JPH0473693B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method and an apparatus for molding a synthetic resin pipe having a spiral groove on its inner circumferential surface. More specifically, a method for molding a synthetic resin pipe in which an uneven strip such as a spiral circle or a polygon is formed on the inner circumferential surface;
This invention relates to improvements in the molding machine used directly to carry out this molding method, the molding surface, and the properties of the resulting product (synthetic resin pipe).

(Technical background) A so-called corrugated pipe is a synthetic resin pipe with uneven lines, but the uneven lines are formed integrally on the inner and outer circumferential surfaces, which causes a problem that it lacks pressure resistance and is easily damaged by external pressure. .

On the other hand, there is a demand for the development of synthetic resin pipes with excellent pressure resistance and flexibility in order to protect the wiring of cables such as electric wires and optical fibers. A synthetic resin pipe is provided.

(Prior art and its problems) Conventionally, as a means of manufacturing a synthetic resin pipe in which spiral uneven stripes are formed only on the inner circumferential surface, for example, a flexible tape-shaped resin band is formed along the longitudinal direction of one side of the pipe. It is known that a tape-shaped resin band made by bonding a rigid reinforcing wire is wound so that a portion of the edge of the tape-like resin band overlaps with the reinforcing wire inside, and the overlapping portion is welded.

According to such conventional manufacturing means, there is a problem in that the manufacturing process such as molding, adhesion, winding, and welding of the tape-shaped resin band and the reinforcing wire rod is time-consuming and the manufacturing cost increases.

In addition, it is difficult to manage the dimensional accuracy of the pitch and depth of the irregularities, and to select and adjust the dimensions, making it impossible to obtain a structure with flexible dimensions.

Furthermore, synthetic resin pipes manufactured by such conventional manufacturing methods have low durability, such as tape-shaped resin bands and reinforcing wires coming off due to the effects of tensile force, torsional force, compressive force, etc. There is.

In addition, as a general method for manufacturing synthetic resin pipes, it is known that a tubular molten resin extruded from an extruder equipped with an extrusion mold is stretched and cooled and hardened.

(Objective of the Invention) The present invention has been made to solve the above-mentioned problems, and its purpose is to provide a synthetic resin that can be manufactured in a structure with flexible dimensions, reduces manufacturing cost, and It is an object of the present invention to provide a method for molding a synthetic resin pipe having spiral unevenness on the inner circumferential surface, which improves the durability of the pipe. A further object of the present invention is to provide a synthetic resin pipe molding apparatus having a spiral concavo-convex strip on its inner circumferential surface, which is suitable for direct use in carrying out this molding method.

(Structure of the Invention) In order to achieve the above-mentioned object, the method for molding a synthetic resin pipe having a spiral unevenness on the inner circumferential surface according to the present invention is a method for forming a synthetic resin pipe having a spiral groove on the inner circumferential surface. In a method for forming synthetic resin tubes in which a molten resin is stretched and cooled and hardened, a shaping roll whose axis can be freely adjusted at an angle with respect to the axis of a tubular molten resin is extruded and pulled inside an extrusion die. The structure is characterized in that the resin is made to revolve while being pressed against the inner circumferential surface of a tubular molten resin, a spiral uneven strip is formed on the inner circumferential surface of the tubular molten resin, and the resin is cooled and hardened.

Further, the apparatus for molding a synthetic resin pipe having spiral unevenness on the inner circumferential surface according to the present invention includes an extruder equipped with an extrusion mold from which a tubular molten resin is extruded, and a molten resin extruded from the extruder. In a synthetic resin tube forming device that consists of a winder that pulls the resin, and a cooler installed between the extruder and winder that cools and hardens the molten resin, the molten resin is installed inside the extrusion mold to form a tubular molten resin. a shaping roll that presses into contact with the inner circumferential surface of the molten resin; a drive mechanism that makes the shaping roll revolve within the inner circumferential surface while maintaining the press contact state; and a variable angle of the axis of the shaping roll with respect to the axis of the tubular molten resin. The present invention adopts a configuration characterized in that it is equipped with a concavo-convex line forming means consisting of a variable mechanism.

(Function) In the above-mentioned configuration, rotating the shaping roll while pressing against the inner peripheral surface of the tubular molten resin inside the extrusion die means that the shaping roll is pressed against the inner peripheral surface of the tubular molten resin and rotates around it. To achieve the purpose of reducing manufacturing costs by reducing manufacturing effort by forming spiral uneven stripes. Furthermore, by making the angle of the axis of the shaping roll adjustable with respect to the axis of the tubular molten resin, it is possible to freely adjust the pitch, depth, etc. of the uneven stripes by adjusting the speed of extrusion and pulling of the molten resin. Achieve the purpose of enabling manufacturing.

Furthermore, the uneven stripes are integrally formed by a shaping roll that presses into contact with the inner circumferential surface of the molten resin, thereby achieving the purpose of preventing detachment of the uneven strips and improving durability.

(Example) Hereinafter, an example of a method for molding a synthetic resin pipe having a spiral unevenness on its inner circumferential surface and an apparatus therefor according to the present invention will be described with reference to the drawings.

FIG. 1 shows an extruder 1 constituting the main part of the molding means of the present invention.
Cylindrical nipple holder 1 fitted and fixed inside the
2, a nipple 13 screwed and fixed to the tip of the nipple holder 12, and an extrusion mold 14 screwed and fixed to the tip of the main body 11 and arranged so as to surround the nipple 13. A cylindrical extrusion passage 15 is formed between the nipple holder 12 and nipple 13, the main body 11, and the extrusion mold 14, and the extrusion mold 14
A cylindrical extrusion passage 16, which is separate from the extrusion passage 15, is also formed inside the extrusion passage 15.

These extrusion passages 15, 16 communicate on the one hand with separate feed ports 17, 18, respectively, and on the other hand, they merge near the tip of the nipple 13.

In such an extruder 1, as shown in FIG. 4, molten resins A and B are supplied from supply ports 17 and 18, respectively, and merge near the tip of the nipple 13 in the extrusion mold 14, forming a two-layered tubular shape. It is extruded from the extrusion die 14. Then, extruded tubular molten resins A and B
is pulled and wound up by a winder (also not shown) via a cooler such as a water tank (not shown).

In the extruder 1 described above, a shaping roll 2 is installed inside the extrusion die 14 outside the tip of the nipple 13. This shaping roll 2 consists of a roll part 21 having an uneven surface such as a circle or a polygon, and a spindle 22 having one end axially aligned with the roll part 21 and the other end inserted into the nipple 13.

Furthermore, a drive mechanism 3 is provided for this shaping roll 2.
and a variable mechanism 4 are attached, and the shaping roll 2, drive mechanism 3, and variable mechanism 4 constitute an uneven strip forming means P.

The drive mechanism 3 includes a rotary cylinder 3 having a rear end fixed to a pulley 32 rotated by a V-belt 31 with bolts, and a distal end disposed inside the nipple holder 12.
3, two bearings 34 and 35 which are interposed between the rotary tube 33 and the nipple holder 12 and rotatably support the rotary tube 33; spindle 2
a shaft 37 equipped with a spindle holder 36 that removably holds the shaft 3; and a balancer 3 that is fitted and attached to the shaft 37 to prevent vibration of the shaft 37.
It consists of 8.

The variable mechanism 4 includes a spherical part 41 provided near the center of the shaft 37, and a spherical seat 42 provided on the inner surface of the rotary cylinder 33 to support the spherical part 41.
A pin 43 fixed to the rear end of the shaft 37, a reaction body 45 that has an oblique groove 44 that engages with the pin 43 and slides inside the rotating cylinder 33, and a reaction body 45 that moves the sliding movement of the reaction body 45 to the outside of the rotating cylinder 33. The operating shaft 4 connects the operating screw 46 that is operated from the rear, the responsive body 45, and the operating screw 46.
7, a spring 48 for smoothly operating the operating shaft 47, and a stopper 49 for regulating the operating range of the operating shaft 47.

In such an uneven strip forming means P, the operating screw 4
When 6 is rotated, the position of the pin 43 engaged in the groove 44 is changed by the sliding of the operating shaft 47 and the responsive body 45, as is clear from the comparison between FIGS. 1 and 2. . The position of this pin 43 can be changed by
The shaft 37 to which the pin 43 is fixed is tilted using the spherical portion 41 and the spherical seat 42 as fulcrums. That is, the angle of the axis of the shaping roll 2 with respect to the axis of the tubular molten resins A and B formed by the extrusion die 14 is varied.

If this angle is made large, the range in which the roll portion 21 of the shaping roll 2 is pressed into contact with the inner circumferential surface of the tubular molten resins A and B becomes large. When the drive mechanism 3 is driven by the V-belt 31, the roll portion 21 of the shaping roll 2 revolves while being pressed against the inner circumferential surfaces of the tubular molten resins A and B. G is formed, but the molten resins A and B are extrusion mold 1.
The uneven strip G is extruded from 4 and pulled by the winder.
becomes a spiral. In addition, since the roll part 21 of the shaping roll 2 revolves inside the extrusion mold 14, the outside of the molten resins A and B is pressed by the extrusion mold 14, and the uneven stripes G are formed up to the outside of the molten resin A and B. It will not be done.

The formation of such uneven stripes G is performed integrally with the shaping work of the synthetic resin pipe, so that the work does not take much time. In addition, the depth of the groove of the uneven strip G can be adjusted by operating the variable mechanism 4, and the groove of the uneven strip G can be adjusted by adjusting the extrusion pulling speed of the molten resins A and B and replacing the shaping roll 2 to the spindle holder 36. By replacing the shaping roll 2 with the spindle holder 36, the shape of the groove of the uneven strip G can be adjusted. In particular, the variable mechanism 4 can be operated even while the extruder 1 is in operation, allowing fine adjustment during the molding process.

The synthetic resin pipe formed in this manner and having the spiral grooves G on the inner circumferential surface cannot come off because the grooves G are integrally formed with the synthetic resin pipe. Note that the extruder 1 may be one that molds a single layer of molten resin, but when molding two layers of molten resin A and B as shown in the figure, for example, the outer molten resin B is a soft material and the inner molten resin is a soft material. When the molten resin A is used as a hard material and the uneven stripes G are formed on the hard material, there is an advantage that a synthetic resin pipe with extremely good flexibility can be obtained.

(Effects of the Invention) As described above, in the method for molding a synthetic resin pipe having spiral uneven stripes on the inner circumferential surface according to the present invention, the uneven stripes are fabricated integrally with the molding process of the synthetic resin pipe. This has the effect of reducing manufacturing costs without requiring much manufacturing effort. Furthermore, the machining of the uneven stripes has the effect of allowing the dimensional structure such as the pitch of the grooves to be set freely.
In addition, in a synthetic resin pipe manufactured by this molding method and having a spiral concavo-convex strip on its inner circumferential surface, detachment of the concave-convex strip does not occur and the durability is improved.

Furthermore, the apparatus for molding a synthetic resin pipe having a spiral uneven strip on the inner circumferential surface according to the present invention has the same effect as the molding method described above, and also can be formed even when the extruder is operating due to the installation structure of the movable mechanism. This has the effect of making it possible to finely adjust the uneven stripes.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an embodiment of a molding apparatus for a synthetic resin pipe having a spiral uneven strip on the inner circumferential surface according to the present invention, and FIG. 3 is a sectional view taken along the Y-Y line in FIG. 1, FIG. 4 is a sectional view showing the operating state of FIG. 1, and FIG. 5 is a sectional view taken along the Z-Z line in FIG. 4. 1... Extruder, 2... Shaping roll, 3... Drive mechanism, 4... Variable mechanism, 14... Extrusion die, A, B
... Molten resin, G... Uneven strip, P... Uneven strip forming means.

Claims (1)

[Scope of Claims] 1. A method for forming a synthetic resin pipe in which a tubular molten resin extruded from an extruder equipped with an extrusion die is stretched and cooled and hardened, wherein the tubular molten resin is extruded inside the extrusion die. A shaping roll whose axis can be freely adjusted at an angle with respect to the axis of 1. A method for forming a synthetic resin pipe having spiral grooves on its inner circumferential surface, the method comprising forming a synthetic resin pipe and then cooling and hardening it. 2. An extruder equipped with an extrusion die through which tubular molten resin is extruded, a winder that pulls the molten resin extruded from the extruder, and a winder installed between the extruder and the winder to cool and harden the molten resin. A molding device for a synthetic resin pipe, which comprises a cooling machine for forming a synthetic resin tube, a shaping roll provided inside an extrusion die and pressed against the inner circumferential surface of the tubular molten resin; The invention is characterized in that it is equipped with an uneven strip forming means consisting of a drive mechanism that revolves in the plane and a variable mechanism that changes the angle of the axis of the shaping roll with respect to the axis of the tubular molten resin. A molding device for synthetic resin pipes with uneven stripes.