JPH11138557A - Injection mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain mirror-finished surfaces without polishing the surface of a product and reduce the production cost of the product by a method wherein the wall surface of a cavity is made of a thin plate having a dense surface and a backing member for supporting the thin plate is provided on the back surface side of the thin plate. SOLUTION: In this injection mold, a fixed mold block 1, at the center of which a recessed part 1a is provided, and a movable mold block 2 are arranged opposite to each other. On the inner surface of the movable mold block 2, a frame-like damming block 3 is installed, while, on the inner surface of the fixed mold block 1, a frame-like guide block 4 is installed. In the respective recessed parts 1a and 2a of the fixed mold block 1 and of the movable mold block 2, mold inserts 5a and 5b are fitted. The surfaces contacting with a molding of the mold inserts 5a and 5b are made of glass plates 6a and 6b. The back surface sides of the glass plates 6a and 6b are so constituted as to be supported by backing members 7a and 7b in order to prevent the glass plates 6a and 6b from being elastically deformed. By casting the backing members 7a and 7b in the required molds, the glass plates 6a and 6b at the surface of the backing members are molded integrally with the backing members.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection molding die used for plastic injection molding.

[0002]

2. Description of the Related Art In injection molding dies of this type, it is most common to use a steel material for a molding surface, and dies using other materials include resin dies, aluminum dies, ZAS dies, and the like. It has been known. By the way, in order to obtain a mirror molded product,
In the case of a steel mold, the polishing accuracy of the surface of the mold is increased so that the surface is completely mirror-finished. In order to maintain the mirror-polished mold, great care is taken to prevent rust and fogging. on the other hand,
In the case of a mold made of a simple mold material such as a resin mold, an aluminum mold, or a ZAS mold, it is difficult to improve the surface accuracy by mirror polishing or the like.

[0003]

However, there is a problem that the mirror finishing as described above is costly and difficult to maintain, and that the mold material capable of the mirror finishing is limited to some extent. . In particular, when the molded product has a complicated shape, the machining cost is further increased. On the other hand, when an inexpensive mold material is used, the polishing accuracy cannot be improved as described above, and thus it is not suitable for molding a transparent component, for example.

[0004] The present invention has been made in view of the above problems, and an object of the present invention is to provide an injection molding die capable of obtaining a mirror surface without polishing the surface and greatly reducing the cost. It is the purpose.

[0005]

In order to achieve the above object, an injection molding die according to the present invention comprises:
The cavity wall surface is formed of a dense thin plate, and a backing member for supporting the thin plate is provided on the back side of the thin plate.

According to the present invention, since the thin plate having a dense surface is supported by the backing member serving to suppress the elastic deformation of the thin plate and the mold is formed, the surface of the mold is not polished. A mirror surface can be easily obtained. Therefore, the mirror processing cost is not required, and it is possible to cope with a complicated shape, thereby making it possible to significantly reduce the cost. Further, even when the mold is damaged, the shape can be easily changed even when the model is changed, and even when the model is changed, the shape of the molded product can be easily changed.

In the present invention, it is preferable that the thin plate is a flat glass plate of float glass or polished glass or a formed glass plate. By doing this,
The cost of the mold can be reduced by utilizing the smoothness of the glass surface, and a mold utilizing the flatness of the glass or the curved surface shape of the processed glass can be obtained. Also, for example, when molding a glass molded body such as a laminated glass, this glass molded body itself is used as a model, glass as a thin plate is placed on the surface of a mold, and a backing member is poured into the back side of the glass. In addition, a mold in which an error at the time of glass molding is incorporated can be easily manufactured without machining the mold again.

[0008] The thin plate may be made of any material of polycarbonate, acrylic and SMC. Further, the thin plate may be an electroformed member formed by transferring an electroformed method from a glass plate processed into a predetermined shape. The mold using the electroformed member in this manner is suitable for a mold requiring thermal shock resistance, for example, such as molding of polycarbonate, and the metal member is transferred from the surface of the glass plate by the electroforming method. Can be easily and inexpensively manufactured by attaching the to the molded product surface of the mold. Further, the thin plate may be a metal plate formed using a forming die whose cavity wall surface is formed of a glass plate.

Preferably, a coating layer for facilitating release is applied to the surface of the thin plate. For example, when a glass plate is used as a thin plate, there is a possibility that the adhesiveness between the glass plate and the molding resin may increase.Therefore, by applying such a coating layer, the adhesion between such a thin plate and the molding resin may be improved. The problem can be solved.

In the present invention, the backing member is preferably made of epoxy resin or cement. With this configuration, the thin plate can be prevented from being elastically deformed, and the backing member can be formed by pouring, so that the mold can be easily and inexpensively manufactured.

In the present invention, it is preferable that a local heating means for locally heating the surface of the thin plate is provided. For example, when a glass plate is used as a thin plate, the heat insulating property is increased, and a thinner wall can be formed.On the other hand, the cooling cycle may be delayed and the forming cycle may be longer. In addition, only the surface of the thin plate is locally heated to minimize the heating, thereby preventing the cooling from being delayed. In this case, it is preferable to select the local heating means that heats the surface of the thin plate by coating the surface of the thin plate with a current-carrying heating material. Such a heating means is most suitable when the thin plate is a glass plate. Further, the local heating means may heat the surface of the thin plate by embedding a sheet heater on the back surface side of the thin plate. According to such a sheet heater, since it is sheet-like, it is easy to mount the thin plate on the back surface side. Further, the local heating means may heat the surface of the thin plate by embedding a copper pipe on the back surface side of the thin plate.
Such a copper pipe is easy to construct and inexpensive.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a specific embodiment of an injection mold according to the present invention will be described with reference to the drawings.

FIG. 1 shows a sectional view (a) of an injection mold according to one embodiment of the present invention and a sectional view (b) of a mold insert.

The injection mold according to the present embodiment comprises a fixed block 1 having a recess 1a at the center and a movable block 2 also having a recess 2a at the center. I have. On the inner surface of the movable block 2, a frame-shaped damming block (inclining slide) 3 is mounted so as to surround the recess 2 a, and on the inner surface of the fixed block 1, the outer peripheral surface of the damping block 3 A frame-shaped guide block 4 for guiding the guide is mounted. And
Mold nests 5a and 5b as shown in FIG. 1B are fitted in the recesses 1a and 2a of the fixed block 1 and the movable block 2, respectively.

The surfaces of the mold inserts 5a and 5b that are in contact with the molded product are formed of glass plates (thin plates) 6a and 6b, and the back sides of the glass plates 6a and 6b are elastically deformed by the glass plates 6a and 6b. The structure is supported by backing members 7a and 7b for preventing deformation. here,
As the glass plates 6a and 6b on the surface, a flat glass plate of float glass or polished glass or a formed glass plate is used. As the backing members 7a and 7b, a thermoplastic resin such as an epoxy resin or cement is used, and these are poured into a required mold to be integrally formed with the surface glass plates 6a and 6b.

The surfaces of the glass plates 6a, 6b are coated with a current-carrying material so that only the surfaces can be heated. In addition, as the electric heating material coated on the surface, Ti, Zr,
Preferred are nitrides, carbides or borides of Hf, V, Nb, Ta, Cr, Mo, W. Further, the surfaces of the glass plates 6a and 6b are subjected to fluorine processing in order to improve releasability from the molding resin.

Next, a manufacturing process for forming a laminated glass (a molded product in which a resin is sandwiched between two glass plates) using the above-described injection mold will be described.

(1) Installation Step With respect to a fixed mold consisting of the fixed mold block 1 and the mold insert 5a, the movable mold consisting of the movable mold block 2 and the mold insert 5b is opened. In the above, two sheet glasses are held so as to be in contact with the surfaces of the glass plates 6a and 6b of the mold inserts 5a and 5b, and a gap is formed between the held glass and the surfaces of the glass plates 6a and 6b. Install it closely so that it does not occur.

(2) Mold Closing / Movable Mold Locking Step The movable mold is moved forward with respect to the fixed mold until a predetermined interval l ₁ is reached to lock the movable mold. Subsequently, the movable mold is compressed and moved forward with respect to the fixed mold until an interval of l ₂ (l ₂ <l ₁ ) is reached.

[0020] (3) in the presence of the distance l ₂ white compressed against the stationary mold an injection supply step movable mold, while opening operation and closing valve (not shown) are provided in the nozzle portion of the injection unit, By moving a screw (not shown) forward, a molten resin material is injected and supplied into the mold cavity 11 through the sprue 8, the runner 9 and the gate (side gate) 10.

[0021] (4) by a distance of l ₂ white compression while maintaining the parallel state of the molds the movable mold to the stationary mold side while the molten resin material into the mold cavity shrinking step mold cavity 11 by injection supply By moving it forward, the cavity volume of the mold cavity 11 is contracted. by this,
The entire molten resin material injected and supplied is spread while uniformly applying a pressure (a pressure sufficient to suppress a gas contained in the molten resin material from growing as bubbles). In addition, the amount of the molten resin material necessary for molding is
When the fuel is injected and supplied into the valve 1, the valve is closed.

(5) Cooling Step In a state where the cavity volume of the mold cavity 11 is reduced, the expanded molten resin material is cooled while applying a pressure, and is joined to the glass surface inserted into the mold. Until compressed.

(6) Mold Opening Step The lock of the movable mold is released, the movable mold is moved backward, and the molded product is taken out of the mold.

According to this embodiment, since the surface of the injection mold is formed of a dense glass plate, a mirror surface can be easily obtained without polishing the surface of the mold.
Therefore, the mirror processing cost is not required, and it is possible to cope with a complicated shape, thereby achieving a significant cost reduction. In order to produce the mold nests 5a and 5b, the laminated glass itself produced in the above-described production process is used as a model, a glass plate is placed on the surface of the mold, and the backing member is placed on the back of the glass. By pouring into the side, there is no need to form a mold again by machining other than the mold for processing this glass plate, and it is easy to manufacture a mold that incorporates errors at the time of glass molding. it can. In this way, the cost for manufacturing the mold can be significantly reduced. Further, it is easy to change setups in small-lot production of many kinds, and it is possible to easily change a molded product while the mold is mounted on the molding machine.

Further, according to the present embodiment, it is possible to universally cope with molded products of various sizes and shapes simply by replacing the mold inserts, and each mold is provided with an expensive mold one by one. There is also an effect that there is no need to prepare.

Since the low pressure molding can be performed by using the injection press molding method as in this embodiment, even if a glass plate is used on the surface of the mold, the glass plate may be damaged by an excessive force. Never do. On the other hand, according to the conventional injection molding method, the molding pressure is large, and there is a possibility that the glass is broken by a thermal shock or the like.

In this embodiment, the glass plate 6
Since the surfaces of the glass plates 6a and 6b are coated with the electric heating material, only the surfaces of the glass plates 6a and 6b can be locally heated. Therefore, since the heating can be minimized, it is possible to avoid the problem that the cooling cycle is delayed and the molding cycle is lengthened.

FIG. 2 shows another embodiment of the present invention using the electroforming method. (A) is an explanatory view of a transfer mode by an electroforming method, and (b) is a sectional view of a mold insert.

In the present embodiment, the glass plate 11 (the glass plates 6a, 6a
The electroformed members 12a and 12b are manufactured by an electroforming method using a model (a matrix) similar to that of (b). That is, after an electrodeposited metal such as nickel is applied to a required thickness on the glass plate 11 by electrolysis, the electrodeposited metal is peeled off from the glass plate 11 to form an electroformed member having a concavo-convex reverse to the glass plate 11. By making and repeating the same operation with the reverse type,
This is for producing the same electroformed members 12a and 12b as the matrix.

The electroformed members 12a, 12
In the same manner as in the previous embodiment, b is molded integrally with backing members 7a and 7b such as epoxy resin or cement to form mold nests 13a and 13b.
a and 13b are respectively fitted into the recesses 1a and 2a of the fixed mold block 1 and the movable mold block 2 in the same manner as described above to form a mold.

When a glass plate is used for the molding surface as in the previous embodiment, the thermal shock resistance of the glass plate may become a problem depending on the molding material, for example, when molding polycarbonate. In such a case, it is preferable to use the electroformed members 12a and 12b as in this embodiment. In the case of this embodiment as well, there is an effect that a mold can be manufactured easily and inexpensively.

As a material constituting the molding surface of the mold, in addition to the above-mentioned glass plate and electroformed member, for example, polycarbonate, acrylic or SMC (Sheet Mold)
various materials such as in-g Compound). Further, the thin plate may be a metal plate formed using a forming die whose cavity wall surface is formed of a glass plate.

In the above embodiment, the local heating means for heating the surface of the thin plate is described as being coated with a current-carrying heating material. However, this local heating means is provided by embedding a sheet heater on the back side of the thin plate. What heats the surface of a thin plate may be sufficient. According to such a sheet heater, since it is sheet-like, it is easy to mount the thin plate on the back surface side. Further, the local heating means may heat the surface of the thin plate by embedding a copper pipe on the back surface side of the thin plate. When burying this copper pipe, set the copper pipe so as to be sandwiched between the electroformed shell and the wire mesh, temporarily fix it with a welding machine, and then perform nickel electroforming or copper electroforming until the wire mesh is clogged, And a copper pipe. There is an advantage that such a copper pipe can be easily constructed and inexpensive.

In the above embodiment, the heating means for locally heating the surface of the thin plate is described. In addition to such heating means, a cooling means is provided on the mold block side of the heating means. Is preferable from the viewpoint of shortening the molding time. FIG. 3 shows another embodiment of such a temperature control circuit (heating circuit and cooling circuit). In this example, an independent temperature control circuit 15 for heating is buried in the backing members 14a, 14b at a position close to the surface of the mold, and the side close to the fixed block 1 and the movable block 2 and the damming block. An independent temperature control circuit 16 for cooling is embedded in 3. Note that what is indicated by reference numeral 17 is a heat insulating plate.

[Brief description of the drawings]

FIG. 1 is a sectional view (a) of an injection mold and a sectional view (b) of a mold insert according to an embodiment of the present invention.

FIGS. 2A and 2B are views showing an injection molding die according to another embodiment of the present invention, wherein FIG. 2A is an explanatory view of a transfer mode by an electroforming method, and FIG. It is sectional drawing.

FIG. 3 is a diagram showing another embodiment of the temperature control circuit of the mold.

[Description of Signs] 1 Fixed block 1a recess 2 Movable block 2a recess 3 Dam block 4 Guide block 5a, 5b Mold insert 6a, 6b Glass plate 7a, 7b Backing member 8 Sprue 9 Runner 10 Gate 11 Glass Plate 12a, 12b Electroformed member 13a, 13b Mold insert 14a, 14b Backing member 15 Independent temperature control circuit for heating 16 Independent temperature control circuit for cooling 17 Insulated plate

Claims (11)

[Claims] 1. A mold for injection molding, wherein a wall surface of a cavity is formed of a thin plate having a dense surface, and a backing member for supporting the thin plate is provided on a back side of the thin plate. 2. The injection mold according to claim 1, wherein the thin plate is a flat glass plate of float glass or polished glass or a formed glass plate. 3. The injection mold according to claim 1, wherein the thin plate is made of any one of polycarbonate, acrylic, and SMC. 4. The injection molding die according to claim 1, wherein the thin plate is an electroformed member formed by transferring an electroformed method from a glass plate processed into a predetermined shape. 5. The injection mold according to claim 1, wherein the thin plate is a metal plate formed by using a forming die whose cavity wall surface is formed of a glass plate. 6. The injection mold according to claim 1, wherein a coating layer for facilitating mold release is provided on a surface of said thin plate. 7. The injection mold according to claim 1, wherein the backing member is made of epoxy resin or cement. 8. The injection mold according to claim 1, further comprising a local heating means for locally heating the surface of said thin plate. 9. The injection mold according to claim 8, wherein the local heating means heats the surface of the thin plate by coating the surface of the thin plate with a current-carrying heating material. 10. The injection mold according to claim 8, wherein the local heating means heats the surface of the thin plate by embedding a sheet heater on the back surface side of the thin plate. 11. The injection molding die according to claim 8, wherein the local heating means heats the surface of the thin plate by embedding a copper pipe on the back surface side of the thin plate.