JPH0970878A - Method and apparatus for blow molding of hollow molded product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable two-layered hollow molding excellent in surface properties by one molding by supplying a resin powder to the outer surface of a parison on the way of emission along with gas from the upper end part of a mold to bond the same to the outer surface of the parison and preheating the cavity surface of the mold to its softening temp. SOLUTION: Molds 22, 24 are opened and the shutters 30, 50 of top, bottom and side surfaces are opened and the temp. of the molds 24, 24 are preliminarily raised to a temp. equal to or higher than the softening point of a supplied resin. Next, an air compressor 42 is operated while a parison P is emitted from a die device 10 and the powder in a powder tank 40 is fed by air through a supply pipe 44 to be injected into a space Q from nozzles 46a, 46b to be successively bonded to the outer surface of the falling parison P. When the emission and suspension of the parison P is completed, the injection of the power is stopped and the respective shutters are respectively allowed to retreat and the closed parison P is held between both molds 24, 24 to be subjected to blow molding and the molds are cooled to take out a molded product. By this constitution, two-layered hollow molding can be facilitated.

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 apparatus for molding a hollow molded product in which powder is adhered to the surface of a parison, and more particularly to a blow molding machine for a single layer, in which the parison surface is formed. TECHNICAL FIELD The present invention relates to a blow molding method and device for a hollow molded product, which allows powder of a resin material or an inorganic material of the same or different kind as a parison to be easily and easily attached.

[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, with this method, it is difficult to obtain a molded product having a smooth surface due to air pockets 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 that blows 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.

[0005]

[Means for Solving the Problems] A blow molding method and apparatus for a hollow molding product, which solves the above problems and is capable of easily and easily adhering powder to the surface of a parison at low equipment cost. Therefore, in the first aspect of the present invention, the parison discharged from the annular resin passage between the die head and the core attached to the lower end of the mandrel is sandwiched between the pair of left and right molds and blow molded. In a blow molding method for a hollow molded product, a powder of a resin material supplied together with a gas from the upper end of a mold is attached to the outer surface of a parison during discharge, and the mold cavity surface is previously formed by the powder resin material. Alternatively, the parison resin material is heated to a temperature higher than the softening point temperature, whichever is higher, and then cooled to a temperature sufficient to remove the molded product after performing mold clamping and blowing. It was decided to take out a molded article Te. Further, in the second invention, in the first invention, the powder is ceramic or metal, and the heating temperature of the mold is not less than the softening point temperature of the parison resin material. Further, according to a third aspect of the present invention, there is provided a blow molding device comprising an injection device, a die device for ejecting a molten resin supplied by the injection device as a parison from a lower end, and a pair of left and right mold devices for blow molding with the parison sandwiched therebetween. , A pair of front and rear side shutters that can be expanded / contracted in the mold advancing / retracting direction are provided on the outer surface of the mold, and left and right can be expanded / contracting in the mold advancing / retracting direction at the mold lower end and the mold upper end, respectively. A pair of bottom shutter and top shutter are provided, and a discharge nozzle of a powder supply pipe that conveys the powder stored in the powder hopper by air is provided directly below the top shutter, and the discharged powder is A dust collecting device for collecting the body is connected to the bottom shutter.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, in a blow molding method for a hollow molded article, a powder of a resin material supplied together with gas from the upper end of a mold is attached to the outer surface of a parison during discharge, Sufficient to remove the molded product after heating the mold cavity surface above the softening temperature of the powder resin material or the parison resin material, whichever is higher, and then performing mold clamping and blowing. Since the molded product was taken out by cooling to a temperature, when the powder was a resin material, the powder once changed from a solid state to a molten liquid state and completely adhered to the outer surface of the parison, which was also in the molten state, and had a smooth surface. A two-layer hollow molded product that is firmly bonded with is completed. In the second invention, ceramics, metal powders and the like can be adopted without limiting the powder to the resin material, so that various molded products can be obtained and the product area is expanded. In the third invention, when the powder is sprayed, the space surrounded by both molds is almost completely sealed by the side shutter, the top shutter, and the bottom shutter which are both expandable and contractible, and the surrounding work environment is polluted. It is economical because it does not exist and the excess powder released is collected by the dust collector.

[0007]

Embodiments of the present invention will be described below in detail with reference to the drawings. 1 to 6 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 and 2, the die head 11 of the blow molding device 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. 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 on the top of the mold 24, and the lower end of the mold 24 also moves in the mold opening / closing direction. A pair of left and right bottom surface shutters 50 that move forward and backward via an air cylinder 52 are 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. Thus, when the mold is in the mold open state, the space Q surrounded by both molds has a pair of front and rear side shutters 60, 60 and a pair of left and right top shutters 30, 30.
Similarly, a pair of left and right bottom shutters 50 and 50 are hermetically sealed and 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 FIG. 5, the nozzle 46 at the tip (first nozzle 46a, second nozzle 46b) is injected into the mold space. On the other hand, in each of the bottom surface shutters 50, a discharge pipe 70 formed of a flexible pipe connected to a dust collector (not shown) for collecting the remaining powder that has been injected into the space Q and not attached to the parison P. It 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).

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 shutters 30, 30 and the bottom shutters 50, 50 are moved to a closed state, and the side shutters 60, 60 are also shown in FIG. As shown, move forward and close. Next, while discharging the parison P from the die device 10, the air compressor 42 is operated to supply the powder in the powder tank 40 with the supply pipe 44.
The air is conveyed through the nozzles and ejected into the space Q from the first nozzle 46a and the second nozzle 46b, and the powder is sequentially attached to the outer surface of the descending parison P. The amount of powder adhered is
The volume of the feeder attached to the lower part of the powder tank and the air volume of the air compressor 42 are controlled and adjusted. In this way, when the drooping of the parison P ends, the powder injection is stopped,
Top shutter 30, side shutter 60, bottom shutter 5
0 is retracted and retracted, 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 the mold is opened and closed completely eliminates the air between the surface of the parison P and the surface of the mold cavity which is in contact with the parison P, and the air remains between them to form bubbles on the surface of the molded product. The pressure is at least 4 kgf / cm ² in order to prevent the above defects.

The molds 24, 24 are preheated before the molds are closed. Appropriate temperatures are selected for the heating temperature and the cooling temperature of the mold 8 depending on the resin type of the parison P and the resin material of the powder adhered 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.

The softening temperature of the resin is equal to the glass transition temperature in the case of the amorphous resin, and 110 ° C. to 13 in the case of the ABS resin.
It is 0 degreeC, and is 120 degreeC-140 degreeC about modified PPO resin. On the other hand, in the case of the crystalline resin, the temperature between the crystallization temperature and the melting point is suitable, and in the case of PP, 130 ° C to 160 ° C, and in the case of PE, 100 ° C to 13 ° C.
The temperature is 0 ° 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.

In the method of the present invention, as described above, the powder resin can be attached to the outer surface of the parison P to easily and easily form a two-layer hollow product, but since the decorating property is increased,
Further, a resin sheet can be attached to the outside of the attached 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 daily necessities (chairs, TV stands, bookshelves, cabinets, system kitchens, blackboards, sheds, desk tops, piling tops, furniture doors, side panels, bathtubs, mirror stands, etc.) Home appliances (refrigerator doors, dishwashers) Doors, washing machine doors, washing machine side plates, TVs, speaker boxes, computer housings, etc. Automotive products (spoilers, glove box doors, instrument panels, rear pashal shuffles, door trims, side garnishes, console boxes, road floors, bumpers, fenders) There are trunk lids, motorcycle fenders, outer panels, etc.) Building materials (doors, wall materials, partition boards, partitions, etc.) Daily miscellaneous goods.

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.

Also, by embedding a metal foil or the like on the inner surface of the parison side of the resin sheet, by connecting an electric wire to a floor panel or metal foil capable of heating, a spoiler with a built-in antenna, a glove box door, interior parts, etc. Applications of parts will also be expanded. Further, by combining known techniques such as insert and foam molding, the usage can be further expanded.

According to the method of the present invention, since the mold is heated when the mold for blow molding is closed, 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.

[0018]

As described above, in the present invention,
In a blow molding method for a hollow molded product, a powder of a resin material supplied together with a gas from the upper end of a mold is attached to the outer surface of a parison during discharge, and the mold cavity surface is previously formed by the powder resin material. Alternatively, the parison resin material is heated to a temperature higher than the softening point temperature, whichever is higher, and then molded and blown, and then cooled to a temperature sufficient for the molded product to be taken out, and the molded product is taken out. As a result, a single layer blow molding machine can be used to perform a single molding at the same time to easily obtain a two-layer hollow molded product with excellent surface properties and high transfer, and the equipment cost is low and the parison yield is good. Highly productive 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. 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 in the blow molding method.

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

[Explanation of symbols]

 1 Blow Molding Machine 2 Dice 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 20 Die Device 20 Movable Platen 23 Mold Cylinder 24 Mold 24a Medium Passage 30 Top Shutter 32 Air Cylinder 40 Powder Tank 42 Air Compressor 44 Supply Pipe 46 Nozzle 46a First Nozzle 46b Second Nozzle 50 Bottom Shutter 52 Air Cylinder 60 Side Shutter 62 Air Cylinder 70 Discharge pipe 100 Blow molding device P Parison Q Space

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Claims (3)

[Claims] 1. A blow molding method for a hollow molded product, comprising: parison discharged from an annular resin passage between a die head and a core attached to a lower end of a mandrel is sandwiched between a pair of left and right molds and blow molded. The powder of the resin material supplied together with the gas from the upper end of the mold is attached to the outer surface of the parison in the middle, and the mold cavity surface is preliminarily selected from the powder resin material and the parison resin material. A blow molding method for a hollow molded product, in which a molded product is taken out after being heated to a temperature higher than the higher softening point temperature, then clamped and blown, and then cooled to a temperature sufficient for taking out the molded product. 2. The blow molding method for a hollow molded article according to claim 1, wherein the powder is ceramic or metal, and the heating temperature of the mold is not lower than the softening point temperature of the parison resin material. 3. A blow molding device comprising an injection device, a die device for ejecting a 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, wherein a mold is provided. A pair of front and rear side shutters that can be expanded and contracted in the mold advancing and retracting direction are provided on the outer side of the mold, and a pair of left and right bottom surfaces that can be expanded and contracted in the mold advancing and retracting direction are provided at the mold lower end and mold upper end, respectively. A shutter and a top surface shutter are provided, a discharge nozzle of a powder supply pipe for pneumatically conveying the powder stored in the powder hopper is provided immediately below the top surface shutter, and the discharged powder is collected. A blow molding device for a hollow molded product, in which a dust collecting device for collecting dust is connected to the bottom shutter.