JP6475446B2 - Mold manufacturing method - Google Patents

Description

The present invention relates to a method for manufacturing a mold for resin molding having a fluid passage for cooling or heating.

  For molds used for injection compression molding (heat & cool molding) with unsaturated polyester resins such as SMC, BMC, etc. for resin molded products, on the back side of the metal shell constituting the cavity, for cooling (or for heating) For example, a pipe made of metal such as copper for passing the fluid is attached by, for example, brazing (see, for example, Patent Document 1). Conventionally, there has also been provided a method for producing a resin molding die having excellent surface transferability by using an electroforming method (see, for example, Patent Document 2).

JP2011-98514A Japanese Patent Publication No. 4-27316

  In the case where a metal pipe is brazed to the outer surface of a metal shell as in Patent Document 1, since the distance between the pipe and the cavity surface is relatively large, the fluid passing through the pipe and the cavity surface of the mold The efficiency of heat exchange between the two is low, and it takes time to adjust the temperature, resulting in a long molding cycle. There was also a problem that the pipe would come off the mold. Therefore, Patent Document 2 discloses a technique in which a fluid passage is integrally formed in an electrodeposited metal layer by electroforming instead of providing a separate pipe in a mold.

  In this technology, a cavity is formed by electroforming, a communicating part forming body such as a low melting point solder is added to the fluid passage formation position on the back surface of the cavity, and electroforming is performed again to form an outer shell layer. After that, the fluid passage is formed by removing the communication portion forming body. However, as in Patent Document 2, a die manufactured by electroforming does not provide sufficient strength as a die, and is easily deformed or damaged particularly when used for compression molding (press molding). There is a problem that will cause. In this case, it is possible to obtain a mold having a large thickness by electroforming for a long time, but the manufacturing cost is significantly increased.

The present invention has been made in view of the above circumstances, and an object thereof is a resin molding die integrally having a fluid passage, and efficiency of heat exchange between a fluid passing through the fluid passage and a product surface. The object of the present invention is to provide a method for producing a mold having a high mechanical strength.

The method for producing a mold according to the present invention includes a surface electrodeposited metal layer whose surface constitutes a product surface, and a backside metal layer disposed on the backside and having a thickness larger than the surface electrodeposited metal layer, A method for producing a mold for resin molding having a fluid passage for cooling or heating, wherein the back side metal layer is formed by casting or shaping from a steel material, and the back side A groove forming step for forming a groove to be the fluid passage on the surface side of the metal layer, and after the groove forming step, the entire back surface side metal layer including the inner surface of the groove is made of ceramic. A heat insulating layer forming step of providing a heat insulating layer by thermal spraying; a vanishing material attaching step of disposing a dissipative material removable by chemical or physical means in the groove covered with the heat insulating layer; and the back surface Cover the surface of the side metal layer with the vanishing material Having characterized in that the containing the electrodeposition step is formed by electroplating the surface conductive Chakukinzoku layer, and a removal step you forming the fluid passage by removing the fugitive material (the invention of claim 1) .

  According to this invention, a metal mold | die becomes a two-layer structure of the surface electrodeposition metal layer located in the surface side, and the back surface side metal layer located in the back surface side and thicker than the surface electrodeposition metal layer. At this time, the back-side metal layer is formed by casting or shape processing (metal layer forming step) from steel, so that it can be obtained easily and inexpensively but can have a sufficiently large thickness. The strength of the whole can be increased. In this case, in the case of a mold having a relatively simple (simple) shape, shape processing (mechanical processing such as machining) from a steel material can be employed.

  The surface electrodeposition metal layer on the front side becomes a dense metal layer obtained by electroplating (electrodeposition process), and the surface roughness of the back side metal layer obtained by casting or shape processing from steel material is rough. However, a sufficiently smooth and dense surface of the mold can be obtained so as to cover the unevenness. The surface electrodeposited metal layer has a high bonding strength with respect to the back-side metal layer, and can be relatively thin. Therefore, the surface electrodeposited metal layer can be easily formed (including machining) and the manufacturing cost can be reduced.

  And the groove | channel is formed in the surface side of a back surface side metal layer (groove formation process), and the lossless material is embedded in the groove | channel (disappearance material attachment process), a back surface side metal layer and a loss property material A surface electrodeposition metal layer is formed so as to cover the surface (electrodeposition process). As a result, a cavity filled with the disappearing material is formed inside the mold, and the disappearing material is removed (removal step), so that the cavity becomes a fluid passage. As a result, the fluid passage having a small cross section can be formed to have an arbitrary shape. Moreover, since the fluid passage is formed just outside the thin surface electrodeposited metal layer, the heat exchange efficiency between the cooling or heating fluid and the surface electrodeposited metal layer is high, the temperature control performance is excellent, rapid heating and It can easily cope with rapid cooling. Further, the entire surface electrodeposited metal layer can be uniformly cooled and heated, and the temperature distribution can be improved.

In the present invention, the surface including the inner surface of the groove of the back side metal layer, Ru can be provided a heat insulating layer. In this case, after the groove forming step, a heat insulating layer forming step of providing a heat insulating layer including the inner surface of the groove on the surface of the back side metal layer is performed, and in the vanishing material attaching step, It covered the Ru can be made to place the fugitive material in the groove. Thus, by providing the heat insulating layer on the surface including the inner surface of the groove of the back side metal layer, the heat of the cooling or heating fluid passing through the fluid passage is prevented from being transmitted to the back side metal layer side. Therefore, the heat exchange efficiency can be further improved. In the case of providing a heat insulating layer, it may be employed for example ceramic thermal spraying, the.

By the way, in this invention, FC (gray cast iron) and FCD (ductile cast iron) generally used for casting are employable as a material of a back surface side metal layer, for example. As a material for the surface electrodeposited metal layer, nickel or a nickel-based alloy can be employed. On the other hand, while the said back surface side metal layer can be comprised from casting of an invar alloy, the said surface electrodeposition metal layer can be comprised from an iron-nickel alloy (invention of Claim 2 ). Invar alloys are known to have a very low coefficient of thermal expansion, and nickel-iron alloys are also sufficiently small to have a coefficient of thermal expansion similar to that of Invar alloys. Therefore, by adopting these, the coefficient of thermal expansion can be reduced as a whole mold, and the dimensional accuracy of the molded product can be increased.

According to the mold manufacturing method of the present invention, a groove is formed on the surface of the back side metal layer having a large thickness obtained by casting or shape processing from a steel material, and an extinguishing material is disposed in the groove. The surface electrodeposition metal layer is formed by electrodeposition, and then the disappearing material is removed to form the fluid passage, so that the resin molding die having the fluid passage integrally, The heat exchange efficiency between the fluid passing through the passage and the product surface is high, and the mechanical strength is excellent.

Enlarged vertical front view showing the main part of the mold, showing the basic configuration Perspective view of mold with product side (cavity side) facing up Diagram showing manufacturing process in sequence The 1st Example of the present invention is shown and a partial expansion longitudinal section front view of a metallic mold

(1) Basic Configuration Hereinafter, the basic configuration of the mold and the manufacturing method thereof will be described with reference to FIGS. In this basic configuration , for example, an unsaturated polyester resin (thermoplastic resin) such as SMC or BMC is used as a material, and three-dimensional resin molded products such as automobile parts, aircraft parts, bathtubs, etc. are heat and cool molded (pressed) It is applied to a mold for molding by molding or the like). The present invention can be widely applied to injection molds made of thermosetting resins such as acrylic resins, ABS resins, and polycarbonate resins.

First, with reference to FIG.1 and FIG.2, the structure of the metal mold | die 1 which concerns on a basic structure is described. As shown in FIG. 2, the mold 1 has a round shape that is slightly horizontally long in the left and right direction as a whole, and the center portion excluding the peripheral portion (flange portion) is upward in the drawing. It has a smooth curved surface shape that bulges gently. The upper surface in the figure of the mold 1 is the surface (cavity surface) that becomes the product surface.

As shown in FIG. 1, the mold 1 includes a surface electrodeposited metal layer 2 positioned on the front surface (upper side in the drawing) and a surface electrodeposited metal layer 2 disposed on the back surface (lower surface side in the drawing) side. In other words, it has a so-called two-layer structure with the back-side metal layer 3 having a larger thickness . Before Symbol surface conductive Chakukinzoku layer 2, for example, electrodeposited layer of nickel consists (electroplated layer) is formed with a thickness dimension of, for example, 3~5mm about. The back side metal layer 3 is formed, for example, by casting FC (gray cast iron) or FCD (ductile cast iron), and has a thickness dimension of, for example, about 20 to 30 mm. If the shape is relatively simple (simple), the back-side metal layer 3 can be formed not by casting but by shaping from a steel material.

  Then, a cooling or heating fluid (for example, water, steam, oil, etc.) is passed through the inside of the mold 1, that is, through the joint portion between the surface electrodeposited metal layer 2 and the backside metal layer 3. A large number of fluid passages 4 are formed. These multiple fluid passages 4 have a substantially semicircular cross section, and as shown in FIG. 2, a portion close to the surface of the mold 1 extends along the short side direction (front-rear direction in the figure). A plurality of them are formed in parallel. Although not shown, both front and rear ends of each fluid passage 4 are connected to fluid inlet / outlet portions provided on the front and rear sides of the bottom surface of the mold 1, respectively. The back side metal layer 3 and the surface electrodeposited metal layer 2 are joined at a portion where the fluid passage 4 does not exist.

  As will be described in detail below, the backside metal layer 3 is formed by casting, and the surface electrodeposited metal layer 2 is formed by electrodeposition (electroplating) on the surface of the backside metal layer 3. At this time, as shown also in FIGS. 3B, 3C, etc., the disappearance which can be removed by chemical or physical means in the groove 5 formed on the front surface side of the back side metal layer 3. In a state where the material 6 is arranged, the surface electrodeposited metal layer 2 is formed by electrodeposition so as to cover the surface of the backside metal layer 3 together with the extinguishing material 6, and then the extinguishing material 6 is removed. As a result, the fluid passage 4 is formed.

Next, a method for manufacturing the mold 1 will be described with reference to FIG. Figure 3 shows a schematic of the overall manufacturing process of the mold 1 in order. In manufacturing the mold 1, first, a metal layer forming process (casting process) is performed in which the back side metal layer 3 is formed by casting, for example. In this metal layer forming step, as shown in FIG. 3A, a mold (die casting mold) 7 corresponding to the shape of the back-side metal layer 3 (with a large thickness) is manufactured and melted in the mold 7. Pour metal material (FC) 8 and cool and harden. The mold 7 includes an upper mold 7a and a lower mold 7b.

  Next, when the metal material 8 in the mold 7 is cured, as shown in FIG. 3 (b), the back surface side metal layer 3 is taken out from the mold 7, and the primary shape processing (finishing) process on the surface ( And a groove forming step for forming the groove 5 to be the fluid passage 4 at a predetermined position on the front surface side of the back surface side metal layer 3 is performed.

  Next, as shown in FIG. 3C, a vanishing material attaching step of disposing (embedding) the vanishing material 6 in the groove 5 is performed. The vanishing material 6 is made of a material that can be removed by chemical or physical means such as dissolution, vaporization, and combustion. In this case, for example, wax or paraffin that can be removed by heating is used. As the vanishing material 6, other than that, low melting point alloy solder, synthetic resin, natural resin, or the like can be used.

  When the vanishing material attaching step is completed, an electrodeposition step is subsequently performed in which the surface electrodeposited metal layer 2 is formed by electroplating so as to cover the surface of the backside metal layer 3 together with the vanishing material 6. In this electrodeposition step, as shown in FIG. 3 (d), in this case, an anode 10 made of nickel is disposed in the plating tank 9, and the back-side metal layer 3 is disposed as a cathode. In the plating tank 9, for example, a known electrolytic solution 11 for nickel plating whose main composition is nickel sulfamate is stored in a state maintained at a predetermined pH and temperature.

  At this time, the backside metal layer 3 is pre-treated in advance (such as a conductive treatment for the surface (exposed surface) of the extinguishing material 6), and although not shown, the backside metal layer 3 Masking processing is performed to cover a portion such as the back surface that is not desired to be plated with an insulating material. In this state, a direct current flows between the anode 10 and the cathode (back side metal layer 3). Then, by an electrolytic reaction, metal (nickel) is deposited (electrodeposited) on the surface portion of the back-side metal layer 3 including the exposed surface of the extinguishing material 6, and electrodeposition is performed.

  By performing electrodeposition of a predetermined thickness (for example, 3 to 5 mm) on the surface of the backside metal layer 3 to form the surface electrodeposited metal layer 2, the electrodeposition process is completed, and the surface electrodeposited metal layer 2 The back side metal layer 3 on which is formed is taken out from the plating tank 9. In this state, as shown in FIG. 3 (e), the extinguishing material 6 is formed in a semicircular cross section formed between the surface electrodeposited metal layer 2 and the backside metal layer 3 (groove 5). Is embedded.

  Therefore, as shown in FIG. 3 (f), a removing step is performed in which the disappearable material 6 embedded in the groove 5 is dissolved and removed by chemical or physical means, in this case by heating. As a result, the disappearing material 6 is removed (disappeared), and the fluid passage 4 is formed. Thereafter, a finishing process (machining, polishing, etc.) is performed on the surface of the surface electrodeposited metal layer 2 and the mold 1 is obtained.

According to the mold 1 having such a basic configuration and its manufacturing method, the following actions and effects can be obtained. That is , the mold 1 has a two-layer structure of a surface electrodeposited metal layer 2 positioned on the front surface side and a back surface side metal layer 3 positioned on the back surface side and thicker than the surface electrodeposited metal layer 2. At this time, since the back surface side metal layer 3 is formed by casting (or shape processing from a steel material), it can be obtained easily and inexpensively, but can have a sufficiently large thickness. As the strength can be increased. As a result, sufficient mechanical strength can be obtained even when the mold 1 is used for compression molding (press molding).

  Moreover, the surface electrodeposition metal layer 2 on the front side becomes a dense metal layer obtained by electroplating (electrodeposition process), and even if the surface roughness of the back side metal layer 3 obtained by casting is rough. A sufficiently smooth and dense surface of the mold 1 can be obtained so as to cover the unevenness. The surface electrodeposited metal layer 2 has a high bonding strength with respect to the back-side metal layer 3 and can be relatively thin, so that it can be manufactured in a relatively short time. As a result, in addition to forming the back-side metal layer 3 by casting or the like, the manufacturing as a whole is easy and the manufacturing cost can be reduced.

  And the groove | channel 5 is formed in the surface side of the back surface side metal layer 3, and the surface of the back surface side metal layer 3 and the vanishing material 6 is covered in the state by which the vanishing material 6 was embedded in the groove | channel 5. A surface electrodeposited metal layer 2 is formed. As a result, a cavity filled with the vanishing material 6 is formed inside the mold 1, and the vanishing material 6 is removed, whereby the cavity becomes the fluid passage 4. Thereby, the fluid passage 4 having a small cross section can be formed to have an arbitrary shape. Moreover, since the fluid passage 4 is formed immediately outside the thin surface electrodeposited metal layer 2, the heat exchange efficiency between the cooling or heating fluid and the surface electrodeposited metal layer 2 is high, and the temperature adjustment performance is improved. Excellent and can easily cope with rapid heating and rapid cooling. Furthermore, the entire surface electrodeposited metal layer 2 can be uniformly cooled and heated, and the temperature distribution can be improved.

Thus, according to the mold 1 of the basic configuration, the resin molding mold 1 integrally having the fluid passage 4, and the efficiency of heat exchange between the fluid passing through the fluid passage 4 and the product surface Is excellent and mechanical strength is excellent. Moreover, according to the manufacturing method of the mold 1 having the basic configuration, the mold 1 having high heat exchange efficiency between the fluid passing through the fluid passage 4 and the product surface and excellent in mechanical strength is easily manufactured. Is something that can be done.

(2) First Example and Other Examples FIG. 4 shows a mold 21 according to a first example of the present invention. The first embodiment is different from the mold 1 having the above basic configuration in that a heat insulating layer 22 made of ceramic, for example, is provided on the surface including the inner surface of the groove 5 of the back surface side metal layer 3. .

Although illustration is omitted, when the mold 21 is manufactured, after performing the metal layer forming step (see FIG. 3A) and the groove forming step (see FIG. 3B) in the same manner as the above basic configuration . Then, a heat insulating layer forming step is performed in which the heat insulating layer 22 including the inner surface of the groove 5 is provided on the surface of the back side metal layer 3. This heat insulation layer formation process can be performed by thermal spraying of ceramics, for example. In the subsequent process of attaching the extinguishing material, the extinguishing material 6 is disposed in the groove 5 covered with the heat insulating layer 22.

  Furthermore, an electrodeposition process is performed in which the surface electrodeposited metal layer 2 is formed by electroplating so as to cover the surface of the backside metal layer 3 (heat insulating layer 22) together with the extinguishing material 6. In addition, a conductive treatment is performed on the surface (exposed surface) of the extinguishing material 6 and the surface (exposed surface) of the heat insulating layer 22 other than the groove 5 in advance. Thereby, in the electrodeposition process, the surface electrodeposited metal layer 2 having a predetermined thickness is formed on the exposed surface of the vanishing material 6 and the surface of the heat insulating layer 22 other than the groove portion 5. Thereafter, the disappearing material 6 is removed by a removal step, and the mold 21 is obtained by finishing treatment or the like.

According to the mold 21 and the manufacturing method thereof according to the first embodiment, the surface including the inner surface of the groove 5 of the back-side metal layer 3 can be obtained in addition to the same operation and effect as the basic configuration. By providing the heat insulating layer 22 on the surface, it is possible to suppress the heat of the cooling or heating fluid passing through the fluid passage 4 from being transmitted to the back surface side metal layer 3 side. The heat exchange efficiency between the electrodeposited metal layer 2 and the fluid can be further improved.

Next, although not shown, a second embodiment of the present invention will be described. The metal mold according to the second embodiment is different from the metal mold 1 having the above basic configuration in the materials of the back surface side metal layer 3 and the surface electrodeposited metal layer 2. That is, the back surface side metal layer 3 is composed of invar alloy (Fe-36% Ni) casting, and the surface electrodeposited metal layer 2 is composed of iron-nickel alloy electroplating. Among them, the back surface side metal layer 3 is obtained by pouring invar alloy dissolved in the mold 7 and cooling and hardening (metal layer forming step).

  And in the electrodeposition process (electroplating process) which forms the surface electrodeposition metal layer 2, as a plating solution 11 accommodated in the plating tank 9, for example, nickel sulfate or nickel sulfamate is made into a main composition, In addition to it For example, nickel chloride, ferrous sulfate (ferrous sulfamate), boric acid, an antioxidant, a stress reducing agent, a surfactant and the like are used. Thus, in the electrodeposition process, iron is co-deposited with nickel as an alloy, and the electrodeposited material on the surface of the back-side metal layer 3 is a nickel-iron alloy containing nickel and iron. In this case, the ratio of iron in the nickel-iron alloy is about 20 to 65% by mass.

Here, it is known that the Invar alloy has a very low coefficient of thermal expansion, and the back-side metal layer 3 can be made of a material having a low coefficient of thermal expansion. And the nickel-iron alloy which comprises the surface electrodeposition metal layer 2 has a sufficiently small thermal expansion coefficient (linear expansion coefficient) compared with what was obtained by electroforming of nickel, for example. Nickel-iron alloys are also excellent in hardness and tensile strength. Therefore, according to the second embodiment, the coefficient of thermal expansion can be reduced as a whole mold, and the dimensional accuracy of the molded product can be increased.

  In addition, as a material of the surface electrodeposition metal layer 2 and the back surface side metal layer 3 which comprise a metal mold | die, it is not limited to an above-described thing, It can also be set as another material, for example, nickel alloy (cobalt, An alloy of tungsten or the like and nickel) or another metal material such as copper or a copper alloy may be used. In addition, the mold can be used for various moldings. As described above, the metal forming step for forming the back-side metal layer 3 is not limited to casting, and shape processing (machining such as machining) from a steel material can also be employed. In addition, the present invention is not limited to the above-described embodiments. For example, the shapes of the molds 1 and 21, the thickness dimensions and balance of each part, the position where the fluid passage is provided, the cross-sectional shape of the fluid passage and the extending direction Various modifications (such as a meandering shape) can be made as appropriate without departing from the spirit of the invention.

  In the drawings, 1 and 21 are molds, 2 is a surface electrodeposited metal layer, 3 is a backside metal layer, 4 is a fluid passage, 5 is a groove, 6 is a disappearing material, and 22 is a heat insulating layer.

Claims (2)

Resin having a cooling or heating fluid passage between a surface electrodeposited metal layer whose surface constitutes a product surface and a backside metal layer disposed on the backside and having a thickness greater than that of the surface electrodeposited metal layer A method for producing a mold for molding,
A metal layer forming step of forming the back side metal layer by casting or shape processing from steel; and
A groove forming step for forming a groove to be the fluid passage on the front surface side of the backside metal layer;
After the groove forming step, a heat insulating layer forming step of thermally spraying a ceramic heat insulating layer on the entire surface of the back side metal layer including the inner surface of the groove;
A vanishing material attaching step of disposing a vanishing material removable by chemical or physical means in the groove covered with the heat insulating layer;
An electrodeposition step of forming the surface electrodeposited metal layer by electroplating so as to cover the surface of the backside metal layer together with the disappearing material;
And a removing step of forming the fluid passage by removing the vanishable material. The method for producing a mold according to claim 1, wherein the back side metal layer is made of an invar alloy, and the surface electrodeposited metal layer is made of an iron-nickel alloy.

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