JPH0747484Y2 - Plastic U-shaped groove - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a U-shaped groove (or trough, trough, hereinafter simply referred to as U-shaped groove) used for civil engineering and electrical work, etc. By forming an integrally molded product of a thermoplastic resin having a structure, it is possible to provide an unprecedented lightweight product that is easy to handle and inexpensive.

[Prior Art] U-shaped grooves, which have been used in the fields of civil engineering, construction, electrical work, and agriculture, are mainly used for water passages and conduits for wires and electric wires. Therefore, it can be said that it is an indispensable member in the above fields.

However, such a U-shaped groove is generally composed of a main body A and a lid B which can be said to be substantially U-shaped as shown in FIG. The type without is also used. Materials for such U-shaped grooves include wood, metal, and concrete, but wood products have difficulty in decay and durability, so they are required only for temporary installation in a very short period of time.

On the other hand, metal products are expensive and extremely heavy, and because they corrode, they are used only in parts that require durability, and the main material in this field is concrete products. . These concrete U-shaped grooves are made by pouring fresh concrete into a metal frame or a wooden frame, defoaming it, and then removing it from the frame after a certain training period, but a thickness of several cm is required in terms of strength. And As a result, it is extremely heavy.

Further, some reinforcing bars are included for the purpose of reinforcement, but they are heavier. Generally, these are laid to a required length by connecting those of a certain length. By the way, looking at their weight, it is 25 cm in the U-shaped groove used as a conduit for electric wires.
It can be seen that some of them have a length of up to 1 m, and some are up to 100 kg from inside and outside of 10 kg, and are extremely heavy. For road gutters, the weight will be further increased by increasing the strength and reinforcing the reinforcing bars.

However, it cannot be said that these U-shaped grooves are satisfactory. In other words, it is the evidence that many chips and cracks are found.

However, the biggest drawback is that it is heavy. In other words, it can be said that these laying construction sites are not in a scaffolding environment where safety is adequately secured, but rather in extremely unstable places.
Accidents in these constructions due to human power cannot be tolerated. Moreover, the feature of this accident is that it is not a minor cut such as a cut.

On the other hand, most of these U-shaped grooves are laid in a place where weeds grow, so that during the weeding work, an accident may occur due to the damage of the hook, the saw or the like, or the occasional blade of the cut fly. It also has drawbacks.

On the other hand, it has been pointed out that there are many accidents when replacing damaged items, but one of the reasons is that there is not enough handles.
Of course, a handle with a handle as shown in Fig. 2 is also introduced, but it is omitted because the cost at the time of manufacturing the U-shaped groove will increase unless the handle is sticking out from the outer wall surface. Is. There are also attempts to overcome such drawbacks.
That is, although it is plasticization, I hear that injection molding has been canceled because it is unavoidable that defects such as gate cracks and stress cracks and mold investment become large and extremely expensive. On the other hand, although a method using profile extrusion was also investigated, it was eventually applied only to rain gutters.

That is, there are currently no plastic products in the U-shaped groove.

[Problems to be Solved by the Invention] The present invention aims to reduce the weight by providing a double wall structure by blow molding of thermoplastics, and an integral structure in which the main body and the lid are connected by a hinge portion or Body,
The purpose of the present invention is to obtain an inexpensive U-shaped groove which is independent of the lid and is lightweight and excellent in durability.

[Means for Solving the Problems] In order to finish lighter than concrete, if the specific gravity of concrete is less than about 2.3, even plastic products of the same shape can be made lighter. However, it is difficult to obtain a processing technique in which the thickness of each part is about 20 to 40 mm and the cross section of the short side is almost U-shaped, and the lid can be integrally formed. Injection molding is the easiest to think of, but it is very expensive as mentioned above. As a result of their efforts, the present inventors came to the present invention by paying attention to a so-called double wall (double wall) blow molding technique, for example, a method as disclosed in JP-A-60-67130.

That is, a drastic weight reduction can be achieved by providing a space between the plastic walls as shown in FIG. 3. If necessary, a recess as shown in FIG. 4 is formed instead of projecting the handle to the outer surface. It is possible to make it possible, the mold which is a drawback of the injection molding can be obtained at a low cost of 1/2 to 1/6, and the U-shaped groove for connecting the U-shaped groove can be freely set as shown in FIG. Mounting points, water drain holes can be made at a stretch during molding (see Fig. 6), reinforcing ribs as shown in Fig. 7 can be driven in at the time of molding, and protection for electric wires when immersed in water as shown in Fig. 8. As a measure, the protrusion can be made at a stretch at the time of molding, the main body and the lid can be integrally formed (Fig. 9), a hinge that can withstand frequent opening and closing of the main body and the lid can be given, and shape retention in the space, For the purpose of adjusting rigidity and weight, injection of foaming resin and filling with sand, water, etc. It is excellent At a point where I can. That is, it is also possible to make up for a defect that is too light. For the filling of the foamable resin, for example, the injection filling of polyurethane may use the air injection hole formed at the time of molding, but when it is insufficient in terms of the hole diameter, it may be increased by a separate drill etc.,
The holes can be blocked by heat-sealing a sheet of the same material prepared separately. Thus, the target structure of the present invention can be obtained.

Thermoplastics such as polyethylene and polypropylene can be used as the plastic for obtaining such a structural portion, and among them, polyethylene is suitable because of its excellent moldability and electric insulation in terms of electric accident countermeasures when used as conduits for electric wires. There is.

However, any plastic may be used in the present invention, and pigments, antioxidants, ultraviolet absorbers, fillers, etc. for the purpose of modification may also be used.

[Example] A circular parison was extruded at a resin temperature of 230 to 250 ° C. with an extruder (screw diameter: 115 mmφ), a die diameter: 400 mmφ, using a high density polyethylene having an MFR of 0.03 and a density of 0.960.
With the split structure die described in 67130, the length shown in FIG. 9 is 1 m,
Outside height 18 cm, outside width 15 cm, thickness of each part is 3 mm (breakdown polyethylene outer wall 0.3 cm, middle part 2.4 cm, inner wall 0.3 cm) and convex lid 4.5 m thick to fit with 1 m length (breakdown Polyethylene upper wall 0.3 cm, middle part 3.9 cm, polyethylene lower wall 0.3 cm)
The U-shaped groove was molded. The blowing air pressure at this time is about 5 kgf / c
At m ² , the total molding time was 4 minutes.

The parison control was 20 points. 0.1g to this
The total weight of foamed polyurethane filled with / cm ² of foamable polyurethane is 5.7 kg, and the same size of concrete is 31 kg for the main body and 13.5 kg for the lid, which is a total of 44.5 kg. It weighs only about 1/8.

[Effect of the invention] The U-shaped groove according to the present invention is extremely light and durable,
There is no decay (corrosion), and even if one worker carries out the laying work, there is no fear of an accident at all.

[Brief description of drawings]

Fig. 1 is a cross-sectional view of a conventional concrete U-shaped groove, (1 is a main body, 2 is a lid.) Fig. 2 is a cross-sectional view of a conventional concrete U-shaped groove with a handle, and Fig. 3 is a book. FIG. 4 is a cross-sectional view of the U-shaped groove according to the present invention, (3 is a plastic wall, 4 is a space portion). FIG.
(5 shows a handle) FIG. 5 is a top view of an engaging concave and convex portion for connecting U-shaped grooves according to the present invention, (6 is a convex portion for engaging, 7 is a concave portion for engaging) FIG. 6 is a book 6-2 shows a U-shaped drainage hole according to the invention, 6-2 is a
7 is a sectional view of a U-shaped groove according to the present invention, 7-2 is a sectional view of a, and 9 is a reinforcing rib. FIG. 8 is according to the present invention. With a U-shaped grooved water immersion prevention rack, 8-1 shows a vertical cross section, 8-2 shows a cross-sectional view,
(10 shows a water immersion prevention rack) FIG. 9 is a perspective view of a U-shaped groove according to the present invention, in which a main body lid is integrally formed, and 9-2 is a sectional view of a, showing the engagement of the main body and the lid. (11 shows a hinge part) FIG. 10 is a cross-sectional view of a U-shaped groove according to the present invention, showing the mating of the body lid being independent.

Claims (2)

[Scope of utility model registration request] 1. A plastic U-shaped groove in which a main body having a double wall structure and a lid are independently integrally molded of a thermoplastic resin. 2. A U-shaped groove made of plastic integrally formed of a thermoplastic resin, which is an integral structure in which a main body having a double wall structure and a lid are connected by a hinge portion.