JPH1044161A - Manufacture of epoxy resin mold and epoxy resin mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent mold surface layers from expanding and contracting and ply separation and crack on the mold surface layer from occurring by a method wherein expansion and contraction blocking parts for preventing the mold surface layers from expanding to and contracting from lining layers are provided on the mold surface layers of the lining layers. SOLUTION: This epoxy resin mold 1 consists of a cavity side epoxy resin mold 10 and a core side epoxy resin mold 20. Both the molds consists respectively of mold surface layers 11 and 21 and lining layers 12 and 22. When both the molds are set, a space P, which is equal to the shape of an object product, is formed between both the mold surface layers 11 and 21. The lining layers are respectively equipped with cooling pipes, epoxy resin pouring pipes 14 and 24 and resin discharging pipes 15 and 25. With epoxy resins respectively forming the mold surface layers 11 and 21, a metal powder, the thermosetting shrinkage of which is small and the thermal conductivity of which is high, is mixed. On the lining layers 12 and 22, lattice-like projected bead expansion and contraction holding parts 16 and 26 are provided. As a result, the mold surface layer and the lining layer join favorably to each other and there is no fear of developing crack or ply separation.

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 an epoxy resin mold and an epoxy resin mold used for trial production of various molded products, and more particularly, to delamination between a mold surface layer and a backing layer. The present invention relates to an epoxy resin mold manufacturing method and an epoxy resin mold which are free from cracks and air bubbles in a mold surface layer.

[0002]

2. Description of the Related Art Conventionally, an epoxy resin mold has been used for molding a small amount of a molded product such as a prototype. The epoxy resin mold includes a mold surface layer that directly contacts a molded product and a backing layer that supports the mold surface layer. The mold surface layer is formed of epoxy resin, and the backing layer is formed of a metal member.

However, the mold surface layer may delaminate from the backing layer due to curing shrinkage of the epoxy resin during the production of the resin mold, expansion or contraction of the mold surface layer with respect to the backing layer due to heating, cooling, or the like during use. In addition, there is a problem that cracks occur. In addition, since the mold surface layer is formed by injecting a mixture of an epoxy resin and a metal powder into the backing layer under atmospheric pressure, air bubbles are generated between the surface of the mold surface layer, the inside, and the interlayer between the backing layer. Entrapment creates air pockets, which also cause peeling and cracking. For the mold surface layer, it is desirable to increase the mixing ratio of the metal powder to improve the thermal conductivity.However, if the mixing ratio of the metal powder is increased, the adhesion to the backing layer is reduced, and delamination is more likely to occur. Problem.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and the invention according to claims 1 to 3 has been described above. An object of the present invention is to provide a method for producing an epoxy resin mold that does not cause cracks in the surface layer and does not cause air pockets.

[0005] The invention according to claim 4 is based on claim 1.
Another object of the present invention is to provide a method of manufacturing an epoxy resin mold that can be easily cast even with a thin mold surface layer having a thickness of 15 mm or less, in addition to the objects of the inventions described in 3 to 3.

It is an object of the present invention to provide an epoxy resin mold which does not cause delamination between the mold surface layer and the backing layer and does not cause cracks in the mold surface layer.

[0007]

According to the present invention, there is provided a method of manufacturing an epoxy resin mold according to the present invention, wherein the mold surface layer is formed of a mixture of an epoxy resin and a metal powder. A method for producing an epoxy resin mold, wherein a backing layer formed of a metal and a backing layer in close contact with the mold surface layer is formed on the mold surface layer side of the backing layer to prevent expansion and contraction of the mold surface layer with respect to the backing layer. A backing layer casting step of forming a backing layer provided with a stretch prevention portion, and a mold surface layer casting step of forming a mold surface layer by injecting the mixture into the backing layer under vacuum. Features.

[0008] The expansion and contraction of the mold surface layer with respect to the backing layer means the shrinkage of the mold surface layer during the production of the resin mold and the heating during the use of the resin mold, assuming that no binding force acts between them. The displacement of the mold surface layer with respect to the backing layer caused by the difference between expansion and contraction due to cooling. And, the expansion / contraction preventing portion for preventing expansion / contraction is provided on the mold surface layer side of the backing layer, and the ridges, concave stripes, independent protrusions or concave portions, which restrict the mold surface layer so that the expansion / contraction does not occur, are continuous. Or a combination thereof. That is,
The expansion / contraction preventing portion referred to here is intentionally formed on the mold surface layer side of the backing layer, and does not include minute irregularities which are naturally formed corresponding to the sand grains of the sand mold.
However, irregularities having a depth or width of 1 mm or more using a sand mold made of large-sized sand that is not usually used are included in the above-mentioned expansion / contraction preventing portion. Injecting the mixture into the backing layer under vacuum means injecting the mixture in a state where at least the container in which the mold for forming the backing layer and the mold surface layer is set is evacuated. Thereby, the resin flows into the base of the expansion / contraction preventing section having the complicated shape as described above.

The epoxy resin forming the mold surface layer preferably has a low thermal curing shrinkage and has excellent mechanical strength. As the metal powder, generally, a metal powder having a high thermal conductivity is desirable, but an aluminum powder is most desirable. The mixing ratio between the epoxy resin and the metal powder varies depending on the type of the metal powder, but it is preferable that the weight of the metal powder is 70% or more with respect to the epoxy resin. The backing layer may be made of metal, but is desirably formed of a zinc alloy having a thermal expansion coefficient substantially equal to that of epoxy resin.

According to a second aspect of the present invention, in the method for manufacturing an epoxy resin mold according to the first aspect, the expansion / contraction preventing portion formed in the backing layer casting step is formed entirely on the mold surface layer side of the backing layer. It is characterized by the crossing stripes arranged. Intersecting ridges prevent expansion and contraction in any direction.

According to a third aspect of the present invention, in the method for manufacturing an epoxy resin mold according to the second aspect, the ridge portion is a convex ridge.

According to a fourth aspect of the present invention, in the method for manufacturing an epoxy resin mold according to any one of the first to third aspects, the mold surface layer casting step includes heating the mixture and lining the heated mixture with the backing. A first step of injecting the layer under vacuum to form a mold surface layer, a second step of forcibly cooling the mold surface layer and then curing the mold surface layer at room temperature, And a third step of heating and curing the layer.

The epoxy resin mold of the invention according to claim 5 is
A mold surface layer formed of a mixture of an epoxy resin and a metal powder, and a metal backing layer in close contact with the mold surface layer, and a mold surface layer for the backing layer on the mold surface layer side of the backing layer. It is characterized in that it is provided with an expansion / contraction preventing portion for preventing expansion / contraction.

According to a sixth aspect of the present invention, in the epoxy resin mold according to the fifth aspect, the expansion / contraction preventing portion formed in the backing layer casting step is disposed entirely on the mold surface layer side of the backing layer. Characterized in that they are crossing strips.

According to a seventh aspect of the present invention, in the invention of the sixth aspect, the cross section of the ridge portion has a hook shape which is difficult to remove.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory view of an epoxy resin mold of the present invention. FIG. 1 (a) is a cross-sectional view of the entirety, and FIG. 1 (b) is a partially enlarged view of an adhesion surface between a mold surface layer and a backing layer. is there. In FIG. 1A, an epoxy resin mold 1
Consists of an epoxy resin mold 10 on the cavity side and an epoxy resin mold 20 on the core side. Both are the mold surface layer 11,
21 and backing layers 12 and 22 provided in close contact therewith
When both are set, a space P between the mold surface layer 11 and the mold surface layer 21 equal to the shape of the desired target product is formed.
Is formed. Each of the backing layers 12 and 22 includes cooling pipes 13 and 23, epoxy resin injection pipes 14 and 24, and epoxy resin discharge pipes 15 and 25.

The epoxy resin forming the mold surface layers 11 and 21 is preferably one having a small thermal curing shrinkage and excellent in mechanical strength, and a metal powder generally having a high thermal conductivity is preferable, but an aluminum powder is preferable. Most desirable. The mixing ratio between the epoxy resin and the metal powder varies depending on the type of the metal powder, but it is preferable that the weight of the metal powder is 70% or more with respect to the epoxy resin. The backing layers 12 and 22 may be made of metal,
It is desirable to form a zinc alloy having a thermal expansion coefficient substantially equal to that of the epoxy resin.

Die surface layers 11 and 21 of backing layers 12 and 22
Each of the contact surfaces on the side is provided with ridges 16 and 26 arranged in a lattice shape as an example of expansion and contraction preventing portions 16 and 26 for preventing expansion and contraction of the mold surface layers 11 and 21 with respect to the backing layers 12 and 22. FIG. 1 (a) shows a cross section thereof.

FIG. 7 is a conceptual illustration of the operation of the ridge. FIG. 7A is a partially enlarged cross-sectional view of the resin mold of the present invention, and shows an enlarged close contact surface between the mold surface layer 71 and the backing layer 72. In this example, the ridges 77 are formed in a rectangular column shape, and a plurality of ridges 77 are arranged in parallel. FIG. 7B is a partially enlarged view of a conventional resin mold, and shows an enlarged contact surface between the mold surface layer 61 and the backing layer 62.

In FIG. 7B, the contact surface Sa between the mold surface layer 81 and the backing layer 82 is flat. For example, considering the case where the mold surface layer 81 contracts with respect to the backing layer 82, an internal stress σ ₁ that tends to contract is generated almost uniformly throughout the mold surface layer 81 inside the mold surface layer 82, and this is caused by close contact. On the surface Sa, it acts as a shear stress.
When the adhesion between the mold surface layer 81 and the backing layer 82 is smaller than this, delamination occurs. Further, when the difference is small even if the adhesion force is larger, delamination occurs when some external force is applied. In addition, if the internal stress is locally concentrated for some reason such as local peeling, peeling or cracking may further occur.

On the other hand, in the case of the resin mold shown in FIG. 7A, the internal stress σ ₂ (σ ₂₁
, σ ₂₂ ... σ ₂₇ ) are the ridges 77 (77a, 77b, 7).
7c, because it is blocked by 77d), the region, slightly different, the contact surface Sb of the mold surface layer 71 Anyway the backing layer _{72 (Sb 1, Sb 2 ···} S
Since the shear stress acting on b ₇ ) is much smaller than that of FIG. 7B, no delamination occurs. Even if partial separation occurs, propagation of the internal stress is blocked by the ridges 77, so that local concentration of the internal stress is prevented.

In the above example, the mold surface layer 7 of the backing layer 72
The case where a plurality of ridges are arranged in parallel on one side has been described. However, when the ridges 77 are arranged so as to intersect the whole, expansion and contraction in multiple directions in the contact plane is prevented, so that more effect is obtained. is there. Also, as described with reference to FIG. 1A, when the ridges 77 are arranged in a lattice, expansion and contraction in all directions in the contact plane are prevented, and the internal stress is evenly dispersed.
More effective.

In the examples shown in FIGS. 1A and 7A, the cross section of the ridge is rectangular, but the cross section of the ridge is not limited to this. FIG. 1B is a partially enlarged view of another embodiment, in which the close contact surface between the mold surface layer 11 and the backing layer 12 of the epoxy resin mold 10 on the cavity side is enlarged. On the mold surface layer side of the backing layer 12, irregularities 18 which are continuous with the ridges 17 as spots for preventing expansion and contraction are formed.
Are formed in a hook shape which is inflated more than the base portion 17b.

As described above, when the protrusion 17 is formed into a hook shape and the resin mixture is also filled into the base thereof, the expansion and contraction of the mold surface layer 11 in the thickness direction is prevented.
The effect of preventing delamination with the backing layer 12 and cracks is further enhanced.

Further, when the unevenness 18 continuous in the form of spots is provided, this also prevents expansion and contraction and concentration of internal stress, thereby further increasing the effect of preventing delamination and cracking. In addition, the continuous irregularities here are not minute irregularities which are naturally formed corresponding to the sand grains of the sand mold as described above, but are made of sand having a large particle diameter which is not normally used. 1m depth of unevenness using sand mold
m or more.

As described above, the example in which the backing layer is provided with the ridges and the example in which the ridges are combined with the irregularities continuous in the form of spots are described as the expansion / contraction portions. Naturally, various combinations thereof are also included in the present invention. In addition, the cross-sectional shape of the expansion / contraction preventing portion is not limited to a rectangular shape, a hook shape, a spot shape, or the like.

Next, a method of manufacturing the epoxy resin type backing layer according to the present invention will be described with reference to FIGS. FIG. 2 shows a process of molding the backing layer 12 of the epoxy resin mold 10 on the cavity side. FIGS. 2 (a) and 2 (b)
The production process of the reversal model by gypsum is shown. In FIG. 2A, first, a master model M2 having a shape on the outer surface side of a product to be molded is prepared. A sheet wax 11w is formed thereon in the same shape as the mold surface layer 11, which is surrounded by a mold frame (not shown), and gypsum mixed with water is poured and cured. Then, after curing, the mold is released to obtain a gypsum reversal model 30 shown in FIG. When the sand mold 40 is cast into the gypsum reversal model 30 as shown in FIG. 3C and the mold is released, the sand mold corresponding to the backing layer having a smooth surface before providing the expansion preventing portion 16 on the contact surface. 40 (hereinafter referred to as "pre-mold").

FIG. 3 shows a backing layer 1 provided with an expansion preventing portion 16 for preventing expansion and contraction from the pre-mold 40 on the mold surface layer side.
FIG. 4 is an explanatory diagram of a process of manufacturing a mold for manufacturing the second mold (hereinafter, referred to as “main mold”). FIG. 3A shows the pre-mold 4
0, a groove 42 having an inverted shape of the expansion / contraction preventing portion 16
FIG. 4 is a cross-sectional view of the present mold 41 in which is formed, and FIG.
3A shows a cross section. FIG. 1B is a plan view. The illustrated example is a mold for forming the expansion / contraction preventing portion 16 comprising the ridges 17 and the continuous irregularities 18 arranged in a lattice on the mold surface layer 11 side of the backing layer 12, and the grooves 42 are arranged in a lattice. The inverted shape of the provided ridge 17 is adopted. The groove 42 which is the inverted shape of the ridge 17 can be easily manufactured simply by cutting it with a cutter or the like.

3 (c) and 3 (d) are partially enlarged views of the pre-mold 40. FIG. 3 (c) is a partially enlarged plan view of FIG. 3 (b), and FIG. It is B sectional drawing. The width w of the groove 42 which is the inverted shape of the ridge is 2-3 mm, and the depth d is 3 ~.
It is preferably about 4 mm, but is not limited to this. When the ridge 17 is to be formed into a hook shape as shown in FIG.
a and an undercut portion 42a and a constricted portion 42b corresponding to the base portion 17b. Further, spot-like continuous irregularities 43 which are inverted shapes for forming the continuous irregularities 18 are formed.
Is preferably 1 mm or more in both width and depth. The irregularities 43 can be formed only by pressing or scraping the sand mold surface with an appropriate tool. In forming the continuous irregularities 43, the sand used for the sand mold was No. 6 (0.212 to 0.212).
0.425 μ). In the above example, this mold was a sand mold, but is not limited to this.
A plaster mold or a ceramic mold is also used.

FIG. 4 is a view showing a process of casting the backing layer 12 using the main mold 41. As shown in FIG. As shown in FIG. 4A, the mold 41 is surrounded by a mold frame (not shown), and the epoxy resin injection pipe 14, the epoxy resin discharge pipe 15, the cooling pipe 13 and the like are set at predetermined positions. Pour the molten metal, cool and solidify. Next, as shown in FIG. 1B, the mold is released, and the backing layer 12 is obtained. The backing layer 12 and the master model M2 are set as shown in FIG. 3 (c), an epoxy resin mixture is injected under vacuum, and the epoxy resin mixture is cured to form the mold surface layer 11. The resin mold 10 is completed. In the epoxy resin mold 10 thus obtained, the adhesion between the mold surface layer 11 and the backing layer 12 is improved by the expansion and contraction preventing portions 16 and the epoxy resin mold 10 is cast under a vacuum, so that air accumulation does not occur.

When it is desired to form a concave stripe on the contact surface of the backing layer with the mold surface layer, for example, the following manufacturing method is used. The manufacturing process up to the pre-mold 40 is the same as the process of casting the backing layer having the expansion / contraction preventing portions 16 described with reference to FIG. 2, and FIG. 8 shows the subsequent manufacturing process. First, a foamed polystyrene string 52 having an inverted shape of a concave streak to be formed on a backing layer is attached to the pre-mold 40, and a main mold 51 having a cross section as shown in FIG. Although a plan view is omitted, it is assumed that the strings 52 of expanded polystyrene are arranged in a lattice shape, for example.

Next, as shown in FIG.
1 is surrounded by a mold frame (not shown), and an epoxy resin injecting pipe 84, an epoxy resin discharging pipe 85, a cooling pipe 83 and the like are set at predetermined positions, and then a molten zinc is poured, cooled and solidified. Then, as shown in FIG. 3C, the main mold 51 is released from the mold, and a backing layer 82 is obtained.
In addition, the expanded polystyrene string 52 is
If it remains on 6, remove it.

The backing layer 82 and the master model M2 are set as shown in FIG. 3D, and an epoxy resin mixture is injected under vacuum and cured to form a mold surface layer 81.
When the mold is removed, the cavity-side epoxy resin mold 80 is completed. The epoxy resin mold 80 thus obtained is also prevented from expanding and contracting between the mold surface layer 81 and the backing layer 82 by the concave portions 86, and is cast under vacuum, so that no air pool is generated.

In the above-described embodiment, the ridges and recesses arranged mainly in a lattice shape have been described. However, the expansion / contraction preventing portion is not limited to this. Non-equidistant, non-parallel, intersecting at various angles, parallelly arranged in one direction, partially intersecting, and the like are included. In addition, the expansion / contraction preventing section is not limited to the convex ridge and the concave ridge, and includes an independent convex or concave section, continuous concave and convex sections, or a combination thereof. Further, the expansion / contraction preventing portion is not limited to the one provided on the entire contact surface, and the one provided partially is also included.

In the above-described method of manufacturing an epoxy resin mold, the casting step of the mold surface layers 11, 21 and 81 will be described in detail, typically for the mold surface layers 11 and 21.
First, as shown in FIG. 5A, using a product M1 having the same shape as a target product to be molded, a material such as wood or chemiwood is processed in accordance with the product, thereby producing a master model M2.

Next, the backing layers 12, 22 prepared earlier
(In the following description, the illustration of the expansion / contraction preventing portions 16 and 26 is omitted for convenience.) The lower surface 12a of the backing layer 12 has a space between the upper surface M2a of the master model M2 and the same shape as the desired mold surface layer. It has a shape as formed.

The epoxy resin has a small thermosetting shrinkage,
Those having excellent mechanical strength are desirable, for example, MYX-04, MYX-05, MYX- manufactured by Mitsubishi Yuka Corporation.
06 or the like is used. Generally, a metal powder having a high thermal conductivity is desirable, but as a result of various studies, an aluminum powder is most desirable. The mixing ratio between the epoxy resin and the metal powder varies depending on the type of the metal powder, but it is preferable that the weight of the metal powder is 70% or more with respect to the epoxy resin.
If it is less than 0%, the thermal conductivity will be insufficient.

A mixture E obtained by mixing a metal powder such as an aluminum powder into an epoxy resin is put into a heating oven G, and the temperature in the heating oven G is adjusted to 35 to 60 ° C. by a heater H and heated. After the viscosity of the epoxy resin mixture E is reduced by heating, the epoxy resin mixture E is taken out of the oven G and stirred using a suitable stirrer to uniformly disperse the metal powder. further,
The curing agent was mixed at a predetermined blending ratio, heated again to 35-60 ° C. in the oven G, and then stirred with a suitable stirrer,
Stir until homogeneously mixed. Then, the oven G containing the uniformly mixed epoxy resin mixture E is evacuated by the vacuum pump V to remove bubbles contained in the epoxy resin mixture E. In the case of an epoxy resin mixed with aluminum powder, the weight of the aluminum powder is 70% or more of the epoxy resin. If it is less than 70%, the thermal conductivity is insufficient, and if it is too large, the mechanical strength is reduced.
It is preferably about -76%.

Next, as shown in FIG.
Into the oven G, heated to 35 to 60 ° C., and then set on the master model M2. The inside of the oven G is evacuated again, the epoxy resin mixture E is injected from the hoppers F, F through the epoxy resin injection pipes 14, 14 of the backing layer 12, and the epoxy resin resin is discharged from the epoxy resin mixture discharge pipe 15. Fill until mixture E overflows. (The above is the first step).

Next, when the filling of the epoxy resin mixture E is completed, the epoxy resin mold 10 being formed is taken out of the vacuum box (heating oven) G as shown in FIG.
Cooling water W is passed through the cooling pipe 13 to forcibly cool the epoxy resin mold to room temperature. Next, the cooled resin mold 10 is placed in an oven G as shown in FIG. 5D and left at room temperature for 12 hours to temporarily cure the mold surface layer 12. (The above is the second step).

Further, as shown in FIG. 5E, a sheet wax S having the same shape as that of the target product is attached to the inner surface of the epoxy resin mold 10 to obtain a core model M3 for forming the core-side epoxy resin mold. .

Next, the following steps will be described with reference to FIG. In FIG. 6A, first, a core-side backing layer 22 prepared in advance is set on the core model M3.
Lower surface 22a of backing layer 22 and upper surface M3 of core model M3
A space is formed between the substrate and a in the shape of the desired mold surface layer. The material of the backing layer 22 is the same as that of the backing layer 12. The backing layer 22 has a cooling pipe 23 for cooling the mold surface layer that is in close contact with the backing layer 22. It has two epoxy resin injection pipes 24, 24, and one epoxy resin discharge pipe 25 in the center, and penetrates from the upper surface to the lower surface of the backing layer 22.

The mixture E obtained by mixing a metal powder such as an aluminum powder into an epoxy resin is the same as that used for preparing the epoxy resin mold on the cavity side, and the metal powder is dispersed and remains in the mixture E in the same manner. The defoaming process of the generated bubbles is performed.

Then, as shown in FIG. 6A, the backing layer 22 is placed in the oven G, heated to 35 to 60 ° C., and set on the core model M3. The inside of the oven G is again evacuated, the epoxy resin mixture E is injected from the hoppers F, F through the epoxy resin injection pipes 24, 24 of the backing layer 12, and the epoxy resin mixture is discharged from the epoxy resin mixture discharge pipe 25. Fill until E overflows. (The above is the first step).

When the filling of the epoxy resin mixture E is completed, a vacuum box (heating oven) as shown in FIG.
The epoxy resin mold is taken out of G, and cooling water W is flowed through the cooling pipe 23 to forcibly cool the epoxy resin mold to room temperature. Next, the cooled resin mold 20 is placed in an oven G as shown in FIG. 6C and left at room temperature for 12 hours to temporarily cure the mold surface layer 21. (The above is the second step).

Further, as shown in FIG. 6 (d), the sheet wax S was removed, and the mold was heated in an oven G at 50 ° C. for 6 hours, so that the mold surface layers 11, 2 on both the cavity side and the core side were removed.
1 is secondarily cured. Then, as shown in FIG. 6E, the mold surface layers 11 and 21 are tertiarily cured by further heating at 150 ° C. for 6 hours, thereby completing the epoxy resin molds 10 and 20 on the cavity side and the core side. (The third step).

In the above embodiment, when the epoxy resin mixture E is injected in the first step, the hoppers F, F
And the epoxy resin injection pipes 14 and 24 are also oven G
And the oven G is evacuated, and the hopper F,
Although the epoxy resin put in F is injected under vacuum, the following may be applied. That is, hopper F,
Put F out of oven G, pipe 1 for epoxy resin injection
4 and 24 via a valve. After evacuating the inside of the oven G with the valve closed, the valve is opened, and the epoxy resin mixture vacuum degassed in another oven is transferred from the hoppers F and F to a large scale. Inject under pressure. In this way, the injection becomes easier due to the atmospheric pressure. A sheet wax S is attached to the core model M3 that has been subjected to the primary curing (second step) of the epoxy resin mold 10 on the cavity side, and secondary curing and tertiary curing (third step) are performed in the cavity. Although the number of steps is reduced with the side and the core side set, the two may be separately performed until the tertiary curing for convenience.

As shown in FIG. 1, the epoxy resin mold 1 of the present invention manufactured as described above has the cavity-side epoxy resin mold 10 and the core-side epoxy resin mold 20 as described above. Mold surface layers 11, 21 and backing layer 12,
22 adheres well and there is no risk of cracking or delamination, and since air bubbles are removed under vacuum, there is no risk of air accumulation. Although the thickness of the mold surface layer is not particularly limited, according to this method, it is possible to cast a mold having a thickness of 15 mm or less, and if the thickness is 15 mm or less, a mold having good dimensional accuracy and excellent mechanical strength can be obtained. Therefore, the temperature of the surface of the mold surface layer can be easily adjusted, and the thickness is more preferably about 4 to 8 mm. Since the backing layer is made of metal, forced cooling of the mold surface layer that is in close contact with it is uniformly performed, and the backing layer is provided with a cooling pipe, so cooling the mold surface layer by simply supplying cold water to it it can. Therefore, the target product can be molded with high accuracy by using this resin mold.

[0049]

EXAMPLE In order to confirm the effect of the present invention, as an example, a resin mold 90 shown in FIG. 9 was experimentally manufactured. FIG. 9 (a)
FIG. 2B is a partial vertical cross-sectional view thereof, and FIG.
FIG. 3C is a cross-sectional view taken along the line XX. Resin mold 90
Is composed of a mold surface layer 91 and a backing layer 92. The mold surface layer 91 is provided with ridges 96 arranged in a lattice. MYX-06 manufactured by Mitsubishi Yuka Co., Ltd. was used for the epoxy resin of the mold surface layer 91, and zinc was used for the backing layer 92. The vertical interval s ₁ and the horizontal interval s ₂ of the ridges 96 of the backing layer are both 20 mm, and the height t ₁ is 4 m.
m. The mold surface layer 91 had a width W of 35 mm, a thickness t of 15 mm, and a length of 750 mm.

Further, as Comparative Example A, a prototype in which the convex portion 96 of the above embodiment was not provided was manufactured. The casting method of the mold surface layer 91 was a method of casting under vacuum as in the example. Further, Comparative Example B was formed by injecting the mold surface layer under normal pressure, with the structure having the same convex portions as in the example. As a result of observation after trial production, delamination and cracking were observed in Comparative Example A, and air pockets were observed in a part of the base of the convex portion 96 in Comparative Example B. Neither cracks nor air pockets were observed. Comparative example A
As in Comparative Example C, a resin mold having no convex stripes and a short length of 35 mm was produced as Comparative Example C. No delamination or cracking was observed. Therefore, it is considered that delamination or cracking would occur if there is no stretch prevention portion.

A cavity-side resin mold corresponding to the core-side resin mold 90 was manufactured by the same manufacturing method as that for the core side, and a prototype was molded using this pair of resin molds. Good molding was possible in a 24-second cycle. In the case of using the resin mold of Comparative Example A, the number of cycles was 50 to 60. Therefore, in the case of the example, it was found that the provision of the ridge 96 significantly improved the cooling efficiency.

[0052]

As described above, according to the first aspect of the present invention, a stretch preventing portion for preventing the mold surface layer from stretching with respect to the backing layer is provided on the mold surface layer side of the backing layer. Thereby, expansion and contraction of the mold surface layer with respect to the backing layer is prevented, and even in the case of a large resin mold, delamination and cracking of the mold surface layer are prevented by the expansion and contraction preventing portion. Further, by injecting a mixture of epoxy resin and metal powder into the backing layer under vacuum as a mold surface layer to form a mold surface layer, there is no risk of bubbles being trapped at the time of injection and no air accumulation. Therefore, there is an effect that delamination and cracking of the mold surface layer can be more reliably prevented.

According to a second aspect of the present invention, in addition to the effects of the first aspect, by providing an intersecting strip disposed on the entire mold surface layer side of the backing layer, expansion and contraction in any direction is possible. Is also prevented, and the concentration of internal stress is also prevented, so that an effect is obtained that delamination and cracking are more reliably prevented.

According to the third aspect of the present invention, in addition to the effect of the second aspect of the present invention, since the ridge portion is formed as a ridge, an inverted groove is formed in the mold for casting the backing layer. This is advantageous in that the mold can be easily manufactured.

According to the invention of claim 4, in addition to the effect of any of the inventions of claims 1 to 3, in the mold surface layer casting step, the mixture is heated in the first step to form an epoxy resin. The viscosity is reduced, the fluidity of the resin is improved, the thickness of the mold surface layer can be reduced to 15 mm or less, and the mixture is kept at the heating temperature because it is forcibly cooled in the second step. The time is short, heat curing is prevented from progressing rapidly with residual heat, and since it is completely cured by heating in the third step, dimensional accuracy is good, mechanical strength is excellent, and temperature control of the mold surface is easy. It has the effect of becoming.

According to the fifth aspect of the present invention, since the backing layer is provided on the mold surface layer side with an expansion / contraction preventing portion for preventing expansion / contraction of the mold surface layer with respect to the backing layer, delamination between the backing layer and the mold surface layer can be prevented. This has the effect of preventing cracks in the mold surface layer.

According to a sixth aspect of the present invention, in addition to the effects of the fifth aspect of the present invention, by providing an intersecting strip portion provided on the entire mold surface layer side of the backing layer, the Since expansion and contraction are also prevented and concentration of internal stress is also prevented,
This has the effect that delamination and cracking are more reliably prevented.

According to the seventh aspect of the present invention, in addition to the effects of the fifth or sixth aspect of the present invention, since the strip provided on the mold surface layer side of the backing layer has a key shape which is difficult to remove, The expansion and contraction of the surface layer in the thickness direction is also prevented, and an effect is obtained that delamination and cracking of the mold surface layer from the backing layer are more reliably prevented.

[Brief description of the drawings]

FIG. 1 is a sectional view of an epoxy resin mold of the present invention.

FIG. 2 is an explanatory view of a process of manufacturing an inverted model of an epoxy resin type backing layer of the present invention.

FIG. 3 is an explanatory diagram of a process of manufacturing a mold of a backing layer having an epoxy resin type convex stripe according to the present invention.

FIG. 4 is an explanatory view of a process of casting an epoxy resin type backing layer of the present invention.

FIG. 5 is an explanatory view of a casting process of an epoxy resin mold surface layer of the present invention.

FIG. 6 is an explanatory view of a casting process of an epoxy resin mold surface layer of the present invention.

FIG. 7 is a conceptual explanatory view of an operation of an expansion / contraction preventing portion provided in a backing layer.

FIG. 8 is an explanatory view of a process for producing a mold of a backing layer having concave portions of the epoxy resin type according to the present invention.

FIG. 9 is a sectional view of an embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Mold for epoxy resin molding 10, 80 Epoxy resin mold on cavity side 11, 81 Same as above Mold surface layer 12, 82 Same as above Backing layer 13, 83 Same as above Cooling pipe 14, 84 Same as above Epoxy resin injection pipe 15, 85 Same as above epoxy resin Discharge pipes 16, 86 Convex ridges, which are expansion / contraction portions provided on the mold surface layer side of the backing layer 17 Convex ridges, which are expansion / contraction portions provided on the mold surface layer side of the backing layer 18 On the mold surface layer side of the backing layer Continuous irregularities which are provided as expansion / contraction prevention portions 20 Epoxy resin mold on core side 21 Same as above Surface layer 22 Same as above Backing layer 23 Same as above Cooling pipe 24 Same as above Epoxy resin injection pipe 25 Same as above Epoxy resin discharge pipe 26 Backing layer mold surface Protrusions which are stretching prevention portions provided on the layer side 27 Protrusions which are stretching prevention portions provided on the mold surface layer side of the backing layer 28 Mold surface layers of the backing layer Continuous unevenness that is a stretch prevention part provided on the side

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[Procedure amendment]

[Submission date] July 8, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0049

[Correction method] Change

[Correction contents]

[0049]

EXAMPLE In order to confirm the effect of the present invention, as an example, a resin mold 90 shown in FIG. 9 was experimentally manufactured. FIG. 9 (a)
FIG. 2B is a partial vertical cross-sectional view thereof, and FIG.
FIG. 3C is a cross-sectional view taken along the line XX. Resin mold 90
Is composed of a mold surface layer 91 and a backing layer 92. The mold surface layer 91 is provided with ridges 96 arranged in a lattice. MYX-06 manufactured by Mitsubishi Yuka Co., Ltd. was used for the epoxy resin of the mold surface layer 91, and zinc was used for the backing layer 92. The vertical interval s ₁ and the horizontal interval s ₂ of the ridges 96 of the backing layer are both 20 mm, and the height t ₁ is 4 m.
m. -Type surface layer 91, the width W is 35 0 mm, the thickness t
Was 15 mm and the length was 750 mm.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0050

[Correction method] Change

[Correction contents]

[0050] As a comparative example A, was a prototype which is not provided with the convex 96 of the above embodiment. The casting method of the mold surface layer 91 was a method of casting under vacuum as in the example. Further, Comparative Example B, the structure is assumed to have the same protruding strip as in Example was molded by injecting mold surface layer under normal pressure. Observation after trial, the comparative example A, are delamination or cracks were observed, also in Comparative Example B but an air pocket in a part of the base of the ridges 96 is observed, the embodiment delamination, Neither cracks nor air pockets were observed. Comparative example A
Similar, but without the ridge, where the length was manufactured a short resin type of 35 0 mm As comparative examples C, since delamination or cracking was observed, when the 35 0 mm or more long length In addition, since the entire expansion and contraction becomes large, it is considered that delamination and cracking occur without the expansion and contraction preventing portion.

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Claims (7)

[Claims] 1. A method of manufacturing an epoxy resin mold, wherein a mold surface layer is formed of a mixture of an epoxy resin and a metal powder, and a backing layer in close contact with the mold surface layer is formed of metal. A backing layer casting step of forming a backing layer provided on the surface layer side with an expansion / contraction preventing portion for preventing expansion / contraction of the mold surface layer with respect to the backing layer; and injecting the mixture into the backing layer under vacuum to form a mold. A method for producing an epoxy resin mold, comprising: a mold surface layer casting step of forming a surface layer. 2. The epoxy resin composition according to claim 1, wherein the expansion / contraction portion formed in the backing layer casting step is an intersecting strip portion provided on the entire mold surface layer side of the backing layer. Manufacturing method of resin mold. 3. The method according to claim 2, wherein the strip is a convex strip. 4. The mold surface layer casting step according to claim 1, wherein the mixture is heated, and the heated mixture is injected into the backing layer under vacuum. A first step of forming a surface layer, a second step of forcibly cooling the mold surface layer, and then curing the mold surface layer at room temperature, and a third step of heating and curing the mold surface layer. A method for producing an epoxy resin mold, comprising: 5. A mold surface layer formed of a mixture of an epoxy resin and metal powder, and a metal backing layer in close contact with the mold surface layer, wherein the backing layer is provided on the mold surface layer side of the backing layer. An epoxy resin mold characterized by having an expansion / contraction preventing portion for preventing expansion / contraction of the mold surface layer with respect to the mold. 6. The epoxy resin according to claim 5, wherein the expansion / contraction preventing portion formed in the backing layer casting step is an intersecting strip portion provided on the entire mold surface layer side of the backing layer. Manufacturing method of resin mold. 7. The method of manufacturing an epoxy resin mold according to claim 5, wherein a cross-section of the ridge portion has a hook shape which is difficult to remove.