JPH0358905B2 - - 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 molten band of synthetic resin is wound spirally around the circumferential surface of a rotating mandrel, and during this winding, the part of the band to be wound later is At the same time, a flexible core material having a specific cross-sectional shape is supplied along the length direction of the strip between the overlapping strips, and the surface Obtained by forming spiral protrusions.

Then, the overlapping parts of the strips are pressed together by one row of pressing rollers (a plurality of rollers are attached to one roller shaft) which are arranged in parallel and opposite to the circumferential surface of the rotating mandrel. Is it then formed into a one-piece corrugated pipe?
101832), 4 to 5 circumferences of the corrugated pipe were successively pressed and joined by a single endless belt, thereby forming the same integral corrugated pipe (Japanese Patent Application Laid-open No. 72082/1983). (see official bulletin).

(C) Problems to be Solved by the Invention However, as mentioned above, when pressing and joining the overlapping parts of the strips using a row of pressing rollers, there is only one row of pressing rollers, and the pressing force of each roller is Since the bonding is done by almost point contact, it is not possible to take a long press bonding time, and if the synthetic resin is hard, bondability may be lacking, while if the synthetic resin is soft, the cross-sectional shape of the spiral protrusions may be distorted. However, there was a problem in that it was difficult to obtain a corrugated pipe with the specified toughness.

On the other hand, when using one endless belt to continuously press and join the overlapping parts of the strips around 4 to 5 circumferences of the corrugated pipe, since there is only one belt, the pressing force against the strips is the entire belt. There is no choice but to be uniform about this. However, the strip changes from a high-temperature molten state to a low-temperature slightly hard state in the direction of axial movement of the corrugated pipe, and if it is pressed uniformly, the pressing force will be too strong in the high-temperature molten state, which is important. There was a problem in that when the spiral protrusions collapsed or were slightly hard, the pressing force was too weak and the overlapping portions could not be sufficiently joined. Further, endless belts are usually made of rubber-based material, and even if the material is heat resistant, it has a problem that it lacks durability because it spends a long time in contact with the high-temperature belt.

(d) Means for solving the problems and their effects This invention consists of (i) supplying a molten synthetic resin strip around a cylindrical mandrel from an extruder;
Wind it spirally so that some parts overlap, and at that time (ii)
Either the synthetic resin strip is supplied so that its cross section is curved or hollow, or (iii) a pre-molded flexible reinforcing material is continuously and simultaneously supplied inside or on the back side of the synthetic resin 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; ) While the corrugated tube, thereby forming a convex portion on the surface, is held on the mandrel,
A plurality of endless belts having concave and/or convex cross-sections engage convex or concave portions of the corrugated pipe to form overlapping portions of the strips of the corrugated pipe, and for each endless belt, one quarter of the corrugated pipe is This is a corrugated pipe manufacturing method characterized by joining and shaping by intermittently pressing every 1/2 turn.

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 sequentially and intermittently engage and press convex and/or concave portions around 1/4 to 1/2 of a corrugated pipe using a plurality of specific endless belts. While pressing and bonding the strips for a sufficient amount of time, the pressing force at each stage of the axial movement of the corrugated pipe can be adjusted (lower the pressing force in soft areas, increase the pressing force in hard areas), Regardless of whether the synthetic resin is soft or hard, the corrugated pipe has at least good bondability, good shaping properties, and strong corrugated pipe, and it also uses multiple separate endless belts. This allows the influence of heat to be distributed to each belt, thereby extending the life of the endless belt and reducing the effort required to replace the endless belt.

In this invention, a plurality of endless belts are used, and the range in which each endless belt engages and presses the convex portion and/or the concave portion of the corrugated pipe is 1/4 to 1/2 circumference of the corrugated pipe. Then, the engagement and pressing of each endless belt is performed intermittently in sequence. Here, the interval between engagement and pressing of each endless belt, that is, the interval between engagement and pressing is preferably 1/6 to 1 circumference of the corrugated pipe. The endless belt may engage and press as much as possible while the corrugated pipe is on the mandrel as a whole, but the total length of the engagement press should be limited to 2 turns (helix angle 2 x
The convex portion and/or concave portion of the corrugated pipe is engaged and pressed for a period of 360 degrees) to 5 turns, more preferably 3 to 4 turns. At this time, the engagement and pressing directions of each endless belt with respect to the corrugated pipe may be the same direction, or may be carried out alternately in opposite directions. Of course, the engagement and pressing by each of these endless belts may be performed not only from the first winding but also after the first two to three turns. Note that when the overlapping portion is along a concave portion, it is desirable to determine the cross section of the endless belt so that the overlapping portion can be directly pressed.

Since each of the endless belts configured as described above comes into contact with the high-temperature synthetic resin, albeit slightly, in a molten state, it is desirable that the endless belt has heat resistance in addition to its original 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. Examples of other endless belt materials include hard rubber, synthetic resin, leather, and metals such as aluminum and aluminum alloys.

In this invention, a cylindrical mandrel is used to continuously feed a corrugated tube in one direction by spirally winding a synthetic resin strip supplied in a molten state from an extruder so as to overlap a part of it. do. Therefore, in a cylindrical mandrel, a large number of rotors are rotatably supported obliquely (obliquely to the axial direction) on the body surface of the cylindrical mandrel, or the mandrel is cylindrical. It consists of an array of thin cylinders, which are arranged parallel to each other and obliquely (with respect to the imaginary cylindrical axis of the mandrel). Furthermore, if the cylindrical mandrel itself does not have the function of feeding the corrugated pipe in one direction,
The mandrel itself may be axially moved laterally using a rail or the like, or the mandrel may be fixed and the synthetic resin extruder may be moved laterally using a rail or the like.

Furthermore, according to one aspect, this invention provides the following (i)
(ii) A corrugated pipe manufacturing device 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 corrugate is held on the mandrel, at least a corrugated pipe is attached to the convex portion and/or the concave portion formed between the convex portions. A corrugated pipe manufacturing device consisting of a plurality of endless belts that are sequentially and intermittently engaged every 1/4 to 1/2 circumference of the corrugated pipe to press the overlapping parts of the corrugated pipe strips.

(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 defined 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, and while the corrugated pipe is held by this mandrel, the convex part and/or the part formed between the convex part. A corrugate consisting of a plurality of endless belts that intermittently engage with the concave grooves at least every 1/4 to 1/2 circumference of the corrugated pipe and press the overlapping portion of the corrugated pipe band. Pipe manufacturing equipment.

Furthermore, according to another aspect of the invention,
The corrugated pipe itself is provided with 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, the corrugated pipe is engaged and pressed by a plurality of endless belts intermittently at every 1/4 to 1/2 circumference of the corrugated pipe, so that The overlapping portions of the strips are sufficiently pressed together and the protruding portions are formed, and therefore, it can be suitably used as a drain pipe that requires particularly strong toughness.

(e) Examples The method of the present invention will be described in detail below based on a specific example of the apparatus shown in the drawings. Note that the method of this invention is not limited thereby.

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 a set 5 of endless belts 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.

In the set of endless belts 5, for example, one endless belt 5x has a cross section corresponding to the cross-sectional shape of the spiral concave line E (described later) of the spiral tube C to be obtained, and is moved by rollers 8x, 9x, and 10x. freely supported. Here, the rollers 8x and 10x are rotatably supported by common roller shafts 8z and 10z, respectively, and the roller 9x is supported so as to be movable left and right by an independent roller shaft 9xz, thereby reducing the pressing force of the belt against the spiral tube C. It is possible to adjust the That is, especially in FIG.
The independent roller shaft 9xz of x is rotatably attached to arm 1.
The arm is supported approximately at the center of 1x, and its upper end is pin-coupled to a bolt and the tip of 13x, and its lower end is pin-coupled to a fixed shaft 12x. and bolt 1
For 3x, adjust the rear part to the fixing plate 14x with 1 nut
It is positioned so that it can move left and right at 5x and 16x.

Note that the other endless belts 5y... are supported by independent roller shafts (not shown) so as to be movable left and right separately from the independent roller shafts 9xz of the endless belt 5x. It has the same configuration as 5x, and the explanation will be omitted.

Next, the operation of the apparatus 1 for continuously manufacturing corrugated pipes having the above configuration will be explained based on FIGS. 1 to 3, 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 convex shape D as a convex portion is 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 part of the band-like body A to be wound later on the previously-wound part of the band-like body A, and this overlapping part is the part of the endless belt. Each belt of set 5 sequentially presses approximately every 1/2 turn, thereby joining. Normally, the speed at which the belt-shaped 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, and furthermore, they become harder every moment after being extruded. Therefore, the joining of the overlapping portions of the above-mentioned strips is often insufficient. Conventionally, a pressure roller or an endless belt is used to press the overlapping parts, but since the pressing force is uniform and the pressing time (or distance) is instantaneous or continuous for a long time, Depending on the condition of the resin, the effect may not be sufficient. However, according to the intermittent wrapping-like pressing by each belt of the endless belt set 5 described above, or the intermittent pressing of approximately 0.5 revolutions of spiral rotation (approximately 360 x 0.5 degrees), the overlapping parts are joined separately. Since the process is performed intermittently by the endless belts 5x, 5y, etc., it is possible to take sufficient time to press and join the band-shaped bodies and adjust the pressing force at each stage of the axial movement of the corrugated pipe (in soft areas, By making the pressing force relatively small and increasing it in hard areas), the jointability of corrugated pipes is guaranteed regardless of whether the synthetic resin is soft or hard.
In addition, since the cross section of the endless belt 5 corresponds to that of the spiral concave strips (concave grooves) as the concave portions formed between the spiral convex stripes, the desired shape, that is, the desired pressure resistance strength as shown in FIG. A corrugated pipe F is obtained. In particular, the rotation of the rotating mandrel 4 is
Immediately after being extruded, the molten band A and the tubular body B are in tension, so 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 usually has a low pressure resistance. However, the above-mentioned endless belt set 5
By adjusting the pressing force and shaping action of the belt 5x, the cross section of the tubular body B is maintained in a predetermined perfect circular shape, and the desired pressure resistance strength is obtained.

Here, each belt of each endless belt set 5,
For example, the pressing force of the belt 5x against the corrugated pipe is determined by adjusting the adjusting nuts 15x and 16 in FIG.
By adjusting the tightening position x, bolt 13
By moving x horizontally left and right, you can adjust it to be stronger or weaker. Note that the through hole of the fixing plate 14x through which the bolt 13x passes is a long hole that is long in the vertical direction.

In addition, instead of the conventional single endless belt, the set 5 of endless belts is replaced with four endless belts as shown in Fig. 1.
If the endless belt is configured with two endless belts, assuming that the pressing time is the same, the time that each endless belt is exposed to high temperatures can be reduced to at least about 1/4, and the life of each endless belt can be extended.

Unlike the above example, the manner in which the strips are superimposed and the tubular body is interposed between these strips can be changed as shown in FIG. 4. In other words, the band
Aa covers the two-wound tubular bodies Ba and Ba from the outside on one horizontal axis (hereinafter, different embodiments with corresponding configurations will be described with reference numerals a, a,
b... may be indicated and the explanation may be omitted).

Next, the spiral tube as described above can also be constructed into a double tube structure. That is, the continuous manufacturing apparatus 1b for corrugated pipes shown in FIG. 5 includes two synthetic resin extruders 2b, 2'b, and further includes two sets of endless belts 5b, 5'b. As shown in Figs. 5 and 6, a molten polyethylene resin strip is first applied from the extruder 2'b around the rotating mandrel 4b.
A'b is supplied, and the band-like body is spirally wound to form a spiral tube C'b. And this spiral tube C′b
is a pipe having no spiral concave or convex ridges, and its spiral overlapping portion is pressed by each endless belt (approximately rectangular in cross section) of the endless belt set 5'b similar to that shown in Figs. 1 and 2. This ensures a secure bond. Next, on the obtained spiral tube C′b, the first
As in Figure 2, the strip Ab and the tubular body Bb are overlapped. Although the explanation is omitted, the obtained corrugated pipe Fb has a double pipe 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. 7, 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 overlapping portion Gc of the belt-like body Ac is pressed and joined by the endless belt 5xc shown by the one-dot chain line, and the belt-like body Ac
The spiral convex shape Dc 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 cross section of the extrusion nozzle is formed into a substantially inverted T-shape corresponding to the cross section of the strip body Ac.

Furthermore, the spiral tube as described above is placed over (on the outside) the inner spiral tube as shown in FIGS. 4 and 6,
It is also possible to construct a double structure as shown in FIG.

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

Figures 9 to 11 Figure 9 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. In addition, the 10th
The example shown in the figure is characterized in that the overlapping portion Gf of the strips Af is structured in a stepped manner, and the example in FIG. 11 is characterized in that the flexible reinforcing material Bg is structured in a square cross section.

Figures 12 to 14 and Figures 15 to 17 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 outward 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. FIGS. 15 to 17 show three examples in which the cross-sectional structures of the strips are different from those described above.

18-20 and 21-27 The cross-sectional structure of the strip includes an inverted U-shaped piece Hl and a horizontal piece Jl extending horizontally outward 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. 21 to 27 show examples in which the cross-sectional structure of the strip is slightly different from the above.

FIG. 28 The strip has a hollow part Lt by profile extrusion. Further, in the corrugated pipe obtained here, the convex portion and the concave portion are engaged and pressed together by the endless belt 5xt.

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.

(F) Effects of the Invention According to this invention, the convex or concave portions of the corrugated pipe are engaged intermittently every 1/4 to 1/2 circumference of the corrugated pipe using a plurality of specific endless belts. Since it is pressed, it is possible to adjust the pressing force at each stage of the axial movement of the corrugated pipe while taking enough time to press and join the strips, and to press and join the overlapping parts of the strips and shape the convex part. As a result, a corrugated pipe suitable as a drain pipe requiring particularly strong strength can be obtained.

[Brief explanation of drawings]

Fig. 1 is a perspective view illustrating the main functions of an example of a corrugated pipe manufacturing apparatus for carrying out the method of the present invention, Fig. 2 is a diagram illustrating the configuration of an endless belt of the apparatus, and Fig. 3 is a diagram illustrating the structure of the endless belt of the apparatus. FIG. 4 is a diagram equivalent to FIG. 3 showing another example, FIG. 5 is a diagram equivalent to FIG. 1 showing another example, and FIGS. Fig. 3 is a diagram corresponding to another example, Fig. 12 is a partial side explanatory view of a corrugated pipe showing another example, Fig. 13 is a longitudinal sectional view of the corrugated pipe, and Fig. 14 is a longitudinal sectional view thereof. FIGS. 15 to 17 are views corresponding to FIG. 14 showing still other examples, FIGS. 18 to 20 are views corresponding to FIGS. 12 to 14 showing still other examples, and FIGS. 21 to 28 14 is a diagram corresponding to FIG. 14 showing still another example. 1... Continuous production equipment for corrugated pipes, 2... Synthetic resin extruder, 3... Reinforcement extruder, 4... Rotating mandrel, 5... Endless belt set, A...
...Band-shaped body, B...Flexible 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 mandrel and wound spirally so that some parts overlap, and at that time ( ii) supplying the synthetic resin strip so that its cross section is curved or hollow; or (iii) supplying a pre-molded flexible reinforcing material continuously and on the inside or back surface of the synthetic resin strip. or (iv) continuously and simultaneously feeding 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 side of the synthetic resin strip. (v) While the corrugated pipe, thereby forming a convex portion on its surface, is held on the mandrel, the overlapping portions of the strips of corrugated pipe are removed from the convex and/or concave portions of the corrugated pipe. A corrugate characterized in that each endless belt is intermittently pressed every 1/4 to 1/2 circumference of a corrugated pipe to perform joining and shaping using a plurality of endless belts having a concave or convex cross section that engage with the corrugated pipe. Method of manufacturing tubes.