JPH02225687A - Production of air permeable porous electroformed die - Google Patents

Abstract

PURPOSE:To produce an air permeable porous electroformed die having prescribed air vents by planting short fibers in the surface of a conductive film formed on the surface of a mandrel and applying electroforming to the film while growing air vents from the tips of the short fibers. CONSTITUTION:Epoxy resin, etc., are poured via an inlet 9b of a reinforcing member 9a onto an intermediate mold formed by using a model, by which a mandrel 9 having crimp pattern 8 is formed. A conductive film 10 is formed on the mandrel 9 surface by means of silver mirror reaction, etc., and short fibers 11 are planted in this conductive film 10 in the prescribed density. It is preferably that these short fibers 11 are nonconductive, and the diameter of fiber is regulated so that it corresponds to the diameter of an air vent. Subsequently, electroforming is applied to the above conductive film 10 surface to form a primary layer 12 of die in which respective tips of the above short fibers 11 are left. Electroforming is further performed, by which a secondary layer 14 of metal mold is laminated and formed on the above primary layer 12 of die while forming and growing air vents from respective short fibers 11 mentioned above. Then, the mandrel 9 is peeled off and the above short fibers 11 are removed, and an air permeable porous electroformed die 1 having the air vents 13 whose number and diameter are precisely controlled and reverse crimp pattern 15 can be obtained.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is used in vacuum forming, pressure forming, blow forming, stamping forming, roll forming, rim (RIM) forming, injection molding, and various other synthetic resin forming processes. The present invention relates to a method for manufacturing an electroforming mold, and specifically relates to an air-permeable porous electroforming mold equipped with ventilation holes for vacuum suction or compressed air.

[Prior art and problems to be solved by the invention] Most of the conventional permeable electroforming molds are non-porous electroforming molds formed by the -ffl electroforming method, and then a large number of holes are formed by drilling or laser processing. It is manufactured by forming ventilation holes.

However, with these processing methods, the diameter of the vent hole tends to become larger than necessary, and there is a risk that the vent hole will be transferred to the synthetic resin molded product. In addition, since the diameter of the vent hole was constant from the front surface to the back surface of the electroforming mold, there was a problem that the ventilation resistance was extremely high despite the large hole diameter, and the ability of vacuum suction or compressed air was reduced. .

Also, recently, breathable ceramic molds manufactured by molding and sintering ceramic powder, metal powder, etc. have been developed.

However, the ventilation holes of this breathable ceramic type were formed by intricately connecting gaps between ceramic powders and did not penetrate straight through, so there was still considerable ventilation resistance.

Therefore, in order to solve the above problems, the present inventor completed the invention of an air permeable porous electroforming mold which is made by generating and growing a large number of minute ventilation holes at the same time as electroforming. (Japanese Unexamined Patent Publication No. 152692/1983). The present invention relates to an improvement of this invention, and its purpose is to provide a method for manufacturing an air-permeable porous electroforming mold in which the number and diameter of ventilation holes can be easily and accurately controlled.

1 Means for Solving the Problems J In order to achieve the above object, the method for manufacturing a breathable porous electroforming mold of the present invention includes a step of forming a mandrel, a step of forming a conductive film on the surface of the mandrel, a step of flocking short fibers on the surface of the conductive coating; a step of electroforming the surface of the conductive coating to form a first layer of a mold in which the short fibers are buried leaving their tips; a step of laminating and forming a second layer of the mold while generating and growing vent holes from the tips of the short fibers by electroforming on the surface of the first layer of the mold; The method consisted of a step of peeling the two layers from the mandrel, and a step of removing the short fibers from the first layer of the mold.

[Function] The portion where the short fibers are buried in the first layer of the mold is a portion that opens as a ventilation hole when the short fiber is removed, so it can be said that a ventilation hole has potentially occurred. Therefore, the number of short fibers determines the number of ventilation holes formed in the air-permeable porous electroforming mold, and the diameter of the short fibers determines the diameter of the ventilation holes opened on the surface of the gas-permeable porous electroforming mold.

When electroforming is performed on the surface of the first layer of the mold, the electroformed metal is electrodeposited on the surface to form the second layer of the mold, but is not electrodeposited on the tips of the short fibers. Therefore, at the tip of this short fiber, a vent hole that is connected to the vent hole that was potentially generated in the previous process is generated as a secondary step. direction and penetrate the second layer of the mold.

After the first layer of the mold and the second layer of the mold are peeled off from the mandrel, short fibers are removed from the first layer of the mold to open the ventilation holes and complete a breathable porous electroforming mold.

[Example] Hereinafter, examples embodying the present invention will be described with reference to FIGS. 1 to 12. This example relates to a method for manufacturing a breathable porous electroforming mold 1 having ventilation holes 13 as shown in FIGS. 11 and 12, and includes the following steps.

(1) As shown in Fig. 1, after forming a model 2 with the same shape as the desired synthetic resin molded product from wood, synthetic resin, plaster, wax, and other various materials, as shown in Fig. 2, IR#1
A master model 5 is formed by pasting cowhide, suede, cloth, or other pattern-imparting material 4 having a grain pattern 3 on the surface of the model 2.

In this example, cowhide was used.

(2) As shown in FIG. 3, by injecting silicone rubber or other low-adhesive material onto the surface of the master model 5 and curing it (the injection frame etc. are shown), the group grain pattern is created. An intermediate mold 7 having a secondary reverse grain pattern 6 formed by transferring 3 is formed, and the intermediate mold 7 is peeled off as shown in FIG.

(3) As shown in FIG. 5, a reinforcing member 9a made of iron, aluminum, etc. is applied to the surface of the intermediate mold 7 with a gap left therebetween. Then, by injecting an epoxy resin or other reactive hardening material into the gap through the injection hole 9b provided in the reinforcing member 9a and curing it, a tertiary grain pattern is formed by transferring the secondary reverse grain pattern 6. 8 is formed, and the mandrel 9 is peeled off as shown in FIG.

(4) As shown in FIG. 7, a thin conductive film 10 is deposited on the surface of the mandrel 9.

Examples of methods for forming the conductive film 10 include silver mirror reaction, spray application of paste silver lacquer, electroless plating, vapor deposition plating, and the like.

Further, the thickness of the conductive film 10 is preferably 5 to 30 μm, because if it is too thin, sufficient conductivity will not be obtained, and if it is too thick, the fidelity of the tertiary grain pattern 8 will be reduced.

(5) As shown in FIG. 8, short fibers 11 are planted on the surface of the conductive coating 10.

Examples of the short fibers 11 include natural fibers, chemical fibers, glass fibers, and ceramic fibers. The material of the short fibers 11 is preferably non-conductive so that electroformed metal is not electrodeposited on the tips of the short fibers 11 in the next electroforming step. In addition, since the short fibers 11 are removed in the final removal step and replaced with ventilation holes 13 to be described later, the short fibers 11 are removed in order to facilitate this removal.
Preferably, the material 1 has a melting point or ignition point lower than the melting point of the electroformed metal described later, or a material that can be dissolved in a solvent (a solvent in which cast metal does not dissolve).

The number of short fibers 11 determines the number of vent holes 13 formed in the breathable porous electroforming mold 1 (total number of vent holes 13 and number per unit area). Therefore, by appropriately determining the number of these short fibers 11 according to the size of the breathable porous electroforming mold 1, the fineness of the original grain pattern 3, etc., the ventilation holes 13
can be set exactly to the desired number. Also,
By not flocking the short fibers 11 to a portion of the mandrel 9, it is also possible to form a portion of the air-permeable porous electroforming mold 1 without the ventilation holes 13.

Furthermore, the diameter of the short fibers 1 determines the diameter of the ventilation holes 13 that open on the surface of the air-permeable porous electroforming mold 1. Therefore, by selecting the diameter of the short fibers 11, it is possible to easily and accurately form vent holes ranging from a hole diameter of 1 to 30 μm, which is extremely difficult to process using conventional methods, to a hole diameter of about 500 μm.

Further, the length of the short fibers 11 is longer than the thickness of the first layer 12 of the mold to be formed in the next step, and is 2 times the diameter of the short fibers 11.
There is no particular limitation as long as it is shorter than 0 times, but it is 2 to 10 times the diameter.
twice is common.

As a method for flocking the short fibers 11, various known electrostatic flocking methods can be employed. For example, connect the positive electrode (as shown) to the conductive liquid WA10 of the mandrel 9 facing downward, place the short fiber 11 on the negative electrode (as shown) facing downward, and apply a high DC voltage to the picture electrode. For example, the short fibers 11 are drawn upward and the conductive coating 10
Attach perpendicular to. At this time, an adhesive may be thinly applied to the conductive coating 10 in advance, and the short fibers 11 may be adhered to the adhesive, but the tertiary grain pattern 6 may be attached by an amount corresponding to the thickness of the adhesive.
fidelity is reduced. Therefore, a chemical fiber or the like having a low melting temperature is used for the short fibers 11, and the mandrel 9
It is also preferable to heat the conductive film 10 to a higher temperature than the melting temperature of the short fibers 11 and heat-weld the short fibers 11 directly to the conductive film 10.

(6) As shown in FIG. 9, electroforming is performed on the surface of the conductive coating 10 to form a mold first layer 12 in which the short fibers 11 are buried, leaving only their tips.

As the electroforming method in this step, an electroforming method comprising a known general electroforming metal, electroforming bath, and electroforming conditions can be adopted. In this example, the mandrel 9 and the nickel electrode (as shown) as the electroformed metal are immersed in an electroforming bath mainly composed of nickel sulfamate, boric acid, and a surfactant for suppressing pinholes. General electroforming was performed by applying a DC voltage between the conductive film 10 (cathode) and the nickel electrode (anode).

The portion where the short fibers 11 are buried in the mold first layer 12 is the portion that opens as the ventilation hole 13 when the knowledge till is removed, so it can be said that no ventilation hole is potentially generated. Note that no unplanned ventilation holes other than the ventilation holes 13 are generated in the first layer 12 of the mold. That is, according to the present invention, the formation of the ventilation holes 13 can be completely controlled.

(7) As shown in FIG. 10, by performing electroforming on the surface of the first layer 12 of the mold, the vent holes 13 are secondarily generated and grown from the tips of the short fibers 11, and the metal mold is A second mold layer 14 is laminated.

The electroforming in this process differs from the known general electroforming method in that a special electroforming bath that does not contain a surfactant to suppress pinholes is used, and the electroforming conditions are changed as necessary. Now, the mandrel 9 and the nickel electrode (as shown) as the electroformed metal are immersed in an electroforming bath containing nickel sulfamate and boric acid as main components and containing no surfactant, and the conductive coating 10 (cathode) and the electroforming bath are immersed in the bath. Nickel electrode (anode)
Electroforming was performed by applying DC voltage between the two. Further, although the current was small at the beginning of electroforming and increased from the middle, it is not limited to this.

In this step, the electroformed metal is electrodeposited on the surface of the first layer 12 of the mold, but not on the tips of the short fibers 11. Therefore, vent holes 13 are secondarily generated at the tips of the short fibers 11, which are continuous with the vent holes potentially generated in the previous step. Since the electroforming bath or the electroforming conditions promote the growth of the vent holes 13, the vent holes 13 grow in the electrodeposition direction as the electroforming progresses without being blocked midway, and the mold second layer 14 penetrate. At this time, the diameter of the vent hole 13 expands as it grows, but the manner and extent of the diameter expansion are t.
It can be freely controlled by changing the casting conditions.

(8) As shown in FIG. 11, when the first mold layer 12 and the second mold layer 14 are peeled off from the mandrel 9 and the conductive coating 10 is attached to the first mold layer 12, The conductive coating 10 is removed chemically or physically.

(9) Finally, as shown in FIG. 11, the short fibers 11 are removed from the mold first layer 12 to open the ventilation holes 13, thereby completing the breathable porous electroforming mold 1.

Examples of methods for removing the short fibers 11 include a method of dissolving the short fibers 11 with a solvent, a method of burning the short fibers, and a method of softening the short fibers with a solvent or heating and extruding them using air pressure.

As shown in FIG.
A quaternary reverse grain pattern 15 is formed by transferring. Further, according to the present invention, by controlling the number of ventilation holes 13, one or more ventilation holes 13 can be formed for each pattern unit of the quaternary grain pattern 15. Therefore, this breathable porous electroforming mold 1 can be used, for example, to perform vacuum forming, vacuum pressure forming, stamping molding, or roll forming of synthetic resin sheets, blow molding of synthetic resin parisons, rim forming or When molding various synthetic resins such as injection molding, the quaternary grain pattern 15 can be transferred to the synthetic resin molded product in detail to form a highly faithful tertiary grain pattern (as shown).

Furthermore, since the diameter of the vent hole 13 that opens on the surface of the breathable porous electroforming mold 1 can be made very small,
There is no fear that the vent hole 13 will be transferred to the synthetic resin molded product. Further, since the diameter of the vent hole 13 gradually increases from the mold second layer 14, the ventilation resistance due to the vent hole 13 is low, and there is no fear that the ability of vacuum suction or compressed air will deteriorate.

Next, a backup example of the air permeable porous electroforming mold 1 will be described with reference to FIGS. 13 to 15. In each backup example, a support frame 16 is attached around the back side of the breathable porous electroforming mold 1, and a bottom plate 17 is attached to the lower end of the support frame 16. The support methods are different.

In the example shown in FIG. 13, support plates 18 that follow the shape of the back surface of the breathable porous electroforming mold 1 are assembled vertically and horizontally within a support frame 16, and the support plates 18 are provided with air holes 19. There is.

In the example shown in FIG.
is fixed to and supported by a reinforcing plate 21 attached within the support frame 16. Furthermore, the cooling chamber 22 formed between the breathable porous electroforming mold 1 and the reinforcing plate 21 is filled with a fibrous body 23, and cooling water is supplied from below the reinforcing plate 21 to the cooling chamber 22. Air is vacuum-suctioned together with cooling water to enable forced cooling of the porous electroforming mold 1 (Japanese Patent Application No. 62-270045).
.

In the example shown in FIG. 15, metal granules 24 are filled on the back side of the air-permeable porous electroforming mold 1, and mutually contacting parts of the metal granules 24 are bonded with a metal bonding material (Japanese patent application No. 6
2-335707).

It should be noted that the present invention is not limited to the configuration of the above-mentioned embodiments, and may be modified and embodied as desired without departing from the spirit of the invention, for example, as described below.

(1) The surface of the mandrel 9 may be a mirror surface without a pattern. In this case, the surface of the breathable porous electroforming mold 1 also becomes a mirror surface, and the vent holes 13 improve the transferability of the mirror surface.

(2) The method for forming the mandrel 9 is not limited to the steps of the above embodiments, and can be formed by various known methods.

(3) The air-permeable porous electroforming mold l produced according to the present invention can be used as a mold for various synthetic tM# moldings, and is not limited to a specific molding method.

[Effects of the Invention] Since the method for manufacturing an air-permeable porous mold of the present invention is configured as described above, the number and diameter of the ventilation holes can be easily and accurately controlled. However, it has an excellent effect of being easily formed.

[Brief explanation of the drawing]

Figures 1 to 12 show an embodiment of the method for manufacturing a breathable porous electroforming mold embodying the present invention, Figure 1 is a sectional view of the model, Figure 2 is a sectional view of the master model, and Figure 3 is a sectional view of the master model. Figure 4 is a cross-sectional view of the intermediate mold formed by injecting silicone rubber into the master model, and Figure 5 is a cross-sectional view of the intermediate mold formed by injecting epoxy resin into the intermediate mold. FIG. 6 is a cross-sectional view of the mandrel, FIG. 7 is a cross-sectional view when a conductive film is formed on the mandrel, FIG. 8 is an enlarged cross-sectional view when short fibers are implanted on the mandrel, and FIG. Figure 9 shows the first layer of the mold on the conductive film! FIG. 1.0 is an enlarged cross-sectional view of the mold after forming the mold by electroforming, FIG. FIG. 12 is an enlarged partial perspective view of the porous electroforming mold. FIG. 12 is a partially enlarged perspective view of the porous electroforming mold. FIG. 13 is a sectional view showing an example of the buffer chamber of the permeable porous electroforming mold, FIG. 14 is a sectional view showing another backup example, and FIG. 15 is a sectional view showing still another backup example. DESCRIPTION OF SYMBOLS 1... Breathable porous electroforming mold, 9... Mandrel, 10... Conductive coating, 11.
...short fiber, 12...mold first layer 13...
・Vent hole, 14...Mold second layer.

Claims (1)

[Claims] 1. A step of forming a mandrel (9), and a step of forming a conductive film (10) on the surface of the mandrel (9),
A step of implanting short fibers (11) on the surface of the conductive coating (10), and electroforming the surface of the conductive coating (10) so that the short fibers (11) are buried with their tips remaining. The short fibers (
11) forming and laminating a second mold layer (14) while generating and growing a vent hole (13) from the tip of the mold, and forming the first mold layer (12) and the second mold layer (14). from the mandrel (9), and peeling off the mold from the first layer (1).
2) A method for manufacturing an air-permeable porous electroforming mold, which comprises the step of removing the short fibers (11) from the mold.