JPH025171Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a synthetic resin pipe that can be used as a drainage pipe such as a main sewer pipe, and particularly to a pipe manufactured by continuous injection molding.

(Prior Art) A long pipe manufactured by continuous injection molding of synthetic resin such as vinyl chloride has conventionally had an inner circumferential surface 1 having a large number of tapered surfaces with the same slope, as shown in Fig. 6. Consisting of 11 sets, each tapered surface 11
were continuous through the stepped portion 2. As is clear from FIG. 7, the stepped portion 2 was formed over the entire circumference of the inner circumferential surface 1. This is because the conventional pipe A is manufactured by injecting synthetic resin into a molding space between an outer mold and an inner mold that are arranged concentrically, and the slope of the tapered surface 11 is This is due to the draft angle required for mold release given to the inner mold.

On the other hand, drainage pipes such as main sewer pipes must be constructed with a predetermined flow gradient to ensure smooth water flow. Although this flow gradient α depends on the diameter of the pipe, it is generally set to about 0.8/1000 to 3/1000. However, the draft angle of the inner mold, that is, the slope β of the tapered surface 11 is 2.6/100.
(1.5 degrees). Therefore, α<β, and if the conventional pipe A is constructed with a slope equivalent to the flow slope α above in order to be used as the main sewer pipe, water and foreign matter will accumulate at the bottom of the pipe between the stepped portions 2 and 2. This causes an inconvenience. In order to avoid this, it is possible to construct pipe A with a slope greater than α + β, but if this is done, pipe A will be too sloped and it will be impossible to use it as the main pipe of the sewer, which is not realistic. .

(Problems to be solved by the invention) This invention solves the problem that conventional pipes manufactured by continuous injection molding are not suitable for use as drainage pipes such as main sewer pipes for the above reasons. The purpose is to provide a pipe that can be manufactured by continuous injection molding without causing any problems as a drainage pipe if it is constructed with a flow gradient of about 0.8/1000 to 3/1000 as described above. In other words, the present invention provides a drainage pipe such as a sewer main pipe that can be manufactured by continuous injection molding.

(Means for Solving the Problems) In order to solve the above problems, the pipe according to the present invention has an inner circumferential surface consisting of a set of many tapered surfaces, and these tapered surfaces are flat at one point in the circumferential direction. The gist is that the area is continuous with the area and is continuous with the other parts via step portions.

(Function) According to the above method, if a flat surface with many continuous tapered surfaces is constructed as the pipe bottom, it can be used as a drainage pipe by simply providing a flow gradient of about 0.8/1000 to 3/1000. It can be used suitably. It is also possible to manufacture by continuous injection molding.

(Example) The pipe A illustrated in FIG. Second
As is clear from the figure, these tapered surfaces 1
1 is continuous in a flat manner at one point in the circumferential direction to form a flat surface 12, and is continued at other points via a stepped portion 2. That is, the axis X of each tapered surface 11 is inclined at an angle γ with respect to the axis O of the pipe A, and the axes X of each tapered surface 11 are set parallel to each other with a constant interval maintained. Furthermore, the above inclination angle γ is the same as that of the tapered surface 11 of the pipe A relative to the flat surface 12.
is set to half of the inclination angle δ.

According to such a pipe A, the tapered surface 11
If the pipe is constructed so that the flat surface 12, which is the part A that is continuous with the flat, becomes the pipe bottom, and the slope of this pipe bottom is set to about 0.8/1000 to 3/1000, smooth water flow can be achieved. The flow gradient α required to ensure
is ensured. That is, since the tube bottom is flat, the gradient of the tube bottom becomes the flow gradient α, and in the above case, α=0.8/1000 to 3/1000. Therefore, the pipe A constructed in this manner can be used as a drainage pipe.

Next, the case where the pipe A is manufactured by continuous injection molding will be explained.

In this case, as shown in FIG.
The axis of the inner mold 6 is made to coincide with the axis O of the pipe A to be manufactured, whereas the axis of the inner mold 6 is inclined at an angle γ with respect to the axis O of the pipe A.
The pushing and pulling direction is determined in the axial direction of the inner mold 6 indicated by arrow P, that is, in the axial center X direction of the tapered surface 11. In this way, the pipe A explained in FIGS. 1 and 2 can be easily manufactured by continuous injection molding. In addition, in FIG. 3, the inner mold 6 that has been pulled out during mold release is shown by imaginary lines. Further, in FIG. 3, the inclination angle δ explained in FIG. 1 is added.

By the way, there are cases where a pipe with ribs is used as a strong drainage pipe buried in a place under a large load such as under a road, and the pipe is required to ensure a smooth flow of water. However, since ribbed pipes have conventionally been manufactured by continuous injection molding, the above requirements have not been fully met for the reasons explained at the beginning. Therefore, like the pipe A shown in FIG. 4, the inner circumferential surface 1 of the pipe A, which is reinforced by providing annular ribs 7 at a plurality of locations at predetermined pitches, has a structure similar to that in FIG. 1. can be particularly beneficial. That is, by doing so, a strong pipe A that can ensure smooth water flow can be easily manufactured by continuous injection molding. In this case, as clearly shown in FIG. 5, if the outer edge of the rib 7 is made flat in the part corresponding to the part A (flat surface 12) which is continuous with the flat part of the tapered surface 11, the flat surface can be flattened. There is an advantage that the flat surface 12 becomes the pipe bottom simply by placing the portion 71 at the bottom of the groove for laying the pipe. There is also the advantage that the trouble of the pipe A rolling during construction and making the position of the flat surface 12 unclear is eliminated.

(Effects of the invention) As is clear from the above, according to the invention, it is possible to provide a pipe suitable for use as a drainage pipe such as the main pipe of a sewer system even by continuous injection molding. It is now possible to use the attached pipe as a drainage pipe, which has a great practical effect.

[Brief explanation of the drawing]

FIG. 1 is a vertical sectional side view showing a pipe according to an embodiment of the present invention, FIG. 2 is a sectional view taken along the - line in FIG. 5 is a sectional view taken along the line - in FIG. 4, FIG. 6 is a longitudinal sectional side view showing a conventional pipe manufactured by continuous injection molding, and FIG. The diagram is in Figure 6-
It is a sectional view along a line. A... Pipe, 1... Inner peripheral surface of the pipe, 11...
...Tapered surface, 12...Flat surface, 2...Stepped portion, A...Point continuous to the flat of tapered surface.

Claims (1)

[Scope of utility model registration request] A product made of synthetic resin whose inner circumferential surface is composed of a set of a large number of tapered surfaces, and these tapered surfaces are continuous in a flat manner at one point in the circumferential direction and are continuous at other points via stepped portions. pipe.