JP3212387B2 - Extrusion molding method of synthetic resin pipe with inner spiral rib or groove - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for extruding a synthetic resin tube having an internal spiral rib or a groove.

[0002]

2. Description of the Related Art As a method for continuously producing a synthetic resin pipe with an internal spiral rib used as a vertical drainage pipe of a building, a production method as disclosed in Japanese Patent Publication No. Sho 49-42670 has been proposed. In this method, as shown in FIG. 10, a thermoplastic resin tube 103 having one or two or more ridges or grooves in a length direction is continuously formed from a mold (die) 102 of an extruder 101 on the inner surface of the tube. Extrude. Then, the extruded softened tube 103 is immediately put into the outer diameter former 10.
4 and a cooling jacket 105 provided on the outside of the tube 103 to cool while regulating the outer diameter, and then take up the twisted portion of the tube 103 while twisting the softened portion of the tube 103 by a take-off roll 106 which can rotate independently perpendicular to the tube axis. Like that.

[0003] That is, the outer diameter former 104 is
02 prevents the expansion of the pipe 103, and the cooling jacket 10 of the outer diameter former 104.
5 cools the tube surface rapidly so that the tube surface is not deformed. Then, when the pipe 103 is pulled while being twisted, the inner surface side of the pipe 103 is twisted, and a ridge or a concave groove is formed into a spiral shape.

[0004]

However, in the above method, since the softened portion of the tube 103 is formed by forcibly twisting, the distortion of the outer surface of the tube> the distortion of the inner surface of the tube> the distortion of the central portion of the tube. There is a difference in distortion remaining on the outer and inner surfaces of the tube, referred to as distortion. Therefore, deformation such as twisting easily occurs after piping. Also, particularly, when hot waste water flows down in the pipe, the temperature of the pipe rises and the elastic modulus decreases, so the pipe tries to return to the state in the extrusion die, that is, the straight pipe state without ridges or grooves. . That is, the helical ribs and grooves become smaller, and a predetermined drainage capacity may not be obtained.

Therefore, the inventors of the present invention have provided a spiral groove corresponding to the spiral rib on the surface of the extrusion core on the outlet side of the fixed core, and have a parison (run-down) in which the spiral rib is formed on the inner surface while being spirally rotated. Forming apparatus having a high-temperature molten state or softened state extruded in a state, and continuously extruding the extruded parison in the circumferential direction of the tube. A method is disclosed in Japanese Patent Application No. Hei 4-10120, in which a pipe having a desired outer diameter is cooled and solidified while being shaped into a pipe having a desired outer diameter, and the pipe is drawn at a speed synchronized with the extrusion speed and the rotation speed of the parison.
No. 5 has already proposed this.

According to this method, it is possible to obtain a synthetic resin tube with internal spiral ribs without applying a load such as torsion to the extruded high temperature molten or softened parison portion. Since the synthetic resin pipe with spiral ribs does not have large distortion left and there is no difference in distortion between the inside and outside of the pipe, it causes deformation such as twisting after piping, and the spiral due to the effects of hot drainage flowing inside. The ribs do not become smaller and provide a very good effect.

That is, as shown in FIG. 11, the above-mentioned method is performed by extruding a forming apparatus 203 having a forming plate portion 231 as forming means and a cooling water tank 232 as cooling means from an extrusion die (not shown). The formed parison 251 is guided, shaped into a desired outer diameter by a forming plate portion 231 without load, and cooled and solidified by spraying cooling water from a cooling water pipe 237 in a cooling water tank 232 to obtain a pipe 252 having a desired outer diameter. I have to. In addition, the cooling water tank 237 is configured such that the inside air is degassed together with the cooling water from a vacuum pipe 238 connected to a vacuum pump (not shown) to be in a reduced pressure state. That is, the outlet of the tube 252 is sealed by the rubber packing 239 so that a reduced pressure state can be maintained. And the forming device 2
At the rear of 03 (the take-up machine side), the tube 252 is taken up while being spirally rotated by a take-up machine (not shown) while being supported by the rubber packing 239.

However, in the above method, the tube 252 shaped by the forming plate portion 231 is not yet sufficiently solidified, and the elasticity of the rubber packing 239 and the tube 252
Since the tube 252 is pulled down while being bent by its own weight, and the tube 252 is taken up while rotating, the finally formed tube 252 does not bend and bend in one direction, but becomes a tube 252 bent in a spiral shape. Would.

That is, the spirally bent pipe 252 has a considerably lower commercial value as a pipe bent in one direction, and when used as an inner pipe of a lining steel pipe, There is a problem that it is very difficult to insert into. In view of such circumstances, the present invention does not cause deformation such as torsion after piping, or the spiral rib does not become small due to the influence of hot drainage flowing through the inside, and the drainage capacity is semipermanently impaired. It is an object of the present invention to provide a method of extruding a synthetic resin tube having an inner spiral rib or a groove having a good commercial value and a good appearance without bending.

[0010]

According to the present invention, there is provided a method for extruding a synthetic resin pipe having an internal spiral rib or groove according to the present invention. After being continuously extruded while being helically rotated from the extrusion die, the extruded parison is passed through a forming device having a forming means and a cooling means rotatable in the circumferential direction, and cooled while shaping into a tube having a desired outer diameter. An extruding method of an inner spiral rib or a grooved synthetic resin tube for solidifying and further drawing the tube at a speed synchronized with the extrusion speed and the rotation speed of the parison, wherein the outer tube is formed by the forming means. At least one ring-shaped member made of a hard material having an inner diameter substantially equal to or slightly larger than the diameter is disposed in a forming device behind the forming means, and And the shaped tube by penetrating into the ring-shaped member and configured to subject the pipe to be taken up by the inner wall surface of the ring-shaped member in Mingu means.

In the above structure, the method of extruding the synthetic resin tube from the mold while spirally rotating while forming a spiral rib or groove on the inner surface includes forming a spiral shape corresponding to the spiral rib on the outlet side surface of the fixed core of the mold. There is a method of forming a helical ridge corresponding to the concave groove or the helical groove, and a method of connecting a mold provided so that the core is rotated by a crosshead method.

The synthetic resin forming the tube is not particularly limited, and examples thereof include polyvinyl chloride, post-chlorinated polyvinyl chloride, polyethylene, and nylon. Further, as described above, the outlet of the fixed core is used. When the tube is extruded by a method in which a spiral groove or a ridge is provided on the side, a synthetic resin having an apparent viscosity of 1000 poise or more is particularly preferable.

That is, when the apparent viscosity is less than 1000 poise, the molten resin is not smoothly guided into the spiral groove.
The molten resin that has once entered the spiral groove is extruded into a part without the groove. Therefore, there is a possibility that irregularities may be formed in a portion of the inner surface of the tube that should be smooth, that is, a portion where the rib is not formed, a discontinuous rib may be formed, or the rib may be crushed. In addition, since the viscosity is low even after being extruded, the parison (resin in a semi-molten state) tends to draw down easily, and tends to be difficult to form into a perfect circular tube.

Usually, even if the apparent viscosity of the resin is less than 1000 poise, the apparent viscosity can be reduced to 1000 poise by blending calcium carbonate or the like in the resin or by utilizing chemical crosslinking with a silane coupling agent or the like. The above can be adjusted. Although the spiral groove is not particularly limited, it is preferable that the spiral groove is gradually deeper (the ridge is gradually higher) toward the outlet side of the core. In addition, the pitch of the spiral groove or ridge greatly depends on the extrusion speed in the tube axis direction and the melt viscosity of the resin. The pitch of the ridges should be reduced.

The pitch of the spiral rib or spiral groove is set to 1
00, the spiral pitch of the grooves or ridges should be 35
It is preferable to set it to about 65. Then, as the plasticizing ability of the extruder increases and the extrusion speed increases, the pitch of the grooves or ridges may be made closer to 35. Further, the cross-sectional shape of the concave groove or the ridge is not particularly limited, and includes, for example, a substantially V shape, a substantially U shape, a substantially semicircular shape, and the like, and the depth (or height) thereof may be appropriate. It is preferably about 1/20 to 1/50 with respect to the inner diameter of the pipe.
About 25/1/35 is particularly preferable.

On the other hand, the number of spiral ribs or spiral grooves differs depending on the setting of the limit level of the drainage capacity, and may be one or plural. However, in the case of a pipe having an inner diameter of 80 to 200 mm, the number is 8 to 200. It is preferable to arrange the fibrous lines evenly in the circumferential direction. The material of the ring-shaped member is not particularly limited, but is preferably a steel plate or a synthetic resin plate. The inner diameter of the ring-shaped member is 100% or less of the outer diameter of the tube passing through the ring.
It is preferably about 105%, particularly preferably about 101% to 103%.

It is preferable that the ring-shaped member is divided into two or more arc-shaped divided pieces, and the divided pieces are assembled. Further, it is preferable that the ring-shaped member is provided behind (at the side of the take-up machine) a position where the tube shaped by the forming means is sufficiently cooled and solidified, and a plurality of ring-shaped members may be provided continuously in the tube extrusion direction. Absent.

[0018]

According to the above construction, the parison which is continuously extruded from the mold at a predetermined speed in the tube axis direction and simultaneously extruded while rotating in the circumferential direction along the spiral shape of the spiral rib or the spiral groove is formed. Into the forming means of the forming apparatus, is shaped so as to have a desired outer diameter, is cooled by the cooling means and solidifies to form a desired inner spiral rib or grooved tube, and this tube has a parison extrusion speed. And it is taken by a take-off machine while spirally rotating in synchronization with the rotation speed.

Moreover, since the forming means itself is rotatable, the forming means also rotates with the rotation of the parison, so that the forming can be performed smoothly without difficulty. Since the tube formed by the forming means is received by the ring-shaped member, the tube bends downward and is taken by the take-up machine without bending.

[0020]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 1 shows an extrusion molding apparatus used to carry out the extrusion molding method according to the present invention. As shown in the figure, this extrusion molding apparatus A
An extruder 1, a mold 2, a forming device 3, a take-off device 4, and a cutter 6 are provided.

The mold 2 has substantially the same structure as a normal pipe molding mold, and as shown in FIG. 2, a breaker plate 21, an adapter 22, a rear portion 23, a torpedo 24,
It comprises a bridge 25, a core 26, and a land 27. The clearance of the molten resin passage portion 29 formed between the core 26 and the land 27 is gradually narrower than the bridge 25 in the extrusion direction.
A core parallel portion (core tip portion) 26a is provided at the tip of No. 6.

The core 26 has a spiral groove 2 having a V-shaped cross section on the surface from the core inclined portion 26b to the core parallel portion 26a.
8 are formed at equal intervals, and the core parallel portion 26a has substantially the same diameter over the entire length except for the portion of the spiral groove 28. The land 27 and the core parallel part 2
The gap with 6a is parallel to the tube axis (the center line of the mold 2).

As shown in FIGS. 3 and 4, the forming apparatus 3 includes a forming plate section 31 as forming means, and a first cooling water tank 32 and a second cooling water tank 33 as cooling means. As shown in FIG. 5, the forming plate unit 31 rotates a plurality of sets (three sets in the figure, but preferably as many as possible) and the forming plate groups 34 in the circumferential direction of the parison 5a. And a bearing 35 for supporting freely.

Each forming plate group 34 is composed of a plurality of donut-shaped disks 36. The inner diameter of each donut-shaped disk 36 gradually decreases from the mold 2 side toward the take-up machine 4 side. In addition,
The donut-shaped disk 36 closest to the mold 2 has an inner diameter slightly larger than the outer diameter of the parison 5 a extruded from the mold 2, and the donut-shaped disk 36 closest to the take-up machine 4.
Has an inner diameter substantially the same as the outer diameter of the tube 5b to be manufactured.

As shown in FIG. 5, the first water tank 32 has a forming plate portion 31 incorporated in an inlet portion thereof so that cooling water can be sprayed from a cooling water pipe 37 in a mist state, and a vacuum pump (not shown). ), The cooling water is discharged from the vacuum pipe 38 connected to the first cooling water tank 32, and the air in the first cooling water tank 32 is exhausted at the same time.
The pressure can be reduced to 100 mmHg or less. It has a structure and a structure for draining while reducing the pressure in the tank to -100 mmHg or less. The first cooling water tank 32 is connected to an outlet of the pipe 5b in order to maintain the reduced pressure in the first cooling water tank 32. Are sealed by a rubber packing 39.

Further, the ring-shaped member 8 is screwed on the inner wall surface 32a of the first cooling water tank 32 around the rubber packing 39.
.. 8a. As shown in FIG. 6, the ring-shaped member 8 is formed by combining two half-donut-shaped divided pieces 81, 81.
Note that the normal internal pressure during operation of the first cooling water tank 32 is −
It is preferably about 100 to -300 mmHg, and if it is less than -700 mmHg, there is a high possibility that the rotational force of the parison will be blocked.

On the other hand, the second water tank 33 is provided to compensate for insufficient cooling due to an increase in the amount of extrusion.
It does not need to be provided that cooling can be sufficiently achieved only by using only the above. Further, the take-off machine 4 can take out the pipe 5b in synchronization with the extrusion speed of the parison 5a from the mold 2 in the tube axis direction and the rotation speed of the parison 5a by extrusion. That is, the take-up speed of the tube 5b in the tube axis direction and the speed of rotating the tube 5b at a predetermined speed in the circumferential direction can be freely set.

Therefore, the molten resin 11 sent from the extruder 1 to the mold 2 is extruded from the mold 2 through the molten resin passage 29 formed between the core 26 and the land 27. Since the spiral groove 28 is formed on the surface of the outlet side (from the inclined portion 26b to the parallel portion 26a), the parison 5a extruded from the mold 2 is extruded in the tube axis direction at a predetermined extrusion speed, and is internally spiraled. While being formed with spiral ribs corresponding to the grooves 28, they are rotated and pushed in the circumferential direction. That is, as in the conventional case, parison 5
A spiral rib is formed on the inner surface at the same time as the portion 2 is extruded from the mold 2 in a flowing state without adding a twist.

The extruded parison 5a immediately enters the forming part 3, passes through the forming plate part 31, is shaped into a desired outer diameter, and has a first water tank 32.
And it is cooled and hardened in the second water tank 33. That is, in the forming plate portion 31, the donut-shaped disks 36 continuously arranged gradually decrease in diameter from the mold 2 side toward the take-up machine side.
The parison 5a passing through the inside is gradually narrowed to a small diameter and shaped into a desired outer diameter.

In addition, each forming plate group 34
Are rotatably supported by the bearings 35, so that the forming plate group 34 also rotates smoothly as the parison 5a rotates. Therefore, when the parison 5a passes through the forming plate portion 31, a large frictional resistance does not occur between the surface of the parison 5a and the inner peripheral surface of the disk 36, and the parison 5a is
Since the outer peripheral portion of the parison 5a is not clogged by being caught in step 1, the continuous productivity is extremely high.

Further, the pipe 5b obtained by shaping, cooling and solidifying in this manner is controlled by the take-up machine 4 to the extrusion speed of the parison 5a from the mold 2 in the tube axis direction and the rotation speed of the barison 5a by extrusion. It is designed to be picked up at a synchronized picking-up speed. Then, the pipe 5b taken by the take-up machine 4 is cut into a predetermined length by the cutting machine 6.

That is, according to the method of the present embodiment, since no forced torsion is applied to the parison 5a unlike the prior art, there is no distortion inside and outside the tube 5b,
As shown in FIG. 8, a synthetic resin tube 5b with inner spiral ribs having 12 spiral ribs 51 formed on the inner surface can be obtained. In addition, since the frictional resistance does not greatly apply to the surface of the parison 5a in the forming plate portion 31, the outer peripheral portion of the parison 5a is not clogged by the forming plate portion 31. Therefore, continuous production can be performed.

Further, the tube 5b shaped in the forming plate portion 31 is cooled and solidified with cooling water,
Since the tube 5b is received by the take-up machine 4 while being received by the inner peripheral surface of the ring-shaped member 8 provided at the outlet, it does not bend downward, and the finished tube 5b is of high commercial value with almost no bending. become. Hereinafter, more specific examples will be described together with comparative examples.

(Example 1) The outer diameter of the pipe 5b to be manufactured was 11
The minimum diameter of the donut-shaped disk 36, that is, the inner diameter of the donut-shaped disk 36 closest to the take-off machine 4 is set to 11 so that the diameter is 11 mm.
0 mm and the inner diameter of the ring-shaped member 8 is 1 mm.
A split of 11.2mm as shown in Figure 6, and
A rubber packing 39 having an inner diameter of 80 mm, a thickness of 3 mm, and a Shore A hardness of 55 was used. The extrusion speed was 1 m / min, the rotational take-off speed was 2 rpm, the vacuum pressure was -250 mmHg, and the water spray amount was 5
When a vinyl chloride tube 5b with an inner spiral rib having a thickness of 2 mm and a rib thickness of 5 mm was manufactured under the manufacturing conditions of 0 liter / minute and a water temperature of 16 ° C., the maximum value of the bending of the completed tube 5b was 0.4 mm. .

The ring-shaped member 8 is formed by an extruder A
After the start of the operation, one end of the formed pipe 5b reaches the take-up machine 4, and the parison 5a is supplied stably. Then, as shown in FIG. 32a.

(Comparative Example 1) Except that the ring-shaped member was not attached, a vinyl chloride tube 5b with an inner spiral rib was extruded in the same manner as in Example 1, and the maximum value of the bending of the completed tube 5b was 5 mm. there were.

The method of manufacturing the synthetic resin tube having the spiral spiral ribs according to the present invention is not limited to the above embodiment. For example, in the above embodiment, after the operation of the extrusion apparatus A is started, one end of the formed tube 5b is connected to the take-up machine 4 in the ring-shaped member 8.
After the parison 5a is supplied stably, the parison 5a is fixed to the inner wall surface 32a of the first cooling water tank 32, but may be fixed in advance. In the case where the ring-shaped member 8 is fixed in advance, it is not necessary that the ring-shaped member 8 can be divided.

Further, in the above embodiment, a plurality of donut-shaped disks are set as a set and rotatably supported by one bearing. However, only one disk is supported by one bearing. No problem. In the above embodiment, the spiral groove is formed from the inclined portion of the core to the parallel portion. However, the spiral groove may be provided only in the parallel portion.

[0039]

According to the present invention, since the method for extrusion molding a synthetic resin pipe with internal spiral ribs or grooves according to the present invention is constructed as described above, deformation such as twisting occurs after piping, or hot drainage flowing inside. The spiral rib does not become smaller due to the influence of, and the drainage capacity is not semi-permanently impaired, and the inner spiral rib or grooved synthetic resin pipe having no bending and good appearance and high commercial value is obtained. be able to.

Therefore, if this synthetic resin pipe is used as a vertical pipe for drainage of a building such as a middle-rise or high-rise building, the ability to effectively attenuate the flow rate of drainage and ensure sufficient ventilation in the center of the pipe is semi-permanent. Not be impaired. In addition, since the synthetic resin pipe is straight without bending, it can be very easily inserted into the steel pipe even when used as an inner pipe of the lining steel pipe.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example of an extrusion molding apparatus used for carrying out a method of manufacturing a synthetic resin tube having an internal spiral rib according to the present invention.

FIG. 2 is a sectional view showing an extrusion die portion of the extrusion molding apparatus of FIG.

FIG. 3 is a front view of a forming device of the extrusion molding device of FIG. 1;

FIG. 4 is a side view of a forming device of the extrusion molding device of FIG.

5 is a half sectional view showing a first cooling water tank part of the forming apparatus of FIG. 3;

FIG. 6 is an explanatory view showing a state where a ring-shaped member is attached.

FIG. 7 is a perspective view showing an embodiment of a synthetic resin tube with an internal spiral rib obtained by the method for manufacturing a synthetic resin tube with an internal spiral rib according to the present invention.

FIG. 8 is a cross-sectional view of the synthetic resin tube with an inner spiral rib of FIG. 3;

FIG. 9 is a longitudinal sectional view of the synthetic resin pipe with an inner spiral rib shown in FIG. 3;

FIG. 10 is an explanatory view showing a method of manufacturing a known synthetic resin tube having an internal spiral rib.

FIG. 11 is a half sectional view showing a forming device part of the extrusion molding method previously proposed by the inventor of the present invention.

[Explanation of symbols]

 Reference Signs List 2 extrusion die 3 forming device 8 ring-shaped member 5a parison 5b pipe 31 forming plate section (forming means) 32 first cooling water tank (cooling means) 33 second cooling water tank (cooling means) 51 spiral rib

Continuation of front page (56) References JP-A-59-187418 (JP, A) JP-A-5-293909 (JP, A) JP-A-48-86964 (JP, A) JP-A-5-293873 (JP) JP-A-63-260420 (JP, A) JP-A-55-67419 (JP, A) JP-A-5-309718 (JP, A) JP-A-6-143386 (JP, A) 56-76420 (JP, U) JP 49-42670 (JP, B1)

Claims (1)

(57) [Claims] 1. A method in which a parison having a spiral rib or groove formed on its inner surface is continuously extruded from an extrusion die while being spirally rotated, and the extruded parison is formed with a forming means and a cooling means rotatable in a circumferential direction. Cooling and solidifying while shaping into a tube of the desired outer diameter through a forming device provided,
Further, there is provided a method for extruding an inner spiral rib or a grooved synthetic resin tube for drawing the tube at a speed synchronized with the extrusion speed and the rotation speed of the parison, wherein the outer diameter of the tube is substantially equal to the outer diameter of the tube shaped by the forming means. At least one ring-shaped member made of a hard material having the same or a slightly larger inner diameter is arranged in a forming device behind the forming means, and a pipe shaped by the forming means is passed through the ring-shaped member to form a ring-shaped member. An extruding method of an inner spiral rib or a grooved synthetic resin tube, wherein the tube is received by an inner wall surface of a member.