JPH09267381A - Method for hollow molding and apparatus therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a large-sized hollow molding which is simple in structure and less expensive by a method in which a mold clamping apparatus having a fixed board and a movable board below a die head which discharges a parison is disposed, and the discharge position of the parison is controlled synchronously with the transfer of a movable side mold which is fixed to the movable board. SOLUTION: When a specified amount of a molten resin is stored in the tip part of an injection cylinder 6, a screw 5 advances, and a parison 36 is discharged from the discharge opening of a cross head 3 toward the center of an opened mold 24. At this time, the blowing nozzle 41 of an air blowing apparatus which is installed by penetrating the cross head 3 is inserted into the parison 36. At the completion of the discharge of the parison 36, a movable side mold 23 which is installed on the movable board 26 begins to close simultaneously with the movement, and the center of the parison 36 is transferred toward a fixed side mold 22 by a transfer synchronizing apparatus 9. When a mold 24 is closed completely, the parison 36, after being cooled by introducing air into it, is discharged from the mold 24 as a hollow molding.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hollow molding method and an apparatus thereof, and more particularly to a hollow molding method and an apparatus thereof for molding a large hollow molded article using a thermoplastic resin raw material. Is.

[0002]

2. Description of the Related Art Conventionally, a hollow molding apparatus for molding a large-sized hollow molding product is generally composed of an extruder, a hydraulically driven accumulator head attached to its tip, and a double-sided movable mold clamping plate. And a direct-acting type mold clamping device having. In the blow molding apparatus described above, the thermoplastic resin raw material melted and kneaded by the extruder is supplied to the storage chamber of the head. When a predetermined amount of molten resin is accumulated in this storage chamber, pressure oil is supplied to the cylinder provided above the head, the piston descends, and the molten resin in the storage chamber is discharged from the discharge port as a parison. The discharged parison is clamped by the mold attached to the double-sided movable mold clamping plate of the direct-acting mold clamping device, air is blown into the parison to cool it, and then it is discharged from the mold as a hollow molded product. To be done.

[0003]

Since the conventional blow molding apparatus is constructed as described above, it has the following problems. (a) A parison manufacturing apparatus using a combination of an extruder and an accumulator head requires high equipment cost, and the accumulator head is liable to retain molten resin and cause thermal decomposition, and has very good color exchangeability when changing raw materials. It was bad. (b) Since the mold clamping device is a direct-acting type mold clamping device that has a double-sided movable mold clamping plate, the hydraulic drive system requires multiple hydraulic cylinders, synchronizers, and piping, and also an electric motor drive. In the method, a complicated synchronizer and a large number of tie bars are required, so that the equipment cost is high.

The present invention has been made to solve the above-mentioned problems, and provides a hollow molding method and a device therefor capable of molding a large-sized hollow molding product, which has a simple structure and is inexpensive. The challenge is to provide.

[0005]

SUMMARY OF THE INVENTION In the present invention, a mold clamping device having a fixed plate and a movable plate is arranged below a die head for discharging a parison, and the movable plate is provided. It was solved by controlling the discharge position (die head position) of the parison in synchronism with the movement of the movable side mold attached to the. That is, according to the present invention,
Even if a single-sided mold clamping device is used for the hollow molding device, the parison does not hit the movable mold halfway when the mold is closed, and there is no hindrance to air blowing after the mold is fully closed, so it is inexpensive. It has become possible to provide a blow molding device.

[0006]

Embodiments of the present invention will be described.

In the blow molding method according to the present invention, a mold clamping device having a fixed plate and a movable plate is arranged below a die head for discharging a parison, and synchronized with the movement of a movable side mold attached to the movable plate. In addition, the discharge position of the parison is controlled.

A hollow molding apparatus according to the present invention is a mold in which a parison manufacturing apparatus having a die head at its tip and a mold clamping device having a fixed plate and a movable plate are attached to the mold clamping device below the die head. Is arranged so that
It is characterized in that the parison manufacturing apparatus is moved in synchronization with the movable side mold by a movement synchronizing device.

Further, the hollow molding apparatus according to the present invention comprises a parison manufacturing apparatus having a crosshead attached to the tip of an injection unit, and a mold clamping apparatus having a fixed plate and a movable plate.
The mold attached to the mold clamping device is arranged below the crosshead, and the parison manufacturing device is moved in synchronization with the movement of the movable mold by a movement synchronizing device. I am trying. When the blowing nozzle is provided below the mold, it is necessary to move the blowing nozzle by a movement synchronizing device in synchronization with the movement of the movable side mold.

[0010]

An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an overall schematic configuration diagram showing a blow molding device according to the present invention.

In FIG. 1, reference numeral 1 is a parison manufacturing apparatus, and this parison manufacturing apparatus 1 is composed of an injection unit 2 and a crosshead 3 which is a kind of die head attached to the tip of the injection unit 2. And pedestal 4
Is placed on top.

The injection unit 2 includes an injection cylinder 6 in which a screw 5 is rotatably and movably inserted.
A raw material hopper 7 for supplying a thermoplastic resin raw material into the injection cylinder 6, and a rear end portion of the injection cylinder 6,
The drive device 8 includes a hydraulic motor 8a for rotating the screw 5. The injection unit 2 can be moved back and forth by a movement synchronizing device 9, and can be turned by a turning device 10. That is, the injection unit 2 according to the present embodiment has substantially the same configuration as the injection unit of a general-purpose injection molding machine except the movement synchronization device 9.

An adapter 1 is attached to the tip of the injection cylinder 6.
A crosshead 3 is attached via 1. The crosshead 3 is provided with a cylinder 12 connected to the adapter 11, a longitudinally (vertically) extending center of the cylinder 12, and a manifold 13 at the outer peripheral portion.
A core 14 having a cylindrical shape, a core 15 provided at the lower end of the core 14, and a die 16 provided at the lower end of the cylinder 12, and an outer peripheral portion of the core 15. A discharge port is formed by a gap in the inner peripheral portion of the die 16.

Below the crosshead 3, a mold clamping device 21 having the following structure is arranged. That is, on the pedestal 4, a fixed plate 25 to which the fixed mold 22 is attached and a movable plate 26 to which the movable mold 23 is attached.
Are arranged so as to face each other, and an end housing 27 is arranged on the back side of the movable plate 26. The fixed platen 25 and the end housing 27 are connected to each other through four parallel tie bars 28 fixed at one end to the fixed platen 25, and the movable platen 26 is attached to the tie bar 28.
It is supported so as to be able to come into contact with and separate from the fixed platen 25. The end housing 27 is arranged on the gantry 4 via wheels,
A thread is formed at the end of the tie bar 28 on the end housing 27 side, and a tie bar nut (not shown) supported so as to be immovable in the axial direction with respect to the end housing 27 is meshed with this thread. ing. The tie bar nut is rotationally driven by the automatic die thickness adjusting device 29. By rotating the tie bar nut, the end housing 27 can be moved back and forth to adjust the distance between the end housing 27 and the fixed plate 25. That is, the automatic die-thickness adjusting device 29 enables automatic centering with respect to a change in the die core 24 due to the die thickness.

A toggle mechanism 30 for moving the movable platen 26 is provided between the end housing 27 and the movable platen 26. This toggle mechanism 30 includes an end housing 27.
The hydraulic cylinder 31 is fixedly attached to the piston, a cross head 32 fixed to the tip of the piston and moved in the axial direction, a toggle link 33 operated by the cross head 32, and the like. That is, the mold clamping device 21 according to this embodiment is the same as the mold clamping device of the injection molding machine.
Except for the fixed platen 25 and the mold 24, they have almost the same structure.

The hydraulic motor 8 of the drive unit 8 is installed in the frame 4 on which the parison manufacturing apparatus 1 and the mold clamping unit 21 are mounted.
A hydraulic unit 34 for supplying pressure oil to a and the like, and a hydraulic unit 35 for supplying pressure oil to the hydraulic cylinder 31 of the mold clamping device 21 are arranged. The crosshead 3 is arranged so as to be located above the mold 24 attached to the fixed platen 25 and the movable platen 26 of the mold clamping device 21.
When the parison 36 is discharged from the cross head 3 between the movable side mold 23 and the fixed side mold 22, and the movable side mold 23 moves toward the fixed side mold 22, the parison is moved to the movable side mold 23. In order to prevent the one-sided contact of 36, the parison manufacturing apparatus 1 is moved by the movement synchronization device 9 to the movable side mold 23.
The cross head 3 and the mold 24.
It enables automatic centering. It should be noted that the blowing nozzle 41 of the air blowing device may be provided so as to penetrate the crosshead 3 (not shown), but the blowing nozzle 4
When 1 is provided below the die 24, it is necessary to move the blowing nozzle 41 in synchronization with the movement of the movable die 23 by the movement synchronizer 42.

Next, the operation of the above-mentioned hollow molding device will be described.

When the thermoplastic resin raw material in the raw material hopper 7 is melted and kneaded by the screw 5 and supplied to the tip portion of the screw 5, the screw 5 is driven by the resin pressure.
Is retracted, and the molten resin is stored at the tip of the injection cylinder 6. When the molten resin is stored in a predetermined amount, the screw 5 advances, and the parison 36 is discharged from the discharge port of the crosshead 3.
It is discharged toward the center of the opened mold 24. At this time, the blowing nozzle 41 of the air blowing device provided penetrating the crosshead 3 is inserted into the parison 36. When the discharging of the parison 36 is completed, the movable side mold 23 provided on the movable plate 26 starts to close, and the parison 3
I try to crush 6. If the parison 36 comes into contact with only the movable mold 23, air blown after the mold is fully closed will be hindered. Therefore, the center of the parison 36 is moved in accordance with the movement of the movable mold 23. It moves to the fixed side mold 22 by. When the mold 24 is completely closed, air is blown into the parison 36 to cool it, and then the parison 36 is discharged as a hollow molded product from the mold 24.

In the embodiment described above, the parison manufacturing apparatus 1
Although the mold clamping device 21 is driven hydraulically, it may be electrically driven. In addition, the movement of the movable plate 26 is controlled by the toggle mechanism 3.
Although it is assumed that the operation is performed at 0, a linear motion mechanism may be used.

Further, when molding a particularly large hollow molding, the parison manufacturing apparatus 1 is used as a combination of an extruder and an accumulator head, and this is moved by the movement synchronizing device 9 in synchronization with the movement of the movable side mold 23. You may let me.

[0021]

Since the present invention is configured as described above, the following effects can be obtained. (a) When the parison manufacturing device is a combination of an injection unit and a crosshead, the injection unit can be manufactured by using the parts of the injection unit of a general-purpose injection molding machine, and the crosshead is an accumulator head. 80% of the price of conventional parison manufacturing equipment because it is cheaper
It can be manufactured in the following manner, and since the molten resin is less retained, thermal decomposition does not occur, and the color exchanging property at the time of changing raw materials is improved. (b) Since the mold clamping device can be manufactured by using the parts of the mold clamping device of a general-purpose injection molding machine having a movable platen and a fixed platen, a direct-acting type mold having a conventional double-sided movable mold clamping plate. It can be manufactured at 80% or less of the price of the fastening device.

[Brief description of drawings]

FIG. 1 is an overall schematic configuration diagram showing a blow molding device according to the present invention.

[Explanation of symbols]

 1 Parison manufacturing device 2 Injection unit 3 Crosshead (die head) 9,42 Movement synchronization device 10 Revolving device 21 Mold clamping device 22 Fixed side mold 23 Movable side mold 24 Mold 25 Fixed plate 26 Movable plate 36 Parison 41 Blowing nozzle

Claims (4)

[Claims] 1. A mold clamping device (21) having a fixed plate (25) and a movable plate (26) is arranged below a die head (3) for discharging a parison (36), and the movable plate (26) is provided with the mold clamping device (21). A hollow molding method characterized in that the discharge position of the parison (36) is controlled in synchronization with the movement of the attached movable side mold (23). 2. A parison manufacturing apparatus (1) having a die head (3) at its tip, a fixed plate (25) and a movable plate (2).
The mold clamping device (21) having 6) is arranged below the die head (3) so that the mold (24) attached to the mold clamping device (21) is located, and the parison manufacturing apparatus is provided. A hollow molding apparatus, wherein (1) is moved by a movement synchronization device (9) in synchronism with the movement of the movable side mold (23). 3. A parison manufacturing apparatus (1) in which a crosshead (3) is attached to the tip of an injection unit (2).
A mold clamping device (21) having a fixed platen (25) and a movable platen (26), and a mold (24) attached to the mold clamping device (21) below the crosshead (3). A hollow molding apparatus, which is arranged so as to be positioned so that the parison manufacturing apparatus (1) is moved in synchronization with the movement of the movable side mold (23) by a movement synchronization device (9). 4. The blow molding apparatus according to claim 2, wherein the blowing nozzle (41) is moved by a movement synchronizing device (42) in synchronism with the movement of the movable side mold (23).