JPH08183061A - Hollow product made of synthetic resin and manufacture thereof by injection molding method - Google Patents

Abstract

PURPOSE: To provide a manufacture of a hollow product made of a synthetic resin by an injection molding method, which causes no deformation of a joint even in the case of injection under a high injection pressure, can obtain a sufficient joint strength and, moreover, can perform molding even in the case of the small number of gates. CONSTITUTION: In molding, a flanged part 5 having a shape of projecting outward from a container part is formed integrally with a first semi-finished product 1, and, in a similar manner, a flanged part 12 having a shape of projecting outward from the periphery of a plate part 11 is also formed integrally with a second semi-finished product 10. In forming, the flanged parts 5, 12 of the first and second semi-finished products 1, 10 are held in a state that they are superposed on each other by molds 20, 30, and molten resin is injected into a cavity 34 defined between the flanged parts 5, 12 to make the first and second semi-finished products into one body.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a first semi-molded article and a second semi-molded article.
Hollow product made of synthetic resin in which a semi-molded product is joined and a first semi-molded product and a second semi-molded product in the primary molding, and a first semi-molded product and a second semi-molded product in the secondary molding The present invention relates to a method for producing a hollow product made of a synthetic resin by an injection molding method, which comprises integrally manufacturing a hollow product by injection molding.

[0002]

2. Description of the Related Art Blow molding, gas injection and the like are known as methods for producing hollow molded articles made of synthetic resin, and the applicant of the present invention has disclosed, for example, in Japanese Unexamined Patent Publication No. 6-238707.
No. 1 proposed a method of manufacturing a synthetic resin hollow molded product using an injection molding machine. This injection molding machine is used to manufacture a synthetic resin hollow molded article by joining a pair of semi-hollow molded articles.
This is a method of obtaining individual hollow molded products, and by this manufacturing method, as shown in FIG. 5, the hollow molded product is molded into two half-hollow products H and J in the primary molding, and the mold is made. The semi-hollow products H and J are attached to K and L so as to abut each other when the mold is clamped, and then the mold is clamped to inject the molten resin from the sprue M into the ring-shaped joint recess N of the split part. A hollow molded product made of synthetic resin, in which the semi-hollow products H and J of 20% are integrated, is obtained.

[0003]

According to the manufacturing method using an injection molding machine proposed by the present applicant, a completely sealed hollow molded product made of synthetic resin can be produced and a hollow with a uniform wall thickness. Molded parts can also be made. In addition, there are many advantages such as being able to deal with complicated shapes. However, some points need to be improved. For example, in this method, the divided portions are abutted, and the molten resin is injected into the ring-shaped joint concave portion N of the divided portion to integrate them, so that the strength of the joint portion can be determined from the shape of the joint portion of the pair of semi-hollow molded products. Problems such as being unable to raise, deforming and leaking may occur. Further, conventionally, since the molten resin is simply injected and joined, there is a problem in the appearance of the joined portion. More specifically, the pressure of the molten resin to be injected also directly acts on the joint portion which is not supported by the molds K and L as indicated by the arrow in FIG. Since the split parts of the semi-hollow products H and J are joined by the molten resin to be injected, the split parts are partially melted by the temperature of the molten resin. As described above, the joint portion is partially melted, and the resin pressure acts, so that the joint portion may be deformed. When deformed, the molten resin may leak inside due to pressure from the melted divided portion. If it leaks, not only the joint strength will decrease, but also the shape will be impaired and the commercial value will decrease. Therefore, the injection speed or pressure, the temperature of the molten resin, and the like are restricted, and the strength of the joint may be insufficient. Further, since the injection pressure has to be lowered, the filling distance is shortened and a plurality of gates must be provided. To avoid this, if the wall thickness of the divided portion is increased, the amount of resin will increase. The present invention
It is intended to provide a synthetic resin hollow product and a method for producing the same that solves the above-mentioned problems, specifically, to provide a synthetic resin hollow product by a large injection molding method having a large bonding strength, Another object of the present invention is to provide a synthetic resin hollow product manufactured by an injection molding method, which has a high joint strength and an improved aesthetics of the joint. In addition, a method for producing a hollow synthetic resin product by injection molding, which does not deform the joint even when injected with a high injection pressure, can obtain sufficient joint strength, and can be molded even with a small number of gates. It is also intended to be provided.

[0004]

In order to achieve the above object, a synthetic resin hollow product according to the present invention is a synthetic resin hollow product in which a first semi-molded product and a second semi-molded product are joined. The first semi-molded product and the second semi-molded product are a flange part projecting outward from the container part of the first semi-molded product and an outer part from the periphery of the second semi-molded product. It is configured such that the flange portion protruding inward is joined and integrated by injection molding. In the invention according to claim 2, the front end surface portion of the flange portion according to claim 1 is covered with the injected resin for joining. In the invention according to claim 3, the first semi-molded product and the second semi-molded product are molded in the primary molding, and the first semi-molded product and the second semi-molded product are molded by the injection molding method in the secondary molding. A method for manufacturing a synthetic resin hollow product for integrally manufacturing a hollow product, wherein in the primary molding, a flange portion projecting outward from a container portion is integrally formed with the first semi-molded product. Similarly, the second semi-molded product is also integrally formed with a flange portion having a shape projecting outward from the periphery, and the flange parts of the first and second semi-molded products are superposed by a mold in the secondary molding. The first and second half-molded products are integrated with each other by injecting a molten resin into the cavity between the flange portions. The invention according to claim 4 is the primary molding according to claim 3, wherein the flange portion of the first semi-molded product is on the inner peripheral surface side and the flange portion of the second semi-molded product is on the outer peripheral surface side with a step of a predetermined depth. In the primary molding according to claim 3 or 4, the inner peripheral surface side of the flange portion of the second semi-molded product tapers outwardly in a taper shape. Molded to have parts.

[0005]

EXAMPLE First, a hollow synthetic resin product according to this example will be described with reference to FIG. According to the present embodiment, the synthetic resin hollow product is formed from the first semi-molded product 1 and the second semi-molded product 10. The first semi-molded product 1 is molded so as to have a container portion 4 from a bottom wall 2 and peripheral walls 3, 3, .... The peripheral walls 3, 3, ... Are extended, and the flange portion 5 protruding rightward in the drawing from the container portion 4,
5, ... Are integrally molded. Flange parts 5, 5,
The inner peripheral surface of ... Is cut off in two steps so as to have a step portion.

The second semi-molded product 10 is formed from a disk portion or a flat plate portion 11 in a substantially lid shape. And the flat plate part 1
1 is integrally formed with a flange portion 12, 12 ... Which protrudes to the right in FIG. 1B from a position inside by a predetermined distance so as to have a step from the outer peripheral surface of 1. First
The flange portions 5, 5, ... Of the semi-molded product 1 and the second semi-molded product 10
, And the flange portions 12, 12, ... Of the first semi-molded product 1 are overlapped as shown in FIG.
And the flange portions 12, 12 of the second semi-molded product 10,
A cavity is formed between the flange portions 5, 12, ... By the step portion of. And the flange portion 5,
The molten resin S is injected into the cavity while the outer peripheral surfaces of 5, ... And the inner peripheral surfaces of the flange portions 12, 12 are held by the mold, and the first semi-molded product 1 and the second semi-molded product 10 are , The flange portions 5, 12, ... Are integrated.

According to the present embodiment, the flange parts 5, 5, ... Of the first semi-molded product 1 are from the container part 4, and the flange parts 12, 12, ... Of the second semi-molded product 10 are from the flat plate part 11. Since each is formed in a protruding shape, the protruding flange portions 5, 12, ... Can be sandwiched between molds for injection. Therefore, a synthetic resin hollow product having high bonding strength can be obtained. The second semi-molded product 10 is not limited to a flat plate-shaped product, and the inner peripheral surfaces of the flange portions 12, 12, ... Are held by a mold as shown in FIG. 3 described later. If space can be secured, 1 in (b) of Fig. 1
Obviously, a bowl-shaped bulge inward as shown by a dotted line or outward as shown by a dotted line can be similarly applied. Further, in the embodiment shown in FIG. 1, the front end surfaces of the flange portions 5, 12, ... Have a three-layer structure and are exposed, but this front end surface is covered with a resin S that is injected for joining to give a beautiful appearance. It can also be improved. Furthermore, although a box-shaped synthetic resin hollow product is shown in FIG. 1, it is obvious that the present invention is not limited to this shape and can be carried out, for example, with a tubular synthetic resin hollow product.

Next, an embodiment of the manufacturing method of the present invention will be described. In the present embodiment, the synthetic resin hollow product is manufactured by primary molding and secondary molding. That is, in the primary molding, a first semi-molded product having a container part and a second semi-molded product having a flat plate part.
A semi-molded product is molded. Then, in the secondary molding, the first semi-molded product and the second semi-molded product are joined by an injection molding method. The primary molding method for forming the first semi-molded article and the second semi-molded article and the mold used to carry out the method are not shown in the figures. A conventionally known or well-known method can be applied to the primary molding. For example, a fixed mold, a slide mold that moves relative to the fixed mold, and a movable mold that is matched with the slide mold, as described in JP-A-62-87315 proposed by the present applicant, are provided. It can also be used to form a pair of first and second semi-molded articles. Then, when the above-mentioned mold device is used, the slide mold is moved toward the movable mold so that the flange part of the first semi-molded product molded by the primary molding is abutted against the flange part of the second semi-molded product. It can be moved for secondary molding. In addition, a pair of first and second semi-molded products are respectively formed by a pair of dies by primary molding, and the flange portions of the first and second semi-molded products are butted against each other in the secondary molding. As described above, the pair of molds can be moved or rotated together.

As described above, as the molds used for the primary molding and the secondary molding, conventionally known or well-known molds can be applied. Therefore, FIG. 2 shows a pair of first semi-molded molds formed by the primary molding. Item 1 and the second semi-molded item 10 are shown. Further, FIG. 3 schematically shows only a simplified mold for secondary molding, and the mold clamping device, the injection machine and the like are not shown in the drawing.

First semi-molded product 1 molded by primary molding
In the present embodiment, as shown in FIG. 2A, the container is molded as a container with the right end opened. Ie the first
The semi-molded product 1 is molded from a bottom wall 2 and a peripheral wall 3 to have a container portion 4. Then, the peripheral wall 3 is extended to integrally form a flange portion 5 protruding from the container portion 4 to the right in the drawing. The inner peripheral surface of the flange portion 5 is cut off in two steps so as to have the step portions 6 and 7.

The second semi-molded product 10 is formed from a disk portion or a flat plate portion 11 in a substantially lid shape. And the flat plate part 1
A cylindrical flange portion 12 that protrudes rightward in FIG. 2B is integrally formed from a position inside a predetermined distance so as to have a step portion 14 from the outer peripheral surface of 1. First
Step 7 of flange 5 of semi-molded product 1 and second semi-molded product 1
The flange portion 5 of the flange portion 0 of 0 and the step portion 14 of the flange portion 12,
A cavity 34 is formed between 12 as will be described later.

The secondary molding die for joining the first and second half-molded products 1 and 10 is composed of a pair of dies 20 and 30 as shown in FIG. The mold 20 has
The bottom wall 2, the peripheral wall 3 and the flange portion 5 of the first semi-molded product 1
The cavity 21 to which is fitted and the other die 30 are
Cores 31 that fit inside the flat plate portion 11 and the flange portion 12 of the second semi-molded product 10 are formed, respectively. Further, a shallow cavity 34 'is provided around the core 31 so as to correspond to the end faces of the flange portions 5 and 12 of the first and second half-molded products 1 and 10. A well-known locate plate 32 is attached to the mold 30.
From the flange parts 5, 12 of the first and second half-molded products 1, 10.
The sprue 33 communicating with the cavity 34 formed in 1. is formed.

Next, an example in which the first and second half-molded products 1 and 10 are joined by the injection molding method using the molds 20 and 30 will be described. As shown in FIG. 3, the mold 2
The first semi-molded product 1 is mounted on the cavity 21 of 0 so that the flange portion 5 is located on the parting surface side. Similarly, the second semi-molded product 10 is mounted on the core 31 of the other mold 30. And using a mold clamping machine not shown in the figure,
Tighten the mold. Then, the circumferential portion of the flat plate portion 11 of the second semi-molded product 10 comes into close contact with the step portion 5 of the first semi-molded product 1, and the insides of the flange portions 5, 12 of the first and second semi-molded products 1, 10 are in contact with each other. A cavity 34 is formed in the. Flange parts 5, 1
The outer surface of 2 is supported by the molds 20 and 30.

Next, the molten resin is injected from the injection machine. As is well known, the molten resin is injected from the injection cylinder through the sprue 33 and the like into the cavity 34. Then, the first and second half-molded products 1 and 10 are joined at the flange portions 5 and 12. After cooling and solidification, the molds 1 and 10 are opened in a conventional manner to take out the hollow synthetic resin product.

According to this embodiment, various effects can be obtained.
For example, the outer peripheral surface of the flange portion 5 of the first semi-molded product 1 is formed by the cavity 21 of the mold 20, and the second semi-molded product 10
Since the inside of the flange portion 12 is supported by the core 31 of the mold 30, even if the high temperature molten resin is injected into the cavity 34 under high pressure, the flange portions 5 and 12 are not deformed. Since high-temperature and high-pressure molten resin can be injected, hollow products made of synthetic resin with high joint strength can be obtained.
Further, since it does not deform, the molten resin does not leak and the commercial value is not impaired. Furthermore,
According to this embodiment, since the shallow cavity 34 'is formed at a position corresponding to the flange portions 5 and 12 of the mold 30, the end faces of the flange portions 5 and 12 are covered with the injected resin for joining. The effect of improving the aesthetics of the end face is obtained. The reference numeral 33 'in FIG. 3 indicates a side gate, but the side gate can also be used for injection.

FIG. 4 shows the first molded by the first molding.
Another embodiment of the semi-molded product and the second semi-molded product is shown in part in the combined state. Elements similar to those of the embodiment described with reference to FIGS. 2 and 3 will be given the same reference numerals with alphabet letters “a, b and c” to avoid duplicate description, but the implementation shown in FIG. According to the example,
The inner peripheral surface of the flange portion 5a of the first semi-molded product 1a is cut off in one step, and the flange portion 5a is formed with a recess in the thickness direction or the longitudinal direction.
On the other hand, the outer peripheral surface of the flange portion 12a of the second semi-molded product 10a is flat and protrudes in both directions from both sides of the flat plate portion 11a. The inside of the flange portion 12a is a tapered portion 13a whose diameter is gradually increased. The other end of the flange portion 12a is adapted to fit in the recess of the flange portion 5a. Flange portion 1 formed in this way
The diameter of the outer peripheral surface of 2a is the flange portion 5 of the first semi-molded product 1a.
It is smaller than the inner diameter of a. As a result, the cavity 34a is formed.

Also in the above embodiment, it is apparent that a hollow product made of synthetic resin can be obtained by holding the flange portions 5a and 12a with a mold and injecting the molten resin into the cavity 34a in the same manner. According to this embodiment, the second semi-molded product 10
Since the taper portion 13 is formed on the flange portion 12a of "a", it is possible to obtain the effect that the hollow synthetic resin product can be easily removed from the core of the mold. In addition, the cavity 34a of the present embodiment
Is slightly different from the above-mentioned embodiment, and the second semi-molded product 10
A part of the flange portion 12a of a has a shape that is not supported by the mold. However, since the finger pressure of the cavity 34a in the unsupported portion acts in the thickness direction of the flat plate portion 11a, the flange portion 12a will not be deformed even if the high temperature and high pressure molten resin is injected. .

FIG. 4B shows the first and second half-molded products 1
An example is shown in which the shape of the flange portions 5b and 12b of b and 10b is simple. According to this embodiment, the inside of the flange portion 5b of the first semi-molded product 1b is simply cut to a predetermined depth so as to have the step portion 8b in order to form the cavity 34b. Further, the flange portion 12b of the second semi-molded product 10b merely stands up.
According to this embodiment, the effect of simplifying the die for primary molding can be obtained. It should be noted that, also in this embodiment, the injection tree finger pressure can be increased, so that sufficient bonding strength can be obtained.

In the embodiment shown in FIG. 4C,
The flange portion 5c of the first semi-molded product 1c has a tapered inner peripheral surface, and the flange portion 12c of the second semi-molded product 10c has a tapered outer peripheral surface. As a result, a cavity 34c having a triangular cross section is formed. According to the above-described embodiments, a part of the tree finger pressure in each of the cavities 34, 34a, 34b is caused by the peripheral walls 3, 3a, 3b of the first semi-molded product 1c.
According to the present embodiment, the tree finger pressure acts on the taper surface, and the first semi-molded product 1
The effect that it hardly acts on the peripheral wall 3c of c is obtained.

[0020]

As described above, the hollow synthetic resin product according to the present invention is formed by joining the first semi-molded product and the second semi-molded product. In the second half-molded product, the flange portion protruding outward from the container portion of the first semi-molded product and the flange portion protruding outward from the periphery of the second semi-molded product are integrated. Therefore, when joining by injection molding, both flanges can be supported by a mold to inject high-temperature, high-pressure molten resin. Therefore, the strength of the joint portion of the synthetic resin hollow product according to the present invention is high. Further, according to the invention of claim 2, since the tip end surface portions of the flange portions of the first semi-molded product and the second semi-molded product are covered with the joined injection resin, the joint surface is widened and the joint strength is increased. It is getting bigger and the aesthetics of the joint is getting better. According to the invention of the manufacturing method as set forth in claim 3, in the primary molding, the first semi-molded product is integrally formed with the flange part projecting outward from the container part, and the same is applied to the second semi-molded product. A flange portion outwardly protruding from the surroundings is integrally formed, and in the secondary molding, when a molten resin is injected between the flange portions of the first and second half-molded products to be joined and integrated, Since the flange portions of the two-half molded products are held in a state of being overlapped with each other by the mold, the high temperature and high pressure molten resin can be injected. Therefore, it is possible to obtain a synthetic resin hollow product having a large strength at the joint portion. Further, since the flange portions of the first and second half-molded products are held in a state of being overlapped with each other by the mold and injected, the flange portion is not deformed and the resin does not leak. Furthermore, since the injection can be performed at a high pressure, the filling distance becomes long and the filling can be performed even if the number of gates is small. Therefore, the effect of simplifying the mold is also obtained. According to the invention of claim 4, in the primary molding, the flange portion of the first semi-molded product has a step portion on the inner peripheral surface side, and the flange portion of the second semi-molded product has a step portion of a predetermined depth on the outer peripheral surface side. Thus, the surface area of the cavity injected during the secondary molding is evenly distributed to the first and second half-molded products. That is, the bonding surface areas of the first and second half-molded products become equal. Therefore, in addition to the effect of the invention described in claim 2, the effect that the bonding strength becomes uniform can be obtained. According to the invention of claim 5, in the primary molding, since the inner peripheral surface side of the flange portion of the second semi-molded product is molded so as to have a taper portion that expands outward in a tapered shape, it is joined by the secondary molding. The effect that the synthetic resin hollow product is easily removed from the mold is added.

[Brief description of drawings]

FIG. 1 is a view showing an embodiment of a synthetic resin hollow product according to the present invention, in which (a) is a perspective view showing a part of the cross section, and (b) is a side view showing a part of the cross section. It is a figure.

FIG. 2 is the first and the second molded by the primary molding of the present invention.
It is a figure which shows the example of a semi-molded product, (a) is a 1st semi-molded product, and (b) is sectional drawing which shows the example of a 2nd semi-molded product typically.

FIG. 3 is a cross-sectional view schematically showing a state in which the first and second half-molded products shown in FIG. 1 are secondarily molded.

FIG. 4 is a cross-sectional view schematically showing a part of another example in which the first and second half-molded products formed by primary molding are different from each other.

FIG. 5 is a cross-sectional view showing a conventional method of manufacturing a synthetic resin hollow product.

[Explanation of symbols]

 1 1st semi-molded product 4 Container part 5 Flange part 10 2nd semi-molded product 11, 11a, b, c Flat plate part 12, 12a, b, c Flange part 13a Tapered part 20, 30 Mold 34, 34a, b, c cavity

Claims (5)

[Claims] 1. A hollow synthetic resin product in which a first semi-molded product (1) and a second semi-molded product (10) are joined together, wherein the first semi-molded product (1) and the second semi-molded product The molded product (10) includes a flange portion (5) projecting outward from the container portion (4) of the first semi-molded product (1) and the second semi-molded product (10).
A hollow product made of synthetic resin by an injection molding method in which a flange portion (12) having a shape protruding outward from the periphery is joined and integrated by injection molding. 2. The flange portion (5, 12) according to claim 1.
The end surface of is a synthetic resin hollow product manufactured by injection molding in which the resin injected for joining is covered. 3. A first semi-molded product (1) in the primary molding.
And a second semi-molded product (10) are molded, and in the second molding, the first semi-molded product (1) and the second semi-molded product (10) are integrated by an injection molding method to manufacture a hollow product. A method of manufacturing a hollow product made of synthetic resin according to claim 1, wherein in the primary molding, a flange portion (5) protruding outward from a container portion (4) is integrally formed on the first semi-molded product (1). At the same time, the second semi-molded product (10) is also integrally formed with a flange portion (12) having a shape protruding outward from the periphery, and in the secondary molding, the first and second semi-molded products ( The flange parts (5, 12) of
0, 30) to hold them in a superposed state, and inject the molten resin into the cavity (34) between the flange portions (5, 12) to thereby produce the first and second half-molded products (1, 1).
0) is integrated with a synthetic resin hollow product by an injection molding method. 4. The primary molding according to claim 3, wherein
The flange portion (5) of the semi-molded product (1) is on the inner peripheral surface side, and the flange portion (12) of the second semi-molded product (10) is on the outer peripheral surface side, and a stepped portion (6, 7, 14) A method for producing a synthetic resin hollow product by an injection molding method, the method including molding the hollow product. 5. The primary molding according to claim 3 or 4, wherein the inner peripheral surface side of the flange portion (12) of the second semi-molded product (10) tapers outwardly.
A method for producing a hollow product made of synthetic resin by an injection molding method, which comprises molding to have a).