JPH0724652A - Machining of forming die - Google Patents

Abstract

PURPOSE:To machine a forming die having a complex pattern and a fine pattern even in the case of using hard metal as a forming die material. CONSTITUTION:Firstly, a reversed die 11 having a reversal pattern 10 of a die pattern 3 to mold a Fresnel lens is manufactured. Thereafter, with this reversal die 11 as an electrode, a lower die 6 made of a hard metal material is electric discharge machined, and the lower die 6 is manufacture. A forming die 4 is formed by combining this lower mold 6 and upper die 5 manufactured by cutting and machining a hard metal material with each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for processing a molding die. In particular, it relates to a method for producing a molding die having a complicated molding pattern.

[0002]

2. Description of the Related Art Molding methods include molding methods such as compression molding, transfer molding and injection molding. In these molding methods, when a fine pattern is projected on the surface of a molded product, it is necessary to form a corresponding fine molding pattern on the cavity surface of the molding die used for the molding process.

Consider, for example, the case where a Fresnel element 1 having a complicated structure and having a Fresnel lens 2 which requires high precision is formed. FIG. 3 is a perspective view showing a typical Fresnel element 1. FIG. 4 is a sectional view showing a molding pattern 3 for molding the Fresnel lens 2 of the Fresnel element 1. When the Fresnel element 1 is manufactured by molding, the molding pattern 3 corresponding to the lens pattern of the Fresnel lens 2 needs to be directly cut on the cavity surface of the molding die 4. Further, a molding pattern 3 used when the Fresnel element 1 having a size of several mm is manufactured by molding.
Is composed of very fine irregularities as shown in FIG. 4, and this lens pattern requires very high accuracy.

However, it is very difficult to accurately form such a minute and complicated forming pattern of several tens of microns on a hard metal material used in a conventional forming die by cutting. On the other hand, if a soft metal material is used as the mold material, such a fine molding pattern can be processed into a molding mold with high accuracy, but in this case, the wear of the molding mold due to the material resin is severe,
Stable molded products cannot be obtained. Therefore, it is difficult to manufacture a molded product having a complicated pattern such as a Fresnel lens by injection molding or the like.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the drawbacks of the above-mentioned conventional examples, and its object is to obtain a complicated structure even when a hard metal is used as a mold material. It is an object of the present invention to provide a method for processing a molding die that can manufacture a molding die having a pattern or a fine pattern.

[0006]

A method of processing a molding die according to the present invention is to manufacture an inverse mold having an inversion pattern of at least a part of a molding pattern provided in a cavity of the molding die, and perform the inverse mold. It is characterized in that a cavity is machined in a molding die by performing electric discharge machining or electrolytic machining as an electrode.

[0007]

In the processing method of the molding die according to the present invention,
Since the cavity is processed by performing electrical discharge machining or electrolytic processing on the mold material using the reverse mold, it is possible to easily and accurately manufacture complicated molding patterns on the molding mold made of hard metal. . Therefore, it is possible to manufacture a molding die that has a complicated molding pattern, is resistant to wear, and at least the entire cavity portion is made of hard metal.

[0008]

FIG. 2 is a cross-sectional view of a molding die 4 according to an embodiment of the present invention used when manufacturing the Fresnel element 1 as shown in FIG. This mold 4
Is divided into an upper die 5 and a lower die 6, and an upper die 5 and a lower die 6
All are made of a hard metal material such as stainless steel. A flat molding pattern 7 for molding the outer surface shape of the Fresnel element 1 is formed on the mold opening surface of the upper mold 5. The Fresnel element 1 is provided on the mold opening surface of the lower mold 6.
A flat molding pattern 8 for molding the outer surface shape and a complicated molding pattern 3 for molding the Fresnel lens 2
And are formed. A cavity 9 surrounded by the molding patterns 3, 7, and 8 is formed between the upper mold 5 and the lower mold 6.

When manufacturing the Fresnel element 1 using this molding die 4, for example, an element (not shown) such as a light emitting element or a light receiving element is set in the cavity 9 and resin is injected into the cavity 9. Then, when the Fresnel element 1 is injection-molded, the element is insert-molded inside and the Fresnel lens 2 is molded on the surface by the complicated molding pattern 3.

1A, 1B and 1C show the molding die 4 described above.
FIG. 6 is an explanatory view showing a manufacturing method of. In order to manufacture the molding die 4, first, as shown in FIG. 1A, a reverse mold 11 having a reversal pattern 10 in which irregularities are reversed from the molding patterns 3 and 8 of the lower mold 6 is manufactured. That is, the reverse pattern 10 formed on the reverse mold 11 has the same shape as the surface on one side of the Fresnel element 1. Therefore, it is easier to design and manufacture the reversal pattern 10 having the same shape as the Fresnel element 1 on the reverse mold 11 than to design and manufacture the molding patterns 3 and 8 in which the shape of the Fresnel element 1 is reversed on the lower mold 6. The reverse mold 11 may be manufactured by cutting a soft metal material such as aluminum or copper-based metal, or may be formed by forming a metal coating on the surface of the ceramic core material having the inverted pattern 10. Good. When the reverse mold 11 is manufactured, the lower mold 6 made of a hard metal material is subjected to electric discharge machining or electrolytic machining using the reverse mold 11 as an electrode to form a reverse pattern 10 of the reverse mold 11 as shown in FIG. 1B. The molding patterns 3 and 8 are manufactured on the lower mold 6 by transferring the molding patterns 3 and 8 to the lower mold 6. On the other hand, the upper die 5 made of a hard metal material is cut to form a molding pattern 7 on the upper die 5. By combining the upper mold 5 and the lower mold 6 thus manufactured, the molding die 4 as shown in FIG. 2 is completed.

As described above, the cavity 9 is formed by using the reverse mold 11.
By producing the part of the complicated molding pattern 3 of
A complicated and fine pattern can be easily manufactured even on the molding die 4 made of a hard metal material. Moreover, since a plurality of molding dies 4 can be manufactured by one reverse mold 11, the manufacturing efficiency of the molding dies 4 can be improved. Further, if the reverse die 11 is manufactured by coating the surface of the ceramic core material with the metal coating as described above, when the reverse die 11 is worn by electric discharge machining or the like, the metal coating is re-coated on the surface of the core material. It can be used repeatedly by coating.

Further, the applicant of the present invention has disclosed that the fine pattern portion is a partial metal mold made of a soft metal, and the partial metal mold is fitted into a hole of a mold body made of a hard metal so as to be integrated (special feature). Japanese Patent Application No. 4-289486). In the molding die filed earlier, since a partial mold of soft metal is used, wear during molding may occur, and stable molding may not be continued. Since it can be formed of a hard metal material, wear of the molding die does not occur, and stable molding can be performed. Further, in the molding die filed earlier, since the partial die is fitted into the die body to assemble, strict dimensional accuracy is required so that no gap is created. However, according to the present invention, such a portion Since no mold is used, it is possible to manufacture a molding mold without having to worry about the dimensional tolerances of tight fitting.
The molding die assembly process is also unnecessary.

In FIGS. 1A, 1B and 1C, the lower mold 6 is manufactured only by electric discharge machining or electrolytic machining using the reverse mold 11, but it may be used in combination with cutting. That is, after the whole is processed by cutting to form the cavity 9 in which the molding pattern 3 for molding the Fresnel lens 2 is not formed, a reverse mold 11 is used in a part of the smooth cavity 9 for electric discharge machining. Alternatively, only the complicated molding pattern 3 for molding the Fresnel lens 2 may be processed by electrolytic processing.

[0014]

According to the method for processing a molding die according to the present invention, a molding die made of a hard metal having a complicated molding pattern and resistant to abrasion can be manufactured accurately and stably. A molded product having a complicated pattern such as a Fresnel lens can be molded by injection molding or the like, which enables stable mass production.

[Brief description of drawings]

1 (a), (b) and (c) are explanatory views showing a method for processing a molding die according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a molding die manufactured by the above processing method.

FIG. 3 is a perspective view of a Fresnel element.

FIG. 4 is a partially cutaway sectional view showing a molding pattern for molding a Fresnel lens of a Fresnel element.

[Explanation of symbols]

 1 Fresnel element 2 Fresnel lens 3 Molding pattern 4 Molding die 5 Upper mold 6 Lower mold 7,8 Molding pattern 9 Cavity 10 Reverse pattern 11 Reverse mold

Claims (1)

[Claims] 1. A cavity is formed in a molding die by manufacturing an inverse mold having an inversion pattern of at least a part of a molding pattern provided in a cavity of the molding die and performing electric discharge machining or electrolytic machining using the inverse mold as an electrode. A method for processing a molding die, which comprises: