JP3584548B2 - Molding apparatus for molding and method for producing molded article - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to a molded article, and particularly to a molding apparatus for obtaining a so- called matte molded article (low gloss molded article) having a low degree of gloss on the surface of a resin molded article, and a molding die apparatus for the molded article. It relates to a manufacturing method .
[0002]
[Prior art]
Conventionally, as a technique for obtaining such a low gloss molded product, a blasting method called grid blast or sand blast can be given. In this blasting method, the molding surface of the mold is irradiated with metal coarse particles, sand, or an abrasive. Then, the molding surface is shaved by the kinetic energy of the particles, and the surface is roughened. As described above, by using a mold having a roughened molding surface, a molded article having a so-called matte surface is transferred and molded.
[0003]
[Problems to be solved by the invention]
However, the above-described conventional technology has the following problems. That is, in the above technique, even when sand having the smallest particle size is used as the particles to be irradiated, the particle size is several μm. For this reason, as shown in FIG. 5, there is a limit in roughening the molding surface 52 of the mold 51, and it is difficult to obtain a product with a lower gloss than that.
[0004]
Further, as shown in the figure, since the molding surface 52 of the roughened mold 51 is exposed, depending on the material constituting the mold 51, rust or corrosion may occur immediately. There was a risk. Therefore, when the mold apparatus is not used, it is necessary to apply a rust inhibitor to the molding surface 52 in advance.
[0005]
Further, the roughened portion of the molding surface 52 was very brittle, and was easily worn by contact with a resin or the like. Therefore, while the molding is repeated, fine irregularities on the molding surface 52 are shaved and disappear, and there is a possibility that a low gloss product expected at the beginning may not be obtained.
[0006]
The present invention has been made in order to solve the above problems, the purpose of which is to provide a molded article with a reduced surface gloss, the molded article with a reduced gloss easily, Another object of the present invention is to provide a method for producing a molded article that can be stably obtained over a long period of time. Further, another object of the present invention is to provide a molding die apparatus capable of obtaining such a low-gross molded article and improving corrosion resistance and durability.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 includes at least two split molds made of metal , and at least one of the split molds is a carbon steel mixed with chromium and molybdenum as an SCM material. A molding die apparatus for molding a molded product with a molding surface formed in the split mold, wherein at least one of blasting and graining is performed on at least a part of the molding surface. Hydrogen gas is introduced into the surface, and fine irregularities are formed by an ion nitriding process in which a flow ratio of hydrogen gas 1 to hydrogen gas 1 is more than 0 and less than 0.2. In addition, the gist is that a nitride layer is formed on the surface layer .
[0008]
According to a second aspect of the present invention, a step of filling a plasticized resin material into a cavity formed by the molding surface of the molding die apparatus of the first aspect, The gist of the present invention is a method for producing a molded article having a matte surface, which comprises a step of removing the solidified product from the molding die apparatus .
[0014]
It is needless to say that nitrogen gas must be used in the above ion nitriding treatment.
The SCM-based material is a carbon steel mixed with chromium and molybdenum, and is a steel material specified in JIS G4105 and JIS G4103.
[0015]
[Action]
According to the above-mentioned invention, in particular, the invention according to claim 1 , at least a part of the molding surface of the split mold made of the SCM-based material among the split molds constituting the molding die apparatus is provided with carbon monoxide. Gas is introduced to perform ion nitriding. For this reason, predetermined ions collide with the molding surface, the surface is roughened by an etching action, and fine irregularities are formed. At the same time, with the collision of ions, the surface temperature of the mold increases, and nitrogen atoms diffuse into the surface of the divided mold. Furthermore, a nitrided layer is formed on the surface of the molding surface due to the chemical reaction accompanying the ion collision. Therefore, the combination of these actions makes the surface roughened very fine. In particular, in the present invention, since the carbon monoxide gas is introduced, a nitride layer having a fine uneven surface on the surface of the molding surface is more easily formed.
[0016]
Further, since a nitride layer is formed on the surface of the molding surface by the above-described chemical reaction, the surface is hardly oxidized, and the hardness of the surface layer of the split mold is increased.
[0017]
Further, at a predetermined point formed form surface, at least one of blast processing and texturing is performed. Then, ion nitriding is performed on the processed surface. For this reason, the formed surface which has been relatively roughened once by blasting or graining is subjected to a finer roughening treatment by the above-mentioned ion nitriding treatment.
[0018]
Further, the ion-nitriding treatment, further, together with hydrogen gas is introduced, as the carbon monoxide gas, the flow ratio of carbon monoxide gas to hydrogen gas 1 is greater than 0, and than 0.2 It will be introduced in a small amount. For this reason, the above-mentioned operation is further ensured.
[0019]
On the other hand, since the mold exhibit the effect of the invention described above Symbol claim 1 device is used, the molded article will have a transferred surface shape on the molding surface. Therefore, the surface of the molded article has low gloss and low gloss.
[0020]
Also be achieved is dramatically improved texture to further.
[0021]
Further, formed molded article is made of a resin material, a resin molded article obtained in this way is superior to the antiglare property.
[0022]
Furthermore, according to the second aspect of the present invention, the cavity formed by the molding surface of the molding die apparatus according to the first aspect is filled with a plasticized resin material, and the resin material is filled. Is solidified and taken out of the molding die apparatus to obtain a resin molded product. Therefore, it is possible to easily obtain a molded product having the above-described operation simply by using such a mold device.
[0023]
【Example】
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, a molding die apparatus 1 according to the present embodiment includes a movable die 2 constituting a split die and a fixed die (not shown). The movable mold 2 and the fixed mold are made of an SCM-based material (for example, grade PX5 manufactured by Daido Steel Co., Ltd., surface grain finish). A molding surface 3 for molding a predetermined resin product is formed on a part of the movable mold 2 and a part of the fixed mold. The molding surface 3 constitutes a cavity for molding a predetermined resin product together with the molding surface of the fixed die. The molding surface 3 is subjected to graining in advance, and is further subjected to ion nitriding from above.
[0024]
In such an ion nitriding process, an ion nitriding apparatus 4 as shown in FIG. 2 is used. That is, the ion nitriding apparatus 4 has a furnace wall 5 and a pedestal-shaped DC electrode 6 is installed in the furnace wall 5. Further, a pressure reducing pipe 7 is provided on the furnace wall 5, and the pipe 7 is connected to a vacuum pump (not shown). Further, a source gas obtained by mixing at least a nitrogen gas and a hydrogen gas is supplied into the furnace wall 5.
[0025]
Next, an example of an ion nitriding method of the molding surface 3 of the movable mold 2 using the above-described ion nitriding apparatus 4 will be described.
First, as shown in FIG. 3, a movable mold 2 in which a molding surface 3 is pre-textured is prepared, and ultrasonic cleaning with trichloroethane is performed as a pretreatment for about 30 minutes. This washing also serves as degreasing. Note that acetone, isopropyl alcohol, or the like may be used for such cleaning and degreasing. Thereafter, the movable mold 2 is dried at room temperature.
[0026]
Next, the movable mold 2 that has undergone the pretreatment step is placed and fixed on the DC electrode 6. Then, the pressure inside the furnace wall 5 is reduced to a predetermined pressure (for example, 26.6 Pa) by a vacuum pump, and then the raw material gas [gas pressure: 260 to 400 Pa, flow rate: 5 L / min, gas flow rate ratio: N ₂ : H ₂ : N ₂ (80%) + CO (20%) = 1.2: 2: 1 (N ₂ : H ₂ : CO = 1: 1: 0.1)] is introduced into the furnace wall 5.
[0027]
Further, using the DC electrode 6 as an anode and the furnace wall 5 as a cathode, plasma is generated with a DC current of 8 A (voltage 500 V), and the movable mold 2 is heated to 575 ° C. in about 30 minutes. Thereafter, the temperature of the movable mold 2 is kept at the fixed value, and ion nitriding is performed for a predetermined time (for example, 3 hours) [current about 4 A (voltage about 600 V) at this time]. After a lapse of a predetermined time, only the discharge is stopped, and after cooling for a certain time (for example, 1.5 hours), the movable mold 2 is taken out of the furnace wall 5.
[0028]
In the movable mold 2 thus obtained, since the molding surface 3 is subjected to the ion nitriding treatment, predetermined ions (nitrogen ions, hydrogen ions, etc.) collide with the molding surface 3 and its kinetic energy The surface is roughened by the etching action of, and fine irregularities are formed. At the same time, the surface temperature of the movable mold 2 rises due to the collision of ions, and nitrogen atoms diffuse into the divided surface layer. Further, a nitrided layer is formed on the surface of the molding surface 3 by a chemical reaction accompanying the ion collision. Therefore, the combination of these actions makes the surface roughened very fine. In particular, in this embodiment, since the carbon monoxide gas is introduced, a nitride layer having a fine uneven surface on the surface of the molding surface 3 is more easily formed.
[0029]
In order to confirm the above-mentioned effects, the split type test piece of the mold apparatus subjected to only the conventional blast treatment (Comparative Example 1) and the split type test piece of the mold apparatus of the present embodiment (Example 1) And a divided test piece of a mold apparatus in which the gas flow ratio at the time of the ion nitriding treatment was changed with respect to the conditions of the embodiment [molded article obtained with no carbon monoxide / N ₂ : H ₂ = 1: 1 ( Comparative Example 2)], the gloss was measured when viewed from an angle of 60 °. The gloss was evaluated using a digital gonio-gloss meter UGV-5K and SM Color Computer SM-5 in accordance with JIS Z8741.
[0030]
The gloss value of the test piece of Example 1 was “0.3”. On the other hand, the gloss value of the test piece of Comparative Example 1 was “1.5”, and the gloss value of the test piece of Comparative Example 2 was “1.0”. As can be seen from the above results, the molding apparatus of the present embodiment can have a molding surface with a low glossiness, that is, a so-called low gloss. In addition, in the split type of the SCM material according to the present embodiment, it can be seen that the gross reduction can be drastically achieved by introducing carbon monoxide when performing the ion nitriding treatment.
[0031]
Referring to the further operation and effect of this embodiment, the surface temperature of the movable mold 2 is increased by the above-described chemical reaction, and nitrogen atoms are diffused into the surface layer of the movable mold 2. Therefore, the hardness of the surface layer of the movable mold 2 is increased. As a result, it is possible to suppress the abrasion of fine irregularities on the molding surface 3 and to improve the durability of the mold apparatus 1.
[0032]
Further, a nitrided layer (Fe ₂ N, Fe ₃ N, Fe ₄ N) is formed on the surface of the molding surface 3 by a chemical reaction accompanying the collision of ions. Therefore, the surface is hardly oxidized by the presence of such a nitrided layer. As a result, there is no need to apply a rust preventive or the like to the molding surface, so that productivity can be improved and costs can be reduced accordingly.
[0033]
Next, the effect of injection molding a resin molded product using the movable mold 2 or the like obtained as described above will be described.
In the present embodiment, as shown in FIG. 4, for example, the outer piece 12 of the instrument panel 11 is manufactured from polypropylene using a known injection molding method as a molded product. Since the outer piece 12 is generally located near a windshield (not shown), the outer piece 12 is an interior component that is highly demanded to prevent reflection on the windshield.
[0034]
According to the present embodiment, since the molding surface 3 of the movable mold 2 is subjected to the ion nitriding treatment, the roughened state of the molding surface 3 becomes very fine as described above. For this reason, the resin molded product (outer piece 12) transferred and molded by the molding surface 3 has a so-called matte surface, and the surface can have a low gloss.
[0035]
In addition, in the present embodiment, in particular, since the movable mold 2 which has been subjected to graining in advance is used, the molding surface 3 which has been roughly roughened once by graining is subjected to the ion nitriding treatment. Further finer roughening processing is performed. For this reason, the texture of the obtained molded article can be dramatically improved. That is, not only is a low-gloss molded article (outer piece 12) obtained, but also the surface has low brightness.
[0036]
From these facts, according to the molded article of the present embodiment, excellent anti-glare properties are exhibited. In particular, when the molded article is used as an interior part of an automobile (for example, the outer piece 12 of the instrument panel 11), a windshield or the like is used. This has the effect of eliminating the problem caused by reflection in the image.
[0037]
The present invention is not limited to the above embodiment, and may be configured as follows, for example.
(1) In the above-described embodiment, the present invention has been embodied in the case of obtaining a resin molded product, in particular, the outer piece 12 of the instrument panel 11, but may be embodied in various resin molded products including other interior products. Further, the present invention may be embodied in the case of molding another molded product such as a metal.
[0038]
(2) In the above embodiment, the case where the ion nitriding process is performed on the molding surface 3 of the movable die 2 is embodied. However, the embodiment is realized when the ion nitriding process is performed on the molding surface of the fixed die and other split dies. You can also. Further, it is not necessary that the entire molding surface 3 be subjected to the ion nitriding treatment, and at least a part thereof may be subjected to the treatment.
[0039]
(3) The treatment conditions for the ion nitriding treatment are not limited to the numerical values and the like in the above embodiment. For example, the flow rate ratio of the nitrogen gas may be appropriately changed.
[0040]
(4) In the above embodiment, the molding surface 3 which has been subjected to graining in advance is subjected to ion nitriding, but the graining may be omitted. Also, blasting may be performed instead of graining. Even when such processing is performed, it is possible to improve the texture equivalent to the graining. Further, the processing of the present invention may be performed after the graining and the blast processing are used together.
[0041]
The technical ideas which are not described in each claim of the claims and can be grasped from the above embodiment are described below together with their effects.
(A) The molding die apparatus and the method of manufacturing a molded product according to claim 1 or 2 , wherein the molded product constitutes a part of an instrument panel for a vehicle. . With such a configuration, an excellent antiglare property can be obtained, and in particular, an effect that a problem due to reflection on a windshield or the like can be eliminated can be achieved.
[0042]
【The invention's effect】
As described above in detail , according to the molding die apparatus of the present invention, it is possible to obtain the above-described molded article having a reduced gloss, and at the same time, it has an excellent effect of improving corrosion resistance and durability. Play. Further , according to the method for producing a molded article of the present invention, it is possible to obtain a molded article with a reduced surface gloss, and the molded article with a reduced gloss can be easily obtained over a long period of time. It has an excellent effect of being obtained stably.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing a molding surface of a movable mold according to one embodiment.
FIG. 2 is a schematic view showing an ion nitriding apparatus.
FIG. 3 is a cross-sectional view schematically showing a movable die subjected to graining.
FIG. 4 is a perspective view showing an instrument panel and the like.
FIG. 5 is a cross-sectional view schematically showing a mold according to the related art.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Mold apparatus, 2 ... Movable mold as a split mold, 3 ... Molding surface, 12 ... Outer piece as a molded product.

Claims (2)

At least two split molds (2) made of metal are provided, and at least one of the split molds (2) is made of carbon steel mixed with chromium and molybdenum as an SCM material and formed in the split mold (2). A molding die apparatus for molding a molded article from the molded surface (3),
Hydrogen gas is introduced into a surface on which at least one of blast processing and grain processing has been performed on at least a part of the molding surface (3), and a flow ratio to hydrogen gas 1 is more than 0, and A molding die apparatus, wherein fine irregularities are formed by ion nitriding treatment by introducing less than 0.2 carbon monoxide gas, and a nitride layer is formed on a surface layer. Filling a plasticized resin material into a cavity formed by the molding surface (3) of the molding die apparatus (1) according to claim 1;
Removing the solidified resin material from the molding die apparatus. A method for manufacturing a molded article, characterized by having a matte surface.

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