JPS62111711A - Synthetic resin molded article - Google Patents

Abstract

PURPOSE:To prevent generation of a weld by making an injection flow velocity of a resin material uniform, by providing a thin part whose thickness is specific on a thick part of a molded article. CONSTITUTION:In relation to a cross-sectional area S in a general surface 3 of a molded article 1, a cross-sectional area S1 in a rib 2 and a cross-sectional area S2 in the edge part side of the rib 2, the S2 which is a thin part and satisfies a relation of S1/2<=S2<=S is formed. As a flow velocity 4 of a material to be injected to the thick part S1 becomes close to that of the general surface 3 as per a broken line by the thin part S2 at the time of injection molding and the flow velocity becomes uniform by varying liquid resistance at both parts, generation of weld at a confluent part of the material is prevented. In addition to the above, as a thickness difference of the material can be varied by making a quality of the synthetic resin molded article constant always, design properties and strength can be varied freely.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a synthetic resin molded product that can prevent welds from occurring in the thick parts of the synthetic resin molded product obtained by injection molding.

[Conventional technology]

Conventionally, in synthetic resin molded products obtained by injection molding, when the molten synthetic resin material is injected from the injection nozzle into the molding space of the mold, the synthetic resin material joins the part shown in Figs. 4 and 5. Weld lines as shown in FIG. 6 and FIG. 6 may occur.

In FIG. 4, reference numeral 40 denotes a synthetic resin molded product obtained by injection molding, and a thick-walled rib 41 is integrally formed at the edge of this synthetic resin molded product 40. When the synthetic resin molded article 40 having this shape is molded by injection molding, the thickness of the rib 41 portion is thicker than that of the general surface 42, so that the synthetic resin material flows along the general surface 42 as shown by the broken line 43. The synthetic resin material flows faster toward the ribs 41 than the forming synthetic resin material, and a weld 45 occurs at the merging portion 44.

Further, FIGS. 5 and 6 are examples in which a circular convex portion 51 with letters or the like is formed on the general surface of a synthetic resin molded product 50. When a synthetic + A4 A4 shaped product 50 having such a shape is molded by injection molding, the synthetic resin material around the convex portion 51 moves faster toward the convex portion 51 (as shown by the broken line 52) than the synthetic resin material forming the general surface 53 A weld 55 occurs at the flow and confluence site 54.

Due to the above, in order to prevent welds that occur in areas with uneven wall thickness of synthetic resin molded products, we have taken measures by changing molding conditions such as the injection speed of the synthetic resin material injected into the molding space. Countermeasures have been taken, such as methods of reducing the thickness of synthetic resin molded products, and methods of product design to reduce the difference in wall thickness of synthetic resin molded products.

[Problem that the invention seeks to solve]

However, the former method of changing the molding conditions has the disadvantage that variations occur in the molding conditions and that a stable synthetic resin molded product cannot be obtained. In addition, in the latter method of reducing the difference in wall thickness of synthetic resin molded products, not only the design of the synthetic resin molded products is impaired, but also
There is a problem that cannot be satisfied in terms of strength.

Therefore, the present invention has been made to solve the above-mentioned problems, and by providing a thin part with a specific thickness in the thick part of a synthetic resin molded product, the flow velocity of the synthetic resin material is made uniform, The objective is to maintain a constant quality of synthetic resin molded products and to satisfy them in terms of design and strength.

[Means for solving problems]

That is, in the synthetic resin molded product according to the present invention,
A synthetic resin molded product obtained by injection molding, the thick part of the synthetic resin molded product has 1AS1≦S, ≦S (S d: cross-sectional area of the general surface part, s: cross-sectional area of the thick part, S2: thin-wall part). A thin portion S2 is provided that satisfies the relationship (cross-sectional area).

[Effect]

In such a synthetic resin molded product, during injection molding, the thin part formed in the thick part of the synthetic resin molded product
The flow velocity of the synthetic resin material injected into the thick part becomes close to the flow velocity in the general surface part, and the flow velocity of the synthetic resin material in both parts becomes uniform. Therefore, welds are prevented from occurring at the merged portion of the synthetic resin material.

〔Example〕

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

(First Example) FIG. 1 is a perspective view illustrating a first example of a synthetic resin molded product according to the present invention.

In FIG. 1, ``■'' is a synthetic resin molded product, and a rib 2 is formed near the edge of this synthetic resin molded product 1. In FIG. The cross-sectional area of the general surface 3 of this synthetic resin molded product 1 is S, and the cross-sectional area of the rib 2 is thickest, S. Further, the cross-sectional area of the end edge side of the rib 2 is S, which is the thinnest. As a result, a thin wall portion s2 satisfying the relationship of S work≦S2≦S is formed in the thick wall portion S1 of the synthetic resin molded product 1.

When a synthetic resin molded product having the above-mentioned structure is molded by injection molding, the flow 4 of the synthetic resin material injected into the thick part sl by the thin part S2 during injection molding is as shown by the broken line. - The flow velocity becomes close to the flow velocity at the third portion of the membrane surface, and the flow resistance of the synthetic resin material at both parts changes and the flow velocity becomes uniform. Therefore, welds are prevented from occurring at the merged portion of the synthetic resin material.

(Second Embodiment) FIG. 2 is a plan view illustrating a second embodiment of the synthetic resin molded product according to the present invention, and FIG. 3 is a sectional view taken along the line 2--2 in FIG.

In FIGS. 2 and 3, reference numeral 5 is a synthetic resin molded product, and the general surface 6 of this synthetic resin molded product 5 has a circular convex portion 7 formed by a pattern, etc. Two recesses 8 are formed. The cross-sectional area of the general surface 6 of this synthetic resin molded product 5 is S, and the convex portion 7
The cross-sectional area at is assumed to be Sl, which is the thickest. Further, the cross-sectional area of the recess 8 in the projection 7 is the thinnest s
It is said to be 2. As a result, the synthetic resin molded product 5 has a structure in which a thin wall portion S2 satisfying the relationship IAS1≦S2≦S is formed in a thick wall portion S1.

When a synthetic resin molded product having the above-mentioned configuration is molded by injection molding, the flow 9 of the synthetic resin material injected into the thick part Sl by the thin part S2 during injection molding is as shown by the broken line. -The flow velocity becomes close to that of the membrane surface 6, and the flow resistance of the synthetic resin material at both parts changes, so that the flow velocity becomes uniform.

Therefore, welds are prevented from occurring at the merged portion of the synthetic resin material.

〔Effect of the invention〕

As explained above, in the synthetic resin molded product according to the present invention, since the thin wall portion with a specific thickness is provided in the thick wall portion of the synthetic resin molded product, the flow velocity of the synthetic resin material injected into the thick wall portion is reduced. The thin wall portion makes the flow velocity close to that of the general surface, which has the effect of making the flow velocity of the synthetic resin material uniform in both parts.

In addition, in the synthetic resin molded article according to the present invention, the flow velocity at the merging portion of the synthetic resin material can be made uniform, so that welding can be prevented from occurring.

Furthermore, in the synthetic resin molded product according to the present invention, welding can be prevented without changing the molding conditions such as the injection speed of the synthetic resin material, so the quality of the synthetic resin molded product can always be kept constant. There is an effect that can be done.

Furthermore, in the synthetic resin molded article according to the present invention, the difference in wall thickness of the synthetic resin material can be changed, so there is an effect that the design and strength can be changed freely.

Further, in the synthetic resin molded product according to the present invention, since the shape is changed locally, there is an effect that restrictions on the design of the synthetic resin molded product can be reduced.

[Brief explanation of drawings]

FIG. 1 is a perspective view illustrating a first embodiment of a synthetic resin molded product according to the present invention. FIG. 2 is a plan view illustrating a second embodiment of the synthetic resin molded product according to the present invention. FIG. 3 is a sectional view taken along line mm in FIG. 2. FIG. 4 is a perspective view illustrating a conventional synthetic resin molded product. FIG. 5 is a plan view illustrating another example of a conventional synthetic resin molded product. FIG. 6 is a sectional view taken along line VI-VI in FIG. 5. l-...Synthetic resin molded product 2-Rib 3--General surface 4-Flow of synthetic resin material to s
--General surface section cross-sectional area Sl-... Thick wall section cross-sectional area S2
- Thin section cross-sectional area Applicant: Toyota Motor Corporation 1-m = Synthetic J11 fat area product S ---- General surface section cross-sectional area 4.
Containing dark blue fat and hA and Fig. 2 Koj prisoner Fig. 3

Claims (1)

[Claims] A synthetic resin molded product obtained by injection molding, where the thick part of the synthetic resin molded product has 1/2S_1≦S_2≦S.
(S: General surface section cross-sectional area, S_1: Thick wall section cross-sectional area, S_2
: A synthetic resin molded product characterized by having a thin-walled part S_2 that satisfies the relationship (cross-sectional area of the thin-walled part)