Manufacturing method of mold and manufacturing method of precision decorated resin molded product

Abstract

To provide a precision decorative resin molded product, a mold, a method for manufacturing the mold, and a method for manufacturing the precision decorative resin molded product for precisely decorating conventional molds with carbon patterns.SOLUTION: A precision decorative resin molded product is a resin molded product with a carbon pattern. The carbon pattern has a warp bundle pattern and a weft bundle pattern. A method for manufacturing a mold includes steps of determining to which part of the resin molded product a twill weave carbon pattern is applied to generate CAD data for the molded product, and operating a cutting tool to form the precision decorative resin molded product with the carbon pattern by setting CAM data so that a cusp created by cutting tool paths that are parallel at a predetermined interval and adjacent to each other is set to have a carbon fiber pattern so as to create the carbon fiber pattern in a bundle longitudinal direction of each of warp and weft bundles.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a precision-decorated resin molded product, a mold, a method for manufacturing a mold, and a method for manufacturing a precision-decorated resin molded product, and in particular to a product using a carbon pattern and a method for manufacturing the same. [Background technology]

[0002] Carbon fiber reinforced plastics have excellent mechanical properties, but because their unit price per unit volume is high, it is not easy to use them in all parts from a cost perspective. On the other hand, carbon fiber reinforced plastics have unique designs that are different from metals and resins, so there is a very high demand for designs that resemble carbon fiber reinforced plastics (so-called carbon patterns).

[0003] For example, Patent Document 1 discloses an example in which a carbon pattern is used in the dial structure, in which a character board made of PP or PC material is wrapped with a sheet material or the like on which unevenness reminiscent of carbon fiber reinforced plastic is printed, making it look as if the dial is made of carbon fiber reinforced plastic. Moreover, Patent Document 2 proposes directly irradiating a resin molded product with a laser to process it into a carbon fiber-like material. Furthermore, in Patent Document 3, an attempt is made to reproduce a carbon pattern by engraving a mold using laser processing. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2015-283430 A [Patent Document 2] JP 2012-176744 A [Patent Document 3] Patent No. 6765819 Summary of the Invention [Problem to be solved by the invention]

[0005] However, manufacturing the character base and the uneven portion of a dial that uses a carbon pattern from separate parts requires multiple design processes, manufacturing processes and parts, which inevitably results in increased costs in both material purchases and manufacturing labor. As in Patent Document 2, if processing is performed after resin molding, the number of steps is clearly increased. This is because, even if laser processing is performed in addition to cutting processing as in Patent Document 3, the process and cost are increased in terms of preparing a laser processing tool and adding another process. do The point remains the same.

[0006] Therefore, as a result of intensive research, the applicant decided to adopt a carbon fiber reinforced plastic pattern design at the mold design stage when manufacturing resin molded products. Of course, the number of steps in the mold design and manufacturing process will increase because a decoration process is added to the mold, but if carbon pattern sheets are continuously attached, the impact of multiple parts and multiple processes in retrofitting will increase as the number of shots in one mold increases, so it goes without saying that adding a decoration process to the mold is desirable.

[0007] An object of the present invention is to provide a precision-decorated resin molded product, a mold, a method for manufacturing a mold, and a method for manufacturing a precision-decorated resin molded product, which are precisely decorated with a carbon pattern using conventional molds. [Means for solving the problem]

[0008] The precision-decorated resin molded product according to the present invention is a resin molded product having a carbon pattern, the carbon pattern comprising a warp bundle pattern and a weft bundle pattern. The warp and weft patterns of the precision decorated resin molded product have carbon fiber-like patterns. The precision decorated resin molded product is characterized in that the carbon pattern warp bundle pattern and weft bundle pattern are twill-woven. The mold according to the present invention is used to mold the above-described precision-decorated resin molded product. The manufacturing method of the mold involves the steps of determining which part of the resin molded product to apply the twill carbon pattern to and generating CAD data for the molded product. A carbon fiber pattern is engraved in the longitudinal direction of each of the warp and weft bundles, and the CAM data is set so that the cusps created by cutting adjacent parallel tool paths at specified intervals form a carbon fiber pattern.Then, the cutting tool is operated to form a precisely decorated resin molded product with a carbon pattern. Manufacturing method of precision decorated resin molded products: The method uses an injection molding machine equipped with a mold manufactured by the method described above. In this embodiment, a twill weave is shown as an example, but the fabric may be formed in a plain weave or satin weave. Effect of the Invention

[0009] By using the precision-decorated resin molded product, mold, mold manufacturing method, and precision-decorated resin molded product manufacturing method for precision decoration with carbon patterns according to the present invention, a carbon pattern molded product can be obtained in a single shot, thereby reducing labor and costs, and it becomes possible to freely design, manufacture, and provide molded products. [Brief description of the drawings]

[0010] [Figure 1] 1 is a diagram showing the configuration of an automobile part formed from a precision decorated resin molded product according to the present invention; [Diagram 2] 1 is a diagram showing the configuration of a precision decorated resin molded product according to the present invention; [Diagram 3] 1 is a conceptual diagram of a twill weave constituting a carbon pattern that is decorated on a precision-decorated resin molded product according to the present invention. FIG. [Figure 4] 1 is a conceptual diagram of a machining center for manufacturing a mold for forming a precision decorated resin molded product according to the present invention. [Diagram 5] 1 is a conceptual diagram of a mold for forming a precision-decorated resin molded product according to the present invention. [Figure 6] 1 is a configuration diagram showing a method for manufacturing a mold for forming a precision-decorated resin molded product according to the present invention. [Figure 7] 1 is a block diagram showing a method for manufacturing a precision-decorated resin molded product according to the present invention; [Figure 8] FIG. 1 is a diagram showing the configuration of a conventional carbon fiber reinforced plastic. [Figure 9] FIG. 1 is a diagram showing the structure of a carbon sheet similar to conventional carbon fiber reinforced plastic. [Figure 10] FIG. 1 is an enlarged view of a conventional carbon fiber reinforced plastic. [Figure 11] 1 is an enlarged view of a precision-decorated resin molded product according to the present invention. [Figure 12] FIG. 2 is an enlarged view of a carbon sheet similar to conventional carbon fiber reinforced plastic. [Figure 13] FIG. 4 is a diagram showing height measurement of the precision-decorated resin molded product according to the present invention using a laser microscope. [Figure 14] FIG. 1 is a diagram showing height measurement of conventional carbon fiber reinforced plastics using a laser microscope. [Figure 15] FIG. 1 is a diagram showing height measurements of a carbon sheet similar to conventional carbon fiber reinforced plastics, taken using a laser microscope. [Figure 16] FIG. 4 is a diagram showing measurement points for width pitch of a precision-decorated resin molded product according to the present invention using a laser microscope. [Figure 17] FIG. 1 is a diagram indicating measurement points for width pitch of a conventional carbon fiber reinforced plastic using a laser microscope. [Figure 18] FIG. 1 is a diagram indicating measurement points for width pitch of a carbon sheet similar to a conventional carbon fiber reinforced plastic, using a laser microscope. [Figure 19] 2 is a further enlarged view of the precision-decorated resin molded product according to the present invention. FIG. [Figure 20] FIG. 2 is a further enlarged view of a conventional carbon fiber reinforced plastic. [Figure 21] FIG. 2 is a further enlarged view of a carbon sheet similar to conventional carbon fiber reinforced plastic. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Next, an embodiment of the present invention will be described in detail with reference to the drawings. In all the drawings described below, the same components are denoted by the same reference numerals, and the description thereof will be omitted as appropriate.

[0012] (Embodiment 1) The first embodiment is a configuration of a precision decorated resin molded product, and examples of the precision decorated resin molded product include an exterior cover for an audio product as a housing for an electric product, a bumper and door mirror as an exterior part of an automobile, and a dashboard 4, an instrument panel 6, a center cluster 8, a steering wheel 10, a meter 12, a shift lever 13, etc. as an interior part 2 of an automobile. All or a part of these can be composed of the precision decorated resin molded product.

[0013] FIG. 2 is a perspective view of a resin molded product showing a part of the interior part 2 of the automobile shown in FIG. 1. The resin molded product 16 shown in FIG. 2 showing a part of the interior part of the automobile is made of polycarbonate. It has a shape imitating twill carbon fiber, and the mold for molding this molded product is formed by cutting with a ball end mill with a tip of R0.5, and the surface of the molded product has a glossy appearance. The shape is designed to create a woven feel by forming a cusp that rises 0.1 mm in the center on a flat surface. As shown in FIG. 3, twill weave is woven by repeatedly passing a warp bundle 18 over two or three weft bundles 20 and then under one weft bundle 20. It is adopted as one of the weaving methods for carbon fiber. A carbon fiber-like pattern is engraved on the warp bundle 18 and the weft bundle 20.

[0014] The resin molded product 16 is molded by injecting and filling polycarbonate resin into a mold having a cavity with a portion for forming the carbon handle 14. Fig. 4 is an explanatory diagram showing a machining center 22 that processes the mold according to the embodiment. The machining center 22 has a machine tool main body 24 and a control device 26.

[0015] The machine tool body 24 performs cutting on the surface of the workpiece 28 to be machined, and forms a cavity, which is a component of a mold. The machine tool body 24 has a spindle 32 that rotatably supports a cutting tool 30, and a well-known means for moving the workpiece 28 three-dimensionally.

[0016] An end mill, particularly a ball end mill, is preferably used as the cutting tool 30. The spindle 32 rotates the cutting tool 30 about the Z axis, and the well-known means moves the workpiece 28 freely in the X, Y and Z directions.

[0017] The control device 26 is composed of an electronic computer in which a central integrated circuit, an internal memory device, an external memory device, an external interface, and a cutting tool interface are connected by internal wiring, and controls the machine tool body 24 according to NC data. The NC data includes a tool path, which is the movement path of the cutting tool 30 defined by the amount of movement in the X direction, the amount of movement in the Y direction, the amount of movement in the Z direction, the rotation speed of the spindle, the feed rate in the X direction, the feed rate in the Y direction, and the movement rate in the Z direction. The control device 26 moves the workpiece 28 according to the NC data, so that a cavity and a carbon pattern can be cut into the surface of the workpiece 28.

[0018] Here, the process of creating NC data is an important process of the present invention. The tool path is designed by a CAD / CAM system, and the twill weave structure is designed by CAD. As for the tool path, a ball end mill is used in the warp and weft directions to form a tool path in the longitudinal direction of the threads at a predetermined interval, and a realistic carbon pattern can be reproduced on the mold surface by drawing carbon fiber-like traces on the mold surface. Here, the diameter of the ball end mill is preferably R0.2 to R2, and the tool path interval is 25 μm to 500 μm. Furthermore, the shape height from the highest part to the lowest part of the carbon fiber-like shape is 0.05 mm to 0.2 mm, so that a realistic carbon pattern can be reproduced on the mold surface.

[0019] 5 is a perspective view showing the entire mold 40 according to the present invention. A carbon pattern is cut into the inner surface of the mold 40 (not shown) which is inside the mold 40 to provide a carbon pattern forming portion. The carbon pattern forming portion is cut into an inverted shape of the carbon pattern so that the carbon pattern is formed on the surface of the resin molded product.

[0020] Next, the manufacturing method of the mold and the manufacturing method of the molded product will be described with reference to Figures 6 and 7. Figure 6 shows a cross section indicated by arrow A in Figure 3. By performing cutting processing on the surface of the mold blank 50 as shown in Figure 6(b), a mold 40 is manufactured so as to mold the twill-shaped carbon fiber pattern shown in Figure 3 into the molded product.

[0021] First, we decide which parts of the resin molded product will have the twill carbon pattern applied, and then generate CAD data for the molded product, including the parts that will have the twill carbon pattern and the other parts.

[0022] Secondly, a tool path is generated from the CAD data using a CAM system. The tool path is set so that the ball end mill moves in the longitudinal direction of the warp and weft bundles, and further, it is preferable to set the tool path so that the cusps formed by cutting adjacent parallel tool paths at a predetermined interval form a carbon fiber pattern so that a carbon fiber pattern is engraved in the longitudinal direction of each of the warp and weft bundles. In order to realize these, the diameter of the ball end mill 57 is preferably R0.2 to R2, and the tool path interval is preferably selected to be 25 μm to 500 μm. Furthermore, the tool path is designed to move along the fiber length of the twill carbon fiber shape, that is, the longitudinal direction. For this reason, in FIG. 6(b), the carbon fiber is cut so that a cusp 54 representing a carbon fiber with a low cusp height and a cusp 58 with a high cusp height that is the boundary between the longitudinal direction and the lateral direction are provided in the lateral direction of the carbon fiber. A cross section of the cut mold 40 is shown. In this way, a cut surface is formed. Here, a high cusp height indicates the lines on both sides of the weft and warp bundles of the carbon pattern, and a low cusp height indicates each individual carbon fiber pattern.

[0023] Meanwhile, the cut mold 40 is incorporated into an injection molding machine, and polycarbonate resin is injected into the cavity formed by the mold 40. When the polycarbonate resin cools and solidifies, a resin molded product 62 is formed. As a result, a resin molded product is obtained that displays a twill-like design made of carbon fiber.

[0024] Specific examples will now be described.

[0025] The resin molded product molded as an example is shown in Figure 2. Polycarbonate is used as the resin, and the mold is machined so that a twill carbon pattern is shown on the surface when molded. Machining Center It is processed with Machining Center The tool used is a ball end mill with a tip radius R of 0.2mm to 2mm, which is the optimal value for the design target, and this gives the carbon handle a glossy finish. Furthermore, although the overall shape is rectangular, the center is shaped to be 0.1mm higher than the ends, creating a woven look.

[0026] Comparative Example 1 is shown in FIG. 8 and is a carbon fiber reinforced plastic (CFRP) formed using acrylic fiber whose main raw material is acrylonitrile, so-called carbon fiber. It is a twill weave sample product, and the bundles of fibers give it thin lines and a glossy finish.

[0027] Comparative Example 2 is a carbon sheet shown in Fig. 9, and is made of polyvinyl chloride. It is a polyvinyl chloride sheet with a carbon-like texture, and the carbon shown is twill weave, with clear unevenness on the surface. The lines are thick, the tips are thin, and the center is bulged, creating an uneven appearance on a flat surface.

[0028] Example 1 For the above-mentioned Example, Comparative Example 1, and Comparative Example 2 (detailed measurement locations are shown in Figures 10, 11, and 12), the surface roughness (Ra), arithmetic mean curvature (Spc), number of peaks per unit area (Spd), pitch, and depth were measured using a Keyence laser microscope, and the results are shown in Table 1. Surface roughness (Ra) indicates the magnitude of surface irregularities, arithmetic mean curvature indicates the roundness of the peaks and thus indicates the degree of gloss, and depth indicates groove depth. The number of peaks per unit area indicates the number of cusps within the same area. Pitch indicates the distance between the pitches per processing or shape; if this distance is uniform, it will be glossy, and if it is random, it will be uneven. [Table 1] Table 1 shows the results of measurements taken at 480x magnification, with the upper row showing the warp threads and the lower row showing the weft threads.

[0029] Example 2 In Example 2, the height difference between the warp and weft yarns was measured using the same laser microscope for the Example, Comparative Example 1, and Comparative Example 2, and the results are shown in Table 2. The measurement data is shown in FIG. 13 for the Example, FIG. 14 for Comparative Example 1, and FIG. 15 for Comparative Example 2. [Table 2] The difference in height of the embodiment of the present invention is the largest, and a three-dimensional effect is expressed. Both the embodiment and comparative example 1 have clear concaves and convexes, and a three-dimensional effect is expressed. This is because grooves can be seen in both the concaves and convexities of both of these fabrics, and these grooves express the fibers, thereby expressing a three-dimensional effect. This expresses the ends of the warp and weft bundles. On the other hand, in Comparative Example 2, although the grooves can be seen, there is variation in the protrusions, and therefore, although the carbon pattern itself can be seen, the three-dimensional effect cannot be fully expressed.

[0030] Example 3 In Example 3, the width pitch of the thin lines in the warp yarn portion of the carbon fibers or equivalents was measured using the same laser microscope for the Example, Comparative Example 1, and Comparative Example 2. The measurement results are shown in Table 3. The measurement points are shown in Figure 16 for the Example, Figure 17 for Comparative Example 1, and Figure 18 for Comparative Example 2. [Table 3] The fiber width of Comparative Example 1 is the smallest, followed by that of the Example, and the fiber width of the sheet is the largest. This pitch represents the width of a single fiber in the carbon fiber pattern, and the narrower the pitch, the higher the reproducibility of the carbon fiber.

[0031] Example 4 In Example 4, gloss check and spectrometry were performed for the above-mentioned Example, Comparative Example 1, and Comparative Example 2. The gloss check was performed by measuring the glossiness at a standard angle of incidence of 60°. A gloss checker manufactured by Horiba Ltd. was used as the measuring device. The spectrometry was performed at an incidence angle of 0° using a spectrometry device manufactured by Konica Minolta, and a gloss check was also performed at an incidence angle of 8°. The spectrometry was performed in a brightness L mode, which indicates a numerical value when black is 0 and white is 100, an a mode in which green is negative and red is positive, and a b mode in which blue is negative and yellow is positive. [Table 4]

[0032] In terms of brightness, Comparative Example 1 is the brightest, followed by the Examples. In mode a, Comparative Example 1 has a reddish tint, whereas the Examples and Comparative Example 2 have a greenish tint. In mode b, Comparative Example 1 has a yellowish tint, whereas the Examples and Comparative Example 2 have a bluish tint.

[0033] The gloss check revealed that the Example had the highest gloss both at 8° measured with a spectrophotometer and at 60° measured with a gloss checker.

[0034] Example 5 In Example 5, the above-mentioned Example, Comparative Example 1, and Comparative Example 2 were subjected to gloss checks using different measuring instruments. The measuring instrument used was a gloss checker made by Nippon Denshoku Industries Co., Ltd., VG7000. The gloss check was performed by measuring the glossiness at standard angles of incidence of 20°, 60°, and 85°. The results are shown in Table 5. [Table 5] In both cases, the gloss measurement values ​​of the Examples were high, being several ten times that of Comparative Example 1. It was also clear that the gloss increased as the incidence angle increased, and that the gloss level was particularly high at 85°.

[0035] Example 6 In Example 6, camera image analysis was performed on the above-mentioned Example, Comparative Example 1, and Comparative Example 2. Regarding the low-magnification photographs, a low-magnification photograph of the Example is shown in Fig. 19, a low-magnification photograph of Comparative Example 1 is shown in Fig. 20, and a low-magnification photograph of Comparative Example 2 is shown in Fig. 21. The high-magnification photographs are shown in Figs. 10, 11, and 12.

[0036] Table 6 shows the image entropy, which indicates the degree of gloss gradation calculated from these photographs and is calculated from the number of tones in the image, the probability of the tones appearing, and the number of pixels, and the contrast, which indicates the degree of difference between black and white and is calculated from the maximum and minimum brightness values ​​in the image. [Table 6] Regarding the entropy of the image, the Example exhibits the highest entropy in the ranking of the Example, Comparative Example 2, and Comparative Example 1. In addition, regarding the contrast, the Example exhibits the highest contrast at high magnification, and is second only to Comparative Example 2 at low magnification.

[0037] This example shows that the use of the present invention can increase image entropy and contrast in particular. Furthermore, from the above examples, it was found that in order to make the carbon pattern resemble real carbon fiber, the unevenness of the grooves that represent the carbon fiber must be clearly expressed to express the fiber-like appearance and make it look more like carbon fiber, and further, the three-dimensional effect can be clearly expressed by adding contrast to the unevenness in each certain section, and the brilliance can be increased by providing a uniform moderate gloss. [Explanation of symbols]

[0038] 2. Automotive interior parts 4. Dashboard 6 Instrument Panel 8 Center Cluster 10. Steering Wheel 12 meters 13 Shift lever 14 Carbon Pattern 16 Resin molded products 18 Warp bundle 20 Weft bundle 22 Machining Center 24 Machine tool body 26 Control device 28 Work 30 cutting tools 32 Main axis 40 Mold 50 Mold Material 54 Cusp 57 Ball end mill 58 High Cusp 62 Resin molded products

Claims

1. A process of determining which part of the resin molded product is to have a carbon pattern and generating CAD data for the molded product; This method of manufacturing a mold forms a precisely decorated resin molded product with a carbon pattern by operating a cutting tool and setting CAM data so that the cusps created by cutting adjacent parallel tool paths at a specified interval form a carbon fiber pattern in the longitudinal direction of each warp bundle and weft bundle.

2. A method for manufacturing a precisely decorated resin molded product using an injection molding machine equipped with a mold manufactured by the method according to claim 1.

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