JPS62252638A - Production of molding tool - Google Patents

Abstract

PURPOSE:To reduce the production cost and to improve impact resistance by pouring the melt of a tool steel into a tool molding part, pouring the melt of a cast iron near the same to obtain the partial mold of the molding part, then embedding the partial mold into the other casting mold and pouring the melt of the cast iron therein. CONSTITUTION:The melt of the tool steel compsn. is poured from a sprue 8 of the casting mold 7 into a tool steel part 9 and the melt of the spheroidal graphite cast iron compsn. is poured from the sprue 8 of the casting mold 8 into a cast iron part 10 at the point of the time when the prescribed time elapses to fill the mold cavity part. The partial mold 11 of the molding part consisting of the tool steel part 9 and the cast iron part 10 obtd. in such a manner is embedded into the other casting mold 12. The melt having the same compsn. as the compsn. of the spheroidal graphite cast iron is poured from a sprue 13 into the mold to fill the mold cavity part. The manufactured molding tool is heated to a prescribed temp. and is subjected to furnace cooling after holding for the prescribed time. The service life is thereby extended and the period and production cost are reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for manufacturing a forming die suitable for use in press dies, drawing dies, punching dies, and the like.

[Conventional technology]

Forming dies require strength and wear resistance, so tool steel is widely used, but the material costs are high, so a method of placing tool steel on the forming surface and its vicinity and fixing it with bolts, Alternatively, a method has been implemented in which a member equivalent to tool steel is welded overlay on the forming surface and its vicinity.

[Problem that the invention seeks to solve]

In the former case, the manufacturing cost increases because the part to which the tool steel is attached must be machined, and problems remain, such as bolts loosening during use.

In the latter case, large molds not only increase the number of welding steps, but also include factors that impede cost reduction, such as distortion caused by heat effects and the need for modification of the molding surface, which is by no means a desirable structure. .

In order to solve these problems, we developed a method to obtain a composite mold by injecting molten metal with a tool steel composition into the forming part of the mold, and then injecting molten metal with a cast iron composition into other parts. has been done.

However, especially in cutting dies, tool steel is often used for the corner portions of the molded portions 1 that serve as blades, as shown in FIG.

In this case, if the molten metal with the composition of tool steel is injected using the mold 2 shown in Figure 2, the expensive molten metal will flow into areas other than the forming part, and even if the mold 3 shown in Figure 3 is used, the same problem will occur. Incur consequences. Therefore, if a mold 4 as shown in FIG. 4 is used, molten metal having a tool steel composition can be injected only into the corners, but a core 5 is required, which significantly impairs workability.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a molding die that overcomes the above-mentioned drawbacks of the prior art, increases the service life, and reduces manufacturing time and manufacturing costs.

[Means for solving problems]

In the method for manufacturing a forming die of the present invention, when manufacturing a forming die using a casting mold, first, a molten metal having a tool steel composition is injected into the mold cavity of a forming part of the die, and the molten metal is injected into the vicinity of the forming part. The method is characterized in that after a molded partial mold is obtained by injecting a molten metal having a cast iron composition, the molded partial mold is embedded in another mold and the molten metal having a cast iron composition is poured and cast.

〔Example〕

Embodiments of the method for manufacturing a molding die according to the present invention will be described in more detail below with reference to the drawings.

Figure 6.7 is a cross-sectional view of a mold for implementing the invention.

(1) Molten metal having a tool steel composition consisting of mold iron, unavoidable impurities, and the following components was poured into the tool steel section 9 from the sprue 8 of the mold 7. The injection temperature at that time was 1540°C.

(wt%) About 30 seconds after pouring the molten metal with the above tool steel composition, the molten metal with the composition of spheroidal graphite cast iron (JIS G5502 FCD60), which consists of iron, unavoidable impurities, and the following components, is poured into the sprue of mold 7. 8 into the cast iron part 10 to fill the mold cavity. The injection temperature at that time was 1390°C.

The forming part mold 11 consisting of the tool steel part 9 and cast iron part 10 thus obtained was buried in another mold 12, and molten metal having the same composition as the spheroidal graphite cast iron was injected from the sprue 13 to fill the mold cavity.

(2) Heat Treatment The produced molding die was heated to 780°C, held for 4 hours, and then cooled in a furnace.

(3) Mechanical properties A JIS No. 4 tensile test piece shown in FIG. 8 was created from the mold. At this time, processing was performed so that the boundary between the tool steel section 14 and the cast iron section 15 was located at the center 16 of the parallel section. The tensile test results showed a tensile strength of 63.5 to 65.9 kgf/Ryu 2, and the fracture locations were all cast iron parts, not boundary parts.

(4) The hardness distribution (Rockwell B scale) near the hardness boundary is shown in FIG.

(5) Structure As mentioned above, since the molten metal having a cast iron composition is injected into the forming part mold 11 immediately after the molten metal having a tool steel composition has solidified, there is a risk that the tool steel part 9 and the cast iron 10 may completely weld and separate. Not at all.

Furthermore, when the forming part mold 11 is buried in the mold 12 and cast, molten metal having the same composition as the cast iron part 10 is injected, so that it is completely welded, and the boundary part is not formed, as is clear from the micrograph shown in Fig. 10. , tool steel and cast iron are completely fused and no abnormal structure is observed.

Although spheroidal graphite cast iron was used as the cast iron material in this embodiment, it is of course possible to use flake graphite cast iron, vermicular graphite cast iron, or the like.

〔Effect of the invention〕

As is clear from the above description, the method for manufacturing a molding die of the present invention has many excellent effects such as reduced manufacturing costs, improved impact resistance, and increased service life.

4. Brief explanation of the drawings ' Figure 1 is a front view of the mold, Figure 2 is a side view, Figure 3.4.5 is a sectional view of a conventional mold, and Figure 6.7 is a mold of the present invention. FIG. 8 is a plan view of a test piece, FIG. 9 is a hardness distribution diagram, and FIG. 10 is a metallographic microstructure photograph.

14: Tool steel part, 15: Cast iron part, 11: Molding part mold.

Claims (1)

[Claims] When manufacturing a forming die using a casting mold, first, a molten metal having a tool steel composition is injected into the mold cavity of the forming part of the mold, and a molten metal having a cast iron composition is injected into the vicinity of the forming part to form the forming part. 1. A method for manufacturing a mold having an integral casting structure, which comprises: obtaining a mold, embedding the partial mold in another mold, and injecting molten metal having a cast iron composition to fill the mold.