JP2007112090A - Apparatus for manufacturing resin tube - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for manufacturing a resin tube for preventing an air bubble floating in cooling water from sticking to the surface of a parison in a parison cooling process. <P>SOLUTION: The apparatus for manufacturing a resin tube comprises supplying a molten resin extruded from an extruder into a die 2, introducing a parison P extruded from the die 2 into a cooling water tank 3 keeping a forming tube 31 disposed at the inlet thereof and a plurality of size-adjusting spacers 32 disposed inside, and cooling the parison P, and manufacturing a resin tube having a predetermined size, wherein a shower ring 4 having a plurality of spout holes formed spaced apart on the inner circumference surface thereof, is disposed between the forming tube 31 and the size-adjusting spacers 32, and the cooling water is supplied toward the parison P passing through the shower ring 4 from each of the spout holes. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an apparatus for manufacturing a resin pipe such as a polyethylene pipe.

Conventionally, a resin tube has been supplied with molten resin extruded from an extruder into a mold, a parison extruded from the mold is provided with a forming tube at the inlet, and a plurality of dimension adjusting spacers are disposed therein. It is manufactured to a predetermined size by being led to a provided cooling water tank and cooled (for example, see Patent Documents 1 and 2).
JP 2001-150517 A Japanese Patent Laid-Open No. 2001-170992

  By the way, in the cooling process of the resin pipe, the cooling water is circulated between the cooling water tank and the cooling device, and the cooling water in the cooling water tank is always maintained at a constant temperature, for example, 8 to 10 ° C. and pushed out of the mold. The parison is cooled.

  In this case, air is mixed in the cooling water, and when cooling water is supplied to the cooling water tank, it is ejected as bubbles. Further, when the cooling water is warmed by the high-temperature parison, the air dissolved in the cooling water evaporates and rises into the cooling water as bubbles. When air bubbles floating in the cooling water adhere to the parison in the cooling process in this way, a difference occurs in the cooling rate of the parison, that is, the shrinkage rate between the portion where the air bubbles (air) adhere and the portion where the air bubbles do not adhere. There was a problem that crater-like irregularities were formed on the surface of the produced resin tube.

  The present invention has been made in view of such problems, and provides a resin pipe manufacturing apparatus capable of preventing bubbles floating in cooling water from adhering to the surface of the parison during the parison cooling process. To do.

  The present invention supplies a molten resin extruded from an extruder to a mold, a parison extruded from the mold, a cooling tube provided with a forming tube at an inlet, and a plurality of dimension adjusting spacers disposed therein. In a resin pipe manufacturing apparatus that guides and cools a water tank to manufacture a resin pipe of a predetermined size, a plurality of ejection holes are formed between the forming tube and the dimension adjusting spacer at intervals on the inner peripheral surface. One or a plurality of shower rings are provided, and cooling water is supplied from the ejection holes toward the parison passing through the shower rings.

  According to the present invention, the parison extruded from the mold passes through the forming tube so that the outer diameter is regulated and guided to the cooling water tank, and cooling is started. Next, the parison is guided to the shower ring, and when passing through the shower ring, cooling water is supplied toward the parison from the ejection hole. Thereafter, the parison passes through the dimension adjusting spacer and continues to be cooled, and is formed into a resin pipe having a predetermined dimension.

  As a result, when the parison passes through the shower ring, the cooling water is supplied to the outer peripheral surface thereof, so that the parison immediately after passing through the forming tube can be quickly cooled and the air bubbles floating in the cooling water Can be swept away from the surface of the parison.

  Here, it has been found that when the parison is cooled to 150 ° C. or lower, even if bubbles adhere to the surface of the parison, the molded resin tube does not generate irregularities. An appropriate number of shower rings may be provided until the parison is cooled to 150 ° C. or lower according to conditions such as the wall thickness and the take-off speed.

  In the present invention, the shower ring has a tapered surface tapered toward the outlet side on the inlet side of the parison, and a plurality of ejection holes are substantially formed in the tapered surface at intervals in the circumferential direction. When formed so as to be orthogonal, the cooling water ejected from the ejection hole becomes a water flow toward the upstream side of the parison, which is the high temperature side, along the outer circumferential surface of the parison, so that the parison is cooled more quickly. In addition, it is possible to more reliably prevent bubbles from adhering.

  ADVANTAGE OF THE INVENTION According to this invention, while being able to cool a parison rapidly, it can prevent that the bubble which floats in cooling water adheres to the surface of a parison.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows an embodiment of a resin pipe manufacturing apparatus 1 according to the present invention.

  The manufacturing apparatus 1 includes an extruder (not shown), a mold 2 that extrudes molten resin supplied from the extruder as a parison, a cooling water tank 3 that cools the parison P extruded from the mold 2, and a cooling water tank 3. And a take-up machine (not shown) for taking up a resin tube molded to a set outer diameter. The inlet of the cooling water tank 3 is provided with a forming tube 31 whose inner diameter is set so as to substantially restrict the outer diameter of the resin pipe to be manufactured, and the inner diameter gradually decreases toward the downstream side inside. The dimension adjusting spacers 32 formed in the above are disposed at set intervals. The cooling water tank 3 is provided with a shower ring 4 located between the forming tube 31 and the dimension adjusting spacer 32 described above.

  As shown in FIG. 2, the shower ring 4 is formed in a ring shape having an insertion hole 4 a having an inner diameter larger than the outer diameter of the parison P extruded from the mold 2, and the forming hole 31 is formed in the insertion hole 4 a. In the vicinity of the opposing inlet side, a tapered surface 4b that is tapered toward the outlet side is formed. In the shower ring 4, a plurality of ejection holes 4x are formed so as to be substantially orthogonal to the tapered surface 4b at a set interval in the circumferential direction on the tapered surface 4b described above, and led to the connecting portion 4c from the outside. The cooling water can be ejected from each ejection hole 4x.

  Next, the operation of the manufacturing apparatus 1 configured as described above will be described.

  First, the cooling water tank 3 is supplied with cooling water cooled to about 8 to 10 ° C. by a cooling means (not shown), and the drainage is sent again to the cooling means to be cooled. It comes to circulate. The shower ring 4 is also branched from a water supply pipe supplied from the cooling means to the cooling water tank 2 and supplied with cooling water through the connecting portion 4c, and is directed from the ejection hole 4x toward the facing forming tube 31 side. Has been erupted.

  The resin is kneaded and melted by an extruder (not shown), supplied to the mold 2, and extruded from the annular resin flow path 2a. Next, the parison P pushed out from the mold 2 passes through the forming tube 31 provided at the inlet of the cooling water tank 3 to be regulated by the outer diameter of the resin pipe to be manufactured, and cooling by the cooling water is started. Is done. Thereafter, when the parison P that has passed through the forming tube 31 is guided to the insertion hole 4 a of the shower ring 4, cooling water is ejected from the respective ejection holes 4 x of the shower ring 4 toward the outer peripheral surface of the parison P. The jetted cooling water is opened along the outer peripheral surface of the parison P by being inclined and opened toward the forming tube 31 facing the jet hole 4x, that is, toward the upstream side of the parison P. The parison P quickly cools and solidifies, and the water flow prevents bubbles that float in the cooling water of the cooling water tank 3 from adhering to the outer peripheral surface of the parison P.

  For example, when the cooling water is supplied to the cooling water tank 3, air mixed in the cooling water becomes bubbles and floats in the cooling water. Further, the parison P immediately after being pushed out from the mold 2 is about 200 ° C., and the parison P just after passing through the forming tube 31 is about 180 ° C. When the cooling water is warmed in contact with the cooling water, Air dissolved in the air rises as bubbles. A water flow is generated along the surface of the parison P so that the bubbles floating in the cooling water do not adhere to the surface of the parison P.

  Next, the parison P that has passed through the shower ring 4 is successively passed through the plurality of dimension adjusting spacers 32, so that cooling is continued by the cooling water and is taken to a prescribed size.

  As a result, when the parison P is guided to the cooling water tank 3 and cooled by the cooling water, the parison P can be quickly cooled and solidified to a temperature at which there is no influence of the adhesion of bubbles, and the bubbles floating in the cooling water can be Can be prevented from adhering to the surface. Therefore, it is possible to reliably manufacture a resin tube having no irregularities on the surface.

  As described above, according to the present invention, it is possible to reliably prevent the occurrence of irregularities due to the bubbles adhering to the parison, so that the defective rate can be reduced and the resin tube can be manufactured efficiently.

It is sectional drawing which abbreviate | omits one Embodiment of the manufacturing apparatus of the resin pipe | tube of this invention, and shows typically. It is a longitudinal cross-sectional view of a shower ring.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Manufacturing apparatus 2 Mold 3 Cooling water tank 31 Forming tube 32 Spacer for dimension adjustment 4 Shower ring 4a Insertion hole 4b Tapered surface 4x Ejection hole

Claims (2)

  The molten resin extruded from the extruder is supplied to the mold, and the parison extruded from the mold is led to a cooling water tank provided with a forming tube at the inlet and provided with a plurality of dimension adjusting spacers inside. In a resin tube manufacturing apparatus that cools and manufactures a resin tube of a predetermined size, one or a plurality of ejection holes are formed between the forming tube and the dimension adjusting spacer at intervals on the inner peripheral surface. An apparatus for manufacturing a resin pipe, comprising a plurality of shower rings and supplying cooling water from an ejection hole toward a parison passing through the shower ring.   The shower ring has a tapered surface tapered toward the outlet side on the inlet side of the parison, and a plurality of ejection holes are substantially orthogonal to the tapered surface at intervals in the circumferential direction of the tapered surface. 2. The resin pipe manufacturing apparatus according to claim 1, wherein the apparatus is formed.

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