JPS636348B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a double-walled pipe having a joint portion suitable for use in drainage pipes and the like.

The applicant previously filed Utility Application No. 58-84168 (Utility Model Application No. 84168)
59-190515) proposed a double-walled pipe manufacturing device, and disclosed a method for manufacturing a double-walled pipe in which a continuous uneven outer wall surface was formed on the outside of a cylindrical inner peripheral wall surface. did.

However, when actually using the double-walled pipes manufactured by the device according to this proposal, it is difficult to cut the pipes to predetermined dimensions and connect them using special sockets. had.

The present invention was made in view of the above circumstances, and it is an object of the present invention to provide a method for continuously manufacturing a double-walled pipe having a joint portion from the time of extrusion molding.

Hereinafter, the method of the present invention will be explained in detail using an example of a manufacturing apparatus.

A first example of a manufacturing apparatus for carrying out the method of the present invention is shown in FIG.

That is, a resin extrusion part 10 for extruding molten resin is formed at the tip of the extrusion molding machine 1, and a pair of upper and lower parts are fitted on the sides of this resin extrusion part 10 so as to wrap around the resin extrusion part 10 from the outside. A pair of outer circumferential wall forming split molds 2, 2 each having a semicircular cross section and continuously driven in the extrusion direction of the resin are disposed one above the other.

As shown in FIG. 2, these upper and lower split molds 2 each have an inner circumferential groove 21a with regular annular irregularities.
A large number of uneven peripheral wall molded blocks 21
...and a joint molding block 22 having an uneven inner circumferential groove 22a including a concave portion 22b with a large pitch width.
The joint forming block 22 is formed by connecting a plurality of molded blocks 21 in a rotatable manner endlessly in a caterpillar chain shape, with the upper and lower positions matching, as shown in FIG. are arranged at predetermined intervals.

Further, the resin extrusion section 10 has a first concave step surface 1.
1 and a second concave step surface 12 are formed by cutting out the outer circumferential surface, respectively. The first concave step surface 11 has a nozzle opening of the first annular nozzle 3 opened on the outside, a compressed gas discharge port 13 on the inside, and a second
The concave step surface 12 has a nozzle opening of the second annular nozzle 5 opened on the inside thereof, and a gas vent opening 14 opened on the outside thereof. In the figure, 15 is a bulge, and the first concave stepped surface 1
A sealing member is provided at the distal end of the bulging portion 15 to form a minute gap with the inner circumferential groove of the split mold 2 for forming the outer circumferential wall. A surface 16 is formed.

Therefore, this bulging portion 15 and the first concave stepped surface 1
A substantially sealed space 17 is formed between the mold 1 and the split mold 2, and the molten resin extruded from the first annular nozzle 3 to form the outer peripheral wall of the double wall pipe A is It is pushed by the high-pressure gas discharged from the compressed gas discharge port 13 and adheres closely to the inner circumferential groove of the split mold 2, so that the uneven stepped outer circumferential wall 4 is continuously formed. In the embodiment, normal compressed air is assumed as the gas discharged from the gas discharge port 13, but any type of gas may be used as long as it does not react with the molten resin.

Next, when the uneven stepped outer peripheral wall 4 formed in this way is sent in the resin extrusion direction as the split mold 2 is driven, the molten resin extruded from the second annular nozzle 5 becomes uneven. The inner peripheral wall 6 of the double-walled pipe A is formed by being extruded onto the inner peripheral surface of each recess of the stepped outer peripheral wall 4.

A closed space 18 is formed between the tip of the resin extrusion part 10, the second concave stepped surface 12, and the split mold 2, and the molten resin extruded from the second annular nozzle 5 flows into the concave and convex steps. Before welding the molten resin adhered to the outer circumferential wall 4 to the inner circumferential surface of each recess, the pressurized gas in this space 18 is extracted to the outside from the gas vent 14 to form the space 18, that is, the uneven stepped outer circumferential wall 4. The gas pressure in the space surrounded by the inner surface of the inner wall 6 and the inner peripheral wall 6, which will be described later, is reduced.

When the gas pressure in this space 18, that is, the gas pressure that separates and holds the above-mentioned two resins in a molten state, is high, the inner peripheral wall 6 to be attached to the inner peripheral surface of the outer peripheral wall 4 is in between. The intervening gas pressure makes it easy to peel off, and conversely, if the gas pressure in this space 18 is too low, the inner circumferential wall 6 is easily drawn toward the outer circumferential wall 4 and deformed into a concave state. Proper adjustment of pressure is important.

On the other hand, a cooling part 7 in which a coolant such as water or air is circulated is provided at the tip of the resin extrusion part 10 on the resin extrusion direction side of the second annular nozzle 5.

As shown in FIG. 3, the cooling section 7 is formed into a cylindrical shape with an outer diameter set approximately equal to the inner diameter of the inner circumferential wall 6 of the double-walled pipe A.

A cooling pipe 71 is spirally wound on the outside of the cooling section 7. In particular, in this embodiment, the cooling pipe 71 is connected to the feed pipe 7.
2 and a return pipe 73 are arranged alternately. In addition, a double pipe 10 is provided inside the resin extrusion section 10.
1 is passed through, and a refrigerant supply pipe 102 is installed on the center side.
However, a refrigerant exhaust pipe 103 is provided on the outside. According to such a configuration, the refrigerant sent from the supply pipe 102 is first sent into the feed pipe 72 and sent to the most extreme end of the cooling section 7, and then passes through the return pipe 73 and is sent from the exhaust pipe 103. By discharging the refrigerant to the outside, the refrigerant can be circulated within the cooling section 7 and the cooling section 7 can be efficiently cooled.

Further, a lubricant supply pipe 104 is provided on the outside of the exhaust pipe 103, and this lubricant supply pipe 104 connects a heat insulating material 105 to the outer periphery of the exhaust pipe 103 and the resin extrusion section 1.
The double pipe 101 is formed by inserting the double pipe 101 with a space between it and the inner periphery of the double pipe 101.

Stearic acid, silicone oil, etc. can be used as the lubricant 8 inserted into the lubricant supply pipe 104, and the lubricant 8 sent through the lubricant supply pipe 104 is transferred to a second Annular nozzle 5 and cooling section 7
If the lubricant is discharged from the lubricant outlet 105 formed between the cooling part 7 and the inner circumferential wall 6 of the double-walled pipe A, the double-walled pipe A will be When the resin is sent in the extrusion direction, the cooling section 7
The double-walled pipe A is fed smoothly without rubbing between
It is forcibly cooled from the inside of the inner circumferential wall 6 to maintain its shape.

The thus cooled double-walled pipe A is sent out to the outside as the pair of upper and lower split molds 2 are driven.

As described above, according to the method of the present invention, the molten resin extruded from the first annular nozzle 3 forms the uneven stepped outer circumferential wall 4 of the double wall pipe A, and the molten resin extruded from the second annular nozzle 5 The inner circumferential wall 6 of the double-walled pipe A will be formed with molten resin, and the outer circumferential wall 4 of the resulting double-walled pipe A will have convex portions 42 with large pitch widths arranged at predetermined intervals, as shown in FIG. 4a. It has a shape having an uneven surface 41 at each side.

Therefore, the double-walled pipe A manufactured in this way is cut along the plane including the single convex portion 42 with a large pitch width, for example, along the line X-X' shown in FIG. 4a,
Furthermore, if the inner circumferential wall 61 surrounded inwardly by the cut protrusion 42 is cut along the line Y-Y' shown in FIG. As shown in FIG. 4c, each part becomes a joint part 43 having an opening larger in diameter than the outer circumferential wall 4, and finally a double-walled pipe B having a joint part is obtained.

The thus obtained double-walled pipe B has one end of another similar double-walled pipe B inserted into the joint part 43 as shown in FIG. used in conjunction.

In addition, the joint part 4 of the uneven stepped outer peripheral wall 4 of the double wall pipe B having the joint part manufactured in this way
An engaging protrusion 43a as shown in FIG.
If these protrusions are maintained at appropriate intervals, after the pipes B and B are inserted and connected, the convex portions of the uneven surface 41 of the inserted pipe B will be aligned with these protrusions 42.
It also has the effect of being able to elastically engage with a and prevent it from coming off.

The double-walled pipe B in which the engaging protrusion 43a as shown in FIG. Concave portion 22b with a large pitch width
This can be easily obtained by forming a convex portion (not shown) corresponding to the shape of the engaging protrusion 43a.

When carrying out the method of the present invention, if the manufacturing apparatus described in detail above is used, the hot and easily deformable double-walled pipe A immediately after extrusion molding can be placed inside the extrusion part 10 provided at the tip thereof. Since cooling can be forcibly performed from the inside through the cooling part 7 in which a refrigerant is circulated, it is possible to efficiently cool and maintain the shape. With the lubricant 8 supplied between the peripheral wall 6,
Since the double wall pipe A can be smoothly moved to the outer circumference of the cooling section 7 as the split molds 2, 2 are driven, the double wall pipe A can be manufactured even if the driving speed of the split molds 2, 2 is increased. There is no immediate deformation due to heat, which has the advantage of significantly improving the productivity of the double-walled pipe A.

It should be noted that the method of the present invention can be practiced in addition to the apparatus shown in FIG. 1 described above, and one example thereof is the apparatus shown in FIG. 7 in which the configuration of the cooling section 7 is omitted.

That is, this thing has a resin extrusion part 10 having first and second annular nozzles 3 and 5,
The first annular nozzle 3 is formed of a molded block 2 having an uneven inner peripheral surface, similar to the device of the present invention shown in FIG.
1 and 22 are arranged above and below, and each is arranged so as to be wrapped from the outside by a split mold 2 for forming an outer peripheral wall, which is connected to each other endlessly, and the uneven inner periphery arranged above and below. Forming block 21 with faces
Inside the joint part forming block 22, which has an uneven inner circumferential groove 22a in which a recessed part 22b with a large pitch width is formed to form a joint part, is arranged so that the upper and lower pairs are aligned with each other at a predetermined interval. It is set up.

In addition, in this device, a is the extrusion molding part 1
A sealing plug is formed at the tip of a gas supply pipe d through a core rod c in a cavity b formed at the tip of a double-walled pipe A. It is cooled by pressurized gas or the like, and is continuously taken out from the gap between the sealing plug a and the split mold 2 as the split mold 2 is driven.

Other parts of this apparatus that correspond to the same parts as those of the apparatus shown in FIG. 1 are given the same reference numerals, and the description thereof is omitted.

As detailed above, according to the method of the present invention,
Double-walled pipes with joints can be continuously and efficiently mass-produced using extrusion molding.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing an example of an apparatus for carrying out the method of the present invention, FIG. 2 is a view showing details of a split mold for forming an outer peripheral wall, and FIG. 3 is a resin extrusion diagram of the same apparatus. FIG. 4 is a cross-sectional view showing the structure of the double-walled pipe according to the method of the present invention, and FIG. FIG. 6 is a diagram showing another embodiment of the double-walled pipe described above, showing its connected state; FIG. 7 is a diagram showing the connected state of the wall pipe; FIG. FIG. 3 is a vertical cross-sectional view showing another example of an apparatus for implementing the above. (Explanation of symbols), 2 is a split mold for forming an outer peripheral wall, 3 is a first annular nozzle, 5 is a second annular nozzle, and A is a double wall pipe continuously formed by extrusion molding. , B is a double-walled pipe having a joint portion manufactured by the method of the present invention, 4 is an uneven stepped outer circumferential wall thereof, 43 is a joint portion thereof, and 6 is an inner circumferential wall thereof.

Claims (1)

[Claims] 1. Molten resin extruded from the first annular nozzle,
It is adhered tightly to the inner circumferential groove of a split mold for forming an endless outer circumferential wall having a semicircular cross section, which has an uneven inner circumferential groove including concave portions with large pitch widths at predetermined intervals, and then a second annular nozzle. The extruded molten resin is welded from the inside to the molten resin adhered to the split mold for forming the outer peripheral wall to form a single convex part with a large pitch width at a predetermined interval in each recess of the stepped outer peripheral wall. A double-walled pipe with a cylindrical inner peripheral wall welded to the inner peripheral surface is continuously formed, and then the continuous double-walled pipe is cut at a plane including the convex portion with a large pitch width. A method of manufacturing a double-walled pipe with a joint by cutting out the inner circumferential wall surrounded by this convex part.