JP2003103580A - Injection molding tool, box-shape molded product, and method for manufacturing box-shape molded product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To securely fill a molten resin in every corner, even in thin wall parts. SOLUTION: In a cavity side half of a molding tool, a gate 13 is arranged at the inner corners of a cavity 3 and also at a position where the end of a side wall 32 of a shaped molded product 30, that is, at a position where four corners exist at the ends of the side wall 32. In addition, the gate 13 is of a circular shape and arranged so that its center position becomes a position where the side walls 32 of the cavity 3 cross each other. An ejector pin 23 is provided which releases the box-shape molded product 30 sticking to a projecting part 4a, when a framework of a movable half of the molding tool is released from a framework of the cavity side half.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection mold and a box-shaped molded product suitable for molding a molded product having a thin portion, and a method for manufacturing the same.

[0002]

2. Description of the Related Art In an injection molding die, a box-shaped molded product may be molded. Among such box-shaped molded products, for example, the box-shaped molded product used for a battery of a mobile phone has a thin plate shape as a whole battery, and therefore the molded product has a very thin top plate. There is.

[0003]

However, in the conventional injection molding die, when a box-shaped molded product is molded, when the molten resin is injected into the cavity from the gate provided at the center of the top plate, Since the portion corresponding to the top plate inside is an extremely thin space, it is difficult to flow the molten resin into every corner around the top plate in the cavity,
At a remarkable time, there was a problem that the molten resin was cured during the process of flowing into the top plate, resulting in defective products.

The present invention has been made in view of such circumstances, and an object thereof is to provide an injection molding die capable of surely filling molten resin in every corner even if there is a thin portion. It is to provide, and it aims at providing the box-shaped molded product shape | molded using the said metal mold | die. Moreover, the manufacturing method of this box-shaped background article is provided.

[0005]

In order to achieve the above object, the present invention proposes the following means. The invention according to claim 1 is an injection molding method for molding a box-shaped molded article having a polygonal top plate which is filled with molten resin and cured to form a polygonal shape, and side walls provided on each side of the top plate. In the molding die, a gate is provided at a corner of the cavity and at a position corresponding to an end face of a side wall of the box-shaped molded product.

According to the injection molding die of the present invention,
When molten resin is injected from the corner of the cavity, first,
After flowing into the relatively thick side wall side, it flows into the top plate side.
Moreover, on the top plate side, the top plate is sequentially filled from the corner portion side and from the side wall side that has already wrapped around to the center side, so that the whole top plate side is reliably filled.

According to a second aspect of the present invention, in the injection molding die according to the first aspect, there is provided a fixed mold structure having the gate, and a movable mold structure forming the cavity together with the fixed mold structure. A cavity convex portion is formed on an end surface of the fixed mold structure, and a cavity concave portion is formed on a surface of the movable mold structure facing the cavity convex portion.

According to the injection molding die of the present invention,
To surely form a cavity by the convex portion for the cavity formed on the end surface of the fixed mold structure and the concave portion for the cavity formed on the surface of the movable mold structure that faces the convex portion for the cavity. You can

According to a third aspect of the present invention, in the injection molding die according to the first or the second aspect, the fixed mold component is formed on the end face of the side wall of the box-shaped molded product at the time of releasing from the movable mold component. It is characterized by having an ejector pin which is pressed to release the box-shaped molded product from the fixed mold structure.

According to the injection molding die of the present invention,
At the time of mold release, the ejector pin can remove the box-shaped molded product from the convex part of the fixed mold structure, so that even if the molten resin comes into close contact with the convex part of the fixed side structure due to shrinkage, the molded box It is possible to easily and surely remove the molded article.

According to a fourth aspect of the present invention, in the injection molding die according to the third aspect, the ejector pin is mounted in the fixed mold component so as to be movable in the cavity direction,
It is characterized in that it has a driving means that moves into the cavity at the time of mold release.

According to the injection molding die of the present invention,
Since the ejector pin is driven by the driving means, the ejector pin can be reliably moved at a predetermined timing during mold release. The invention according to claim 5 is a box-shaped molded product having a polygonal top plate and side walls provided on each side of the top plate, and gate marks are provided on the end faces of the side wall corners. It is characterized by that. According to the box-shaped molded product according to the present invention, the gate mark is provided on the end face of the side wall corner portion, but since the thin top plate is formed by filling the molten resin from the side wall corner portion, the thin top plate is formed. It is possible to reliably obtain a molded product having The invention according to claim 6 is
A method for producing a box-shaped molded article having a polygonal top plate and side walls provided on each side of the top plate, which is obtained by filling a molten resin into a cavity of an injection molding die and curing the resin. ,
A box-shaped molded product is manufactured by injecting molten resin into the cavity from a position corresponding to an end surface of a side wall of the box-shaped molded product at a corner portion of the cavity and filling the cavity. And That is, when the molten resin is filled from the corners of the side walls, the molten resin flows from the corners of the side walls toward the top plate and the side wall, and on the top plate side, the molten resin is sequentially filled from the corners and the side walls to the center side. As a result, the entire top is reliably filled even with a thin top plate.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. 1 to 6 are views showing an injection mold according to an embodiment of the present invention, FIG. 1 is a vertical sectional view showing the injection mold, and FIG. 2 is a box-shaped molded product. FIG. 3 is a perspective view, FIG. 3 is a bottom view of the fixed-side mold showing the relationship between the cavity and the gate, FIG. 4 is a partially enlarged view of FIG. 3, FIG. 5 is a vertical cross-sectional view showing the vicinity of the ejector pin, and FIG.
[FIG. 3] is an explanatory diagram for demolding a molded product.

The injection mold shown in FIG. 1 is roughly divided into a fixed mold structure 1 and a movable mold structure 2 which moves vertically relative to the fixed mold structure 1. By moving and clamping the movable mold structure 2, cavities 3 for molding the box-shaped molded product 30 shown in FIG. 2 are formed between them.

A molded product 30 molded by this injection molding die will be described. As shown in FIG. 2, the molded product 30 includes a top plate 31 formed in a rectangular shape and a top plate 31 thereof. It has a side wall 32 provided upright on each side and is formed in a box shape. The box-shaped molded product (hereinafter, referred to as a box-shaped molded product) 30 accommodates a rechargeable battery for a mobile phone therein by being combined with a molded product (not shown) having a similar shape. It is like this. Such a box-shaped molded product 30 is formed thin, and the side wall 32 has a thickness of about 0.8 mm, and the top plate 31 has a thickness of 0.2 mm, for example. Therefore, the cavity is a box-shaped molded product 3 having the top plate 31 and the side wall 32.
It forms a space corresponding to 0.

The fixed mold structure 1 is composed of a fixed mold 4 and a fixed mold 4.
And a spacer block 5 to which the fixed mold 4 is fixed
And a fixed side receiving plate 6 attached to the upper surface of the spacer block 5, and the block 1 on the fixed side receiving plate 6.
1 side fixing plate 7 fixed through (see FIG. 5)
And a manifold 8 fixed between the fixed side receiving plate 6 and the fixed side mold 4 in the spacer block 5.
A runner 9, which is a passage for the molten resin, is provided inside the manifold 8, and the lower end of the runner 9 is the fixed-side template 4
It is connected to the runner 10 provided in the.

A heater 12 is provided on the outer peripheral portion of the runner 10.
Is provided, and a so-called hot runner is configured in which the molten resin in the runner 10 is always kept in a molten state by the heat of the heater 12. Further, the molten resin that has passed through the runner 10 is injected into the cavity 3 by passing through the gate 13.

The gate 13 is of a so-called valve gate type. That is, the valve pins 14 are provided in the runners 9 and 10 as shown in FIG. A cylinder piston 14a is provided above the valve pin 14 via a connecting body 14b.
a is a cylinder chamber 15 formed in the fixed side mounting plate 7.
It is set to be movable up and down.

At the time of molding, the cylinder piston 14 of the valve pin 14 is controlled by the hydraulic pressure supplied to and discharged from the cylinder chamber 15.
a moves upward, and the tip of the valve pin 14 moves to the gate 13
Is released, the molten resin can flow into the cavity 3. Then, when the pressure oil is supplied to and discharged from the cylinder chamber 15 in the opposite direction at the time when the molten resin is filled in the cavity 3, the valve pin 14 moves downward due to the oil pressure, and the tip end portion of the valve pin 14 becomes the gate. The gate 13 is inserted into the cavity 13 and the gate 13 is closed, whereby the molten resin in the cavity 3 and the molten resin in the runner 10 are cut.

Although not shown in detail, the upper end of the runner 9 is connected to a sprue (not shown) provided on the fixed side mounting plate 7.

Further, as shown in FIGS. 3 and 4, the gate 13 is located at a position corresponding to a corner of the cavity 3 in the fixed side mold 4 and at an end face of the side wall 32 of the shaped product 30. That is, it is provided at the corresponding positions of the four corners existing on the end surface of the side wall 32. The gate 13 has a circular shape and is arranged such that the center position thereof is a position where the side walls 32 of the cavity 3 intersect with each other. When the molten resin is injected, the cavity 3
It is possible to quickly flow into the top plate 31 side from the inner corner portion through the side wall 32 side.

On the other hand, the movable die structure 2 is arranged below the fixed side die 4 and the fixed side receiving plate 5 of the fixed die structure 2, and the movable side die 21 and the movable side attachment to which this is attached. And a plate 22.

Then, a convex portion 4a is provided on the lower surface of the fixed mold 4 of the fixed mold structure 1, and the movable mold structure 2 is provided.
A concave portion 21 a is provided on the upper surface of the movable side mold 21. In order to form the inner wall surface 33 of the side wall 32 of the box-shaped molded product 30, the lower surface of the stationary mold 4 is lowered by the height of the side wall 32 so that the convex portion 4a can be molded. Is formed by projecting to. The recess 21a is formed by recessing the movable mold 21 of the movable mold body 2 so that the front side of the box-shaped molded product 30 can be molded. The convex portion 4a and the concave portion 21a form the cavity 3 when the movable mold component 2 is in contact with the fixed mold component 1 and set in a predetermined position.

By the way, generally, when the molten resin is filled in the cavity 3 and hardened by being cooled, the molten resin contracts inward, so that it closely adheres to the convex portion 4a of the fixed side mold 4. Therefore, at the time of releasing the mold, the hardened box-shaped molded product 30 comes into a state of being in close contact with the convex portion 4a.

Therefore, an ejector pin 23 is provided for removing the box-shaped molded product 30 which is in close contact with the convex portion 4a when the movable mold structure 2 is released from the fixed mold structure 1. The ejector pin 23 is attached to the fixed mold structure 1 so as to be movable in the vertical direction, and the tip of the ejector pin 23 is convex when the mold is released.
The side wall 32 of the box-shaped molded product 30 that is in close contact with a is pressed downward.

That is, as shown in FIG. 5, the ejector pin 23 is long enough to pass through the fixed-side die 4, the manifold 6, the fixed-side receiving plate 7, the block 11, and the fixed-side mounting plate 7 of the fixed-type structure 1. It has an elongated shape, and has a protruding portion 23a formed in a flat shape and having a thickness dimension substantially similar to that of the side wall 32 of the box-shaped molded product 30 at the tip portion thereof.
This protruding portion 23a is, as shown in FIGS. 3 and 4,
In the fixed-side mold 4, it is arranged along the peripheral edge of the cavity 3 so as to face the four side walls 32 of the box-shaped molded product 30.

The upper portion 23b of the ejector pin 23 is
It is mounted in a cylinder chamber 17 formed in the fixed side mounting plate 7. Then, by supplying and discharging pressure oil (not shown) to the cylinder chamber 17, the ejector pin 23 is fixed to the fixed side mounting plate 7, the block 11, the fixed side receiving plate 6,
It moves downward in the manifold 8 and the fixed-side mold 4. Therefore, the ejector pin 23 at the time of release is
By moving downward by supplying / discharging the drive means composed of hydraulic pressure, the end face of the side wall 32 of the box-shaped molded product 30 is pressed downward so that the box-shaped molded product 30 can be released from the convex portion 4a.

The injection molding die of this embodiment is constructed as described above. At the time of molding, first, as shown in FIG. 1, a fixed mold structure 1 and a movable mold structure 2 are molded. After closing and forming the cavity 3 between the fixed mold structure 1 and the movable mold structure 2, the valve pin 14 is closed.
The gate 13 is released by moving it upwards away from.

Then, when a molten resin which is a molding material is injected from the sprue, the molten resin sequentially flows from the sprue through the runners 9 and 10 and further through the gate 13 to flow into the cavity 3.

At this time, since the gates 13 are provided at the corners of the end face of the side wall 32 of the box-shaped molded product 30 with respect to the cavity 3 in the fixed-side mold 4, the molten resin is used for the corners. When injected from a portion, it first flows into the side wall 32 side and then flows into the top plate 31 side. Moreover, on the top plate 31 side, the resin enters from the corner side of the top plate 31 corresponding to the gate 13 to the center side, and the resin also enters from the side wall 32 side that has already wrapped around, resulting in the top plate 31 side. The whole is surely filled.

Therefore, when the molten resin flows in from the corners of the side wall 32 in the cavity 3, both the side wall 32 and the top plate 31 are reliably filled with the molten resin, and the top plate 31 is circulated as in the prior art. Since it can be prevented from being hardened by, the box-shaped molded product 30 can be accurately molded even if the plate thickness of the top plate 31 is extremely thin.

When the cavity 3 is filled with a predetermined amount of the molten resin, the valve pin 14 is lowered and the gate 1 is closed.
3 is closed, and the molten resin in the cavity 3 is positively cooled by cooling water (not shown), so that the resin is rapidly cured.

When the molten resin filled in the cavity 3 is cured, the movable mold structure 2 is separated from the fixed mold structure 1. At this time, since the molten resin contracts inward, the box-shaped molded product 30 is brought into close contact with the convex portion 4a of the stationary-side mold 2 of the stationary mold structure 1 as shown in FIG. I will end up.

However, since the ejector pin 23 is slidably attached to the fixed mold body 1, when the movable mold body 2 is separated, the ejector pin 23 moves downward and the tip of the ejector pin 23 moves. Since the protruding portion 23a presses the end surface of the side wall 32 of the box-shaped molded product 30 downward, the box-shaped molded product 30 can be released from the convex portion 4a. Therefore, even if the molten resin comes into close contact with the convex portion 4a due to contraction, the molded box-shaped molded product 30 can be easily and reliably released from the mold. Moreover, the ejector pin 2
Since 3 is driven by a hydraulic drive unit, the ejector pin 23 can be reliably moved at a predetermined timing during mold release.

In the box-shaped molded product 30 molded as described above, traces of the gate 13, that is, so-called gate traces 40 are provided on the end faces of the side walls 32, but the molten resin is filled from the corners of the side walls 32. As a result, the top plate 31 is formed to have a predetermined thickness, so that the reliability as a product can be increased and the yield in molding can be improved. Further, the gate mark 40 has a shape which remains, but when combined with a molded product having a similar shape to this, the gate mark 40 is not seen from the surface and the appearance is not spoiled.

Therefore, by filling the cavity 3 with the molten resin from the corners of the end face of the side wall 32, the molten resin is surely filled in the space portion corresponding to the side wall 32 and the top plate 31 in the cavity 3, Moreover, since each has a constant thickness, reliability as a product can be enhanced and a molding yield can be improved.

[0037]

As described above, according to the first aspect of the present invention, when the molten resin is injected from the corners of the cavity, it flows into the side wall side and then flows to the top plate side. As a result of being sequentially filled from the corners of the top plate on the plate side and from the side wall side that has already wrapped around to the center side, the entire top plate side is reliably filled, and even if the top plate thickness is extremely thin, the box The effect that the shaped molded product can be accurately molded is obtained.

According to the second aspect of the present invention, the convex portion for the cavity formed on the end surface of the fixed die structure and the cavity formed on the surface of the movable die structure facing the convex portion for the cavity. The cavity can be surely formed by the concave portion for use.

According to the third aspect of the invention, since the ejector pin can remove the box-shaped molded product from the convex portion of the fixed mold component at the time of mold release, the molten resin contracts due to the contraction of the molten resin. Even if it comes into close contact with the convex portions of the above, the molded box-shaped molded product can be easily and reliably released from the mold.

According to the fourth aspect of the invention, since the ejector pin is driven by the driving means, the ejector pin can be reliably moved at a predetermined timing during mold release. According to the invention of claim 5, the gate marks are provided on the end faces of the side wall corners, but the reliability as a product can be improved and the yield in molding can be improved. According to the invention of claim 6, the molten resin is filled from the corners of the side wall, so that the resin flows from the corner of the side wall toward the top plate and the side wall, and on the top plate side, the corner and the side wall. As a result of being sequentially filled from the side to the center side, the entire top is reliably filled even with a thin top plate.

[Brief description of drawings]

FIG. 1 is a view showing an injection molding die according to an embodiment of the present invention, which is a vertical cross-sectional view showing the injection molding die.

FIG. 2 is a perspective view showing a box-shaped molded product.

FIG. 3 is a bottom view of a fixed-side mold showing a relationship between a cavity and a gate.

FIG. 4 is a partially enlarged view of FIG.

FIG. 5 is a vertical cross-sectional view showing the vicinity of an ejector pin.

FIG. 6 is an explanatory diagram when a molded product is released from a mold.

[Explanation of symbols]

1 Fixed type structure 2 Movable structure 3 cavities 4 Fixed mold 4a convex part of cavity 5 Spacer block 6 Fixed side support plate 7 Fixed side mounting plate 8 manifold 9,10 runner 11 blocks 12 heater 13 gates 14 valve pin 15,17 Cylinder chamber 21 Movable mold 21a cavity recess 22 Movable side mounting plate 23 Ejector pin 23a Ejector pin protrusion 23b Head of ejector pin 30 Box-shaped molded products 31 Top plate 32 side wall 33 Inner wall surface of side wall 40 gate mark

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Atsushi Takeishi             3-1-1 Koganecho, Niigata City, Niigata Prefecture Mitsubishi             Niigata Works, Material Co., Ltd. (72) Inventor Yoshihiro Horikawa             3-1-1 Koganecho, Niigata City, Niigata Prefecture Mitsubishi             Niigata Works, Material Co., Ltd. F-term (reference) 4F202 AH56 AM32 CA11 CB01 CK06                       CM02                 4F206 JA07 JN41 JQ81

Claims (6)

[Claims] 1. A mold for injection molding for molding a box-shaped molded article having a polygonal top plate and a side wall provided on each side of the top plate, which is filled with molten resin and cured in a cavity. In the injection molding die, the gate is provided at the corner of the cavity and at a position corresponding to the end face of the side wall of the box-shaped molded product. 2. The injection molding die according to claim 1, further comprising a fixed mold structure having the gate, and a movable mold structure forming the cavity together with the fixed mold structure. A mold for injection molding, characterized in that a convex portion for a cavity is formed on an end face, and a concave portion for a cavity is formed on a surface of the movable mold structure facing the convex portion for the cavity. 3. The mold for injection molding according to claim 1 or 2, wherein the fixed mold structure presses an end face of a side wall of the box-shaped molded product when the fixed mold structure is released from the movable mold structure. An injection molding die having an ejector pin for releasing a box-shaped molded product from a body. 4. The injection-molding die according to claim 3, wherein the ejector pin has a driving means that is movably mounted in the fixed mold structure in the cavity direction and that moves into the cavity when the mold is released. A mold for injection molding. 5. A box-shaped molded product having a polygonal top plate and side walls provided on each side of the top plate, wherein gate marks are provided on the end faces of the side wall corners. Box shaped molded product. 6. A box-shaped molded product having a polygonal top plate and side walls provided on each side of the top plate, which is obtained by filling molten resin into a cavity of an injection molding die and curing the resin. In the method, the molten resin is injected into the cavity from a position corresponding to the end face of the side wall of the box-shaped molded product at the corner portion of the cavity and the cavity is filled with the box-shaped molded product. A method for producing a box-shaped molded article, which comprises: