JPS6387215A - Preparation of decorative molding - Google Patents

Abstract

PURPOSE:To produce a uniform spread and flow of a molten resin, by allowing a relatively large resistance to act on the flow in a cavity gap corresponding to a place where a distance to the circumferencial part is short when a molten resin injected at a roughly central position of the rear face side spreads and flows in a circular shape along the rear face. CONSTITUTION:Resistances to flow of a molten resin are made different, in a cavity gap corresponding to positions 1a, 1a... where the distance l1 from the resin injection position of an in-flowing gate 12 to the circumferencial part of a main body of a molding 1 is short, and in a cavity gap corresponding to position 1b where the distance l1 is long, from each other and the difference in resistance to flow is made in such a way that it is larger at the positions 1a, 1a... where the distance l1 is shorter than at the position 1b where the distance l1 is long. The molten resin 2 covering over the rear face of the main body of the molding flows into a cavity gap 11d of the front face side almost simultaneously from the whole circumferencial side through a cavity gap 11c of the circumferencial side face, and gaps which may otherwise generate by catching air bubbles do not occur at the frame part of the bottom side which is visible from the outer surface.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to the production of a molded product using an apparatus in which a frame is integrally formed on a molded product body having a plate-like non-circular peripheral shape by injection molding of molten resin. It is about the method.

BACKGROUND ART In general, decorative molded products of this type include an opera window W and a finisher F installed on a vehicle as shown in FIG.

Of these, taking Opera Window W as an example, it is the first
Glass or ? , 4 M.A.

A molded product body 1 is formed using a synthetic resin such as PC to have a transparent plate shape and a non-circular peripheral shape, and the stiffness is formed by an injection molding die consisting of a core mold 10a and a cavity mold 10b as shown in FIG. The frame portion is integrally molded by injecting molten resin 2 into the cavity space 11 of 10. At this time, if the molten resin 2 is injected from the direction orthogonal to the approximately central position on the back side of the molded product main body 1, the injection pressure of the molten resin 2 can be applied to a relatively wide area, thereby moving the molded product main body 1 into the cavity space. It is conceivable that the frame can be formed without shifting or lifting within the frame 11.

Problems to be Solved by the Invention However, if the molten resin 2 is only injected from the center position of the side path on the back surface of the molded product body 1, the molten resin 2 will gradually spread in a substantially circular shape along the back surface 8. When working, as shown in Fig. 12, the molten resin 2 reaches the edges closer to the center position earlier than the edges farther away, so the cavities on the side end surfaces are The molten resin 2 fills from the gap to the cavity space on the front side, and furthermore, the molten resin 2 quickly turns around to the edges where it has not yet flowed, causing a situation where it flows back toward the back side as shown in FIG.

In this case, as shown in FIGS. 14 to 16, the molded product body 1
Air bubbles are drawn into the back side of the frame 2' to form a gap 3, which may remain visible from the front side as shown in FIG. 17.

Means for Solving the Problems In the method for manufacturing a decorative molded product according to the present invention, the peripheral edge of the molded product body is relatively The flow resistance to the molten resin is made larger than that in the cavity gap corresponding to the part where the distance to the molded article is long, so that the molten resin spreads and flows substantially uniformly over the entire back side of the molded product body.

Function: In this method for manufacturing decorative molded products, when the molten resin injected from approximately the center on the back side of the molded product body spreads in a circular shape along the back side and flows, a cavity corresponding to the area where the distance to the peripheral edge is short is created. By applying a relatively large flow resistance to the molten resin in the gap, the molten resin flows almost evenly toward the back side in synchronization with the areas where the distance to the periphery is long, so that it covers almost the entire back side. After that, the air bubbles can be moved six times so as to flow toward the front side, so that no voids due to air bubbles remain at least on the back side.

An example will be described below with reference to FIGS. 1 to 8.

This embodiment is for manufacturing decorative molded products for vehicles such as the opera window W and finisher F shown in FIG. , is molded from a synthetic resin such as PC into a transparent plate-like substantially triangular non-circular outline. For this molded product body 1, a frame part extending from the entire back side to the plate surface near the edge on the front side is formed around the entire circumference using a synthetic resin colored in a different color using the injection mold 10 shown in Fig. 1. A relatively large cavity space 11 in which the molded product main body 1 can be inserted is provided between the core mold 10a and the cavity mold 10b. In the mold 10, a molded product main body 1 is placed inside a cavity mold 10b with its front side facing each other, and the molten resin can be injected from a direction perpendicular to the rear surface of the molded product main body 1 at an approximately central position. A gate 12 is provided in the core mold 10a.

In this mold 10, as shown in FIG. 2, the distance from the resin injection position of the inflow gate 12 to the peripheral edge of the molded product body 1! 1
The flow resistance to the molten resin is made different between the cavity gaps corresponding to the points 1a, la, etc. where j2 t is short and the cavity gaps corresponding to the points 1b where the distance 1eft i2 is long, and the resistance difference is the distance 1, part 1a where is short
, la .

This difference is due to the short distance Il!, as shown in Figure 3 a and b. t It
The cavity gap 11a at the location corresponding to l is a long distance violet f,
Between the cavities at the location corresponding to t! It can be attached by making the width smaller than jHxb (1+<12). In the mold 10, when the molten resin 2 is injected from the approximate center of the molded product body 1 to the back surface, the cavity gap 11b with the large width t2 causes the molten resin 2 to flow relatively quickly, whereas the small width t, By allowing the molten resin 2 to flow slowly in the cavity gap 11a, it becomes possible to spread and flow the molten resin 2 in a generally synchronous manner as shown in FIG.

Moreover, the above-mentioned resistance difference is as shown in FIG.
A plurality of protrusions 11a', lla', etc. are formed on the inner surface of the cavity of a& in a portion corresponding to a short distance from the resin injection position of the inflow gate 12 to the peripheral edge of the molded product body 1, and the distance is long. This can also be achieved by forming the corresponding portions into smooth surfaces. In the mold 10, when the molten resin 2 is injected from the approximate center of the molded product body 1 to the back surface, the protrusions 11a', lla', etc. shown in FIG. 6a are formed.
The flow rate of the molten resin 2 is suppressed on the side where . is formed, and the flow rate is relatively faster on the smooth cavity surface 11b' side shown in FIG. This allows the molten resin 2 to spread and flow over the entire back surface, as shown in FIG.

Therefore, in the manufacturing process of the decorative molded product shown in FIGS. 3 and 6, the molten resin 2 covering the back surface of the molded product body passes from the entire periphery, almost simultaneously through the cavity interval 11C on the circumferential side, and then passes between the cavities 11C on the front side. ! 111d, and no voids due to entrainment of air bubbles are created at least in the frame portion on the bottom side that is visible from the outer surface.

Note that an identification mark can be previously formed on the back side of the molded product main body 1 by printing, pasting a sticker, or the like. Also,
Although the above-mentioned embodiments have been explained based on normal injection molding, reaction injection molding can also be applied.

Effects of the Invention As described above, according to the method for manufacturing a decorative molded product according to the present invention, a frame portion of a predetermined thickness is formed into a molded product body without leaving any voids on the back side that can be seen from at least the outer surface of the frame portion. Can be precisely formed around the entire circumference of the

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing the manufacturing process of a decorative molded article according to the present invention, Fig. 2 is an explanatory diagram showing the range of changing the flow resistance to molten resin in the same manufacturing process, and Fig. 3a is A of Fig. 2. - An explanatory diagram showing an enlarged flow state of the molten resin in the A-line cross section, 3rd
The figure is an explanatory diagram showing an enlarged flow state of the molten resin in the cross section taken along the line B-B in Figure 2, and Figure 4 is an explanatory diagram schematically showing the flow state of the molten resin due to the flow resistance shown in Figure 2. FIG. 5 is an explanatory diagram when the flow resistance is changed by another means, FIG. Figure 7 is an explanatory diagram showing an enlarged view of the resin flow force state in a portion where the flow resistance is relatively reduced using the method shown in Figure 5. FIG. 8 is an explanatory diagram showing the flow state of the molten resin by the means shown in FIG. 5. FIG. 9 is a partial perspective view of a vehicle body showing what is installed on the vehicle as a decorative molded product. FIG. 10 1 is a perspective view showing the main body of an opera window molded product exemplified as a molded product of the same type, FIG. 11 is an explanatory diagram showing the manufacturing process of a decorative molded product exemplified as a background technology, and FIG. Fig. 13 is an explanatory drawing showing the flow state of the molten resin in the same process in an enlarged manner, Figs. It is a top view which shows the problem of the decorative molded product manufactured by the same process. 1: Molded product body, 2: Molten resin forming the frame, lO:
Injection mold, 11: Cavity space, 1
1a: Cavity gap with a short distance from the molten resin injection position to the edge of the molded product body, 11b: Cavity gap with a long distance from the molten resin injection position to the edge of the molded product body, 12: Inflow of molten resin Gate, 1. ．． 1. Width of cavity gap, f, f: Distance from injection position of molten resin to edge of molded product, 1 lb', 1 lb'...
: Convex stripe. Patent applicant: Hashimoto Forming Industry Co., Ltd. Patent attorney Kazu Eiji Takeshita Figure 1 Figure 3 Figure 2 Figure 4 Figure 6 Figure 5 Figure 6O Figure 10 Figure 13 Figure 17

Claims (3)

[Claims] (1) A transparent plate-shaped molded product body with a non-circular peripheral edge shape is placed in the cavity space, and molten resin is injected from approximately the center of the back side, so that the entire back side and near the front side periphery are formed. When injection molding a frame that spans the plate surface, the cavity gap corresponds to the area where the distance from the molten resin injection position to the periphery of the molded product body is short, and the distance to the periphery is relatively long. A method for manufacturing a decorative molded article, characterized in that the flow resistance to the molten resin is made larger than that of the cavity gap, and the molten resin spreads and flows substantially uniformly over the entire back surface of the molded article body. (2) The cavity gap corresponding to the short distance is made smaller than the cavity gap corresponding to the long distance so that a large flow resistance to the molten resin acts. A method for producing decorative molded products. (3) Manufacture of a decorative molded article according to claim 1, in which a plurality of protrusions are formed on the inner surface of the cavity corresponding to the short distance points so that flow resistance to the molten resin is large. Method.