JPS61121914A - Two-color molding - Google Patents

Abstract

PURPOSE:To obtain two-color resin molded product, distinct in the section of boundary and good in appearance, by a method wherein the section of pattern is molded by primary molding side and, subsequently, the section of main body is molded by secondary molding utilizing the cavity of the mold of secondary molding side, which is shallower than the depth of the section of pattern. CONSTITUTION:In case the pattern section 1 and the main body section 2 are molded integrally by two-color molding method, the cavity 3 of primary molding side mold is met with a core side mold 4 at first to make the primary molding of the pattern section 1 at first. Subsequently, the secondary molding side mold cavity 6, set so as to be shallower than the height H of the primary molded product by a minute amount delta, is used and the molds are clamped until the gap delta of the section 7 becomes zero whereby the secondary injection molding of the part 2 is effected under a condition that the part 1 is crushed. According to this method, the two-color resin molded product, distinct in the boundary between the pattern section and the main body section and having good appearance, may be manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for manufacturing a resin molded product in which characters, patterns, etc. are integrally molded by a two-color molding method.

Conventional Structure and Problems Conventionally, when making the pattern part 1 and the main body part 2 as an integral molded product as shown in FIG. The mold cavity is replaced with a secondary mold cavity for molding the main body, and the main body part is secondary molded to make an integral molded product. The depth of the secondary cavity was set to be the same during molding.

This method results in a molded product with poor external finish at the boundary between the pattern and the main body.

In other words, as shown in Figure 2, resin is first injected into the gap between the mold cavity 3 on the primary molding side and the core mold to mold the pattern part 1. The tip part A of H is the pattern part of the integrally molded product, but as shown in Fig. 3, which is an enlarged view of this part, the corner 6.5' of the pattern is due to the slight radius during mold processing and the injection molding process. The corners become sagging due to the influence of air, gas, etc.

Next, as shown in FIG. 3, the fire forming side mold cavity is replaced with a secondary molding side mold cavity 6, and the core side mold and the next side molded product 1 are connected to the secondary molding side mold cavity. The main body part 2 is injection molded in the gap between the mold cavity 6 and an integrally molded product. As shown in the figure,
When the resin 2 of the main body part flows into the R part 3 vane at the corners 5 and 5' of the pattern part, grooves may protrude at the boundary part due to the influence of air and gas.

For this reason, as shown in FIG. 5, the boundary between the pattern portion 1 and the main body portion 2 is not a straight line, making the pattern look thick or thin, resulting in an unsightly appearance.

Conventionally, as a countermeasure to this problem, efforts have been made to reduce the radius of the corner of the pattern part mold by increasing the injection pressure on the next molding side, but this is not perfect. The disadvantage is that the phenomenon shown in Figure 5 inevitably remains without cutting.

OBJECTS OF THE INVENTION The present invention provides a method for producing a two-color molded product having a good-looking pattern by sharpening the boundary portions of patterns and the like produced by the two-color molding method.

Structure of the Invention The present invention involves: - forming a pattern on the secondary molding side; This is a configuration in which the main body part is secondary-molded with the pattern part crushed, and the boundary between the pattern part and the main body part becomes clear and a molded product with good appearance can be obtained.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention is shown in FIGS. 7 to 11 and will be described.

When integrally molding the pattern part 1 and the main body part 2 as shown in FIG. 7 by the two-color molding method, first, the core side mold 4 and the primary mold side mold cavity are aligned to primary mold the pattern part 1. .

When the pattern portion at this time (part A in Fig. 8) is enlarged, it becomes as shown in Fig. 9.

That is, the corners 5.5 forming the pattern of the next molded product 1.
' is 0.02m-0, a slight difference of about 2mb/'' -R is attached.

Next, the fire forming side mold cavity 3 is removed and replaced with the secondary forming side mold cavity 6.

The depth of this secondary molding side mold cavity 6 is set to be shallower than the height H of the secondary molded product by a minute amount δ.

Page 5 In other words, when the secondary molding side mold cavity 6 closes, at the point when the tip of the pattern part 1 comes into contact with the back of the secondary molding side mold cavity 6, a minute amount of contact with the core side mold occurs. There is a gap of δ.

Next, after clamping the mold until the clearance δ at the part 7 becomes 0, the main body part 2 is inserted into the clearance between the pattern part 1, the far side mold 4, and the secondary mold cavity 6. An integral molded product is made by injection molding.

At this time, when part C forming the pattern is enlarged, it becomes as shown in Fig. 11.

In other words, the corner portions 8, 8' that make up the pattern are crushed by the secondary molding die 6, the minute radius of this corner portion disappears, and the pattern is deformed into a shape with acute corners, forming the main body portion there. The resin is injection molded.0 Note that if the pressing amount δ at this time is set to a large value, the pattern thickness W will become thicker, and if the reverse pressing amount δ is set to a small value, the pattern thickness W will be made thinner. This is possible.

Effects of the Invention 6 bases/ As described above, according to the present invention, even if a small radius remains in the pattern part of a conventional molded product, by crushing the tip part, the border between the pattern part and the main body part is clear and has a good appearance. ◇ Furthermore, by pressing the pattern part of the next molded product, it is possible to prevent the pattern part from deforming due to the resin pressure during secondary molding, and the thickness of the pattern can be changed by increasing or decreasing the amount of compression. This will allow you to adjust it.

[Brief explanation of the drawing]

Figure 1 is a plan view of a molded product in which the pattern and main body are integrally molded, Figure 2 is a partial cross-sectional view of the mold used to primary mold the pattern, and Figure 3 shows the pattern shown in Figure 2. FIG. 4 is a partial sectional view of the mold for secondary molding the main body portion; FIG. 5 is an enlarged sectional view of the pattern forming portion of FIG. 4;
The figure is a plan view of a molded product completed by the conventional method.
The figure is a plan view of a molded product in which the pattern part and the main body part are integrally molded, and Figure 8 is a cross-sectional view of the mold when the pattern part is primarily formed.
Figure 9 is an enlarged cross-sectional view of the part constituting the pattern in Figure 8, and Figure 1o is a cross-section of the mold just before the mold cavity is replaced with the mold cavity on the secondary molding side and the main body part is molded. FIG. 11 is an enlarged sectional view of a portion constituting the pattern of the molded product molded according to FIG. 10. 3... Mold cavity, 4... Core side mold, 5... Corner, 6... Mold cavity. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 6
Figure 7 Figure 8 Figure '9

Claims (1)

[Claims] The pattern part was molded on the primary molding side, and then the pattern part was crushed using the mold cavity on the secondary molding side, which was set shallower than the depth of the pattern part in the mold cavity on the primary molding side. A two-color molding method in which the main body part is secondary molded in the state.