JP4224363B2 - Injection mold - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an injection mold provided with an edge nozzle having a branch gate that is provided in a hot runner and distributes and fills molten resin into a plurality of cavities.
[0002]
[Prior art]
An injection mold for molding a molded product is an edge that is provided with a plurality of cavities in one mold, distributes molten resin injected from a resin injection port, and communicates with the cavity in a heat-retaining state with a hot runner It is comprised so that it may guide to a nozzle.
[0003]
This injection mold is configured so that a plurality of molded products can be simultaneously molded by one injection molding, basically, one resin injection port in the sprue portion provided in the center portion, It has a branch passage that communicates with this and branches into a plurality of branches. On the other hand, the mold body is provided with a plurality of cavities, and a plurality of nozzle holder units having edge nozzles communicating with the cavities are provided. Further, a hot runner having a heater is connected to connect the branch passage of the sprue portion and each nozzle holder unit, and the injected molten resin is guided to the cavity in a heat retaining state.
[0004]
Accordingly, the molten resin injected from the resin injection port is distributed to a plurality of hot runners via the branch passages, led from these hot runners to the edge nozzles via the plurality of nozzle holder units, and further from the edge nozzles to the respective cavities. Injected into.
[0005]
FIG. 3 shows a part of a conventional injection mold, and the fixed mold 1 and the movable mold 2 are divided by a dividing surface 3. A resin injection port 5 is provided in the sprue portion 4 of the fixed mold 1 and molten resin is injected from an injection molding machine (not shown). A branch passage 6 that branches into a plurality of portions is provided in communication with the resin injection port 5.
[0006]
The branch passage 6 is connected to a hot runner 8 having a heater 7, and the resin passage 8 a of the hot runner 8 communicates with the cavity 10 via an edge nozzle 9 having branch gates 9 a and 9 b branched into two branches. ing. The cavity 10 is constituted by a gap between a cavity outer cylinder portion 11 provided in the fixed mold 1 and a cavity inner cylinder portion 12 provided in the movable mold 2 and inserted into the cavity outer cylinder portion 11. ing.
[0007]
Further, a resin heat insulating layer 13 that communicates with the branch gates 9 a and 9 b is formed around the edge nozzle 9, and the resin heat insulating layer 13 communicates with the cavity 10 via the gate 14. A plurality of cooling water channels 18 are provided around the cavity 10 in parallel therewith. The cooling water channel 18 is cylindrical and has a structure in which a partition plate 19 is provided in the axial direction. A cooling water inlet 18a is provided on one end side of the cooling water channel 18 and a cooling water return is provided on the other end side. A portion 18b is provided. Then, the cooling water supplied from the cooling water inlet 18a of the cooling water channel 18 flows through one of the water channels partitioned by the partition plate 19, and circulates so as to flow back through the other water channel from the cooling water return portion 18b to circulate the cavity 10. The molten resin filled in is cooled.
[0008]
The injection mold described above is a mold for forming a writing instrument or the like, and the molded product 20 formed by filling the cavity 10 with resin is provided at the cylindrical portion 20a and the base end portion of the cylindrical portion 20a. It consists of the protrusion part 20b. The protrusion 20 b is located on the dividing surface 3 between the fixed mold 1 and the movable mold 2.
[0009]
[Problems to be solved by the invention]
However, in the injection mold configured as described above, the resin heat insulating layer 13 communicating with the branch gates 9 a and 9 b is formed around the edge nozzle 9, and the resin heat insulating layer 13 is connected to the cavity 10 via the gate 14. Communicating with
[0010]
Accordingly, the branch gates 9a and 9b communicate with each other through the resin heat insulating layer 13 and are in a state where the molten resin can come and go. For this reason, the resin from the resin passage 8a of the hot runner 8 is not uniformly distributed to the branch gates 9a and 9b, the resin pressure of the molten resin toward the cavities 10 varies, and the quality of the molded product varies. Sometimes.
[0011]
The present invention has been made paying attention to the above circumstances, and the purpose thereof is to prevent movement of the resin of the resin heat insulation layer, and the molten resin from the resin passage of the hot runner to each branch gate of the edge nozzle An object of the present invention is to provide an injection mold that can obtain a molded product that is uniformly distributed and has a constant quality.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, according to a first aspect of the present invention, there is provided a fixed mold, a movable mold that can be brought into and out of contact with the fixed mold, and a resin injection provided in the fixed mold. It comprises a hot runner having an inlet and a resin passage communicating with the resin inlet, and an edge nozzle having a branch gate provided in the hot runner for distributing and filling molten resin into a plurality of cavities,
Resin that stores a molten resin from a branch gate of the edge nozzle between the outer peripheral surface of the edge nozzle and the inner peripheral surface of the cavity portion provided with a hollow portion in the fixed mold around the edge nozzle A heat insulating layer is formed, and within this resin heat insulating layer, the resin in the resin heat insulating layer is prevented from moving to the center of the lower surface of the edge nozzle, and the resin pressure from the resin passage of the hot runner is applied to each branch gate. The present invention provides an injection mold characterized in that a partition portion for uniform distribution is provided.
[0013]
According to a second aspect of the present invention, the edge nozzle according to the first aspect is made of a heat conductive alloy, and the partition portion is provided integrally with the edge nozzle.
[0014]
A third aspect of the present invention is characterized in that the edge nozzle of the first aspect is fixed to the hot runner via a suspension bolt.
[0015]
According to the above configuration, when the molten resin is filled into the cavity from the branch gate through the gate, a part of the semi-molten resin in the resin heat insulating layer is filled into the cavity together with the injected molten resin. The At this time, the inside of the resin heat insulating layer is partitioned between both branch gates by a partition portion provided in the edge nozzle. Therefore, for example, the resin pressure on the left branch gate side becomes higher than the resin pressure on the right branch gate side, and the molten resin in the resin heat insulation layer moves from the left side to the right side, or vice versa. It is possible to prevent the molten resin from moving from the right side to the left side.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0017]
FIG. 1 is a vertical side view of an injection mold, and FIG. 2 is a perspective view of an edge nozzle. The injection mold 21 is a mold for forming a shaft portion of a writing instrument or the like. As shown in FIG. 1, a single mold main body 22 can simultaneously mold a plurality of molded products. 23 is provided.
[0018]
The molding part 23 will be described. The fixed mold 24 and the movable mold 25 are divided by a dividing surface 26. A resin injection port 28 is provided in the sprue portion 27 of the fixed mold 24, and molten resin is injected from an injection molding machine (not shown).
[0019]
A branch passage 29 that branches into the plurality of molding portions 23 is provided in communication with the resin injection port 28. The branch passage 29 communicates with the resin passage 31 of the hot runner 30. A heater 32 is wound around the outer peripheral surface of the hot runner 30.
[0020]
An edge nozzle 33 is provided in the resin passage 31 of the hot runner 30. The edge nozzle 33 has a cylindrical portion 33b having a resin passage 33a communicating with the resin passage 31 and a widening portion 33c that is widened toward the end and is provided integrally with the cylindrical portion 33b. The widened portion 33c is provided with a plurality of branch gates 34a and 34b that branch into two branches in the present embodiment, corresponding to the number of molding portions 23. These branch gates 34 a and 34 b communicate with the gate 35.
[0021]
A female threaded portion 36 is provided on the inner peripheral surface of the cylindrical portion 33 b of the edge nozzle 33, and the female threaded portion 36 is screwed and fixed to a male threaded portion 37 a of a suspension bolt 37 embedded in the hot runner 30. That is, even if resin pressure is applied to the edge nozzle 33, the edge nozzle 33 is prevented from falling downward in the drawing.
[0022]
As shown in FIG. 2, the edge nozzle 33 is formed of, for example, a heat conductive alloy such as Be—Cu, and is divided into a fixed mold 24 side and a movable mold 25 side to form a gate portion. Yes. The dividing line 33 d of the edge nozzle 33 is provided so as to be coincident with or close to the dividing surface 26 between the fixed mold 24 and the movable mold 25.
[0023]
Further, a cavity 24 a is provided in the stationary mold 24 around the outer periphery of the edge nozzle 33. A resin heat insulating layer 38 is provided around the inner peripheral surface of the cavity 24 a and the branch gates 34 a and 34 b of the edge nozzle 33 . In the resin heat insulating layer 38, when molten resin is injected from the branch gates 34a and 34b through the gate 35 into a cavity 39 to be described later, a part of the semi-molten resin of the resin heat insulating layer 38 is simultaneously injected into the cavity 39. It has come to be.
[0024]
Further, a partition piece 40 as a partition part for partitioning the resin heat insulating layer 38a on the branch gate 34a side and the resin heat insulating layer 38b on the branch gate 34b side is projected from the center portion of the lower surface of the edge nozzle 33. The front end surface of the partition piece 40 is close to or in contact with the upper surface of the edge nozzle 33 on the movable mold 25 side, and the molten resin in the resin heat insulating layers 38a and 38b is moved to the left and right in the drawing by the partition piece 40. Is blocking.
[0025]
On the other hand, the cavity 39 has a cylindrical shape between a cavity outer cylinder portion 41 provided in the fixed mold 24 and a cavity inner cylinder portion 42 provided in the movable mold 25 and inserted into the cavity outer cylinder portion 41. It is comprised by the gap | interval of. A spiral cooling water channel (not shown) is provided on the outer peripheral surface of the cavity outer cylinder portion 41 over the entire length, so that the molten resin filled in the cavity 39 is uniformly cooled from the outside.
[0026]
Furthermore, a pipe 46 is concentrically provided in the axial direction in the inner cavity 42a of the inner cylinder portion 42 with a gap 45 on the outer peripheral surface. The pipe 46 is provided with a cooling water forward path 47, and the gap 45 is provided with a cooling water return path 48 that communicates with the cooling water forward path 47 at the tip of the pipe 46. The cooling water forward path 47 communicates with the discharge side of a cooling water supply source (not shown), and the cooling water return path 48 constitutes a cooling water circulation path communicating with the suction side of the cooling water supply source. The molten resin filled in the cavity 39 is uniformly cooled from the inside.
[0027]
Next, the operation of the injection mold configured as described above will be described.
[0028]
When molten resin is injected from the injection molding machine into the injection mold from the resin injection port 28, the molten resin is guided to the resin passage 31 of the hot runner 30 through the branch passage 29.
[0029]
The molten resin in the resin passage 31 is guided from the hot runner 30 to the branch gates 34a and 34b via the edge nozzle 33 resin passage 33a, and the gate 35 is passed through the resin heat insulating layer 38 provided around the edge nozzle 33. And the cavity 39 is filled. That is, when the molten resin is filled into the cavity 39 from the branch gates 34a and 34b through the gate 35, a part of the semi-molten resin in the resin heat insulating layer 38 is put together with the injected molten resin into the cavity 39. Filled.
[0030]
At this time, in the resin heat insulation layer 38, the resin insulation layer 38a on the branch gate 34a side and the resin heat insulation layer 38b on the branch gate 34b side are partitioned by the partition piece 40 provided on the edge nozzle 33. Therefore, for example, the resin pressure on the left branch gate 34a side becomes higher than the resin pressure on the right branch gate 34b side, and the molten resin in the resin heat insulating layer 38a moves from the left side to the right side, or vice versa. It is possible to prevent the molten resin in the resin heat insulating layer 38b from moving from the right side to the left side. Therefore, the resin pressure of the molten resin filled in the cavity 39 from the left and right branch gates 34a and 34b can be equalized, and a molded product having no variation in quality can be formed.
[0031]
On the other hand, at this time, since the cooling water channel is provided so as to surround the outside of the cavity 39, the molten resin filled in the cavity 39 is uniformly cooled from the outside. Inside the cavity 39, a cooling water circulation path 49 is formed in which the cooling water flowing in from the cooling water supply source flows through the cooling water forward path 47, is folded at the tip of the pipe 46, and flows to the cooling water return path 48. The molten resin filled in 39 is evenly cooled from the inside.
[0032]
Therefore, the resin in the cavity 39 is cooled and solidified in a short time. After the resin is cooled and solidified, when the movable mold 25 moves backward with respect to the fixed mold 24, the fixed mold 24 and the movable mold 25 are divided by the dividing surface 26, and a molded product following the shape of the cavity 39 is obtained. can get.
[0033]
In the present embodiment, the case where the edge nozzle 33 is provided with the two branch gates 34a and 34b has been described, but the present invention can also be applied to the case where three or four branch gates are provided.
[0034]
In the above-described embodiment, the writing instrument such as the shaft of the ball-point pen has been described.
[0035]
Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Moreover, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, you may combine suitably the component covering different embodiment.
[0036]
【The invention's effect】
As described above, according to the configuration of the present invention, the movement of the molten resin in the resin heat insulation layer can be prevented by providing the partition portion in the resin heat insulation layer provided around the edge nozzle. Therefore, the molten resin is uniformly distributed from the resin passage of the hot runner to each branch gate of the edge nozzle, and a molded product having a constant quality can be obtained.
[0037]
Furthermore, when distributing to a plurality of branch gates from a single resin passage, molten resin can be easily blown out from a large gate even with a slight dimensional error around the gate, but evenly distributed by providing a partition in the resin heat insulation layer. Can be made.
[Brief description of the drawings]
FIG. 1 is a longitudinal side view of an injection mold showing a first embodiment of the present invention.
FIG. 2 is a longitudinal side view showing the embodiment and enlarging a part A of FIG. 1;
FIG. 3 is a vertical side view of a conventional injection mold.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 24 ... Fixed mold, 25 ... Movable mold, 26 ... Dividing surface, 28 ... Resin inlet, 30 ... Hot runner, 31 ... Resin passage, 34a, 34b ... Branch gate, 33 ... Edge nozzle, 38 ... Resin heat insulation layer , 39 ... cavity, 40 ... partition piece (partition part)

Claims (3)

A fixed mold, a movable mold that can be brought into contact with and separated from the fixed mold by the dividing surface 6, a hot runner having a resin injection port provided in the fixed mold and a resin passage communicating with the resin injection port, It consists of an edge nozzle having a branch gate that is provided in this hot runner and distributes and fills molten resin into a plurality of cavities,
Resin that stores a molten resin from a branch gate of the edge nozzle between the outer peripheral surface of the edge nozzle and the inner peripheral surface of the cavity portion provided with a hollow portion in the fixed mold around the edge nozzle A heat insulating layer is formed, and the resin pressure from the resin passage of the hot runner is applied to each branch gate by preventing the movement of the resin in the resin heat insulating layer at the center of the lower surface of the edge nozzle inside the resin heat insulating layer. An injection mold characterized by providing a partition portion for uniform distribution. 2. The injection mold according to claim 1, wherein the edge nozzle is made of a heat conductive alloy, and the partition portion is provided integrally with the edge nozzle. The injection mold according to claim 1, wherein the edge nozzle is fixed to the hot runner via a suspension bolt.

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