JP2003334819A - Method for manufacturing mold and mold - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain excellent surface transfer properties and a good dimensional precision while a manufacturing period is enough shortened. <P>SOLUTION: A master model 6 having a form equivalent to that of a molding (sheet) is manufactured. Electrocasting is applied to the surface of the master model 6, and an electrodeposited nickel layer 3, for example, 0.1 mm in thickness is formed on the surface of the master model 6 (a) and (b). Plasma flame coating is applied to the surface (outer surface) of the nickel layer 3, and an undercoat layer 5 of a Ni-Cr alloy, for example, 100 μm in thickness is formed (c) and (d). Next, plasma flame coating is applied to the surface (outer surface) of the undercoat layer 5, and a flame-coated metal layer 4 of a Ni alloy, for example, 3 mm in thickness is formed (d) and (e). After that, the three metal layers are demolded from the master model 6 to obtain a mold 1 (f) and (g). <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold and a method for manufacturing a mold used for injection molding, powder slush molding, rotational molding, RIM molding, RTM molding and the like.

[0002]

In car interior parts such as automobile instrument panels, door trims, grab doors, console boxes, etc., there is a case in which the outer skin is made of a resin molded sheet, The surface is provided with a fine uneven pattern such as a so-called leather grain pattern. In this case, generally, for the molding of the sheet, powder slush molding using a powder material such as vinyl chloride or urethane is adopted,
In manufacturing such a die for powder slush molding, electroforming which is excellent in surface transferability and dimensional accuracy is used.

However, the method of manufacturing a mold by electroforming has the advantages of excellent surface pattern transferability and dimensional accuracy, but has the disadvantage of requiring a longer period of time to manufacture the mold. It takes about 40 days to complete the above process alone. On the other hand, in recent years, the development period of new products has been shortened, and even in the production of molds for various moldings, there is a demand for speeding up.

Therefore, the present inventors have focused on a thermal spraying method of a metal material as an alternative method to electroforming, and have a high heat resistance by producing a thermal spraying object, that is, a thermal spraying model by sintering a ceramic-metal composite powder. We have tried to use the thermal spraying method in the manufacture of the mold by devising such things as making things. By using this thermal spraying method, it is possible to significantly shorten the manufacturing period of the mold. However, in this method, the sprayed metal layer is formed relatively thick in order to guarantee the strength of the mold, but the stress (contraction) generated during solidification of the sprayed metal layer causes distortion, etc. However, the dimensional accuracy is inferior to that in the case of using, and since it is an aggregate of fine metal powders, the surface transferability is inferior to that in electroforming.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a mold capable of obtaining excellent surface transferability and dimensional accuracy while making it possible to shorten the manufacturing period sufficiently. A manufacturing method and a mold are provided.

[0006]

In order to achieve the above object, the method of manufacturing a mold of the present invention is designed such that Ni, Ni-based alloy, Cu, An electroforming step of forming an electrodeposited metal layer having a thickness of about 0.05 to 2.0 mm by electroforming with any of Cu alloys, and F on the surface side of the electrodeposited metal layer.
e, Fe alloy, Ni, Ni alloy, Co, Co alloy, C
A thermal spraying step of forming a thermal sprayed metal layer having a thickness of about 3 to 8 mm by plasma spraying with any one of u, Cu alloy, Al and Al alloy, and separating the metal layer formed on the surface of the master model from the master model. The present invention is characterized in that it includes a releasing step of obtaining a mold by molding (the invention of claim 1).

According to this, the inner surface (product surface) of the mold is
Since it is composed of an electrodeposited metal layer formed by electroforming, it is possible to transfer minute irregularities on the surface of the master model with high accuracy, and it is also possible to cope with complicated shapes. Further, the thermal sprayed metal layer formed on the outer surface side of the electrodeposited metal layer is, as it were, built up, so that the strength of the mold is secured. At this time, since the sprayed metal layer formed by plasma spraying is formed on the metal layer having high rigidity, the size and shape are maintained. And since the electrodeposited metal layer can be thin, the period required for the electroforming process is shorter than the case of forming the whole by electroforming, and the spraying process itself can be performed in a short period, so that The manufacturing period of the mold can be shortened sufficiently.

In this case, the thickness of the electrodeposited metal layer is
The thickness can be set in the range of about 0.05 to 2.0 mm according to the application, and the thickness of the sprayed metal layer can be set in the range of about 3 to 8 mm according to the application. it can. Ni is generally used as the material of the metal used for electroforming, but Ni alloy, Cu, Cu alloy or the like can also be adopted according to the characteristics required for the mold. The material of the metal used for thermal spraying is F if it can be plasma sprayed and can be thickened.
e, Fe alloy, Ni, Ni alloy, Co, Co alloy, C
u, Cu alloy, Al, Al alloy, etc. can be selected according to the application.

Further, at this time, it is possible to form the thermal sprayed metal layer into a plurality of layers from different metals. Regarding the particle size of the thermal spray material, when the pressure at the time of molding is not so high, a coarse particle of about several hundred μm can be used, and when pressure resistance is required, a fine particle of several μm to several tens of μm can be used. By adopting plasma spraying among the spraying methods, it is possible to increase the adhesion of fine metal powder and to make the sprayed metal layer more compact.

At this time, before performing the thermal spraying step, the surface of the electrodeposited metal layer formed by the electroforming step is subjected to plasma spraying with a Ni-Cr alloy or a Ni-Al alloy to obtain a thickness number. It becomes more effective if the undercoat layer forming step of forming the undercoat layer of 10 to several hundreds of μm is performed (the invention of claim 2).

According to this, even when the film thickness of the sprayed metal layer is large, the stress generated at the time of solidification can be relieved by the undercoat layer serving as a buffer layer, and the stress can be reduced. The adhesive strength with the sprayed metal layer can be enhanced.
It also plays a role of relaxing the thermal expansion coefficients of the electrodeposited metal layer and the sprayed metal layer. In this case, as the material of the undercoat layer, a Ni-Cr alloy or a Ni-Al alloy can be adopted. Among them, the Ni-Cr alloy is strong against oxidation, and therefore corrosion at high temperature is considered. Can be adopted when required.

The mold of the present invention is an electrodeposited metal having an inner surface made of any one of Ni, Ni-based alloy, Cu, and Cu alloy, and having a concavo-convex shape opposite to that of a molded product and having a thickness of 0.05 to 2.0 mm. Fe, Fe alloy, Ni,
Ni alloy, Co, Co alloy, Cu, Cu alloy, Al, A
The present invention is characterized in that it has a sprayed metal layer having a thickness of 3 to 8 mm made of any one of the L alloys (invention of claim 3). According to this, as described above, excellent surface transferability and dimensional accuracy can be obtained while the manufacturing period can be sufficiently shortened.

In this case, if an undercoat layer made of a Ni--Cr alloy or a Ni--Al alloy having a thickness of several tens to several hundreds μm is provided between the electrodeposited metal layer and the sprayed metal layer, It is more effective (invention of claim 4), whereby the undercoat layer serves as a buffer layer to relieve the stress generated at the time of solidification of the sprayed metal layer, and also the electrocoated metal layer and the sprayed layer It also plays the role of relaxing the coefficient of thermal expansion with the metal layer.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment in which the present invention is applied to the production of a mold for powder slush molding will be described below.
A description will be given with reference to the drawings. First, the mold 1 manufactured by the manufacturing method according to the present embodiment includes a seat 2 (FIG. 3 (e)) that constitutes a skin of a vehicle interior part such as an instrument panel, a door trim, a grab door, and a console box of a vehicle. (See) is formed by the powder slush molding method. In this case, the molded product (sheet 2) is made of, for example, vinyl chloride (PVC) or urethane, and is molded to a thickness of about 1.5 mm.

As shown in FIG. 1 (g), FIG. 3 (a), etc., this mold 1 has an outer surface (surface shape) of a sheet 2 as a molded product on the inner surface (the surface facing downward in the drawing). Although it is composed of a metal layer having an inverted shape and having a substantially uniform thickness as a whole, in the present embodiment, the electrodeposited metal layer 3 made of, for example, Ni and located on the inner surface side and the outer surface side are located on the inner surface side. For example, it has a three-layer structure of a sprayed metal layer 4 made of a Ni-based alloy and an undercoat layer 5 made of, for example, a Ni-Cr-based alloy located in the middle thereof.

As will be described later in detail, the electrodeposited metal layer 3 has a thickness of 0.05-2..cm by electroforming on the surface of the master model 6 (see FIGS. 1 and 2D).
It is formed with a thickness of 0.1 mm within a range of 0 mm. The undercoat layer 5 is formed by plasma spraying on the surface (outer surface) of the electrodeposited metal layer 3 to have a thickness within the range of several tens to several hundreds of μm, for example, 100 μm.

The sprayed metal layer 4 is formed by plasma spraying on the surface (outer surface) of the undercoat layer 5 to have a thickness within the range of 3 to 8 mm, for example, 3 mm. Although not shown, the surface of the mold 1 (the electrodeposited metal layer 3) is provided with a reverse concavo-convex pattern for forming a fine concavo-convex pattern such as a so-called grain pattern on the surface of the sheet 2. There is.

Next, the manufacturing process of the mold 1 will be described with reference to FIGS. To manufacture the mold 1,
A master model (prototype) 6 having the same outer shape (surface shape) as the molded product (sheet 2) is used. First, FIG.
Shows schematically the manufacturing process of this master model 6. That is, as shown in FIG. 2A, a wooden model 7 having the same outer shape as the molded product (sheet 2) (actually, it is thinner by the thickness of the next vinyl leather 8) was manufactured, and As shown in FIG. 2 (b), vinyl leather 8 (or natural leather or the like) having a fine relief pattern such as a leather grain pattern is attached to the surface of the wooden model 7.

Next, as shown in FIG. 2 (c), an inverted model 9 is produced by inverting the wooden model 7. The inverted model 9 is manufactured by casting, for example, silicone rubber on the surface of the wooden model 7, and releasing after curing. The inverted model 9 has an uneven shape that is the reverse of the outer shape of the wooden model 7, that is, the molded product (sheet 2). In this case, however, since it is manufactured by the casting method, High transfer accuracy can be obtained even with respect to the fine uneven pattern of, and it can be applied to those having a complicated shape such as an undercut shape. Although not shown, a backup layer is formed on the back side of the inverted model 9.

Subsequently, as shown in FIG. 2D, the master model 6 is manufactured from the inverted model 9.
The master model 6 is obtained by casting an epoxy resin on the surface of the reversal model 9, further laminating reinforcing fibers and the like if necessary, and after releasing the epoxy resin, releasing the reversal model 9. It is like this. Further, after that, a treatment for imparting conductivity to the surface of the master model 6 is performed.

Now, FIG. 1 shows in sequence the manufacturing steps of the mold 1 in this embodiment. The mold 1 is manufactured by an electroforming process for forming the electrodeposited metal layer 3 on the surface of the master model 6 (FIGS. 1A and 1B), and a thermal spraying method on the surface of the electrodeposited metal layer 3. Undercoat layer forming step (FIG. 1 (c)) of forming the undercoat layer 5 by the thermal spraying step of forming the metal sprayed layer 4 on the surface of the undercoat layer 5 by a thermal spraying method (FIGS. 1 (d), (e)). )) A mold release step (FIGS. 1F and 1G) of releasing the three metal layers 3, 5, and 4 from the master model 6 is sequentially performed.

That is, in the electroforming step, as shown in FIG. 1 (a), the master model 6 and the nickel electrode 11 are placed in an electroforming tank 10 made of, for example, a nickel sulfamate bath, and the This is done by passing a direct current between them. As a result, nickel is deposited on the surface of the master model 6 and electrodeposition is performed, and when the electrodeposited metal layer 3 having a predetermined thickness (0.1 mm) is formed, the electroforming process ends, and ), The electrodeposited metal layer 3 having a predetermined thickness
The master model 6 in which is formed is taken out. At this time, since the electrodeposited metal layer 3 is thin, the time required for this electroforming process can be relatively short (for example, about one week).

In the next undercoat layer forming step, as shown in FIG.
As shown in (c), the surface (outer surface) of the electrodeposited metal layer 3
On the other hand, plasma spraying is performed by a plasma spraying device (only the nozzle 12 is shown) using a powder material of Ni-Cr alloy. Thus, as shown in FIG. 1D, the undercoat layer 5 made of a Ni—Cr alloy is formed on the outer surface of the electrodeposited metal layer 3 to have a thickness of 100 μm, for example.

Next, in the thermal spraying process, as shown in FIG. 1D, a plasma thermal spraying device (only the nozzle 13 is shown) is used for the surface (outer surface) of the undercoat layer 5 by using a Ni-based alloy powder material. ) Plasma spraying is performed. In this case, since the powder slush molding die 1 does not require much pressure during molding, the particle size of the thermal spray material may be a relatively coarse particle size of several hundreds of μm. As a result, as shown in FIG.
The thermal sprayed metal layer 4 made of a Ni-based alloy is formed on the outer surface side of, with a thickness of 3 mm, for example.

However, in the above-mentioned thermal spraying process, the thermal spraying metal layer 4 is formed to be relatively thick, so that stress (contraction) may occur during solidification of the metal. For this reason, there is a possibility that dimensional accuracy may be deteriorated due to distortion or the like. However, in this embodiment, since the sprayed metal layer 4 is formed on the metal layer having high rigidity (the electrodeposited metal layer 3 and the undercoat layer 5), the size and shape can be maintained. Moreover, by providing the undercoat layer 5, the stress generated during solidification can be relieved by the undercoat layer 5 serving as a buffer layer, and the adhesive force between the electrodeposited metal layer 3 and the sprayed metal layer 4 can be reduced. Can be increased.

Through the above steps, as shown in FIG. 1E, three metal layers of the electrodeposited metal layer 3, the undercoat layer 5 and the sprayed metal layer 4 are formed on the surface of the master model 6. . Thereafter, as shown in FIG. 1 (f), a releasing step of releasing the metal layer from the master model 6 is performed, and further surface finishing is performed, so that as shown in FIG. 1 (g). , The electrodeposited metal layer 3 made of Ni, the undercoat layer 5 made of a Ni—Cr alloy, and the thermal sprayed metal layer 4 made of a Ni alloy can be obtained.

The mold 1 thus obtained has a shape obtained by reversing the outer shape (surface shape) of the sheet 2 which is a molded product, and the inner surface (the surface of the electrodeposited metal layer 3) has An uneven pattern for forming a minute uneven pattern is formed on the surface of the sheet 2. In this case, since electroforming is used to form the electrodeposited metal layer 3 forming the inner surface of the mold 1, a fine uneven pattern on the surface of the master model 6 is transferred to the mold 1 with high transfer accuracy. Can be transcribed. Further, the thermal sprayed metal layer 4 formed on the outer surface side is, as it were, built up, so that sufficient mechanical strength of the mold 1 is secured. In this case, by adopting plasma spraying among the spraying methods, the adhesion of fine metal powder is enhanced, and the sprayed metal layer 4 is formed.
Can be densified.

Since the electrodeposited metal layer 3 is thin as described above, the time required for the electroforming step is relatively short, and the subsequent undercoat layer forming step and thermal spraying step are also required. As for the process, the time required for the process can be shortened by using the thermal spraying method. As a result, the manufacturing period of the mold 1 (the period required from the electroforming process to the spraying process) is, for example, about 10 days, and the manufacturing period of the mold 1 is longer than that in the case where the entire mold is manufactured by electroforming. It was possible to achieve a significant reduction (at least less than half).

FIG. 3 shows a sheet 2 using the mold 1 described above.
The powder slush molding is briefly described below. That is, first, as shown in FIG. 3A, a mold heating step of heating the mold 1 from the back surface (outer surface) side to, for example, 250 ° C. is performed. Although not shown,
In this mold heating step, a fluidized bed furnace, hot air stove, gas furnace, oil heating or the like is used. In the fluidized bed furnace, a ceramic powder heated by a heater is sprayed onto the back surface of the mold 1 to heat the mold 1, and the mold 1 can be heated in a short time.
Is a heating system that is easily worn. Therefore, mold 1
When a fluidized bed furnace is used as the heating method of (1), a material having excellent wear resistance may be used for the sprayed metal layer 4 on the back surface (outer surface) of the mold 1.

Next, as shown in FIG. 3B, a powdery molding material 14 such as vinyl chloride or urethane is put into the surface (inner surface) of the heated mold 1. As a result, the molding material 14 located on the surface of the mold 1 becomes
It is heated by its accumulated heat capacity, melts and adheres to the surface of the mold 1 (shown as a molten resin 14a in the figure). In this case, since the electrodeposited metal layer 3 on the inner surface of the die 1 is made of Ni, it has excellent corrosion resistance against the molding material 14 such as vinyl chloride.

Next, as shown in FIG. 3 (c), the excess molding material 14 is removed (discharged), so that the molten resin 14a is adhered to the surface of the mold 1 with a predetermined thickness. Subsequently, as shown in FIG. 3D, a cooling step of immersing the back surface side of the mold 1 in the cooling water 15 at 60 ° C., for example, is performed, whereby the molten resin 14 on the surface of the mold 1 is subjected.
The sheet a, which is a molded product, is cooled and hardened by a. In this case, the heat cycle of heating and cooling is repeated in the mold 1, but the undercoat layer 5 plays a role of relaxing the thermal expansion coefficient of the electrodeposited metal layer 3 and the sprayed metal layer 4. , The thermal strength can be increased.

Thereafter, as shown in FIG. 3 (e), the mold 1
The step of releasing the sheet 2 from the surface of the sheet is executed, and the molding of the sheet 2 is completed. This sheet 2 is a mold 1
The outer shape (surface shape) is the reverse of the surface shape, and a fine uneven pattern such as a so-called skin grain pattern is formed on the surface. In this case, the fine uneven pattern on the surface of the mold 1 is transferred to the surface of the sheet 2 with high transfer accuracy.

As described above, according to this embodiment, the mold 1 is made to compensate for the defects of the conventional electroforming method and thermal spraying method.
Since the electroforming method and the thermal spraying method are combined to be manufactured, it is possible to sufficiently shorten the manufacturing period of the mold 1 and obtain excellent surface transferability and dimensional accuracy. It has an excellent effect. In particular, in this embodiment, since the undercoat layer 5 is provided between the electrodeposited metal layer 3 and the sprayed metal layer 4, the undercoat layer 5 absorbs the stress generated during solidification of the sprayed metal layer 4. Therefore, there is an advantage that the coefficient of thermal expansion of the electrodeposited metal layer 3 and the thermal sprayed metal layer 4 can be relaxed.

In the above-mentioned embodiment, Ni is generally used as the material of the electrodeposited metal layer 3, but Ni-based alloy can also be used. Specifically, when corrosion resistance is required, a Ni—Co based alloy can be adopted, and when abrasion resistance is required, a Ni—W based alloy or Ni (composite electroformed) in which SiC powder is dispersed can be used. ) Can be adopted and it is desired to suppress the thermal expansion as much as possible, a Ni-Fe alloy (Ni 45%, F
e55%) can be adopted. C on the electrodeposited metal layer
It is also possible to employ u or a CU alloy, and in short, it is possible to select a material for electroforming according to the application of the mold (required characteristics).

Similarly, regarding the material of the sprayed metal layer 4,
Fe, Fe alloy, Ni, Ni alloy, Co, Co alloy, C
u, Cu alloy, Al, and Al alloy can be selected according to the intended use. The undercoat layer 5 may also be made of a Ni-Al alloy. The undercoat layer 5 may be provided if necessary. Also,
The thickness dimension of each layer can also be set according to the required characteristics and the like. Regarding the particle size of the thermal spray material, for example, when pressure resistance is required, a fine particle of about several μm to several tens of μm can be adopted.

Furthermore, it is possible to form the sprayed metal layer 4 in two or more layers from different metals. To give a specific example, if you want to increase the thermal conductivity of the mold, Cu
It is possible to spray a system alloy of about several hundreds of μm to several mm and, after piping and fixing a hot tube along the layer, spray a metal material having poor heat conduction and high strength.

In addition, although the present invention is applied to the mold for powder slush molding in the above embodiment, it is possible to use an injection molding mold, a rotary molding mold, a RIM molding mold, an RTM molding mold,
The present invention can be applied to various molds (various molded products) such as press molds, and various modifications can be made to the manufacturing method and material of the master model.
The invention can be carried out by appropriately changing it within the scope of the invention.

[0038]

As is apparent from the above description, according to the mold manufacturing method and mold of the present invention, electroforming is performed in order to make up for the defects of the conventional electroforming method and thermal spraying method. Since the mold is manufactured by combining the thermal spraying method and the thermal spraying method, the excellent effect that excellent surface transferability and dimensional accuracy can be obtained while making it possible to shorten the manufacturing period sufficiently It plays.

[Brief description of drawings]

FIG. 1 is a view showing an embodiment of the present invention and showing a manufacturing process of a mold in order.

FIG. 2 is a diagram sequentially showing a manufacturing process of a master model.

FIG. 3 is a diagram showing a procedure of powder slush molding.

[Explanation of symbols]

In the drawings, 1 is a mold, 2 is a sheet (molded product), 3 is an electrodeposited metal layer, 4 is a sprayed metal layer, 5 is an undercoat layer, and 6 is a master model.

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Claims (4)

[Claims] 1. A surface of a master model having an outer shape equivalent to that of a molded product is electroformed with one of Ni, a Ni-based alloy, Cu, and a Cu alloy to have a thickness of 0.05 to
An electroforming step of forming an electrodeposited metal layer of about 2.0 mm, and Fe, Fe alloy, Ni, N on the surface side of the electrodeposited metal layer.
i alloy, Co, Co alloy, Cu, Cu alloy, Al, Al
By plasma spraying with any of the alloys, the thickness of 3 ~
A method of manufacturing a mold, comprising a thermal spraying step of forming a thermal sprayed metal layer of about 8 mm, and a mold releasing step of releasing the metal layer formed on the surface of the master model from the master model to obtain a mold. . 2. After the electroforming step, a Ni--Cr alloy or Ni--Al alloy is applied to the surface of the electrodeposited metal layer.
Thickness of tens to hundreds of μ due to plasma spraying with a system alloy
The method for manufacturing a mold according to claim 1, wherein an undercoat layer forming step of forming an undercoat layer of about m is performed, and then the thermal spraying step is performed. 3. Ni, Ni-based alloy, Cu, Cu on the inner surface
It has an electrodeposited metal layer made of any of the alloys and having an uneven shape reverse to that of the molded product and having a thickness of about 0.05 to 2.0 mm, and Fe, Fe alloy, Ni, Ni alloy, on the outer surface side.
A metal mold having a sprayed metal layer made of any one of Co, Co alloy, Cu, Cu alloy, Al, and Al alloy and having a thickness of about 3 to 8 mm. 4. Between the electrodeposited metal layer and the sprayed metal layer,
The mold according to claim 3, further comprising an undercoat layer made of a Ni-Cr alloy or a Ni-Al alloy and having a thickness of several tens to several hundreds of μm.