JP7043036B2 - Manufacturing method of nesting for new transfer molds - Google Patents

Description

INDUSTRIAL APPLICABILITY According to the present invention, a transfer mold nest used for manufacturing a product having a fine shape and structure can be manufactured easily and at low cost, and a transfer mold nest having excellent fine structure transfer accuracy can be manufactured. Regarding the method.

Currently, in many electronic devices and digital home appliances such as mobile phones, the direction of development is toward higher functionality, higher precision, and smaller size. If these products are made more accurate and smaller, the components constituting them also need to be made more accurate, smaller, and miniaturized. On the other hand, molds are generally used in the manufacture of mass-produced parts, and if parts are made highly accurate, miniaturized, and miniaturized, the molds are also required to be highly accurate, miniaturized, and miniaturized. In the manufacture of molds, it is required to respond to high precision, miniaturization, and miniaturization while satisfying the stability of quality, price reduction, and shortening of delivery time.

Here, when mass-producing miniaturized and miniaturized parts, a plurality of cutting dies capable of manufacturing tens to hundreds of parts at the same time are used. For this reason, when manufacturing a plurality of molds, a skilled worker manually forms a plurality of inverted shapes of parts in one block made of a mold material by using a machine tool (for example, a machining center). Finishing is done by polishing. Therefore, if the inverted shape of the component is miniaturized and miniaturized, the shape accuracy of the inverted shape is lowered due to the restriction of the tool shape, and there are problems of shape error and shape variation in the finishing process. When shape error and shape variation occur, there arises a problem that the mold quality cannot be stabilized and the delivery time cannot be shortened. Therefore, by accurately producing one prototype with the shape of the part to be manufactured, sandwiching this prototype with a block made of superplastic metal from above and below, and pressing it to transfer the shape of the prototype to the block, the mold quality. Disclosed is a method for manufacturing a stable mold (without shape error and shape variation) in a short delivery time (see, for example, Patent Document 1).

However, in the invention described in Patent Document 1, since the prototype is sandwiched between blocks made of a superplastic metal material from both sides to produce a split mold in which the inverted shape is transferred, the positioning of the split position on the product is very difficult. It is difficult to manufacture a plurality of die with stable quality by preventing shape error and shape variation.

Patent Document 2 describes a first step of transferring a parting surface shape based on a molded product mold to a first transfer mold, and a second transfer of a parting surface shape based on the first transfer mold. The second step of transferring to the mold and the plastic deformation by pressurizing the superplastic alloy plate arranged along the parting surface shape of the second transfer mold toward the second transfer mold under heating. Disclosed is a method for manufacturing a molding die, which comprises a third step of forming a parting face material and a fourth step of integrally molding a support mold on the back surface of the parting face material. Has been done.

However, the invention described in Patent Document 2 is a technique for manufacturing a large-sized mold in addition to the complicated process, and is not suitable for manufacturing a mold for manufacturing an article having a fine structure.

Patent Document 3 describes as a method for manufacturing a nest for a transfer die, which can manufacture a plurality of transfer dies that prevent shape errors and variations even if the product is highly accurate, miniaturized, and miniaturized, at a low cost and in a short delivery time. The first step of producing a master mold in which a prototype having the same shape as the product is formed using a material such as ceramics having high strength, hardness and deformation resistance at a high temperature of over 1200 ° C, and a temperature of 1200 ° C or less. The mold is made of a mold material exhibiting softness, and is excluded when the inverted shape of the master mold is transferred to the inside at a predetermined distance from the transfer surface on which the shape of the master mold is transferred. A columnar nesting member having a space for accommodating the material is placed in the heating furnace facing the master mold on the transfer surface side, and the nesting is performed up to a temperature range in which the mold material exhibits softness. The second step of heating the member to press the master mold and the nested member against each other to transfer the inverted shape of the master mold to the transfer surface side of the nested member, and the nest to which the inverted shape of the master mold is transferred. Disclosed is a method for manufacturing a nest for a transfer die, which comprises a third step of cooling a member and removing the die from the master die.

Japanese Unexamined Patent Publication No. 52-7326 Japanese Unexamined Patent Publication No. 2-169207 Japanese Unexamined Patent Publication No. 2010-214624

However, the invention described in Patent Document 3 has a problem that breakage or the like may occur when a master mold having a fine structure is manufactured by using a high-strength but brittle material such as ceramics. Further, when the inverted shape of the master mold is transferred to the mold material, it is necessary to heat it to a high temperature of about 1200 ° C., so that there is a problem that the energy cost at the time of manufacturing the nest for the transfer mold is high.

The present invention has been made in view of such circumstances, and it is possible to easily and inexpensively manufacture a nest for a transfer mold used for manufacturing a product having a fine shape and structure, and to improve the transfer accuracy of the fine structure. It is an object of the present invention to provide an excellent method for manufacturing a nesting for a transfer mold.

The present invention according to the above object is a method for producing a pair of nests for a transfer mold, which can be opened and closed at a split surface and has a cavity in which an inverted shape of the surface shape of a product is transferred in a closed state. The first step of forming a master mold made of one metal material and having a prototype having the same surface shape as at least a part of the surface shape of the product, and softening at a lower temperature than the first metal material. At least a part of the nested member made of the aluminum alloy is pressed against the master die while being heated to a temperature of 240 ° C. or higher and 400 ° C. or lower at which the first metal material does not soften and the aluminum alloy softens. After transferring the inverted shape of the surface shape of the prototype to the nested member, the arithmetic average surface roughness of the divided surface of the nested member to which the inverted shape of the surface shape of the prototype is transferred becomes 0.1 μm or more and 1 μm or less. As described above, the above problem is solved by providing a method for manufacturing a nest for a transfer die, which comprises a second step of cutting or grinding the surface on the side where the master die is pressed. ..

In the method for manufacturing a nest for a transfer die according to the present invention, it is preferable to heat the surface of the nesting member pressed by the master mold and its vicinity in the second step.

In the method for manufacturing a nest for a transfer mold according to the present invention, the first metal material may be a steel material for a mold.

In the method for producing a nest for a transfer mold according to the present invention, it is preferable that the aluminum alloy is the aluminum alloy A7075.

The method for manufacturing a nest for a transfer die according to the present invention may be a method for manufacturing a nest for an injection molding die of a resin material.

In the method for manufacturing a nest for a transfer mold according to the present invention, by using a metal material (first metal material) such as a steel material for a mold for forming a master mold, a master is compared with a case where a material such as ceramics is used. The risk of damage to the master mold during mold formation can be reduced. In particular, when a master mold having a fine shape and structure is required, the master mold can be formed with high dimensional accuracy while reducing the risk of breakage. Further, as the material of the nesting member, a second metal material that softens at a lower temperature than the first metal material used for manufacturing the master mold is used, and the transfer of the inverted shape of the master mold to the nesting member is performed by the first metal. Since the material is not softened and at least a part of the nested member is heated to a temperature at which the second metal material is softened, the nested member can be made with high transfer accuracy while reducing the energy cost as compared with the conventional method. Can be manufactured.

When an aluminum alloy such as aluminum alloy A7075 is used as the second metal material, the heating temperature of at least a part of the nested member at the time of transfer to the master type nested member is set to a low temperature of 240 ° C. or higher and 400 ° C. or lower. Therefore, the manufacturing cost of the nesting for the transfer mold can be significantly reduced. Further, since the mold releasability for a material such as a resin can be improved as compared with the case where a steel material for a mold is used as a nesting member, for example, a resin product having a fine structure including a fine shape having a diameter or width of 10 μm or more and 100 μm or less. It can be particularly preferably used as a nesting member for an injection molding die.

Further, by processing the split surface of the nested member to which the inverted shape of the prototype surface shape is transferred so that the arithmetic average surface roughness is 0.1 μm or more and 1 μm or less, it is generated from the air inside the cavity or the molten resin. There is no need to install a gas vent to discharge the gas.

It is schematic cross-sectional view which shows the schematic structure of the pair of transfer mold nests manufactured by the manufacturing method of the transfer mold nest which concerns on one Embodiment of this invention. It is a schematic cross-sectional view which shows the schematic structure of the master mold manufactured in the 1st step of the manufacturing method of the nest for the transfer mold. It is a schematic diagram which shows the 2nd process of the manufacturing method of the nest for the transfer die. It is a schematic diagram which shows the 2nd process of the manufacturing method of the nest for the transfer die. It is a schematic diagram which shows the process of manufacturing the nesting for a transfer die by cutting the nesting member which transferred the inverted shape of a master die in the manufacturing method of the nesting for a transfer die. It is a figure which shows an example of the shape of the master mold used for manufacturing the mold for injection molding of a microneedle.

As shown in FIGS. 1 to 4, the method for manufacturing a transfer mold nest according to an embodiment of the present invention (hereinafter, may be abbreviated as “method for manufacturing a transfer mold nest”) is as shown in FIGS. Manufactures a pair of transfer mold nests (fixed side nest 12 and movable side nest 13) that can be opened and closed on the divided surfaces 11 and 11a and have a cavity 14 in which the inverted shape of the surface shape of the product is transferred in the closed state. The first step of forming the master molds 21 and 21a, which are made of the first metal material and have the same surface shape as at least a part of the surface shape 22 of the product. And, at least a part of the nesting member 31 made of the second metal material that softens at a lower temperature than the first metal material is heated to a temperature at which the first metal material does not soften and the second metal material softens. The second step is to press the master dies 21 and 21a while transferring the inverted shapes 32 and 32a of the prototypes 23 and 23a to the nesting member 31.

Hereinafter, each step will be described in more detail.

<First step>
In the first step, the master molds 21 and 21a, which are made of the first metal material and have the same surface shape as at least a part of the surface shape 22 of the product, are formed. As the first metal material constituting the master molds 21 and 21a, any metal material capable of forming a master mold having an arbitrary size and shape by cutting or the like can be used, but the softening temperature is high (for example). , 400 ° C. or higher), preferably a metal material having a high hardness, which can be applied to the processing of fine shapes of 1 mm or less, preferably several tens of μm. Specific examples of the preferred first metal material include a steel material for a mold.

At least a part of the surface shape 22 of the product formed on the master molds 21 and 21a may be one of the surface shapes 22 of the product divided into two by the dividing surface D as shown in FIG. In the second step described later, when the nesting member 31 softened by heating is pressed against the master molds 21 and 21a, R is generated at the edge portion to prevent the transfer accuracy of the prototypes 23 and 23a from being lowered. As shown in FIG. 2, the surface shape 22 of the product may be divided into two by the dividing surface D, and a cutting margin having a predetermined thickness may be added to the shape. The master molds 21 and 21a can be formed by any method and device such as cutting using an arbitrary processing machine of a milling machine, but can be applied to processing a fine shape of 1 mm or less, preferably several tens of μm. Method is preferable.

<Second step>
As shown in FIGS. 3 and 4, in the second step, at least a part (shaded portion in FIG. 3) of the nested member 31 made of the second metal material that softens at a lower temperature than the first metal material. Preferably, the surface pressed by the master molds 21 and 21a and its vicinity are pressed against the master molds 21 and 21a while being heated to a temperature at which the first metal material does not soften and the second metal material softens. The inverted shapes 32, 32a of the prototypes 23, 23a are transferred to the nested member 31.

As the second metal material constituting the nesting member 31, any metal having a hardness that can be used as a nesting member of the mold by softening at a lower temperature than the first metal material constituting the master molds 21 and 21a. Can be used. Preferred examples of the second metal material include an aluminum alloy such as the aluminum alloy A7075. Due to the surface energy of the aluminum alloy A7075 (the water drop contact angle of the steel material for the mold is about 76 °, the water drop contact angle of the aluminum alloy A7075 is about 98 °), the mold releasability with respect to the resin. This is particularly preferable as a mold for injection molding of a resin material, particularly a mold for a resin product having a fine shape.

In the transfer of the inverted shape, the surface that presses the nested member 31 against the master molds 21 and 21a and its vicinity (the shaded portion in FIGS. 3 and 4) are not softened by the first metal material, and the second metal material is used. This is done by pressing the master molds 21 and 21a while heating to a softening temperature. At this time, at least a part of the master molds 21 and 21a may be heated at the same time. When the second metal material is aluminum alloy A7075, the heating temperature of the nesting member 31 is preferably 240 ° C. or higher and 400 ° C. or lower, and particularly preferably around 300 ° C. The heating can be performed by any means, but it is preferably performed by high frequency heating which can be locally heated and the heating temperature can be easily adjusted. The time required for transfer is about 1 to 3 minutes when the heating temperature is 300 ° C. and the second metal material is the aluminum alloy A7075.

In the second step, when the nested member 31 softened by heating is pressed against the master dies 21 and 21a, R is generated at the edge portion and the transfer accuracy of the prototypes 23 and 23a is prevented from being lowered. As shown in the above, when the surface shape 22 of the product is divided into two by the split surface D and a cutting margin of a predetermined thickness is added to the shape, the nest for the transfer die (fixed side nest 12 or movable). In order to manufacture the side nesting 13), as shown in FIG. 5, the surface of the nesting member 31, 31a after the inverted shape 32, 32a of the prototype is transferred is divided into the surfaces pressed by the master molds 21, 21a. It is necessary to cut or grind to the surface D (11, 11a). Cutting or grinding can be performed by any means.

The fixed side nest 12 and the movable side nest 13, which are a pair of nests for transfer dies thus obtained, can be used, for example, as nests for injection molding dies of resin products. Since it is possible to transfer a shape having a fine structure of 1 mm or less, the fixed side nest 12 and the movable side nest 13 are resin products having a fine structure such as microneedles having a diameter of about 100 μm, LED packages, and smartphone lenses. Can be suitably used as a mold for injection molding. In this case, the surface of the split surface 11 or 11a is not mirror-finished, and the joint surfaces 11 and 11a are formed from the cavity 14 formed between the fixed side nest 12 and the movable side nest 13 joined by the split surfaces 11 and 11a. Grinding or grinding so that the arithmetic average surface roughness (Ra) of the joint surfaces 11 and 11a is 0.1 μm or more and 1 μm or less so that a gas flow path through which the resin does not flow but can permeate is formed up to the outer periphery. By cutting or forming a groove (not shown) from the cavity 14 to the outer periphery of the joint surfaces 11 and 11a, the air existing inside the cavity 14 and the gas generated from the molten resin are discharged. It is no longer necessary to form a gas vent as in the case of conventional injection molding dies for resin products, and the processing process can be simplified. The arithmetic mean surface roughness (Ra) can be measured by any known method and apparatus.

In the present embodiment, the case where both the fixed side nest and the movable side nest are manufactured by using the method for manufacturing the transfer mold nest according to the present embodiment has been described, but only one of them is described in the present embodiment. It may be manufactured by the manufacturing method according to the form. Further, when the product shape is symmetrical with respect to the dividing surface, both fixed side nesting and movable side nesting may be manufactured using a single master mold.

Next, an example carried out for confirming the action and effect of the present invention will be described.
Example 1: Manufacture of nesting for transfer dies By cutting with a cBN radius end mill, a master die for microneedles having a shape as shown in FIG. 6 and having a diameter of 100 μm and a length of 1.2 mm is used for the die. It was formed on a block made of a steel material (ELMAX (registered trademark)). Next, the pressed surface of the nested member made of aluminum alloy A7075 and its vicinity were pressed against the master mold for a predetermined time while being heated to 300 ° C. by high frequency heating, and the inverted shape of the master mold was transferred. Then, the pressing surface side was cut until the divided surface was exposed to manufacture a pair of nests for transfer dies to which the inverted shape of the master die was transferred.

Example 2: Formation of Microneedle A cylinder having a diameter corresponding to the inner diameter of the microneedle is set at a position corresponding to the hollow portion of the microneedle by setting the transfer mold nest manufactured in Example 1 in the injection molding die block. Insert a shaped core (as a core, a concave convex shape may be formed at the position corresponding to the hollow part of the movable side nest), and injection molding is performed using polylactic acid, which is a biodegradable resin. went. It was confirmed that the microneedles to which the fine shape was transferred with high accuracy can be manufactured with almost no burrs or breakage at the time of mold release. It was confirmed that the manufacturing cost can be significantly reduced as compared with the case where the microneedles are manufactured using the conventional microfabrication.

10 Nesting for transfer mold 11, 11a Nesting surface 12 Fixed side nesting 13 Movable side nesting 14 Cavity 21, 21a Master mold 22 Product surface shape 23, 23a Prototype 31 Nesting member 32, 32a Prototype inverted shape D Dividing surface

Claims (5)

It is a method of manufacturing a pair of nests for transfer dies, which can be opened and closed at the divided surface and have a cavity to which the inverted shape of the surface shape of the product is transferred in the closed state.
A first step of forming a master mold, which is made of a first metal material and has a prototype having the same surface shape as at least a part of the surface shape of the product.
At least a part of the nested member made of an aluminum alloy that softens at a lower temperature than the first metal material is brought to a temperature of 240 ° C. or higher and 400 ° C. or lower at which the first metal material does not soften and the aluminum alloy softens. After pressing against the master mold while heating and transferring the inverted shape of the surface shape of the prototype to the nested member, the arithmetic average surface roughness of the divided surface of the nested member to which the inverted shape of the surface shape of the prototype is transferred is transferred. A method for manufacturing a nest for a transfer mold, which comprises a second step of cutting or grinding the surface on the side where the master mold is pressed so that the roughness is 0.1 μm or more and 1 μm or less. The method for manufacturing a nest for a transfer die according to claim 1, wherein in the second step, the surface of the nesting member pressed by the master mold and its vicinity are heated. The method for manufacturing a nest for a transfer mold according to claim 1 or 2, wherein the first metal material is a steel material for a mold. The method for manufacturing a nest for a transfer mold according to any one of claims 1 to 3, wherein the aluminum alloy is an aluminum alloy A7075. The method for manufacturing a nest for a transfer mold according to any one of claims 1 to 4, wherein the method is for manufacturing a nest for an injection mold of a resin material.

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