming a tank body. is there.

However, in the conventional tank body composed of the reaction injection molded body, the wall thickness of the tank body is relatively thick so as to withstand the maximum load required as the tank body, The wall thickness was substantially uniform along the circumferential direction. However, forming the tank body into a thick wall is not preferable in terms of transportation and installation work because the material is wasted and the weight of the tank body increases. Although it is possible to form the tank body thinly, external force does not always act uniformly on the tank body, and in particular, the strength of the lower tank tends to be insufficient.
It was found by the present inventors.

The present invention has been made in view of the above situation, and particularly when it is used as a tank body of a septic tank, even if an external force having a non-uniform pressure distribution acts, it is substantially uniform along the circumferential direction of the tank body. Stress distribution, less deformation by external force,
Moreover, it is an object of the present invention to provide a lightweight tank body without waste of materials.

[0006]

In order to achieve the above object, the tank body according to the present invention is a tank body having an upper tank and a lower tank which are formed of a reaction injection molded product of a norbornene-based monomer. The wall thickness of the upper tank is substantially uniform along the circumferential direction, and the wall thickness of the lower tank is thicker on the bottom side compared to the wall thickness near the connection with the upper tank. It is set.

In the present invention, in the cross section of the septic tank, the center of the septic tank is the starting point, and the wall thickness of the lower tank within the range from the joining surface of the lower tank to the angle θ ₁ is a, and the angle θ is
The wall thickness of the lower tank within the range from ₁ to the angle θ ₂ is b,
When the wall thickness of the lower tank is c and the wall thickness of the upper tank is d within the range of the angle θ ₂ to 90 degrees, it is preferable that the following relationship is established.

[0008]

## EQU1 ## 15 ≧ c>b> a ≧ 3 where a = 3 to 7 mm, b = 4 to 10 mm, c = 5 to 15
mm, preferably 6 to 9 mm, and a ≧ d = 3 to 7 mm.

Further, θ ₁ is preferably 20 to 80 degrees,
It is more preferably 35 to 55 degrees, θ ₂ is preferably 20 to 90 degrees, and more preferably 55 to 85 degrees. In the cross section of the septic tank, it is preferable that the change in wall thickness of the lower tank appears symmetrically. Upper tank wall thickness d
May have a slight change in wall thickness, but is substantially uniform along the circumferential direction within a range of ± about 30%.

By setting the wall thickness within the range of the above formula, the tank body according to the present invention has a substantially uniform stress along the circumferential direction of the tank body even if an external force having a non-uniform pressure distribution acts. It has a distribution and is less deformed by external force. Therefore, it has sufficient mechanical strength as a tank body of a septic tank, for example. Further, in the present invention, by minimizing the thickness of the thickened portion, it is possible to realize a lightweight tank body with no waste of material. Furthermore, by making the thicknesses of the above-mentioned numerical relationships, the flow of the reaction stock solution in the mold is improved, unfilling at the time of molding can be prevented, and the moldability becomes good.

In the present invention, the cross-sectional shape of the body of the tank of the septic tank is such that the height of the tank in the cross-section of the body of the tank is H, the width of the tank is W, and the side wall of the tank. Radius of curvature of R
_In the case of ₁ , 1.0 ≦ R ₁ /W≦2.0 and 1.
It is preferable that 0 ≦ R ₁ /H≦2.0.

1.0> R ₁ / W or 1.0> R ₁ / H
Then, the cross-sectional shape of the body of the tank body is close to a circle. With the same width and the same height, a shape closer to a rectangular cross section has a larger cross sectional area and a larger capacity. When 2.0 <R ₁ / W or 2.0 <R ₁ / H, the cross-sectional shape of the body of the tank body becomes a shape close to a rectangular cross-section, and the capacity increases, but the mechanical strength of the tank body increases. There is a tendency to run out.

In the present invention, by molding the tank body of the septic tank from the polynorbornene resin obtained by the reaction injection molding method, the corrosion resistance and the earthquake resistance of the septic tank are improved.
Further, as compared with the FRP septic tank, the glass fiber powder does not fly during the manufacturing, the working environment is good, and the molding can be performed in a short time.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a tank body according to the present invention will be described in detail based on an embodiment shown in the drawings. 1 is a semi-transverse sectional view of a tank body of a septic tank according to an embodiment of the present invention, FIG.
3 is a schematic perspective view of a septic tank according to an embodiment of the present invention, FIG.
(A) and (B) are cross-sectional views for explaining a preferable cross-sectional shape of the body of the tank body of the septic tank, and FIG. 4 is a cross-sectional view of the main part of the joining portion between the upper tank and the lower tank.

As shown in FIGS. 1 and 2, the tank body 6 of the septic tank according to this embodiment has an upper tank 7 and a lower tank 9. Upper tank 7
The lower tank 9 and the lower tank 9 are joined by flanges 8 and 8. Details of the joint portion of the flanges 8 and 8 will be described later with reference to FIG. An inlet 10 and an outlet 11 are formed in the upper tank 7, and sewage that has flowed in from the inlet 10 is an anaerobic treatment chamber (or tank; formed by a plurality of partition plates inside the septic tank; Similarly, it is processed in a processing chamber such as an aerobic processing chamber, a precipitation chamber, or a disinfection chamber and discharged from the discharge port 11.

On the upper part of the upper tank 7, three manholes 15a, 15b, 15c are formed along the longitudinal direction of the tank. In the present embodiment, the cross-sectional shape of the body of the tank 6 is, as shown in FIG. 3A, the height of the tank in the cross-section of the body of the tank is H, and the width of the tank is When W and the radius of curvature of the side wall of the tank body is R ₁ , 1.0 ≦ R ₁ / W ≦
It is preferable that 2.0 and 1.0 ≦ R ₁ /H≦2.0.

1.0> R ₁ / W or 1.0> R ₁ / H
Then, the sectional shape of the body portion of the tank body 6 becomes close to a circle, as shown in FIG. With the same width and the same height, a shape closer to a rectangular cross section has a larger cross sectional area and a larger capacity. When 2.0 <R ₁ / W or 2.0 <R ₁ / H, the cross-sectional shape of the body of the tank body 6 becomes a shape close to a rectangular cross section, and the capacity increases, but the mechanical strength of the tank body increases. Tend to run out.

Here, the width W of the tank body 6 is 600 to 250.
0 mm, preferably 1800 to 2300 mm, and the height H of the tank body 6 is 1500 to 3000 mm, preferably 1
It is 700 to 2500 mm. W or H is 6 respectively
If it is smaller than 00 mm or 1500 mm, it cannot sufficiently meet the structural standard announced by the Ministry of Construction. on the other hand,
When W or H exceeds 2500 mm or 2000 mm, respectively, there is a problem in economical efficiency for securing strength.

The radius of curvature R ₁ of the side wall of the tank is 280
0 to 5000 mm, preferably 3200 to 4200 mm
It is. If R ₁ is less than 2800 mm, the tank cross-sectional shape is close to a circle, and if it is greater than 5000 mm, the corners of the tank have a rectangular cross-sectional shape, and the displacement of the center of the tank caused by the load on the tank becomes large. Not preferable.

The radius of curvature R ₂ of the corner of the body is preferably 350 to 600 mm, more preferably 450 to 550 mm from the viewpoint of moldability. Next, the connecting portion between the upper tank 7 and the lower tank 9 will be described with reference to FIG.

As shown in FIG. 4, the tip portion 8 of the flange 8 is
a is thicker than the base end. Moreover, the mating surface 18 of the front end portion 8a of the flange 8 is configured to project more than the mating surface 20 of the base end portion. Tip 8
Step S between the mating surface 18 of a and the mating surface 20 of the base end
Is preferably about 0.5 to 2.5 mm. The thickness t ₁ of the front end portion 8a of the flange 8, when the thickness of the base end portion of the flange 8 and the t _2, t ₂ + 2~30mm (preferably 3 to 15 mm) it is desirable that. Base end thickness t ₂
Is the thickness t ₃ of the molded body at the portion where the flange 8 is formed.
It is about the same as (the thickness of a or d described later).

At the flange 8, the mating surface 1 at the tip portion
An adhesive groove 16 and a packing groove 14 are formed between 8 and the mating surface 20 at the base end. In the adhesive groove 16,
The adhesive 12 is filled, and the packing 12 is arranged in the packing groove 14. The flanges 8 and 8 are the packing 1
It is clamped and fixed by a bolt 22 and a nut 24 at an outer position of 2. As the adhesive 26, a polyurethane adhesive, an epoxy resin adhesive, a polyacrylate adhesive, or the like can be used. As packing,
Butyl rubber, acrylonitrile-butadiene rubber, styrene-butadiene rubber, isoprene rubber, foams thereof, polyethylene foam, polypropylene polypropylene, urethane elastomer, silicone rubber, soft polyvinyl chloride (P
VC) and the like can be used.

In the present embodiment, by increasing the thickness t ₁ of the tip portion of the flange 8, the flange 8 is reinforced, and even if an external force acts on the portion of the flange 8, the portion is less likely to be damaged. . Further, by increasing the thickness t ₁ of the tip portion of the flange 8, the mating surface 18 at the tip portion does not have a wavy shape along the longitudinal direction, and the mating surface 18 can be smoothed.

Further, by providing the step S, when the flanges 8 and 8 are tightened with the bolt 22 and the nut 24, the packing 12 is conveniently crushed and the sealing property is improved. In this embodiment, the upper tank 7 and the lower tank 9 of the septic tank are made of polynorbornene-based resin obtained by a reaction injection molding method (RIM). Those formed of the resulting ring-opening polymer are preferable.

Examples of the elastomer include polybutadiene, styrene-butadiene copolymer (SBR), styrene-butadiene-styrene block copolymer (SB).
S), polyisoprene, styrene-isoprene-styrene block copolymer (SIS), ethylene-propylene-diene terpolymer (EPT) and the like.

The blending ratio of the elastomer is 1 to 20 parts by weight, preferably 2 to 15 parts by weight, based on 100 parts by weight of the norbornene-based monomer. When the blending ratio of the elastomer is low, the flexibility decreases. Conversely, if the proportion of the elastomer is too large, the glass transition temperature decreases and the strength decreases, which is not preferable.

The monomer is a cycloolefin having a norbornene ring such as dicyclopentadiene, dihydrodicyclopentadiene, tetracyclododecene and tricyclopentadiene. The metathesis catalyst is not particularly limited as long as it is a known metathesis catalyst for bulk polymerization of norbornene-based monomers such as organic ammonium molybdates such as tungsten hexachloride, tridodecyl ammonium molybdate, and tri (tridecyl) ammonium molybdate. However, organic ammonium molybdate is particularly preferred.

Examples of the activator (cocatalyst) include alkylaluminum halides such as ethylaluminum dichloride and diethylaluminum chloride, alkoxyalkylaluminum halides thereof, and organic tin compounds. As a preparation for reaction injection molding, a reaction injection molding material containing a norbornene-based monomer, a metathesis catalyst, and an activator as a main component is a liquid comprising a norbornene-based monomer and a metathesis catalyst, and the norbornene-based monomer and the activator are used. Separately into two stable liquids and separate liquids. At the time of reaction injection molding, the two liquids are mixed, then this mixed liquid is injected into the cavity of the mold, and bulk polymerization is performed in the cavity to obtain the upper tank 7 and the lower tank 9.

The mold used for the reaction injection molding is not necessarily an expensive mold having high rigidity, and is not limited to a metal mold, but may be a resin mold or a simple mold. This is because the reaction injection molding of the norbornene-based resin can be performed at a relatively low temperature and a low pressure using a low-viscosity reaction liquid. The inside of the mold is sealed with an inert gas, and the components used for the polymerization reaction are stored under an inert gas atmosphere such as nitrogen gas.
And it is preferable to operate.

The mold temperature is preferably from 10 to 150
C., more preferably 30 to 120.degree. C., still more preferably 50 to 100.degree. Mold pressure is usually 0.1-1
It is in the range of 00 kg / cm ² . The polymerization time may be appropriately selected, but is usually from 30 seconds to 2 hours after the completion of the injection of the reaction solution.
It is 0 minutes, preferably 5 minutes or less.

Since the septic tank according to this embodiment is made of polynorbornene resin obtained by the reaction injection molding method, a relatively large molded body can be easily molded. Further, the polynorbornene-based resin can have a sufficient pressure resistance required as a tank body for a septic tank by utilizing the material characteristic that the specific rigidity is low but the specific strength is high.

In the present embodiment, the tank body 6 of the septic tank as described above has a wall thickness having the following dimensional relationship. That is, as shown in FIG. 1, in the cross-section of the tank body 6 of the septic tank, with the center of the septic tank as the starting point, the lower surface within the range from the joint surface in the lower tank 9 (joint surface of the flange 8) to the angle θ _1. The wall thickness of the tank 9 is a, the wall thickness of the lower tank 9 in the range from the angle θ ₁ to the angle θ ₂ is b, and the wall thickness of the lower tank 9 in the range from the angle θ ₂ to 90 degrees. Where c is and c is the wall thickness of the upper tank 7, the following relationship is established.

[0033]

## EQU2 ## 15 ≧ c>b> a ≧ 3, where a = 3 to 7 mm, b = 4 to 10 mm, c = 5 to 15
mm, preferably 7 to 10 mm, and a ≧ d = 3 to 7 mm.

Further, θ ₁ is preferably 20 to 80 degrees,
It is more preferably 35 to 55 degrees, θ ₂ is preferably 20 to 90 degrees, and more preferably 55 to 85 degrees. In the cross section of the septic tank 6, it is preferable that the change in the wall thickness of the lower tank 9 appears symmetrically.

By setting the wall thickness within the range of the above formula, the tank body 6 according to the present embodiment can be applied to the tank body even if an external force having a non-uniform pressure distribution, for example, soil pressure in the ground acts. 6 has a substantially uniform stress distribution along the circumferential direction,
Little deformation due to external force. Therefore, for example, the tank body 6 of the septic tank has sufficient mechanical strength. In addition, in the present embodiment, the weight of the tank body 6 can be realized without waste of material by reducing the thickness of the portion to the minimum. Furthermore, by making the thicknesses of the above-mentioned numerical relationships, the flow of the reaction stock solution in the mold is improved, unfilling at the time of molding can be prevented, and the moldability becomes good.

The present invention is not limited to the above-described embodiment, but can be variously modified within the scope of the present invention. For example, the tank body according to the present invention can be suitably used not only as a tank body for a septic tank but also as a tank body buried in the ground such as an emergency water tank.

[0037]

The present invention will be described below based on more detailed examples, but the present invention is not limited to these examples. Example 1 Upper tank 7 of tank body 6 of the septic tank shown in FIGS. 1, 2, 3 (A) and 4
The lower tank 9 and the lower tank 9 were molded by reaction injection molding.

In reaction injection molding, 85% of dicyclopentadiene (DCP) and 15% of asymmetrical cyclopentadiene trimer were used, and styrene-isoprene-
Styrene block copolymer (Kraton 1170, manufactured by Shell Co.) was dissolved in 5% and phenolic antioxidant Irganox 1010 (manufactured by Ciba Geigy Co., Ltd.) was dissolved in 2%. Diethyl aluminum chloride (DEAC) was added to the monomer so that the concentration was 40 mmol, n-propanol was 44 mmol, and silicon tetrachloride was 20 mmol (A).
liquid). On the other hand, tri (tridecyl) ammonium molybdate was added to the monomer at a concentration of 10 mmol (Solution B).

The liquids A and B thus prepared were sent to a power mixer with a gear pump so that the volume ratio was 1: 1 and then, the mold temperature was 70 ° C. in the mold. And the injection pressure was 2.0 Kg / cm ² or less. The reaction was carried out for 3 minutes in the mold, and a series of these operations was performed in a nitrogen atmosphere.

Then, the molded body was taken out from the mold to obtain an upper tank 7 and a lower tank 9. The width W of the tank body 6 shown in FIG.
Was 1300 mm, the height H was 1730 mm, the corner radius of curvature R ₂ was 500 mm, and the body side radius of curvature R ₁ was 4500 mm. Further, the wall thickness t ₁ of the tip portion 8a of the flange 8 shown in FIG. 4 was 6 mm, and the wall thickness t ₂ of the base end portion was about 9 mm. The step S of the second mating surface 20 with respect to the first mating surface 18 was 2 mm. An O-ring made of butyl rubber and having a diameter of 8 mm was used as the packing 12, and a butyl rubber adhesive was used as an adhesive for joining the flanges 8 and 8.

The wall thickness d of the upper tank 7 shown in FIG. 1 was 5 mm and was constant in the circumferential direction. In the lower tank 9, θ ₁ = 50 from the horizontal plane
In the range up to degrees, the wall thickness a = 6 mm, and θ ₁ to θ ₂
The thickness b gradually changed from 6 mm to 8 mm in the range up to 70 °, and the thickness c = 8 mm in the range from θ ₂ to 90 °.

Inlet 10 and outlet of the tank body 6 of this septic tank
11 and manholes 15a, 15b, 15c are covered,
The top of the tank (manhole position) is 1630 from the liquid surface
The tank body 6 is submerged in water so that
When the large displacement was examined, the position A of the tank body shown in FIG. 1 was about 2
A displacement of up to 28 mm was observed at the 5 degree angular position. This
The stress received at the position is analyzed by the finite element method.
B, 1.1 kgf / mm ^Two Was small. In addition, stress
Is the largest part of C at 2.4kgf / m
m^Two However, the displacement was as small as 8 mm. In this example
The weight of the tank body (upper tank + lower tank) was 127 Kg.

Comparative Example 1 The same septic tank as in Example 1 except that the upper tank has a uniform wall thickness of 5 mm along the circumferential direction and the lower tank has a uniform wall thickness of 7 mm along the circumferential direction. When a tank body (upper tank + lower tank) was formed and the maximum displacement in water was examined in the same manner as in Example 1, it was 31 mm at the position C. When analyzed by the finite element method, the stress received at this position is the maximum and 3.3
It was as large as kgf / mm ² . The stress received at the position A was 0.93 kgf / mm ² which was not much different from that in Example 1.

The weight of this tank body (upper tank + lower tank) is 130.
Kg. By comparing Evaluation Example 1 and Comparative Example 1, the maximum stress can be reduced in the tank body according to Example 1 of the present invention as compared with the tank body according to Comparative Example 1 having substantially the same weight. Was confirmed. This means that the weight of the tank body can be reduced in the present invention under the condition that the maximum stress is the same.

[0045]

As described above, the tank body according to the present invention can be operated even if an external force having a non-uniform pressure distribution acts.
The stress distribution is substantially uniform along the circumferential direction of the tank body, and deformation by external force is small. Therefore, it has sufficient mechanical strength as a tank body of a septic tank, for example. In the present invention,
By minimizing the thickened portion, it is possible to realize a lightweight tank body without wasting material.

[Brief description of drawings]

FIG. 1 is a semi-transverse sectional view of a tank body of a septic tank according to an embodiment of the present invention.

FIG. 2 is a schematic perspective view of a septic tank according to an embodiment of the present invention.

FIG. 3A and FIG. 3B are cross-sectional views for explaining a preferable cross-sectional shape of a body of a tank body of a septic tank.

FIG. 4 is a cross-sectional view of a main part of a joint portion between an upper tank and a lower tank.

[Explanation of symbols]

 6 ... Tank body 7 ... Upper tank 8 ... Flange 9 ... Lower tank

Claims (1)

[Claims] 1. A tank body having an upper tank and a lower tank which are formed of a reaction injection molded product of a norbornene-based monomer, wherein the thickness of the upper tank is substantially uniform along the circumferential direction. The wall thickness of the lower tank is compared with the wall thickness near the connection with the upper tank.
A tank body set to be thicker on the bottom side.