JPH11286058A - Production of plastic corrugated pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a plastic corrugated pipe of high commercial value which is free from deformation in a hollow crest part. SOLUTION: In the production of a plastic corrugated pipe by winding a molten plastic belt-shaped mold body 2 having a hollow crest part 2b on one side of a flat belt-shaped part onto the periphery of a mandrel 1 spirally so that the side fringe parts of the mold body 2 overlap each other, a shape-holding slider 7 for shape-holding the crest parts is fitted to the end of a support 7a and inserted into the crest part 2b and arranged, and the slider 7 is slid relatively so that the crest part 2b is spread from the inside by the slider 7 to be prevented from being curved inside to obtain a corrugated pipe P which keep its shape.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a plastic corrugated pipe which is less likely to be deformed.

[0002]

2. Description of the Related Art As one method of manufacturing a plastic corrugated pipe, there is known a method in which a molten plastic strip is supplied from an extruder to the outer periphery of a mandrel and spirally wound.

This method is, specifically, a plastic strip 100 shown in FIG. 10, that is, a plastic strip 100 having a cross section having a fin 100b on one side of a peak 100a and a flat portion 100c on the other side. Is extruded from the extruder and supplied to the mandrel 101, and as shown in FIG.
The plastic band 100 is spirally wound around the outer periphery of the mandrel 101 so that the fin portion 100a and the fin portion 100b overlap the flat portion 100c, and the overlapping portion is fused to form the spiral peak portion 100a and the valley. This is for producing a plastic corrugated pipe having alternating portions.

[0004]

However, when a plastic corrugated pipe is manufactured by the above manufacturing method,
Since the ridge 100a of the plastic strip 100 is distorted by cooling, the ridge 100a is concavely deformed inward as shown by a dashed line in FIG. There was a problem that it was difficult to obtain.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a method for manufacturing a plastic corrugated pipe without substantially deforming.

[0006]

According to a first aspect of the present invention, there is provided a method for manufacturing a plastic corrugated pipe, comprising: a flat band-shaped portion having a hollow ridge on one surface; In the method of manufacturing a plastic corrugated pipe by winding a plastic band-shaped body around the outer periphery of a mandrel in a spiral shape so that the side edges of the band-shaped body overlap with the hollow ridge portion, Attach a shape-retaining slider to the tip of the support rod to retain the shape of the part, insert and place it inside the hollow ridge, and slide the shape-retention slider relatively inside the hollow ridge. It is characterized by the following.

When the slider for shape retention is relatively slid inside the hollow ridge portion of the plastic strip-shaped body as in this manufacturing method, the hollow ridge portion which is likely to be concavely deformed inward with cooling. Since the part is retained in the original hollow shape by the shape retaining slider, the concave convex deformation of the hollow ridge part is prevented, and it is possible to manufacture a plastic corrugated pipe of high commercial value without collapse. .

Further, according to a second aspect of the present invention, there is provided a manufacturing method according to the first aspect of the present invention, wherein a molten plastic band-shaped body having a hollow band on one side of a flat band is formed with the hollow band being outside. A plastic corrugated tube is wound spirally around the outer periphery of the mandrel so that the side edges of the mold overlap, and a flat molten plastic band is spirally wound around the outer periphery so that the side edges overlap. In the manufacturing method, a shape-preserving slider for preserving the hollow convex portion is attached to the tip of the support rod and inserted and arranged inside the hollow convex portion, and the shape-retaining slider is attached to the hollow convex portion. Are relatively slid inside.

In this manufacturing method, the shape-retaining slider is relatively slid inside the hollow ridge of the plastic strip-shaped body in the same manner as in the above-mentioned manufacturing method. Can be prevented by the shape-retaining slider, and a flat plastic strip is spirally wound to form a corrugated pipe (so-called double flat) having a cylindrical smooth outer pipe and having good connectivity. Tube) can be manufactured.

Next, according to a third aspect of the present invention, there is provided the manufacturing method according to the first or second aspect, wherein the shape-retaining slider having the fluid supply port is attached to the tip of the pipe-shaped support rod. It is inserted and arranged inside the hollow ridge of the belt-shaped body, and the shape-retaining slider is relatively slid inside the hollow ridge, and the pipe-shaped support rod and the fluid supply port of the shape-retaining slider are also provided. And supplying a pressurized fluid to the hollow ridges through the ridges.

When the pressurized fluid is supplied to the hollow ridge of the plastic strip-shaped body through the pipe-shaped support rod and the fluid supply port of the shape-retaining slider as in this manufacturing method, the hollow ridge becomes the slider for the shape-retaining. In addition to the shape retention, the hollow ridge is pressed from the inside by the pressure of the fluid, so that the inward concave deformation of the hollow ridge can be reliably prevented. Further, when the pressurized fluid is supplied, the contact pressure between the shape retaining slider and the inner surface of the hollow ridge portion is greatly reduced, and the relative sliding of the shape retaining slider is smoothly performed.

Further, in the manufacturing method according to a fourth aspect of the present invention, in the manufacturing method according to the third aspect, cold pressurized air as a pressurized fluid is supplied to the hollow convex portion of the plastic strip-shaped body. It is assumed that.

When cold pressurized air is supplied to the hollow ridge as in this manufacturing method, the hollow ridge is rapidly cooled from the inside, and the hollow ridge is formed by the shape-retaining slider and the pressure of the air. Since the solidification is performed in a short time while maintaining the shape, it is possible to more reliably prevent the concave deformation of the hollow ridge.

Next, a manufacturing method according to a fifth aspect of the present invention is the manufacturing method according to the first aspect, wherein the pressing belt is provided between the hollow ridges of the plastic band-shaped body wound around the outer periphery of the mandrel. And pressing the overlapping side edges of the plastic band-shaped mold. The manufacturing method according to a sixth aspect of the present invention is the manufacturing method according to the second aspect, wherein Before winding the body, the pressing belt is wound around the concave portion between the hollow ridges of the plastic band-shaped body wound around the outer periphery of the mandrel, and the overlapping side edges of the plastic band-shaped body are pressed. It is assumed that.

When the overlapping side edges of the plastic band-shaped body are pressed by the pressing belt as in the manufacturing methods of the fifth and sixth aspects, the side edges are fused in a close contact state, and the defective fusion is prevented. Eliminate the worry.

Further, a manufacturing method according to claim 7 is characterized in that, in the manufacturing method according to claim 2 or 6, the overlapping side edges of the spirally wound plastic strip are pressed by a pressing roller. Things.

When the overlapping side edges of the plastic band are pressed by the pressing roller as in this manufacturing method, the side edges are fused in a close contact state, and the side edges are hollow ridges of the inner plastic band-shaped body. Since the parts are fused to each other in a close contact state, defective fusion between these parts is eliminated and the bonding strength is improved.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is an explanatory view of a method of manufacturing a plastic corrugated pipe according to an embodiment of the present invention, FIG. 2 is a cross-sectional view of a plastic strip used in the manufacturing method, and FIG. FIG. 4 is a perspective view showing another example of the shape keeping slider attached to the tip of the support rod, and FIG. 5 is a perspective view showing another example of the shape keeping slider attached to the tip of the support rod. FIG. 4 is a partial cross-sectional view showing a state where a side edge is pressed by a pressing belt.

In FIG. 1, reference numeral 1 denotes a mandrel. The mandrel 1 has a structure in which a large number of rolls 1a are arranged in a cylindrical shape, and the rolls 1a are simultaneously rotated by a driving device 1b. Since each roll 1a is inclined at a fixed angle, when the plastic band-shaped body 2 is spirally wound around the outer periphery of the mandrel 1 while simultaneously rotating the rolls 1a, the wound material (plastic corrugate) is formed. The pipe P) can be transferred to the front (to the right in FIG. 1) at a feed pitch corresponding to the inclination angle of the roll 1a.

The molten plastic strip 2 extruded from the extrusion port 3a of the melt extruder 3 is provided with a hollow strip 2b on one side of a flat strip 2a as shown in FIG. An inclined receiving surface 2c is formed on one side edge of the belt-shaped portion 2a, and an inclined overlapping surface 2d is formed on the other side edge. The plastic band-shaped body 2 is spirally wound around the outer periphery of the mandrel 1 so that the receiving surface 2c of the side edge and the overlapping surface 2d overlap each other with the hollow ridge 2b facing outward, and the overlapped receiving member is formed. Surface 2c and overlapping surface 2
d is fused to produce a plastic corrugated pipe P having a smooth inner surface.

As shown in FIG. 1, inside a hollow ridge 2b of a plastic strip 2 extruded from a melt extruder 3, a slider 7 for retaining the hollow ridge 2b is provided. Are attached to the tip of the support rod 7a and inserted and arranged. The shape-retaining slider 7 has a rectangular parallelepiped shape corresponding to the hollow shape of the hollow ridge, as shown in FIG. 3, and has a support rod 7a so as to slide smoothly inside the hollow ridge. Has a tapered shape at its mounting end.
The support rod 7a of the shape-retaining slider 7 is protruded from the inside of the extrusion port 3a of the melt extruder 3 in the extrusion direction, and a portion near the tip of the support rod 7a starts winding of the plastic strip-shaped body 2. It is bent so that it can be inserted exactly into the hollow ridge 2b of the portion.

With the shape-retaining slider 7 attached to the tip of the support rod 7a as described above and inserted and arranged inside the hollow ridge 2b of the plastic band-shaped body 2, the band-shaped body 2 is mandrel-mounted. As it is wound around 1, the shape-retaining slider 7 relatively slides inside the hollow ridge 2b and pushes out the hollow ridge 2b, which is going to be concavely deformed with cooling, from the inside. To maintain the original hollow shape, the hollow ridges 2
It is possible to manufacture a plastic corrugated pipe P having a high commercial value that prevents the concave deformation of b and does not lose its shape.

In this case, as shown in FIG.
c is attached to the tip of a pipe-shaped support rod 7b, which is inserted and arranged inside the hollow ridge 2b of the plastic strip-shaped body 2, and the slider 7 for shape retention When the pressurized fluid is supplied to the hollow ridge 2a through the pipe-shaped support rod 7b and the fluid supply port 7c of the shape-retaining slider while relatively sliding inside the hollow ridge 2b, Not only is the portion 2b retained by the shape retaining slider 7, but also the hollow convex portion 2b is pressed from the inside by the pressure of the fluid.
It is possible to reliably prevent concave bending deformation inward of b. Then, the pressure of the fluid greatly reduces the contact pressure between the shape-retaining slider 7 and the hollow ridge 2b and reduces the frictional force, so that the relative sliding of the shape-retaining slider 7 can be performed more smoothly. You will be

As the pressurized fluid, cold pressurized air (compressed air cooled to room temperature or lower) is preferably used. When such cold pressurized air is supplied from the fluid supply port 7c of the shape retaining slider 7 into the inside of the hollow convex portion 2b, the hollow convex portion 2b is rapidly cooled from the inside, and the shape retaining slider 7 and the Since the hollow ridge 2b is solidified in a short time while maintaining its shape by the pressure of the air, it is possible to more reliably prevent the concave deformation of the hollow ridge 2b. Also, pressurized water or the like can be used, and such water is preferably supplied in a spray state.

The supplied pressurized air flows through the helically continuous hollow ridges 2b and is spontaneously discharged from the opening at the tip thereof. Therefore, it is not necessary to separately form holes for venting air. If the pressure of the pressurized air to be supplied is too high, the hollow ridge 2b swells and deforms outward. Therefore, it is necessary to appropriately adjust the pressure of the pressurized air on site so that such swelling deformation does not occur. It is important.

Further, as shown in FIG. 5, the hollow ridges 2 of the plastic strip 2 wound around the outer periphery of the mandrel 1 are formed.
It is desirable that the pressing belt 4 be wound around the concave portion between b by several turns to press the overlapping side edge of the plastic strip 2. When pressed by the pressing belt 4 in this manner, the receiving surface 2c of the side edge of the plastic strip-shaped body 2 and the overlapping surface 2d are fused in close contact with each other, so that a plastic corrugated pipe P free from defects such as defective fusion is obtained. It becomes possible.

FIG. 6 is an explanatory view of a method of manufacturing a plastic corrugated pipe according to another embodiment of the present invention, FIG. 7 is a cross-sectional view of a plastic strip used in the manufacturing method, and FIG. It is a fragmentary sectional view showing that the overlapped side edge of the mold and the overlapped side edge of the plastic strip are pressed by a pressing belt and a pressing roller, respectively.

This manufacturing method is for manufacturing a corrugated pipe P having a cylindrical smooth outer pipe called a double flat pipe.
a, a plastic strip 2 having a hollow ridge 2b on one side is extruded from an extrusion port 3a of a melt extruder 3 and supplied to the mandrel 1, and the hollow ridge 2b is placed outside the mandrel 1. while winding a plastic strip-type body 2 helically, by fusing overlapping receiving surface 2c and the superposed surfaces 2d of the side edges, and so as to form a corrugated inner tube P _1.

Then, as shown by a dashed line in FIG. 6, a shape-retaining slider 7 is attached to the tip of the support rod 7a and inserted and arranged inside the hollow ridge portion 2b of the plastic band-shaped body 2. While the slider 7 is relatively slid inside the hollow ridge 2b, the hollow ridge 2b to be concavely deformed is pushed out from the inside to maintain the hollow shape, and the concave of the hollow ridge 2b is maintained. and to be able to form the corrugated inner tube P ₁ is not loss of shape to prevent deformation.

In this case, the fluid supply port 7 as shown in FIG.
c is attached to the tip of a pipe-shaped support rod 7b and inserted and arranged inside the hollow ridge 2b of the plastic band-shaped body 2, and pressurized fluid such as cold pressurized air is attached. May be supplied from the fluid supply port 7c of the shape-retaining slider to the hollow ridge 2b to more surely prevent the hollow ridge 2b from being concavely deformed in the same manner as described above.

Further, in this manufacturing method, a flat molten plastic strip 5 having inclined receiving surfaces 5a and overlapping surfaces 5b on both side edges as shown in FIG. extruded from the extrusion port 30a, wound plastic strip member 5 as receiving surfaces 5a and overlapped surface 5b of the side edges overlap in a spiral manner around the circumference of the corrugated inner tube P _1,
Thereby forming a superimposed receiving surface 5a and overlaid smooth outer tube of by fusing a cylindrical surface 5b P _2, by fusing the outer tube P ₂ into corrugated inner tube P _1, double flat tube P Has been manufactured.

Also in this manufacturing method, before the flat plastic strip 5 is wound, as shown in FIG. 8, between the hollow ridges 2b of the plastic strip 2 wound around the outer periphery of the mandrel 1. It is desirable that the pressing belt be wound around the concave portion by a few turns to press the overlapping side receiving surface 2c and the overlapping surface 2d.
To fuse the superposed surfaces 2d is in close contact with, it is possible to form the corrugated inner tube P ₁ is free from defects such as fusion defects.

As shown in FIG. 8, it is desirable that the overlapping side edges of the flat plastic band 5 wound are pressed by the pressing rollers 6 and 6. with receiving surfaces 5a and overlapped surface 5b of the rim can form an outer tube P ₂ without fusion defects are fused in tight contact, the outer tube P ₂ are corrugated inner tube P ₁
Of the inner pipe P ₁ to be fused to the hollow ridge 2b in a close contact state.
Bonding strength of the outer pipe P ₂ it is possible to obtain a large double flat tube P and.

In each of the manufacturing methods of the above-described embodiments, the plastic band-shaped body 2 provided with one hollow ridge 2b on one surface of the band 2a is used, for example, as shown in FIG. As described above, a plastic strip 2 having two hollow ridges 2b, 2b on one surface of the strip 2a may be used, and a plastic strip having three or more hollow ridges may be used. You may.

[0036]

As is evident from the above description, the manufacturing method of the present invention provides a plastic corrugated pipe having a high commercial value, which prevents deformation of the hollow ridges of the plastic strip-shaped body and has no deformation. It has a remarkable effect that it can be easily mass-produced by yield.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a method for manufacturing a plastic corrugated pipe according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a plastic strip used in the manufacturing method.

FIG. 3 is a perspective view showing an example of a shape-retaining slider attached to a tip of a support rod.

FIG. 4 is a perspective view showing another example of the shape-retaining slider attached to the tip of the support rod.

FIG. 5 is a partial cross-sectional view showing a state where overlapping side edges of the plastic strip-shaped body are pressed by a pressing belt in the same manufacturing method.

FIG. 6 is an explanatory diagram of a method for manufacturing a plastic corrugated pipe according to another embodiment of the present invention.

FIG. 7 is a sectional view of a plastic strip used in the manufacturing method.

FIG. 8 is a partial cross-sectional view showing that the overlapping side edge of the plastic strip and the overlapping side edge of the plastic strip are pressed by a pressing belt and a pressing roller, respectively, in the same manufacturing method. .

FIG. 9 is a cross-sectional view showing another example of the plastic band-shaped body.

FIG. 10 is a partial cross-sectional view illustrating a method for manufacturing a conventional plastic corrugated pipe.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 Mandrel 2 Plastic strip 2a Strip 2b Hollow ridge 2c Receiving surface 2d Stacking surface 3,30 Melt extruder 3b Fluid supply passage 4 Press belt 5 Flat plastic strip 5a Receiving surface 5b Stack surface 6 Press roller 7 Shape-retaining slider 7a Rod-shaped support rod 7b Pipe-shaped support rod 7c Fluid supply port

Claims (7)

[Claims] 1. A molten plastic strip having a hollow strip on one side of a flat strip is spirally wound so that the side edges of the strip overlap with the hollow strip being outside. In a method of manufacturing a plastic corrugated pipe by winding the outer periphery of a mandrel, a shape retaining slider for retaining the hollow convex portion is attached to the tip of the support rod and inserted into the hollow convex portion, A method for manufacturing a plastic corrugated pipe, comprising disposing and relatively sliding a shape retaining slider inside a hollow ridge. 2. A molten plastic strip-shaped body having a hollow ridge on one side of a flat strip is spirally wound so that the side edges of the strip overlap with the hollow ridge being outside. In a method of manufacturing a plastic corrugated tube by winding a flat molten plastic band around the outer periphery of a mandrel and further spirally winding a flat molten plastic band so that its side edges overlap with each other, A shape-retaining slider for shape-retaining is attached to the tip of the support rod, inserted and arranged inside the hollow ridge, and the shape-retaining slider is relatively slid inside the hollow ridge. Method for manufacturing a plastic corrugated pipe. 3. A shape-retaining slider having a fluid supply port is attached to the tip of a pipe-shaped support rod, and inserted and arranged inside a hollow convex portion of a plastic strip-shaped body. The pressurized fluid is supplied to the hollow ridge portion through the fluid supply port of the pipe-shaped support rod and the shape-retaining slider, while being relatively slid inside the portion. The production method described in 1. 4. The method according to claim 3, wherein cold pressurized air is supplied as a pressurized fluid to the hollow ridges of the plastic strip. 5. A plastic belt-shaped body wound around an outer periphery of a mandrel, wherein a pressing belt is wound around a concave portion between hollow ridges to press overlapping side edges of the plastic band-shaped body. Item 1. The production method according to Item 1. 6. A winding belt is wound around a concave portion between the hollow ridges of the plastic band-shaped body wound around the outer periphery of the mandrel before the plastic band-shaped body is wound. 3. The method according to claim 2, wherein the edge is pressed. 7. The method according to claim 2, wherein the overlapping side edges of the spirally wound plastic strip are pressed by a pressing roller.