JPH07314482A - Resin molded body - Google Patents

Abstract

PURPOSE:To improve the dimensional accuracy by connecting a plurality of plate members at their connection parts and providing a thin wall part at a part of the connection parts. CONSTITUTION:A resin molded body is formed of two plate members 2a, 2b. The end of the plate member 2b is put into contact with the other surface of a plate member 2a and they are connected at their connection parts 3. A part of the connection part 3 is formed with a thin wall part 4 in the form of being thinner than the wall thickness of respective plate members 2a, 2b. In this constitution, even in the case where contraction stresses occur on respective plate members 2a, 2b at the time of a contraction of thermoplastic resin after injection molding, they are absorbed and dispersed by the thin wall thickness 4. Accordingly, any deformation of the plate members 2a, 2b due to the contraction stresses can be prevented. In this instance, the thin wall thickness part 4 is formed by providing a recession on the connection part 3, however, such recession can be available at either one side or both sides of the connection part 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin molded product, and more particularly to a resin molded product having high dimensional accuracy.

[0002]

2. Description of the Related Art Conventionally, resin moldings molded by injection molding a thermoplastic resin have been used. The shape of such a resin molded body may be various shapes depending on the purpose of use. For example, the resin molded body 61 shown in FIG. 10 is a box-shaped resin molded body, and includes a main body portion 62 and a lid portion 67. The main body 62 is
A plate-shaped rectangular bottom member 63 and 4 formed so as to rise from the peripheral edge of the bottom member 63 and connected to each other.
The individual side wall members 64a, 64b, 64c, 64d are provided. Further, the lid portion 67 is joined and continuously provided to the upper end portion of the side wall member 64a, and is rotatable at the joined portion. Such a resin molded body is generally molded by injection molding using a thermoplastic resin.

[0003]

However, in a resin molded product having two or more plate-shaped members and having a joint portion between the members, each member shrinks when the thermoplastic resin shrinks after injection molding. There is a problem that the stresses act on each other to deform the shape of one member or a plurality of members. Taking the above-mentioned resin molded body as an example, as shown in FIG. 11, the side wall members 64b, 64c, 64d are those whose upper end portion is curved inwardly of the main body portion 62 due to the contracting stress from the bottom member 63. Become. For this reason, the dimensional accuracy of the resin molded body is lowered, and it is difficult to obtain a precise resin molded body.

With respect to such shape deformation, it is possible to previously adjust the mold used for injection molding so that desired dimensional accuracy can be obtained in the state after the contraction stress of the bottom portion acts on the side wall member. However, the characteristics of the thermoplastic resin used,
Since the degree of stress deformation varies depending on the thickness of the resin molded body and the like, adjustment with a mold becomes extremely complicated.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a precise resin molding having high dimensional accuracy.

[0006]

In order to achieve such an object, the present invention has at least two plate-shaped members, and has a thin-walled portion in at least a part of a joint portion of each member. And

[0007]

By having a thin-walled portion in at least a part of the joint portion of each member, the thin-walled portion absorbs and disperses shrinkage stress generated in each member when the thermoplastic resin shrinks after injection molding, and the member is deformed. Is prevented.

[0008]

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

FIG. 1 is a perspective view showing an embodiment of the resin molding of the present invention. In FIG. 1, a resin molded body 1 is composed of two plate-shaped members 2a and 2b, and a joint portion 3 having a shape in which an end of the plate-shaped member 2b abuts on one surface of the plate-shaped member 2a The part 3 has a thin part 4. Thin part 4
Is formed thinner than the wall thickness of each plate-shaped member 2a, 2b of the resin molded body 1.

As described above, since the joint portion 3 of the plate-shaped members 2a and 2b has the thin portion 4, the contraction stress is applied to each plate-shaped member 2a and 2b when the thermoplastic resin is contracted after the injection molding. Even if it occurs, the thin portion 4 absorbs and disperses the contraction stress,
It is possible to prevent the plate member from being deformed due to the contraction stress.
In the illustrated example, the thin portion 4 is formed by providing the concave portion only on one side of the joint portion 3, but the concave portion may be provided on both of the joint portions 3, or the concave portions may be intermittently provided.

FIG. 2 is a perspective view showing another embodiment of the resin molding of the present invention. In FIG. 2, the resin molded body 11 has three
Each plate-shaped member 12a, 12b, 12c is provided with a joint portion 13 in which one end of each of the three plate-shaped members 12a, 12b, 12c abuts each other. This joint 13
Has a thin portion 14, and the thin portion 14 is formed thinner than the plate members 12a, 12b, 12c of the resin molded body 11.

As described above, the plate-shaped members 12a, 12b,
Since the joint portion 13 of 12c has the thin wall portion 14, each plate-shaped member 12a, when the thermoplastic resin shrinks after injection molding,
Even if contraction stress is generated in 12b and 12c, the contraction stress is absorbed and dispersed by the thin portion 14, and the plate-shaped member can be prevented from being deformed by the contraction stress. In the illustrated example, the joint 1
Among the three, the thin portion 14 is formed by providing the recessed portion only at the joint portion located between the plate-shaped members 12a and 12c. The position where the recessed portion is provided is between the plate-shaped members 12a and 12b. Alternatively, it may be between the plate members 12b and 12c, or two or more recesses may be provided. Further, the recess may be continuous as in the illustrated example, or may be formed intermittently.

FIG. 3 is a perspective view showing another embodiment of the resin molding of the present invention. In FIG. 3, the resin molding 21 is 3
A joint portion 2 having two plate-shaped members 22a, 22b, 22c, each plate-shaped member being in contact with the end of the other member.
3a, 23b, 23c. Then, the joint portions 23a, 23b, 23c are respectively thin-walled portions 24a, 2b.
It has 4b and 24c. This thin portion 24a, 24
b and 24c are each plate-shaped member 2 that constitutes the resin molded body 21.
It is formed thinner than the wall thickness of 2a, 22b, 22c.

As described above, the plate members 22a, 22b,
The joint portions 23a, 23b, and 23c of 22c are thin portions 24.
Since they have a, 24b, and 24c, the plate-shaped members 22a, 22b, and 22 when the thermoplastic resin shrinks after injection molding.
Even if contraction stress occurs in c, the thin-walled portions 24a, 24b, 2
4c absorbs and disperses the contraction stress, and it is possible to prevent the contraction stress from deforming the plate-shaped members 22a, 22b, 22c (deformation as shown by an imaginary line in FIG. 3). In the illustrated example, the joints 23a, 23b, 23c all have the thin portions 24a, 24b, 24c.
One or two of a, 23b, and 23c may have a thin portion. Further, in the embodiment shown in FIG. 3, the thin portion 24a, 24b, 24c is formed by providing the recessed portion from the inside of the resin molded body 21 to the joint portion, but the present invention is not limited to this. For example, as shown in FIG. 4, the thin-walled portion 24 is formed by cutting a part of the joint from the outside of the resin molded body 21.
You may form a, 24b, 24c. When the appearance of the resin molded body is emphasized, a recess is provided in the joint from the inside of the resin molded body 21 as shown in FIG. 3, and the inner surface of the resin molded body is emphasized (accurate capacity is required. Or a case where there is no liquid pool and good drainage is required), a thin portion can be formed by scraping off a part of the joint from the outside of the resin molded body 21 as shown in FIG. it can. Further, the recess and the scraped portion may be provided continuously to the joining portion or may be intermittent.

FIG. 5 is a perspective view showing another embodiment of the resin molding of the present invention. In FIG. 5, the resin molding 31 is 4
Each plate-shaped member 32a, 32b, 32c, 32d is provided with joint portions 33a, 33b, 33c, 33d in which the end of each plate-shaped member abuts the end of another member. Then, the joint portions 33a, 33b, 33c, 33d
Have thin portions 34a, 34b, 34c, 34d, respectively. The thin portions 34a, 34b, 34c, 34
d is each plate-shaped member 32a, 3 that constitutes the resin molded body 31.
It is formed thinner than the wall thicknesses of 2b, 32c and 32d.

As described above, the plate members 32a, 32b,
Joints 33a, 33b, 33c, 33 of 32c, 32d
Since d has thin portions 34a, 34b, 34c, 34d, even if shrinkage stress occurs in each plate member 32a, 32b, 32c, 32d during shrinkage of the thermoplastic resin after injection molding, the thin portion The contraction stress is absorbed and dispersed by 34a, 34b, 34c, and 34d, and the plate-shaped member 32 is generated by the contraction stress.
It is possible to prevent the deformation of a, 32b, 32c, 32d (deformation as shown by the imaginary line in FIG. 5). In the illustrated example, all of the joint portions 33a, 33b, 33c, 33d have thin-walled portions 34a, 34b, 34c, 34d, but at least one of the joint portions 33a, 33b, 33c, 33d has a thin-walled portion. All you have to do is have it. Further, in the embodiment shown in FIG. 5, the thin portion 34a, 34b, 34c, 34 is formed by providing a recess in the joint portion from the inside of the resin molded body 31.
Although d is formed, it is not limited to this. For example, as shown in FIG. 6, the thin-walled portions 34a, 34b, 34c, 34d may be formed by cutting off a part of the joint from the outside of the resin molded body 31. When the appearance of the resin molded body is emphasized, as shown in FIG. 5, a recess is provided in the joint from the inside of the resin molded body 31 and the inner surface of the resin molded body is emphasized (accurate capacity is required. Or a case where there is no liquid pool and good drainage is required), a thin portion can be formed by scraping off a part of the joint from the outside of the resin molded body 31 as shown in FIG. it can. Further, the recess and the scraped portion may be provided continuously to the joining portion or may be intermittent.

FIG. 7 is a perspective view showing another embodiment of the resin molding of the present invention. In FIG. 7, a resin molded body 41 is a box-shaped resin molded body, and includes a main body portion 42 and a lid portion 47.

The main body portion 42 constituting the resin molded body 41 is
A plate-shaped rectangular bottom member 43 and four plate-shaped side wall members 44 formed so as to rise from the peripheral edge of the bottom member 43.
a, 44b, 44c, 44d. Each of the side wall members is connected to the adjacent side wall member, and a lid portion 47 is connected and connected to the upper end of the side wall member 44a of the side wall members. The lid portion 47 is rotatable at a joint portion with the side wall member 44a, and the side wall members 44b and 4b.
The main body portion 42 can be closed to form a sealed box body while being in contact with the upper end surfaces of the 4c and 44d.

The resin molding 41 of the present invention as described above is
Joints 45a, 45b, 4 between the bottom member 43 and each side wall member
5c, 45d, three joints 45b, 45c,
45d has thin portions 46a, 46b, 46c.
FIG. 8 is a vertical cross-sectional view taken along line VIII-VIII of the resin molding 41 shown in FIG. As shown in FIG. 8, the thin portions 46 a, 46 b, and 46 c are the bottom members 4 of the resin molded body 41.
3. The side wall members 44b, 44c, and 44d are formed to be thinner than their wall thickness.

As described above, among the joints between the bottom member 43 and the side wall members, the thin-walled portions 46a, 46b, 45d are attached to the three joints 45b, 45c, 45d where the side wall members 44b, 44c, 44d are raised. By providing 46c, the shrinkage stress generated in the bottom member 43 at the time of shrinkage of the thermoplastic resin after injection molding is absorbed and dispersed by the thin portions 46a, 46b, 46c, and the shrinkage stress is generated by the side wall members 44b, 44c, 44d.
Can be prevented. Therefore, the side wall member 44
It is possible to prevent stress deformation in which the upper ends of b, 44c, and 44d in particular curve inward of the main body 42.

In the above embodiment, the joint portion 45a between the bottom member 43 and the side wall member 44a has no thin portion. This is because the lid portion 47 is connected and connected to the upper end portion of the side wall member 44a, and even if the contracting stress generated in the bottom member 43 acts on the side wall member 44a, the side wall member 44a does not move.
This is because the lid portion 47 prevents the inner portion 2 from being curved.

Further, in the example shown in FIG. 8, a recess is provided in the joint from the inside of the resin molded body 41 to form a thin portion 46.
Although a, 46b, and 46c are formed, it is not limited to this. For example, as shown in FIG. 9, thin-walled portions 46a, 46b, 46c can be obtained by forming a shape in which a part of the joint portion is shaved off from the outside of the resin molded body 41.
May be formed. When the appearance of the resin molded body is emphasized, a recess is provided in the joint from the inside of the resin molded body 41 as shown in FIG. 8 to emphasize the inner surface of the resin molded body (accurate capacity is required. Or a case where there is no liquid pool and good drainage is required, etc.), a thin portion can be formed by scraping off a part of the joint from the outside of the resin molded body 41 as shown in FIG. it can. In addition, the above recess,
The scraping portion may be provided continuously to the joint portion or may be intermittent.

In the resin molding of the present invention as described above, the thickness of the thin portion depends on the resin used, the shape of the resin molding,
It can be appropriately set in consideration of the purpose of use, required strength, etc. Usually, the thickness of the thin portion is set within a range of 20 to 60%, preferably 30 to 40% of the thickness of the other portion of the resin molded body. can do.

The resin molding of the present invention as described above is molded by injection molding using a thermoplastic resin. The thermoplastic resin used may be any thermoplastic resin conventionally used in injection molding, for example, polyethylene resin, polypropylene resin, polystyrene resin, polybutylene terephthalate resin, polyethylene terephthalate resin, polyacrylonitrile. Resin, ABS
Examples thereof include resins, polycarbonate resins, polyamide resins such as nylon, and the like. Among the above-mentioned thermoplastic resins, polyethylene resin and polypropylene resin have a large heat shrinkage rate, and the effect of the present invention is more remarkably exhibited when such a resin is used.

The resin molding of the present invention can be molded by a known injection molding method, and the molding method is not particularly limited. Then, in order to form a thin portion at the joint, whether the core side of the molding die is processed, the cavity side is processed, or both the core side and the cavity side are processed. Can be appropriately selected.

Needless to say, the resin molding of the present invention is not limited to the above-mentioned embodiment. For example,
It may be a resin molding having a part of the shape of the embodiment shown in FIGS. 1 to 6 described above. In the embodiment shown in FIGS. 7 to 9, the bottom member has a rectangular shape,
Although the number of the side wall members is four, the shape of the bottom member may be a polygon other than the rectangular shape, and the side wall member corresponding thereto may be provided.

[0027]

As described above in detail, according to the present invention, the contraction stress generated in the plate-shaped member at the time of contraction of the thermoplastic resin after injection molding causes at least a part of the joint portion with another plate-shaped member. It is absorbed and dispersed by the thin-walled portion provided in the above, whereby the stress deformation of the member is effectively prevented, and it becomes possible to obtain a highly precise resin molded body that maintains the dimensional accuracy in the design stage.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a resin molded body of the present invention.

FIG. 2 is a perspective view showing another embodiment of the resin molded body of the present invention.

FIG. 3 is a perspective view showing another embodiment of the resin molded body of the present invention.

FIG. 4 is a perspective view showing another embodiment of the resin molded body of the present invention.

FIG. 5 is a perspective view showing another embodiment of the resin molded body of the present invention.

FIG. 6 is a perspective view showing another embodiment of the resin molded body of the present invention.

FIG. 7 is a perspective view showing another embodiment of the resin molded body of the present invention.

8 is a vertical cross-sectional view taken along line VIII-VIII of the resin molded body shown in FIG.

9 is a view corresponding to FIG. 8 showing a cross-sectional shape of another embodiment of the resin molded body shown in FIG. 7.

FIG. 10 is a perspective view showing an example of a conventional resin molded body.

11 is a plan view of the resin molded body shown in FIG.

[Explanation of reference numerals] 1,11,21,31,41 ... Resin molded bodies 2a, 2b, 12a, 12b, 12c, 22a, 22
b, 22c, 32a, 32b, 32c, 32d, 43,
44a, 44b, 44c, 44d ... Plate-shaped members 3, 13, 23a, 23b, 23c, 33a, 33b,
33c, 33d, 45a, 45b, 45c, 45d ... Joining parts 4, 14, 24a, 24b, 24c, 34a, 34b,
34c, 34d, 46a, 46b, 46c ... Thin-walled portion

Claims (5)

[Claims] 1. A resin molded body comprising at least two plate-shaped members, and at least a part of a joint portion of each member having a thin portion. 2. The resin molded body according to claim 1, wherein one end of the member has a joint portion in a shape of abutting against one surface of the other member. 3. The resin molded body according to claim 1, wherein each of the three members has a joint portion in which each one end portion is in contact with each other. 4. At least three plate-shaped members are provided, and 1
The resin molded product according to claim 1, wherein an end portion of one member has a joint portion that is in contact with an end portion of another member. 5. The resin molded body according to claim 1, wherein another member stands up from a peripheral portion of one member.