JPH04101813A - Metallic material for plastic forming mold and forming mold - Google Patents

Abstract

PURPOSE:To improve the durability of molds and shorten the forming cycle by a method wherein highly thermally conductive metal is used as base material and high strength metal layer is metallurgically joined to the surface of the base material. CONSTITUTION:As the highly thermally conductive metal to be used for the base material of the metallic material for forming mold, aluminum, aluminum alloy or the like is used. As the high strength metal metallurgically joined to the surface of the base material, metal having high strength and wear resistance such as steel, stainless steel or the like is used. The metallurgical joining is to join two metals by bringing them close to each other within the region, in which interatomic attraction acts, and normally performed by a pressure welding means such as friction welding, explosion welding, roll welding, vacuum diffusion or the like. The main body parts 3 and the bottom parts 4 of split molds 2 for blow-molding a plastic bottle, for example, are made of aluminum alloy. At the tip edges of the pinch-off parts 5 at the bottom parts 4, mechanical structural carbon steel layers 6 are metallurgically joined to the surface of the base material by explosion welding. By using said molds, the cooling rate becomes higher and consequently the forming cycle can be shortened. Further, no non-conforming part due to temperature ununiformity at cooling develops in the formed article. At the same time, the breakage of the pinch-off parts is hard to occur.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a metal material used in a plastic mold and a mold using the metal material.

[Problem to be solved by the invention]

There are various molding methods such as injection molding and blow molding for molding plastics, but molds are often used to mold plastics into desired shapes. In general, molds used in injection or blow molding must have sufficient strength and hardness, be durable, have good thermal conductivity, and be able to cool the molded product quickly and make it easy to remove the molded product. Conditions such as ease of use were required. That is, high-strength metal materials are required in terms of durability, precision, etc. of molds, and metal materials with high thermal conductivity are required in order to speed up molding cycles and increase productivity. In general, molds are required to have the ability to cool the molded product at the same time as molding, and the cooling time is said to account for 50 to 60% of the molding cycle, and the cooling rate of the mold is a condition that determines the molding cycle. There is.

However, conventional molding molds use metal materials such as steel, stainless steel, copper alloy, aluminum alloy, zinc alloy, etc., and generally, molds are made using solid materials or
Alternatively, the mold was divided into multiple parts and the parts made from multiple materials were combined to create the mold. Therefore, conventionally, it has been difficult to simultaneously provide the high strength of steel and the like and the high thermal conductivity of aluminum and the like to one mold or one part.

For example, if the blow molding mold is made of aluminum alloy, the cooling rate will be improved and the molding cycle will be shortened, but the pinch-off part (the cut-off part of the parison tail) will wear out severely, and other parts will need to be replaced. Frequency increases.

This necessitates replacement of the mold, interrupting continuous operation and impairing efficiency.

Also, if the mold is divided and the pinch-off part is made of stainless steel or steel that is different from the main body, and the mold is assembled using these parts, the thermal conductivity of the metal materials of the mold body and the pinch-off part will be different. Therefore, there is a significant difference in the cooling rate of plastic molded products, which can cause uneven structures such as streak-like patterns to occur at the boundaries, and the molding cycle is rate-limited by the cooling rate of stainless steel and steel parts, resulting in shorter cycle times. It had the disadvantage of being long.

This invention was made by focusing on problems such as the above revision. The objective is to develop metal materials for plastic molds that have high strength and high thermal conductivity, improve the durability of molds, shorten molding cycles, and prevent defects in molded products due to uneven cooling. We propose molding molds.

[Means to solve the problem]

The metal material for plastic molds according to the invention (1) is characterized in that it is made of a highly thermally conductive metal as a base material, and a high-strength metal layer is metallurgically bonded to the surface thereof. In the plastic molding mold according to the invention (2), the member of the pinch-off part is made of a metal material with a high thermal conductivity metal as a base material and a high-strength metal layer metallurgically bonded to the surface thereof, and the tip edge of the pinch-off part is It is characterized by being made of the high-strength metal layer.

Highly thermally conductive metals that serve as base materials for the metal materials of this invention include aluminum, aluminum alloys, copper, copper alloys, etc., and high-strength metals include general structural rolled steel, mechanical structural carbon steel, structural alloy steel, and carbon steel. Steel such as tool steel and bearing steel, stainless steel, and other metals with high strength and wear resistance. In particular, aluminum and aluminum alloys are suitable for use as base materials because they are lightweight, have excellent workability, and have high thermal conductivity. The thickness of the high-strength metal layer such as steel or stainless steel is 0.5 to 10
mm, and is often used in the range of 1 to 5 mm.

Metallurgical joining as used in this invention refers to joining two metals close to the area where atomic attraction is applied, and is usually joined by pressure welding methods such as friction welding, explosive welding, roll welding, and direct air diffusion. . In addition, when it is difficult to join two different metals directly, it can be used as an intermediate material.
For example, pure aluminum, titanium, nickel, pure iron, etc. can be used for bonding.

〔Example〕

The following will explain the embodiments shown in the drawings. Figure 1-2 shows a mold 1 for blow molding a plastic bottle from a parison. This mold 1 consists of two symmetrical split molds 2.
The mold is divided into two parts, and each divided mold 2 is made up of two parts, a main body part 3 and a bottom part 4, which are integrally assembled. Both the main body part 3 and the bottom part 4 are made of aluminum alloy, and a mechanical structural carbon steel layer 6 with a thickness of 3 am is metallurgically applied to the base material surface by explosive crimping on the tip edge of the pinch-off part 5 of the bottom part 4. It is joined.

This mold cools the molded product quickly, shortens the molding cycle, eliminates malfunctions in the molded product due to temperature unevenness during cooling, and prevents damage to the pinch-off area, ensuring long-term durability. can.

[Action and effect of the invention]

This metal material has a high-strength metal layer metallurgically bonded to the surface of a highly thermally conductive metal base material, and the high thermal conductivity of the base material is expressed as it is, so a mold using this material can form a molded product. The cooling rate is fast and the molding cycle can be shortened. At the same time, it is possible to prevent the occurrence of defects such as a heterogeneous structure caused by uneven cooling that occurs when dissimilar metal materials are used in combination. Furthermore, the durability of the mold can be improved due to the high wear resistance of the high-strength metal layer on the surface.

Using this metal material for the pinch-off part of a blow molding mold and placing a high-strength metal layer on the tip edge can shorten the molding cycle, improve mold durability, and prevent molded product defects due to uneven cooling. can be achieved at the same time.

[Brief explanation of the drawing]

1 and 2 are an overall perspective view and a sectional view of the bottom of the blow molding die of the example. 1...Mold, 2...Divided mold, 3...Main body, 4
...bottom, 5...pinch-off portion, 6...carbon-copper layer for mechanical structure.

Claims (2)

[Claims] (1) A metal material for plastic molds, characterized in that it is made of a highly thermally conductive metal as a base material, and a high-strength metal layer is metallurgically bonded to the surface of the base material. (2) The member of the pinch-off part is made of a metal material in which a high-thermal conductive metal is used as a base material and a high-strength metal layer is metallurgically bonded to the surface thereof, and the tip edge of the pinch-off part is made of the high-strength metal layer. Plastic molding mold.