JPH06170925A - Changing method of color and material for alow molding machine - Google Patents

Abstract

PURPOSE:To realize shortening of a molding cycle, by a method wherein reten tion resin is separated from a retention position by applying an ultrasonic oscilla tion to retention resin in a resin passage between a die head and mandrel and the same is extruded and removed through supply of fresh resin. CONSTITUTION:In the case where a resin hollow product is manufactured by a blow molding machine 1, high-temperature molten resin pressed by an extruding machine 4 is moved to the lower part almost evenly to the circumference by passing through a gap among a mandrel 3, core 3a and a die head 2 through a resin supply port 2a, discharged through an annular space passage 7 and a parison P is formed. An ultrasonic oscillator 10 is provided on a part where resin is apt to retain such as the vicinity of a confluent point between a resin passage and the die head 2 provided on the mandrel 3 at a manufacturing time like this and an exchange time of colors or materials wherein it is apt to incur deterioration of resin and requires time. The method is constituted so that resonance is applied to the retention resin by a generated ultrasonic wave, separated from a retention position and the same is extruded and removed by fresh resin supply.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color changing / material changing method of a blow molding machine for producing a hollow product from a parison, and particularly a simple color changing / material which does not require troublesome disassembly and cleaning of a die. Regarding replacement method.

[0002]

2. Description of the Related Art In blow molding in which a hollow resin product is made from a parison that is cylindrically injected or extruded from a die head, a parison is injected or extruded from the die head and pre-blown into a bag-shaped parison by a parison pinch. After inflating slightly, put it in an open mold and close the mold, and after degassing the gas in the cavity formed by the mold and parison, a vacuum pump device from a small air vent hole leading to the mold surface After suctioning air through the, the parison is blown into the parison with high pressure to form the parison into a predetermined shape based on the cavity and then cooled with a die to complete the molding. The resin product thus molded is taken out by opening the mold.

[0003]

In the blow molding described above, the method of changing the color of the material resin and the method of changing the material resin are the same as those of the conventional method by flowing a new resin into the resin supply passage provided in the die head. Although a method of expelling the resin and destroying it is used, the resin tends to stay at the confluence of the die head supply passage and the annular passage between the die head and the mandrel, and resin replacement is poor. Therefore, a valve or plug is installed near this confluence point to connect to the outer periphery of the die head, and when changing the resin, this valve can be opened to the closed state or the plug can be removed to completely discharge the previous resin. Although a method was attempted, the stagnant resin could not be completely removed. Therefore, when exchanging the resin, the die itself was completely disassembled to clean the inside, but this was troublesome.

[0004]

[Means for Solving the Problems] In order to solve such problems and perform color change and material change easily and completely without disassembling and cleaning the die, in the method of the present invention, In a blow molding machine in which a parison discharged from a resin passage between a die head and a mandrel is sandwiched by a pair of left and right dies to make a hollow product, ultrasonic waves are applied to the resin retained in the resin passage to cause retention. By causing the resin to resonate, the resin is separated from the staying point, and the stagnant resin is discharged by the resin flow from the upstream of the staying point.

[0005]

In the method of color change / material change in the blow molding machine of the present invention, the resin that stays in the annular passage is subjected to ultrasonic vibration to break the adhesion with the die, and the new resin is extruded and removed. To do. As a result, the molding cycle can be shortened without disassembling and cleaning the die, which is particularly suitable for high-mix low-volume production and improves productivity.

[0006]

Embodiments of the present invention will now be described in detail with reference to the drawings. 1 to 4 relate to an embodiment of the present invention,
1 is a vertical sectional view of the die head, FIG. 2 is a plan view of the die head of FIG. 1, FIG. 3 is a vertical sectional view of another embodiment of the die head, and FIG. 4 is a plan view of the die head of FIG. is there.
1 and 2 show a so-called side-feed type blow molding machine 1 in which molten resin is supplied from one side of the die head 2. The resin in a high-temperature molten state pressed by an extruder 4 is a resin supply port. The parison P is formed by being discharged from the lowermost annular space passage 7 through an annular passage provided between the die head 2 and the mandrel 3 via 2a.
A passage 2b and a valve 5 (or a plug) provided outside the passage 2b are arranged at a position 180 ° away from the resin supply port 2a of the die head 2, and the valve 5 is inclined about 30 ° around the center distribution. A plurality of ultrasonic transducers 10 are attached to the vibration probe 10a, and the vibration probe 10a is projected inside through a through hole provided in the die head 2. The core 3a is connected to a Parison rod 6a penetrating the mandrel 3, and is slightly moved in the vertical direction by the operation of the Parison cylinder 6, and the annular space passage 7 is used to control the wall thickness of the parison P.
The gap can be adjusted.

On the other hand, what is shown in FIGS. 3 and 4 is called a center feed system, and a resin supply path extending downward through the central axis of the mandrel 3 is branched in the middle of the mandrel 3 into left and right parts, and the peripheral parts are respectively formed. The groove 3A is formed in the mandrel 3 so that the supplied resin flows down toward the circumference evenly.
And, in the die head 2 near the tip of the groove 3A,
A horizontal passage 2b and a valve 5 (or plug) attached to the outside thereof are arranged. Further, as in the case of FIG. 1 and FIG. 2, a plurality of pairs of ultrasonic transducers 10 are attached at a position inclined by about 30 ° with the valve 5 as the central distribution, and the vibration probe 10a of the ultrasonic transducer 10 is a die. It protrudes inward through a through hole provided in the head 2, and its tip has a groove 3A.
Reach

The operation of the blow molding machine 1 of the type shown in FIGS. 1 to 2 or 3 to 4 constructed as above will be described. The high temperature molten resin pressed by the extruder 4 flows down through the resin supply port 2a through the groove 3A provided in the mandrel 3, the gap between the mandrel 3 or the core 3a and the die head 2, and moves downward substantially evenly around the circumference. Then, the parison P is formed by being discharged from the lowermost annular space passage 7. However, in the vicinity of the confluence point between the resin passage provided in the mandrel 3 and the die head 2, that is, slightly above the passage 2b at the position where the valve 5 is arranged, the resin is liable to cause a vortex flow, so that the resin stays and color As a result of requiring a long time for replacement and material replacement, the molten resin deteriorates, a weld line is formed in the molded product, and the quality deteriorates. In the present invention, as a countermeasure against this, at the time of color change or material change, the ultrasonic vibrator 10 provided at a place where resin retention is likely to occur is energized to give ultrasonic waves to the retained resin to cause resonance, and the mandrel 3 The stagnant resin is removed by pressing the new resin and removing it from the die head 2. At this time,
In order to facilitate the discharge of these accumulated resins, the valve 5 is opened to assist the discharge. In this way, when the ultrasonic vibrator 10 is used to separate the stagnant resin from the main body by vibration at the time of color change / material change, color change or material change can be performed relatively easily without disassembling and cleaning the die. Can be implemented.

[0009]

As described above, according to the color changing / material changing method in the blow molding machine of the present invention, since the color changing and the material changing can be carried out in a short time, the disassembling / cleaning of the die becomes unnecessary and the maintainability is improved. In addition, the molding cycle is shortened and the productivity is improved. In addition, cost reduction can be achieved by reducing the color-changing resin, and the productivity will be significantly improved especially in a factory for high-mix low-volume production.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of a main part of a blow molding machine according to an embodiment of the present invention.

FIG. 2 is a cross-sectional plan view of the blow molding machine of FIG.

FIG. 3 is a longitudinal sectional view of a main part of a blow molding machine according to another embodiment of the present invention.

4 is a cross-sectional plan view of the blow molding machine of FIG.

[Explanation of symbols]

 1 Blow Molding Machine 2 Dice Head 2a Resin Supply Port 2b Passage 3 Mandrel 3a Core 3A Groove 4 Extruder 5 Valve 6 Paricon Cylinder 6a Paricon Rod 7 Annular Space Passage 10 Ultrasonic Transducer 10a Vibration Probe

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location B29C 49/72 6122-4F // B29L 22:00 4F

Claims (1)

[Claims] 1. A blow molding machine in which a parison discharged from a resin passage between a die head and a mandrel is sandwiched by a pair of left and right dies to form a hollow product, and ultrasonic waves are applied to the resin retained in the resin passage. A color changing / material changing method in a blow molding machine in which vibration is applied to cause the staying resin to resonate so that the staying resin is separated from the staying point and the staying resin is discharged by a resin flow from the upstream of the staying point.