JP3196466B2 - Injection mold - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection mold having a pin-shaped valve for opening and closing a gate.

[0002]

2. Description of the Related Art A conventional example of this type of injection mold is shown in FIG.
And FIG. In the figure, reference numeral 1 denotes a fixed mold plate, 2 denotes a movable mold plate, 3 denotes a cavity formed between the fixed mold plate 1 and the movable mold plate 2, 4 denotes a cavity fitted to the fixed mold plate 1 and a cavity 3
, A gate bush provided with a gate 4a formed so as to face, a valve casing 6, and a valve 7 for opening and closing the gate 4a. The valve 7 is guided at its upper part by a guide bush 8 fixed to the valve casing 6 and at the lower part by a valve holder 10 fixed to the lower part of the valve casing 7 via a cap 9, thereby forming the gate 4 a. It moves up and down while being held coaxially with respect to. A band heater 1 is provided on the outer periphery of the valve casing 7.
The outer periphery of the band heater 11 is covered with a heater cover 12.

[0003] As shown in FIG. 3, the valve holder 10 has an outer ring portion 1 fitted to the inner peripheral surface of the valve casing 6.
0a and an inner ring portion 10b for slidably guiding the valve 7
And a plurality of blade portions 10c connecting the outer ring portion 10a and the inner ring portion 10b. A communication passage 13 is formed between the blade portions 10c to connect the resin passage 6a in the valve casing 6 to the gate 4a. I do.

Then, in the injection mold, the movable mold plate 2 is raised to be in a mold-clamped state as shown by a solid line in FIG.
The valve 7 is raised to open the gate 4a, and the molten resin is injected into the cavity 3 through the resin passage 6a in the valve casing 6 and the communication passage 13 of the valve holder 10 from the nozzle of the injection molding machine body (not shown). Let it. After the filling is completed, the valve 7 is lowered to close the gate 4a as shown by the solid line in the figure. After the resin in the cavity 3 is cooled and solidified, the movable mold plate 2 is lowered to open the mold, and the molded product is taken out.

[0005]

The above-mentioned conventional injection mold has the following problems. That is, there is a certain limit in securing the predetermined strength even if the thickness of the blade portion 10c and the inner ring portion 10b of the valve holder 10 is set to be thin. As described above, since the thickness of the blade portion 10c and the inner ring portion 10b of the valve holder 10 cannot be reduced to a certain degree or more, when the molten resin passes through the communication passage 13 formed between the blade portions 10c of the valve holder 10, Inevitably, flow path resistance is generated and smooth flow of the molten resin is hindered. When the smooth flow of the molten resin is hindered in this way, the molten resin tends to stay in the resin passage 6a in the valve casing 6 on the upstream side of the valve holder 10, and high-temperature burnt resin is extracted,
The retained molten resin undergoes deterioration such as carbonization under the influence of heat and adheres to the valve 7 as a carbide, so that there has been a problem that the resin cannot be removed when the valve 7 is replaced. In addition, there is a problem that the flow of the molten resin flowing downstream thereof is disturbed by the valve holder, bubbles are mixed into the cavity 3, or the filling density of the molten resin varies.

The present invention has been made in view of the above circumstances, and can prevent the molten resin from staying in the resin passage in the valve casing and deteriorating, and can prevent the molten resin from flowing downstream of the valve holder. It is an object of the present invention to provide an injection molding die capable of preventing the disturbance of the injection molding.

[0007]

According to the first aspect of the present invention, a cavity is formed between a pair of mold plates, and the cavity is formed in one of the mold plates through a gate facing the cavity. A cylindrical valve casing having a resin passage communicating with the valve casing is provided, and a pin-shaped valve is disposed in the resin passage of the valve casing so as to be movable in the axial direction. by being guided to move axially by a valve holder provided on parts, in the injection mold for opening and closing the gate by the tip of the valve, the bar
The lube has a gate closing part at the tip that closes the gate.
Having a valve body formed thereon, and an upper portion of the valve body having a valve body.
The shaft is guided by a guide bush fixed to the lube casing.
While being provided so as to be guided in the direction
By guiding the lower part of the body to the valve holder,
Configured to be held coaxially with the gate
The valve holder includes an outer ring portion fitted on the inner peripheral surface of the valve casing, an inner ring portion for slidably guiding the valve, and a plurality of blades connecting the outer ring portion and the inner ring portion. Bei <br/> example Rutotomoni the parts, fixed is the lower portion of the valve casing
In addition, at least the upstream end surface of the blade portion of the valve holder with respect to the direction in which the molten resin flows is formed in a tapered streamline shape.

According to the second aspect of the present invention, at least the end faces of the inner ring portion and the blade portion of the valve holder on the upstream side with respect to the direction in which the molten resin flows are formed in a tapered streamline shape. The configuration was adopted.

According to the third aspect of the invention, both the upstream and downstream end surfaces of the inner ring portion and the blade portion of the valve holder with respect to the flowing direction of the molten resin are tapered in a streamline shape. The configuration was formed.

[0010]

According to the first aspect of the present invention, since at least the upstream end face of the blade portion of the valve holder with respect to the direction in which the molten resin flows is formed in a tapered streamline shape, the flow from the upstream side is formed. The flow path resistance when the incoming molten resin passes between the blade portions of the valve holder is as small as possible.
Also, align the axis of the valve with the axis of the valve casing.
To keep the valve coaxial with the gate.
The valve tip to the gate
Can be opened and closed. And the axis of the valve is
To the axis of the casing, and furthermore the valve holder
At least with respect to the direction of flow of the molten resin
The streamline shape is provided on the end face on the upstream side
Gauge the molten resin uniformly and without pressure loss.
To the molten metal around the valve.
The flow rate of the fat becomes uniform, and it enters the cavity through the gate.
Injection balance can be made uniform.

In the second aspect of the present invention, at least the upstream end face of the inner ring portion and the blade portion of the valve holder with respect to the direction in which the molten resin flows is formed in a tapered streamline shape. The flow path resistance when the molten resin flowing from the upstream side passes between the blade portions of the valve holder is further reduced.

According to the third aspect of the present invention, the molten resin passes between the blade portions of the valve holder because the downstream portion is formed in a streamline shape without stopping at the upstream portion of the inner ring portion and the blade portion. And the molten resin flows smoothly into the cavity, which is the downstream side of the valve holder.

[0013]

An embodiment of the present invention will be described below with reference to the drawings. In these figures, reference numeral 20 denotes a fixed mold plate, and a movable mold plate 21 is provided so as to be openable and closable in opposition to the fixed mold plate 20. Then, a cavity 22 having a shape of a molded product is formed between the fixed mold plate 20 and the movable mold plate 21. The fixed mold plate 20 is fixed to a fixed mounting plate (not shown) via a first receiving plate 23a and a second receiving plate 23b, and the movable mold 21 is also fixed to a movable mounting plate (not shown).

A gate bush 24 is fixed in the fitting hole 20a of the fixed mold plate 20 in a state of being embedded. The gate bush 24 has a lower end exposed to the cavity 22, and an opening exposed to the cavity 22 corresponds to the gate 2.
4a.

A valve casing 26 is disposed inside the fixed mold plate 20 and the receiving plate 23 so that the tip side faces downward. A resin passage 27 extending in the vertical direction is formed inside the valve casing 26.
Is connected to the cavity 22 through the gate 24a of the gate bush 24, and the resin passage 2
The upper portion of 7 is communicated with a resin passage 30a in the manifold 30 through a communication passage 27a obliquely penetrating the upper portion of the valve casing 26, from which the molten resin is supplied.

A band heater 32 is provided on the outer periphery of the valve casing 26, and the outer periphery of the band heater 32 is covered by a heater cover 33. A vertical groove 34 is provided on the outer periphery of the valve casing 26, and a temperature sensor 35 is mounted in the vertical groove 34. A lead wire 35a extending from the temperature sensor 35 extends to a predetermined external location through a hole 36 formed in the second receiving plate 23b. Reference numeral 37 denotes an outer cylinder disposed outside the band cover 33.

In the resin passage 27 of the valve casing 26, a pin-shaped valve 38 extending through the manifold 30 along the central axis thereof is arranged so as to be movable in the vertical direction, and is driven up and down by a moving plate (not shown). You. The valve 38 includes a valve body 38a, a cylindrical gate closing portion 38b formed at the distal end of the valve body 38a and having an outer diameter slightly smaller than the opening diameter of the gate 24a, and a valve body 38a and a gate. And a conical portion 38c formed between the closing portion 38b. In the valve 38, the upper part of the valve body 38a is guided by the guide bush 39 fixed to the valve casing 26, and the lower part (tip) of the valve body 38a is fixed to the lower part of the valve casing 26. Is held coaxially with the gate 24a.

The valve holder 40 is inserted into a fitting hole formed in a lower portion of the valve casing 26, and the cap 4 screwed into the fitting hole of the valve casing 26 from below.
1 is fixed. The valve holder 40 is
As described above, the outer ring 40a, the inner ring 40b for slidably guiding the valve 38, the outer ring 40a and the inner ring 4
0b and a plurality of blades 40c connecting the
A communication passage 43 that connects the resin passage 27 in the valve casing 26 to the gate 24a is formed between the blade portions 40c.

As shown in FIG. 2, the upstream and downstream end surfaces 40ba and 40bb of the inner ring portion 40b of the valve holder 40 are tapered in cross section. It is formed in a streamlined shape. Here, the aforementioned both end surfaces 40ba of the inner ring portion 40b,
For 40bb, only the outer peripheral side is cut, whereby
The inner peripheral surface of the inner ring portion 40b for guiding the valve 38 is kept straight.

The upstream and downstream end surfaces 40ca, 40cb of the blade portion 40c of the valve holder 40 on the basis of the direction in which the molten resin flows are also formed in a tapered streamline shape. Here, as shown in FIG. 2C, the left and right sides of the blade 40c are cut so that the ridgeline is located at the center.

Next, the operation of the injection mold having the above configuration will be described. In order to obtain a resin molded product having a predetermined shape using the mold, first, the movable mold plate 21 is raised to a mold clamped state as shown by a solid line in the figure. Then, the valve 30 is raised to open the gate 24a, and molten resin is supplied from a nozzle of the injection molding machine main body (not shown) to the resin passage 30a in the manifold 30 and the resin passages 27a and 27 in the valve casing 26.
7 and communication passage 43 of valve holder 40 and gate 24
Inject into the cavity 22 through a. After the filling is completed, the valve 38 is lowered to close the gate 24a as shown by a two-dot chain line in the figure. And the cavity 22
After the resin inside is cooled and solidified, the movable mold plate 21 is lowered to open the mold, and the molded product is taken out from the cavity 22. This and
The axis of the valve 30 is aligned with the axis of the valve casing 26
And the valve 30 is coaxial with the gate 24a.
The gate is closed at the tip of the valve 30
The part 38b is correctly positioned on the gate 24a and the gate
24a is opened and closed. And the axis of the valve 30 is the valve
The valve holder 40 is aligned with the axis of the casing 26.
Upstream and downstream with respect to the direction of molten resin flow
Both end surfaces 40ba, 40bb are formed in a streamline shape
Can cause molten resin to be uniform and cause pressure loss.
To the gate 24a.
In the periphery, the flow rate of the molten resin becomes uniform, and the gate 2
Uniform balance of injection into cavity 22 through 4a
Can be achieved.

Here, the upstream and downstream end faces 40ba, 4b of the inner ring portion 40b and the blade portion 40c of the valve holder 40 with reference to the direction in which the molten resin flows.
Since 0bc, 40ca, and 40cb are formed in a streamline shape that is tapered, the molten resin flowing from the resin passage 27 side in the valve casing 26 receives the molten resin.
The flow path resistance when passing through the communication path 43 formed between the zero blade portions 40c can be minimized. Therefore, the flow of the molten resin when passing through the communication passage 43 and before and after the communication passage 43 can be kept smooth.

As a result, it is possible to prevent the molten resin from remaining in the resin passage 27 in the valve casing 26 on the upstream side of the valve holder 40 and undergoing the influence of heat, such as, for example, carbonization. Also, the valve holder 40
The molten resin smoothly flows into the cavity 3 which is the downstream side of the molten resin, so that it is possible to prevent bubbles from being mixed in the molten resin and variations in the filling density of the molten resin.

The present invention is not limited to the above-described embodiment, but can be modified as appropriate upon implementation. For example, in the above-described embodiment, four wings 40c of the valve holder 40 are provided, but the number of wings 40c is not limited thereto.
The present invention is also applicable to those having three or more than five.

In the above embodiment, the valve holder 40
Are formed in a streamline shape, but the present invention is not limited to this, and some of the plurality of blade portions 40c may be formed in a streamline shape.

In the above embodiment, the valve holder 40
End faces 40ba, 40bc, 40ca, 40c on the upstream and downstream sides of the inner ring portion 40b and the blade portion 40c, respectively.
Although b is formed in a streamline shape having a tapered shape, the present invention is not limited to this, and only the upstream end faces 40ba and 40ca of the inner ring portion 40b and the blade portion 40c may be formed in a streamline shape. . Further, the streamlined portion may be stopped only on the upstream side of the blade portion 40c which most contributes to the flow resistance of the molten resin.

[0027]

According to the first aspect of the present invention, the valve
Align the axis with the axis of the valve casing and
Can be held coaxially with the valve tip.
The gate can be positioned correctly on the gate to open and close the gate.
it can. Further, since at least the upstream end face of the blade portion of the valve holder on the basis of the direction in which the molten resin flows is formed in a streamline shape that is tapered, the molten resin flowing from the upstream side is a blade of the valve holder. The flow path resistance when passing between the sections can be minimized. For this reason, it is possible to prevent the molten resin from remaining in the resin passage in the valve casing on the upstream side of the valve holder and undergoing the influence of heat to change in quality such as carbonization. Ma
The axis of the valve is aligned with the axis of the valve casing.
At least the flow of molten resin in the blades of the valve holder
The end face on the upstream side with respect to the direction
By making the molten resin uniform and reducing the pressure loss
Guide to the gate without inviting
The flow rate of the molten resin becomes uniform
To achieve a uniform injection balance in all cavities.
it can.

According to the second aspect of the present invention, at least the upstream end face of the inner ring portion and the blade portion of the valve holder with respect to the flowing direction of the molten resin is formed in a tapered streamline shape. Therefore, the flow resistance when the molten resin flowing from the upstream side passes between the blade portions of the valve holder can be further reduced.

According to the third aspect of the present invention, the molten resin passes between the blades of the valve holder because it is formed not only at the upstream side of the inner ring portion and the blades but also at the downstream side in a streamline shape. Can be further reduced. Also, the molten resin flows smoothly into the cavity side, which is the downstream side of the valve holder, so that it is possible to prevent bubbles from being mixed into the molten resin flowing into the cavity and variations in the filling density of the molten resin. Can be avoided.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of an embodiment of the present invention.

2A and 2B are diagrams showing details of a valve holder used in one embodiment of the present invention, wherein FIG. 2A is a front view, FIG. 2B is a cross-sectional view, and FIG. 2C is a detailed cross-sectional view of a blade.

FIG. 3 is a cross-sectional view showing an example of a conventional injection mold.

4A and 4B are views showing a valve holder used in a conventional injection molding die, wherein FIG. 4A is a front view and FIG. 4B is a cross-sectional view.

[Explanation of symbols]

 Reference Signs List 20 fixed mold plate 21 movable mold plate 22 cavity 24a gate 26 valve casing 27 resin passage 38 valve 40 valve holder 40a outer ring portion 40b inner ring portion 40ba upstream end surface of inner ring portion 40bb downstream end surface of inner ring portion 40c blade portion 40ca Downstream end face of blade section 40cb Downstream end face of blade section 43 Communication passage

Claims (3)

(57) [Claims] 1. A cavity is formed between a pair of mold plates,
A cylindrical valve casing having a resin passage communicating with the cavity through a gate facing the cavity is provided in one mold plate, and a pin-shaped valve is movable in the axial direction in the resin passage of the valve casing. Placed in
In the injection molding die in which the distal end of the valve is guided by a valve holder provided at the distal end of the valve casing and moves in the axial direction, the gate is opened and closed by the distal end of the valve . Gate closing to close the gate at the tip
A valve body having a portion formed therein, and an upper portion of the valve body.
The guide bush fixed to the valve casing
While being provided so as to be guided in the axial direction.
The lower part of the lube body is guided by the valve holder
So that it is held coaxially with the gate.
The valve holder comprises an outer ring portion fitted on the inner peripheral surface of the valve casing, an inner ring portion for slidably guiding the valve, and a plurality of connecting the outer ring portion and the inner ring portion. Rutotomoni a blade portion, fixed to a lower portion of the valve casing
An injection mold , wherein at least the end face of the blade portion of the valve holder on the upstream side with respect to the flowing direction of the molten resin is formed in a tapered streamline shape. 2. The injection mold according to claim 1, wherein at least an upstream end face of the inner ring portion and the blade portion of the valve holder with respect to a flowing direction of the molten resin is tapered. A mold for injection molding characterized by being formed in a shape. 3. The injection molding die according to claim 1, wherein both the upstream and downstream end faces of the inner ring portion and the blade portion of the valve holder are tapered. A metal mold for injection molding characterized by being formed in a streamline shape as follows.