JPH11320627A - Production of mold for molding textured product and mold for molding textured product produced by method of production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a mold for molding a textured product which has high surface gloss, high grade feeling, and good scratch resistance and in which a defective appearance such as welds, nonuniformity, sink, flow marks, and others, which are generated in the product, can be made not to stand out and a method for producing the mold. SOLUTION: A texture pattern surface which is etched so that the distance between the recessed part 3a and protruded part 3b of the texture pattern formed on the surface of a mold 1 is 0.3-0.5 mm and the step difference between the recessed part 3a and the protruded part 3b is 20-40 μm is subjected to primary blast treatment with the use of a bead-shaped blast projecting material T of 100-200 mesh particle size by 0.2-0.4 MPa compressed air pressure. Moreover, the texture pattern surface after the primary blast treatment is subjected to secondary blast treatment in which compressed air pressure is equal to or exceeding that in the primary blast treatment and 0.2 MPa or below, and the blast projecting material 7 is in the same conditions with those in the primary blast treatment. In this way, the mold 1 in which only the smooth traces of the blast projecting material are left on the textured uneven surface is finished.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold for embossing a surface of a product to be injection-molded, and a method of manufacturing the mold.

[0002]

2. Description of the Related Art The main purpose of graining is to impart a subtle shadow or a moderate gloss or feel to the surface of the product by the graining, thereby giving the product a sense of quality. However, in addition to grain, weld, flow mark, which occurs on the product surface unique to plastic injection molding,
It also has a practical meaning, such as making appearance defects such as unevenness less noticeable, and preventing or making less noticeable the damage on the product surface.

[0003] However, there are few examples in which the specifications such as the uneven pitch and depth of the grain and the smoothness of the uneven surface finish are quantitatively confirmed. In addition, the correlation between grain gloss and luxury, the effect of making surface defects such as surface welds, flow marks, and unevenness less noticeable, the ease of scratching or the effect of concealing scratches, etc., and grain specifications are also revealed. In fact, the fact is that grain is selected and processed based on experience and intuition.

[0004] For this reason, depending on the product, the expected gloss, high-grade feeling, difficulty in scratching, hiding effect of scratches, and effect of making molded appearance defects such as welds, flow marks, and unevenness less noticeable are not obtained. In addition, compensation costs such as correction of mold grain are generated, and the cost is often high. In addition, the poor molding appearance of the product can be improved to some extent by increasing the resin pressure in the mold to a high pressure to increase the pressure of the resin against the mold surface or by increasing the mold temperature. However, there is a problem that extra energy is required, the molding cycle is lengthened, and the molding cost of the product is increased. Therefore, if the appearance defect of the molded product can be made less noticeable by the grain, the method is simple, the molding cost can be reduced, and the merit is great.

[0005] As described above, the following methods are known in the related art in order to make molding appearance defects less noticeable due to graining. Sand blasting is applied to the grain where the weld is generated on the product to form fine irregularities, and diffuse reflection of light at the portion is increased to make the weld less noticeable (Japanese Patent Laid-Open No. 61-2).
No. 77419). The grain near the weld generation part of the product is made deeper (more than 60 μm) than the grain depth (50 μm) of other parts to improve the gas dispersibility of the weld part and make the weld less noticeable (Japanese Patent Application Laid-Open No. Sho 61). -277420). The grain of the part where the sink occurs in the product is made shallower than the surrounding grain, so that the resin surface can be easily transferred, the grain looks uniform, and the sink is not noticeable (Japanese Patent Laid-Open No. 8-300364).
issue).

[0006]

As described above, the mold surface is subjected to graining to impart a subtle shadow or moderate gloss or touch to the surface of the product, thereby giving the product a high-grade appearance and a plastic. It is possible to make the appearance defects such as welds, flow marks, and unevenness that occur on the product surface unique to the injection molding of the product less noticeable, and it is also possible to make the product less likely to be scratched. However, in order to obtain a product with good reproducibility, a high-grade appearance and feel, an effect that does not make the appearance of the product inconspicuous, and a resistance to scratching, the uneven spacing of unevenness, unevenness level, smooth surface finish It is necessary to define specifications such as Further, the above-mentioned conventional methods of the invention have the following problems.

In the case of the method described above, the method of applying sand blast to the part where the weld is generated has a lot of fine irregularities due to the sand blast, and as a result, irregular reflection on the surface of the product is increased, resulting in low gloss and lack of luxury. In addition, fine irregularities on the mold surface are caught, so that resin residue and dust easily accumulate, and the cleaning property is poor. In addition, the nail or the like is easily caught by the fine irregularities of the grain on the product surface and is easily damaged.

In the case of (1), since the grain near the weld generation portion is made deeper than 60 μm, the unevenness pattern on the product surface is also too coarse and lacks a sense of quality. Further, since the irregularities are deep, surface resin residue and dust easily accumulate, and the cleaning property is poor. Furthermore, depending on the mold structure, graining may occur when the mold is opened, resulting in uneven surface gloss of the product and impairing the appearance.

In the case of the method, although the grain is partially made shallow, the grain in other parts is the same as the conventional product, so that the grain is easily damaged and the detergency is poor. Also, from the concealing effect of poor appearance of the molding, it is difficult to match with the surroundings because the specifications of only the grain of the part where the appearance defect of the product occurs are different from the surroundings. There is a danger of becoming noticeable as a difference in gloss.

[0010] Accordingly, an object of the present invention is to provide a plastic grain product capable of stably molding a grain product having a high gloss on the surface of the product, having a high-grade appearance, and having a poor appearance of the molded product which is not conspicuous and not easily damaged. It is an object of the present invention to provide a mold and a method of manufacturing the mold.

[0011]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies on the correlation between the textured surface of the mold and the textured transfer surface of the product and the gloss, high-grade appearance, poor molding appearance and scratchiness of the product. Complex irregularities on the mold surface, the texture of the mold for injection molding of so-called textured products having a so-called matte texture, and the irregularities formed by etching the smooth mold surface without irregularities are blasted as described below. The blasting process is to adjust the interval between irregularities to 0.3 to 0.5 mm, which is easy for blast projection material to enter, and to adjust the ten-point average roughness (Rz) of the irregularities to 20 to 40 μm. Is a bead-shaped blasting material having a particle size of 100 to 200 mesh and a compressed air pressure of 0.2 to 0.4 MPa during blasting.
The unevenness due to etching and the undercut due to corrosion remaining on the surface of the grain unevenness is smoothed out, and as a finish, the grain unevenness is reduced at the time of blasting with the bead-shaped blasting material and at a compressed air pressure of 0.2 MPa or more. A particle size of 100 selected so as to enter the space sufficiently and to keep the blast shot material fine and not too coarse.
Add blasting with bead-like blasting material of ~ 200 mesh, crushing up to the remainder of the fine irregularities remaining in the recess inside the concave portion of the grain unevenness, and crushing the burrs of the bead-like blasting material itself, By providing a smooth bead-shaped surface of the textured surface only after blasting of the blasted blasted material, high quality gloss, high-grade appearance, poor appearance of molding, such as weld, flow mark, unevenness, etc. are less noticeable, and a textured product with excellent scratch resistance. A mold for forming grain products that can be formed and a method of manufacturing this mold have been completed.

More specifically, according to the first aspect of the present invention, in the method for producing a grain for forming a grain product, an etching treatment is applied to a smooth mold surface having no irregularities in forming a grain of a plastic injection mold. The unevenness of the embossed pattern formed is adjusted to a range of 0.3 to 0.5 mm between the embossed unevenness and a step of 20 to 40 μm, and then a bead-shaped blasting material is used to adjust the grain size to 100 to 200 μm. By setting the compressed air pressure at the time of meshing and blasting in the range of 0.2 to 0.4 MPa and blasting the uneven surface, fine unevenness due to etching remaining on the surface of the grain convex portion is crushed and further finished. At a compressed air pressure of not more than the compressed air pressure at the time of blasting with the bead-shaped blasting material and a compressed air pressure of not less than 0.2 MPa, and
A 0-mesh bead-shaped blasting material is projected onto the uneven surface of the grain, and blasting is applied to crush the burrs of the fine unevenness remaining inside the concave portion of the unevenness of the grain and the dents of the bead-shaped blasting material itself. In addition, a smooth bead-like surface of the blasting material having only a dent mark on the blast projection material is provided.

Further, in the invention according to claim 2,
In the mold for forming grain products, the gap between the irregularities of the grain pattern formed on the mold surface is 0.3 to 0.5 mm, and the surface of the grain pattern etched to the step of irregularities is 20 to 40 μm.
Using a bead-shaped blasting material having a particle size of 100 to 200 mesh, primary blasting is performed at a compressed air pressure of 0.2 to 0.4 MPa, and the surface of the primary blasted sibopattern is subjected to the primary blasting. Below the compressed air pressure, and 0.2 MPa or more, the blasting material is subjected to secondary blasting under the same conditions as during the primary blasting, and the uneven surface of the embossed surface is finished only with a smooth bead-like blasting material imprint. It is characterized by having.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a method of forming a grain on a mold surface according to the present invention will be described in detail, together with its operation, in comparison with a conventional method. FIG. 1 is a flowchart showing an outline of a conventional mold satin forming step. As a procedure for forming the matte texture of the mold 1, first, a resist 2 is formed on the mold surface (step 1), and then the mold surface which is not protected by the resist 2 is etched by etching and the mold grain pattern convex portion 3 is formed.
a and the mold concave pattern 3b are formed (step 2). In order to obtain more complicated unevenness, this process is repeated several times to form a complicated unevenness pattern on the mold surface.

However, in the etching process, the difference in the composition and grain boundaries in the mold material appears in the corrosiveness, so that the etched surface of the mold 1 has unevenness due to corrosion, which is uneven and uneven. There are cut-shaped corrosion holes 4a and, conversely, flat portions 4b remaining without being corroded. For this reason, a blasting material 5 having a random shape, such as alumina, is blasted on the etched surface of the mold 1 to smooth out the undercut corrosion holes 4a on the mold surface or to remove the flat portion 4b remaining without being corroded. By cutting, forming a large wavy embossed pattern,
The fine irregularities 6 on the surface of the irregular pattern are made uniform (step 3).

However, in this case, the surface of the obtained molded article is transferred to the fine irregularities 6 on the surface of the irregular pattern, resulting in an extremely matte appearance, resulting in an appearance problem that the product is too glossy and impairs a sense of quality. Or the product is easily damaged by contact with a nail or the like, that is, the product has poor scratch resistance. In addition, most of the molding appearance defects of the product are poor in transfer of the grain to the surroundings, and therefore, the gloss is increased to cause a difference in gloss from the surroundings. Therefore, in this state, the surface of the product on which the grain has been transferred is matte and dull, and the molding appearance defect is conspicuous.

For this purpose, a blast process using a bead-shaped blasting material 7 is further performed on the mold surface as a finish (step 4). Thereby, the fine irregularities 6 on the surface of the irregular pattern are crushed and smoothed, and the gloss of the product is enhanced. However, the distance between the textures of the bead-shaped blast projection material 7 is narrower than the particle size of the bead-shaped blast projection material 7, and the bead-shaped blast projection material 7 does not reach the inside of the concave portion of the textured blast projection material 5. The fine irregularities 6 cannot be crushed, or the blast pressure of the bead-like blasting material 7 is too high, and conversely, burrs are generated by the bead-like blasting material 7, so that the expected gloss and scratchiness of the product are reduced. Etc. are often not obtained.

FIG. 2 is a flow chart showing the outline of the step of forming the matte grain of the present invention. The grain forming process from step 1 to step 2 is the same as the conventional method.
However, in the present invention, the undercut-shaped corrosion holes 4a on the mold surface are formed only by the blasting with the bead-shaped blasting projections 7 in Step 4 without using the blasting with the random-shaped blasting projections 5 in Step 3. Or flatten the remaining flat part 4b without corrosion,
A large wavy embossed pattern is formed to prevent the formation of fine irregularities 6 on the surface of the irregular pattern by the conventional random-shaped blasting projection material 5 itself (step 4).

As a further finish, the compressed air pressure of not more than the pressure at the time of the blasting treatment by the bead-shaped blasting material 7 at step 4 and not less than 0.2 MPa, and
A blasting process is performed with a 0-mesh beaded blasting material 7 (step 5). In the present invention, the bead-shaped blasting material 7 is selected so that the spacing between the embossed portions and the particle size of the beaded blasting material 7 are selected so that the beaded blasting material 7 reaches the inside of the mold grain pattern concave portion 3b. The blast material 7 penetrates into the inside of the mold grain pattern recess 3b,
The undercut-shaped corrosion holes 4a remaining by etching in the mold concave portions 3b are sufficiently crushed.

The particle size of the bead-shaped blasting material 7 and the compressed air pressure at the time of blasting are determined so that the dent mark of the bead-shaped blasting material 7 is fine and not too coarse. Since the burrs are crushed and the surface is selected so as to have only a smooth bead-like blasted blasting material 7 imprint mark, a smooth uneven surface is obtained. Further, in order to sufficiently crush the burr due to the undercut-shaped corrosion holes 4a and the bead-shaped blasting material 7 itself by etching and to form a smooth bead-shaped blasting material 7 with only a dent trace, a bead-shaped surface is required. The compressed air pressure at the time of the blast processing by the blast projection material 7 may be made different by making step 4 high and step 5 low.

As described above, by increasing the gloss of the product despite the matte texture, it is possible to obtain a high-grade appearance, an effect of making the appearance of the molded product inconspicuous, and a hard to damage.
Further, since the surface has a smooth grain with crushed fine irregularities, the grain is less likely to be scorched, and the property of removing debris is high. Since there is little change over time of the grain due to long-term molding load and mold surface maintenance, it is possible to form a product having the same grain appearance stably over a long period of time.

The material of the blast projection material may be steel, plastic or the like in addition to glass, and is not particularly limited. Also, if the blasting time of the bead-shaped blasting material is made longer, the gloss of the mold grain may be adjusted using a random-shaped blasting material before the bead-shaped blasting treatment as in the conventional method, The gloss can also be adjusted by treating the grain surface of the mold with a beaded blasting material having a small particle diameter at a high compressed air pressure.

The mold material is not particularly limited, and may be an aluminum-based material, a titanium-based material, an electroformed material, or the like, in addition to a material generally used as a mold material, such as soft iron and beryllium copper. In addition, the resin molded by the injection mold according to the present invention is not limited to general-purpose resins such as polyolefin resin, polystyrene resin and ABS resin, or industrial resins such as polycarbonate resin and polyamide resin, and is also mixed with various resins. Or a mixture of a reinforcing agent, and there is no particular limitation.

[0024]

Embodiment 1 An embodiment of the present invention will be described with reference to FIGS. FIG. 3 is a schematic diagram of a product 10 formed by a test die having a surface provided with a grain according to the present invention, and shows positions where appearance defects such as welds, unevenness 11, sink marks, and flow marks 12 occur. FIG. 4 is a schematic enlarged view of the matte grain of the mold, and has a grain pattern irregularity interval, grain irregularity step (ten-point average roughness: Rz) at the time of evaluation of grain specifications.
The concept of the smoothness of the grain surface (the degree of crushing of fine irregularities) is shown.

The grain test mold material is made of S55C, the surface of which is etched according to a pattern called satin grain, a glass bead 200 mesh is compressed at a compressed air pressure of 0.3 MPa, and then a glass bead 200 mesh is formed. Blasting was performed at a compressed air pressure of 0.2 MPa using a blasting apparatus (manufactured by Fuji Seisakusho).

As shown in the schematic diagram of FIG. 4, the matte grain of the mold has a grain pattern irregularity interval of 0.33 mm, a grain irregularity step (ten-point average roughness: Rz) of 40.0 μm, and a smooth grain surface (fine irregularity). When observed with an electron microscope, the glass beads were sufficiently crushed by blasting.

Using the above test mold and polystyrene (SEHI119, Idemitsu Petrochemical) as a resin material, molding was performed with an injection molding machine (IS1300 manufactured by Toshiba Machine Co., Ltd.). The molded product 10 was high in glossiness on the product surface, had a high-grade appearance, and was free from outstanding defects such as welds, unevenness 11, sink marks, and flow marks 12, and was excellent in scratch resistance. Table 1 shows the grain specifications and product evaluations.

[0028]

Example 2 The same test mold and resin material as in Example 1 were used.
The grain forming method was changed, and alumina random 150 mesh was compressed at a compressed air pressure of 0.3 MPa.
The 0 mesh was blasted at a compressed air pressure of 0.4 MPa to perform molding. At this time, the matte texture of the test mold had a grain pattern interval of 0.3 as shown in the schematic diagram of FIG.
5 mm, uneven surface of the embossed pattern (ten-point average roughness: Rz)
When observed with an electron microscope, the smoothness of the grain surface (the degree of crushing of fine irregularities) was satisfactory because the crushing by glass bead blasting was sufficient.

The molded product 10 has high gloss on the surface of the product, has a high-grade appearance, and is a grain product having excellent appearance such as welds, unevenness 11, sink marks, flow marks 12, and excellent scratch resistance. Was done. Table 1 shows the grain specifications and product evaluations.

[0030]

Embodiment 3 Using the same test mold, grain forming method and resin material as in Embodiment 2, molding was carried out by increasing only the emboss pattern uneven pitch in the grain specification. The matte texture of the test mold at this time had a grain pattern irregularity interval of 0.50 mm,
29. The unevenness of the embossed pattern (ten-point average roughness: Rz) is 29.
5 μm, smoothness of the grain surface (how fine irregularities are crushed)
Observed with an electron microscope, crushing by glass bead blast was sufficient and good. Molded product 10
Has a high gloss and high quality on the product side.
An appearance defect such as unevenness 11, sink mark, and flow mark 12 was not conspicuous, and a grain product excellent in scratch resistance was obtained. Table 1 shows the grain specifications and product evaluations.

[0031]

Comparative Example 1 The same test mold and resin material as in Example 1 were used.
Molding was performed using a grain under conditions where only blasting was not performed as etching only during grain formation. At this time, the matte of the test mold had a grain pattern of 0.32 mm.
The unevenness of the grain pattern (ten-point average roughness: Rz) is 25.0.
μm, smoothness of the grain surface (the degree of crushing of fine irregularities)
When observed with an electron microscope, the sample was not smooth with many fine irregularities due to etching.

The molded product 10 had no gloss on the product surface, lacked a sense of quality, and had poor appearance such as welds, unevenness 11, sink marks, and flow marks 12, as compared with Example 1, and the product value was significantly reduced. In addition, since fine irregularities were easily deformed by the nails to leave marks, the scratch resistance was remarkably inferior to the examples. Table 1 shows the grain specifications and product evaluations.

[0033]

Comparative Example 2 The same test mold and resin material as in Example 1 were used.
After etching, blasting is performed using alumina random 150
Molding was performed as a crimp under the condition that the mesh was only compressed air pressure of 0.3 MPa and the blast treatment with glass beads was not applied. At this time, Nashiji Shibo of the test mold is
The unevenness of the embossed pattern was 0.35 mm, the unevenness of the embossed pattern (ten-point average roughness: Rz) was 26.2 μm, and the smoothness of the embossed surface (the degree of crushing of the fine unevenness) was observed with an electron microscope. Many fine irregularities due to blasting were observed and were not smooth.

The molded product 10 lacked the glossiness of the product surface and lacked a sense of quality, and had poor appearance such as welds, unevenness 11, sink marks, flow marks 12, etc. as compared with Example 1, and the product value was significantly reduced. In addition, since fine irregularities were easily deformed by the nails to leave marks, the scratch resistance was remarkably inferior to the examples. Table 1 shows the grain specifications and product evaluations.

[0035]

[Comparative Example 3] Among the blasting treatments of the grain forming method, the treatment with 100 mesh of glass beads was performed by lowering the compressed air pressure to 0.2 MPa and shortening the treatment time so that the surface of the grain was smoothed (the degree of crushing of fine irregularities). The molding was carried out using the same test mold and resin material except that the value of) was lowered. The matte texture of the test mold at this time had a grain pattern irregularity interval of 0.29 mm, and a grain irregularity step (ten-point average roughness:
Rz) was 28.2 μm, and the smoothness of the grain surface (the degree of crushing of fine irregularities) was observed with an electron microscope. The blast treatment with glass beads was insufficient and many fine irregularities due to alumina random blast were observed. Was not smooth.

The molded product 10 lacked the glossiness of the product surface and lacked a sense of quality, and had poor appearance such as welds, unevenness 11, sink marks, and flow marks 12, as compared with Example 1, and the product value was significantly reduced. In addition, since fine irregularities were easily deformed by the nails to leave marks, the scratch resistance was remarkably inferior to the examples. Table 1 shows the grain specifications and product evaluations.

[0037]

Comparative Example 4 Molding was performed using the same test mold, grain forming method, and resin material while increasing the grain pattern uneven pitch and grain pattern step (ten-point average roughness: Rz) among grain specifications. The matte texture of the test mold at this time has a grain pattern irregularity interval of 0.61 mm, a grain irregularity step (ten-point average roughness: Rz) of 51.2 μm, and a smooth grain surface (the degree of crushing of the fine irregularities). Observation with an electron microscope showed that the crushing by glass bead blast was sufficient and good.

[0038] The molded product 10 has coarse grain pattern on the product surface and lacks a sense of quality.
The appearance defects such as the flow mark 12 were more conspicuous than in Example 1, and the product value was significantly reduced. The scratch resistance of the product was good. Table 1 shows the grain specifications and product evaluations.

[0039]

Comparative Example 5 Using the same test mold, grain forming method, and resin material, molding was performed with the grain pattern unevenness pitch and grain pattern unevenness step (ten-point average roughness: Rz) of the grain specifications being reduced. The matte texture of the test mold at this time has a grain pattern irregularity interval of 0.2 mm, a grain irregularity step (ten-point average roughness: Rz) of 21.3 μm, and smoothness of the grain surface (the degree of crushing of the fine irregularities). Observation with an electron microscope showed that the crushing by glass bead blast was sufficient and good. The molded product 10 had outstanding appearance defects such as welds, unevenness 11, sink marks, and flow marks 12 as compared to Example 1, and the product value was significantly reduced. The scratch resistance of the product was good. Table 1 shows the grain specifications and product evaluations.

[0040]

[Table 1] (Margin below) Note 1: The evaluation of the smoothness of the grain surface (the degree of crushing of the fine irregularities) was evaluated as follows: The fine irregularities on the grain surface were sufficiently crushed as shown in the end stage of step 4 in FIG. Was marked as x when there were many residues. Note 2: The case where the appearance defect of the product surface is not easily confirmed visually is indicated by “○”, and the case where the appearance defect is easily observed is indicated by “×”. Note 3: A nail that does not easily form a scar is rated as ○, and a nail that easily forms a scar is rated as ×.

[0041]

As described above, according to the present invention, the unevenness formed by etching the smooth mold surface having no unevenness is (1) the unevenness interval is 0.3 to 0.5 mm and the unevenness is 0.3 to 0.5 mm. The ten-point average roughness (Rz) is adjusted to a range of 20 to 40 μm, and then the blast treatment to be applied to the uneven surface is performed by (2) a bead-shaped blasting material such as glass with a particle diameter of 100 to 2 μm.
00 mesh, compressed air pressure during blasting 0.2 ~
Perform at 0.4MPa, and finish blasting
(3) A bead-shaped blasting material such as glass, having a particle size of 100 to 200 mesh, and a compressed air pressure at the time of blasting of not more than 0.2 MPa or more than the compressed air pressure at the time of the blasting treatment described in (2) above. By reducing the fine irregularities due to the etching remaining on the surface of the grain, and manufacturing the mold by a simple mold crimping method with a smooth grain surface only after the dent of the bead-like blasting material, By using a mold, it is possible to stably mold a grain product having a high glossiness on the product surface, a high-grade appearance, inconspicuous appearance defects, and excellent scratch resistance, which is significant. .

[Brief description of the drawings]

FIG. 1 is a flowchart showing an example of a step of forming a matte texture of a mold according to a conventional method.

FIG. 2 is a flowchart showing an example of a step of forming a matte texture of a mold according to the present invention.

FIG. 3 is a schematic diagram of products of Examples and Comparative Examples.

FIG. 4 is a schematic enlarged view of a matte grain of the mold.

[Explanation of symbols]

 Reference Signs List 1 mold 2 resist 3a mold grain pattern convex part 3b mold grain pattern concave part 4a undercut-shaped corrosion hole 4b flat part left without being corroded 5 random-shaped blasting material 6 fine irregularities on grain surface pattern 7 beads 8 Blast blasting material of bead 8 Imprint marks by bead blasting material 10 Molded product by Shibotest mold 11 Weld, unevenness 12 Sink, flow mark

Claims (2)

[Claims] 1. In forming a grain of a plastic injection mold, the grain of a grain pattern formed by etching a smooth mold surface having no unevenness is adjusted to have an interval of the grain of 0.3 to 0.5 mm. The unevenness is adjusted to a range of 20 to 40 μm, and then a bead-shaped blasting material is used.
By blasting the irregular surface by setting the compressed air pressure at the time of blasting to a range of 0.2 to 0.4 MPa, fine irregularities due to etching remaining on the surface of the grain convex portion are crushed. , And as a finish,
At a compressed air pressure of not more than the compressed air pressure at the time of blasting by the bead-shaped blasting material, and a compressed air pressure of 0.2 MPa or more, the bead-shaped blasting material having a particle size of 100 to 200 mesh is projected on the embossed surface. Adds blasting treatment and crushes the burrs of the fine irregularities remaining inside the concave part of the grain unevenness and the dents of the bead-like blasting material itself, leaving only the smooth bead-like blasting material dent mark surface A method for producing a mold for forming grain products, characterized in that: 2. The gap between the irregularities of the grain pattern formed on the surface of the mold is 0.3 to 0.5 mm, and the step of the irregularities is 20 to 40 μm.
The surface of the Sibopattern etched to a particle size of 100 to 2
Using a 00 mesh beaded blasting material,
The primary blasting is performed at a compressed air pressure of 2 to 0.4 MPa, and the surface of the primary blasted sibopattern is not more than the compressed air pressure at the time of the primary blasting and 0.2 MPa or more, and the blasting material is the primary blasting material. A mold for forming grain products, which is subjected to secondary blasting under the same conditions as at the time of blasting, so that the uneven surface of the grain is finished only with a smooth bead-like blasted blasting mark.