JPH0890585A - Blow resin molded product and mold for producing the same - Google Patents

Abstract

PURPOSE: To obtain a blow resin molded product having such a structure that the side wall thick-walled part of a hollow part is provided and the hollow part is still more reinforced by arranging piercing recessed parts to the thick- walled part and capable of being smoothly demolded without generating deformation and damage by gas injection molding. CONSTITUTION: Side wall thick-walled regions 5 and side wall thin-walled regions 6 are alternately formed in the hollow part 10 of a blow resin molded product in an unopposed state so as to hold the longitudinal center axis of the hollow part therebetween and piercing recessed parts 4 are provided to the thick-walled regions 5. At the time of gas injection molding, the projections provided to the cavity surface of a mold corresponding to the piercing recessed parts 4 become resistance against the flow of a thermoplastic resin and, since gas is injected in this state, thick-walled regions 5 are formed around the projections. At the same time, thin-walled regions 6 relatively thinner than the thick-walled regions are formed to both ends of the thick-walled regions 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hollow resin molded product produced by a gas injection injection molding method and a mold for producing the hollow resin molded product.

[0002]

2. Description of the Related Art Gas injection injection molding reduces the weight of molded products,
It is widely used because it contributes to the prevention of surface defects such as sink marks. In this molding method, after injecting the molten resin into the mold cavity, injecting pressurized gas in the uncured state,
The resin is pressed against the cavity surface from the inside while forming a gas passage that becomes a hollow portion in the molten resin inside the thick wall such as a boss and a rib.

On the other hand, the hollow portion formed in the molded product may be deformed or damaged by the load, and as a countermeasure against this, there is a proposal to dispose a plurality of columns inside the hollow portion to reinforce the hollow portion. Kaihei No. 5-228965).

This is a gas injection injection using a mold in which a plurality of protrusions are provided on the cavity surface of a movable mold and the tips are slightly separated from each other so that they do not contact the opposing cavity surface. It is to mold.

[0005]

However, in the above proposal, the tip of the protrusion and the cavity surface are separated from each other,
Therefore, not only is it difficult for the molded product to be released from the mold due to the injection resin pressure or injection gas pressure, but at the same time, there is a problem with the mold such that the projection bends, and the molded product side is also deformed and damaged. Sometimes.

The present invention provides a hollow resin molded product which has a structure in which the hollow part is further reinforced by improving the drawbacks of such a mold and which can be smoothly released from the mold without being deformed or damaged. At the same time, the purpose is to provide a mold for that purpose.

[0007]

As a result of intensive studies, the present inventor has found that it is effective to bring the protrusions arranged on the mold cavity surface into contact with the opposing cavity surface or the protrusion surface. The inventors have found that it is more effective to arrange the protrusions in a specific arrangement, and that a hollow resin molded product having an excellent reinforcing effect can be obtained by using these molds, and the present invention has been completed.

That is, the present invention is (1) a hollow resin molded product obtained by gas injection injection molding, which has a hollow side wall thick-walled area and a through-recessed portion is arranged in the thick-walled area. A hollow resin molded product characterized by being provided, (2) a hollow resin molded product obtained by gas injection molding, wherein the hollow part side wall is thick in a non-face-to-face manner with the central axis in the longitudinal direction of the hollow part sandwiched. A hollow resin molded product having a region and a through recess formed in the thick region, and (3) a hollow resin molded product including a fixed mold and a movable mold for gas injection injection molding. A hollow mold according to (1) above, wherein a plurality of protrusions are provided on the cavity surface of the fixed mold and / or the movable mold so as to be in contact with the facing cavity surface or the protrusion surface. From molds for molding production, (4) fixed mold and movable mold for gas injection injection molding A hollow resin molded article mold that,
The fixed mold and / or the movable mold are arranged such that a plurality of projections are in contact with the opposing cavity surfaces and are arranged in a non-face-to-face manner with the central axis in the longitudinal direction of the cavity sandwiched therebetween. 2) A mold for producing a hollow resin molded article as described above.

In the hollow resin molded product of the present invention, the structure of the hollow portion is important, and other matters are not particularly limited.

The hollow portion of the hollow resin molded product of the present invention has a thick-walled region on at least one side wall of the hollow portion, and the thick-walled region extends from one surface of the hollow resin molded product to another. A recess is provided that penetrates the surface. In addition to forming the thick portion, the rigidity of the hollow portion against the load applied to the hollow portion is further improved.

When the thick-walled portion region is provided only on one side of the central axis in the longitudinal direction of the hollow portion and extremely close to the side end portion, it is opposed to the thick-walled portion side due to the load applied to the molded product. Stress may concentrate on the thin-walled side and the hollow may be deformed or bent. Therefore, in such a case, it is preferable to form the concave portion close to the central axis so as to project the thick-walled region toward the opposite side (FIG. 12). Then, in another aspect of the present invention, the thick-walled regions in which the recesses are arranged are alternately formed in a non-face-to-face manner with the central axis in the longitudinal direction of the hollow portion sandwiched therebetween. In this case, the hollow portion is formed in a meandering shape, and the product rigidity is further improved with respect to the load applied to the molded product by the help of the recess serving as the pressure resistant reinforcing portion.

In the hollow resin molded product of the present invention, as described above, the hollow portion has a penetrating recessed portion in the thick walled portion. However, in order to improve the appearance and feel of the molded product, the recessed portion may be capped if necessary. Closed with leather wrapping, fitting of exterior moldings, polyethylene, polyvinyl chloride,
It can be further molded and covered with a soft resin such as a thermoplastic elastomer. At the time of this molding, since the concave portion supports the injection pressure, it is possible to prevent the hollow portion from being deformed, swollen, or collapsed. The diameter of the recess is not particularly limited and can be set as appropriate, but is preferably 2 to 6 mm.

Next, a mold for manufacturing the hollow resin molded product having the above hollow structure will be described.

The mold of the present invention comprises a fixed mold and a movable mold, one or both of which is provided with a projection, and is constructed so as to be in contact with the cavity surface facing each cavity surface or the tip end surface of the projection. It For example, it is configured so as to abut against the facing cavity surface or enter the inside thereof. Further, the tip surfaces of the protrusions may be brought into contact with each other.
By disposing the protrusions in this way, it is possible to prevent deformation due to resin injection pressure or gas injection pressure. Therefore, in other words, the hollow resin molded product of the present invention has a through recess corresponding to such a shape of the protrusion, but by having such a shape, the mold release after molding can be performed smoothly. . Further, in another aspect of the present invention, the protrusions are alternately arranged in a non-face-to-face manner with the central axis in the cavity longitudinal direction interposed therebetween.

The shape of the protrusion is not particularly limited, and may be a conical shape with a thin tip, a pyramid shape, a cylindrical shape, or the like. The diameter is also not particularly limited, but is preferably 2 to 6 mm. The larger the number and the diameter of the protrusions are, the more it is possible to withstand the injection pressure at the time of two-color molding of the exterior soft resin, and also the effect of preventing the resin from idling.

In the mold of the present invention, when the protrusion is provided on only one side of the center axis in the longitudinal direction of the cavity, the protrusion should be arranged near the center axis as described for the corresponding hollow resin molded product. preferable. In the mold of the present invention, it is important to provide the projection on the cavity surface as described above, and there are no particular restrictions on other matters. For example, the injection gas can be a nozzle injection, a runner injection, or a cavity injection.

The hollow resin molded product of the present invention can be manufactured by a gas injection injection molding method using such a mold. Also in this molding method, there is no particular limitation other than the mold used.

[0018]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an example of a hollow resin molded product of the present invention,
It is a whole perspective view of an assist grip. In FIG.
Reference numeral 1 denotes an assist grip, which is provided with a grip portion 2 at the central portion and support portions 3 at both ends. A gate 2b of the runner 2a is set on the center end surface of the grip portion 2. Further, the grip portion 2 is provided with a plurality of through recesses 4, but the through recesses 4 are alternately arranged at equal intervals with respect to the center in the longitudinal direction of the assist grip. FIG. 2 is a cross-sectional view taken along the line 1A in FIG. 1, in which the thick side wall regions 5 and the thin side wall regions 6 are alternately formed in the hollow portion 10 in a non-face-to-face manner with the central axis of the hollow portion in the longitudinal direction. There is. The through recess 4 is located in the thick area 5. The protrusions 7 provided on the surface of the mold cavity, which will be described later, corresponding to the through recesses at the time of gas injection injection molding become a resistance against the flow of the thermoplastic resin such as polyolefin, ABS, polystyrene and polyvinyl chloride, and This is because a thick portion region is formed around the protrusion 7 because gas is injected in that state. At the same time, thin-walled regions which are relatively thinner than the thick-walled regions are formed at both ends of the thick-walled region.

FIG. 3 is a sectional view taken along line B of FIG. FIG. 3 shows that the recess 4 is in a penetrating state.

FIG. 4 shows the recess 4 of the hollow resin molded product of the present invention.
FIG. 5 is a vertical cross-sectional view of a mold at a position corresponding to. The protrusion 7 for forming the concave portion 4 on the molded product from the side of the movable mold 8 is in contact with (7a) the cavity surface of the fixed mold 9 which is opposed. 5 shows another embodiment of the mold of the present invention,
It shows a structure in which the tip end 7 b of the projection 7 enters from the cavity surface of the fixed mold 9 into the inside thereof. Such a structure
The proof stress is further improved against the injection pressure, and the protrusions are less likely to be deformed. FIG. 6 shows another embodiment in which the protrusions 6 are provided on both the movable mold and the fixed mold, and the tip surfaces 7c of them are abuttable in the cavity. FIG. 7 is a modification of FIG. 6 in which projections and depressions are provided on the tip surface to provide positioning and positional deviation prevention effects.

Although FIG. 8 shows a modified example corresponding to FIG. 3, it is possible to selectively provide a thick portion in the thick portion region of the hollow portion of the molded product by forming the projection as a step. Also,
It is also possible to arrange a plurality of protrusions 6 on the opposite cavity surface side to form a molded product as shown in FIG.

10 and 11 show a hollow portion structure manufactured by using a mold in which the protrusions are arranged on only one side surface.

In such a case, if the protrusion is in an extremely hard position, when stress is applied to both end portions 3 of the manufactured molded product, stress is concentrated on the relative thin portion 6 to deform or bend. There is a risk of Therefore, when the protrusion (recess) is provided on only one side surface, it is preferable to provide it near the central axis so as to obtain a molded product shown in FIG. 12, for example.

[0025]

As described above, the hollow resin molded product of the present invention has a through recess in the thick portion of the side wall of the hollow portion, which has pressure resistance against the load applied to the molded product. Therefore, it is possible to prevent deformation and damage of the molded product.
In particular, even when two-color molding is performed to improve the appearance and feel, the injection pressure can be sufficiently endured. When the thick-walled region having the penetrating recess is arranged in the hollow portion so as not to face each other, the reinforcing effect of the hollow portion can be further improved.

Further, the mold of the present invention has a protrusion for forming a penetrating recess provided in the thick portion of the side wall of the hollow portion. The protrusion is in contact with the opposing cavity surface or from the opposing cavity surface. Since it is in contact with the projection, it is not deformed by the injected resin pressure or the gas injection pressure, and it is possible to form a predetermined reinforcing through recess without hindering the demolding of the molded product.

[Brief description of drawings]

FIG. 1 is an overall perspective view showing an example of a hollow resin molded product of the present invention,

FIG. 2 is a sectional view taken along line 1A of FIG.

FIG. 3 is a sectional view taken along line 1B of FIG.

FIG. 4 is a vertical sectional view showing a mold of the present invention,

FIG. 5 is a vertical cross-sectional view showing another embodiment of the mold of the present invention,

FIG. 6 is a longitudinal sectional view showing still another embodiment of the mold of the present invention,

FIG. 7 is a vertical sectional view showing still another embodiment of the mold of the present invention,

8 is a sectional view showing another embodiment corresponding to FIG.

9 is a sectional view showing another embodiment corresponding to FIG. 2,

10 is a sectional view showing still another embodiment corresponding to FIG.

11 is a sectional view showing still another embodiment corresponding to FIG.

12 is a sectional view showing still another embodiment corresponding to FIG.

[Explanation of symbols]

 4 Penetrating concave part 5 Thick part area 7 Protrusion 8 Movable type 9 Fixed type 10 Hollow part

Claims (4)

[Claims] 1. A hollow resin molded product obtained by gas injection injection molding, characterized in that it has a hollow side wall thick-walled region, and a through recess is provided in the thick-walled region. Hollow resin molded product. 2. A hollow resin molded article obtained by gas injection injection molding, which has a hollow side wall thick-walled area in a non-face-to-face manner across a central axis in the longitudinal direction of the hollow portion, and the thick-walled portion. A hollow resin molded product characterized in that a through recess is provided in a region. 3. A mold for hollow resin moldings comprising a fixed mold for gas injection injection molding and a movable mold, wherein the fixed mold and / or
Alternatively, the mold for producing a hollow resin molded product according to claim 1, wherein a plurality of protrusions are arranged on the cavity surface of the movable mold so as to be in contact with the facing cavity surface or the protrusion surface. 4. A mold for a hollow resin molded product comprising a fixed mold for gas injection injection molding and a movable mold, the fixed mold and / or
3. The hollow resin according to claim 2, wherein a plurality of protrusions are arranged on the cavity surface of the movable mold so as to be in contact with the opposing cavity surfaces, and are arranged in a non-face-to-face manner with the central axis in the longitudinal direction of the cavity interposed therebetween. Mold for manufacturing molded products.