JP2910793B2 - Pinch method and pinch device on parison - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to a blow molding machine, and a method and an apparatus for pinching a parison pinched in a mold before pre-expanding a lower end of the parison when the hollow parison is injected from an injection die. Regarding improvement.

[0002]

2. Description of the Related Art In a blow molding machine, a molten resin supplied from an extruder is formed into a cylindrical molten resin cylinder called a parison by a die having a ring-shaped resin discharge port, and this is molded by a mold. After being sandwiched, a gas such as air is blown into the parison to cool it, thereby forming a hollow product.
Prior to being sandwiched by the mold, the lower end of the parison is sealed by a pinch device, and gas is blown into the parison through a blow nozzle attached to the mold or the pinch device to expand the parison.

Conventionally, a pinch device for sealing a parison has a pair of pinch arms 2 extending immediately below a die 1 as shown in FIGS. A parison 3 ejected from the die 1 is sandwiched and sealed by opening and closing the tip of the parison 3 by being opened and closed by a built-in opening / closing mechanism such as a link mechanism provided on the side. The opening / closing mechanism built-in portion of the parison pinch device is connected to a traveling member 5 attached to a traveling rail 4 so that a molded product can be carried out in a pinched state.

[0004] A parison pinch operation using such a conventional device is performed as follows. That is, in the parison injection die 1, the parison 3 is injected with a low injection speed, and after the start of injection, the parison 3 is pinched by the pinch arm 2 by lowering or stopping the parison speed in order to seal the tip of the parison 3. After the pinch is completed, the pinch arm 2 is opened, the parison 3 is injected at a predetermined speed, and the injection is completed. After the injection is completed, the mold is clamped, and a gas is blown to mold and cool. During this time, the pinch arm 2 is closed to hold the upper end of the parison 3. After the cooling is completed, the mold is opened, the pinch device holding the parison 3 is moved by the traveling member 5, the product is taken out, and the pinch arm 2 is opened at a predetermined position to drop the product. After that, it is returned to the original position and made to stand by.

[0005]

However, according to the above-described conventional method, the injection speed is reduced or stopped when the tip of the parison is pinched (so-called upper pinch) and sealed after the start of the injection. There is a problem that it takes time until the injection is completed, and the parison draws down or is solidified by cooling, making molding difficult. For this reason, when an engineering plastic which easily draws down and has a high solidification rate is used as a molding material, the problem becomes even more problematic. In addition, since the conventional parison pinch device also serves as a pinch for taking out the product, the end to be the next parison is partially ejected from the injection die during the unloading operation, thereby separating the parison from the die. Therefore, the parison part between the die and the mold does not become a product,
There is also a problem that a large amount of material is lost and the yield is reduced.

An object of the present invention is to focus on the above-mentioned conventional problems, and it is not necessary to reduce or stop the injection speed during injection during a parison pinch, so that a method and apparatus for pinching on a parison that enables high-speed injection. Second, the present invention provides a method and apparatus for pinching a parison on a parison, in which when a parison continuously injected is pinched and cut, a previously injected portion is effectively used to improve the yield. It is the purpose.

[0007]

In order to achieve the above-mentioned object, a parison injection method according to the present invention comprises a method for pre-expanding a lower end of a hollow parison which is injected and suspended from an injection die toward a position sandwiched by a mold. In the method of pinching the parison above, the lower end of the next injection parison is sealed after the shot is completed at a position immediately below the injection die. In this case, the lower end of the next injection parison is sealed, and the periphery of the sealed next injection parison can be heated and held.

[0008] Further, the parison pinch device according to the present invention,
An upper and lower dual parison pinch mechanism is placed between the injection die and the mold located below it, a parison heating heater is attached to the upper pinch mechanism, and the lower pinch mechanism is connected to the product take-out traveling frame. Thus, it is possible to enter and exit the lower part of the injection die.

[0009]

According to the above construction, a pair of upper and lower parison pinch mechanisms are operated at the time of completion of each shot for successively injecting parisons, and the upper pinch mechanism seals the lower end of the succeeding parison. Can take out the product by the lower pinch mechanism, and at this time, the injection from the die can be performed in parallel. Therefore, the parison injection can be performed without waiting for the completion of the product discharge, and the injection cycle time can be shortened. In addition, since the lower end of the parison of the next shot is sealed in the previous shot, the sealing work is performed using the time lag between shots, so it is not necessary to lower or stop the injection speed midway, and high-speed injection is possible Becomes

[0010] Further, the parison lower end is sealed prior to the subsequent shot, and the parison end protruding from the lower surface of the injection die is heated by a heater provided along with the upper pinch mechanism. It is suppressed and the part can be used without wasting, and the yield can be improved.

[0011]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a parison pinch method and apparatus according to the present invention.

FIG. 1 to FIG. 3 are configuration diagrams of a parison pinch device according to an embodiment. As shown in these figures, the parison pinch device 10 is disposed above a mold 12 installed below and directly below a parison injection die 14 so as to pinch a parison 16 which is injected and suspended. It is configured. The parison pinch device 10 includes an upper pinch mechanism 1 vertically arranged along a parison hanging direction.
8 and a lower pinch mechanism 20.

First, as shown in FIG. 2, the upper pinch mechanism 18 has a fixed frame 24 formed in a rectangular shape so as to surround the resin discharge port 22 of the die 14, and is parallel to the inside of the fixed frame 24. A pair of pinch blades 26, 26 which are passed over are attached. Each of the pinch blades 26 is supported so that both ends thereof can be traversed by the fixed frame 24. By moving the pinch blades 26 closer to each other, the pinch blades 26 are joined at the center of the frame to pinch the parison 16 penetrating through the center of the fixed frame 24. I can do it. In order to open and close the pair of pinch blades 26, 26, a housing box 28 of a driving mechanism is provided at one end of the fixed frame 24.
And a hydraulic cylinder 30 is built in the box 28. The direction of expansion and contraction of the hydraulic cylinder 30 is orthogonal to the traversing direction of the pinch blade 26. To this end, an open leg link 32 is connected and connected to one end of both pinch blades 26 protruding into the box 28. I have. Thus, the pair of pinch blades 26 can be brought closer to each other or moved away from each other by moving the hydraulic cylinder 30 in and out.

A heater 34 is mounted on the inner peripheral surface of the fixed frame 24. The heater 34 heats the subsequent parison 16R which is sandwiched between the pinch blades 26 and 26 and partially ejected from the resin discharge port 22. I am trying to do it.

A lower pinch mechanism 20 having a structure similar to that of the related art is arranged at a position below the upper pinch mechanism 18 described above. That is, it has a pair of pinch arms 36, 36 extending from the side of the die 14 to a position directly below the upper pinch mechanism 18. The pinch arms 36, 36 are capable of pinching or separating the parison 16 by opening and closing legs immediately below the upper pinch mechanism 18, and support the base end of each arm 36 on a support box 38. As shown in FIG. 3, a rotation shaft 40 is provided at an end of each arm 36 in the support box 38, and a leg link 42 is connected to the rotation shaft 40. The drive mechanism which connected the rod is built in. For this reason, the pair of rotating shafts 40 are rotated by expanding and contracting the driving cylinder 44, and the pinch arm 3 is rotated.
6 can be given an open leg operation or a closed leg operation.
By opening and closing the tips of the pair of pinch arms 36, 36, the parison 16 ejected from the die 14 is held under the upper pinch mechanism 18. Further, the parison pinch device 20 has a support box 3
8 is connected to a traveling member 48 mounted on a traveling rail 46 provided on a gantry frame of the blow molding machine, so that the molded product can be carried out in a pinch state.

In the embodiment, one contact surface of the pinch blades 26, 26 in the upper parison pinch mechanism 18 is shown in FIG.
A parison cutter 50 is formed as shown in FIG.
6 is separated and cut. As shown in FIG. 2B, a fusing cutter 54 composed of a heater is provided at the lower edge of both pinch blades 26, 26 via a heat insulating material 52 to blow the parison 16 at the time of pinching. You may make it separate.

The parison pinch method using the parison pinch device thus constructed is as follows. Only when the first molding cycle is performed, first, the parison 16 is slightly injected, and the parison 16 is
Seal the lower end of. After this sealing, injection is performed to mold 1
The upper pinch mechanism 18 and the lower pinch mechanism 20 are driven to close the pinch blades 26, 26 and the pinch arms 36, 36 during the molding operation. Thus, the cutter 50 (54) provided on the pinch blade 26 of the upper pinch mechanism 18 seals the lower end of the subsequent parison 16R and cuts and separates it from the preceding parison 16F. The preceding parison 16F is held by the lower pinch mechanism 20, and is blow-molded. After molding completed product a lower pin
While being held by the pinch mechanism 20 , it is carried out by the moving operation of the traveling member 48, the pinch arms 36, 36 are opened at predetermined positions, dropped into the product container, returned to the original position, and made to stand by. After the parison sealing is completed at the lower part of the die 14, the upper pinch mechanism 18 opens the pinch blades 26, 26 and waits for the next shot. At this time, the heater 3 provided on the inner peripheral surface of the fixed frame 24
4 heats a part of the subsequent parison 16R protruding from the resin discharge port of the die 14 to prevent it from solidifying.

In the next cycle, the lower end of the subsequent parison 16R is sealed, so that the parison 16R is ejected at a predetermined speed. After the injection is completed, the mold is closed and molded. After this, this operation is repeated to perform high-speed parison injection and molding,
Thereafter, this cycle is repeated.

Although the cooling prevention heater 34 of the subsequent parison 16R may be always on, the parison 16R
May be turned on only when is facing the heater 34.

As described above, according to the parison pinch method and apparatus according to the present embodiment, the injection speed from the parison injection die 14 is reduced only at the time of the first shot.
The injection can be performed at a high speed during the subsequent shots. Therefore, it is not necessary to lower or stop the injection speed in the middle of the injection of the parison 16, and even if an engineering plastic material which is easy to draw down and is easily solidified is used as a molding material, the injection can be performed by high-speed injection and high-speed mold clamping. be able to.

Further, after one shot, the portion remaining by the parison cutting is heated by the heater 34 attached to the upper pinch mechanism 18, and as shown in FIG. The parts that have been discarded as burrs can be used effectively.

Further, since the lower end is sealed beforehand when the parison 16 is injected, the lower end shape of the parison 16 becomes a straight and clean shape, the amount of burrs is reduced, and the yield can be improved. At the same time, even when the parison length is controlled, there is an advantage that the lower end of the parison 16 can be accurately detected.

In the above-described embodiment, an example is shown in which the cutters 50 and 54 are provided on the pinch blade 26 of the upper pinch mechanism 18, but this may be provided on the pinch arm 36 of the lower pinch mechanism 20. Vertical pinch mechanism 18,
20 may be provided independently at an intermediate position.

[0024]

As described above, according to the present invention,
After the shot is completed at the position directly below the injection die, the lower end of the next injection parison is sealed, and if necessary, the periphery of the next injection parison is heated and held. Thus, there is no need to lower or stop the injection speed, and when the parison continuously injected is pinch-cut, it is possible to effectively utilize the already-injected portion to improve the yield.

[Brief description of the drawings]

FIG. 1 is a side view of a parison pinch device according to an embodiment.

FIG. 2 is a plan view of an upper parison pinch mechanism of the apparatus.

FIG. 3 is a bottom view of a lower parison pinch mechanism of the apparatus.

FIG. 4 is a side view showing a configuration example of a parison cutter.

FIG. 5 is an explanatory diagram of a comparison between a parison-sealed state by the apparatus of the embodiment and a conventional example.

FIG. 6 is a side view of a conventional parison pinch device.

FIG. 7 is a bottom view of the same device.

[Explanation of symbols]

Reference Signs List 10 parison pinch device 12 mold 14 parison injection die 16 (16F, 16R) parison 18 upper parison pinch mechanism 20 lower parison pinch mechanism 22 resin discharge port 26
Pinch blade 34 Heater 36 Pinch arm 46 Travel rail 48 Travel member

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-64-11819 (JP, A) JP-A-54-119558 (JP, A) Fully open 1988-170121 (JP, U) Really open 1988 84329 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) B29C 49/00-49/80 B29B 11/10

Claims (2)

(57) [Claims] 1. A parison upper pinch method for sealing a lower end of a hollow parison which is injected and dropped from an injection die toward a position sandwiched by a mold before pre-expansion, at a time when a shot is completed at a position directly below the injection die. A method of pinching the parison on the upper side, wherein the lower end of the next injection parison is sealed. 2. An upper and lower parison pinch mechanism is disposed between an injection die and a mold disposed below the injection die. A parison heating heater is attached to the upper pinch mechanism, and the lower pinch mechanism is taken out of the product. A parison pinch device, wherein the parison pinch device is connected to a traveling frame for use so that it can enter and exit a lower portion of an injection die.