JP3189262B2 - Multi-cavity mold device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multiple mold apparatus used for injection molding of a resin.

[0002]

2. Description of the Related Art For example, in injection molding of a thermoplastic resin, a plurality of products are molded by one mold apparatus. In this case, a plurality of product-shaped cavities are formed between the fixed mold and the movable mold that open and close with each other, and the resin is injected into each cavity by a runner from a sprue that is one resin injection port provided in the fixed mold. Distribute.

FIG. 3 shows an example of the arrangement of runners in a multi-cavity mold apparatus. The mold device has eight cavities, and the runner has two branches from the sprue 1.
A secondary runner 2, a secondary runner 3 that branches off from both ends of the primary runner 2, and tertiary runners 4a and 4b that branch off from both ends of the secondary runner 3, respectively.
These tertiary runners 4a and 4b communicate with the cavities 5a and 5b via a spear system or the like which is a heating hot tip system. From the sprue 1 to the cavity 5a,
The distance to 5b is equal for all cavities 5a, 5b. The tertiary runners 4a and 4b include a reverse tertiary runner 4a folded back toward the primary runner 2 and a forward tertiary runner 4b directed to the opposite side. The cross-sectional diameter of the directional tertiary runner 4a and the cross-sectional diameter of the forward tertiary runner 4b were equal.

By the way, in a multi-cavity mold apparatus,
When the resin is a thermoplastic resin having low viscosity such as ABS resin or polystyrene, the filling balance between the cavities 5a and 5b becomes a problem. However, in the conventional mold apparatus, the primary runner 2 and the secondary runners 3 and 3
When the next runners 4a and 4b are located on the same plane,
There is a tendency that overfilling occurs in the cavity 5a located further inside, and underfilling occurs in the cavity 5b located further outside. As a result, the molded product may have dimensional differences. This is particularly problematic for thin-walled products such as the outer case of a video cassette.

[0005] As means for eliminating the imbalance in the filling between the cavities 5a and 5b, there is a method for eliminating the
The temperature of the body of the spear system may be changed every 5a, 5b. As a result of the trial, for example, the inner cavity 5a
When the temperature was set at 250 to 270 ° C., it was found that the filling balance could be maintained by setting the temperature of the outer cavity 5b to be higher by 40 to 50 ° C. But the cavity
If the temperature control is changed for each of 5a and 5b, this temperature control becomes troublesome.

As another means for eliminating the imbalance in filling, there is a method of increasing the temperature of the resin itself to enhance the fluidity of the resin. For example, if the temperature of the body is 300 to 3
If the temperature is set to 40 ° C., the filling balance can be considerably maintained without changing the temperature setting between the inner cavity 5a and the outer cavity 5b. However, increasing the resin temperature itself has many disadvantages.

On the other hand, depending on the arrangement of the runners,
Balancing the filling is also conventionally performed. Actually, as shown in FIG. 4, it has been conventionally provided between the primary runner 2 and the secondary runner 3 to have a vertical portion 6 perpendicular to both of them. Such a vertical part 6
Is provided, the filling balance can be obtained in each of the cavities 5a and 5b. However, when the vertical portion 6 is provided on the runner, the size of the mold device is increased.

[0008]

As described above, the secondary runner bends from the tip of the primary runner, and is folded back from the tip of the secondary runner toward the primary runner. In the conventional multi-cavity die apparatus in which the forward tertiary runner branches to the side, the cross-sectional area of the reverse tertiary runner is equal to the cross-sectional area of the forward tertiary runner. Next runner and 3
When the next runner is located on the same plane, there is a problem that the filling balance between the cavity leading to the backward tertiary runner and the cavity leading to the forward tertiary runner cannot be maintained. On the other hand, 1
Conventionally, there is a mold device provided with a vertical portion between the secondary runner and the secondary runner. However, if the vertical portion is provided, there is a problem that the entire mold device becomes large. Further, it is conceivable to change the temperature control for each cavity in order to balance the filling. However, there is a problem that the temperature control becomes complicated.

The present invention is intended to solve such a problem, and provides a multi-cavity mold device which can balance the filling of each cavity and can be reduced in size without using temperature control. The purpose is to:

[0010]

Means for Solving the Problems The present invention, in order to achieve the object, comprising a fixed mold and a movable mold for forming a plurality of cavities therebetween to open and close type closed each other, the solid
In a fixed form, both as having a manifold was only set the heater
The manifold has a runner branching from one resin injection port to each of the cavities.
A base runner of the resin injection port side, and an intermediate runner for two branches perpendicularly from the distal end of the base runner, reverse runner folded to the base runner side vertically 2 respectively branched from both ends of the intermediate runners And a forward runner directed to the opposite side, wherein the base runner, the intermediate runner, the reverse runner and the forward runner are on the same plane orthogonal to the fixed and movable mold opening and closing directions. In the multi-cavity mold device located at
The outer shape of the manifold is a recess located between the runners.
And the cross section of the forward runner is larger than the cross section of the reverse runner.

[0011]

[Action] In plurality cavity die apparatus of the present invention, during molding, solid
The fixed mold and the movable mold are closed, a plurality of cavities are formed between the fixed mold and the movable mold, and the resin injected from one resin injection port of the fixed mold is injected by a runner of a manifold having a heater. Branch and fill each cavity. Resin, in the runner, branching from the base runner to an intermediate runner, further branches in opposite directions runners and forward runners from both ends of the intermediate runners towards each cavity. By the way, when the base runner, the intermediate runner, the reverse runner and the forward runner are located on the same plane, the forward runner toward the opposite side is more resin than the reverse runner originally folded back to the base runner side. Is difficult to flow. On the other hand, by making the cross-sectional area of the forward runner larger than the cross-sectional area of the reverse runner, the difference in the fluidity of the resin to both runners is compensated and the resin is uniformly filled in each cavity. .

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the multi-cavity mold apparatus according to the present invention will be described below with reference to FIGS.
In FIG. 2, reference numeral 11 denotes a fixed mold, and 12 denotes a movable mold. The fixed mold 11 and the movable mold 12, which are molds, move in the vertical direction in the figure to open and close, and when the mold is closed, a total of eight cavities 13a, 1 are provided.
3b is formed between them.

The fixed die 11 has a first fixed-side receiving plate 17 fixed to the back (upper surface in the drawing) of a fixed-side die plate 16 that forms the cavities 13a and 13b. A second fixed-side receiving plate 18 is fixed to the back side of the second member. Further, a fixed-side mounting plate 20 that is mounted on a fixed-side platen of an injection molding machine is fixed to the back side of the second fixed-side receiving plate 18 via a fixed-side spacer block 19. A manifold 21 made of an integral member is provided between the second fixed-side receiving plate 18 and the fixed-side mounting plate 20 so as to be located inside the fixed-side spacer block 19.
Fixed through 22. Further, one sprue bush 26 to which the nozzle of the injection molding machine is connected is fixed to the manifold 21 through the fixed side mounting plate 20. The inside of the sprue bush 26 is a sprue 27 which is a resin injection port.

A runner branching from the sprue 27 to each of the eight cavities 13a and 13b is formed in the manifold 21. As shown in FIG. 1, the runner includes a cylindrical 0th-order runner 28 coaxially communicating with the sprue 27, and a cylindrical primary runner (base portion) vertically branched from the tip of the 0th order runner 28 into two parts. Runner) 29
And two vertically from both ends of the primary runner 29.
Branching cylindrical secondary runner (intermediate runner) 30
And three columnar tertiary runners 31a and 31b vertically bifurcated from both ends of these secondary runners 30, respectively. The distal ends of these tertiary runners 31a and 31b are bent vertically and The outlet portions 32a and 32b have a cylindrical shape and extend to the surface on the second fixed side receiving plate 18 side. The zero-order runner 28 and the outlets 32a and 32b have a direction parallel to the mold opening and closing directions of the fixed mold 11 and the movable mold 12, but the primary runner 29, the secondary runner 30, and the tertiary runner 31a and 31b are located on one plane orthogonal to the mold opening and closing direction. The tertiary runners 31a and 31b include a backward tertiary runner (reverse runner) 31a folded back to the primary runner 29 side and a forward tertiary runner (forward runner) 31b directed to the opposite side. While the cross-sectional diameter a of the reverse tertiary runner 31a is 8 mm, the forward
The diameter b of the cross section of the next runner 31b is 9 mm. That is, the cross-sectional area of the forward tertiary runner 31b is
It is larger than the cross-sectional area of the next runner 31a. The diameter c of the outlet 32a of the reverse tertiary runner 31a is also 8 mm, and the diameter d of the outlet 32b of the forward tertiary runner 31b is also 9 mm.
It is. Furthermore, primary runner 29 and secondary runner 30
Is 9 mm as in the case of the forward tertiary runner 31b.
The outer shape of the manifold 21 is the same as that of the runners 28, 29,
It is in line with the arrangement of 30, 31a, 31b, and has concave portions 33 on both sides located between the secondary runners 30 . Also,
Runners 28, 29, 30, 31a, 31b including outlets 32a, 32b
Is processed by a drill, but an unnecessary portion of the hole formed by the drilling is closed by a pad 37 held by a screw 36. As shown in FIG. 2, runners 28, 29, 30, 31a, 31b are provided on both sides of the manifold 21.
A sheath heater 38 for heating the thermoplastic resin inside is embedded.

The outlets 32a, 32b of the tertiary runners 31a, 31b communicate with the cavities 13a, 13b via a spear system 41, respectively. Spear system 41
Has a bush 42 fixed to the manifold 21 through the fixed-side receiving plates 17 and 18, and a body 43 built in the bush 42, and a heater is built in the body 43. The outlets 32a, 32b of the tertiary runners 31a, 31b are respectively connected to the cavities 13a, 1b via the resin passage 44 and the gate 45 in the spear system 41.
Leads to 3b. The paths from the sprue 27 to the cavities 13a and 13b are all equal. At the tip of the body 43, there is a chip located near the gate 45, and this chip has a built-in heater different from the heater of the body 43.

The movable die 12 has a movable receiving plate 52 fixed to the back (lower surface in the figure) of a movable mold plate 51 which forms the cavities 13a and 13b. A movable-side mounting plate fixed to the movable-side platen of the injection molding machine is fixed to the back side of the plate 52 via a movable-side spacer block. In addition, movable side receiving plate 52
A projecting plate provided with projecting pins 53 is movably provided between the movable plate and the movable-side mounting plate.

In actual use, FIGS. 1 and 2
Is the up-down direction.

Next, the operation of the above configuration will be described. At the time of molding, the fixed mold 11 and the movable mold 12 are closed, and cavities 13a and 13b are formed between the molds.
Inject thermoplastic resin such as BS resin or polystyrene. This resin contains sprue 27, zero-order runner 28,
Secondary runner 29, Secondary runner 30 and Tertiary runner 31
a, 31b, and from the outlets 32a, 32b, through the resin passage 44 of the spear system 41, and from the gate 45 into the cavities 13a, 13b. After the resin filled in the cavities 13a and 13b, that is, the product, is cooled and solidified, the fixed mold 11 and the movable mold 12 are opened, and the product is released by the ejection pin 53 and taken out. afterwards,
The mold is closed again, and the above molding cycle is repeated.

By heating the heater 38 of the manifold 21 and the heater of the body 43 of the spear system 41, the resin in the runners 28, 29, 30, 31a, 31b and the resin in the resin passage 44 is
It is kept molten at all times during the entire molding cycle. On the other hand, when the cavity 13a, 13b is filled with resin, the heating of the chip of the spear system 41 causes the resin in the gate 45 portion to be in a molten state and the gate 45 to be in an open state. At this time, the cooling of the chip of the spear system 41 causes the resin at the gate 45 to solidify and the gate 45 is closed.

By the way, as described above, the molten thermoplastic resin is vertically bent from the primary runner 29 to the secondary runner 30 in the manifold 21, and further from the tip of the secondary runner 30 in the reverse direction 3. Each of the cavities 13a and 13b branches into a next runner 31a and a forward tertiary runner 31b.
Head to b. At this time, primary runner 29, secondary runner 3
Since the 0 and tertiary runners 31a and 31b are located on the same plane, the primary runner is
The resin is less likely to flow to the forward runner 31b toward the opposite side than the reverse tertiary runner 31a folded back to the 29 side.
However, in the above embodiment, the diameter a of the backward tertiary runner 31a was 8 mm, which was smaller than the diameter b of the other runners including the forward tertiary runner 31b, that is, 9 mm. The difference in the fluidity of the resin to the runner 31a and the forward tertiary runner 31b is compensated, and the resin is uniformly filled in both the cavity 13a leading to the backward tertiary runner 31a and the cavity 13b leading to the forward tertiary runner 31b. . In this way, it is possible to balance the filling of the resin in each cavity 13 without increasing the temperature of the resin or changing the temperature control for each of the cavities 13a and 13b. Therefore, a product of stable quality having no difference in dimensions and the like can be obtained.

Further, since the primary runner 29, the secondary runner 30, and the tertiary runners 31a and 31b are located on the same plane, the manifold 21 can be made thinner, and the whole mold apparatus can be made smaller.

It should be noted that the present invention is not limited to the above embodiment, and various modifications can be made. For example,
Although the mold apparatus of the above-described embodiment has eight cavities, the number of cavities is not limited to eight. That is, the present invention has a runner shape in which the intermediate runner is bent from the distal end of the base runner, and the reverse runner and the forward runner directed to the opposite side are folded from the distal end of the intermediate runner to the base runner side. In addition, the present invention is generally useful for a multi-cavity mold apparatus in which the base runner, the intermediate runner, the reverse runner, and the forward runner are located on the same plane.

In the above embodiment, a hot runner mold apparatus for opening and closing a gate by a spear system has been described as an example. However, the present invention provides a valve gate type hot runner mold for mechanically opening and closing a gate. Applicable to devices. When using a spear system, there is a restriction on the resin passage from the runner of the manifold to the spear system,
In the case of the valve gate type, since the degree of freedom in designing the resin passage from the runner to the valve device is higher, the present invention can be implemented more effectively.

[0024]

According to the present invention, a manifold provided with a heater is provided.
The outer shape of the hold has a concave portion located between the runners.
This manifold is in line with the
De runners, a base runner resin inlet side, and an intermediate runner for two branches perpendicularly from the distal end of the base runner, perpendicularly respectively from both ends of the intermediate runner 2
A reverse runner and a forward runner directed to the opposite side that are branched and turned back to the base runner side, wherein the base runner, the intermediate runner, the reverse runner and the forward runner are fixed and movable mold opening and closing directions. Directly
Since the cross-sectional area of the forward runner was made larger than the cross-sectional area of the reverse runner in the multi-cavity mold device located on the same plane that intersected, resin was originally applied to the forward runner rather than the reverse runner. It is possible to compensate for the tendency to be difficult to flow, to balance the filling of each cavity without increasing the temperature of the resin itself or to change the temperature control for each cavity, and to uniformly fill the resin in each cavity. Also, as described above, the runner is fixed and
By being located on the same plane orthogonal to the mold opening and closing direction of the movable mold, the entire mold apparatus can be reduced in size.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a manifold showing one embodiment of a multi-cavity mold apparatus of the present invention.

FIG. 2 is a longitudinal sectional view of the same fixed type side.

FIG. 3 is an explanatory front view of an arrangement of runners showing an example of a conventional multi-cavity mold device.

FIG. 4 is an explanatory side view of an arrangement of runners showing another example of the conventional multi-cavity mold apparatus.

[Explanation of symbols]

11 Fixed mold (mold) 12 Movable mold (mold) 13a, 13b Cavity 21 Manifold 27 Sprue (resin injection port) 29 Primary runner (base runner) 30 Secondary runner (intermediate runner) 31a Reverse tertiary runner ( Reverse runner) 31b Forward tertiary runner (forward runner) 33 Recess 38 Heater

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B29C 45/26-45/44

Claims (1)

(57) [Claims] [Claim 1, further comprising a fixed mold and a movable mold for forming a plurality of cavities therebetween to open and close type closed each other, the solid
With a manifold equipped with a heater on the fixed form
The manifold has a runner branching from one resin injection port to each of the cavities.
A base runner of the resin injection port side, and an intermediate runner for two branches perpendicularly from the distal end of the base runner, reverse runner folded to the base runner side vertically 2 respectively branched from both ends of the intermediate runners And a forward runner directed to the opposite side, wherein the base runner, the intermediate runner, the reverse runner and the forward runner are on the same plane orthogonal to the fixed and movable mold opening and closing directions. In the multi-cavity mold device located at
The outer shape of the manifold is a recess located between the runners.
And a cross-sectional area of the forward runner is larger than a cross-sectional area of the reverse runner.