JPH0481933B2 - - Google Patents

Description

Detailed Description of the Invention [Industrial Application Field] The present invention is an extrusion blow molding machine in which a flexible material is injected from a nozzle of an injection device into a gap between a mandrel as a core metal and a die outside of the mandrel. The present invention relates to a parison controller that allows a parison, which is a hollow molded product, to have a predetermined shape and thickness.

[Conventional technology]

An extrusion blow molding machine is known as a type of blow molding machine for producing hollow plastic products.
This type of extrusion blow molding machine is equipped with an injection device that has almost the same configuration as a general injection molding machine, and injects from the nozzle of this injection device into the gap between the mandrel as a core metal and the die outside of it. A flexible hollow preform called a parison hangs between the opened blow molds, is shaped into a predetermined shape by mold clamping, solidifies, and is then taken out as a hollow product. Ru.

In this type of molding machine, the size of the gap between the die and the mandrel determines the shape and wall thickness of the product, so this gap is adjusted prior to the molding operation.

[Problem that the invention seeks to solve]

However, in the past, the mandrel was moved in the axial direction manually, hydraulically, electrically, etc. to adjust the parison in the axial direction, and then a prototype was molded. This required a huge amount of man-hours and time, resulting in high costs and inefficiency, and in extreme cases, the mandrel had to be remanufactured.

[Means for solving problems]

In order to solve such problems, in the present invention, the mandrel is made to protrude from the die, and this protrusion is surrounded by a core having an inner peripheral shape that is roughly similar to the outer peripheral shape of the mandrel. A centering member is provided that can be moved and adjusted in each direction perpendicular to the axis, and a thin flexible cylindrical body whose upper end is fixed to the inner peripheral surface of the upper end of the core is placed between the core and the mandrel. The inner circumferential surface of the lower end of the flexible cylindrical body, which is positioned on the inner circumferential side of the lower end of the core and whose horizontal position can be adjusted, and the outer circumferential surface of the lower end of the mandrel. A resin outlet was formed between the two cores, and a screw member was screwed into the screw hole of the core so that the outlet could be adjusted partially and independently over the entire circumference by pushing and pulling.

[Effect]

The resin injected from the nozzle of the injection device into the gap between the mandrel and the die semi-solidifies and becomes a flexible hollow parison, which is then injected into the mold from the gap between the mandrel and the flexible cylindrical body outside its end. When the mold is clamped, the parison is crushed and a hollow molded product is obtained. Prior to such injection blow molding, when the centering member is adjusted, the core moves in each direction perpendicular to the axis of the mandrel, and centering with respect to the mandrel is performed. The flexible cylindrical body expands and contracts due to deformation, and the parison is corrected to a predetermined shape and thickness.

〔Example〕

1 to 4 show an embodiment of the parison controller according to the present invention, FIG. 1 is a partially cutaway front view of a mandrel and die implementing this, and FIG. 2 is a view of FIG. 1 from below. FIG. 3 is a partially cutaway front view of an extrusion blow molding machine embodying the present invention, and FIG. 4 is a partially cutaway side view showing the extrusion blow molding machine with the injection device removed. In the figure, an injection device, generally designated by the reference numeral 2, is mounted on a device frame 1, and this injection device 2 includes a cylindrical barrel 3 having a heating member, and an inner hole of the barrel 3 that rotates and A screw 4 fitted so as to be movable forward and backward, a hydraulic motor 5 for rotating the screw 4, and a barrel 3.
The injection cylinder 6 is provided with an injection cylinder 6 that moves forward and backward, and a hopper 7 that supplies resin pellets into the barrel 3. The resin supplied from the hopper 7 into the barrel 3 is heated and melted by a heating member and kneaded by the rotation of the screw 4. The tip of the barrel 3 is liquid-tightly supported by an accumulator 8 having a cylindrical shape with a bottom, and the molten resin extruded from the nozzle 3a of the barrel 3 into the accumulator 8 by the rotation of the screw 4 is transferred to the injection cylinder 6. It is configured to be compressed by the advancement of the barrel 3 and ejected from the nozzle 8a of the accumulator 8.

On the other hand, in front of the injection device 2, a mold device generally designated by reference numeral 9 is mounted on a machine base 10, and this mold device 9 is horizontally adjustable on the machine base 10. fixed bed 11
, the four corners are connected with tie bars 12 and the bed 11
A pair of mold clamping side plates 13 and 14 erected above and a mold clamping side plate 1 supported by the tie bars 12 so as to be movable forward and backward.
Square formworks 17 and 18 move forward and backward with formwork cylinders 15 and 16 on the 3 and 14 sides, and each of these formworks 1
A male mold 21 and a female mold 22 are fitted into the molds 7 and 18 so as to be freely movable and retractable, respectively, and are moved forward and backward by mold clamping cylinders 19 and 20 on the side of mold clamping side plates 13 and 14. Then, the molds 17 and 18 are adjusted forward and backward according to the sizes of the molds 21 and 22.
The mold is configured such that mold clamping and mold opening are performed by advancing and retracting the mold 22.

Above the mold device 9 configured in this way,
A die device, generally designated by the reference numeral 23, is disposed on the side of the injection device 2. This die device 23 is equipped with a die 24 whose inner circumference is formed into an oval rectangular bottomed cylinder shape that is elongated in the direction perpendicular to the mold clamping direction, and which opens downward.
It is fixed to the accumulator 8 via 5. The outer wall of the die 24 and the connection plate 25 are provided with resin passages 24a and 25a that are concentric with and communicate with the nozzle 8a of the accumulator 8. The piston rod 27 of the lifting cylinder 26 is located directly above the die 24 and supported on the device frame 1 side.
is inserted into the center of the die 24, and a mandrel 28 having an oval cross section is supported at its working end so as to be slidably fitted into the inner hole of the die 24. The mandrel 28 has a resin passage 2 concentric with and communicating with the resin passage 24a on the die 24 side.
8a and a radial resin passage 2 communicating with its terminal end.
8b, and between the outer periphery of the mandrel 28 and the inner hole of the die 24, an annular gap 29, which is a resin flow passage, is formed only below the resin passage 28b. Mandrel 28 is
It protrudes downward from the lower open end of the die 24, and around this protrusion, a parison controller, generally designated by the reference numeral 30, is provided. The parison controller 30 includes a presser plate 31 fixed to the lower end surface of the die 24. The presser plate 31 has a rectangular outer circumferential shape with the same dimensions as the die 24, and an inner circumferential shape similar to the mandrel 28. It is formed into a similar oval shape. Reference numeral 32 is a core as a centering member formed in an oval annular shape, and is supported by engaging the presser plate 31 and the flange portions so as to surround the mandrel 28, and this outer peripheral shape is the same as that of the presser plate. It is formed into an oval shape similar to the inner circumference of the plate 31 and slightly smaller than this. The inner peripheral shape of the core 32 is similar to that of the mandrel 28.
It is formed into an oval shape that is similar to and larger than the outer circumferential shape of . The holding plate 31 has a total of six centering bolts 3, two on each long side and one on each short side.
3 is screwed into the core 32 with its tip in contact with the outer circumferential surface of the core 32, and by selecting some of the centering bolts 33 and moving them forward or backward, the core 32 can be moved in horizontal directions, front and back, right and left. The core 32 and the mandrel 28 are configured to be centered. Furthermore, between the core 32 and the mandrel 28, PP,
A liner 34 is a thin oval-shaped cylindrical body made of synthetic resin such as PE, ABS, or vinyl chloride, or a flexible material such as hard rubber or spring steel. Retained and interposed.
Between the liner 34 and the mandrel 28, there is a resin passage 25 injected from the nozzle 8a.
A gap t is formed through which the resin flowing down the gap 29 continues to flow down due to the diameters a, 24a, 28a, and 28b. Reference numeral 35 is an adjustment bolt screwed into a position that divides the entire circumference of the core 32 almost equally, and its tip is brought into contact with the liner 34, and by selectively moving some of them forward or backward, the liner can be adjusted. 34 is deformed to expand and contract, and the gap t is adjusted at a plurality of corresponding locations on the adjustment bolt 35. What is indicated by the reference numeral 36 in the figure is a hollow parison formed of resin hanging from the gap t,
The parison 36 is suspended between the molds 21 and 22, and is configured so that the shape and thickness of the parison 36 can be adjusted by adjusting the gap t using the adjustment bolt 35. Furthermore, the piston rod 27 of the lifting cylinder 26 is fitted with a nut 3 screwed into the threaded portion thereof.
It is fixed to the die 24 by 7 and 38,
Loosen these nuts 37 and 38 and lift cylinder 26.
The gap t between the mandrel 28 and the liner 34 is adjusted uniformly over the entire circumference according to the thickness of the molded product by moving the piston rod 27 forward and backward with the hydraulic pressure. 39 is a die gap detector that detects the size of the gap t based on the amount of movement of the piston rod 27, and 40 is a servo valve that cooperates with the die gap detector 39 to control the size of the gap t.

The operation of the extrusion blow molding machine configured as above will be explained. When resin is supplied from the hopper 7 into the barrel 3 and the hydraulic motor 5 is rotated, the barrel 3
The resin melted and plasticized by heating is kneaded by the rotating screw 4 while passing through the nozzle 3.
It is extruded from a into the accumulator 8 and filled into the accumulator 8 at a predetermined density. Therefore, when oil is sent to the rod end side of the injection cylinder 6 and the barrel 3 is advanced together with the screw 4, the resin filled in the accumulator 8 is transferred to the nozzle 8a.
The resin is injected from the resin passages 25a, 24a, 28.
a, 28b, and is led to the gap 29, where it flows down uniformly over the entire circumference. This resin further flows down through the gap t between the mandrel 28 and the liner 34, forms a parison 36, and hangs down between the molds 21 and 22 which are being opened. Note that the lower end of the parison 36 is closed as a result of being cut by grippers (not shown) in the previous injection cycle. When the parison 36 is hung down, the formwork cylinder 1 is cut in advance according to the dimensions of the parison 36.
Both molds 2 in the formwork 17 positioned by 6
1 and 22 are simultaneously moved forward and clamped by mold clamping cylinders 19 and 20. As a result, parison 36
is molded into a cavity shape, resulting in a hollow molded product.

In such a molding operation, parison control is performed prior to the operation. First, the mandrel 28 is slightly raised and lowered by operating the lifting cylinder 26 according to the wall thickness of the product, and some of the centering bolts 33 are selected and moved back and forth, thereby reducing the gap t between the mandrel 28 and the liner 34. Make rough adjustments to the specified dimensions all around the circumference. Next, when some of the adjustment bolts 35 are selected and moved forward or backward, the liner 34 is deformed in at least one of the circumferential direction and the axial direction, and the gap t is
Fine adjustments are made for each location corresponding to 5. As a result, the hanging parison 36 has a predetermined shape and thickness, and therefore the molded product also has a predetermined shape and thickness.

In this embodiment, the liner 34 is held on the core 32 side, the adjustment bolt 35 is screwed into the core 32 side, and the gap t is provided on the mandrel 28 side. , and screw the adjustment bolt 35 into the mandrel 28 side.
A gap t may be formed between the liner 34 and the core 32.

Furthermore, in the embodiment described above, the axes of the die 24 and the mandrel 28 are vertical, the molds 21 and 22 are clamped laterally, and the parison 36 is suspended downward. However, in the present invention, the axes of the die 24 and the mandrel 28 are oriented in the horizontal direction, and the molds 21 and 22 are
It can also be applied to systems in which the parison 36 is flowed out horizontally or diagonally, such as a system in which the parison 36 is clamped vertically and its tip is grabbed by a pinch device and flows out horizontally.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, in the parison controller of an extrusion blow molding machine, the mandrel is made to protrude downward from the die, and this protrusion has an inner peripheral shape that is approximately similar to the outer peripheral shape of the mandrel. A centering member is provided which is surrounded by a core and moves and adjusts the core in various directions perpendicular to the axis of the mandrel. A thin flexible cylindrical body is interposed between the mandrel and the resin passage space, and the lower end of the flexible cylindrical body is located on the inner circumference side of the lower end of the core, and the horizontal position can be adjusted. A screw member is screwed into the screw hole of the core to form a resin outlet between the inner circumferential surface of the core and the outer circumferential surface of the lower end of the mandrel. As a result, when the centering bolt is moved forward or backward, the mandrel and the core are centered, and when the screw member is pushed or pulled, the cylindrical body deforms, expands and contracts, and flows out from the gap inside or outside the cylindrical body. Since the parison, that is, the shape and wall thickness of the product, is adjusted, parison control can be performed quickly and accurately with a simple configuration, which can significantly reduce equipment costs, reduce man-hours, and improve work efficiency. .

[Brief explanation of the drawing]

1 to 4 show an embodiment of a parison controller for an extrusion blow molding machine according to the present invention,
Fig. 1 is a partially cutaway front view of a mandrel and die in which this invention was implemented, Fig. 2 is a plan view of Fig. 1 seen from below, and Fig. 3 is a part of an injection blow molding machine in which the present invention is implemented. FIG. 4 is a partially cutaway side view with the injection device removed. 2... Injection device, 3a, 8a... Nozzle, 8...
...Accumulator, 9...Mold device, 21...Male mold, 22...Female mold, 23...Dice device, 2
4...Dice, 28...Mandrel, 29...Gap, 30...Parison controller, 31...
Holding plate, 32... Core, 33... Centering bolt,
34...liner, 35...adjustment bolt, 36...
Parison, t...Gap between mandrel and liner.

Claims (1)

[Claims] 1 An extrusion blow molding machine in which a flexible hollow parison is injected from the nozzle of an injection device into the gap between a mandrel and a cylindrical die outside the mandrel, and is positioned between molds and molded into a predetermined shape by clamping the mold. In,
The mandrel is made to protrude beyond the die in the axial direction, and this protrusion is surrounded by a core having an inner circumferential shape roughly similar to the outer circumferential shape of the protruding part, and the core is adjusted by moving in each direction perpendicular to the axis of the mandrel. A thin flexible cylindrical body whose upper end is fixed to the inner peripheral surface of the upper end of the core is provided between the core and the mandrel, and a thin flexible cylindrical body is provided between the core and the mandrel during the passage of the resin. Interpose by setting up
A resin outflow port is formed between the inner circumferential surface of the lower end of the flexible cylindrical body located on the inner circumferential side of the lower end of the core and the lower end outer circumferential surface of the mandrel and the outer circumferential surface of the lower end of the mandrel. A parison controller for an extrusion blow molding machine, characterized in that a screw member is provided which is screwed into a hole and allows the outlet port to be adjusted partially and independently over the entire circumference by pushing and pulling.