KR101053701B1 - Manufacturing method of mold for glass molding - Google Patents

Abstract

At least one of 0.3 wt% or more and 2.7 wt% or less, chromium 13 wt% or less, molybdenum 0.5 wt% or more and 3 wt% or less, vanadium 0.1 wt% or more and 5 wt% or less, tungsten 1 wt% or more and 7 wt% or less. A substrate is produced by quenching a steel material to which a satisfactory additive is added, and tempering at 400 ° C. or higher and 650 ° C. or lower, and a surface coating layer made of an amorphous Ni-P alloy is formed on the surface of the substrate. by carrying out a heat treatment, change the surface coating layer to the process organization of Ni and Ni ₃ P. This prevents cracking in the surface coating layer at the molding temperature and prevents plastic deformation of the mold, thereby maintaining the shape of the mold with high accuracy.

Tempering, quenching, stainless steel, austenitic, martensite

Description

Manufacturing method of mold for glass molding {METHOD FOR PRODUCING MOLD FOR GLASS MOLDING}

TECHNICAL FIELD This invention relates to the manufacturing method of the metal mold | die for glass shaping | molding which requires precise processing, and it is especially related to being able to maintain the shape of a metal mold with high precision.

In the field of plastic molding, the precision processing technology of a molding die is established, and mass production of optical elements having a fine shape such as a diffraction grating is realized. In this case, manufacture of a metal mold | die is performed by performing electroless Ni-P plating on the surface of the base material which consists of stainless steel, and then precision-processing this plating layer with a diamond bite.

However, when such a mold is applied to glass molding, a problem occurs that a crack occurs in the electroless Ni-P plating layer. This phenomenon is caused by the molding temperature. That is, the Ni-P plated layer has an amorphous (amorphous) structure in the plated state, but when heated to about 270 ° C. or more, crystallization starts, at which time a volume shrinkage occurs in the plated layer, and a tensile stress acts to crack the plated layer. Occurs.

As a countermeasure against this problem, a substrate having a coefficient of thermal expansion of 10 × 10 ⁻⁶ to 16 × 10 ⁻⁶ (K ⁻¹ ) is selected and heat-treated at 400 to 500 ° C. after plating. However, even if the thermal expansion coefficient of the substrate is matched with the Ni-P plating layer, since the volume shrinkage accompanying crystallization occurs only in the plating layer during heat treatment, a large tensile stress acts on the plating layer and cracks may occur (for example, See Japanese Patent Application Laid-Open No. 11-157852.

In addition, when the temperature is high during use of the mold, plastic deformation occurs in the mold, and there is a problem that the shape of the mold cannot be maintained with high precision.

The present invention provides a glass molding die which can prevent cracks in the surface coating layer at the molding temperature and prevent plastic deformation of the mold, thereby maintaining the shape of the mold with high accuracy and increasing its lifespan. It aims at providing the manufacturing method of the.

In order to solve the said subject and achieve the objective, the manufacturing method of the metal mold | die for glass molding of this invention is comprised as follows.

At least one of 0.3 wt% or more and 2.7 wt% or less, chromium 13 wt% or less, molybdenum 0.5 wt% or more and 3 wt% or less, vanadium 0.1 wt% or more and 5 wt% or less, tungsten 1 wt% or more and 7 wt% or less. The substrate is formed by quenching the steel material to which a satisfactory additive has been applied, and tempering at 400 ° C. or more and 650 ° C. or less, and a surface coating layer made of an amorphous Ni-P alloy is formed on the surface of the substrate, and is heated thereon. by carrying out the process, change the surface coating layer to the process organization of Ni and Ni ₃ P.

At least one of 0.3 wt% or more and 2.7 wt% or less, chromium 13 wt% or less, molybdenum 0.5 wt% or more and 3 wt% or less, vanadium 0.1 wt% or more and 5 wt% or less, tungsten 1 wt% or more and 7 wt% or less. By quenching the steel material to which the satisfactory additives were added, the substrate was formed by sub-zero treatment, and the surface coating layer made of amorphous Ni-P alloy was formed on the surface of the substrate, and this was subjected to heat treatment. The surface coating layer is replaced with a process structure of Ni and Ni ₃ P.

BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram which shows the outline | summary of the manufacturing method of the metal mold | die for glass molding which concerns on one Embodiment of this invention.

BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram which shows the outline | summary of the manufacturing process of the metal mold | die for glass molding which concerns on one Embodiment of this invention. The manufacturing of the glass molding die is performed in the following steps.

Further, the base material is 0.3 wt% or more, 2.7 wt% or less, chromium 13 wt% or less, molybdenum 0.5 wt% or more and 3 wt% or less, vanadium 0.1 wt% or more and 5 wt% or less, tungsten 1 wt% or more and 7 wt% or less. The steel material of which the additive which satisfy | fills at least one of the following was added is used.

After primary processing is performed on such a substrate (ST1), quenching and high temperature tempering are performed (ST2). Subsequently, after performing a pre-plating process (ST3), the surface coating layer (plating layer) which consists of Ni-P alloy is formed by electroless plating (ST4). Subsequently, the substrate and the surface coating layer are subjected to heat treatment (ST5) to crystallize the surface coating layer and change the substrate into a tempering structure. Subsequently, after finishing processing (ST6) and finishing of surface coating layer (ST7) to a base material, a release film is coated on a surface coating layer (ST8).

In the manufacturing method in this embodiment, by using Mo, V, and W as a base material which improved the high temperature hardness, even if high temperature tempering is performed, the surface coating layer is not cracked. This is because a large amount of retained austenite is present immediately after quenching, but changes to the structure of low carbon martensite and martensite when high temperature tempering is performed.

In addition, the temperature in high temperature tempering needs to be 400-650 degreeC or less. This is because at temperatures lower than 400 ° C., there is little effect on the reduction of residual austenite, and when it exceeds 650 ° C., the softening of the substrate is remarkable. In addition, you may perform sub zero process instead of high temperature tempering. This is because the subzero treatment also has an effect of transforming retained austenite into martensite.

Formation of a surface coating layer uses Ni-P alloy, for example, Ni-P, Ni-PB, or Ni-PW. These structures are amorphous or partially amorphous in the plating state, and transform into a mixed structure of Ni and Ni ₃ P that are completely crystallized when heated at about 270 ° C. or higher.

It is necessary to make the temperature of heat processing more than the use temperature (namely, shaping | molding temperature of glass) of a metal mold | die. If the temperature is lower than the use temperature of the mold, dimensional change occurs during use, and the dimensional accuracy of the molded article is lowered. Too high a heat treatment temperature affects the plated surface, so the upper limit of the heat treatment temperature is about 700 ° C.

Next, the reason for using the forcing material of the component mentioned above as a base material is demonstrated. That is, C content was made into 0.3 wt% or more and 2.7 wt% or less. When C content is lower than 0.3 wt%, the volume shrinkage of the base material in tempering will become too small. On the other hand, if the C content exceeds 2.7 wt%, the volume shrinkage of the substrate is sufficient, but adverse effects such as lowering of toughness occur.

In addition, Cr content was made into 13 wt% or less. This is because if the Cr content exceeds 13 wt%, the retained austenite becomes difficult to decompose. In addition, there is no restriction | limiting in particular about the lower limit of Cr content.

About Mo, V, and W which are additives, Mo was 0.5 to 3 wt%, V was 0.1 to 5 wt%, W was 1 to 7 wt%. This is because when the amount of these additives is too small, the high temperature hardness of the substrate is not sufficient, and there is a risk of plastic deformation due to press pressure. In addition, since the cost becomes high when it makes more than necessary, an upper limit is set.

A mold having 100 µm of electroless Ni-P plating coated on a substrate of various components was fabricated, and the number of cracks generated during heat treatment and molding and the presence or absence of plastic deformation of the substrate when the glass was molded were examined. In Table 1, the relationship with the component of a base material, tempering temperature, a crack incidence rate, and the presence or absence of plastic deformation is shown. As the comparative example 7, the metal mold | die for plastic molding which performed the conventional heat processing as a comparative example is used. In addition, all the molding temperatures were 550 degreeC.

As can be seen from Table 1, in the molds (sample 5, specimen 6) produced based on the production method of the present invention, the occurrence of cracks and plastic deformation were not confirmed.

As mentioned above, in the manufacturing method of the metal mold | die for glass molding which concerns on this embodiment, and the metal mold | die for glass molding, while preventing a crack generate | occur | produce in a surface coating layer at molding temperature, the plastic deformation of a metal mold is prevented and the shape of a metal mold | die is prevented. It is possible to maintain a high accuracy and to increase its lifespan.

The present invention is not limited to the above-described embodiments. For example, the heat treatment of the substrate and the surface coating layer may be performed after the finishing treatment of the substrate and the finishing treatment of the surface coating layer. In addition, of course, various deformation | transformation is possible in the range which does not deviate from the summary of this invention.

According to the present invention, it is possible to prevent the occurrence of cracks in the surface coating layer at the molding temperature and to prevent plastic deformation of the mold, thereby maintaining the shape of the mold with high accuracy and increasing its life.

Claims (4)

At least one of 0.3 wt% or more and 2.7 wt% or less, chromium 13 wt% or less, molybdenum 0.5 wt% or more and 3 wt% or less, vanadium 0.1 wt% or more and 5 wt% or less, tungsten 1 wt% or more and 7 wt% or less. The base material is formed by quenching the steel material to which a satisfactory additive is added and tempering at 400 ° C or more and 650 ° C or less, On the surface of the said base material, the surface coating layer which consists of an amorphous Ni-P alloy is formed, By performing a heat treatment on this, the method for manufacturing a metal mold for glass molding, characterized in that to change the surface covering layer to the step structure of Ni ₃ P and Ni. The method of claim 1, wherein the surface coating layer is formed by electroless plating comprising Ni and P, Ni and P and B or Ni and P and W, The said heat processing is more than the shaping | molding temperature of glass, The manufacturing method of the metal mold for glass forming. At least one of 0.3 wt% or more and 2.7 wt% or less, chromium 13 wt% or less, molybdenum 0.5 wt% or more and 3 wt% or less, vanadium 0.1 wt% or more and 5 wt% or less, tungsten 1 wt% or more and 7 wt% or less. At the same time as quenching the steel material to which a satisfactory additive has been added, the substrate is formed by sub-zero treatment, On the surface of the said base material, the surface coating layer which consists of an amorphous Ni-P alloy is formed, By performing a heat treatment on this, the method for manufacturing a metal mold for glass molding, characterized in that to change the surface covering layer to the step structure of Ni ₃ P and Ni. The method of claim 3, wherein the surface coating layer is formed by electroless plating comprising Ni and P, Ni and P and B or Ni and P and W, The said heat processing is more than the shaping | molding temperature of glass, The manufacturing method of the metal mold | die for glass forming.

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