JPH0221477B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a double-walled pipe used as a drain pipe, etc., and a method for manufacturing the same.

Double-walled pipes, in which a cylindrical inner wall is heat-sealed to the inner surface of a reinforcing outer wall that has alternating annular peaks and valleys, have excellent earth pressure resistance, so they can be used underground like drainage pipes. It may be used by being buried inside.

Conventionally, this type of double-walled pipe was manufactured by extruding a synthetic resin for forming the outer wall from an extruder onto the uneven molding surface of a pair of half-split molds facing each other at a constant speed while running in synchrony with each other at a constant speed. A molten resin outer layer having peaks and valleys is continuously molded, and a synthetic resin for forming an inner wall is extruded from an extruder into a cylindrical shape onto the inner surface of the valleys of the outer layer. The molten resin inner layer was formed by heat-sealing the molded product, and the molded product thus obtained was released from the mold after curing, and then cut into pieces of predetermined size and separated.

Therefore, when connecting double-walled pipes on-site, each connecting end of the two double-walled pipes is inserted into a separately prepared connecting joint. However, this method requires a separate connection joint, the work of connecting double-walled pipes is cumbersome, and there are disadvantages in appearance as the connection joint protrudes from the outer periphery of the joint. Ta.

The present invention was made in order to improve the drawbacks of the conventional art, and its purpose is to eliminate the need for the conventionally required connection joints, to make the connection work easier and faster, and to make the connecting parts The object of the present invention is to propose a double-walled pipe having a good appearance and substantially the same shape as the other parts, and an effective method for manufacturing the same.

That is, the double-walled tube according to the present invention has an inlet at one end,
Each of the double-walled pipes has a socket at the other end, and the method for manufacturing a double-walled pipe according to the present invention is characterized in that a part of the above-mentioned conventional mold is provided with a socket molding surface and a socket molding surface of a predetermined shape. A molten resin layer for forming an outer wall and a molten resin layer for forming an inner wall are sequentially injected onto the molding surfaces under predetermined pressure conditions, and the part corresponding to the insertion hole in the obtained molded product is It is cut and separated at a predetermined position so that the socket equivalent part is held at both ends.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The double-walled pipe and method for manufacturing the same according to the present invention will be explained below with reference to the drawings.

FIG. 1 shows a double-walled tube 1 according to the invention. That is, the double wall tube 1 has a cylindrical inner wall 2 made of synthetic resin and an outer wall 3 made of synthetic resin surrounding the outer periphery, and has an insertion port 4 at one end and a socket 5 at the other end. ing. The outer wall 3 has the above-mentioned insertion port 4.
Annular peaks 3a and valleys 3 over the entire length excluding
b are provided alternately, and these peak portions 3a and valley portions 3b improve the pressure resistance. In addition, the inner wall 2 has a uniform inner diameter except for the socket 5, and overlaps the inner surface of the valley 3b of the outer wall 3 and the entire length of the inner surface of the outer wall 3 of the socket 4, so that they are thermally fused to each other. worn and integrated. Further, the inner diameter of the socket 5 is configured to be the same or almost the same as the outer diameter of the socket 4.

When connecting such a double wall pipe 1, please refer to Fig. 2a.
Two double-walled pipes 1, 1 connected to each other as in
After the socket 5 and the socket 4 are butted together, the socket 4 is inserted into the socket 5 as shown in Figure b. At this time, an adhesive or a sealant is applied between the insertion port 4 and the socket 5 as necessary to ensure watertightness between the two.

When the double-walled pipes 1 and 1 are connected in this way, the socket 4 in one of the double-walled pipes 1 has a two-layered structure in which the inner wall 2 and the outer wall 3 are integrated.
Moreover, since the inner wall of the socket 5 in the other double-walled pipe 1 is reinforced by the peaks and valleys of the outer wall to form an integrated two-layer structure, the earth pressure resistance strength of the connection part is increased. becomes very large. Moreover, since the inner surfaces of both double-walled tubes 1, 1, that is, the inner surface of the inner wall 2 of one double-walled tube 1 and the inner surface of the insertion port 4 of the other double-walled tube 1, are almost flush with each other. The smooth flow of water is not obstructed even at the connecting parts.

Furthermore, as is clear from Fig. 2b, by setting the length of the socket 4 and the length of the socket 5 to predetermined values, the peak pitch _P1 of the connection part and the other parts can be adjusted. Since Yamabe Pituchi P ₂ is the same,
The shape of the connecting portion and other portions becomes uniform, resulting in a favorable appearance.

FIG. 3a shows a modification. That is, insertion port 4
An annular protrusion 6 is formed at one or a plurality of locations (two locations in the illustrated example). According to this, when the socket 4 is inserted into the socket 5, as shown in FIG. Become something. Note that if the protrusions 6 are formed to correspond to the positions between the troughs 3b in the socket 5, as shown in the example shown in the figure, the inner wall 2 of the socket 5 in the connected state, as shown in FIG. is deformed, and the convex strip 6 engages with the deformed portion in the removal direction, which has the advantage of providing a stronger bonding state.

A preferred method for manufacturing the double-walled tube described above will be explained together with the manufacturing apparatus shown in FIG. 4.

In FIG. 4, 11 is a molten resin extrusion section, and this molten resin extrusion section 11 is a first molten resin passage that opens in an annular shape at the rear end outer periphery of a concave portion 12 of a constant width formed on the outer periphery. 13a and a second molten resin passage 13b opening in an annular shape at the outer circumference of the tip of the extrusion part 11, and a first air supply passage 14a communicating with the recessed part 12 and an annular opening in the second molten resin passage 13b. It has a second air supply passage 14b that opens inside the second molten resin passage 13b, and further has an air intake passage 14c that opens immediately behind the second molten resin passage 13b. A water-cooled cooling cylinder 15 is arranged concentrically at the front of the extrusion part 11, and cooling water is supplied and discharged to and from the cooling cylinder 15 through a cooling water pipe 16 having a double pipe structure that penetrates the extrusion part 11. The configuration is as follows.

Next, 17 is a mold. This mold 17
comprises a tube body molding surface A, a socket molding surface B, and an inlet molding surface C, and the socket molding surface B and the socket molding surface C
is formed so as to be continuous in the middle of the tube body molding surface A in the longitudinal direction. The tube body molding surface A has annular recesses A ₁ and annular projections A ₂ alternately. Similarly to the tube body molding surface A, the socket molding surface B also has circular concave portions B ₁ and convex portions B ₂ alternately, but the convex portions B ₂ are the convex portions A of the tube body molding surface A. It has a larger diameter than ₂ . Note that the recess B ₁ has the same diameter as the recess A ₁ on the molding surface A of the tube body. Further, the insertion port molding surface C has a cylindrical shape with the same diameter as the convex portion _A2 of the tube body molding surface A. In the illustrated example, the mold 17 is divided into a pair of half molds, and each half mold consists of a plurality of molded blocks 17a connected in an endless manner, and these are connected to the molten resin extrusion section 11 and the cooling tube. 5 in the direction indicated by the arrow in FIG. 4 in synchronization at a fixed position.

In such a manufacturing device, the mold 17 is
The molten resin is continuously pushed out through the first molten resin passage 13a and the second molten resin passage 13b of the molten resin extrusion section 11 while traveling at a predetermined speed in the direction of the arrow x in the figure, and at the same time from the first air supply passage 14a. Air is supplied into the concave portion 12 and exhausted from the intake path 14c. In addition, the socket molding surface B is the second air supply path 14b.
Air is supplied from the second air supply path 14b at a predetermined timing when passing through.

In this way, the molten resin extruded into a cylindrical shape from the first molten resin passage 13a is transferred to the tube body molding surface A, the receiving surface, and The molten resin outer layer _P1 is pressed against the mouth molding surface B and the socket molding surface C, and is molded into a shape along each of the molding surfaces A, B, and C. On the other hand, the molten resin pushed out from the second molten resin passage 13b immediately adheres to the inner surface of the molded molten resin outer layer _P1 due to the suction effect caused by exhausting from the intake passage 14c, and is thermally fused. death,
Form a molten resin inner layer _P2 . In this case, the molten resin outer layer formed by the tube body forming surface A
When extruding the molten resin inner layer P ₂ against P ₁ ,
It is necessary to set the suction force through the intake passage 14c to such an extent that the inner layer _P2 does not bulge into the internal space _S1 of the mountain portion of the outer layer _P1 .

By the way, the air supplied from the second air supply path 14b is supplied to the molten resin outer layer formed by the socket molding surface B.
This is carried out only during the time period when P ₁ is passing around the opening of the second molten resin passage 13b. This is because the upper limit of the suction force by the intake passage 14c is regulated for the above-mentioned reason, so by increasing the differential pressure between the inside and outside of the molten resin inner layer _P2 , the inner layer _P2 is This is because it is necessary to reliably adhere to the inner surface of the large-diameter valley portion of the molten resin outer layer P ₁ and heat-seal it. Even in this case, the above differential pressure is
It is necessary to set it to such an extent that P ₂ does not bulge into the internal space S ₂ of the mountain portion of the molten resin outer layer P ₁ .

The inner and outer molten resin layers P ₁ and P ₂ heat-sealed as described above are then sequentially sent to the cooling cylinder 15 side as the mold 17 moves, where they are cooled and hardened. After curing, it is released from the mold.

The molded article P thus obtained is shown in FIG. As shown in the figure, this molded product P has an inlet equivalent part 401 and a receptacle equivalent part 501 that are continuous to each other at multiple equal pitches in the middle of the tube body equivalent part 601.
, the boundary between the socket-equivalent portion 401 and the receptacle-equivalent portion 501 is cut along cutting lines E-I and Rollo to separate them. Furthermore, in the case of FIG. 6, two continuous socket-equivalent parts 401 and two successive socket-equivalent parts 501 are formed, and separated by cutting along cutting lines E-I and R-RO in the center of each. .
In this way, the double-walled pipe 1 explained in FIG.
can be obtained efficiently.

As described in detail above, according to the double-walled pipe of the present invention, double-walled pipes can be easily and quickly connected without using a connecting joint that was conventionally necessary. In addition, at the connection part, the socket has an integrated two-layer structure in which the inner wall is reinforced by the peaks and valleys of the outer wall, and a two-layer structure in which the inner wall and the outer wall are integrated. Since it has a structure in which the socket is inserted, the earth pressure resistance of the connection part is extremely high, and there is no fear that the connection part will deform into a flat shape due to earth pressure. Furthermore, since the inner surfaces of the two double-walled tubes connected to each other are substantially flush with each other, there is an effect that the smooth flow of water is not hindered at the connecting portion. Additionally, since it is difficult to distinguish between the connecting part and other parts, it is superior to conventional products in terms of appearance. Furthermore, according to the manufacturing method of the present invention, it is possible to simultaneously manufacture a plurality of double-walled tubes, so that rationalization and cost reduction of the double-walled tube manufacturing line can be easily achieved.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing an example of a double-walled pipe according to the present invention, Figs. 2a and 2b are illustrations of a connecting procedure for a double-walled pipe, and Figs. 3a and 3b are diagrams showing a double-walled pipe according to a modified example. Connection procedure explanatory diagram, Figure 4 is a sectional view showing the manufacturing equipment for double walls, etc., Figure 5 is an enlarged sectional view of the main part of the molded product, Figure 6 is an enlarged sectional view of the main part of the molded product,
The figure is an enlarged sectional view of a main part of another molded product. 1...Double wall pipe, 2...Inner wall, 3...Outer wall, 3
a... Peak, 3 b... Valley, 4... Socket, 401
... Insertion equivalent part, 5 ... Socket, 501 ... Socket equivalent part, 17 ... Molding mold, A ... Pipe body molding surface,
A ₁ ... Concavities on the tube body molding surface, A ₂ ... Convex portions on the tube body molding surface, B ... ... Socket molding surface, B ₁ ... Concavities on the socket molding surface, B ₂ ... Socket molding surface Convex portion, C... Insertion molding surface, P... Molded product, P ₁ ... Molten resin outer layer,
P ₂ ...Inner layer of molten resin.

Claims (1)

[Scope of Claims] 1. A double-walled tube in which a cylindrical inner wall is disposed along the entire length of an outer wall having annular peaks and valleys alternately, an insertion port at one end and the insertion port at the other end. The socket is provided with a socket into which the socket is inserted, and the inner surface of the valley of the outer wall is heat fused to the inner wall in the part other than the socket, while the outer wall and the inner wall of the socket are They overlap over the entire length and are heat-sealed to each other, and further, the inner diameter of the inner wall is uniform except for the socket, and the inner diameter of the socket is the same or almost the same as the outer diameter of the socket. A double-walled pipe characterized by comprising: 2. A tube body molding surface that alternately has annular concave portions and convex portions, a socket molding surface that alternately has concave portions and convex portions larger in diameter than the aforementioned convex portions, and a socket molding surface that has the same diameter as the convex portions on the tube body molding surface. The molten resin is extruded into a mold equipped with a molding surface to form an outer layer of molten resin along the three molding surfaces, and the molten resin is extruded into the outer layer in a cylindrical shape, creating a pressure difference between the inside and outside of the mold. causing
The molten resin is adhered to the inner surface of the valley part and the inner surface of the part corresponding to the spigot of the outer layer and thermally fused to form a cylindrical molten resin inner layer. A method for producing a double-walled pipe, which comprises cutting and separating the pipe at a predetermined position so as to have a portion corresponding to a socket at both ends.