JPS62116119A - Molding process for sleeve of corrugated tube - Google Patents

Abstract

PURPOSE:To eliminate local thin-wall sections of the sleeve and mold the reinforcing rib of perfect shape by providing an opening part of the crest of the corrugated tube beforehand and filling up the crest with the resin charged into the sleeve molding space through the said opening. CONSTITUTION:When the molten resin is charged from the resin charging opening 101 into the sleeve molding space 110, the said molten resin fills up the sleeve molding space 110 to close the same, and through the opening 22, comes to the inside of the crest 22 to fill the same. At the same time, the end of corrugated tube 1 is heat fused with the molten resin, and the sleeve S is provided integrally with the end of corrugated tube 1. Also, when the concave stripe 122 for molding the reinforcing rib is formed on the core 120, the interior of the said concave stripe 122 is completely filled with the resin to form a reinforcing rib S2 of perfect shape.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for integrally equipping a corrugated pipe, which is mainly used as a drainage pipe for agricultural or civil engineering purposes, with a sleeve.

[Conventional technology]

As is well known, the outer wall of a corrugated pipe made of synthetic resin has alternating peaks and valleys. This type of corrugated pipe has thicker strength (but is relatively light) because its peaks act as reinforcing ribs.
Due to its high flexibility, it has come to be widely used as drainage pipes for agricultural or civil engineering purposes. Such corrugated tubes are usually joined using sockets, but in some cases, the end of the corrugated tube is integrally equipped with a sleeve as a socket, and the end of another corrugated tube is inserted into this sleeve. Additional additions may be required.

As a means for integrally equipping a synthetic resin circular tube with a sleeve, there is a means for expanding the diameter by pushing the end of the circular tube heated to a softening temperature into a diameter expanding jig. When applying this method as is to equip the above-mentioned corrugated pipe with a sleeve, that is, as shown in FIG.
When the corrugated tube l is provided with a sleeve S by pushing in the end of the corrugated tube 1 heated to a softening temperature to expand its diameter, a sleeve S is formed on the outer wall 2 of the corrugated tube l as shown in the figure. There is an inconvenience that the peaks 22 and troughs 21 lose their shape, making the corrugated tube l look unsightly and significantly reducing its commercial value. Therefore, it is inappropriate to employ the above-mentioned measures when equipping a corrugated tube with a sleeve.

Therefore, the present applicant previously proposed the following method as a method for preventing the mountain portion from losing its shape.

In this method, as shown in FIG. 4, the end of the corrugated pipe l is inserted into the sleeve molding space 1) 0 of the mold 100, and the ridges 22 of the outer wall 2 are raised by about two peaks into the sleeve molding space 1) 0. At the same time, the neck 121 of the core 120 is inserted into the end of the corrugated tube 1 to back up the end, and from this state, a predetermined amount of molten resin is injected into the sleeve molding space 1)0. It's a method. According to this method, the molten resin injected into the sleeve molding space 1)0 flows due to the injection pressure at that time and closes the space 1)0, and the ridge of the corrugated pipe l inserted into the space 1)0 Part 22
envelops Tanibe 21. At this time, the end of the corrugated tube 1 is heated to a softening temperature in the mold 100, and the above-mentioned injection pressure acts on the end of the corrugated tube 1 inserted into the sleeve molding space 1)0. Therefore, the peaks 22 at the ends are crushed and deformed by the molten resin and are compatible with the molten resin to be thermally fused.

When such a forming method is adopted, the peak portion 22 of the corrugated tube 1
Since the diameter of the trough portion 21 is not increased, the sleeve S can be integrally provided with the corrugated pipe without reducing the commercial value.

[Problem that the invention seeks to solve]

When molding the sleeve S using the above method, the crest 22 of the corrugated tube l is crushed into an irregular shape by the resin injected into the sleeve molding space 1)0, so that the sleeve molding space 1)0 is filled. The amount of resin required to completely block the space 1) is not constant. That is, if the degree of crushing of the peak portion 22 is large, the sleeve molding space 1)0
On the other hand, if the above-mentioned degree is small, the amount of resin required will be small. On the other hand, since the amount of resin injected into the sleeve molding space 1) 0 is determined in advance as described above, the amount of resin injected into the sleeve molding space 1) 0 depends on the degree to which the mountain portion 22 is crushed. There will be excess and deficiency. Here, there is no particular problem if the amount of resin injected into the sleeve molding space 1) 0 is a little more than the actually required amount of resin, but if it is less,
That is, if the peak portion 22 is crushed to a greater extent than initially expected, the sleeve molding space 1)0 will not be completely filled with resin. Therefore, in this case, as illustrated in FIG. 5, a local thin portion Sl may occur in the sleeve 1) 0 at a location away from the resin injection hole 101 (see FIG. 4). In addition, as shown in FIG. 4, when the core 120 is provided with grooves 122 for forming reinforcing ribs, the grooves 122 are not completely filled with resin, and as shown in FIG. In some cases, the reinforcing rib S2 may not be formed in a perfect shape on the inner surface of the sleeve S.

The present invention solves these problems by forming reinforcing ribs on the sleeve without causing deformation of the peaks provided on the outer wall of the corrugated pipe, and without creating locally thin parts on the sleeve. It is an object of the present invention to provide a method for forming a sleeve that can form the reinforcing ribs into a perfect shape.

[Means for solving problems]

In order to solve the above problems, a method for forming a sleeve of a corrugated pipe according to the present invention includes forming an opening by removing a part of the above-mentioned peaks of a corrugated pipe having an outer wall having alternating peaks and valleys. Later, by inserting this corrugated tube into the sleeve molding space of the mold, the peak portion having the opening is placed inside the sleeve molding space, and from this state, by injecting molten resin into the sleeve molding space, the sleeve is formed. The gist is that the molding space and the internal space of the peak are filled with the molten resin, thereby molding the sleeve integrally with the corrugated tube.

[Function] In the above means, if the amount of resin injected into the sleeve molding space is appropriate, the resin will completely block the sleeve molding space and will also flow through the opening of the peak located inside the sleeve molding space. It enters the mountain and completely blocks the mountain. At this time, since the ridges are not crushed by the resin, it is possible to know in advance the amount of resin required to completely close the sleeve molding space and the ridges. Therefore, it is possible to form a sleeve without locally thinned parts,
It is easily possible to form perfectly shaped reinforcing ribs on the sleeve.

〔Example〕

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

FIG. 1 shows a sleeve molding space 1 of a mold 100 for a corrugated tube 1.
)0 is shown. In the corrugated tube 1 before being inserted into the sleeve forming space 1) 0, a part of the peak 22 at the end of the outer wall 2 is broken and removed to form an annular opening 22a, and the sleeve forming space 1) is inserted into the sleeve forming space 1). Space 1)
When the corrugated tube 1 is inserted into the sleeve molding space 1), only two peaks 22 having openings 22a are located inside the sleeve molding space 1). Reference numeral 3 denotes an inner wall of the corrugated tube 1, which is heat-sealed to the inner surface of the trough 21 of the outer wall 2.

When the corrugated tube 1 is inserted into the sleeve molding space 1) 0 as described above, the neck 12 of the core 120 is inserted into the corrugated tube 1.
1 is inserted, and the end of the corrugated tube l is backed up by the neck 121.

From this state, when molten resin is injected from the resin injection hole 101 into the sleeve molding space 1)0, the molten resin fills the sleeve molding space 1)0, blocking the space 1)0, and passes through the opening 22a. It fills the inside of the mountain part 22 and blocks the inside of the mountain part 22.

At the same time, the end of the corrugated tube 1 is thermally fused with the molten resin, and the sleeve S shown in FIG. 2 is integrally provided at the end of the corrugated tube 1. In addition, the core 120 is provided with grooves 12 for forming reinforcing ribs.
2, the inside of this concave strip 122 is also completely filled with resin, and as shown in FIG. 2, a reinforcing rib S2 with a perfect shape is formed.

In the above, it is desirable that the number of ridges arranged inside the sleeve molding space 1) 0 is two or more, and if the number of ridges is less than this, thermal fusion with the molten resin injected into the sleeve molding space 1) 0 will occur. As the area becomes smaller, there are concerns about the bonding strength. Further, the opening 22a formed in the peak part 22 may be formed by cutting a part of the peak part 22 into an annular shape as described above.
The ridge portion 22 may be formed by drilling a hole or by cutting a portion of the ridge portion 22 in the circumferential direction. In short, the opening may be formed by any means and may have any shape as long as it allows the molten resin to flow into the inside of the peak portion 22.

In FIG. 2, elements corresponding to those explained in FIG. 1 are given the same reference numerals.

[Effects of the Invention] As is clear from the above description, the sleeve molding method of the present invention involves forming an opening by previously removing a portion of the peak of the corrugated tube placed inside the sleeve molding space of the mold. Since the resin injected into the sleeve molding space passes through this opening and fills the inside of the crest to close the crest, the crest is not deformed when the sleeve is molded. Therefore, when injecting a predetermined amount of resin into the sleeve molding space, the required amount of resin can be determined accurately in advance, and by injecting the predetermined amount of resin, the sleeve molding space and peaks can be filled. The inside is completely filled with the resin. Therefore, there will be no locally thin walled portions in the molded sleeve, and when molding reinforcing ribs, it is possible to reliably mold the reinforcing ribs in a perfect shape.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway side view for explaining the implementation procedure of the present invention, and FIG. 2 is a partially cutaway side view showing a corrugated tube with a sleeve manufactured by the method of the present invention. FIG. 3 is a schematic cross-sectional view for explaining a case where the method for forming a sleeve for a circular pipe is applied to a corrugated pipe, and FIGS. 4 and 5 are partially cutaway side views for explaining a comparative example. DESCRIPTION OF SYMBOLS 1... Corrugated pipe, 2... Outer wall, 21... Valley part of outer wall, 22... Peak part of outer wall, 22a... Opening, 100...
... Molding die, 1) 0... Sleeve molding space.

Claims (1)

[Claims] (1) After removing a portion of the crests of a corrugated tube having an outer wall having alternating ridges and troughs to form an opening, the corrugated tube is inserted into the sleeve molding space of the mold to A crest having an opening is placed inside the sleeve molding space, and from this state, molten resin is injected into the sleeve molding space to close the sleeve molding space and the internal space of the crest with the molten resin. A method of forming a sleeve for a corrugated pipe, in which the sleeve is formed integrally with the corrugated pipe.