JPH10315274A - Hot runner apparatus for molding preform - Google Patents

Abstract

PROBLEM TO BE SOLVED: To separately form a nozzle side runner of a hot runner so that generation of a weld on a side face of a preform by a hot runner apparatus having a valve nozzle arrives at a nozzle port without receiving interference of a needle valve. SOLUTION: In the hot runner apparatus 2 in which a nozzle port having a valve nozzle is brought into contact with a cavity gate of a preform molding injection mold 1, a resin reservoir 19 is formed at an upper part from an end retracting position of a needle valve 9. A nozzle side runner 18 of a hot runner 8 is obliquely formed separately from a valve inserting passage 16 toward the reservoir 19. The reservoir 19 is commonly used for both injection of the resin and opening/closing the valve.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot runner device having a valve nozzle for forming a preform.

[0002]

A thin-walled container such as a PET bottle is formed by stretching and blowing an injection-molded preform in a blow mold. A hot runner is used for injection molding of this preform.However, a sprue at the bottom of the preform is shortened, and a needle valve is provided in the nozzle as a means for preventing resin from dripping from the nozzle. Some include a provided valve nozzle.

FIG. 4 shows an example of this, in which a hot runner device 2 is disposed below an injection mold 1 for preform molding, and a nozzle member 4 protruding from the center of the upper surface of a runner block 3. The tip is in contact with a cavity gate 5 opened at the center of the lower surface of the injection mold 1.

[0004] Inside the runner block 3, there is provided a hot runner 8 extending from the gate 7 of the bush 6 provided on the side surface to the tip of the nozzle member 4, and a vertical nozzle side runner extending from the center of the block into the nozzle member. 8a
In addition, a needle valve 9 for opening and closing the nozzle port is inserted through the lower side of the runner block 3 so as to be able to advance and retreat, leaving a flow passage around the needle valve 9. The needle valve 9 is connected to a piston 11 of a driving cylinder 10 by air or hydraulic pressure at the lower portion of the hot runner device, and the operation of the driving cylinder 10 moves the nozzle-side runner 8a forward and backward to open and close the nozzle port.

[0005] In the hot runner device 2 having such a conventional structure, the needle valve 9 retreats and the nozzle is opened when the molten resin is injected and filled, and when the pressure holding after the filling is completed, the nozzle advances and the nozzle is closed. When the nozzle is opened, the molten resin flows through the nozzle side runner 8a around the needle valve and reaches the nozzle port.
2 to form a bottomed preform 13.

By closing the nozzle port by the needle valve 9, the molten resin in the hot runner is prevented from dripping from the nozzle port during the next injection. 13
Is often formed on the side of the. This weld 14 is caused by the fact that the molten resin from the gate 7 is divided into right and left by the needle valve 9 and flows into the nozzle side runner 8a.

Further, the ordinary runner block 3 is heated by a band heater or the like in order to maintain the temperature of the molten resin, but the needle valve 9 is only inserted through the runner block 3 and has a base end. Because the part is exposed outside the block and connected to the piston 11,
Even if the needle valve 9 is heated in the block, the temperature of the needle valve 9 becomes lower than that of the block side due to heat radiation at the exposed portion and heat transfer to the piston side, so that the molten resin flowing through the nozzle side runner 8a , A difference occurs between the block side and the needle valve side.

At the inlet of the nozzle-side runner 8a formed around the needle valve 9, the leading edge generated by the needle valve 9 divided into right and left is on the opposite side (downstream side).
However, since the flow on the needle valve side (inside) precedes the flow on the block side (outside), the merging at the tip edge is occupied by the inner resin where the resin temperature is low, and the merging at the merging is complete. The fusion cannot be expected, and the cavity is injected and filled with the diameter reduced by the nozzle port. As a result, the weld 14 is formed as a vertical linear mark on the side surface of the preform 13.

When the preform 13 is released from the injection mold 1 in a state where the shape is maintained by the skin layer formed on the surface and stretch blown into a packaging container such as a bottle without reheating, the weld The portion 14 is thicker than the others. This is presumed to be because the resin temperature of the weld portion is lower than that of the other portions, and the uneven thickness also varies to some extent depending on the thickness of the material resin and the thickness of the preform 14, but the smaller the thickness, the more easily the influence is exerted. It becomes difficult to obtain a good product having a thickness distribution suitable for the bottle shape and application.

The present invention has been conceived in order to solve the above-mentioned problem of the weld, and an object of the present invention is to form a hot runner so that a molten resin reaches a nozzle port without interference of a needle valve. Accordingly, it is an object of the present invention to provide a new hot runner device for forming a preform, which does not generate a weld while having a valve nozzle.

[0011]

SUMMARY OF THE INVENTION According to the present invention, there is provided a runner block having a hot runner inside which communicates a side gate with an inside of a nozzle member protruding upward, and a runner block capable of moving forward and backward with respect to the runner block. A needle valve that is inserted and opens and closes a nozzle port by a tip, and a driving device connected to the needle valve and disposed below a runner block, wherein the nozzle port is a cavity gate of an injection mold for preform molding. In the hot runner device in contact with the above, a resin reservoir is formed above the retreat position of the tip of the needle valve, and a nozzle-side runner of the hot runner is formed to be inclined separately from the valve insertion passage toward the resin reservoir. The resin pool is used for both resin injection and valve opening and closing.

The resin reservoir is formed in a nozzle member having a diameter larger than that of the valve insertion passage. The nozzle member includes a nozzle body and a nozzle tip attached to a tip of the nozzle body. A resin reservoir is formed over the resin reservoir, and both the valve insertion passage and the nozzle-side runner extend to the resin reservoir. The nozzle-side runner is a valve insertion passage inside the runner block. Are formed in parallel with the resin reservoir inside the nozzle body.
It is also a thing.

Further, the runner block comprises a columnar body or a prismatic body arranged horizontally long, and has a gate at the side center and a nozzle side runner provided for each of a required number of nozzle members projecting upward. The main runner is provided at an eccentric position avoiding the needle valve inserted in the center, and the main runner is directed from the main runner to the resin pool for each nozzle member. Is branched.

In the above configuration, since the molten resin is injected through the resin reservoir above the retreat position of the tip of the needle valve, the needle valve does not interfere with the flow of the molten resin after opening the nozzle port. The molten resin from the nozzle-side runner is injected and filled into the cavity from the nozzle port through the resin reservoir as it is. As a result, the occurrence of the weld on the side of the preform due to the intervention of the needle valve is solved, and it is possible to stretch-blow a bottle or the like having a thickness distribution suitable for the shape or use.

Since the resin reservoir and the nozzle-side runner are formed in the nozzle body, the structure of the runner block is not significantly changed, and can be implemented without being limited by the number of nozzles. Also in comparison with the above, the difference is limited only to the formation of the resin pool and the inclined formation of the nozzle side runner, and the configuration as a hot runner device for the injection mold for preform molding is not different from the conventional one, so the existing It is also compatible with injection molds and can be immediately adopted into the injection mold in use to form weld-free preforms.

[0016]

1 to 3 show one embodiment of a hot runner device of the present invention having a number of nozzles.
The illustration of the injection mold side is omitted, and the same parts as those of the conventional structure are indicated by the same reference numerals.

The hot runner device 2 uses a horizontally long runner block 3 made of a columnar body, and has a large number of nozzle members 4, 4 projecting at regular intervals at the center of the upper surface thereof. Such a hot runner device 2 is disposed below the injection mold 1 for preform molding, similarly to the conventional structure shown in FIG.

A hot runner 8 is provided inside the runner block 3 to communicate the gate 7 of the bush 6 provided on the side surface with the inside of each of the nozzle members 4. Further, a valve insertion passage 16 of a needle valve 9 for opening and closing the nozzle port is provided vertically through the center of the block at each position of the nozzle members 4, 4, and the needle valve 9 is provided in the valve insertion passage 16 with a runner. The working clearance is inserted from the lower side of the block to the nozzle opening, leaving around the shaft.

At the eccentric position of the runner block 3 avoiding the needle valve 9, a main runner of the hot runner 8 is provided in the longitudinal direction. From the main runner, the nozzle-side runner 18 is connected to each nozzle member 4,
Branches are formed at every four positions.

The nozzle member 4 includes the runner block 3
The nozzle body 4a is screwed into a recess 17 formed in the center of the upper surface of the nozzle body, and the nozzle tip 4b is screwed into the tip of the main body. An open resin reservoir 19 is formed up to a position where the distal end of the needle valve 9 is retracted. The resin reservoir 19 has a larger diameter than the extended portion 16a of the valve insertion passage 16 extended to the lower end, and upper and lower portions are formed as conical inclined surfaces, and the nozzle side runner 18 extends to the lower surface. Has been extended.

In the nozzle side runner 18, the main runner position of the hot runner 8 is located at a position shifted laterally from the center of the block where the nozzle openings of the nozzle members 4 are located. Although it is formed vertically in parallel with the valve insertion passage 16, it is formed to extend obliquely toward the lower part of the resin reservoir 19 in the nozzle body 4a. The angle θ of the extending portion 18a has a certain difference depending on the setting position of the main runner in the runner block 3 and the distance to the resin reservoir 19, but the angle θ of the extending portion 18a differs from the extending portion 16a of the valve insertion passage 16 in the nozzle body 4a. An angle range of about 20 ° is preferable from the viewpoint of processing to achieve compatibility.

In the drawing, reference numeral 20 denotes a support plate provided on both sides and a center portion of the runner block 3, which is mounted and fixed on a base member 21 in which a pair of hydraulic cylinders 10 are provided. 22 is a joint member of the needle valve 9;
The needle valves 9 are connected to the piston side via the joint members 22 so as to move forward and backward simultaneously by the operation of the hydraulic cylinder 10. is there.

In the hot runner device 2 having the above configuration, the retreat position of the tip of the needle valve 9 is set at the lower end of the resin reservoir 19, and the nozzle side runner 1 is located above the retreat position of the tip.
The resin pool 19 can be used for both injection of the resin and opening and closing of the valve by opening the extension portion 18a of the resin 8, and injection of the molten resin is performed after the tip of the needle valve 9 retreats. Since the flow is carried out through 19, the needle valve 9 does not interfere with the flow of the molten resin, and the molten resin is injected and filled into the cavity from the nozzle port through the resin reservoir 19. For this reason, the needle valve 9
The occurrence of welds on the side of the preform due to the presence of elimination is eliminated.

The resin reservoir 19 is provided on the nozzle side runner 18.
The needle valve 9 is formed larger in diameter than the valve insertion passage 16 formed separately from the shaft, that is, larger in diameter than the shaft diameter of the needle valve 9. Since a flow margin is secured around the nozzle, the nozzle port can be smoothly closed.

Further, in the resin reservoir 19 having a larger diameter than the extending portion 16a of the valve insertion passage 16, even if the retraction stroke of the needle valve 9 is longer than before, the resin reservoir 1 has a larger diameter.
Due to the molten resin around the needle valve lube in 9,
Immediately the retreat is filled, so the needle valve 9
Pool from the nozzle opening due to negative pressure even when the nozzle is retracted at high speed 1
9 is prevented from entering the air.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional side view of an embodiment of a hot runner device for preform molding according to the present invention.

FIG. 2 is a front view of the same.

FIG. 3 is a vertical sectional view of a main part of the above.

FIG. 4 is a vertical sectional side view of a conventional hot runner device having a valve nozzle and a preform molding die.

[Explanation of symbols]

 Reference Signs List 1 injection mold 2 hot runner device 3 runner block 4 nozzle member 4a nozzle body 4b nozzle tip 7 gate 9 needle valve 13 preform 14 weld 16 valve insertion passage 16a extended portion 17 recess 18 nozzle side runner 18a extension 19 Resin pool

Claims (5)

[Claims] 1. A runner block having a hot runner therein for communicating a side gate with an inside of a nozzle member protruding upward, and a needle which is inserted into the runner block so as to be able to advance and retreat and opens and closes a nozzle opening by a tip. A hot runner device comprising a valve and a driving device connected to the needle valve and disposed below the runner block, wherein the nozzle port is in contact with a cavity gate of an injection mold for preform molding; A resin reservoir is formed above the retreat position of the tip of the valve, and the nozzle side runner of the hot runner is formed to be inclined separately from the valve insertion passage toward the resin reservoir, and the resin reservoir is used for both resin injection and valve opening / closing. A hot runner device for preform molding, which is commonly used for: 2. The preform molding hot runner device, wherein the resin reservoir has a diameter larger than that of the valve insertion passage and is formed in a nozzle member. 3. The nozzle member comprises a nozzle body and a nozzle tip attached to a tip of the nozzle body. A resin reservoir is formed between the nozzle tip and the nozzle body, and the valve insertion passage and the nozzle extend to the resin reservoir. 3. The hot runner device for preform molding according to claim 1, wherein both of the side runners are extended. 4. The nozzle-side runner is formed in the runner block in parallel with the valve insertion passage, and is formed to be inclined to the resin reservoir in the nozzle body. A hot runner device for forming a preform according to any one of the above. 5. A nozzle block comprising a columnar body or a prism body arranged horizontally long, a gate at a side center and a nozzle-side runner provided for each of a required number of nozzle members projecting upward. In the longitudinal direction, the main runner is provided at an eccentric position avoiding the needle valve inserted in the center, and a nozzle side runner is directed from the main runner toward the resin reservoir for each nozzle member. The hot runner device for preform molding according to any one of claims 1 to 4, wherein the device is branched.