JPH0957828A - Lamination blow molding method - Google Patents

Abstract

(57) 【Abstract】 PROBLEM TO BE SOLVED: To provide a bonded molded product which can reduce the amount of a resin sheet used and has excellent surface properties. A laminating blow molding method in which a resin sheet is laminated on the outer surface of a parison ejected from a die and sandwiched by a pair of left and right molds to form a hollow molded article, in which the parison is ejected from the die. Immediately after that, the front end of the resin sheet is pinched together with the front end of the parison by the parison pinch device, the resin sheet is pulled out in synchronization with the parison and hung for a predetermined length, and then sandwiched between the molds to close the mold. At the same time as blowing, the mold is heated until it exceeds the temperature at which the surface of the resin sheet softens, and then cooled to a temperature sufficient to take out the molded product, and then the molded product is taken out.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bonding blow molding method for molding a molded product in which a resin sheet is bonded to the surface of a parison, and in particular, when the parison is pinched, the resin sheet is pinched together and synchronized with the parison. The present invention relates to a bonding blow molding method in which the material is drooped.

[0002]

2. Description of the Related Art FIG. 8 is a sectional view of a conventional blow mold. As shown in FIG. 8, a mold 9 having a cavity for molding a blow molded body, a die head 73 for discharging a synthetic resin parison 80 into the mold 9, and a gas for blowing gas into the parison 80. It has a gas blower 93. Further, a film supply device 2 for supplying the film 1 into the molding die 9 and a rotary winding type residual film drawing device 3 for winding up the residual film which has not been joined to the blow-molded body after the blow molding. Have and.
Further, it has a film cutter (not shown) for cutting the film which is not joined after the molding.

The mold 9 comprises a core mold 91 for molding the bottom surface of the blow molded body 8 and a cavity mold 92 for molding the outer surface of the blow molded body 8 as in the prior art. Hydraulic cylinders 99 and 100 for closing and opening both dies are connected to die support plates 97 and 98 provided at the rear portions of both dies. Further, parison pinches 95a and 95b using spring springs are arranged on the lower facing surfaces of the core mold 91 and the cavity mold 92. In addition, the die head 73
Are located above the mold 9. The die head 73
A molding machine 72 that melts the synthetic resin material 82 and supplies the softened synthetic resin to the die head 73 is connected to the molding machine 72. The die head 73 is a cylindrical parison 80.
It has an air supplier (not shown) for supplying compressed air before blow molding.

The film supply device 2 has a pair of tension rollers 21 and 22, and the surplus film drawing device 3 has a pair of tension rollers 32. The rollers 22 and 32 are located above and below the cavity mold 92. The film 1 is stretched between the supply device 2 and the drawing device 3 via the rollers 21, 22, and 32 while being lightly tensioned. The film 1 includes a cavity mold 92 and a parison 80.
It is arranged to be located between and.

The core mold 91 has a gas blower 9 for injecting air into the parison 80 during blow molding.
3 is provided. Further, the cavity mold 92 is provided with an air vent hole 96, a core passage 101, and an air vent pipe 102, as shown in FIG.

Next, in manufacturing the blow molded body 8, as shown in FIG. 10, the film 1 is arranged as described above with the core mold 91 and the cavity mold 92 opened. Next, the parison 80 of synthetic resin in a softened state is discharged from the die head 73 as in the conventional case. Compressed air is supplied from the die head 73 into the hollow portion 83 of the parison 80.

When the parison 80 is sufficiently discharged, the core mold 91 and the cavity mold 92 are gradually closed by operating the hydraulic cylinders 99 and 100, as shown in FIG. At this time, the parison 80 is first sandwiched between the core mold 91 and the film 1, the parison 80 and the film 1 contact each other, and the air between them is removed. Then, when both molds are further closed, the outermost surface of the film 1 contacts the cavity surface 103 of the cavity mold 92.

The parison 80 is sandwiched between the core mold 91 and the cavity mold 92, and the lower part thereof is gripped by the parison pinches 95a and 95b. Further, the outer peripheral portion of the film 1 is sandwiched between the peripheral portions of the core mold 91 and the cavity mold 92.

Next, as shown in FIGS. 12 and 13, the blowing needle 10 of the gas blowing device 93 is inserted into the hollow portion 83 of the parison 80.
4 is inserted and compressed air is injected into the hollow portion 83.
As a result, the parison 80 is expanded, and the outer peripheral surface thereof is pressed against the mold surface of the core mold 91 and the cavity mold 92 side. The film 1 is pressed against the cavity surface 103. Therefore, the film 1 is integrally bonded to the surface of the parison 80. Also, during this blow molding, on the cavity mold 92 side, the stagnant air between the film 1 and the cavity surface 103 is removed to the outside through the air vent hole 96 and the air passage 101.

Next, after the parison 80 is cooled and solidified in the mold 9, the core mold 91 and the cavity mold 92 are opened. Then, the remaining film 1 not joined to the blow-molded body 8 is cut by a cutter, and the blow-molded body 8 is taken out. Thereby, the blow molded body 8 is obtained. The residual film 1 is wound by rotating the residual film drawing device 3, and a new film 1 is positioned in front of the cavity surface 103 (FIG. 8).

[0011]

However, the above-mentioned conventional bonding blow molding has the following problems. When the operator tries to manually pull the leading end of the film 1 on the residual film pulling device 3 via the tension rollers 21, 22, and 32 to stretch the film 1 after the laminating and forming, the working time is long. As a result, the molding cycle becomes longer.

Since the length of the effective film 1 attached to the surface of the parison 80 is shorter than the length of the film 1 which is stretched between the film supply device 2 and the residual film drawing device 3, A surplus film 1 is likely to be formed every time when laminating is performed.

The parison 80 and the film 1 are placed between the two molds.
When the film 1 is attached to the surface of the parison 80 after the positioning, the deaeration between the parison 80 and the film 1 is likely to be insufficient, and there is a problem that the adhesiveness is deteriorated and the surface property of the molded product is poor.

The present invention has been made in view of the above problems, and it is possible to reduce the amount of the resin sheet used and to obtain a bonded molded product having an excellent surface property without producing an excessive film during molding. A method for laminating blow molding is provided.

[0015]

In order to achieve the above object, in the present invention, a resin sheet is attached to the outer surface of a parison ejected from a die and sandwiched between a pair of left and right dies to form a hollow molded article. A method of laminating and blow molding, in which the parison is pinched with the tip of the resin sheet by a parison pinch device immediately after the parison is injected from the die, and the resin sheet is pulled out in synchronization with the parison. While hanging down for a predetermined length, it is sandwiched between molds, the molds are closed, and at the same time, the molds are heated until the temperature exceeds the temperature at which the surface of the resin sheet softens, and then the molded product is taken out. After cooling to a sufficient temperature, the molded product was taken out.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, after the tip of the parison discharged from the die and the tip of the resin sheet are held at substantially the same position, the parison and the resin film are simultaneously pinched by a pre-pinch, and the subsequent process is continued. When the parison is drooped, the resin sheet is rewound so as to be pulled by the parison. Since the parison is successively adhered along the surface of the parison that has drooped to a predetermined length, degassing between the parison and the resin sheet can be performed along with the hanging of the parison, and a surplus resin sheet is unlikely to be generated at each laminating molding.

[0017]

Embodiments of the present invention will be described below in detail with reference to the drawings. 1 to 7 relate to an embodiment of the present invention, FIG. 1 is an overall longitudinal sectional view of a blow molding machine, FIGS. 2 to 6 are explanatory views showing a molding procedure of a bonded molded product, and FIG. 7 is a mold. The graph which illustrates a temperature change is shown.

In FIG. 1, a pair of left and right molds 7, 7 are disposed below the die head 19 of the blow molding machine 50 so as to be freely contactable with and separated from each other. The feed roll 20 of the resin sheet S is disposed via a roll table (not shown) at a position where it is pinched with the resin sheet S at the front end of the parison P that is discharged and drooped, and is easily synchronized and drooped. The cutter 3 mounted on a mounting base (not shown) inside the feed roll 20 (on the parison P side)
0 is provided.

The cutter 30 is a pair of cutters 30a, 3a.
0b, the tip ends of the cutters 30a and 30b are formed of sharp blades and are arranged so as to face the resin sheet S.
The a and 30b can be brought into and out of contact with each other.

A guide plate 18 is arranged substantially horizontally below the feed roll 20 and the resin sheet supply device 15, and the tip end portion of the resin sheet S is bent inward (toward the mold 7) so that the resin sheet S can easily follow the parison P. Has been.

Reference numeral 16 is a pinch device for simultaneously pinching the parison P and the tip of the resin sheet S.

On the other hand, in the portion of the mold 7 facing the cavity surface, a heating medium or a cooling medium is switched and flowed if necessary,
Medium passage 7 for heating or cooling the cavity surface of the mold 7.
a (not shown) in which a is disposed (heat medium or refrigerant body)
It is connected to the switching supply device. Further, a plurality of vent holes 7b, which penetrate the die 7 from the cavity surface of the die 7 at right angles to the cavity surface and discharge air, are arranged at appropriate intervals. Further, in order to positively suck the air exhausted from the vent holes 7b, the collecting duct 10 is provided so as to cover the outside of the mold 7, and the exhaust pipe including the electromagnetic valve 12 and the suction fan 14 is provided. 11 is provided. Alternatively, the mold 7 may use a metal innumerable fine vent holes, that is, a porous metal, instead of the vent hole 7b.

The resin sheet S wound around the resin sheet supply device 15 may be the same type of resin as the parison P, or may be a different type from the parison P. Resin sheet S
May be a multilayer resin sheet, a metal foil, paper, glass fiber or the like may be laminated between the sheets in a sandwich form, or the sheet may be filled with an inorganic substance (glass fiber, inorganic mineral, etc.). However, since the sheet material attached to the burr portion may be crushed and reused for the next molding shot, basically the same material as the parison P is desirable.

The thickness of the resin sheet S is not preferably too thick in order to manufacture a laminated blow-molded product, and is usually 1 mm or less, but preferably 0.5 mm or less. If the resin sheet S is too thick, it is difficult to obtain a molded product that matches the cavity shape in the deep shape in which wrinkles easily occur. In addition, the cooling time after molding becomes long and the productivity is lowered. Further, if it is too thin, the resin sheet S may be damaged during molding. Resin sheet S
The surface of the parison P is not
And the resin sheet S are provided with a plurality of fine through holes for exhausting air, which are arranged in a lattice or zigzag pattern.

The diameter of the fine through holes is 0.1 mm to 1 mm.
It is preferable that the arrangement density is 0.1 mm or more and 0.3 mm or less, and the arrangement density is at least 1 per 100 cm ^2, but preferably 4 or more per 100 cm ^2.
It is desirable that the number is 00 or less.

The blowing pressure of the blowing after the mold is closed completely eliminates the air between the surface of the parison P and the resin sheet S attached to the parison P, and the air remains between the two to leave the surface of the molded product. To prevent defects such as bubble formation,
The pressure is at least 4 kgf / cm ² . Reference numeral 24 is a blow pin for blowing into the parison P for blowing.

The heating temperature and the cooling temperature of the mold 7 are properly selected according to the kind of resin on the surface of the resin sheet S which is in contact with the mold. That is, the resin sheet S is usually manufactured by extrusion molding and has a poor surface property. In order to improve the surface property of the bonded blow-molded product in the present invention, in other words, the surface transferability of the molded product is improved. Therefore, the resin is heated to a temperature at which the resin softens or higher, and after the surface transfer is sufficiently performed, the resin is quickly cooled. In addition, in order for the parison resin to appear on the surface of the molded product, it is necessary to heat the parison resin to a temperature at which the parison resin softens.

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 changed to a temperature curve A and a temperature curve B as shown in FIG. There are various methods and any method may be used.
The 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 kinds of oil, water, and pressurized water (steam) are used as the heat medium and the coolant, and it is desirable to use the same substance having different temperatures. In addition to the case where the mold 7 is heated and cooled 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.

On the surface of the resin sheet S on the parison contact side,
Allow the adhesive to be applied beforehand, or spray-apply an adhesive solution in the form of a spray, or
It is desirable to consider brushing so as to facilitate the bonding with the surface of the parison P during molding.

The blow molding machine 50 configured as described above.
The operation of the blow molding method of the present invention will be described.

First, an appropriate amount of parison P is ejected from the die head 19 while holding both molds 7 and 7 in the mold open state (a preferable hanging position of the parison P tip is located slightly below the pinch device 16). It is preferable that the feed roll 2 is provided so that the front end of the resin sheet S follows the guide plate 18.
0 (20a, 20b) is rotated in the direction of the arrow so that the lower portions of both ends of the parison P and the resin sheet S are substantially at the same position (FIG. 2). During this time, the temperature of the molds 7, 7 is started to rise according to one of the temperature curves A, B shown in FIG.

Next, the pinch device 16 is moved closer to the parison P and the resin sheet S are simultaneously pinched, and at the same time, the upper feed roll 20a is moved in the direction of the arrow (FIG. 3).

When the parison P and the lower portion of the resin sheet S are simultaneously pinched, the pinch device 16 is opened, and the molten resin is continuously pressed into the die head 19 from the injection device (not shown) so that the parison P and the resin sheet S are synchronized. On the other hand, while hanging down, the resin sheet S is brought into intimate contact with the parison P from below to above. Therefore, the residual air present between the parison P and the resin sheet S is completely eliminated in accordance with the close contact between the parison P and the resin sheet S (FIG. 4).

After the resin sheet S is hung synchronously with the parison P to a predetermined position, and the parison P and the resin sheet S are interposed between the two molds 7 and the mold is closed and sandwiched, the resin sheet is placed on the surface of the parison P. It is molded in a state where S is attached (FIG. 5). On the cavity surfaces of the molds 7 and 7, the temperature is in the vicinity of the softening point of the resin sheet S, the surface of the resin sheet S is softened and melted, and the mold cavity surface is pressed and the mold cavity surface is transferred. The surface of the parison and the surface of the resin are pressure-bonded together and bonded by the pressurized air blown into the parison P via the blow pin.

After that, the upper end of the resin sheet S is attached to both cutters 30.
When a and 30b are pressed from both sides, the resin sheet S is cut. By the heat / cool start shown in FIG. 7, the resin sheet S firmly adheres to the parison P and is cooled, and after opening both the molds 7, it is re-pinched by the pinch device 16 and taken out as a bonded molded product 26 (Fig. 6).

[0037]

As is apparent from the above description, in the present invention, a resin sheet is attached to the outer surface of the parison ejected from the die and sandwiched by a pair of left and right molds to form a hollow molded product. A bonding blow molding method, in which the parison pinch device is used to pinch the tip of the resin sheet together with the parison tip immediately after the parison is ejected from the die, and the resin sheet is pulled out in synchronization with the parison. After hanging down for a predetermined length, it is sandwiched between molds, the molds are closed, and at the same time the molds are heated until the surface of the resin sheet is softened, and then the molds are removed. By removing the molded product after cooling to a proper temperature, the work time for positioning the tip of the resin sheet before bonding is unnecessary. The molding cycle can be shortened. Since the resin sheet is preheated by the heat from the parison while the resin sheet simultaneously hangs down with the parison, the adhesion between the parison and the resin sheet is improved. Due to the synchronous hanging of the parison and the resin sheet, the resin sheet is brought into intimate contact with the parison in order from below, so that residual air between the parison and the resin sheet is eliminated and the adhesion is improved. Since the front end of the resin sheet is pinched at the same time as the front end of the parison, the surplus resin sheet is less likely to come out and the resin sheet can be reduced.

[Brief description of drawings]

FIG. 1 is an overall vertical sectional view of a blow molding machine.

FIG. 2 is an explanatory diagram showing an operation procedure of bonding according to the present invention.

FIG. 3 is an explanatory diagram showing a continuation of the operation shown in FIG.

FIG. 4 is an explanatory diagram showing a continuation of the operation shown in FIG.

FIG. 5 is an explanatory diagram showing a continuation of the operation shown in FIG.

FIG. 6 is an explanatory diagram showing a continuation of the operation shown in FIG.

FIG. 7 is a graph illustrating changes in mold temperature.

FIG. 8 is a sectional view of a conventional blow mold.

FIG. 9 is a cross-sectional view of a conventional mold during blow molding.

FIG. 10 is a cross-sectional view taken along the line BB of FIG.

FIG. 11 is a transverse cross-sectional view during blow molding.

FIG. 12 is a vertical sectional view at the end of blow molding.

FIG. 13 is a cross-sectional view of a bonded molded product.

[Explanation of symbols]

 4 Suction Fan 7 Mold 7a Medium Passage 7b Vent Hole 10 Collecting Duct 11 Exhaust Pipe 12 Solenoid Valve 14 Suction Fan 15 Resin Sheet Supply Device 16 Pinch Device 18 Guide Plate 19 Dice Head 20 Feed Roll 20a Top Feed Roll 20b Bottom Feed Roll 24 Blow pin 26 Laminated product 30 (30a, 30b) Cutter 50 Blow molding machine P Parison S Resin sheet

Claims (1)

[Claims] 1. A laminating blow molding method in which a resin sheet is laminated on the outer surface of a parison ejected from a die and sandwiched by a pair of left and right molds to form a hollow molded article, wherein the parison is ejected from the die. Immediately after being squeezed, the tip of the resin sheet is pinched together with the tip of the parison by the parison pinch device, and the resin sheet is pulled out for a predetermined length in synchronization with the parison and then sandwiched between the dies to form a die. At the same time as closing and blowing, the mold is heated until the temperature exceeds the temperature at which the surface of the resin sheet softens, and then the molded product is taken out after cooling to a temperature sufficient for taking out the molded product. Laminating blow molding method.