JP3431325B2 - Injection molded product structure having thin part and thick part - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synthetic resin molded article structure which constitutes a main body shaft of an applicator for discharging contents by being pressed and deformed, and has an injection portion having a thin portion and a thick portion. It relates to a molded article structure.

[0002]

2. Description of the Related Art Generally, in synthetic resin moldings, blow moldings require processing costs which are 2-3 times or more than those of injection moldings. FIG. 6 shows an example of a blow-molded product, which is a main body shaft used for an applicator such as a correction pen. The main body shaft a has a substantially cylindrical shape formed of a substantially uniform thin wall, and has a large diameter portion b having a bottom portion b1 and a small diameter portion d connected to the large diameter portion b via a step c. The small-diameter portion d is composed of a tapered portion e that is slightly tapered from the tip thereof, and a mouth portion f formed at the tip of the tapered portion e.

When this main body shaft a is used for a liquid container of a correction pen, for example, the user mainly presses the small diameter portion d with his fingertip to deform it so that it can be restored, that is, by pumping, so that the contents are corrected. The liquid can be discharged from the mouth portion f side and applied to the surface to be coated.

[0004]

By the way, the wall thicknesses of the bottom portion b1, the large diameter portion b and the small diameter portion d of the main body shaft a are 0.7 to 1.0 mm or more in view of the blow molding process. Desirably, it is difficult to reduce the thickness to 0.5 mm or less, and even if such processing is performed, the processing cost becomes higher.

Therefore, if the main body shaft a is to be formed at low cost by blow molding, the wall thickness becomes thicker, and accordingly, a strong pressing force is required at the time of pumping. Further, even if the thickness is 0.5 mm or less, in blow molding,
Since a reinforcing rib or the like cannot be provided on the inner surface of the main body shaft a, the bending strength of the main body shaft a cannot be increased.

Therefore, it is possible to procure the main body shaft a by injection molding instead of blow molding. In a general injection-molded product, as shown in FIG. 7, the main body shaft g is configured to have a substantially uniform thickness and a relatively large thickness. However, when a pumping action is required like the main body shaft a. As shown in FIG. 8, the easily deformable thin portion h2 must be provided on the main body shaft h.

The main body shaft h shown in FIG. 8 has a shape substantially similar to that of the main body shaft a, and the portion corresponding to the small diameter portion d is formed thinner than the other portions. That is, the main body axis h has a thick portion h1 corresponding to the large diameter portion b.
And a thin portion h2 corresponding to the small diameter portion d, and a thick portion h3 corresponding to the tapered portion e and the mouth portion f.

However, when the present inventor tried to procure the above-mentioned main body shaft h by injection molding, the following problems occurred in the processing of injection molding, and it was difficult to obtain a good product. It was

(1) Injecting a synthetic resin material from the gate i1 or the gate i2. The molding material (hereinafter simply referred to as material) that has entered from the gate i1 at the tip of the thick portion h3 flows smoothly in the thick portion h3, but when it reaches the thin portion h2, the flow resistance increases, and the thick portion h1 further increases. When it reaches, the fluidity deteriorates. For this reason, the pressure is not sufficiently increased at the thick portion h1, and a recess (sink) j1 is generated at the corner of the thick portion h1. Further, in the thin portion h2 having a high flow resistance, the material flows intensively at a place where the flow resistance is a little low, so that the perforated portion j2 often occurs.

That is, in general, in injection molding, since the material "flows and solidifies" in the mold, the principle is to drive the material quickly before it cools, whereas the molded product of the main body shaft h. With the structure, as the material cools, the fluidity deteriorates in the thin portion h2 even during the flow, so that it becomes difficult to transmit the injection pressure to every corner of the mold. When the material is poured from the gate i2, the recessed portion and the perforated portion are similarly generated.

(2) Injecting material from the gate i3. Since the gate i3 is provided in the thin portion h2, the material passes through the thin portion h2 having high flow resistance from the beginning. Therefore, even if the thick parts h1 and h2 on both sides are filled with the material, the internal pressure does not rise sufficiently and the recess j1
Will occur. At the same time, the material tries to flow into the thick portions h1 and h3 on both sides where the flow resistance is low, so that the perforated portion j2 also occurs.

As described above, in the structure of the conventional injection-molded product having the thin portion and the thick portion, the flow resistance of the thin portion eventually becomes high no matter which gate is used to inject the material. In addition, when the material flowing through the thin wall portion flows into the thick wall portion, the fluidity of the material in the thick wall portion is reduced, and the recessed portion or the perforated portion is generated. Therefore, it is difficult to adopt an inexpensive injection-molded product as the main body shaft having a pumping function with the conventional structure of the injection-molded product shown in FIG.

The present invention has been made in view of the above conventional problems, and eliminates the occurrence of a recessed portion in a thick wall portion and a perforated portion in a thin wall portion, and an injection molded product having a uniform wall thickness. It is possible to obtain a good product of the same degree, to have the same pumping characteristics as the blow molded product, and to have a bending strength higher than that of the blow molded product. It is an object of the present invention to provide an injection molded article structure having

[0014]

The present invention has the following constitution in order to achieve the above object. That is, claim 1
Is a synthetic resin molded product structure that constitutes the main body shaft of an applicator that discharges contents by being pressed and deformed, and a thin-walled portion having a substantially tubular shape with a wall thickness of 0.3 mm to 0.8 mm; It is connected to the end of the thin wall and the wall thickness is 1.0
mm-2.0 mm thick section having a substantially tubular shape,
At least one of the inner surface and the outer surface of the thin portion is provided with one or a plurality of ribs that project substantially at right angles to the axial direction and that extend from one end of the thin portion to the other end. It is an injection-molded article structure having a thin portion and a thick portion.

According to a second aspect of the present invention, the width of the rib is set within a range of 1 to 4 times the thickness of the thin portion. It is an injection molded article structure having.

According to a third aspect of the present invention, the radial dimension of the rib is
The injection molded product structure having a thin portion and a thick portion according to claim 1 or 2, characterized in that the thickness is set in a range of 1 to 5 times the thickness of the thin portion.

According to a fourth aspect of the present invention, in a longitudinal sectional view of the rib, a chamfered slope or a rounded portion is provided at a corner where the surface of the thick portion and an end face in the longitudinal direction of the rib intersect. An injection molded product structure having a thin portion and a thick portion according to any one of claims 1, 2 and 3.

According to a fifth aspect of the present invention, in a cross-sectional view of the rib, a chamfered slope or a rounded portion is provided at a corner where the surface of the thin portion and the side surface of the rib intersect.
An injection molded article structure having a thin portion and a thick portion according to any one of claims 1, 2, 3 and 4.

[0019]

According to the first aspect, although the flow resistance once increases when the material flows through the thin portion, the material smoothly flows in the rib and reaches the end portion of the thick portion. That is, since the cooling and solidification of the material in the thin portion is slowed by the rib, this rib serves as a path to the thick portion,
The material is promptly guided to the thick portion, which improves the fluidity and increases the internal pressure in the thick portion. Therefore, the concave portion is not generated in the thick portion, and at the same time, the internal pressure of the thin portion is increased, so that the perforated portion is not generated in the thin portion.

Therefore, the increase in the flow resistance in the thin portion and the decrease in the fluidity in the thick portion are eliminated by the ribs,
Since the material is well filled into every corner of the mold including the thin wall portion and the thick wall portion, a good product having a uniform wall thickness and the same quality as a general injection molded product can be obtained.

Further, since it has a thin-walled portion equivalent to that of the blow-molded product, the pumping characteristics similar to those of the blow-molded product can be obtained. Therefore, by pumping, contents such as liquid can be discharged or the contents can be made uniform. You will be able to mix and mix.

Further, since the main body shaft of the applicator can be procured by injection molding, the main body shaft can be constructed with high dimensional accuracy. Therefore, the connection with other parts such as the tip shaft of the correction pen becomes more reliable.

Further, since the rib is provided in the thin portion, compared with a blow-molded product which is simply formed into a thin wall,
The applicator with higher bending strength can also be obtained.

According to the inventor of the present invention, the pumping action of pressing the thin portion with the fingertip to elastically deform it and then releasing the fingertip to surely restore the original shape is ensured as in the blow-molded article. In order to obtain the thickness, it is considered suitable to set the width of the rib in the range of 1 to 4 times the thickness of the thin portion.

Further, it is desirable that the radial dimension of the rib is set in a range of 1 to 5 times the wall thickness of the thin portion. If the radial dimension is more than the above range, the mold release At that time, the resistance of the molded product may increase and the rib may buckle.

A chamfered slope (C surface) is formed at the corner where the surface of the thick portion and the end surface of the rib in the longitudinal direction intersect.
Alternatively, a rounded portion (R surface) may be provided. In that case, the fluidity of the material flowing from the thin portion to the thick portion is further improved, and the material is more surely filled to improve the quality of the molded product. Excellent action is obtained.

If chamfered slopes or rounded portions are provided at the corners where the surfaces of the thin portions and the side surfaces of the ribs intersect, the flow resistance of the material flowing through the ribs is reduced. The fluidity of the material in the part is improved, and a molded product of higher quality can be obtained. Also, stress concentration at the root of the rib is prevented.

[0028]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a side sectional view of the injection-molded article of the first embodiment seen from the side, and FIG. 2 is a sectional view taken along line II-II in FIG.
(A) is provided with two ribs, and (b) is provided with three ribs. FIG. 3 is an enlarged cross-sectional view of a rib showing the peripheral structure of the rib root portion of FIG.

FIG. 4 is a side sectional view of the injection-molded article of the second embodiment as seen from the side. FIG. 5 corresponds to FIG.
FIG. 5A is a sectional view taken along line V-V, in which (a) is provided with two ribs and (b) is provided with three ribs.

As shown in FIG. 1, the first embodiment is an injection-molded product structure which constitutes the main body shaft 2 of the applicator for discharging contents by being pressed and deformed, and has a wall thickness t1 of 0. Thin portion 4 having a substantially cylindrical shape of 3 mm to 0.8 mm
And a thick-walled portion 6 connected to the front and rear ends of the thin-walled portion 4 and having a substantially tubular shape with a thickness t2 of 1.0 mm to 2.0 mm.
A and 6B are provided, and the inner surface 4a of the thin portion 4 is provided with a plurality of ribs 8 projecting in a direction substantially perpendicular to the axial direction and extending from one end of the thin portion 4 to the other end. It is a thing.

In the present invention, the applicator means a writing tool such as a correction pen using a correction liquid, ink, glue or the like as a coating liquid,
Alternatively, it refers to an applicator that includes a cosmetic tool for applying a cosmetic and that applies the coating liquid to the surface to be coated.
The main shaft of the applicator refers to a liquid container that stores the application liquid and forms the main body of the applicator.

The configuration of each section will be described in detail below. The outer shape of the main body shaft 2 is substantially the same as the main body shaft of a conventional blow-molded product, and can be a substitute for the blow-molded product. The thin portion 4 has a substantially cylindrical shape and serves as a portion that a user holds with a finger when used as an applicator. Thin part 4
A thick portion 6A is continuously formed at the front end portion of the taper. The thick portion 6A has a tapered portion that tapers toward the tip and a cylindrical mouth portion that is continuous with the front end portion of the tapered portion. On the other hand, at the rear end of the thin-walled portion 4, a thick-walled portion 6 </ b> B having a larger inner diameter and outer diameter than the thin-walled portion 4 and forming a substantially cylindrical large-diameter portion is provided.
Are connected through.

The rib 8 extends substantially linearly along the axial direction of the main body shaft 2. The dimension L1 in the longitudinal direction of the rib 8 is
Is set longer than the axial length L2 of the thin portion 4,
Both ends reach the inner surface of each of the thick-walled portions 6A and 6B on the front and rear sides. Further, as shown in FIGS. 2A and 2B, the ribs 8 are provided on the inner surface 4a of the thin portion 4 at two or three locations at equal intervals in the circumferential direction.
The number of ribs 8 is not limited to this embodiment, and four or more ribs may be arranged in the circumferential direction, or only one rib may be provided.
According to the present inventor, considering that the thin portion 4 is pumped, it is desirable that the number of ribs 8 is 2 to 8 arranged at equal intervals. The bottom surface and both side surfaces of the rib 8 may be straight, but may be appropriately drafted if necessary.

Further, as shown in FIG. 2 (a), the rib 8
Width W of the rib 8 is set to a range of 1 to 4 times the wall thickness t1 of the thin portion 4, and the radial dimension H of the rib 8 is also set to the same.
The thickness t1 is set to be 1 to 5 times.

Further, a longitudinal sectional view of the rib 8 (see FIG. 1)
A chamfered slope (C surface) is provided at the corner 10 where the inner surface 6B1 of the thick portion 6B and the longitudinal rear end surface of the rib 8 intersect. The corner portion 10 may be provided with a curved rounded portion (R surface), and in some cases, the corner portion 10 may be rounded up to form a sharp edge.

Further, a cross-sectional view of the rib 8 (see FIG. 3)
A chamfered slope or a rounded portion may be provided at the corner 12 where the inner surface 4a of the thin portion 4 and the side surfaces 8a, 8a of the rib 8 intersect, and the corner 12 is formed into a sharp edge. You may.

According to the structure of the injection-molded article of the first embodiment having the above-mentioned structure, as shown in FIG. 1, for example, the material (polypropylene, ethylene rubber, etc.) is poured from the gate 16 on the mouth side and the main body shaft is injected. When molding 2, the material is
After smoothly flowing through the thick portion 6A composed of the mouth portion and the taper portion, it reaches the front end portion of the thin portion 4. This thin part 4
When the material flows through the material, the flow resistance temporarily increases, but the material flows smoothly in the rib 8 and reaches the rear end portion of the thick portion 6A. That is, since the cooling and solidification of the material in the thin portion 4 is delayed in the rib 8, the rib 8 serves as a path to the thick portion 6B, and the material is quickly guided to the thick portion 6B, whereby the inside of the thick portion 6B is Then, the fluidity becomes good and the internal pressure also increases. Accordingly, no recess is formed in the thick portion 6B, particularly near the step portion 14, and at the same time, the internal pressure of the thin portion 4 is increased, so that the thin portion 4 is not punctured.

Therefore, the increase in the flow resistance of the thin portion 4 and the decrease in the fluidity in the thick portion are eliminated by the ribs 8, and every corner of the mold including the thin portion 4 and the thick portion 6B is reached. The material is filled well, and it is possible to obtain a non-defective product having a uniform wall thickness and the same level as a general injection-molded product.

Since the thin portion 4 equivalent to the blow-molded product is provided, pumping characteristics similar to those of the blow-molded product can be obtained. Therefore, by pumping, contents such as liquid can be discharged or the contents can be discharged. Can be mixed evenly.

Furthermore, since the main body shaft of the applicator can be procured by injection molding, the main body shaft 2 can be constructed with high dimensional accuracy. Therefore, the connection with other parts such as the tip shaft of the correction pen becomes more reliable.

Further, since the rib 8 is provided on the thin portion 4, the rib 8 reinforces the thin portion 4, and therefore has a higher bending strength than a blow-molded product which is simply formed to be thin. The applicator can also be obtained.

According to the inventor of the present invention, the pumping action of the blow-molded product is ensured, as in the blow-molded product, by pressing the thin portion 4 with the fingertip to elastically deform it, and then releasing the fingertip to reliably restore the original shape. In order to obtain the above, it is considered preferable to set the width W of the rib 8 in the range of 1 to 4 times the wall thickness t1 of the thin portion 4.

Further, it is desirable that the radial dimension H of the rib 8 is set within a range of 1 to 5 times the wall thickness t1 of the thin portion 4. If the dimension H in the protruding direction is equal to or more than the above range, There is a risk that the resistance at the time of releasing the mold becomes large and the ribs 8 may buckle or the mold releasing may be deteriorated.

If a chamfered slope (C surface) or rounded portion (R surface) is provided at the corner 10 where the inner surface 6B1 of the thick portion 6B and the rear end surface of the rib 8 in the longitudinal direction intersect, The flowability of the material flowing from the thin portion 4 to the thick portion 6B is further improved, and the material is more surely filled and the quality of the molded product is improved, which is a remarkable effect.

When a chamfered slope or a rounded portion is provided at the corner 12 where the inner surface 4a of the thin portion 4 and the side surface 8a of the rib 8 intersect, the flow resistance of the material flowing through the rib 8 is reduced. Therefore, the fluidity of the material in the thin portion 4 is improved, and a molded product of higher quality can be obtained. Also, stress concentration at the root of the rib 8 is prevented.

Even when the material is poured into the gate 16 on the mouth side from the gate 18 at the rear end of the thick portion 6B,
By flowing the material through the ribs 8, the fluidity and the internal pressure of the material in the thick portion 6A and the thin portion 4 are improved, so that a high quality injection-molded product can be obtained as in the case where the material is poured from the gate 16.

Next, the second embodiment will be described. In addition,
Since the structure of the second embodiment other than the rib 8'is substantially the same as that of the first embodiment, the same reference numerals are given and the description thereof is omitted.

In the second embodiment, as shown in FIG.
A rib 8'is linearly and axially extended on the outer surface 4b of the thin portion 4. The ribs 8'may be provided at two or three locations side by side in the circumferential direction, or one or four or more ribs 8'may be provided as in the first embodiment. Also, FIG.
As shown in (a) and (b), the width W and the radial dimension H of the rib 8 ′ are the same as those of the rib 8. Further, in a cross-sectional view of the rib 8 ′, at the corner where the outer surface 4b of the thin portion 4 and the side surfaces 8′a, 8′a of the rib 8 ′ intersect, a chamfered slope or the same as in the first embodiment. A rounded portion may be provided, or the corner portion may be directly formed as a sharp edge.

Needless to say, according to the structure of the second embodiment, the same effect as that of the first embodiment can be obtained. However, in the second embodiment, the rib 8'is provided on the outer surface of the main body shaft 2 outwardly. Since it is provided so as to project, the rib 8 ′ also plays a role of preventing rotation of the main body shaft 2 when the user holds the thin portion 4 and applies it. Therefore, the user can hold the applicator firmly and apply. Also,
If the ribs 8'are spirally provided on the outer surface 4b of the thin portion 4, the effect of preventing the user's fingertips from slipping can be obtained. Also, the ribs 8'may be formed intermittently.

The first and second embodiments described above are preferred embodiments of the present invention, and the technical scope of the present invention is not limited to this embodiment. For example, in the first and second embodiments,
The present invention is applied to the main body shaft 2 in which the thick-walled portions 6A and 6B are connected to the front and rear ends of the thin-walled portion 4, but in contrast to this,
It may be a main body shaft in which a thick portion is formed only at one of the front and rear ends of the thin portion 4. Also, even if the main body shaft is not cylindrical,
It may be a tubular shape such as an outer polygonal shape or an elliptical cross section.

[0051]

As described above, according to the present invention, an injection-molded product having a thin portion and a thick-walled portion has a quality comparable to that of a general injection-molded product having a uniform thickness and blow molding. Since it is possible to obtain the same pumping characteristics as the product,
Post-processing such as deburring, which is required for blow-molded products, is also unnecessary, and the main shaft of the applicator can be procured for the blow-molded products at a cost of 1/3 to 1/2. It is also possible to obtain an applicator having a bending strength higher than that of the blow molded product.

[Brief description of drawings]

FIG. 1 is a one-sided sectional view of an injection-molded article according to a first embodiment as viewed from the side.

2 is a sectional view taken along line II-II in FIG. 1, in which (a) is provided with two ribs and (b) is provided with three ribs.

FIG. 3 is an enlarged cross-sectional view of a rib showing a peripheral structure of a rib root portion of FIG.

FIG. 4 is a one-sided sectional view of an injection-molded article according to a second embodiment as viewed from the side.

5 is a cross-sectional view taken along line VV in FIG. 4, where (a) is provided with two ribs and (b) is provided with three ribs.

FIG. 6 is a one-sided sectional view of a conventional blow-molded product as viewed from the side.

FIG. 7 is a one-sided sectional view of a conventional injection-molded product as viewed from the side.

FIG. 8 is a one-sided cross-sectional view of an injection-molded product having a thin portion and a thick portion as viewed from the side.

[Explanation of symbols]

2 body axis 4 Thin part 4a Inner surface of thin portion 4b Outer surface of thin part 6A thick part 6B thick part 6B1 Inner surface of thick part 8 ribs 8a Side of rib 8'rib 8'a rib side 10 corners 12 corners t1 Thickness of thin part t2 Thickness of thick part W rib width H rib radial dimension

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ identification code FI B65D 1/32 B65D 1/32 (58) Fields investigated (Int.Cl. ⁷ , DB name) B29C 45/00-45/84 A45D 34/00-34/06 B43K 5/00-5/18 B65D 1/00-1/48

Claims (5)

(57) [Claims] 1. A synthetic resin molded product structure which constitutes a main shaft of an applicator for discharging contents by being pressed and deformed, wherein a thin portion having a substantially cylindrical shape with a thickness of 0.3 mm to 0.8 mm. And the thickness is 1.0 mm and is continuous with the end of the thin portion.
A thick-walled portion having a substantially tubular shape of about 2.0 mm, at least one of an inner surface and an outer surface of the thin-walled portion protruding in a direction substantially perpendicular to the axial direction, and the thin-walled portion. An injection-molded article structure having a thin portion and a thick portion, wherein one or a plurality of ribs extending from one end to the other end are provided. 2. The width of the rib is 1 of the thickness of the thin portion.
The injection molded product structure having a thin wall portion and a thick wall portion according to claim 1, characterized in that the thickness is set to a range of 4 times. 3. The thin portion and the thick portion according to claim 1, wherein the radial dimension of the rib is set in a range of 1 to 5 times the thickness of the thin portion. Injection-molded article structure having a section. 4. A chamfered slope or a rounded portion is provided at a corner portion where a surface of the thick portion and an end surface in the longitudinal direction of the rib intersect in a longitudinal sectional view of the rib. ,
An injection-molded article structure having a thin portion and a thick portion according to any one of claims 1, 2 and 3. 5. A chamfered slope or a rounded portion is provided at a corner where a surface of the thin portion and a side surface of the rib intersect in a cross-sectional view of the rib. ,
An injection molded article structure having a thin portion and a thick portion according to any one of 2, 3 or 4.