JPH0572852B2 - - Google Patents

Description

[Detailed Description of the Invention] (a) Field of Industrial Application This invention relates to a method for manufacturing corrugated pipes, and more specifically, because of their high pressure resistance, they are often buried in the ground and used as drainage pipes. The present invention relates to a method of manufacturing a corrugated pipe, particularly a corrugated pipe having a spiral convex portion on its surface.

(B) Prior art In general, there are two types of corrugated pipes, one in which the concave and convex shapes of the pipe wall are axially symmetrical and the other in a spiral shape. For example, a belt-shaped body made of molten synthetic resin is spirally wound around the circumferential surface of a rotating mandrel, and the part of the belt-shaped body that is wound later than the part of the belt-shaped body that was wound earlier during this winding. At the same time, a flexible core material having a specific cross-sectional shape is supplied along the length direction of the strips between the overlapping strips, and the surface It is obtained by forming spiral protrusions on.

The overlapping parts of the strips are pressed together by one pressure roller installed parallel to the peripheral surface of the rotating mandrel, thereby forming an integral corrugated pipe (Japanese Patent Laid-Open No. 56-101832 (see publication).

(C) Problems to be Solved by the Invention However, as described above, when pressing and joining the overlapping parts of the strips using a pressing roller, there is only one pressing roller, and the pressing force is almost point contact. If the synthetic resin is hard, the bonding performance may be lacking, and if the synthetic resin is soft, the cross-sectional shape of the spiral convex strip may be distorted, and the desired toughness may not be achieved. There was a problem that corrugated pipes were difficult to obtain.

(d) Means for solving the problems and their effects The present invention consists of (i) supplying a molten synthetic resin strip from an extruder around a cylindrical rotating mandrel and partially overlapping it; At that time, (ii) the synthetic resin strip is supplied so that its cross section is curved or hollow, or (iii) the pre-molded flexible reinforcing material is wound with the synthetic resin. Continuously and simultaneously feeding inside or on the back side of the strip, or
(iv) continuously and simultaneously supplying a flexible reinforcing material of the same or different synthetic resin as the synthetic resin from the extruder or another extruder to the inside or back surface of the synthetic resin strip; Therefore, the corrugated pipe having a convex portion formed on its surface is continuously fed out by the rotating mandrel in the axial direction of the rotating mandrel, and while the corrugated pipe is held on the rotating mandrel, the strip of the corrugated pipe is A corrugate characterized in that the overlapping portion is extruded and joined and shaped over at least half the circumference of the corrugated pipe by a linear extruded member having a concave cross section that engages the convex portion and the concave portion of the corrugated pipe. This is a method for manufacturing tubes.

That is, this invention consists of steps (i) to (v), and among these five steps, step (v) is one of the main structural features, and the other steps (i) to ( All of step iv) are known steps, and any one of steps (ii) to (iv) is selected and employed.

In short, this invention makes it possible to engage and press the convex portion and the concave portion of the corrugated pipe simultaneously in a linear manner over half the circumference or more by using a specific linear pressing member, and thereby The softness of
Regardless of the hardness, the corrugated pipe has at least good joining performance, and also has good shaping properties, so that a strong corrugated pipe can be obtained.

In particular, using a rotating mandrel as the mandrel,
What is a linear pressing member that allows the corrugated pipe to be continuously fed out in the axial direction of the rotating mandrel only by the rotation of the rotating mandrel, and thereby performs feeding of the corrugated pipe, joining and shaping of the corrugated pipe? Separate it so that it can be done only with a rotating mandrel. By transmitting the delivery force to the corrugated tube from the inner surface of the corrugated tube in this manner, the shaping of the outer surface of the corrugated tube is improved.

In the present invention, a linear pressing member means a linear pressing member that continues a convex portion of a corrugated pipe or a concave portion formed between the convex portions over about half the circumference of the corrugated pipe or more, that is, a helical angle of about 180 degrees or more. means a member that engages and presses at the same time, specifically,
As shown in the examples, an endless belt is preferred. The range in which the linear pressing member engages and presses the convex portion and the concave portion may be the entire range while the corrugated pipe is on the mandrel, but it is preferable to wrap the body around 1 to 5 times (helical angle of 360 degrees). , more preferably 2 to 4 turns of the body. Of course, these windings may be performed not only from the first winding but also after the first two or three turns.

Since the endless belt configured as described above constantly comes into contact with the high-temperature synthetic resin in a molten state, it is particularly required to have heat resistance in addition to its inherent toughness and flexibility. A specific example of the material is a cloth laminated with rubber, and heat-resistant rubber is particularly used as the rubber. of course,
Such an endless belt is preferably cooled by cold water, cold air, or the like.

In this invention, a cylindrical mandrel is used to continuously feed a corrugated tube in one direction by winding a synthetic resin strip supplied in a molten state from an extruder in a spiral manner so as to overlap a portion of the synthetic resin strip. . Therefore, specifically, the cylindrical mandrel is formed diagonally (with respect to the axial direction) to the original body surface of the cylindrical mandrel.
Either a number of rotors are rotatably supported, or the mandrel is constructed of a cylindrical array of thin cylinders parallel to each other and oblique (with respect to the imaginary cylindrical axis of the mandrel). ) are arranged.

Furthermore, according to one aspect, this invention provides the following (i)
(ii) A corrugated pipe manufacturing apparatus is provided.

(i) A synthetic resin extruder that extrudes a molten synthetic resin strip, and a flexible reinforcing material made of the same or different synthetic resin from this extruder or another extruder, or a pre-molded flexible reinforcing material; A reinforcing material extruder that extrudes the reinforcing material, and a reinforcing material extruder that spirally winds the strip from the synthetic resin extruder and applies the reinforcing material inside or on the back side of the strip along the longitudinal direction of the strip. A flexible reinforcing material is supplied from the above to form a convex part on the surface, and a part of the part of the band-like body to be wound later is overlapped with the part of the band-like body wound earlier to form a convex part on the surface. A rotating mandrel for forming a corrugated pipe having a shaped portion, and while the corrugated pipe is held on this mandrel, at least the corrugated pipe has a convex portion and/or a grooved portion formed on the convex portion. A corrugated pipe manufacturing device comprising an endless belt that continuously and simultaneously engages over half the circumference and presses the overlapping portion of the corrugated pipe band.

(ii) A synthetic resin extruder that extrudes a molten synthetic resin strip so that its cross section becomes curved or hollow; and a synthetic resin extruder that extrudes a molten synthetic resin strip so that its cross section becomes curved or hollow; A reinforcing space is formed along the longitudinal direction of the strip inside or on the back side of the strip, and a convex strip is formed on the surface of the strip, and the strip is wound later on the part of the strip that was wound earlier. A rotating mandrel for forming a corrugated pipe having a convex part on its surface by overlapping a part of the parts thereof, and while the corrugated pipe is held on this mandrel, the convex part and/or the formation between the convex part. An apparatus for manufacturing a corrugated pipe, which comprises an endless belt that continuously and simultaneously engages the grooved portion over at least half the circumference of the corrugated pipe and presses the overlapping portion of the band-like bodies of the corrugated pipe.

Furthermore, according to another aspect, the present invention provides a corrugated pipe itself having a specific configuration.

That is, the corrugated pipe is made by winding a synthetic resin strip in a spiral shape, and inserting a flexible reinforcing material or defining a reinforcing space inside or on the back surface of the strip along the longitudinal direction of the strip. This is a corrugated pipe with protrusions formed on its surface. During manufacturing, this corrugated pipe has ridges and/or
Alternatively, since the concave portion is continuously engaged and pressed by the linear member, the overlapping portions of the strips are pressed together and the convex portion is sufficiently formed, and therefore particularly strong toughness is required. It can be suitably used as a drain pipe.

(e) Examples The method of the present invention will be described in detail based on specific reference examples and examples shown in the figures below. Note that the method of this invention is not limited thereby.

[Reference example]

First, in FIG. 1, a corrugated pipe continuous manufacturing apparatus 1 includes a synthetic resin extruder 2 that continuously extrudes a synthetic resin strip A in a molten state, and a synthetic resin tubular body B as a flexible reinforcing material. a reinforcing material extruder 3 for extruding the reinforcing material, and a rotating mandrel 4 for continuously forming a helical tube C by overlapping and winding the strip A and the tubular body B supplied from these extruders in a spiral shape.
and an endless belt 5 as a linear pressing member for pressing and joining the overlapping portions of the obtained helical tubes C and shaping the helical convex ridges D to be described later.

The rotating mandrel 4 has a plurality of hollow shafts 6, 7...
... are arranged in parallel at predetermined intervals along the circumferential surface of one virtual cylinder, and each hollow shaft is connected to a sprocket provided at the shaft end (left side in Figure 1), not shown, by a chain. The rotating mandrel 4 is configured to rotate at a constant speed in the same direction, thereby substantially rotating the rotating mandrel 4.

The endless belt 5 has a cross-section corresponding to the cross-sectional shape of a helical groove E, which will be described later, of the obtained helical tube C, and is movably supported by rollers 8, 9, and 10.

Next, the operation of the apparatus 1 for continuously manufacturing corrugated pipes having the above configuration will be explained based on FIGS. 1 and 2, and a method for continuously manufacturing corrugated pipes will be explained accordingly.

The rotating mandrel 4 is rotated (substantially), and the synthetic resin extruder 2 is placed around the rotating mandrel 4.
When a molten polyethylene resin strip A is supplied, the strip is spirally wound to form a spiral tube C. Further, when the strip A is wound, a polyethylene resin tubular body B is supplied from the reinforcing material extruder 3 to the back side of the strip A along the longitudinal direction of the strip A. In this way, the spiral protrusions D as convex portions are formed on the surface of the helical tube C, and the appearance of the corrugated tube F is substantially arranged.

Further, the above-mentioned spiral tube C is formed by overlapping a portion of the band-like body A to be wound later on the previously-wound part of the band-like body A, and this overlapping portion forms the endless belt 5. It is pressed into a wrapper shape and joined by this. Normally, the speed at which the belt-like body A and the tubular body B are pulled by the rotation of the rotating mandrel 4 is faster than the speed at which each of these bodies is extruded, and both bodies are still in a soft state, so that the overlapping portions of the above-mentioned belt-like bodies are joined. Although this is sometimes done, it is often insufficient. For this,
Conventionally, a pressure roller has been used to press the overlapping portions, but since the pressing time (or distance) is instantaneous, the effect may not be sufficient depending on the state of the synthetic resin. However, according to the wrapping-like pressure by the endless belt 5 described above, that is, the continuous pressure during about 3.5 spiral rotations (about 360 x 3.5 degrees),
Since the overlapping parts are joined continuously for a long period of time, 10 parts are guaranteed. In addition, the cross section of the endless belt 5 corresponds to that of the spiral concave strips (concave grooves) as concave portions formed between the spiral convex strips, and is similarly engaged continuously for a long time, so that the desired shape, that is, A corrugated pipe F having the desired pressure resistance strength is obtained.
In particular, the rotation of the rotating mandrel 4 puts the molten band-like body A and tubular body B in tension.
For example, the tubular body B tends to become flattened in the direction parallel to the rotation axis of the rotating mandrel 4, and therefore a decrease in pressure resistance is usually unavoidable. The predetermined perfect circular shape is maintained, and the desired compressive strength is obtained.

Unlike the above example, it is also possible to change the manner in which the strips are superimposed and the tubular body is interposed between these strips, as shown in FIG. 3. In other words, the band A
has one width and covers the two-wound tubular body Ba, Ba from the outside.

Next, a continuous corrugated pipe manufacturing apparatus 1b shown in FIG. 4 is equipped with two synthetic resin extruders 2b and 2'b, and further equipped with two endless belts 5b and 5'b. That is, first, a molten polyethylene resin strip A'b is supplied from an extruder 2'b around a rotating mandrel 4b, and the strip is spirally wound to form a spiral tube C'b. . This spiral tube C'b is a tube having no spiral concave or convex ridges, and the overlapping spiral portion is pressed by an endless belt 5'b, thereby ensuring the joining. Next, on the obtained spiral tube C′b, the first
Similarly to the figure, the strip Ab and the tubular body Bb are overlapped. Although the explanation is omitted, the obtained corrugated pipe
Fb has a double tube structure as shown in FIG.
Note that Gb and Gb are the overlapping portions of the strips A'b.

Unlike each of the above examples, the synthetic resin tubular body may be inserted into the inside of the band-shaped body and wound spirally. That is, in FIG. 6, a synthetic resin tubular body Bc is inserted into the synthetic resin band Ac in a molten state, and is spirally wound around a rotating mandrel (not shown) to form a spiral tube. Then, the belt-shaped body Ac is
The overlapping portion Gc of is pressed and joined, and the strip
The spiral convex ridge Dc of Ac is shaped. In addition, the band Ac
is obtained by feeding the previously molded tubular body Bc into a synthetic resin extruder, and extruding it together with the molten synthetic resin from an extrusion nozzle while maintaining the tubular body Bc in the center. Of course, the opening of the extrusion nozzle is formed into a substantially inverted T-shape in cross section corresponding to the cross section of the strip Ac.

Furthermore, the spiral tube as described above can be placed over (outside of) the inner spiral tube as shown in FIGS. 4 and 5 to form a double structure as shown in FIG. 7.

Examples of other cross-sectional structures of corrugated pipes are listed below.

Figures 8 to 10 Figure 8 shows an example in which a flexible reinforcing material Be, such as a hard vinyl chloride resin, is inserted on the back surface of the strip Ae along the longitudinal direction of the strip Ae. The example shown in FIG. 9 is characterized in that the overlapping portion Gf of the strips Af is structured in a stepped manner, and the example in FIG. 10 is characterized in that the flexible reinforcing material Bg is structured in a square cross section.

Figures 11 to 13 and Figures 14 to 16 The cross-sectional structure of the strip consists of an inverted U-shaped piece Hh and large and small horizontal pieces Ih and Jh extending horizontally from both ends of this piece. The joining part, the small horizontal piece Jh, and the tip of the large horizontal piece Ih are overlapped,
They are joined by an endless belt (not shown) as appropriate. 14 to 16 show three examples in which the cross-sectional structure of the strip is different from the above.

17-19 and 20-26 The cross-sectional structure of the strip includes an inverted U-shaped piece Hl and a horizontal piece Jl extending horizontally from one end (right end) of this piece.
It consists of a hard piece part consisting of an inclined piece Il extending slightly downward from the other end, and a soft piece part Kl that closes the downward opening part of this hard piece. Figures 20 to 26 are
Examples will be shown in which the cross-sectional structure of the strip is slightly different from the above.

〔Example〕

FIG. 27 The strip has a hollow portion Lt by profile extrusion. Further, in the corrugated pipe obtained here, the convex portion and the concave portion are both engaged and pressed by the endless belt 5t. Of course, the corrugated pipe manufacturing method and apparatus in this case can be the same as those shown in FIG. 1, with the only difference being the cross section of the endless belt, so the explanation will be omitted.

Different from the above example, two flexible reinforcing materials are simultaneously inserted side by side into the inside or back side of one synthetic resin strip and wound spirally, thereby forming a corrugated pipe having two spiral ridges. may be formed. Of course, two independent endless belts are used in this case.

(F) Effects of the Invention According to this invention, since the convex portion and the concave portion of the corrugated pipe are continuously engaged and pressed by a specific linear pressing member, it is possible to press and join the overlapping portions of the strips. The convex portions are sufficiently shaped, thereby providing a corrugated pipe suitable as a drain pipe that particularly requires toughness.

[Brief explanation of drawings]

FIG. 1 is a perspective view illustrating the functions of the main parts of a corrugated pipe manufacturing apparatus as a reference example for explaining the method of the present invention, FIG. Figure 3 is a diagram equivalent to Figure 2 showing another reference example, and Figure 4 is a diagram equivalent to Figure 1 showing another reference example.
Figure 5 is a diagram equivalent to Figure 2, and Figures 6 to 1 are equivalent to Figure 5.
Figure 0 is a diagram equivalent to Figure 2 showing other reference examples, Figure 11 is a partial side explanatory view of a corrugated pipe showing another reference example, Figure 12 is a longitudinal sectional view of the corrugated pipe, Figure 13 is an enlarged cross-sectional view of the main part of the vertical cross-sectional view, Figures 14 to 16 are views corresponding to Figure 13 showing still other reference examples, and Figures 17 to 19 are views 11 to 13 showing still other reference examples. Figure equivalent figure, No. 20-26
The figure is a diagram equivalent to FIG. 13 showing yet another reference example. FIG. 27 is a view corresponding to FIG. 13 for explaining an embodiment of the method for manufacturing a corrugated pipe according to the present invention. 13 is a diagram corresponding to FIG. 13 showing still another example. 1... Continuous production equipment for corrugated pipes, 2... Synthetic resin extruder, 3... Reinforcement extruder, 4... Rotating mandrel, 5... Endless belt, A... Band-shaped body, B... Flexibility Reinforcement material, C... spiral tube, D...
...Spiral convex ridge (convex portion), F...Corrugated pipe.

Claims (1)

[Claims] 1 (i) A molten synthetic resin strip is supplied from an extruder around a cylindrical rotating mandrel,
(ii) supply the synthetic resin strip so that its cross section is curved or hollow; (iv) a flexible reinforcing material of the same or different synthetic resin from the extruder or another extruder; (v) The corrugated tube, which forms a convex portion on the surface, is continuously and simultaneously supplied to the inside or back surface of the synthetic resin strip by the rotating mandrel in the axial direction of the rotating mandrel. While the corrugated tube is being fed out and the corrugated tube is held on a rotating mandrel, the overlapping portions of the corrugated tube strips are
A method for producing a corrugated pipe, which comprises performing extrusion joining and shaping over at least half the circumference of the corrugated pipe using a linear extruded member having a concave cross section that engages the convex portion and the concave portion of the corrugated pipe.