JPH1110719A - Lamination blow molding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bonding blow molding method capable of preforming a resin sheet by the same blow molding machine in advance and blow molding a molded article excellent in surface transferability with high efficiency. . SOLUTION: A resin sheet is sandwiched between a pair of left and right molds outside a parison discharged from an annular resin passage between a die head and a core attached to a lower end of a mandrel and integrated to form a hollow product. A blow-molding method, in which a mold is closed with a resin sheet hanging down between the opened molds, and the mold is heated to a softening temperature of the resin sheet while air is blown into a mold cavity through a blow pin. Perform the work of the preform step of blowing the resin sheet, open the mold until the temperature of the resin sheet reaches the softening temperature,
While the resin sheet is fixed to the molding surface of the mold, the parison is discharged and drooped, and the mold is cooled down to a temperature at which a molded product can be taken out while the mold is closed and blown, and then the mold is opened. Then, the molded product was taken out.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lamination blow molding method for producing a lamination molded product in which a resin sheet is laminated on one or both sides of a parison, and in particular, the surface property of the laminated resin sheet is improved. The present invention relates to a lamination blow molding method for obtaining a lamination molded product.

[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.

FIG. 5 shows a conventional blow molding machine. In FIG. 5, the molten resin is placed on the side 1 of the die head 2.
Shown is a so-called side-feed type blow molding machine 1 supplied from a location, in which a resin in a high-temperature molten state pressed by an injection device 4 is provided between a die head 2 and a mandrel 3 via a resin supply port 2a. Through the open circular passage,
The parison P is formed by being discharged from the lowermost annular space passage 7. A passage 2b and a valve 5 provided outside the passage 2b are provided at a position 180 ° away from the resin supply port 2a of the die head 2.
(Or plug) is provided. The core 3a is connected to a paricon rod 6a penetrating the mandrel 3, and is slightly advanced and retracted in the vertical direction by the operation of the paricon cylinder 6, and a gap (gap) in the annular space passage 7 is used to control the thickness of the parison P. ) Can be adjusted.

On the other hand, a resin sheet is interposed between a parison discharged by using such a blow molding machine 1 and a mold cavity, the mold is clamped, and the resin sheet is bonded to the surface. Conventionally, producing blow molded articles has been practiced.

[0005]

However, in such a conventional lamination blow molding method, the surface properties of the molded article depend on the surface properties of the resin sheet to be laminated, and the extrusion method often used as a resin sheet is used. Molded sheets generally have poor surface properties. In addition, when the surface shape of the molded product is complicated and irregular, the resin sheet may be broken without being stretched, or a defect such as wrinkling may occur. It is necessary to perform preforming along the surface shape of the molded product.
The preform needs to be performed using another mold before performing the lamination blow molding, and accordingly, the number of steps increases and the production cost increases. An object of the present invention is to solve the above-described problems and to perform a preform and a lamination blow molding with the same mold to obtain a lamination blow molding having a good surface property.

[0006]

In order to solve the above-mentioned problems, according to the present invention, in the first invention, a discharge is performed from an annular resin passage between a die head and a core attached to a lower end of a mandrel. This is a lamination blow molding method in which a resin sheet is sandwiched between a pair of left and right dies to form a hollow product outside the parison, and the resin sheet is suspended between the opened dies. Then, while the mold is heated to the softening temperature of the resin sheet, an operation of preforming a resin sheet in which air is blown into the mold cavity through a blow pin is performed, and the temperature of the resin sheet reaches the softening temperature. By opening the mold, the parison is discharged while the resin sheet is fixed to the molding surface of the mold, and the mold is closed, and the mold is closed and blown to a temperature at which a molded product can be removed. After cooling, it was taken out of the molded article mold opening.

In the second invention, the air injected into the mold cavity in the preform step in the first invention is heated in advance to a temperature of 50 ° C. to 100 ° C.

Further, in the third invention, the air to be injected into the mold cavity in the preform process is injected from one of a plurality of blow pins and discharged from any of the other blow pins. did.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a resin sheet is sandwiched between a pair of left and right molds outside a parison discharged from an annular resin passage between a die head and a core attached to a lower end of a mandrel. Is a method of laminating and blow forming a hollow product, wherein the mold is closed while the resin sheet is hung between the opened molds, and the mold is heated to the softening temperature of the resin sheet. Perform the work of the preform process of the resin sheet in which air is blown into the cavity through the blow pin, open the mold until the temperature of the resin sheet reaches the softening temperature, and fix the resin sheet to the mold forming surface. In this state, the parison is discharged and drooped, the mold is closed and blown while the mold is cooled to a temperature at which the molded product can be removed, and then the molded product is opened and the molded product is removed. The resin sheet is deformed in the preform process until it conforms to the mold surface shape, and then the mold is closed and blown together with the parison, so the laminated molded product after blow molding is a resin sheet and core resin parison. A bonded blow-molded product that is fused and integrated and has good surface properties can be obtained.

[0010] In the second invention, the air injected into the mold cavity in the preform step is preliminarily heated from 50 ° C to 100 ° C.
Since the resin sheet is heated to a temperature of up to ° C., the resin sheet is easily softened, and the resin sheet can be surely fitted to the molding surface of the mold.

In the third aspect, the air to be injected into the mold cavity in the preform step is injected from one of the plurality of blow pins and discharged from any of the other blow pins. Since high-temperature and high-pressure air is circulated in a flowing state without being retained in the mold cavity, the efficiency of heat transfer to the resin sheet during the preform process is improved, and uniform and rapid heating is performed.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings. 1 to 4 relate to an embodiment of the present invention. FIG. 1 is an overall vertical sectional view of a blow molding machine, FIG. 2 is a perspective view of the blow molding machine, and FIG. FIG. 4 and FIG. 4 are graphs for explaining the mold temperature change in each step of the lamination blow molding.

1 and 2, a pair of left and right dies 8, 8 are provided below and below a die head 2 of a blow molding machine 1 so as to be freely separated from each other. A roll 20 is formed by winding a resin sheet S formed of a flat plate at a position where it hangs down along the surface of the parison P ejected from the head 2 and hangs down and having a plurality of deaeration holes h formed on the surface. It is arranged via a table 22. Roll 2
The cutter 30 is attached to the roll base 22 at the lower end of the cutter 30. The cutter 30 is formed by a sharp blade with a sharp tip which moves horizontally in the parison direction by the operation of the air cylinder 30a. A cutter receiving seat 30b having a groove into which the cutting edge of 30 is fitted is provided, and the resin sheet S which is hung down can be cut at any time without damaging the surface of the parison P. Further, a sheet clip 24 for holding the lower end of the resin sheet S and holding the resin sheet S in a vertically extended state during operation is provided at the lower end of the mold 8.

On the other hand, a heat medium or a cooling medium is switched and flowed to a portion facing the cavity surface of the mold 8 as necessary.
A medium passage 8a for heating or cooling the cavity surfaces of the molds 8, 8 is provided, and is connected to a medium (heat medium or refrigerant) switching supply device (not shown). Further, a plurality of vent holes (deaeration holes) 8b that penetrate the mold 8 from the cavity surface of the mold 8 at right angles to the cavity surface and discharge air are provided at appropriate intervals. Further, in order to positively suck the air exhausted from these vent holes 8b, the collecting duct 10 is formed so as to cover the outside of the die 8.
Is provided, and an exhaust pipe 11 provided with a solenoid valve 12 and a suction fan 14 is provided. Alternatively, the mold 8 may be made of a metal provided with countless fine air holes, that is, a porous metal, instead of the vent hole 8b. Further, among the dies 8, 8, the dies 8 on the side not provided with the roll 20 of the resin sheet S (the dies 8 on the left side in FIG. At least two or more air inlets 8c and air outlets 8d are provided in the mold 8 in the vertical direction so as to be blown to the back of the seat. A pressure fan 16 is connected to the air inlet 8c via a solenoid valve 12, and a solenoid valve 1 is connected to the air outlet 8d.
2, the suction fan 18 is connected.

The resin sheet S extended up and down with slight tension by the roll 20 and the sheet clip 24 is a sheet made of a smooth resin material formed by extrusion molding. Alternatively, a woven fabric formed by weaving heat-resistant fibers that do not burn even under high heat, or a nonwoven woven sheet made by simply tangling the fibers may be used. In this case, the material of the woven fabric sheet S is a woven fabric obtained by weaving heat-resistant resin fibers such as glass fiber, carbon fiber, polyimide resin, nylon resin, and fluorine resin, and fibers such as polyethylene, polyester, and nylon. An entangled nonwoven fabric is used.

The thickness of the resin sheet S is 0.1 to 1 mm, and it is desirable that a plurality of deaeration holes h having a diameter of 1 mm or less are uniformly arranged on the resin sheet S at a pitch of about 10 mm. A plurality of deaeration ports h formed by punching through the resin sheet S are punched out, the return of the deaeration port h is left as it is without being removed, and the surface with the return of the deaeration port h faces the mold cavity surface. The resin sheet S is heated to a temperature equal to or higher than the softening temperature of the resin sheet S by the high heat received from the mold 8 during the blow molding.
Disappears, thereby preventing adverse effects on the appearance of the molded article.

The mold in the preforming step of the resin sheet S is heated to a temperature higher than the softening point of the material of the resin sheet S. The “softening point” is determined with reference to a temperature represented by a Vicat softening temperature, a heat distortion temperature, and the like. Generally, a glass transition point is used for an amorphous resin, and a surface property of a resin sheet S is used for a crystalline resin. It is necessary to heat the mold to the melting point in order to improve the melting point. For example, 100 to 14 for ABS resin
0 ° C, and 130 to 170 ° C for PP resin.

FIG. 3 shows an operation procedure of the lamination blow molding method. The operation procedure of the lamination blow molding will be described with reference to FIG. 3. In FIG. The resin sheet S is hung down from the roll 20 so as to face the mold cavity surface of the fixed mold 8 and is softly fixed.

Next, the preform forming step of the resin sheet S is started, the molds 8 and 8 are softly closed, and the suction fan 14 is operated to move the resin through the vent hole 8b as shown in FIG. The resin sheet S is drawn into the mold (fixed mold) by sucking air from the surface of the sheet S and the mold (fixed mold) and blowing high-temperature and high-pressure air from the air injection port 8c of the mold (movable mold) 8. (8) Preform into a shape along the mold forming surface of 8.
As described above, the resin sheet S is softly fixed and the mold is closed softly so that the resin sheet S can be moved and changed from the state shown in FIG. 3A to the state shown in FIG. 3B.

In the preform process, the surface of the resin sheet S where the degassing holes h are turned is directed to the mold surface (fixed mold surface) against which the resin sheet S is pressed and fixed, as described above. Air is sucked from the vent hole 8b provided in the resin sheet 8 to help the resin sheet S to follow the mold forming surface. At the same time,
A high-temperature and high-pressure air supplied from a mold (movable mold) 8 on the opposite side is blown onto the back surface of the resin sheet S, and a preform is performed in synchronization with the softening of the resin sheet S due to a rise in mold temperature. If the high-temperature and high-pressure air is heated to 50 ° C. to 100 ° C., the resin sheet S is easily softened, and the cycle is shortened. The lower limit temperature of 50 ° C. of the high-temperature and high-pressure air is a limit below which the softening of the resin sheet S deteriorates and the effect is lost, and if the air temperature is raised more than 100 ° C., the resin sheet S deteriorates. There is fear. The resin sheet S is heated by the high-temperature and high-pressure air and is stretched along the molding surface (mold cavity surface) of the fixed mold 8 while the softening is gradually progressing, so that the resin sheet S reaches the softening temperature. Complete the pro-forming process before.

When the resin sheet preform process of FIG. 3B is completed, the mold is opened and the resin sheet S is fixed to the fixed die 8 as shown in FIG. The parison P is discharged from the first die head 2 and hangs down.

Next, the mold is closed, a blow pin is inserted into the parison P, and blowing is performed.
8 is heated to a predetermined temperature, and air is sucked from the vent hole 8b to suck air interposed between the parison and the resin sheet and between the resin sheet and the mold forming surface, thereby fusing the resin sheet S and the parison P. The integrated blow molding is performed (FIG. 3D).

At this time, if the preform process is too long, the mold temperature becomes too high and the temperature of the resin sheet S becomes too high, the degassing holes h of the resin sheet S are melted and closed, and the intended purpose of the degassing holes h is The air is not completely removed between the parison and the resin sheet, and air is interposed between the two to cause poor adhesion and poor appearance. Conversely, if the preform process is too short and the preform is insufficient, the sheet may be broken, and it is necessary to determine the end time of the preform process properly while monitoring the mold temperature. is there.

Thereafter, the dies 8, 8 are cooled and opened, and the molded product is taken out as a product. FIG. 3E shows a laminated blow-molded product formed in this manner.

FIG. 4 is a graph for explaining a mold temperature change in each step of the lamination blow molding. The mold temperature T is changed in a time-series manner in a sine wave shape with the softening temperature of the resin sheet S as a boundary. . That is, the mold temperature T starting from the time of sheet setting (point t ₁ ) starts the mold heating in the middle of the preform process (point t ₂ ), and the temperature of the mold gradually rises to the softening temperature T _n . Immediately before reaching (point t ₃ ), the preform process is completed, the blow molding process is started, and the mold temperature T
Further rises, and after a certain period of time (point t ₄ ), the cooling process is started and lowered.

The blow pressure of the blow after the mold is closed completely eliminates air between the surface of the parison P and the woven fabric sheet S which is in close contact with and integrated with the parison P, and the air remains between the two to form. to prevent transfer defects caused by such generation of bubbles on the goods surface, at least a 0.1 kgf / cm ^2, and 10 kgf / cm ² or less at maximum. The reason is as follows. The blow pressure is set to 0.1 kgf / cm ²
In the following case, the molding pressure is too small to cause molding failure (the mold cavity shape is not transferred to the parison P). When the blow pressure becomes 10 kgf / cm ² or more,
This causes deterioration and damage of the resin sheet S, and lowers product quality.

The medium for controlling the temperature of the mold includes various oils,
Water and pressurized water (steam) are used, and it is desirable to use the same substance having different temperatures.

As described above, in the present invention,
The preform process of the resin sheet S can be performed by the same blow molding machine without using a separate device, and the surface in which the resin sheet and the core resin parison are fused and integrated in a very short cycle. It is possible to obtain a laminated blow-molded product having excellent properties.

[0029]

As described above, in the present invention,
By using the same blow molding machine to integrally mold the preformed resin sheet into the parison as it is, high-quality molded products with excellent transferability can be produced in large quantities without increasing cycle time. It can be produced efficiently.

[Brief description of the drawings]

FIG. 1 is an overall vertical sectional view of a blow molding machine according to an embodiment of the present invention.

FIG. 2 is a perspective view of a blow molding machine according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram showing an operation procedure of a lamination blow molding method according to an embodiment of the present invention.

FIG. 4 is a graph illustrating a mold temperature change in each step of the lamination blow molding according to the embodiment of the present invention.

FIG. 5 is an overall vertical sectional view of a conventional blow molding machine.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 blow molding machine 2 die head 2 a resin supply port 3 mandrel 3 a core 4 injection device 5 valve 6 paricon cylinder 6 a paricon rod 7 annular space passage 8 mold 8 a medium passage 8 b vent hole 8 c air injection hole 8 d air discharge hole 10 aggregate duct 11 exhaust pipe 12 solenoid valve 14 suction fan 16 pressurized fan 18 suction fan 20 roll 22 roll stand 24 sheet clip 30 cutter 30a air cylinder 30b cutter seat P parison S resin sheet h deaerating hole T die temperature T ₁ of the softening temperature t ₁ sheet set point t ₂ mold heating start point t ₃ preform end point (blowing step starting point) t ₄ cooling step starting point t ₅ the cooling step end point (product removal point)

Claims (3)

[Claims] 1. A hollow product is formed by sandwiching a resin sheet between a die head and a core attached to a lower end of a mandrel from an annular resin passage and sandwiching a resin sheet between a pair of left and right molds to form a hollow product. This is a lamination blow molding method, in which the mold is closed while the resin sheet is hung between the opened molds,
While the mold is heated to the softening temperature of the resin sheet, a preform process of a resin sheet in which air is blown into the mold cavity through a blow pin is performed, and until the temperature of the resin sheet reaches the softening temperature. Open the mold, discharge the parison while the resin sheet is fixed to the mold molding surface, hang it down, cool the mold until it reaches a temperature at which the molded product can be removed while closing and blowing. After that, the mold is opened and the molded product is taken out. 2. The bonding blow molding method according to claim 1, wherein the air injected into the mold cavity in the preform step is preliminarily heated to a temperature of 50 ° C. to 100 ° C. 3. The air blown into the mold cavity in the preform step is blown from one of a plurality of blow pins and discharged from any of the other blow pins. 2. The method for bonding blow molding according to 2.