JP2013256091A - Resin molding, method of manufacturing the same and printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate manufacture of a molding by reducing color tone change called irregularity produced on an appearance surface of the molding with projections or depressions formed on a non-appearance surface or the projections or depressions formed on the appearance surface and by simplifying machining of a die to be transferred when producing the molding.SOLUTION: A non-appearance surface has a pattern of repetitively formed protruded parts where unit forms with two or more spherical crowns having different curvature radii combined are continuously superposed in addition to projections or depressions.

Description

  The present invention relates to a plate-shaped resin molded product. More specifically, the present invention relates to a resin molded product by plate-like injection molding in which the appearance quality is important, a manufacturing method thereof, and a printer.

  Plate-shaped resin molded products have rib-like protrusions for reinforcement and positioning on the non-external surface, protrusions or depressions such as steps due to the ejector pins, and an arrow shape for guiding the product functions to the user on the external surface. There may be various uneven shapes such as protrusions or depressions. The appearance surface referred to here is a surface that requires a quality of appearance in order to touch the user's eyes, and the non-appearance surface refers to the back surface of the appearance surface.

  At the time of injection molding, the flow of resin injected into the mold cavity from the injection gate is disturbed by the protrusions or depressions. As a result, an appearance surface behind the protrusions or depressions on the non-appearance surface, or a portion with a changed color tone called unevenness may occur near the projections or depressions on the appearance surface.

  As a means for avoiding a change in appearance color tone, particularly jetting (resin flow marks caused by an increase in resin flow rate), a method described in Patent Document 1 has been proposed. This is a method of molding using a molding die provided with a resin flow rate lowering means such as a concavo-convex shape at a location where the resin flow rate increases with respect to the cavity forming the non-appearance surface.

JP 2001-277303 A

  However, the method of Patent Document 1 suppresses an increase in the resin flow rate due to the depression due to the concave and convex shape of the V-shaped groove, and improves an appearance defect caused by an increase in the resin flow rate such as jetting. However, the problem that the unevenness | corrugation by the uneven | corrugated shape of a hollow or a V-shaped groove | channel will generate | occur | produce on the molded article surface remains.

  Further, as a conventionally known method, there is a method of increasing the mold temperature or the resin temperature. However, when the mold temperature is increased, it is necessary to lengthen the cooling time, the molding cycle time is lengthened, and the productivity is deteriorated. Even when the resin temperature is increased, the molding cycle time is similarly increased, and the productivity is deteriorated.

  An object of the present invention is to reduce a change in color tone generated on an appearance surface called unevenness of a molded product having protrusions or depressions on a non-appearance surface, or projections or depressions on an appearance surface. Furthermore, it aims at making manufacture of a molded product easy by simplifying the process of the metal mold | die for shape | molding a resin molded product.

  The resin molded product of the present invention has an external surface and a non-external surface, and a thickness between the external surface and the non-external surface is 3 mm or less, and the external surface has protrusions or depressions, and In the resin molded product in which at least one of a protrusion or a depression from a reference surface is formed on the non-appearance surface, the non-appearance surface has a unit shape in which two or more spherical crowns having different curvature radii are combined. Further, it is characterized in that a repeated pattern of convex portions that are continuously overlapped is further formed.

  The method for producing a resin molded product of the present invention is a method for producing a resin molded product for producing a resin molded product by transferring the shape of the surface of the mold by pouring resin into the mold. After forming a groove by scanning a first ball end mill having a tool surface made of a spherical surface having a first diameter on the surface of the mold having depressions for forming ribs, Scanning a second ball end mill having a tool surface having a small diameter spherical surface to form a further groove inside the groove, wherein the step of forming the groove comprises the step of forming the spherical surface of the first ball end mill. Transfer is performed by scanning the second ball end mill so that the line connecting the center of the sphere and the center of the spherical surface of the second ball end mill is parallel to the normal direction of the mold surface. Of curvature radius Two or more units shape combining a spherical crown made was continuously overlaid, and forming a recess repetitive pattern is formed in the convex portion.

  According to the present invention, it is possible to reduce unevenness occurring on the appearance surface of a non-appearance surface protrusion or depression, or a resin molded product having an appearance surface protrusion or depression. Moreover, the manufacturing method of the resin molded product of this invention can simplify the process of a metal mold | die, and can make manufacture of a resin molded product easy.

The figure which shows embodiment of this invention Diagram showing the position and size of the arc shape The figure which shows an example of the manufacturing method of the resin molded product of this invention Diagram showing comparative shape Diagram showing how resin flows during injection Diagram showing how resin flows during injection Diagram showing how resin flows during injection Diagram explaining unevenness that appears on the exterior The figure which shows the shape of an Example 1 is a perspective view of a composite printer including a document reading apparatus to which the present invention is applied. The perspective view of the state which opened the document cover to which this invention is applied

  FIG. 1 is a diagram of a plate-shaped resin molded product having ribs, which is a typical embodiment of the present invention. FIG. 1A is a schematic view of a resin molded product, and FIG. 1B is a cross-sectional view taken along line A-A ′ of FIG. FIG.1 (c) is BB 'sectional drawing of Fig.1 (a). In FIG. 1, 1 is a plate-shaped resin molded product, 101 is an external surface having a mirror surface or a textured surface, 102 is a non-external surface, and 2 is a rib that is a protrusion protruding from the non-external surface 102 of the resin molded product. is there. The rib 2, which is a projection that protrudes from the thin plate-like non-appearance surface, has a long side and a short side at least at the base portion. On the non-appearance surface 102, a repeated pattern 3 of convex portions is formed by continuously superimposing unit shapes obtained by combining two or more spherical crowns having different curvature radii. By forming a repeating pattern of convex portions on the non-appearance surface, which is formed by continuously superimposing unit shapes combining two or more spherical crowns having different curvature radii, it is possible to reduce unevenness of the appearance surface. . The present invention has been made on the basis of the results clarified by the following resin flow visualization experiment.

  FIGS. 5A to 5C are views showing a state of resin flow at the time of injection in a molded product having rib-like protrusions protruding on the non-appearance surface. FIGS. 6A to 6C are views showing the state of resin flow at the time of injection in a molded product having a depression on the non-appearance surface. Furthermore, FIG.5 (d)-(f) is a figure which shows the mode of the resin flow at the time of injection in the molded article which has a hollow in an external appearance surface. In addition, FIGS. 6D to 6F are views showing the state of resin flow at the time of injection in a molded product having protrusions on the external surface. The direction of the flow front 15 is parallel to the resin flow direction until the molten resin 14 flowing through the cavity 16 reaches the rib 2. When the molten resin 14 reaches the rib 2, the molten resin 14 is biased toward the rib 2 and the flow front 15 faces toward the rib 2. Thereafter, when the molten resin 14 passes through the rib 2, the flow front 15 faces the mold external surface 17 side. It is considered that the fact that the flow front 15 faces the mold external surface 17 side contributes to the occurrence of unevenness. FIG. 8 is a perspective view for explaining unevenness appearing on the external appearance surface, and shows a plate-shaped resin molded product on which ribs protruding on the non-external appearance surface are formed. 1 is a thin part of the molded product, and 2 is a rib protruding on the non-appearance surface. Reference numeral 71 denotes a gate which is an inlet through which molten resin flows into a cavity for molding a molded product. The unevenness 18 appears on the appearance surface 21 of the molded product, and the position thereof corresponds to the root of the rib 2 on the downstream side of the flow. This position coincides with the position in FIG. 5 and FIG. 6 where the flow front 15 faces the mold external surface 17 side. Therefore, when a repetitive pattern of convex portions is formed by continuously superimposing unit shapes in which two or more spherical crowns having different curvature radii are combined on a non-appearance surface, unevenness of the appearance surface is reduced. Is found.

  FIG. 7 is an example of an embodiment of the present invention, in which a convex portion configured by continuously superimposing unit shapes in which two or more spherical crowns having different curvature radii are combined on a non-appearance surface adjacent to a rib. It is sectional drawing of the mode of the resin flow at the time of injection in the molded article which provided the repeating pattern. The same parts as those in FIG. Since the molten resin 14 flows from various directions into a convex pattern having a convex shape constituted by two or more spherical crowns having different curvature radii, the flow of the resin is disturbed. Since the molten resin 14 is disturbed also in other than the ribs 2 and fine resin disturbance occurs at various angles other than the flow direction of the resin, it occurs only on the appearance surface corresponding to the root of the rib 2. It is considered that the change in color tone is difficult to visually recognize as unevenness. Furthermore, since the repeating pattern of the convex portion is a shape configured by combining a crown shape and an arc shape, all the edge portions are rounded, and the resin can flow more smoothly and uniformly. Thereby, since the resin does not concentrate locally, it is considered that a high effect is exhibited in further reducing unevenness.

  Based on the above experimental results, the present invention provides a non-appearance surface with a repetitive pattern of convex portions, in which unit shapes obtained by combining two or more spherical crowns having different curvature radii that disturb resin flow are continuously superimposed. As a result, it has been found that unevenness caused by protrusions or depressions on the non-appearance surface or protrusions or depressions on the appearance surface can be reduced.

  In FIG. 7, the embodiment of the resin molded product having rib-like protrusions such as ribs protruding from the non-appearance surface has been described. However, the same effect can be obtained for a resin molded product having a dent recessed from the external surface, a resin molded product having a dent on a non-external surface, and a resin molded product having a protrusion on the external surface.

  The following configurations are conceivable for a resin molded product having a dent recessed from the external surface, a resin molded product having a dent on the non-external surface, and a resin molded product having a protrusion on the external surface. For example, the base that connects the molded products is a nail with a prismatic shape, a cylindrical boss, a spherical protrusion, a cylindrical protrusion or depression with an ejector pin with a circular cross section, a prismatic shape with an ejector pin with a square cross section These are protrusions and depressions. In any of these protrusions and depressions, unevenness occurring on the appearance surface is reduced by the present invention. In addition, the present invention reduces unevenness that occurs on the external surface even when the protrusions or depressions on the external surface for guiding the product functions to the user are used. In addition, a unit shape in which two or more spherical crowns having different curvature radii are combined may be arranged over the entire non-viewing surface to form a repeating pattern of convex portions over the entire non-appearing surface. When the convex pattern is formed repeatedly on the entire non-appearance surface, it is more preferable because it is disturbed throughout the entire resin molded product and unevenness is reduced on the entire appearance surface. The term “non-appearance surface” as used herein refers to the back side of the surface that requires the appearance quality to touch the user's eyes. Thus, it does not include regions having functions such as ribs, protrusions, depressions, and contact parts with other parts. In other words, the entire surface of the non-appearance surface includes areas with functions such as ribs, protrusions, depressions, and contact parts with other parts, on the back surface of the surface that requires the appearance quality to touch the user's eyes. Absent.

  FIG. 2 is an enlarged view of a partial cross section 31 of FIG. This cross section 31 is equal to the cross section of a unit shape in which two or more spherical crowns having different radii of curvature are combined. The cross-sectional shape of the unit shape is an arbitrary plane including a perpendicular line 61 that descends from the highest point 60 of the convex portion to the non-appearance surface 102, and the contour line of the convex portion shape is projected onto this projection plane. It shows the shape that is sometimes formed. In FIG. 2, R <b> 1 indicates the radius value of the arc 64 joined to the non-appearance surface 102. R2 indicates the radius of curvature of the arc 65 joined to the arc 64. The relationship between R1 and R2 is represented by the following formula.

R1> R2 (Formula 1)
Further, it is desirable that both the opening angle α1 of the arc 64 and the opening angle α2 of the arc 65 are 180 ° or less. If the opening angle exceeds 180 °, the end of the arc enters the inside, so that the resin flow may stay and deteriorate the appearance shape.

  In the present embodiment, a unit shape in which two spherical crowns are combined is shown, but it is also possible to combine n spherical crowns into a unit shape. In this case, assuming that Rn is a radius value of the arc n joined to the arc n-1, the relationship of R1, R2,... Rn can be expressed by the following expression.

R1>R2>...> Rn (Formula 2)
Further, it is desirable that the opening angle α1 of the arc 64 and the opening angle α2 of the arc 65,.

  In FIG. 1B, reference numeral 104 denotes the thickness between the outer surface 101 and the non-outer surface 102. When the wall thickness 104 is 3 mm or less, the effect of the present invention is best manifested. When the thickness 104 exceeds 3 mm, the influence of the disturbance of the molten resin 14 due to the ribs 2 does not reach the appearance surface 21 and no unevenness is caused in the first place. 105 is the thickness of the rib.

  100 is the height of the convex part of the repeating pattern of convex parts, in which unit shapes obtained by combining two or more spherical crowns having different curvature radii are continuously superimposed. The height of the convex portion is a distance between the top portion of the convex portion and the reference surface of the non-appearance surface. The top part of a convex part shows the highest point of the repeating pattern of a convex part. The reference surface of the non-appearance surface is a plane connecting points where the repetitive pattern of the convex portions intersects with the non-appearance surface, and includes a plane including a surface where the repetitive pattern of the convex portions is not formed. The convex part height is a distance between the intersection of the perpendicular line and the reference surface and the top part of the convex part when a perpendicular is drawn from the top of the convex part to the reference surface of the non-appearance surface. If the height of the convex portion is 0.01 mm or more and 1 mm or less, the effect of the present invention is best exhibited. When the height of the convex portion is less than 0.01 mm, the molten resin cannot be disturbed so much by the repeated pattern of the convex portion, and the effect of reducing unevenness is less than that when the height is 0.01 mm or more. If the thickness exceeds 1 mm, the molten resin 14 is disturbed by the repeating pattern of the convex portions, but unevenness occurs on the appearance corresponding to the repeating pattern of the convex portions, and the appearance quality is deteriorated. There is.

  When the appearance surface 101 is black or dark color, the effect of the present invention is best exhibited. In addition, when the surface of the external surface is a glossy mirror surface or a textured surface, the effects of the present invention are best exhibited.

  An example of a resin molded product that exhibits the effects of the present invention is a document cover used in a printer or the like. FIG. 10 is a perspective view of a printer provided with a document reading device. Reference numeral 19 denotes a printer. A casing 20 such as a document cover 23 is formed of a black resin, and the surface thereof is a mirror surface. FIG. 11 is a perspective view showing a state in which the document cover 23 is opened. A repetitive pattern of convex portions is formed by continuously superimposing unit shapes combining two or more spherical crowns having different curvature radii on a part or the entire surface of the non-appearance surface 22 of the document cover shown in FIG. . As a result, the occurrence of unevenness in the appearance can be suppressed, and the appearance quality is significantly improved.

  Next, the manufacturing method of the resin molded product of this invention is demonstrated. A resin molded product is manufactured by transferring the shape of the mold surface by pouring resin into the mold.

  First, a shape for transferring a repetitive pattern of convex portions is formed on a mold by continuously superimposing unit shapes obtained by combining two or more spherical crowns having different curvature radii. FIG. 3 is a diagram showing a processing method for forming a shape for transferring a repeated pattern of convex portions on a mold. In FIG. 3, reference numeral 200 denotes a mold for transferring the non-appearance surface. The mold 200 is formed with a recess 201 for forming a rib by transferring (the rib is formed by transferring the recess). First, two types of ball end mills having different diameters are scanned in the first direction of the mold surface. First, the first ball end mill 300 having a tool surface made of a spherical surface having a first diameter is scanned to form a recess. Thereafter, a second ball end mill having a tool surface made of a spherical surface having a diameter smaller than the first diameter is scanned to further form a groove inside the groove. At this time, the second ball end mill has a spherical sphere center and a second ball end mill spherical sphere center that is parallel to the normal direction of the mold surface. The ball end mill is scanned. Thereafter, the scanning direction is changed to a second direction different from the first direction, and the first ball end mill 300 having a tool surface made of a spherical surface having a first diameter is scanned to form a recess. Thereafter, a second ball end mill having a tool surface made of a spherical surface having a diameter smaller than the first diameter is scanned to further form a groove inside the groove. At this time, the second ball end mill is scanned so that the line connecting the center of the spherical surface of the first ball end mill and the center of the spherical surface of the second ball end mill is parallel to the normal direction of the mold surface. Let As for the scanning direction, either the first direction or the second direction is preferably scanned in a direction parallel to the depression 201 for forming the rib, and the other direction is the depression 201 for forming the rib. However, the present invention is not limited to this. Further, the ball end mill may be further scanned in a third direction different from the first direction and the second direction. Thereby, the repeating pattern of a recessed part which overlap | superposed the unit shape which combined two or more spherical crowns from which a curvature radius differs on a metal mold | die is formed. The resin is poured into this mold. As a result, as shown in FIG. 3B, a unit shape in which an external surface 101 having a mirror surface or a textured surface, a rib 2 protruding from the non-external surface 102, and two or more spherical crowns having different curvature radii is combined. Then, a repeated pattern of convex portions, which are continuously overlapped, is formed. In addition, when this processing method is used, as shown in FIG. 3C, even if the mold surface to be processed is an inclined surface, by using two or more types of ball end mills having different diameters, Patterns can be formed repeatedly without tilting the mold and leveling the surface. Thus, even if the surface of the mold is inclined, it can be processed by the two or more types of ball end mills, so there is no need to create a dedicated jig and level the mold surface. FIG. 4 shows an example in which a V-groove shape having two sides is machined on the mold slope. In the case of the V-groove shape, the shape cannot be processed with a rotary tool such as an end mill while the processing surface is inclined, and a special setup jig or machine is required. In this way, the repeating pattern of convex parts, in which unit shapes composed of two or more spherical crowns with different curvature radii are continuously overlapped, has high workability and is effective in preventing unevenness of resin molded products. It can be seen that the shape has both workability and unevenness prevention.

  The present invention is not limited by the mold temperature. The same effect can be obtained even when the mold temperature is about the glass transition temperature of the resin. The same effect can be obtained even when the mold temperature is sufficiently low. The present invention is not limited by the type of resin. PC / ABS, PS, HIPS, etc. have the same effect.

  Next, examples will be described.

  As a specific example in which the present invention is implemented, an example in which the present invention is applied to a simple shape of a document cover shape that is a part of a housing of a composite printer including a document reading device will be described. In the embodiment, an example in which the present invention is applied to the non-appearance surface 22 of the simple model of the document cover shown in FIG.

Example 1
A simple shape 20 of the document cover is formed of black resin, and the surface thereof is a mirror surface. The wall thickness was 2.3 mm, and the rib 2 thickness was 1.2 mm. The color was black and the appearance surface 21 was a glossy mirror surface. Molding was performed at a mold temperature of 50 ° C., an injection time of 2.5 s, and a resin temperature of 220 ° C. ABS was used as the resin material.

  The shape of the unit shape part constituting the repetitive pattern of the convex part formed on the non-appearance surface 22 is a convex part combining two or more spherical crowns having different curvature radii, and the non-appearance surface of the molded product and the apex part of the convex shape The distance was set to 0.1 mm. In addition, the two crown-shaped crowns having different radii of curvature formed on the non-appearance surface 22 were formed with projections having R1 of 3 mm and R2 of 0.5 mm on the entire non-appearance surface.

(Example 2)
Molding was performed under the same conditions as in Example 1 except that the shape of the unit shape part constituting the repeated pattern of convex parts was changed to three spherical crowns having different curvature radii.

(Comparative Example 1)
Table 1 shows the results of unevenness evaluation and workability evaluation of Example 1, Example 2 and Comparative Example 1, which were molded by the same method as Example 1, except that the convex pattern was not formed on the non-appearance surface 22. Shown in In the table, the evaluation item ○ indicates unevenness improvement and × indicates unevenness. Δ indicates that there is no problem because it is not recognized as unevenness, but a slight change is recognized on the surface. In the evaluation of the workability items in the table, ○ indicates that processing is possible without special setup on both the plane and the slope, and × indicates that processing without special setup is possible on either the plane or the slope.

(Example 3)
Molding was performed under the same conditions as in Example 1 except that the thickness of the simple shape 20 of the document cover was changed to 2.3 mm.

Example 4
Molding was performed under the same conditions as in Example 1 except that the thickness of the simple shape 20 of the document cover was changed to 3.0 mm.

(Example 5)
Molding was performed under the same conditions as in Example 1 except that the thickness of the simple shape 20 of the document cover was 3.1 mm.

(Example 6)
Molding was performed under the same conditions as in Example 1 except that the thickness of the simple shape 20 of the document cover was changed to 0.5 mm.

(Comparative Example 2)
Molding was performed in the same manner as in Example 3 except that the convex pattern was not formed on the non-appearance surface 22.

(Comparative Example 3)
Molding was performed in the same manner as in Example 4 except that the convex pattern was not formed on the non-appearance surface 22.

(Comparative Example 4)
Molding was performed in the same manner as in Example 5 except that the convex pattern was not formed on the non-appearance surface 22.

(Comparative Example 5)
Molding was performed in the same manner as in Example 6 except that the convex pattern was not formed on the non-appearance surface 22.

  The results of Example 3, Example 4, Example 5, Example 6, Comparative Example 2, Comparative Example 3, Comparative Example 4, and Comparative Example 5 are shown in Table 2.

(Example 7)
The molding was performed under the same conditions as in Example 1 except that the height of two or more spherical crown-shaped convex portions having different curvature radii formed on the non-appearance surface 22 was set to 1 mm.

(Example 8)
The molding was performed under the same conditions as in Example 1 except that the height of two or more spherical crown-shaped convex portions formed on the non-appearance surface 22 and having different curvature radii was 0.01 mm.

Example 9
The molding was performed under the same conditions as in Example 1 except that the height of the two or more spherical crown-shaped convex portions having different curvature radii formed on the non-appearance surface 22 was 1.1 mm.

(Example 10)
Molding was performed under the same conditions as in Example 1 except that the height of the two or more spherical crown-shaped convex portions formed on the non-appearance surface 22 and having different curvature radii was 0.009 mm.

  The results of Example 7, Example 8, Example 9, and Example 10 are shown in Table 3.

(Example 10)
The opening angle α1 of two or more spherical crown-shaped first crowns formed on the non-appearance surface 22 and having different radii of curvature was set to 22.9 °, and the opening angle α2 of the second crown was set to 39.6 °. As a result of molding under the same conditions as in Example 1, the effect of improving unevenness was observed.

  As described above, the occurrence of unevenness can be improved by the repeated shape of two or more crown-shaped convex portions having different curvature radii. Compared with other shapes, the effect of improving unevenness and the mold surface can be improved. It was possible to achieve both workability.

  The present invention can be widely applied to resin molded products that require a highly functional surface that does not allow a change in color tone, such as resin molded products that require a dark colored design surface with resin casings of various apparatuses.

DESCRIPTION OF SYMBOLS 1 Molded product thin part 2 Rib 3 Convex shape comprised by two spherical crowns with different curvature radii provided on non-external surface 14 Molten resin 15 Flow front 16 Cavity 17 Mold external surface 18 Uneven surface 31 Non-external surface Convex single shape composed of two spherical crowns with different radii of curvature 21 Appearance surface of molded product

Claims (5)

It has an external surface and a non-external surface, and a thickness between the external surface and the non-external surface is 3 mm or less, a protrusion or a depression on the external surface, and a reference surface on the non-external surface In the resin molded product in which at least one of protrusions or depressions is formed, a convex shape is formed by continuously superimposing unit shapes combining two or more spherical crowns having different curvature radii on the non-appearance surface. A resin molded product in which a repeated pattern of the part is further formed.   The resin molded product according to claim 1, wherein a height of the convex portion from a reference surface of the non-appearance surface is 0.01 mm or more and 1 mm or less.   The resin molded product according to claim 1 or 2, wherein an opening angle of two or more spherical crowns having different curvature radii is 180 ° or less. A method for producing a resin molded product for producing a resin molded product by transferring the shape of the mold surface by pouring resin into a mold,
A groove is formed by scanning a first ball end mill having a tool surface composed of a spherical surface having a first diameter on the mold surface having a recess for forming a rib by transferring, and then forming the groove. Scanning a second ball end mill having a tool surface comprising a spherical surface having a diameter smaller than the diameter to form a groove further inside the groove;
The step of forming the groove includes the second ball end mill so that a line connecting the center of the spherical surface of the first ball end mill and the center of the spherical surface of the second ball end mill is parallel to the normal direction of the mold surface. By scanning the ball end mill, a concave portion in which a repeating pattern of convex portions is formed by continuously superimposing unit shapes in which two or more spherical crowns having different curvature radii are combined by transfer is formed. A method for producing a resin molded product.   A printer comprising a document cover manufactured by the method for manufacturing a resin molded product according to claim 4.

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