JPH0970880A - Blow molding method and device for hollow molded article - Google Patents

Abstract

(57) [Summary] (Correction) [PROBLEMS] A single-layer blow molding machine is used to easily and easily obtain a two-layer hollow blow-molded product which is complicatedly bent in one molding. SOLUTION: In a blow molding method of a hollow molded article,
A pair of left and right dies are formed in a shape having a cavity shape which is three-dimensionally bent when the dies are closed, and a parison is discharged by sucking a gas inside the closed space from a lower portion to form the cavity in the closed space. While being introduced into the inside, while adhering the powder of the resin material or the inorganic material supplied together with the gas from the upper end of the die to the outer surface of the parison during discharging, after the parison reaches a predetermined length. The discharge lowering of the parison is stopped, the upper end of the mold and the lower end of the mold are closed, and the mold cavity surface is previously set to the softening point temperature of the higher of the powder resin material and the parison resin material. After heating to, the mold was clamped and blown.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blow molding method and a blow molding product for molding a hollow molding product in which powder is adhered to the surface of a parison. BLOW MOLDING METHOD AND DEVICE FOR HOLLOW MOLDED PRODUCT, WHICH OBTAINS MOLDED ARTICLE HAVING BENDED SHAPE AND POSITIVELY EASILY DEPOSIT TO POWDER OF HALLOWETY OR DIFFERENT RESIN OR INORGANIC MATERIAL POWDER ON PARISON Is.

[0002]

2. Description of the Related Art In blow molding for producing a hollow resin product from a parison injected or extruded into a cylindrical shape from a die head, a parison is injected or extruded from a die head, and a pre-blow is applied to a parison formed into a bag by a parison pinch. Line, inflate it slightly, put it in an open mold, close the mold, evacuate the gas in the cavity formed by the mold and the parison, and then vacuum pump the device through a small air vent hole to the mold surface Then, high-pressure air is blown into the parison to form the parison into a predetermined shape based on the cavity, and the parison is cooled with a mold to complete the molding. In this way, the molded resin product is opened and taken out. The thing shown in FIG. 7 shows the conventional blow molding machine. 7 shows a so-called side-feed type blow molding machine 1 in which molten resin is supplied from one side of the die head 2, and the high-temperature molten resin pressed by the injection device 4 is the resin supply port 2a. And passes through an annular passage provided between the die head 2 and the mandrel 3 and is discharged from the annular space passage 7 at the lowermost end to form a parison P. A passage 2b and a valve 5 (or plug) provided outside the passage 2b are disposed at a position 180 ° away from the resin supply port 2a of the die head 2. The core 3a is connected to the paricon rod 6a penetrating the mandrel 3 and is slightly moved up and down in the vertical direction by the operation of the paricon cylinder 6 to control the wall thickness of the parison P (gap). ) Can be adjusted.

[0003]

However, in the blow molding machine 1 having such a conventional single-layer structure die, it is not possible to obtain a two-layer hollow molded product at the same time by molding once. Therefore, it is possible to produce a blow-molded product in which a resin sheet (resin film) is interposed between the discharged parison and the mold cavity, the mold is clamped, and the resin sheet is bonded to the surface. Conventionally, it was implemented. However, in this method, it is difficult to obtain a molded product having a smooth surface due to air pockets generated between the parison and the resin sheet, and consideration should be given to providing the resin sheet with fine through holes for deaeration. It is necessary and inevitably causes a cost increase.

On the other hand, there is also a method of obtaining a two-layer hollow molded article by adhering resin or inorganic powder on the surface of the parison. For example, Japanese Patent Laid-Open No. 05-096610 discloses a method of providing a powder adhering device for blowing out powder between a die device and a die device. However, in this method, not only is the device increased in size and equipment costs are increased, but also the parison itself is lengthened and uneconomical,
There is a drawback that the yield becomes poor. Further, in the case of obtaining a three-dimensionally bent irregularly shaped product, the mold cavity shape is also complicatedly bent accordingly, and it is difficult for the suspended parison to smoothly fit in a predetermined mold space. There was also a problem.

[0005]

[Means for Solving the Problems] In the case of forming a molded product having a complicatedly bent shape by solving the above problems, the equipment cost is low, and the powder is easily and easily formed on the parison surface. In order to provide a blow molding method and device for a hollow molded article capable of adhering, in the present invention,
In a first aspect of the present invention, in a blow molding method for a hollow molded article, the parison discharged from an annular resin passage between a die head and a core attached to a lower end of a mandrel is sandwiched by a pair of left and right molds and blow molded, A pair of left and right dies are formed in a shape having a cavity shape that is three-dimensionally bent when the dies are closed, and the space formed between the dies opened to an arbitrary opening amount is set on both side surfaces and the top. While making a closed space that is surrounded by the surface and the bottom surface and is almost closed, while sucking the gas inside the closed space from the lower part and discharging the parison into the cavity in the closed space, On the outer surface of the parison, powder of a resin material or an inorganic material supplied together with gas from the upper end of the die is attached, and after the parison reaches a predetermined length, the discharge drop of the parison is stopped. The mold upper end and the mold lower end, and the mold cavity surface is heated in advance to the softening point temperature of the higher of either the powder resin material or the parison resin material, and then the mold is clamped. After blowing, the molded article was taken out after cooling to a temperature sufficient for taking out the molded article. Further, in the second invention,
In a blow molding device consisting of an injection device and a die device for discharging the molten resin supplied by the injection device from the lower end as a parison and a pair of left and right mold devices for blow molding with the parison sandwiched, a pair of left and right molds, Formed into a shape that has a three-dimensionally bent cavity shape when the mold is closed,
A medium passage for heating or cooling the mold is provided inside the mold, and a pair of front and rear side shutters that can be freely opened and closed in the mold advancing and retracting direction are provided on the outer surface of the mold, and the upper end of the mold and the metal mold are connected. A pair of left and right top shutters that can be freely opened and closed in the mold advancing and retracting directions and a bottom shutter that can be moved up and down are provided at the lower end of the mold to form a closed mold space when the mold is opened. Is provided with a discharge pipe for sucking gas in the closed space and for carrying the powder stored in the powder hopper by air, and for collecting gas containing the discharged powder by suction to collect dust. A dust device was connected to the discharge pipe.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION According to the present invention, in a blow molding method for a hollow molded product, a pair of left and right molds are formed into a shape having a cavity shape which is three-dimensionally bent when the mold is closed, and the mold is arbitrarily opened. While forming a space between the two molds opened in a quantity on both side surfaces, a top surface and a bottom surface to be a closed space which is almost closed, while sucking the gas inside the closed space from the lower part, While discharging the parison and introducing it into the cavity in the closed space, while adhering the powder of the resin material or the inorganic material supplied together with the gas from the upper end of the mold to the outer surface of the parison during the discharging, ,
After the parison reaches a predetermined length, the discharge lowering of the parison is stopped to close the mold upper end and the mold lower end, and the mold cavity surface is preliminarily set to the powder resin material or the parison resin material. After heating above the softening point temperature, whichever is higher, the mold was clamped and blown, and then the molded product was taken out by cooling to a temperature sufficient to take out the molded product. It is pulled by the suction force and smoothly introduced into the complex cavity, and the powder adheres sufficiently to the outer surface of the parison in the high temperature molten state, and then the mold heated to the softening point temperature of the resin or higher. A two-layer hollow molded product that is pressed by blowing and is smoothly and firmly bonded is completed. In the second invention,
When spraying powder, the space surrounded by both molds is almost completely sealed by a side shutter, a top shutter, and a bottom shutter that are both expandable and contractible, and the parison is sucked while sucking the gas in the sealed space from the bottom. Since the parison is smoothly introduced, the powder is also injected into the closed space in the negative pressure state, so that the surrounding work environment is not polluted. Further, since the discharged extra powder is collected by the dust collector, it is economical and a desired powder layer can be automatically formed on the outer surface of the parison as needed.

[0007]

Embodiments of the present invention will be described below in detail with reference to the drawings. 1 to 5 relate to an embodiment of the present invention, FIG. 1 is an overall vertical cross-sectional view of a blow molding device when a mold is opened, FIG. 2 is an overall vertical cross-sectional view of a blow molding device when a mold is closed, and FIG. 1 is a plan view taken along line AA, FIG. 4 is a plan view taken along line BB of FIG. 1, FIG. 5 is a side view taken along line CC of FIG. 3, and FIG. 6 is a mold temperature change of the blow molding method. It is a graph to explain. 1 to 5, the die head 11 of the blow molding apparatus 100
A mold device 20 is provided below the pair of right and left movable platens 22, 22 and a mold 24 attached to each of them.
24 is disposed via the mold clamping cylinder 23 so as to be freely contactable and separable. At the top of the mold 24, a pair of left and right top surface shutters 30 that move forward and backward through the air cylinder 32 in the mold opening / closing direction are disposed, and at the lower end of the mold 24, the air cylinder 52 is also vertically arranged. A bottom shutter 50 that is integrally formed via a bottom and is freely movable is provided. Further, as shown in FIG. 4, a pair of front and rear side shutters 60 that cover the side surface of the mold 24 and move back and forth through the air cylinder 62 in the mold opening / closing direction are provided. In this way, in the mold open state in which the mold is held at an arbitrary mold opening amount that allows the parison P to descend without any hindrance, the space surrounded by both molds has a pair of front and rear side shutters 60, 60 and a pair of left and right side shutters. Top shutter 30, 30
And an integrated bottom shutter 50 form a closed space Q that is isolated from the surroundings.

Below the top shutter 30, the powder stored in the powder tank 40 is pneumatically conveyed by compressed air injected by an air compressor 42 via a supply pipe 44, as shown in FIG. As shown in FIGS. 3 and 5,
Powder supply ducts 3 arranged on both sides of the top shutter 30
It is injected into the mold space through 0a. Powder duct 3
In the inside of 0a, as shown in FIG.
0b is provided so that the powder is evenly dispersed in the closed space Q. On the other hand, the bottom shutter 50 sucks the gas in the closed space Q and collects the remaining powder that has been injected into the closed space Q and not attached to the parison P and a vacuum pump ( (Or a suction fan) 72 is connected to a discharge pipe 70 including a flexible pipe.
Is attached.

A medium passage 24a for heating or cooling the cavity surfaces of the molds 24, 24 is arranged in a portion of the molds 24, 24 facing the cavity surfaces by switching a heat medium or a coolant as needed. It is installed and connected to a medium (heat medium or refrigerant body) switching supply device (not shown).

Further, a split mold 80 is provided between the top shutter 30 and the upper end of the mold 24 so as to be opened and closed by an air cylinder 82 so as to be movable back and forth in the mold opening and closing direction. Similarly, a split mold 90 that is opened and closed by an air cylinder 92 so as to be movable back and forth in the mold opening / closing direction is disposed between the bottom shutter 50 and the lower end of the mold 24. The role of the split molds 80 and 90 is to close the split molds 80 and 90 before clamping and blowing on the parison P after completion of discharge hanging of the parison P and adhesion of powder on the way, as described later. By this, the parison P is matched with the complicatedly curved cavity shape. However, when the upper end and the lower end of the parison P can be sufficiently bonded by closing the mold, the split molds 80 and 90 are used. It can be omitted.

On one of the molds 24, 24, a blow pin 26 used for blowing inside the parison P after the mold is closed is provided so as to pass through the movable platen 22 and the mold 24 so as to be movable back and forth. It

The operation of the blow molding apparatus 100 for hollow articles of the present invention having the above-described structure will be described.
First, the molds 24, 24 are opened, and as shown in FIG. 1, the top shutter 3 is held with the split molds 80, 90 held open.
The shutters 0 and 30 and the bottom shutters 50 and 50 are moved to the closed state, and the side shutters 60 and 60 are also raised to the closed state as shown in FIG. Next, while moving the vacuum pump (or suction fan) 72 to suck the gas in the closed space Q and discharge the parison P from the die device 20, the air compressor 42 is operated to remove the powder in the powder tank 40. Air is conveyed via the supply pipe 44, and the powder supply duct 30a
The powder is further ejected into the closed space Q, and the powder is sequentially attached to the outer surface of the descending parison P. The amount of powder adhered depends on the capacity of the feeder attached to the bottom of the powder tank and the air compressor 42.
Control and adjust the air volume of. When the powder is sprayed while the parison P is descending, it is smoothly introduced into the bent cavity space by being introduced by the suction force of the vacuum pump (or suction fan) 72. The powder that has not adhered is collected and collected by the dust collector 74 via the discharge pipe 70 under the bottom shutter 50. In this way, when the drooping of the parison P ends, the powder injection is stopped, the top shutter 30, the side shutter 60, and the bottom shutter 50 are retracted and retracted, and the split mold 80 and split mold 90 are moved forward. After closing the mold, the mold is closed as shown in FIG. 2, and the parison P is sandwiched between both molds 24, 24 and blown to mold.

The blowing pressure of the blowing after closing the mold completely eliminates the air between the surface of the parison P and the surface of the mold cavity in contact with the parison P, and the air remains between them to form bubbles on the surface of the molded product. In order to prevent such defects, the pressure is at least 4 kgf / cm ² .

The molds 24, 24 are preheated before the molds are closed. The heating temperature and cooling temperature of the mold 24 are the parison P
The proper temperature is selected according to the resin type of the resin material of the powder or the powder to be attached thereto. That is, in order to improve the surface property of the blow-molded product, in other words, in order to improve the surface transferability of the molded product, the parison resin or the powder resin is heated to a temperature higher than the softening point temperature of the higher one, After the transfer is sufficiently performed, it is cooled immediately. When the powder is an inorganic material, the mold 24 is heated to the softening point temperature of the parison resin or higher.

The softening temperature of the resin is equal to the glass transition temperature in the case of the amorphous resin, and 110 ° C. to 1 in the case of the ABS resin.
30 ° C., 120 ° C. to 140 ° C. for modified PPO resin
It is a degree. On the other hand, in the case of a crystalline resin, the temperature between the crystallization temperature and the melting point is suitable, 130 ° C to 160 ° C for PP and 100 ° C to 1 ° C for PE.
The temperature is 30 ° C and 180 ° C to 230 ° C for nylon 6. On the other hand, the cooling temperature is set to about 80 ° C. to 100 ° C., and the temperature change of the mold temperature during one step is, for example, as shown in FIG. 6, two methods of changing the temperature curve A and the temperature curve B. There is, and either may be used. Temperature curve A
Is called the "cool start" method in which the mold temperature is low when the parison P is injected and the mold is closed, and the temperature curve B is called the "hot start" method in which the mold temperature is high when the mold is closed. Various types of oil, water, and pressurized water (steam) can be used as the heat carrier and refrigerant.
Is preferably used, and it is desirable to use the same substance at different temperatures. In addition to the case of heating and cooling the mold 24 as described above, a method of directly heating the surface of the parison P from the outside with a light source or a heat source may be adopted.

According to the method of the present invention, as described above, the powder can be attached to the outer surface of the parison P to easily and easily form a two-layer hollow article. A resin sheet may be attached to the outside of the powder layer. In this case, the resin sheet used for the laminated blow-molded product may be an ordinary commercial product produced by extrusion molding, but one side (blow-molded product surface side) may have a decorative pattern or a decorative pattern. By using, for example, an ABS extruded sheet, which has been printed, various panel-shaped molded articles having high gloss and arbitrary colors and patterns can be obtained. Its applications include air ducts for air conditioning, for example, various air ducts for air supply and ventilation from the air intake to the room, anti-fog for the wind, or defroster nozzles for defrosting, defroster underhood ducts, resonators, for example, engine rooms. Various ducts and resonators for air intake from the inside air intake to the air cleaner,
Ducts after the air cleaner, resonator tubes, hoses, etc. For example, there are fuel tubes, fuel filler housings, radiator tubes, etc.

The powder is not limited to the resin material,
By adopting inorganic materials such as various ceramics and metal powders, it is possible to obtain a product having a wider range with more strength and decorativeness.

According to the method of the present invention, since the mold is heated at the time of closing the mold for blow molding, the parison P and the powdered resin are heated and softened to a semi-molten state, and the surface of the molded product is A smooth surface without steps can be formed.

[0019]

As described above, in the present invention,
In a blow molding method for a hollow molded product, a pair of left and right dies are formed into a shape having a cavity shape that is three-dimensionally bent when the dies are closed, and the dies are opened to an arbitrary opening amount. The formed space is a closed space which is surrounded by both side surfaces, a top surface and a bottom surface and is substantially sealed, and while discharging the gas inside the closed space from the lower part, discharging the parison, the cavity in the closed space. While being introduced into the inside, while adhering the powder of the resin material or the inorganic material supplied together with the gas from the upper end of the die to the outer surface of the parison during discharging, after the parison reaches a predetermined length. The discharge lowering of the parison is stopped, the upper end of the mold and the lower end of the mold are closed, and the mold cavity surface is previously set to the softening point temperature of the higher of the powder resin material and the parison resin material. After heating, the mold is clamped and blown, and then the molded product is taken out by cooling to a temperature sufficient for taking out the molded product. Therefore, when molding a three-dimensionally bent complex molded product, With a single layer blow molding machine, it is possible to easily and easily obtain a two-layer hollow molded product with excellent surface properties and high transfer at the same time, the equipment cost is low, the yield of the parison is good, and the productivity is high. High operation is possible. In addition, by freely selecting the color of the powder, it is possible to easily, easily, and inexpensively produce a multicolor, multi-layer molded product without changing the color with a single-layer blow molding machine. Further, by adopting a resin sheet to which a decorative pattern and a decorative pattern are added, a variety of designs and designs can be enjoyed. In addition, when the powder is sprayed while the parison is descending, the mold space is a closed space,
Moreover, since the internal gas is sucked into a negative pressure state, the parison can be smoothly introduced into the complicated cavity space, and further, the parison can be operated without contaminating the surrounding work environment. Further, in the method of the present invention, since the mold is heated and cooled during molding, the surface of the powder resin in contact with the mold cavity surface is softened and remelted, and there is no step at the boundary between the powder resin and the parison surface. A two-layer hollow blow molded product is obtained.

[Brief description of drawings]

FIG. 1 is an overall vertical sectional view of a blow molding device according to an embodiment of the present invention when a mold is opened.

FIG. 2 is an overall vertical cross-sectional view of a blow molding device according to an embodiment of the present invention when a mold is closed.

FIG. 3 is a plan view taken along the line AA of FIG.

FIG. 4 is a plan view taken along the line BB of FIG.

5 is a side view taken along the line CC of FIG.

FIG. 6 is a graph illustrating a mold temperature change of the blow molding method according to the present invention.

FIG. 7 is an overall vertical sectional view of a conventional blow molding machine.

[Explanation of symbols]

 1 Blow Molding Machine 2 Die Head (Die) 2a Resin Supply Port 3 Mandrel 3a Core 4 Injection Device 5 Valve 6 Paricon Cylinder 6a Paricon Rod 7 Annular Space Passage 8 Die Device 11 Dice Head 12 Pre-pinch 20 Mold Device 22 Movable platen 23 Mold clamping cylinder 24 Mold 24a Medium passage 26 Blow pin 30 Top shutter 30a Powder supply duct 30b Rectifier plate 32 Air cylinder 40 Powder tank 42 Air compressor 44 Supply pipe 50 Bottom shutter 52 Air cylinder 60 Side shutter 62 Air Cylinder 70 Discharge pipe 72 Vacuum pump 74 Dust collector 80 Split mold 82 Air cylinder 90 Split mold 92 Air cylinder 100 Blow molding device P Parison Q Closed space

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Claims (2)

[Claims] 1. A blow molding method for a hollow molded product, wherein a parison discharged from an annular resin passage between a die head and a core attached to the lower end of a mandrel is sandwiched between a pair of left and right molds and blow molded. A pair of molds are formed into a shape having a cavity shape which is three-dimensionally bent when the molds are closed, and the space formed between the molds opened to an arbitrary mold opening amount is defined by both side surfaces and top surface. And a substantially enclosed space enclosed by the bottom surface, while sucking the gas inside the enclosed space from the lower part and discharging the parison into the cavity in the sealed space, The powder of resin material or inorganic material supplied together with gas from the upper end of the die is attached to the outer surface of the parison, and the discharge lowering of the parison is stopped after the parison reaches a predetermined length. And close the upper and lower ends of the mold and heat the mold cavity surface to the softening point temperature of the higher of either the powder resin material or the parison resin material in advance, and then clamp the mold. A blow molding method for a hollow molded product, in which the molded product is taken out by cooling to a temperature sufficient to remove the molded product after blowing. 2. A blow molding device comprising an injection device, a die device for discharging molten resin supplied from the injection device as a parison from the lower end, and a pair of left and right mold devices for blow molding sandwiching the parison. Is formed into a shape having a three-dimensionally curved cavity shape when the mold is closed, a medium passage for heating or cooling the mold is provided inside the mold, and the mold is moved back and forth on the outer surface of the mold. A pair of front and rear side shutters that can be expanded and contracted in any direction are provided, and a pair of left and right top shutters that can be expanded and contracted in the mold advancing and retracting directions and a bottom shutter that can be moved up and down are provided at the upper and lower mold ends Is provided to form a mold space in a closed space when the mold is opened, and a discharge pipe for sucking gas in the closed space just below the bottom surface shutter and carrying the powder stored in the powder hopper by air. Distribute And, and, a hollow molded article blow molding apparatus formed by connecting a dust collector for dust collection sucking gas containing exhaled powder exhaust extraction tube.