JP2000280258A - Production of mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a mold excellent in dimensional accuracy, lightweight properties and radiation properties economically for a short period. SOLUTION: A curable resin material containing a metal powder is pressed between a model mold made of graphite and a first mold matrix part made of graphite and a resin material layer is laminated on the first mold matrix part 13 to form a first mold semi-finished article and a cavity forming sheet is laminated on the surface of the resin material layer of the first mold semi- finished article and a curable resin material containing a metal powder is pressed between the cavity forming sheet and a second mold matrix part 23 made of graphite formed from the model mold to laminate the resin material layer on the second mold matrix part 23 to form a second mold semi-finished article and the resin material layers of the first and second mold semi-finished articles are cured to produce a mold wherein resin layers 16, 26 are laminated to th mold surfaces of the first mold matrix parts 13, 23 made of graphite.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a mold, and more particularly to a method of manufacturing a mold in which a mold surface resin layer is laminated on a surface of a graphite base material.

[0002]

2. Description of the Related Art In general, the manufacture of plastic molded products is as follows.
It is often performed by injection molding using a molding die or the like. The mold includes a first mold capable of being separated and combined with a second mold.
A mold is used in which a cavity composed of the mold surfaces of the first mold and the second mold is formed inside by the union. In the cavity of the molding die, at the time of manufacturing a plastic molded product, a high-temperature molten resin, a reaction resin raw material, or the like is injected or injected, cooled and solidified in the mold to a predetermined temperature, and then the molding die is opened. The desired plastic molding is removed.

Usually, in an injection mold, one of the first mold and the second mold has a convex shape with a protruding mold surface and is called a core mold or a male mold, and the other has a concave shape with a concave mold surface. It is often called a cavity type or a female type.
When one of the first mold and the second mold is fixed and the other is moved to open and close, one may be called a fixed mold and the other may be called a movable mold. Further, in a foaming mold or the like, when the first mold and the second mold are arranged to open and close in a vertical direction, one may be called an upper mold and the other may be called a lower mold.

[0004] There are resin molds, steel molds, molds, and electroforms in the mold for plastic molded products, but high dimensional accuracy is required and moreover, the molded product surface is free from pinholes and other defects. For molded products requiring appearance,
It is said that a steel material is preferable.

[0005]

However, in the conventional production of a steel material forming die, a steel material block is generally formed directly by a cutting process using an NC machine tool. Is heavy and difficult to handle,
Moreover, there is a problem that the cost increases. Furthermore, the NC cutting process for forming the mold surface includes a rough machining process, a rough machining process,
It is necessary to perform a plurality of steps including a medium processing step, a finishing processing step, and the like, and to exchange tools for each of the processing steps. There is a problem that it takes a long time and the cost increases. In particular, the concave mold surface is often used as a mold surface for forming the design-side surface of the molded product, and it is difficult to perform the NC cutting process including the plurality of steps on the concave mold surface. However, there is also a problem that the tool easily interferes with the peripheral edge of the concave mold surface, and special measures are required. Further, there is also a problem that a steel mold is heavy and difficult to handle as compared with a resin mold.

[0006] Further, regardless of the mold made of steel or resin, the heat dissipation of the mold itself is not sufficient.
It takes a long time to cool and solidify the resin filled in the cavity. Therefore, in order to shorten the molding time, a refrigerant circulation pipe is buried near the mold surface of the molding die, and the refrigerant is flowed through the refrigerant circulation pipe. However, there is a drawback that extra work for embedding the refrigerant circulation pipe in the mold is required during the production of the mold, and the production period of the mold is prolonged.

The present invention has been made to solve the above-mentioned problems of the prior art, and provides a method of manufacturing a molding die which can be economically manufactured in a short period of time, and is excellent in dimensional accuracy, light weight and heat radiation. To provide.

[0008]

In order to achieve the above object, the present invention provides a first mold and a second mold having a mold surface made of a resin layer on the surface of a graphite base material. A method of manufacturing a molding die in which a cavity is formed by combining a die and a second die, wherein a model die made of graphite having a die surface molding surface for the first die is formed by processing a graphite block. A first mold base material processing step of obtaining a graphite first mold base material having a mold surface for laminating a resin layer of the first mold surface by processing a graphite block; A release treatment is performed on the mold surface of the model mold, and a curable resin material containing a metal powder is placed between the mold surface of the model mold and the mold surface of the first mold base. Filled model mold surface A first mold resin layer laminating step of laminating the resin material layer having the transferred shape on the mold surface of the first mold base to form a first mold semi-finished product; A second mold base member made of graphite having a mold surface for laminating a resin layer by machining the model mold.
A mold base material processing step, a cavity forming sheet laminated on a surface to be a mold surface in the resin material layer of the first mold semi-finished product, and a surface having releasability in the cavity forming sheet opposed thereto; A resin material layer formed by filling and shaping a curable resin material containing metal powder between the mold surface of the second mold base and the mold surface is laminated on the mold surface of the second mold base. The method includes a second mold resin layer laminating step of forming a mold half-finished product, and a curing step of promoting the curing of the resin material layers of the first mold semifinished product and the second mold semifinished product.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the accompanying drawings. FIG. 1 is a cross-sectional view schematically showing an example of a mold obtained by the manufacturing method of the present invention, and FIGS.
FIG. 2 is a schematic process drawing in manufacturing the mold of the present invention. The present invention is not limited to an injection mold, but is applied to a mold used for molding a plastic molded product into a mold surface shape, such as a foam mold and a blow mold. Is done.

A molding die 10 shown in FIG. 1 is an injection molding die obtained by the manufacturing method of the present invention.
A cavity 21 having a product shape when the mold is closed.
Mold surface 12 having a substantially concave shape and mold surface 2 having a substantially convex shape
2 is provided on the mold-matching side, and is mounted on an injection molding apparatus (not shown) via mounting plates 41 and 42 provided on opposite back sides. The first mold 11 in this example is also referred to as a cavity mold or a fixed mold, in which a sprue 32 communicating with the cavity 31 is formed, and the molten resin is injected into the cavity 31 from the screw of the injection device via the sprue 32. It has become. In contrast, the second
The mold 21 is also called a core mold or a movable mold, and can be slid in the direction of the first mold 11 by a plunger of an injection molding apparatus.

The first mold 11 and the second mold 21 are composed of base materials 13 and 23 and resin layers 16 and 26 on the surface. The base materials 13 and 23 are made of a first mold 11 and a second mold 21.
And imparts required strength, rigidity and the like to the mold 10. The base members 13 and 23 are formed by processing a graphite block into a required shape.
Graphite is also referred to as graphite and has excellent lightness and thermal conductivity. Therefore, the molding die 10 in which the base materials 13 and 23 are made of graphite is lighter than the conventional steel-made molding die, and is excellent in natural cooling.
The molten resin injected into the cavity 31 can be quickly cooled and solidified, and the refrigerant circulation pipe required in the conventional molding die can be eliminated. Base material part 1
Known graphites used for forging dies, die-casting dies, electrode materials and the like can be used as the graphite constituting 3, 23. As an example, graphite EX series (trade name: EX-50, EX-
70, etc.) and the ED series (trade names: ED-2, ED-
3, ED-4, etc.).

The resin layers 16 and 26 on the surface correspond to the base material 1.
The precision mold surfaces 12 and 22 are formed at least at the mold surface positions on the surfaces of the base materials 3 and 23 and the base material portions 13 and 2 are formed.
3 is provided at a required portion of the surface, and has an effect of protecting the base material portions 13 and 23 and the like. Since the surface resin layers 16 and 26 are directly cured on the surfaces of the base members 13 and 23, the bonding with the graphite base members 13 and 23 is strong.
Reference numeral 16a denotes a resin layer of the mold surface 12 forming the design side surface of the plastic molded product, and 26a denotes a resin layer of 22 forming the back surface of the plastic molded product.

The resin layers 16 and 26 are preferably made of a resin material for a resin mold in which a metal powder and an epoxy resin are mixed, since they are excellent in moldability and have good thermal conductivity. In particular, a mixture of alumina or aluminum powder and an epoxy-based resin is preferable because of its excellent lightness. The content of the metal powder is appropriately determined according to the type of the metal powder, but is generally 65% by weight to 85% by weight. As such a resin material, a known resin material can be used. As an example, Quinnate CT manufactured by Zeon Rise Co., Ltd. is used as a mixture of alumina powder and epoxy resin.
R series, Quinnate ME manufactured by Zeon Rise Co., Ltd. as a mixture of aluminum powder and epoxy resin
Z series (for example, Quinnate MEZ200 having an aluminum powder content of 75% by weight), and other examples include Vistax NX-1101 manufactured by Pernox Japan Limited. Further, it is preferable that the resin material contains a required amount of graphite powder, particularly 3 to 7% by weight of a resin which has passed through a 30 to 80 mesh sieve (filter), since a better mold surface can be obtained.

The resin layers 16 and 26 have an appropriate thickness depending on the shape of the mold surface, the size of the molding die, and the like, but generally have a thickness of about 3 to 5 mm. Further, the resin layers 16 and 26 may be provided so as to cover the entire surfaces of the base members 13 and 23, but in this example, the mold surfaces 12 and 2 are provided.
Base material 1 excluding the surface on the mounting side opposite to 2
3, 23 are provided on the surface. Further, when it is desired to form a textured pattern made of fine irregularities on the design side surface of the plastic molded product, the molded product is formed on the mold surface 12 of the first mold 11 which forms the design side surface of the plastic molded product. The grain pattern formed of the fine irregularities to which the grain pattern is transferred is formed.

Next, a first embodiment of the molding die 10 will be described in detail with reference to FIGS. The production of the molding die 10 includes a model mold processing step, a first mold base material processing step, a first mold resin layer laminating step, a second mold base material processing step, a second mold resin layer laminating step, and a curing step. Including.

In the model die machining step, as shown in FIG. 2, a model die 51 is formed from a graphite block 50 having required dimensions by precision machining such as cutting using an NC machine tool. This model mold 51 is the first mold 11
Which has a convex mold surface molding surface 52 in which the mold surface 12 is inverted, and is formed to be larger than the base material portion 23 of the second mold 21 by the thickness of the resin layer 26 and the cavity 31 on the surface. You. Further, since the model mold 51 is formed into the second mold 21 by subsequent processing, the model surface 51 of the second mold 21 is formed to have a convex shape as in this example. Becomes Therefore, even when complicated precision machining is performed, unlike the machining of the concave surface, the tool does not easily hit the surface of the model die 51, and the work is facilitated. In addition, this model type machining process and the first
The order of the mold base material processing step may be any order.

In the first die base material processing step, as shown in FIG. 3, the base material portion 13 of the first die 11 is processed from a graphite block 60 having a required size by an NC machine tool or the like. The base material portion 13 is formed smaller than the final shape of the first mold 11 by the thickness of the resin layer 16 on the surface, and the portion corresponding to the concave mold surface 12 is smaller than the concave shape of the mold surface 12. The surface 14 for the mold surface has a large concave shape. Note that the processing of the first mold base material portion 13 does not form a final mold surface, and therefore does not require precision machining, and can be rough machining. Therefore, the work is simplified and can be completed in a short time.

Next, a first type resin layer laminating step is performed. In this step, first, as shown in FIG.
1, the mold surface forming surface 52 of the convex shape is turned upward, and the frame member 71 that is taller than the thickness of the model mold 51 surrounds the periphery of the side surface of the model mold 51, and the upper surface of the model mold 51 surrounded by the frame material 71 After applying the release agent to the inner surface of the frame member 71, the resin material P is disposed on the upper surface of the model die 51 in a required amount. Then, the base material portion 13 of the first mold is lowered from above the model mold 51 so that the concave mold surface 14 faces downward, and the curable resin material P is brought into contact with the model mold 51. Pressing is performed between the 1-type base material portions 13. At this time, the distance S1 between the side surface of the first mold base material portion 13 and the frame material 71,
The distance S2 between the mold base material 13 and the model mold 51 is the first
The thickness is made equal to the thickness of the resin layer 16 of the mold 11. The resin material P is pressed by the press and filled between the mold surface forming surface 52 of the model mold 51 and the mold surface 14 of the first mold base material portion 13 to be shaped. In this example, the first mold is used. Base material part 13
And between the frame members 71. And the resin material P
Becomes a resin material layer 16A covering the surface of the first mold base material portion 13 and adheres to the base material portion 13 to form the first mold semi-finished product 11A. At this time, when the resin component of the curable resin material P is a general epoxy resin, the resin material layer 16A is usually in the middle of curing.

As the curable resin material P, as described above, a metal powder, preferably an aluminum powder or a mixture of an alumina powder and an epoxy resin is used. Further, preferably, graphite powder is mixed as described above. In this case, bubbles which are easily entrained when the resin material P is pressed or the like are absorbed by the graphite, so that fine voids are less likely to be formed in the formed resin layer 16. As the graphite powder, a powder in the above-described range except for lumps by passing a graphite powder or a granular material generated when a graphite block is cut in the model die processing step or the first die base material part processing step through a sieve is used. Is economical.

Next, a second mold base material processing step is performed. In this step, the frame member 71 is removed, the model die 51 is taken out, and the model die 51 is removed by an NC machine tool or the like as shown in FIG.
The first surface is cut off by a required amount to form a second mold base member 23. The cut amount at this time is made equal to the thickness of the resin layer 26 of the second mold 21. Reference numeral 23a denotes a mold surface having a convex shape.

In the second mold resin layer laminating step, as shown in FIG. 6, the first mold semi-finished product 11A obtained in the first mold resin layer laminating step is formed by turning the concave mold surface 14 side upward. The spacer sheet 70 having a thickness equal to the thickness of the cavity 31 of the molding die 10 is laminated on the upper surface of the resin material layer 16A which is to be the mold surface, and is disposed around the side surface of the first mold semi-finished product 11A. The upper part of the first mold semi-finished product 11A is surrounded by the frame material 81 thus formed. The spacer sheet 70 is preferably made of a material to which the resin material P does not adhere (for example, fluororesin). The surface of the exposed resin material layer 16A of the first semifinished product 11A, the inner surface of the frame material 81, and if necessary. A release agent is applied to the surface of the spacer sheet 70. Then, a required amount of the same curable resin material P as described above is disposed on the upper surface of the first mold semi-finished product 11A, and the second mold base material 23 is set so that the convex mold surface 23a faces downward. The resin material P on the first mold semi-finished product 11A is pressed down from above the first mold semi-finished product 11A. At this time, the interval S3 between the second mold base member 23 and the frame member 81 and the interval S4 between the second mold base member 23 and the first mold semi-finished product 11A at the time of the lowest descend are the second mold resin layer. 26. By the pressing, the resin material P is pressed and filled between the spacer sheet 70 of the first mold semi-finished product 11A and the mold surface 23a of the second mold base material portion 23, and further spreads around the second mold base material 23 to form the second mold material. The space between the mold base member 23 and the frame member 81 is also filled and shaped into that state to form a resin material layer 26A, which together with the second mold base member 23 constitutes a second mold semi-finished product 21A.

In the curing step, the frame material 81 is removed from the first mold semi-finished product and the second mold semi-finished product, and the spacer sheet 7
7, the first mold semi-finished product 11A and the second mold semi-finished product 21A are housed in a heating furnace 75 or the like, as shown in FIG. Layer 16
A and 26A are heated and further cured to be completely cured. Thereby, the resin material layers 16A, 26A
Cures into resin layers 16 and 26, each of which has a base material 1
The first mold 11 and the second mold 21 are firmly bonded to the molds 3 and 23. Reference numeral 76 denotes a heating device such as an electric heater.

The curing step is performed in the first semifinished product 1
It may be performed separately for 1A and the second mold semi-finished product 21A. For example, with respect to the first mold semi-finished product 11A, after the first mold resin layer laminating step, a curing step of allowing the curing to proceed by leaving it as it is for a predetermined time or by heating or the like is performed. Regarding 21A, after the second-type resin layer laminating step is completed, a curing step is performed by leaving it as it is for a predetermined time or heating it. In addition, the first
A curing step may be included in the mold resin layer laminating step or the second mold resin layer laminating step. In other words, the curing step may be performed by leaving the press in the first type resin layer laminating step or the second resin layer laminating step and leaving it as it is for a predetermined time. Further, the progress of curing is not limited to leaving or heating alone, and appropriate means is adopted depending on the required mold manufacturing period and the used cured resin material.

After completion of the curing step, sprue formation, etc.
By finishing the necessary parts of the injection mold, the desired mold 10 as shown in FIG. 1 can be obtained.

When a more precise mold surface shape is required,
For example, when a concave portion for forming a rib, a convex portion for forming an ejector pin insertion hole, or the like is required on the mold surface, after the above-described curing step, electric discharge machining is performed on a desired mold surface portion before finishing. This electric discharge machining includes a resin layer surface shaving step and an electric discharge machining step. Hereinafter, a case in which electric discharge machining is performed on the second mold 21 will be described as an example.

In the resin layer surface shaving step, as shown in FIG.
2a is ground (polished) with a polishing tool K to increase the exposure of the metal powder buried in the resin and to increase the conductivity of the surface 22a to be subjected to electrical discharge machining. Papers (paper file, cloth file, etc.) can be used as the polishing tool K.

In the electric discharge machining step, as shown in FIG. 9, a second mold 21 for electric discharge machining is immersed in an insulating machining solution L, and the surface 22a to be subjected to electric discharge machining is subjected to electric discharge machining with an electrode 71 to obtain a desired shape. To The electric discharge machining at this time is performed according to a machining shape or the like according to a normal electric discharge machining.

As a second embodiment of the present invention, a description will be given of a method of manufacturing a molding die for forming a grain pattern having fine irregularities on the surface of a plastic molded product. In this case, the following first-type crimped resin layer forming step is performed instead of the first-type resin layer laminating step in the first embodiment.

In the step of forming the first type resin layer with a grain pattern,
As shown in FIG. 10, a grain pattern providing sheet 73 is disposed on a mold surface forming surface 52 of a model die 51 for molding a mold surface forming a surface of a plastic molded product, and the grain pattern providing sheet 73 and the first mold base are provided. The curable resin material P is pressed between the mold surface 14 of the material portion 13 to fill the space between the grain pattern imparting sheet 73 and the mold surface 14 of the first mold base material portion 13, and the crimp pattern imparting sheet 73 is filled. The resin material layer 16B to which the grain pattern has been transferred is shaped and laminated on the mold surface 14 of the first mold base material portion 13 to form the first mold semi-finished product 11A. The grain pattern imparting sheet 73 is made of a sheet of a resin or the like having a grain pattern formed on the surface by vacuum molding or the like, and the grain pattern side faces the outer surface, that is, the mold surface 14 of the first mold base 13. Then, it is temporarily fixed to the mold surface molding surface 52 with a double-sided tape or the like. In addition, this grain pattern imparting sheet 7
3 is made of a material having releasability, or is made to have releasability by applying a surface of a release agent. In addition,
The same steps as those of the above-described embodiment are performed, except that the step of forming the first-type crimped resin layer is performed instead of the step of laminating the first-type resin layer. The frame member 71 is then removed, and the first mold semi-finished product 11A and the model mold 51 are separated. At this time, the grain pattern imparting sheet 73 remains on the model die 51, and before the second die base material processing step, the model die 51 is processed.
Removed from

As a third embodiment of the present invention, instead of pressing the resin material in the first-type resin layer laminating step and the second-type resin layer laminating step of the first embodiment, the resin material is formed by press-fitting the curable resin material. To the mold surface 1 of the first mold base 13
A case will be described in which the space between the mold surface 4 and the mold surface forming surface 52 of the model mold 51 and the space between the cavity forming sheet 70 of the first mold semi-finished product 11A and the mold surface 23a of the second mold base material 23 are filled. Other steps are the same as in the first embodiment.

That is, in the first mold resin layer laminating step in the third embodiment, as shown in FIG. 11, the mold surface forming surface 52 of the model mold 51 and the mold surface of the first mold base material 13 are used. The first mold base material portion is set so that the space S2 between the first mold base material 14 and the space S1 between the side surface of the first mold base material portion 13 and the frame material 71 are equivalent to the thickness of the resin layer 16 on the first mold surface. 13 and the model mold 51 are arranged so as to face up and down. A mold release agent is applied to at least the mold surface forming surface 52 of the model mold 51, and the first mold base 13 is held above the model mold 51 by a support member (not shown). Then, the curable resin material P is connected to the model mold 51 by a well-known pressure pump (also referred to as a mono pump or a snake pump) 80 from a gap between the upper side surface of the first mold base 13 and the frame 71. Between first mold base material portions 13 and first mold base material portions 13
And between the frame material 71 and the resin material layer 16A
1A semi-finished product 11A laminated on the first mold base 13
To manufacture. At the time of press-fitting the resin material P, the frame 71 and the first mold base 13 excluding the nozzle position of the pressure feed pump 80 are used.
The upper end 75 of the gap between the side surfaces is preferably closed so that the resin material P does not leak. The frame 71 is then removed, and the first semifinished product 11A and the model mold 51 are separated.

In the second mold resin layer laminating step in the third embodiment, as shown in FIG. 12, a cavity forming sheet is formed on the mold surface of the resin material layer 16A of the first mold semi-finished product 11A. 70, and a gap S between the cavity forming sheet 70 and the mold surface 23a of the second mold base member 23.
4. The space S3 between the side surface of the second mold base material portion 13 and the frame material 81
The second mold base 13 and the semifinished mold 11A are arranged vertically facing each other so as to have an interval corresponding to the thickness of the resin layer 26 on the surface of the second mold. Surround with. In addition, the first around the cavity forming sheet 70
A release agent is applied to the surface of the mold semi-finished product 11A and, if necessary, to the surface of the cavity forming sheet 70.
The second mold base member 23 is held above the first mold semi-finished product 11A by a support member (not shown). Then, from the gap between the upper side surface of the second mold base member 23 and the frame member 81,
The curable resin material P is filled between the first mold semi-finished product 11A and the second mold base material portion 23 and between the second mold base material portion 23 and the frame material 81 by a known pressure pump 80, whereby the resin material is filled. A second mold semi-finished product 21A on which the layer 26A is laminated is manufactured.
At the time of press-fitting the resin material P, it is preferable to close the upper end 85 of the gap between the side surface of the frame member 81 and the side surface of the second mold base member 23 except for the nozzle position of the pressure feed pump 80 so that the resin material P does not leak.

As a fourth embodiment, a description will be given of a method of manufacturing a molding die for forming a mold surface for a plastic molded article having a grain pattern when the resin material is press-fitted to form a first mold resin layer. . In the fourth embodiment, the following first-type crimped resin layer laminating step is performed in place of the first-type resin layer laminating step in the third embodiment, and the other steps are the same as in the third embodiment. To do.

In the laminating step of the first type of resin layer with a grain pattern of the fourth embodiment, as shown in FIG. 13, first, the grain-patterned sheet 73 having a grain pattern formed on the surface thereof is placed on the grain-pattern side surface. Is temporarily fixed to the mold surface forming surface 52 of the model mold 51 with a double-sided adhesive tape or the like so that the textured sheet 73 and the first mold base 1
The first mold base member 13 is arranged facing the upper part of the model mold 51 so that the distance S2 between the mold surface 3 and the mold surface 3 is equal to the thickness of the mold surface resin layer 16a of the first mold 11. Hold with a support member that does not. At this time, the distance S1 between the side surface of the first mold base material portion 13 and the frame member 71 surrounding the side surface is:
The thickness of the resin layer 16 covering the side surface of the first mold 11 is made equal to the thickness of the resin layer 16.
A release agent is applied to the surface of the sheet 1 on which the grain pattern imparting sheet 73 is not placed, and further to the surface of the grain pattern imparting sheet 73 as needed.

Next, the curable resin material P is press-fitted from the upper gap between the side surface of the first mold base portion 13 and the frame member 71 by the pressure pump 80, and the surface of the grain pattern imparting sheet 73 and the first mold base are contacted. The resin material layer 16B with a grain pattern, which is filled between the mold surface 14 of the material part 13 and the grain pattern is transferred, is laminated on the surface of the first mold base material 13 to form the first mold semi-finished product 11A. I do. In this example, the resin material layer 16 </ b> B
Are formed in a series from the mold surface 14 to the side surface of the first mold base material, but only the surface of the portion laminated on the mold surface 14 has a grain pattern. When the resin material P is press-fitted, the upper end 75 of the gap between the frame member 71 and the side surface of the first mold base member 13 except for the nozzle position of the pressure feed pump 80 should be closed so that the resin material P does not leak. preferable. Further, the frame material 71 is removed thereafter, the first mold semi-finished product 11A and the model mold 51 are separated, and the grain pattern imparting sheet 73 remaining on the model mold 51 side is subjected to a second mold base material processing step. It is removed from the model mold 51 before.

[0036]

According to the method of manufacturing a molding die of the present invention,
Since the model die finally becomes the base material of the first mold, no extra material is required, which is economical. In addition, the operation of manufacturing the model die is also a part of the work of manufacturing the base material of the first die. Because
There is no waste in the work, and the mold can be manufactured efficiently.
In addition, the precision machining operation using an NC machine tool or the like requires only the model mold, and the mold surface can be formed by filling with the curable resin material. Therefore, the construction period required for the mold production can be shortened, and it is economical. Further, since it is possible to perform the electric discharge machining of the mold surface and the formation of the mold surface having a grain pattern, it is possible to meet various requirements for the mold surface shape.

Also, since the molding die obtained by the practice of the present invention is composed of a combination of a graphite base material and a resin layer on the die surface, it has excellent cooling properties and can eliminate the need for a refrigerant circulation pipe. This can also shorten the manufacturing period of the mold and reduce the cost of the mold. Furthermore, the obtained mold can be reduced in weight to about one third to one fifth compared with a conventional steel mold, and is easy to handle. In addition, since plastic shrinkage is smaller than that of a conventional resin mold, a plastic molded product can be molded with high precision. In addition, since there is no need to provide a coolant supply facility or the like at the installation location of the mold, the overall facility costs can be significantly reduced.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing an example of a mold obtained according to an embodiment of the present invention.

FIG. 2 is a schematic view showing a model die processing step when manufacturing a molding die of the present invention.

FIG. 3 is a schematic view showing a first mold base material processing step.

FIG. 4 is a schematic view showing a first type resin layer laminating step.

FIG. 5 is a schematic view showing a second mold base material processing step.

FIG. 6 is a schematic view showing a second type resin layer laminating step.

FIG. 7 is a schematic view showing a curing step.

FIG. 8 is a schematic view showing a resin layer surface shaving step.

FIG. 9 is a schematic view showing an electric discharge machining process.

FIG. 10 is a schematic view showing a step of laminating a resin layer with a first type grain pattern.

FIG. 11 is a schematic view showing another embodiment of the first type resin layer laminating step.

FIG. 12 is a schematic view showing another embodiment of the second type resin layer laminating step.

FIG. 13 is a schematic view showing another embodiment of the step of laminating the resin layer with the first type grain pattern.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Molding die manufactured by this invention 11 1st type | mold 11A 1st type | mold semi-finished product 12 1st type | mold type | mold surface 12a Surface to be electrical-discharge machined 13 1st type | mold base material part 14 Surface for 16 types 1st type resin Layer 16a Resin layer on mold surface 16A Resin material layer 16B Resin material layer with embossed pattern 21 Second mold 21A Second mold semi-finished product 22 Second mold surface 23 Second mold base material 26 Second mold resin layer 26a Resin layer on mold surface 31 Cavity 50, 60 Graphite block 51 Model mold 52 Mold surface molding surface 70 Cavity forming sheet 73 Grained sheet 80 Pressure pump P Curable resin material

Claims (7)

[Claims] 1. A first mold having a mold surface (12, 22) made of a resin layer on the surface of a graphite base material portion (13, 23).
The first mold (1) comprises a mold (11) and a second mold (21).
A method for producing a molding die (10) in which a cavity (31) is formed by combining 1) and a second die (21), wherein a molding surface forming surface (52) for the first die (11). Processing step of obtaining a graphite model die (51) having a shape by processing a graphite block (50), and a die surface for laminating a resin layer (16a) on the die surface of the first die (11). A first mold base material processing step of obtaining a graphite first mold base material part (13) having (14) by processing a graphite block (60); and a mold surface forming surface (52) of the model mold (51). The mold surface forming surface (52) of the model mold (51) and the mold surface (1) of the first mold base material (13) are subjected to a release treatment.
The resin material layer (16A) in which the shape of the mold surface molding surface (52) of the model mold (51) is transferred by filling a curable resin material (P) containing metal powder between the first mold and the first mold. Base material (1
A first mold resin layer laminating step of forming a first mold semi-finished product (11A) by laminating on the mold surface (14) of (3); and a resin layer (26a) of the mold surface of the second mold (21). A) a second mold base material processing step of obtaining a graphite second mold base material (23) having a mold surface (23a) for laminating the mold by processing the model mold (51); Resin material layer (16A) of mold semi-finished product (11A)
The cavity forming sheet (7
0) are laminated, and the releasable surface of the cavity forming sheet (70) and the second mold base member (23) are opposed to each other.
A resin material layer (26A) in which a curable resin material (P) containing metal powder is filled and shaped between the mold material surface (23a) and the mold surface (23a).
A second mold resin layer laminating step of forming a second mold semi-finished product (21A) by laminating the first mold semi-finished product on the mold surface (23a) of the second mold base material portion (23); (11A) and a curing step for promoting the curing of the resin material layers (16A, 26A) of the second mold semi-finished product (21A). 2. A mold forming surface (52) of a model mold (51) in place of the first mold resin layer laminating step, wherein a crimped pattern imparting sheet 73 having a grained pattern formed on its surface is formed so that the grained pattern becomes an outer surface. And the grain-patterned sheet 7 provided to face
A curable resin material (P) containing a metal powder is filled between the surface having releasability of No. 3 and the mold surface (14) of the first mold base material (13), and the grain-patterned sheet is filled. The first mold material semi-finished product (11A) is formed by laminating the resin material layer (16B) to which the grain pattern of 73 has been transferred onto the mold surface (14) of the first mold base material (13). 2. The method according to claim 1, wherein a step of forming a resin layer with a mold grain pattern is performed. 3. The mold surface of the first mold (11) has a concave shape, and the mold surface (22) of the second mold (21) has a convex shape. 5. The method for producing a molding die according to 4. 4. The method according to claim 1, wherein the curable resin material (P) contains graphite powder. 5. The production of a molding die according to claim 4, wherein the graphite powder has passed through a sieve of 30 to 80 mesh and is contained in the curable resin material (P) in an amount of 3 to 7% by weight. Method. 6. The graphite powder used in the model block processing step and / or the first mold base part processing step and / or the graphite powder generated during the graphite block processing step is used.
A method for producing the molding die according to the above. 7. After the curing step, a surface of the resin layer to be subjected to electrical discharge machining (12a) is shaved to perform a resin layer surface shaving step of increasing the conductivity of the predetermined surface (12a). 7. The method according to claim 1, wherein an electrical discharge machining step is performed on the mold.