JPH0635134B2 - Cavity forming mold member and manufacturing method thereof - Google Patents

Description

The present invention relates to a mold member for forming a cavity of a synthetic resin molding mold and a method for manufacturing the same, and the mold member manufactured by the invention is a thermoplastic resin. In addition to injection molding and blow molding, it can be used for stamping molding, which is a type of compression molding, and for thermosetting resins, it is used for injection molding, compression molding, transfer molding, and other mold cavity forming die members. Available as

[Prior Art] Conventionally, a mold member for forming a cavity of a mold for synthetic resin molding has generally been required to have a dimensional accuracy and durability and a surface having a gloss finish close to a mirror surface. The processing of such die members requires high-grade steel materials, skilled techniques, expensive and high-grade processing equipment, and long processing days, which makes it possible to shorten the delivery time and lower the price of die manufacturing. It has been hindered.

On the other hand, in order to transfer the fine luster of the mold surface and the like and to obtain a molded product without defects such as silver strips, cloudiness and welds, a sufficient filling pressure for the resin in the mold cavity has been achieved compared to the past. It has been known that it is desirable to keep the surface temperature of the cavity forming mold member close to the melting temperature of the resin until the temperature is transmitted. However, it is not easy to realize this with reasonable productivity. For example, in injection molding of thermoplastic resin, the mold cavity forming mold member is heated to a high temperature during injection and cooled after completion of injection. To do.

A resin layer having a low thermal conductivity is provided on the surface of the cavity forming mold member.

However, in the former case, the equipment for heating and cooling is expensive and the molding cycle is significantly prolonged, and in the latter case, the resin layer deteriorates rapidly due to heat and pressure, resulting in poor durability. It has drawbacks such as being extremely low, and has not been generalized in any way.

[Problems to be Solved by the Invention] In order to solve the problems in the conventional technology as described above, the present invention (1) does not require highly skilled technology, and can be delivered in a short time and at low cost, with heat resistance, wear resistance, etc. (2) And this mold cavity forming mold member suppresses defects of molded products such as silver strips, cloudiness, welds, etc. It was developed with an emphasis on being able to supply molded products with efficiency.

That is, in the present invention, the surface of the cavity forming mold member is constituted by a material layer having high heat resistance, wear resistance, etc. and low thermal conductivity (hereinafter referred to as a heat insulating layer), and as described in the above item (2). In the present invention, it is almost impossible to manufacture the mold member for forming a cavity having such a heat insulating layer easily and with high precision in an attempt to satisfy the purpose, and therefore, in the present invention, such a cavity is used. The purpose is also to develop a method for manufacturing a forming die member.

[Means for Solving the Problems] Next, the present invention will be described.

A master is created using a material that is easy to manufacture by a method such as cutting, casting or casting, and polishing, and is easily removed by a method such as melting, melting, or drawing, and then heat and resistance are applied to this surface. After forming a heat-insulating layer with a material with excellent wear resistance and low thermal conductivity, and further forming a metal part with excellent thermal conductivity on the outside, heat and resistance to the inner surface by removing the master. This makes it possible to manufacture a mold member for forming a cavity of a mold having an abradable heat insulating layer.

As the heat-insulating and heat-insulating layer used in the present invention, an inorganic glass layer and then a fine ceramic layer are formed on the surface, or a metal plating layer is further formed on these surfaces. It is preferably a layer.

[Operation] The cavity forming die member manufactured according to the present invention has the metal portion on the outside thereof processed into a predetermined size, and then, in the thermoplastic resin, as a cavity forming die portion of the injection and blow molding die, Further, the thermosetting resin is inserted into the mold as a cavity forming mold part of a mold for injection, compression and transfer molding, and used for molding.

The cavity forming mold member of the present invention has a heat-resistant surface,
Since it has a so-called heat-insulating layer, which has excellent wear resistance and low thermal conductivity, the formation of the solidified or hardened layer in the filling process is delayed as described above, and therefore the surface of the molded product is It faithfully transfers the pattern and gloss on the surface of the mold for cavity formation, and has the effect of significantly reducing the appearance defects that occur during molding.

Further, more preferably, in the case of a thermoplastic resin, by irradiating a high-energy ray such as a halogen lamp or by irradiating with hot air, and in the case of a thermosetting resin, by irradiating with cold air, the surface of the cavity forming mold part is temporarily exposed. The temperature can be set to a high temperature or a low temperature, and in such a case, the effect of the heat insulating layer described above can be more remarkable.

Further, in the cavity forming mold member of the present invention, due to its heat insulating layer, it is possible to prolong the cooling time of the molded product in the thermoplastic resin and prolong the curing time in the thermosetting resin, In practice, the heat insulating layer allows the mold temperature to be set lower in the thermoplastic resin and higher in the thermosetting resin, and the molding cycle usually tends to be shortened.

[Embodiment] Next, an embodiment of the present invention will be described with reference to the drawings.

First, the embodiment shown in FIG. 1 will be described as the embodiment (1). FIG. 1 is a process diagram showing a manufacturing process sequence of a cavity forming mold member. For example, a master 1 is made of a low melting point metal or a material that is soluble in an acid or an alkali, and an inorganic glass layer 2 is first formed on the surface of the master 1, and then a fine ceramic layer 3 is formed, and then a metal portion 4 is further formed. And melt the master 1 by heating, or dissolve it with an acid or an alkali to remove it, and form a mold member for forming a cavity of a synthetic resin molding mold having a layer with low thermal conductivity on the surface. It is to be produced.

FIG. 2 shows a use state of the embodiment of the present invention,
In the drawing, 5 indicates a core and 6 indicates a synthetic resin.

Of course, it is also possible to form a layer having low heat conduction only by the fine ceramic layer 3, but in this case, the surface becomes somewhat rough, and when the heat insulating layer is constituted by only the inorganic glass layer 2, this layer is formed. 2 itself easily cracks,
Further, the joining force with the metal portion 4 is low.

The fine ceramic used in the present invention is excellent in heat resistance and heat insulation and has high impact resistance, and the surface in contact with the metal part 4 is particularly rough, so that it produces a high bonding force.

Furthermore, fine ceramics can penetrate into the inorganic glass layer 2 during thermal spraying and strongly bond with the glass layer 2.
It also has the effect of strengthening the glass layer 2.

Next, the example (2) will be described. Before forming the inorganic glass layer 2 of the example (1), a metal plating layer 7 is formed on the master 1, and then the same as in the example (1). The inorganic glass layer 2, the fine ceramic layer 3, and the metal portion 4 are formed on the inner surface, and the master 1 is finally pulled out.

The cross section of the cavity forming mold member produced in Example (2) is shown in FIG. 4 together with its partially enlarged view.

In this case, the master 1 is easy to produce, has a low adhesion to the plating layer 7, and after the cavity forming mold member is formed, the plating layer 7 is pulled out while being bonded to the inorganic glass layer 2. Therefore, brass and glass products were used as the master 1 in the present invention. As the material for plating, in the present embodiment (2), a nickel-based plating bath which is easy to perform electroless plating and electrolytic plating was used.

As the material for the above master 1, aluminum and its alloys, low melting point alloys, brass, glass products, etc. can be used. Among these, when aluminum materials and low melting point alloys are used, the surface of Is the inorganic glass layer 2
Is easily formed and can be advantageously used in the two-layer structure of the embodiment (1). When brass and glass products are used as the master 1, the plated layer 7 is easy to form, which is suitable for the three-layer structure of the embodiment (2). In addition, the material for the master is selected in consideration of the type and material of the heat insulating layer, the difficulty of manufacturing the master, the method of removing the master in the final step, and the like.

Further, as the heat insulating layer, first, in the case of plating, chemical plating is performed if necessary, and then electrolytic plating is performed. The plating material can be nickel, chromium, or various composite platings.

As the inorganic glass, either water glass or glass enamel is selected according to the purpose. The former water glass can be baked at a low temperature and a thin layer can be easily obtained, and the glass enamel of the latter requires baking at a slightly high temperature, but it has better heat resistance and abrasion resistance than water glass. These inorganic glasses are coated by ordinary spraying, brushing or dipping, and baked at a processing temperature suitable for each. There are various fine ceramics such as alumina, silicon carbide, silicon nitride and zirconia, and their composites can be used for the purpose of the present invention. Since all of these fine ceramics have high melting points, it is advantageous to spray them with a plasma spraying device.

The metal part formed on the outer side of the heat insulating layer can be almost any metal material as long as it is a metal material. However, it is preferable that the mold, thermal spraying and the like are easy and the thermal conductivity, heat resistance and strength are excellent to some extent.

Regarding the removal of the master die, in the case where the surface of the cavity forming die member is composed of the inorganic glass layer, the master die is removed by melting or melting. If the surface of the master die is a plated layer, the master die can be pulled out as it is.

[Advantages of the Invention] The present invention has many advantages over the following conventional mold cavity forming mold member and its processing method.

Since the master is manufactured by a method that is easy to process and the cavity forming mold is created by reversing the master, it requires more advanced skill and equipment than the conventional direct forming of the cavity forming mold. It is not necessary, and the number of processing days is also shortened, which leads to shorter delivery time and lower price of the mold.

The mold cavity-forming mold member obtained by the present invention faithfully transfers the accuracy of the master. Therefore, if only the master is processed with high gloss or high accuracy, the cavity with excellent gloss and accuracy can be easily obtained. A molding die member is obtained.

The cavity forming mold member obtained by the present invention,
Since its surface is composed of a material layer having excellent heat resistance and wear resistance, its durability is excellent.

The cavity forming mold member obtained by the present invention,
It is heat and abrasion resistant, and it is easy to obtain specular gloss.
Moreover, since it has a heat insulating layer, the molten resin does not easily solidify or harden in the initial stage of molding, and therefore, the gloss or pattern of the cavity forming mold member surface is faithfully transferred, and Molding defects such as silver strips, welds, and cloudiness are unlikely to appear.

Conventionally, there has been a method of increasing the mold temperature in a thermoplastic resin and decreasing the mold temperature in a thermosetting resin for the above purpose, but in any of these cases, the molding cycle is remarkably prolonged. The result was,
In the cavity forming mold member of the present invention, not only can the conventional molding cycle be maintained as described above,
Rather, it can be shortened.

[Brief description of drawings]

FIG. 1 is a process drawing of an embodiment of the present invention, FIG. 2 is a sectional view showing the same use state, and FIG. 3 is an enlarged view of a portion A of FIG.
FIG. 4 is a cross-sectional view showing a second embodiment of the present invention, the main part of which is enlarged. 1 ... Master 2 ... Inorganic glass 3 ... Fine ceramic layer 4 ... Metal part 5 ... Core 6 ... Synthetic resin 7 ... Metal plating layer

Claims (4)

[Claims] 1. A mold used for molding a synthetic resin,
A cavity forming mold member having an inorganic glass layer as a surface layer and a fine ceramic layer formed on the surface to form a two-layer structure having low thermal conductivity and having these on the surface. 2. A cavity forming mold member, wherein a metal plating layer is formed on the surface of the layer having low thermal conductivity according to claim 1. 3. The method for manufacturing a cavity forming mold member according to claim 1, wherein an inorganic glass layer is formed on the surface of the master.
Next, a mold having a low thermal conductivity composed of a fine ceramic layer is formed, and a metal part having excellent thermal conductivity is further formed on the outer side of the layer, and then the master is removed. A method of manufacturing a member. 4. The method of manufacturing a cavity forming mold member according to claim 3, wherein a metal plating layer is formed on the surface of the master.