JPS5827093B2 - Hollow body forming equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for molding a synthetic resin hollow body.

Conventionally, two methods have been used as blow molding methods: extrusion blow molding method and injection blow molding method.

Of these, the latter has advantages such as a beautiful finish at the bottom of the hollow body and a low scrap generation rate, but it requires high equipment costs and mold prices, and also has limitations on the shape of the hollow body to be molded, such as the inability to mold narrow-mouth bottles. It had the disadvantage of being

On the other hand, in the former method, that is, the extrusion blow molding method, the bottomless parison extruded from the die is pinched and sealed by the pinch part of the mold, and then fluid is blown into the parison to form a hollow body. They usually left ugly seal marks and were weak in strength.

Additionally, excess parison is generated outside the pinched portion of the mold, which causes a significant decrease in material efficiency.

The present invention has been made from the viewpoint of correcting the above-mentioned drawbacks, and is intended to cut the parison during the process from when it is extruded from a die to when it is sandwiched between molds, or after it is sandwiched between molds, and to attach one end of the parison to the bottom. The characteristic of this method is that the bottoming is done at a position away from the die exit and extending in the extrusion direction.

Conventionally, when forming a parison bottom, a method has been known in which tools that are closely matched are butted against each other from the inside and outside of the bottom.

It is clear that by using tools that closely match each other, it is possible to form the bottom of a hollow body with good appearance and strength without leaving any sealing marks.

However, in the conventional method, the bottom of the parison is attached at the exit of the die, such as Japanese Patent Publication No. 474149, but there are various difficulties in putting this into practical use, and it is not actually used.

The reason for this is as follows.

(1) When filling the sealed space between the die tip and the mold with resin by directly pressing a mold with a space corresponding to the bottom of the parison against the die outlet, insufficient or overfilling may occur. many.

It is necessary to supply the resin by a feeding mechanism and to stop the supply of the resin the moment an appropriate filling state is reached, or to remove the mold while continuing the supply of the resin.

The former method is similar to that performed in ordinary injection molding, but in this case, the resin is discharged from the die discontinuously, resulting in poor productivity and complicated operations.

Therefore, it is preferable to adopt the latter method in order to bring out the advantages of extrusion blowing, but in this case, it is difficult to control the timing of mold removal.

(2) The die must be kept at a high enough temperature to allow sufficient flow of the resin.

In addition, if a mold with a space corresponding to the bottom of the parison is not released quickly after the above-mentioned filling operation is completed, the parison cannot be extruded with the bottom and the parison connected. The contact area, ie, the tip of the mandrel, must be kept at a low enough temperature to allow release from the mold.

It is difficult to maintain such significantly different temperatures within the same die.

Although it is different from the method of the above patent, it is also possible to isolate and thermally insulate the die and the bottom molding part as is done in normal injection molding, but in this case, the bottom molding part can be separated and thermally insulated from the molding part after molding. This requires cooling time, resulting in poor productivity similar to that seen in injection blow molding.

For the above reasons, cutting and bottoming of the parison is performed at a position farther from the die exit and extending in the extrusion direction than at the die exit, that is, the parison is cooled by being exposed to the outside air to some extent, and the above-mentioned bottoming that touches the parison is performed. It is reasonable to perform this at a location where the means can be sufficiently cooled.

That is, when cutting the parison and sealing the bottom at the above-mentioned position, a sealing tool that moves from the outside of the parison toward the center and is brought into contact with the parison, and the tip of an extended mandrel that comes into direct contact with the parison is used. The bottom molding tool can be cooled by water circulation or other means, and the tool can be easily released from the Halinon bottom after molding.

In the usual molding method, the parison is first held between the parison holding tools or a mold, the parison is cut immediately above the holding position, and the parison holding tool or mold is immediately released downward or to the side.

In a normal method, the above-mentioned holding and cutting of the parison is carried out in a stationary position without moving in the direction of movement of the parison, so there is no need to move between the parison, which is constantly moving in the extrusion direction, and a stationary cutting device or holding device. A relative positional change occurs.

In other words, if a period of time P elapses after Balinone is held until cutting is performed, the parison will sag and the cutting will not be performed properly.

Furthermore, if the timing of release of the parison holding tool or the mold holding the parison is delayed after cutting the parison, the lower surface of the succeeding parison that has been cut at the time comes into contact with the upper surface of the preceding and separated parison and is fused again.

The present invention has been made in consideration of eliminating the above-mentioned drawbacks and also securing sufficient time for forming the bottom part.

That is, while the parison is being continuously extruded, the parison holding device provided immediately after the cutting position moves with the parison cutting device at substantially the same speed and in the same direction toward the direction of movement of the parison at least during the cutting period of the parison. Since the parison is movable and the relative distance between the parison holding position and the cutting position is kept constant, it is possible to prevent cutting defects caused by sagging of the parison.

Further, after the parison is cut, the parison holding device is moved so as to increase the relative distance from the parison cutting device, so that the lower surface of the following parison and the upper surface of the preceding and separated parison are re-welded to each other. The end face of the parison can be kept in good condition after cutting.

The above explanation deals with the case where a device for holding the parison is provided separately from the mold, but there is no problem in holding the parison directly at the neck of the mold cavity, and in this case, the parison holding device is considered to be replaced by the mold. good.

Next, a parison cutting device, a parison forming device for sealing used to make the end face of the parison bottomed, and an extension mandrel provided through the die are used to cut the parison in the direction of movement of the parison extruded from the die. If the parison is moved at substantially the same speed and in the same direction as the moving speed, the excess length of the parison covering the tip of the extended mandrel can be kept constant at the required length.

Keeping the above-mentioned surplus length constant ensures that the space created between the tip of the extension mandrel and the butting tool that faces it while being butted is filled with an appropriate amount of material, neither insufficient nor excessive. This is extremely important.

According to the present invention, the amount of resin filled in the space between the tip of the extension mandrel and the butt tool can be made constant and almost the same as the volume of the space, so when molding laminated parnon in multilayer blow molding. Particularly effective.

In other words, when bottoming is performed at the die exit in extrusion blow molding, even if multiple resins are simultaneously poured into the space surrounded by the mold corresponding to the bottom of the hollow body prior to extrusion of the body of the parison, the final resin will be It is impossible to prevent the layer from being disturbed at the part where it is completely filled, that is, at the bottom.

This is because when bottoming is performed at the die exit, body forming and bottom forming are repeated discontinuously at the die outlet.In particular, when bottom forming, low viscosity resin covers high viscosity resin. The weld area at the center of the bottom, which tends to flow and eventually fills, is often composed only of low-viscosity resin.

In any case, when multiple resins are simultaneously poured into a closed mold, it is difficult to form a continuous layer with a uniform thickness and a multilayer structure with an orderly arrangement order. .

On the other hand, in the case of this forming method, the die discharge part is always kept under the same conditions, and once extruded as an orderly layered cylindrical body, the parison extruded as an ordered layered cylindrical body has an excess or deficiency in volume. Since the material is only subjected to drawing deformation in the secondary processing in the space without any space, the order such as the arrangement and continuity of the layers formed during continuous extrusion can be well preserved.

Furthermore, in the molding apparatus of the present invention, trimming losses, which amount to more than 30% of the total throughput, which are found in conventional extrusion blow molding apparatuses, can be kept within a few percent.

In the multilayer blow molding method, the trimmed scrap is made up of many different types of resin, so it is difficult to recover and reuse it, which significantly reduces the raw material utilization efficiency of multilayer blow molding. According to the invention, all of the above-mentioned difficulties can be improved.

Of course, it goes without saying that even in single-layer blow molding, a reduction in trimming loss increases the production capacity of the molding machine and reduces scrap recovery costs, which has the effect of lowering manufacturing costs.

Embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an example of an apparatus for single-layer blow molding using one extruder.

1 is a molding machine frame.

Reference numeral 21 denotes a screw extruder for supplying resin, and the resin supplied from the hopper 211 is advanced in a cylinder (not shown) by the feeding action of a screw (not shown), and is passed from the die head 212 to the nozzle 2.
13 and into the die 3.

During this time, the resin is heated and plasticized by the Retaband heater provided around the outer periphery of the cylinder.

The screw extruder 21 has wheels (not shown) attached to the lower surface of its support base 214, and is configured to be able to move in the screw axial direction on the support stand 11 of the molding machine frame 1 while being guided by rails.

FIG. 2 shows an apparatus for forming multilayer parisons using multiple extruders.

In this case, in addition to the screw extruder 21 described above, an auxiliary extruder 22 is additionally provided.

The auxiliary screw extruder 22 plasticizes and supplies raw materials different in type or color from the screw extruder 21, and both have similar configurations of their main parts.

In other words, the resin supplied from the hopper 221 is fed into the cylinder by the feeding action of the screw! The nozzle 22 advances through the die head and is plasticized during the process.
2 and is sent into the die 3.

The auxiliary semi-fluid extruder 22 differs from the screw extruder 21 in the method of supporting its extrusion unit.

In the auxiliary screw extruder 22, an extrusion unit 223 is mounted on a support 224, and a trolley 225 is provided at the lower end of the support 224, and wheels 226 are attached to the lower surface of the trolley to allow for freedom of movement as a structure. There is.

1 and 2, a molding machine frame front plate 12 is provided on the front side of the molding machine frame 1, and a bracket 121 for supporting various mechanisms of the parison molding section is provided on the front plate.

FIG. 3 shows the detailed structure around the bracket part.

The bracket is further provided with a wand guiding cylinder 122 and a top plate 123.

Reference numeral 13 denotes a reciprocating assembly that descends in synchronization with the descending speed of the parison, rises after the required operation is completed, and repeats the above operation.

The guide bar 131 of the reciprocating assembly 13 is inserted into the guide cylinder 122 and is slidably supported in the axial direction of the cylinder.

A connecting plate 132 is provided at the upper end of the guide bar 131 and is fastened with a tightening nut 133.

The lower end is also connected to the bottom forming device 4 and the cutting device 5 to form an integral reciprocating assembly.

The mandrel 31 is inserted through the center of the connecting plate 132.
The rear part of the connector is inserted and fastened with a nut 134.

Further, the rear end portion 311 is provided with a male thread.

The top plate 123 of the bracket is provided with a rotary female screw 141 passing through the top plate, and is freely rotatable with respect to the top plate.

Numeral 142 is a nut for positioning the above-mentioned rotating female screw 141 in the axial direction with respect to the top plate 123.

Reference numeral 143 denotes a bevel gear, which is fitted onto the rotary female thread 141 by a key (not shown) so as not to rotate relative to the female thread 141, and is fastened with a nut 144.

145 is a bevel gear, which is similar to the bevel gear 144 described above.
meshes with

Reference numeral 146 denotes a forward/reverse rotation switching clutch, and the direction of rotation of the rotary shaft driven by the variable speed motor 147 with a reduction gear can be arbitrarily switched to clockwise or counterclockwise by actuation of the clutch.

Since the male thread of the mandrel rear end 311 is screwed into the rotary female thread 141, the variable speed motor 14 with a reduction gear
The drive by 7 rotates the rotary female screw 141 through the forward/reverse rotation switching clutch 146 and bevel gears 145, 144, and is converted into vertical movement of the mandrel 31.

The rear portion of the mandrel 31 is fastened to a connecting plate 132, and the reciprocating assembly 13 is coupled to the connecting plate 132, so that the assembly reciprocates together with the mandrel 31.

FIG. 4 shows the relative positional relationship between the die 3, the molding device 4, the cutting device 5, and the parinon holding device 6.

In this example, the case of two-layer parison extrusion shown in FIG. 2 was shown, but in the case of single-layer parison extrusion shown in FIG. There is no difference from the figure.

In Fig. 4, 212 is the die head of the main screw extruder 21, 213 is the nozzle, and 214 is the screw 215
216 indicates a cylinder, and 216 indicates a breaker plate.

Further, 229 is a die head of the sub-screw extruder 22;
Similarly, 22 is a nozzle, 227 is a screw, 228 is a cylinder, and 230 is a breaker plate.

The die 3 includes a mandrel 31, a first die ring 33, a second die ring 34, and a third die ring 35.

The resin supplied from the main screw extruder 21 is sent to the nozzle 2
13, a manifold 341 and a cylindrical flow path 342 formed between the second die ring 34 and the third die ring 35.
flows into and forms an external flow.

The resin supplied from the sub-screw extruder 22 is transferred to the nozzle 2.
22, a manifold 331 formed between the first die ring 33 and the second die ring 34, and a cylindrical flow path 332.
and forms an internal flow.

The two flows are merged at a confluence point 36 and enter a common flow path 37 to form a two-layer flow.

In this embodiment, a parison die forming two layers is shown, but the number of layers may be a single layer or a multilayer of three or more layers.

The center of the first die ring is a cylindrical cavity,
The protrusion 312 of the mandrel 31 comes into contact with the inner surface of the mandrel 31 so that it can slide in the axial direction.

Further, as shown in FIG. 6, the mandrel rear end 311 is provided with an air nipple 313, an air hole 314, cold water nipples 315, 318, and cold water holes 316 and 317.

The tip of the mandrel 31 is an extended mandrel 32, the tip of which has a hemispherical shape.

A mushroom valve 321 is provided at the tip of the extension mandrel 32.

The tip of the mushroom valve 321 has a conical shape, and a piston 325 is inserted into the rear end and is fixed with a nut 326.

The piston 325 is fitted into a cylindrical cavity 327, and a spring 322 applies pressure in a direction to close the conical portion.

The mushroom valve 321 has ventilation holes 3 in its center and in the radial direction.
23,324 are provided.

If air is blown from the air nipple 313,
Air passes through the air hole 314 and reaches the cylindrical cavity 327, where air pressure acts on the piston 325 to push down the mushroom valve.

Further, at the same time as the valve opens, the air accumulated in the cavity 321 leaks to the outside of the extension mandrel 32 through the vent holes 323 and 324 and between the valve seats.

In Fig. 4, numeral 38 indicates a parison whose bottom part has been molded.
and the tip of the extended mandrel 32, and promotes mold release between the parison 38 and the tip of the mandrel.

Further, the cold water entering the cold water nipple 315 in FIG. 6 is discharged from the cold water nipple 318 through the cold water holes 316 and 317.

During this time, the interior of the extension mandrel 32 is cooled and serves to prevent the resin forming the parison 38 from sticking to the extension mandrel 32.

Therefore, it becomes easier to release the parison 38 from the extended mandrel 32.

4 is a molding device for the Halinon bottom.

41 is a casing of the molding device, 411 is a casing body, 412 is a casing top cover, and 413 is a casing bottom cover.

The casing body 411 has a partition wall 414, and the partition wall 414 is provided with grooves 415 in the radial direction, and the casing lid also has similar grooves 4 at positions corresponding to the grooves.
16 are provided.

Further, the casing body is provided with a support ear portion 417 facing outside, and a hole 418 is provided through the support ear portion 417.
The lower end of the guide bar 131 is inserted into the nut 135.
is fixed.

The center of the partition wall 414 is a cylindrical bearing 419, into which a grooved cam gear 421 is rotatably fitted.

422 is a cam groove provided on the gear, and 423 is a tooth of the gear.

424 is a torque actuator driven by hydraulic or pneumatic pressure, and 425 is a small gear mounted on the torque actuator drive shaft.

A guide groove 431 is provided in the lower part of the partition wall 414 in the radial direction, and a tool 432 for sealing the parison is housed so as to be slidable in the radial direction.

Further, a tool 433 for suppressing the parison is housed in a direction perpendicular to the tool 432 so as to be slidable in the radial direction.

The tool 432 for sealing the parison and the tool 433 for suppressing the parison are provided with pins 434 and 435 on their upper parts, which penetrate through the grooves 415, cam grooves 422, and grooves 416, so that the outer surface of the pin meets the inner surface of the groove. It is designed so that it can slide in contact with it.

What is shown in FIG. 5 is a state in which the sealing operation is being performed, and shows the extreme state in which the torque actuator 424 rotates counterclockwise.

In this case, the tool 432 for sealing the parison and the tool 433 for suppressing the parison have moved toward the center of the molding device, and their tips are in a closed state.

Once the sealing is completed, the torque actuator 424
operates clockwise when viewed from the direction of FIG. 5, but the small gear 425 directly connected to the torque actuator rotates clockwise, and the gear 421 meshing with the small gear rotates counterclockwise, and the pin 434 rotates clockwise. .435 is guided by the cam groove 422 and moves radially outward from the axis of the forming device.

A tool 432 that seals the parison fixed to the pin at the same time as the pin moves outward, and a tool 43 that suppresses the parison.
3 similarly moves outward in the radial direction and becomes open.

By repeating these operations, the parinon bottom is formed.

Note that the tool 433 for suppressing the parison comes close to each other when forming the bottom of the parison (the tool 432 for sealing the parison)
The sealing tool 4320 is provided to prevent the cut end of the parison from protruding from the side surface of the opposing cavity, that is, the hemispherical part, and the cut end of the parison that protrudes from the surface connecting the edges of the opposing cavities of the sealing tool 4320. This functions to narrow the area inward.

By doing the above, not only does scrap generation due to pinch-off that occurs when the parison is cut off at the pinch part of the mold occur, but also the bottom part can be molded without disturbing the orderly arrangement of the layered parison layers. I can do it.

In this case, the cutting length of the parison is such that the cut parison is connected to the tip of the extension mandrel 32 and the tool 432 that seals the parison.
It is necessary to make the length so that it fills the space formed by it and does not create excess or deficiency.

By doing this, the Harinon bottom part will not protrude beyond the sealing tool 432, and there will be no shortage of filling (and since the male and female molds are mate-molded, a bottom part with uniform wall thickness and good appearance can be molded. .

7 and 8 show the cutting device 5. FIG.

Reference numeral 51 denotes a cutting device holding portion, which is fixed relative to the bottom forming device 4.

511 is a holding plate, which is attached to the casing body 411 of the forming device 4 by bolts 512.

A guide bar 513 is attached to the holding plate 511 and tightened with a lug nut 514.

52 is a reciprocating portion.

521 is a slide piece, and a hole 52 provided in the iron piece
2 fits into the guide bar 513 and can slide in the axial direction.

523 is a connecting plate, and -i is an air cylinder 53
It is fixed to the rod 532 of.

533 and 534 are nuts for fixing.

Reference numeral 531 indicates an air cylinder main body, and reference numerals 535 and 536 indicate an air cylinder base, which is fixed to the rear part 515 of the holding plate.

524 is a cutting blade.

The connecting plate 523 is connected to the sliding piece 521 by the bolt 525.
is obsessed with.

54 is a current supply device.

541 is a bolt, 542 is an insulating tube, and 543 and 544 are insulating washers.

The cutting blade 524 is POL) 541. It is attached to the slide piece 521 via a nut 545.

Further, a current-carrying wire 546 is attached to the other end of the bolt 541, and is fixed with nuts 547 and 548.

The energization is performed to heat the cutting blade 524, and is particularly suitable for cutting low-viscosity resins such as polypropylene and nylon.

44 is a stopper provided on the lower surface of the molding device 4.

This stopper 44 is located on the lower surface of the bottom cover of the casing and needs to be provided outside the region traversed by the reciprocating section 52.

9 to 11 show the parison holding device 6. FIG.

The base plate 61 of the parinon holding device includes a base plate main body 611 and a support plate 612 provided perpendicularly thereto.
It becomes more.

An air cylinder 613 is attached to the support plate 612.

A slide plate 62 is provided on the upper surface of the base plate main body 611 and is capable of reciprocating by sliding on the iron surface.

A fulcrum pin 622 is provided on the slide plate substrate 621 to support the arm 631.

The fixing bolt 623 fixes the arm 631 so that it can freely rotate around the fulcrum pin.

One end of the arm is rotatably connected to the connecting rod 632 by a connecting pin 624 and fixed by a locking bolt 625.

The other end of the connecting end of the connecting rod 632 is connected to the moving end 633 by a connecting pin 626 and fixed by a locking bolt 627.

The moving end 633 is fixed to the tip of the rod 614 of the air cylinder 613.

Reference numeral 634 is a suffling whose both ends are fixed so as to hold two connecting pins, and tension is applied in a direction to draw the two pins together.

A engagement device 64 is provided in a part of the slide plate 62.

That is, the cylinder 6 is placed on the top surface of the slide plate substrate 621.
41, into which a fitting piece 642 is inserted so as to be slidably fitted to the inner surface of the cylinder.

In addition, there is a position adjustment piece 643 at the top, and a lid 64
Covered by 4.

A spring 646 is inserted between the engagement piece 642 and the position adjustment piece 643, and the pressing force of the spring can be adjusted by adjusting the pressing bolt 645.

616 is the engagement piece 6 at the forward position of the slide plate.
This is a notch that fits into the protrusion of 42.

Further, 617 is a stopper for regulating the forward limit position of the forward position of the slide plate.

The slide plate base plate 621 is guided by the holding side plate 615 and reciprocates in the axial direction of the air cylinder 613.

65 is a chuck for holding the parinon.

The vacuum chamber 651 consists of an annular chamber divided into two parts, and a suction hole 652 is provided on the inner surface thereof.

A nipple 654 is provided on the outer surface of the vacuum chamber 651, and air is evacuated from a vacuum source (not shown) via a rubber tube 655.

The operating sequence shown in Fig. 9 is the chuck 6.
5 is in the closed state.

In this case, the rod 614 of the air cylinder, that is, the moving end 6
33 is in the forward position.

Now, when the rod begins to retreat, the spring 634 begins to contract and the connecting pins 624 move closer to each other (so the arm 631 rotates around the fulcrum pin 6220 and the chuck opens).

Subsequently, when the rod 614 is further retreated, the engagement device 64
The engagement piece 642 is disengaged from the notch 616, and the slide plate 62 and the chuck 65 are also moved back.

During the retraction process and the retraction position, the spring 634
is contracted, so the chuck is always open.

When the rod 614 starts moving forward after a certain period of time has elapsed, the slide plate 62 moves forward together with the chuck open, and when the tip of the slide plate base plate 621 hits the stopper 617, the slide plate 62 stops moving forward.

At this time, the engagement piece 642 of the engagement device 64 engages with the notch 616.

Subsequently, when the rod 614 moves further forward, the sufling 6
34 and the connecting pins move away from each other, so the arm 631 rotates around the fulcrum pin 6220 and the chuck closes.

The above operations are repeated.

FIGS. 12 and 13 show a parison carriage device 7,
The mold clamping device 8 is shown.

The base plate main body 611 of the Halinon holding device is joined to the follower 711 of the carriage device main body 71.

712 is a frame of the carriage device main body 71.

One end of the frame 712 faces the follower 711, and the frame 1 nongua 13 is inserted between the frame 712 and the follower.

The spring 713 functions to apply force in the direction of pressing the follower.

The follower 711 is provided to freely reciprocate in the axial direction of the spring 713 on the frame 71 of the carriage device main body by a sliding guide mechanism (not shown).

Further, wheels 714 are attached to the follower 711.

124 is a cam plate attached to the front plate 12 of the molding machine frame 1.

A guide plate 715 is attached to the carriage device main body 71.

The guide plate 715 is sandwiched between a pair of rollers 1510 provided on the rear plate 15 of the frame.
The surface of 51 is supported so that it can be moved freely by lightly contacting the guide plate.

A mounting plate 71 is provided on the back of the carriage device main body frame 71.
6 protrudes and is connected via a pin 718 to a rod 722 of the hydraulic cylinder 72 and a connecting piece 717 provided at the tip.

721 is a hydraulic cylinder main body, and 723 is a rotatable support end.

A fixed end 124 is fixed to the molding machine frame 1.

Further, the fixed end 724 is rotatably supported by the support end 723 and the pin 725.

12 and 13 show the carriage device main body 71 in its most advanced position.

That is, hydraulic cylinder 720 and rod 722 are in the forward position.

When the rod 722 of the hydraulic cylinder begins to retreat, the carriage device main body 71 moves toward the guide plate 7 held between the rollers 151.
The driven wheel 714 fixed to the follower is guided by the cam plate 124 while the follower 711 slides on the contact surface with the frame 712. and moves in the axial direction of the spring 113.

Base plate body 611 of Parinon carriage device I
is fixed to the follower 711 described above, the locus of movement of the cross-sectional center of the base plate main body 611 is shown by a two-dot chain line 125.

Note that it is desirable that the trajectory 125 described above is the same as the direction of movement of the bottom forming device 4 and the cutting device 5 at the beginning of the movement.

The locus 125 also moves the mold 8 at the end of its movement.
Although it is desirable that the surface be parallel to the top surface of 1, the latter is not necessarily an essential condition.

In FIG. 13, the most retracted position of the carriage device main body 71 is shown by a two-dot chain line.

A base plate 61 is attached to the front plate 12 of the molding machine frame.
It is necessary to provide a sufficient number of notches 126 to allow the movement along the trajectory 125 described above.

A mold 81 is attached to the mold clamping device 8 .

811 is a mold body divided into two parts, and 812 is a mold cavity that forms the outer mold of the container.

Reference numeral 813 indicates a front platen, and 814 indicates a rear platen, to which the two mold bodies 812 divided into two are attached.

815 is a connecting platen for connecting two tie bars 816 to each other.

Also, 817, 818, and 819 are the rear platen 8, respectively.
14, the tie bar 81 passes through the front plate 12 and the rear plate 15
This is a bush to support 6.

Of these, the bushing 817 is attached to the tie bar 81 as shown in the figure.
It extends long in the axial direction of 6 and is used for guiding the tie bar.

82 is a mold moving mechanism.

821 is a hydraulic cylinder attached to the front plate 12,
The rod 822 is attached to the rear platen 814.

Behind the rear platen 814 is a rear platen rack 82.
3 is also connected to the connecting platen 815, and the connecting platen rack 8
24 is the tsuke.

A boss 127 is provided at the lower end of the cam plate 124, and a pinion 825 is attached to the end of the boss 127.

The aforementioned racks 823 and 824 face each other and mesh with a pinion 825.

826 is a bolt that restricts the position of the pinion 825 so that it does not come off in the axial direction.

FIG. 12 shows the mold in an open state.

Now, when the rod 822 of the hydraulic cylinder 821 is pressurized to move forward, the rear platen 814 moves forward, and therefore the mold attached to the rear platen 814 moves forward.

At the same time that the above operation occurs, the rear platen rack 823 also moves forward, causing the pinion to rotate clockwise and causing the connected platen rack 824 to retreat.

Since the connecting platen rack 824 is connected to the front platen 813 via the connecting platen 815 and the tie bar 816, the front platen 813 is retracted, and therefore the mold attached to the front platen 813 is retracted.

Through the process described above, both molds 812 are closed while maintaining their relative center positions at a constant position.

Reference numeral 83 is a mold recess corresponding to the bottle neck, but when the mold closing is completed by the above-mentioned operation, the two molds 81
1 form a circular hole by joining together.

9 is a mandrel driving device, and the mandrel 91 is driven into the bottle neck by the operation of the mandrel preparation air cylinder 92, and the inner diameter of the bottle neck is finished with high precision, and the resin pressurized by the mandrel 91 is The water flows deep into the engraved part of the bottle neck 83 and can finish the bottle neck of the molded product with high precision.

Having described the apparatus of the embodiment of the present invention above, the operating sequence thereof will now be described.

First, the plasticized resin in the screw extruder is transferred to the die 3.
It is extruded and becomes a parison.

The parison is continuously extruded at a speed depending on the feed capacity of the screw extruder.

During this time, the extension mandrel 32, the bottom forming device 4, and the cutting device 5 move in the direction of progress of the parison in synchronization with the extrusion speed of the parison.

In the movement operation, the reciprocating section is moved by a variable speed motor 1470 with a speed reducer, and the speed of movement is synchronized by adjusting the rotation speed of the motor 1470.

The parison is then held by a parison holding device 6.

The holding operation is performed by advancing the chuck 65 that holds the parison, which was located behind the parison, to the center position of the parison, closing it, and applying vacuum.

When the above holding operation is completed, the parison is cut at the same time as the holding operation is completed or after a slight time delay.

The cutting operation is performed by moving the reciprocating section 52 forward or backward to cause the cutting blade 524 to traverse the parison.

Once the above cutting operation is completed, the bottom of the parison is formed either simultaneously with the completion or with a slight delay.

The parison forming operation is performed by activating the torque actuator 424 to advance a tool 433 for pressing the parison and a tool 432 for sealing the parison toward the axis of the parison to seal the cut open bottom surface.

In molding the parison, the extension mandrel 32 and the aforementioned tools 433 and 432 that come into direct contact with the parison can be cooled with water or air to facilitate mold release.

In order to further promote mold release, it is desirable to operate a mushroom valve 321 provided at the tip of the extended mandrel to protrude the valve portion and blow out air.

When the release of the parison bottom and the tip of the extension mandrel is completed, the extension mandrel 32, bottom forming device 4 and cutting device 5 are moved in the direction opposite to the direction in which the parison advances, either at the same time as the release is completed or with a slight delay. and move it.

During this time, the bottom forming device 4 is operated by a torque actuator 424.
is operated in the opposite direction to the above-mentioned operating direction, and the tool 433 for suppressing the parison and the tool 432 for sealing the parison are moved back and placed.

On the other hand, the extension mandrel 32, the bottom forming device 4, and the cutting device 5
When the reciprocating portion consisting of the above continues to move in the direction of movement of the parison in synchronization with the movement speed of the parison, the stopper 44 provided on the lower surface of the bottom forming device 4 finally stops the support plate 612 of the parison holding device 6. It comes into contact with the upper surface 66.

Although it is necessary to perform the parison holding operation and the subsequent cutting operation as soon as possible after the above-mentioned contact, it is preferable to carry out the carriage operation immediately after the parison cutting is completed.

Since the reciprocating portion described above is moving in the direction of movement of the parison in synchronization with the moving speed of the parison, at the same time the stopper 44 comes into contact with the upper surface 66 of the support plate, the parison holding device also moves to the reciprocating portion. Pushed by and synchronously, they begin to move.

At this time, the halinon holding device 6 is configured to move in the same direction as the movement direction of the parison at the time of starting.

That is, the parinon holding device 60 base plate 61 is fixed to the follower 711 of the carriage device main body,
The follower 111 moves along the shape of the contact surface of the cam plate 124 via the wheels, and the locus of movement of the follower 111 is in the direction of cutting in the direction of movement of the parison at the time of starting.

Although it is necessary to cut the parison while the above-mentioned parison holding device is being pushed by the reciprocating part and moving in sync, it is preferable to move the parison holding device as quickly as possible after cutting is completed. .

That is, it is necessary to prevent the cut lower surface of the parison, which is continuously descending, from coming into contact with the upper surface of the separated parison again.

During the period after the reciprocating portion contacts the Parinon holding device and until the carriage device 1 operates, the hydraulic cylinder 72 is not pressurized in either the front or rear direction, and the reciprocating portion does not touch the Parinon holding device. When pressed, the parison holding device connected to the hydraulic cylinder with the rod 722 follows without resistance, but after the parison is cut, the hydraulic cylinder 72 of the carriage device 7 is activated and the parison holding device is moved toward the mold by the carriage mechanism.

Once the parison is conveyed between the two molds 810, the hydraulic cylinder 821 of the mold clamping mechanism 82 is activated, and the rear platen 814 moves forward, at the same time the movement is carried out by the rear platen rack 823, pinion 825, and connecting platen rack 82.
4. It is transmitted to the front platen 813 via the connecting platen 815 and the tie bar 816, and the front platen 813 moves toward the parison in synchronization with the rear platen 814, and finally the mold 81 is closed.

Once the mold 81 is closed, air is supplied to the inside of the chuck 65 of the parison holding device 6, the vacuum pressure is released, and the air cylinder 613 is operated to open the chuck.

The mandrel 91 of the driving device 9 is driven into the parison while the upper end thereof is held by the mold neck 83, and the neck is calibrated.

Air is then blown through the interior of the mandrel, which causes the parison to expand and conform to the mold cavity.

Since the inside of the mold 811 is cooled, the expanded molded product described above is cooled and solidified.

Then, operate the hydraulic cylinder in the opposite direction to the above-mentioned direction,
The mold is opened and air is blown through the mandrel to cause the molded product to fall.

The above is the molding cycle, and the operations are repeated in the above order.

In the above explanation, the cut parison is held by the parison holding device and transported to the position of the mold clamping device by the carriage device, but the mold itself installed in the mold clamping device sandwiches and holds the parison, and the mold clamping device itself Similarly, it may be carried to the same mold clamping device position as described above using a carriage device.

However, in this case, it is necessary to move the heavy mold clamping device at high speed, which requires more energy.
It is also necessary to pay attention to shock absorption when stopping.

Furthermore, in the above-mentioned embodiments, the reciprocating motion of the reciprocating assembly such as the extension mandrel, bottom forming device, cutting device, etc. is achieved by rotating a screw with a variable speed motor, and the vertical motion is switched by a mechanical mechanism using a forward/reverse rotation switching clutch. explained.

Regarding the reciprocating motion, there are mechanical methods such as a method using a rack and pinion instead of a screw, and a method using a cam, and there is no problem even if these methods are used.

A method using hydraulic pressure or pneumatic pressure may also be considered.

In particular, if a hydraulic cylinder is provided on the top plate 123 of the bracket and the rod is connected to a reciprocating assembly to programmatically control the movement of the rod, it is possible to have more desirable position and speed control than simply switching between forward and reverse directions of uniform motion. It has the advantage that it can be easily carried out, and its condition settings can be freely adjusted.

As described above, according to the present invention, generation of a large amount of scrap, which has been a disadvantage of conventional extrusion blow molding, can be minimized.

By reducing scrap generation, productivity increases and the effort of scrap collection can be saved.

Note that the effect of reducing the amount of scrap generated is particularly remarkable in multilayer flow molding.

Conventionally, multilayer flow molding generates scrap that is a mixture of multiple materials, making it difficult to recycle it as is.

However, according to the present invention, the only scrap generated is trimming loss at the neck, so the scrap generation rate is reduced to 1% of the product.
It can be stopped within 0%.

This is a significant improvement compared to the 30% or more scrap generated in the past.

In addition, traces of bottom pinch-off, which are a drawback of conventional extrusion blow molding, can be eliminated.

The pinch-off traces were not only visually unsightly (they also led to a decrease in strength).

According to the present invention, since the bottom portion is formed in advance using a pine mold type bottom forming device, a beautiful finish can be achieved.

Furthermore, the effect of eliminating pinch-off is particularly significant in multilayer blow molding.

Conventionally, in multilayer blow molding, it has been difficult to form each layer into a continuous layer of uniform thickness at the pinch-off portion, and layer breakage has often occurred.

If the adhesive layer were to break, the adhesive strength would be reduced, leading to breakage, especially when dropped.

Furthermore, if the gas or water vapor barrier layer were to break, the barrier performance against gas and water vapor permeation would inevitably deteriorate.

On the other hand, in the case of the present invention, since there is no pinch-off portion cut into a straight line, all of the above-mentioned drawbacks can be avoided.

Furthermore, the present invention is basically extrusion blow molding, which has a much simpler structure and requires less initial investment than injection blow molding.

Furthermore, unlike injection blow molding, it is not necessary to use a plurality of molds, so there is an advantage that investment in molds can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of an embodiment of the present invention, and FIG. 2 is a perspective view of another embodiment of the invention. FIG. 3 is a partially cutaway front view of the vicinity of the die and the reciprocating assembly, and FIG. 4 is a partially cutaway side sectional view of the vicinity of the die and the reciprocating assembly. 5 is a sectional view taken along the line AA in FIG. 4, FIG. 6 is a longitudinal sectional view of the mandrel, and FIG. 7 is a sectional view taken along the line BB in FIG. 4. FIG. 8 is a partially cutaway side view of the cutting device shown in FIG. 7. 9 and 10 are a plan view and a partially cutaway side view of the parison holding device. Further, FIG. 11 is a longitudinal cross-sectional view of the engagement device portion of the parison holding device. FIGS. 12 and 13 are a partially cutaway plan view of the parison carriage device and the mold clamping device, and a front view showing only the main parts. In the figure, 1 is the molding machine frame, 21, 22 is the screw extruder, 3 is the die, 4 is the bottom forming device, 5 is the cutting device, 6 is the parinon holding device, 7 is the carriage device, 8 is the mold clamping device, and 9 is the molding device. It is a driving device. Further, 524 is a tool for cutting the parison, that is, a cutting blade, 31 is a mandrel, 32 is an extension mandrel, and 43
2 is a tool for sealing the parison; 65 is a tool for holding the parison; 81 is a mold; 83
is the mold neck. 38 indicates a parison.

Claims (1)

[Claims] 1 A synthetic resin melt is extruded into a cylindrical shape by a die to form a parison, the parison is cut with a cutting blade, and a liquid is blown into the parison while the cut parison is held in a mold. A molding device that molds a hollow body by a pressing operation includes a device that holds the parison from the outside at a position extending from the die exit in the extrusion direction, and a device that cuts the parison at a position closer to the die than the position of this holding device. , a device for sealing the cut end face of the parison on the side connected to the die to form a bottom, and the parison holding device together with the parison cutting device at least in the direction of movement of the parison during the cutting period of the parison. A hollow body forming device characterized in that it moves at approximately the same speed and in the same direction. 2 The sealing device moves the tool from the outside of the parison toward the center so that the parison is butted, and the sealing device cuts into the space created between the extended tip of the mandrel and the butting tool in the butted state. 2. The apparatus for forming a hollow body according to claim 1, wherein the bottom of the parison is formed by filling the material at the end of the parison. 3. The hollow body according to claim 1, wherein the sealing device is also adapted to move at substantially the same speed and in the same direction as the parison is moving, at least during the period of forming the bottom of the parison. molding equipment. 4. After cutting the parison, the carriage direction of the parison holding device is substantially the same as the moving direction of the parison, and the moving speed is equal to or higher than the moving speed of the parison at the initial stage of the movement. The apparatus for forming a hollow body according to item 1. 5. The apparatus for extruding the synthetic resin melt is configured to use a plurality of extruders to feed a plurality of plasticized resin dies to extrude a multilayer parinone. Hollow body forming equipment.