JPH0332451B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a nozzle device for an injection molding machine, and more particularly to a nozzle device for an injection molding machine that makes it possible to improve the positioning accuracy of a nozzle hole and a poppet for opening and closing the nozzle hole. It is something.

In an injection molding machine, during mold clamping and injection after closing the mold, pressurized molten resin is injected into the mold through the nozzle hole by a plunger or screw, while when opening the mold after holding pressure, the nozzle A nozzle device is required to close the hole and prevent leakage of the molten resin, and the nozzle device having the above function is attached to the tip of the heating cylinder.

FIGS. 1 and 2 show the configuration of a nozzle device that has been used in such injection molding machines for some time.

In the figure, inside the heating cylinder 1 is a plunger 2.
is inserted so as to be able to move forward and backward, and a nozzle device 3 is fixed to the tip of the heating cylinder 1 through an upper mold plate (not shown). This nozzle device 3 consists of a nozzle adapter 4 fixed to the tip of a heating cylinder 1, and a nozzle body 5 screwed to the tip of the nozzle adapter 4. The nozzle adapter 4 has a pair of resin passages 6, A poppet holding hole 7 and a spring retainer through hole 8 are bored. The resin passage 6 communicates the plasticizing chamber 9 defined by the heating cylinder 1 and the plunger 2 with the annular space 10 defined by the nozzle adapter 4 and the nozzle body 5. is nozzle adapter 4
The poppet 11 is housed so as to be slidable in the axial direction. This poppet 11
has a shaft portion 13 which has a smaller diameter than the poppet holding hole 7 and forms a required amount of clearance 12 with the nozzle adapter 4, and a shaft portion 13 which protrudes into the annular space 10 and has a tip seat surface 14 and a step seat surface. The stepped seat surface 15 can close the clearance 12 by coming into contact with and separating from the tip of the nozzle adapter 4. The spring retainer through hole 8 intersects with the poppet holding hole 7 and extends in a direction perpendicular to the plane of the paper in FIG.
A spring retainer 17 is inserted into the through hole 8 so that the nozzle adapter 4 can move freely in the axial direction. Spring retainer 17 and nozzle adapter 4
Since a spring 18 is compressed between the spring 18 and the base, the spring retainer 17 is always biased toward the tip of the nozzle adapter 4, comes into contact with the rear end of the shaft 13 of the poppet 11, and presses it down. ing.

On the other hand, the nozzle body 5 has a nozzle hole 19 bored on its axis, and the nozzle hole 19 connects the annular space 10 and the resin introduction passage 20 of the upper mold that is fastened to the upper mold plate. It is opened and closed by the seat surface 14 of the distal end of the poppet 11. The nozzle body 5 has an annular step 5a that can be engaged with a step 4a formed at the tip of the nozzle adapter 4, and these steps 4a, 5a constitute a spigot mechanism 21 for positioning. are doing.

In the above conventional configuration, the poppet holding hole 7 and the nozzle hole 19 are separately formed in two independent members, that is, the nozzle adapter 4 and the nozzle body 5, and when assembling the poppet holding hole 7 and the nozzle hole 19, After fixing the nozzle adapter 4 to the tip of the heating cylinder 1, the poppet 11 is inserted into the poppet holding hole 7, and the poppet 11 is brought into contact with the spring retainer 17. After that, while being positioned by the spigot mechanism 21, the nozzle is inserted. The nozzle body 5 was screwed onto the adapter 4.

In order for the tip sheet surface 14 to reliably close the nozzle hole 19, it is necessary to align the axis of the poppet 11 with that of the nozzle hole 19. , the nozzle body 5 was positioned and screwed onto the nozzle adapter 4 by the spigot mechanism 21.
However, with the positioning using the spigot mechanism 21, it is difficult to accurately align the axis of the poppet 11 with that of the nozzle hole 19.
After assembly, even if the poppet 11 is not aligned on the axis of the nozzle hole 19, the poppet holding hole 7 is set in advance so that when the poppet 11 is pressed against the nozzle body 5, it can approach the nozzle hole 19 while exploring it.
It was necessary to drill a large diameter hole to define a large clearance 12 between the poppet 11 and the nozzle adapter 4.

By the way, in the conventional nozzle device 3, during the mold closing and mold clamping process, the poppet 11 is urged by the elastic force of the spring 18 and comes into contact with the nozzle body 5 to close the nozzle hole 19, but during the injection process When the pressurized molten resin is forced into the annular space 10 through the resin passage 6 as the plunger 2 moves forward, the poppet 11 is separated from the nozzle body 5 against the elastic force of the spring 18. , nozzle hole 1
Open 9. As a result, the molten resin flows into the die-carving space through the resin introduction passage 20 of the mold while being pushed by the plunger 2. During this time,
The pressure of the molten resin is high, but since the step sheet surface 15 closes the gap 12, the molten resin closes the gap 12.
It will not go inside. However, when the plunger 2 retreats after the pressure holding process is completed and the pressure of the molten resin in the annular space 10 decreases, the poppet 11 is again urged by the elastic force of the spring 18 and descends, making contact with the tip of the nozzle adapter 4. come into contact with

At this time, the large clearance 12 formed based on the above-mentioned necessity communicates with the annular space 10, and the molten resin actively enters into the clearance 12.
As a result, the molten resin gradually accumulates in the clearance 12, resulting in malfunction of the poppet 11 and furthermore, the molten resin overflows from the spring retainer through hole 8.

An object of the present invention is to form a poppet holding hole in a nozzle body so as to be integral with the nozzle hole and have a common axis, in view of problems such as malfunction of the poppet based on the above-mentioned conventional technology. By this,
An excellent injection molding machine that allows the poppet to be accurately aligned on the axis of the nozzle hole, thereby reducing play within the poppet holding hole and preventing poppet malfunction and molten resin from spilling out. The present invention aims to provide a nozzle device.

In accordance with the above object, the present invention has a structure in which a nozzle body is connected to a nozzle adapter fixed to the tip of a heating cylinder, a nozzle hole is bored at the tip of the nozzle body, and the melt is poured into the mold from there. The resin is injected, and a poppet holding hole extending along a common axis with the nozzle hole is formed integrally with the nozzle hole inside the nozzle body. A poppet having an axis line of The gist of the present invention is to maintain the poppet at a high height, eliminate play between the outer periphery of the poppet and the inner periphery of the poppet holding hole, and thereby enable the poppet to be inserted tightly into the poppet holding hole.

The structure and operation of the embodiment of this invention are shown in FIGS. 3 to 6.
The explanation will be as follows based on the figures.

Each figure shows a nozzle device of an injection molding machine according to an embodiment of the present invention.The base end of a nozzle adapter 26 is fixed to the tip of the heating cylinder 25, and inside the nozzle adapter 26, Heating cylinder 25
and a plasticizing chamber 28 defined by the plunger 27
A pair of first resin passages 29 are formed to communicate with the tip of the nozzle adapter 26. Furthermore, a storage hole 30 extending in the axial direction is bored in the center of the nozzle adapter 26.
0 opens on the side surface of the nozzle adapter 26 and intersects with a through hole 32 through which the spring retainer 31 loosely passes. The lower end of the through hole 32 is provided with an annular poppet regulating step 26a. Storage hole 30
The central shaft portion of the nozzle body 33 is inserted into the nozzle body 33, and inside the nozzle body 33, there is a poppet holding hole 34 extending along the axis within the central shaft portion, leaving a sleeve at the peripheral edge. A nozzle hole 35 having a common axis and opening at the tip, and a first resin passage 2
A pair of second resin passages 36 are bored through which the poppet 9 communicates with the nozzle hole 35 via the tip of the poppet holding hole 34. A poppet 37 having a common axis is housed in the poppet holding hole 34 so as to be slidable in the axial direction. Poppet 37 is
A shaft portion 37a that passes through the poppet holding hole 34, a head portion 37b formed on the tip seat surface 38 that abuts and separates from the nozzle hole 35, and a head portion 37b that freely passes through the center of the step portion 26a and abuts the spring retainer 31. The end face of the shaft portion 37a from which the abutment rod 37c projects is formed on a step sheet surface 39 that engages with the step portion 26a. and,
When processing the nozzle body 33, the nozzle hole 3
5 and poppet holding hole 34 can be performed simultaneously and integrally, both can be drilled with good centering accuracy.

Although the poppet holding hole 34 has a slightly larger diameter than the shaft 37a in order to facilitate sliding of the shaft 37a, it does not have a clearance 12 equivalent to the conventional nozzle device 3. To add, in the embodiment, both the first resin passage 29 and the second resin passage 36 are composed of a pair of paths, so
90° from the first and second resin passages 29 and 36, respectively
Relative rotation between the nozzle adapter 26 and the nozzle body 33 is prevented by installing locking pins 40 for positioning at separate positions.

The nozzle body 33 is formed with a stepped portion 33a for locking a coupling ring 41 as coupling means, and an internal thread 41a screwed onto the coupling ring 41.
is screwed onto the tip of the nozzle adapter 26 and can be screwed onto the external thread 26b.

A coil spring 42 is provided between the spring retainer 31 and the base end of the nozzle adapter 26.
The spring 42 constantly urges the spring retainer 31 in the direction of the distal end of the nozzle adapter 26 to bring the spring retainer 31 into contact with the contact rod 37c. The nozzle device having such a configuration passes through an upper mold plate (not shown), and an upper mold 44 attached to the lower surface of the upper mold plate.
It is connected to the resin introduction passage 45 of.

In the above configuration, during injection molding work,
After the mold is closed and clamped, when the plunger 27 is moved forward, the pressure of the molten resin in the plasticizing chamber 28 is increased, and the first,
The second resin passages 29, 36 are further connected to the head 37b of the poppet 37 through the tip of the poppet holding hole 34.
As shown in FIG. 6, the poppet 37 slides upward against the urging force from the spring 42 until the step sheet surface 39 abuts the step 26a, opening the nozzle hole 35. develop. After the nozzle hole 35 is opened, when the plunger 27 continues to move forward, the molten resin in the plasticizing chamber 28 flows through the nozzle hole 35.
The resin flows into the resin introduction passage 45 of the upper mold 44 and reaches the mold engraving space. When the pressure of the molten resin is increased, the molten resin tries to flow into the poppet holding hole 34, but since no clearance is defined between the holding hole 34 and the poppet 37, the resin does not flow into the holding hole 34. There isn't.

Even if the molten resin gradually enters the poppet holding hole 34 during long-term use, the molten resin will be blocked by the contact between the step sheet 39 and the step 26a, so that the molten resin will not penetrate. It does not overflow from the hole 32.

Subsequently, after a predetermined pressure holding step, when the plunger 27 retreats, the pressure of the molten resin decreases, and as a result, the poppet 37 responds to the biasing force of the spring 42, as shown in FIGS. 3 to 5. Since the tip sheet surface 38 closes the nozzle hole 35, the mold can be opened. At this time, since the centering accuracy of the poppet 37 and the nozzle hole 35 is sufficiently ensured, the tip sheet surface 38 moves straight down and closes the nozzle hole 35 without searching for the nozzle hole 35. .

As described above, according to the present invention, the nozzle body 3
By drilling the poppet holding hole 34 in the central axis of the nozzle body 33 with the peripheral edge remaining as a sleeve, the nozzle hole 35 and the poppet holding hole 34 coaxial therewith can be integrated into the nozzle body 33. By adopting the configuration in which the nozzle hole 35 and the poppet holding hole 34 are drilled, the centering accuracy of the nozzle hole 35 and the poppet holding hole 34 can be significantly improved, and the poppet holding hole 34 and the poppet holding hole 34, which were required in the conventional nozzle mechanism, can be improved significantly. Since the gap between the poppets 35 loosely inserted into the poppet 35 can be greatly reduced to allow both members to slide closely together, malfunction of the poppets due to resin accumulation in the gap and leakage through the gap can be avoided. It has the excellent effect of completely preventing resin overflow.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing the nozzle structure of a conventional injection molding machine, Fig. 2 is a sectional view taken along the line A-A in Fig. 1, and Figs. 3 to 6 show examples of this invention. There is a
FIG. 6 is a sectional view taken at a different angle, and is a sectional view at the same position as FIG. 3 during the injection process. 25... Heating cylinder, 26... Nozzle adapter, 2
9...First resin passage, 30...Storage hole, 33...
Nozzle body, 34... poppet holding hole, 35... nozzle hole, 36... second resin passage, 37... poppet, 41... coupling means (coupling ring), 44...
Mold (upper mold), 45...Resin introduction passage.

Claims (1)

[Scope of Claims] 1 The base end is fixed to the tip of the heating cylinder 25, a first resin passage 29 is bored inside through which the molten resin from the heating cylinder 25 passes, and a first resin passage 29 is provided in the center extending in the axial direction. The nozzle adapter 26 has a storage hole 30 formed therein, and the central shaft portion is inserted into the storage hole 30.
connected to the tip of the nozzle adapter 26, and the first
The nozzle body 33 intermittently injects the molten resin from the resin passage 29 into the resin passage 45 of the mold 44, and the nozzle body 33 has a nozzle hole aligned with the resin passage 45 of the mold 44 at the tip. 35 is bored inside the nozzle body 33, a poppet holding hole 34 is bored in the central shaft portion along the same axis as the nozzle hole 35, leaving a sleeve at the peripheral edge, and A second resin passage 36 is bored through which the resin passage 29 and the nozzle hole 35 communicate with each other via the tip of the poppet holding hole 34 . A poppet 37 having an axis has its tip aligned with the nozzle hole 3.
5. A nozzle device for an injection molding machine, wherein the nozzle device is biased toward the distal end thereof and slidably inserted in the axial direction so as to be able to come into contact with and separate from the nozzle device.