JP2002036281A - Resin molding and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable manufacture by short manufacturing step in a simple mold by performing sound absorbing characteristics without laminating a sound absorbing material at a stage of forming a box or a cylinder. SOLUTION: A resin molding 1 formed in a developed shape of a box 1A comprises a plurality of integral surface forming parts 2. A method for manufacturing the resin molding 1 comprises the steps of providing a thinner folding part 3 than a thickness of the surface forming part 2 between the forming parts 2, providing a male mold locking part 5 and a female mold locking part 6 at respective sides 2d of the forming parts 2 adjacent in a state in which the parts 2 are folded at the folding part 3 to form the box 1A, and providing hollow parts 7 of the forming part 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sound-absorbing structure which is formed by bending a box or a cylinder so as to minimize the propagation of noise to buildings, automobiles, railway vehicles, ships and industrial equipment. TECHNICAL FIELD The present invention relates to a resin molded article used as a resin molding and a method for producing the same, and particularly to a resin molded article suitable for use as a sound absorbing structure for preventing noise of an automobile engine or an air intake / exhaust system from propagating into or out of a vehicle, and production thereof It is about the method.

[0002]

2. Description of the Related Art Conventionally, as the above-described sound absorbing structure, for example, there are a wall of an anechoic chamber and an engine cover of an automobile.
In automobiles that are required to improve fuel efficiency and reduce manufacturing costs, in order to reduce the weight and shorten the manufacturing process, sound-absorbing parts made of resin molded bodies are used as sound-absorbing parts in the engine room and in the car. Many are used.

In the case of a sound-absorbing part made of this resin molded body,
Due to the possibility that noise from the engine may propagate inside the vehicle and reduce quietness, a sound absorbing property is provided by attaching a resinous porous material such as urethane foam or a nonwoven fabric to part or all of the resin molded body We use after doing.

[0004]

However, the above-mentioned conventional sound-absorbing component made of a resin molded product is suitable for a relatively large use, but is used in an engine room such as an engine cover of an automobile or the like for an air cleaner. Parts and parts around the car engine, such as the intake duct,
In other words, in the case of a component that must be used in a limited space, it is difficult to design freely, and it is necessary to attach a sound absorbing material such as a resin porous body or a nonwoven fabric to the component, There are many problems, such as the fact that the attached sound absorbing material absorbs oil or moisture, thereby reducing the sound absorbing effect.

Further, since parts such as an engine cover, an air cleaner, and an intake duct of the automobile have a three-dimensional shape such as a box or a cylinder, the size of the mold is increased, and complicated mold control is required. Is required, and solving these problems has been a conventional problem.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and can exhibit sound absorbing characteristics without sticking a sound absorbing material when formed into a box or a cylinder. Moreover, it is an object of the present invention to provide a resin molded body that can be manufactured with a simple mold in a short manufacturing process and a method for manufacturing the same.

[0007]

According to a first aspect of the present invention, there is provided a resin molded body having a plurality of surface forming portions integrally provided with a box body.
(Including a box having one open side) or a resin molded body having a developed shape of a cylindrical body, and a bent portion having a thickness smaller than the thickness of the surface forming portion is provided between the surface forming portions, In a state where the surface forming portion is turned back at the bent portion to form a box or a cylinder, connecting means are provided on each side of the surface forming portion adjacent to each other, and the surface forming portion is provided with a sound absorbing means. The configuration of the resin molding is used as means for solving the conventional problems.

[0008] The resin molded article according to claim 2 of the present invention comprises:
In a state where the surface forming portion is folded back at the bent portion to form a box or a cylinder, a plurality of hollow portions which are open on the inward surface of the surface forming portion and have a depth up to near the outward surface of the surface forming portion are sound-absorbed. It is configured as a means.

[0009] The resin molded article according to claim 3 of the present invention comprises:
The inwardly facing surface of the bent portion located on the inside at the stage of forming the box or the cylinder forms the same plane as the inwardly facing surface of the surface forming portion, and the outward facing surface of the bent portion located on the outside is between the surface forming portions. The resin molded body according to claim 4 of the present invention has a configuration in which a bottom surface of a concave portion formed on the outside is formed. The end faces are arranged at an angle of 90 to 140 °, and in the resin molded article according to claim 5 of the present invention, the thickness of the bent portion is 4 times the thickness of the adjacent surface forming portion.
/ 5 or less.

In the resin molded product according to claim 6 of the present invention, the hollow portion closest to the bent portion among the plurality of hollow portions provided in the surface forming portion is arranged at a distance of 5 mm or more from the bent portion. The resin molded article according to claim 7 of the present invention has an angle of 90 to 120 ° between the outward surface of the bent portion serving as the bottom surface of the concave portion and the end surface of the surface forming portion serving as the side surface of the concave portion, The distance between the hollow portion closest to the bent portion of the plurality of hollow portions in the surface forming portion and the bent portion is 5 to 10 mm.

In the resin molded product according to the present invention, the connecting means is provided on one of the sides of the surface forming portions which are adjacent to each other in a state of being formed in a box or a cylinder. A male locking portion and a female locking portion which is provided on one of the other sides of the adjacent surface forming portion and fits and locks into the male locking portion. The resin molded article according to claim 9 of the present invention has a configuration made of a thermoplastic resin.

[0012] On the other hand, according to a method of manufacturing a resin molded product according to claim 10 of the present invention, when manufacturing the resin molded product according to any one of claims 2 to 9, one of the molds having a movable mold and a fixed mold. Filling a cavity of a molding apparatus having a mold and a mold having a gas injection nozzle for forming a hollow portion and forming a cavity between one mold with a molten resin, and during filling of the molten resin. Or pressurizing the cavity through the gas injection nozzle for forming the hollow part of the other mold while expanding the cavity volume by retracting only the movable mold while leaving the fixed mold of one mold immediately after filling the molten resin. Gas is injected to form a thick surface forming portion having a hollow portion between the movable mold of one mold and the other mold, and the fixed mold of one mold and the other mold are formed. It is configured to form a thin bent part with the mold, The structure of the method of manufacturing a resin molded body is a means for solving the conventional problems.

[0013] In the resin molded product according to the second aspect of the present invention, the hollow portion as the sound absorbing means has the mass of the air that opens at the inward surface of the surface forming portion to the vicinity of the outward surface of the surface forming portion. A vibration system having an air spring having an air gap having a depth of has a specific frequency. The natural frequency of this hollow portion can be adjusted to the frequency at which attenuation is required by controlling the diameter of the opening and the volume of the gap.

That is, when the box is formed from a resin molded body, sound absorption characteristics can be exhibited at an arbitrary frequency by controlling the diameter of the opening of the hollow portion and the volume of the gap. By providing a hollow part in the whole or a part of the box, it is possible to make the sound absorbing characteristics of the box as a sound absorbing part uniform or to be biased.
By providing hollow bodies having different aperture diameters and void volumes in the same box, it is possible to cope with a wide range of noise.

In the resin molded product according to the fourth aspect of the present invention, the reason for the above configuration is that the outward surface of the bent portion serving as the bottom surface of the concave portion and the end surface of the surface forming portion serving as the side surface of the concave portion are formed. When the angle is less than 90 °, it is difficult to form a hollow portion by expanding the cavity volume in the molding apparatus because the draft angle disappears. On the other hand, when the angle exceeds 140 °, The volume of the surface forming portion is reduced, and the number, volume and arrangement of the hollow portions are restricted, so that it is difficult to exhibit a desired sound absorbing characteristic. In addition, the rigidity of the bent portion is reduced and cracks are generated due to vibration or the like. It is preferable that, in the resin molded product according to claim 7 of the present invention, the outward surface of the bent portion serving as the bottom surface of the concave portion and the concave portion are formed. Side of It is 90 to 120 ° the angle between the surface from forming end face of the.

In the resin molded product according to the fifth aspect of the present invention, the reason for the above-mentioned configuration is that if the thickness of the bent portion exceeds 4/5 of the thickness of the adjacent surface forming portion, the bent portion is formed. This is because cracks are generated when the surface forming portion is turned back, and the durability is significantly deteriorated, or a case where the surface forming portion cannot be turned back occurs. At this time, the thickness of the bent portion becomes smaller than that of the adjacent surface forming portion. If the thickness is less than 1/5, when the box is formed, a crack is generated by vibration and the sound absorbing effect may be remarkably reduced, so that the thickness of the bent portion is reduced to 1 / th of the thickness of the adjacent surface forming portion. More preferably, it is set to 5/4/5.

In the resin molded product according to claim 6 of the present invention, if the adjacent hollow portion is too close to the bent portion,
Cracks are generated due to bending stress applied when the surface forming portion is folded, resulting in poor appearance, or insufficient strength to ensure long-term use. On the other hand, if the adjacent hollow portion is too far from the bent portion, both the number of hollow portions and the volume of the surface forming portion are reduced, and the sound absorption is reduced. Although it depends, the hollow portion closest to the bent portion of the plurality of hollow portions is arranged at a distance of 5 mm or more from the bent portion. More preferably, the bent portion is formed in the resin molded body according to claim 7 of the present invention. The distance between the hollow part adjacent to the part and the bent part is 5 to 10 mm.

In the resin molded product according to the present invention, the male locking portion and the female locking portion as the connecting means are formed in a box-shaped or cylindrical body with adjacent surface forming portions. It may be provided alternately on each side, the widest part of the male locking part is set to be larger than the widest part of the female locking part, and the female locking part is expanded using the elasticity of the resin. In the widest part,
The widest part of the male locking part is fitted and locked. In this case, a structure in which the root side is narrow and the distal end side expands stepwise or continuously may be adopted as the male locking portion. Further, the male locking portion and the female locking portion can be provided on the whole or a part of the side of the surface forming portion. When the male locking portion and the female locking portion are formed in a box or a cylinder, the male locking portion and the female locking portion can be provided. The connection strength can be further increased between the female locking portions by using a bonding method such as application of an adhesive, vibration welding, and heat compression.

In the resin molded article according to the ninth aspect of the present invention, the resin molded article is made of a thermoplastic resin which has fluidity at the time of heat molding and can be easily turned back after molding.
Examples of the thermoplastic resin include olefin resins such as polyethylene and polypropylene, acrylic resins such as acrylonitrile, polystyrene resins such as ABS and polystyrene, polyamide resins, and saturated resins such as polycarbonate, PBT, and PET. Polyester resin, fluorine resin such as polyacetal, polyethersulfone, polysulfone, polyphenylene oxide, polyphenylene sulfide, polyetherimide, aromatic polyester, and vinyl resin, and alloy containing these as one component may be used. It is preferable to use an olefin resin such as polyethylene or polypropylene or a polyamide resin. These resins include fillers such as talc, glass beads, silicon oxide, coloring pigments, metal powder, calcium carbonate, glass fibers, polyamide fibers, carbon fibers, light stabilizers, antioxidants, and fiber reinforced materials. Alternatively, various additives can be appropriately added.

Examples of the use of the sound-absorbing component made of the resin molded article according to the present invention in an automobile include an engine shielding cover, an air cleaner case, an intake air duct component, and an air conditioner air duct component. The present invention is not limited thereto, and can be widely used for parts that are formed of a resin material and have a sound insulation or sound absorption function, or a box or a cylinder that requires light weight and rigidity.

On the other hand, as an apparatus for manufacturing the resin molded article according to the present invention, an apparatus capable of easily controlling the volume of the hollow space and the diameter of the opening can be employed. In order to expand the cavity volume by expanding the cavity volume while the resin is filled during or after filling the resin, the heating device is used to exhibit the fluidity of the resin. A device that can form a hollow portion by injecting a pressure gas into the resin is desirable, for example,
An injection molding device and an injection compression molding method device are exemplified.

As shown in FIG. 3, the cavity C has, for example, another mold (B) having an opening in a hollow portion corresponding to the inward surface side of the surface forming portion when formed in a box. And one mold (A) corresponding to the outward facing side of the surface forming portion when formed on the box body, and one mold (A) is a movable mold (A) forming the surface forming portion. A1) and a fixed mold (A2) that forms a bent portion. Movable mold
The other mold (B) corresponding to (A1) is provided with a pressurized gas injection nozzle for forming a hollow portion, but the other mold (B) corresponding to the fixed mold (A2) is used for forming a hollow portion. No pressurized gas injection nozzle is provided. Then, as described above, the movable mold (A
1) Due to the retreat, the volume of the cavity C is increased to form a surface forming portion. For the retraction of the movable mold (A1), known driving means such as a hydraulic cylinder, a pneumatic cylinder, and an electric cylinder can be used. In addition, a movable mold (A1)
Receives a signal during or immediately after filling the cavity C with the molten resin, and recedes. At the same time as the movable mold (A1) is retracted, gas is injected into the cavity C from the pressurized gas injection nozzle for forming a hollow portion. .

At this time, the diameter of the opening of the hollow portion is controlled by the diameter of the pressurized gas injection nozzle for forming the hollow portion, and the diameter of the opening of the hollow portion can be easily controlled according to the required sound absorption frequency range. Also, by appropriately changing the position of the pressurized gas injection nozzle for forming the hollow portion and the distance between the nozzles, the volume of the hollow portion can be easily controlled. The mold can be provided with a function of heating the pressurized gas and a function of adjusting the gas amount and pressure according to the type of resin to be molded. Further, it is possible to provide a gas chamber in the mold to have a function of supplying a fixed amount of gas whose temperature and pressure are adjusted to each nozzle or to a plurality of nozzles.

The resin molded body manufactured by the above molding apparatus is
A box (including a box having an open side) or a tubular body having a plurality of surface forming portions integrally formed, and after being removed from the mold, the opening of the hollow portion is formed in the box. Alternatively, the surface forming portion is folded back at the bent portion while being positioned on the inward surface of the cylindrical body, and the adjacent surface forming portions are connected to each other by a connecting means formed on the surface forming portion to assemble into a box. In this case, the appearance quality may be improved by applying a sealant or the like to the bent portion or the connecting means after assembly.

[0025]

In the resin molded article according to the first aspect of the present invention, since the box or the cylindrical body is formed in an expanded shape, it is simpler and simpler than the case where a three-dimensional resin molded article is manufactured. It can be manufactured in a short period of time, and in addition, since the surface forming part is provided with sound absorbing means, at the stage of forming on the box or cylinder, the sound absorbing characteristics are fully exhibited without attaching the sound absorbing material You will get.

When the resin molded article according to the second aspect of the present invention is formed as a box covering a noise generating source, since each opening of the plurality of hollow portions is located toward the inner surface of the box, the noise is reduced. The sound that enters the hollow part from the source causes resonance in accordance with the natural frequency of the hollow part, violently vibrates, and is converted from sound energy to heat energy by friction with the voids in the hollow part and each wall of the opening. , Resulting in attenuation.

Further, since the hollow portion has a depth up to the vicinity of the outward surface of the surface forming portion, the resin layer between the adjacent hollow portions corresponds to the rib. The sandwiched resin layer will be formed in a state perpendicular to the inward or outward surface of the box,
Therefore, high rigidity can be exhibited.

Since the resin molded article according to the third aspect of the present invention has the above-described structure, when the surface forming portion is folded at the bent portion to form a box or a cylinder,
The interference between the end faces of the surface forming portions that form the concave portions adjacent to each other is avoided.

In the resin molded product according to the fourth aspect of the present invention, since the above configuration is adopted, when the cavity volume is increased in the molding device to form the hollow portion, the movable mold of the molding device moves. It will be done smoothly.

In the resin molded product according to the fifth aspect of the present invention, since the above-described structure is employed, the work of folding the surface forming portion at the bent portion when forming the box or the cylindrical body becomes easy.

In the resin molded product according to the sixth aspect of the present invention, the above-described structure ensures sufficient strength to withstand long-term use, and prevents the appearance at the bent portion without causing poor appearance due to cracks. The forming portion is turned back.

In the resin molded product according to the seventh aspect of the present invention, since the above-described configuration is employed, the movable mold of the molding device can be smoothly moved, and the sound-absorbing property and sufficient enough to withstand long-term use can be obtained. The surface forming portion is folded back at the bent portion while ensuring strength and without causing a poor appearance.

In the resin molded product according to the eighth aspect of the present invention, since the above-described structure is employed, the sides of the adjacent surface forming portions are easily and firmly connected with the surface forming portions being folded at the bent portions. Thus, it is possible to prevent the box or the cylinder formed in this way from being unfolded due to vibration or the like.

In the resin molded product according to the ninth aspect of the present invention, since the above-described configuration is employed, the heat molding and the folding process after the molding can be easily performed. On the other hand, in the method for producing a resin molded product according to claim 10 of the present invention,
Because of the above-described configuration, the production of the resin molded product according to the second to ninth aspects is performed easily and within a short period of time.

[0035]

According to the first aspect of the present invention, since the resin molded article has the above-described structure, the resin molded article can be manufactured easily and in a short period of time as compared with the case where a three-dimensional resin molded article is manufactured. In addition, at the stage of forming into a box or a cylinder, a very excellent effect that sufficient sound absorbing characteristics can be secured without attaching a sound absorbing material is provided.

In the resin molded article according to the second aspect of the present invention, when formed as a box covering a noise generation source, noise can be efficiently attenuated by converting noise from sound energy to heat energy in the hollow portion. It is possible, and in addition, by making the resin layer between the adjacent hollow portions function as a rib, a very excellent effect that high rigidity can be obtained is obtained.

In the resin molded body according to the third aspect of the present invention, since the resin molded body has the above-described structure, it is possible to fold the surface forming portion at the bent portion without any trouble when forming the box or the cylindrical body. Since the resin molded article according to claim 4 of the present invention has the above-described configuration,
In the molding stage by the molding device, a very excellent effect that the movable mold can be moved smoothly is provided.

In the resin molded article according to the fifth aspect of the present invention, since the above-described structure is employed, when forming the box-shaped body or the cylindrical body, the folding operation of the surface forming portion at the bent portion can be easily performed. Claims 6 and 7 of the present invention
Since the resin molded body according to the present invention has the above-described configuration, it has sufficient strength to withstand long-term use. In particular, the resin molded body according to claim 7 of the present invention has excellent sound absorbing properties and long-term use. It is possible to obtain a very excellent effect that it is possible to turn over the surface forming portion at the bent portion without causing cracks while securing sufficient strength to withstand the cracks.

In the resin molded product according to the eighth aspect of the present invention, since the above-mentioned configuration is employed, the sides of the adjacent surface forming portions can be easily formed while the surface forming portions are folded back at the bent portions, and the vibrations and the like can be easily achieved. In the resin molded article according to claim 9 of the present invention, it is possible to strongly connect without separating the resin molded body,
A very excellent effect that the heat forming and the folding process after the forming can be easily performed is provided.

On the other hand, in the method for producing a resin molded product according to claim 10 of the present invention, the above-described structure is employed.
A very excellent effect that the resin molded article according to 9 can be produced very easily and in a short time is obtained.

[0041]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

<Embodiment 1> FIGS. 1 to 4 show one embodiment of a resin molded body according to the present invention. As shown in FIG. 1A, the resin molded body 1 is integrally formed with five surface forming portions 2 to form a developed shape of a box, and between the surface forming portions 2, As shown in FIG. 1B, a bent portion 3 having a smaller thickness than the thickness of the surface forming portion 2 is provided.
As shown in (c), the inward surface 3a of the bent portion 3 located on the inside at the stage of forming the box 1A having one open surface forms the same plane as the inward surface 2a of the surface forming portion 2, while The outward surface 3b of the bent portion 3 located on the outside is the bottom surface of the concave portion 4 formed outside between the surface forming portions 2 and 2.

Further, in a state where the surface forming portion 2 is folded back at the bending portion 3 to form the box 1A, as shown in FIG. 2, each side 2d, 2d of the surface forming portions 2, 2 adjacent to each other, as shown in FIG.
The right side 2d is provided with a plurality of male locking portions (connecting means) 5 having a thinner base and a gradually expanding front end, and a male side is provided on the left side 2d. A plurality of female locking portions (connecting means) 6 having a widest portion 6a smaller than the widest portion 5a of the die locking portion 5 are provided, and the female locking portion expanded by utilizing the elasticity of the resin. 6, the widest portions 6a of the male-type locking portions 5 are fitted into the widest portions 6a of the male-type locking portions 6 and are locked to each other.
d and 2d are connected to each other.

Further, the surface forming portion 2 has a plurality of openings which are opened on the inward surface 2a of the surface forming portion 2 and have a depth up to the vicinity of the outward surface 2b of the surface forming portion 2 when they are formed on the box 1A. A hollow portion (sound absorbing means) 7 is provided.

In manufacturing the resin molded body 1,
As shown in FIG. 3, the injection molding apparatus 50 with a mold drawing pressure of 220 t is used. In the mold, 150 ×
An integrated flat body composed of one surface of 150 mm and four surfaces of 150 × 80 mm is used. In this case, the pressurized gas injection nozzle 51 for forming a hollow portion is disposed on the other stationary mold B that forms a surface corresponding to the inward surface 2a of the surface forming portion 2 when formed on the box 1A. A mold A, which is a combination of a fixed mold A2 and a movable mold A1, is used for a surface corresponding to the outward surface 2b of the surface forming portion 2 when formed on the box 1A, and a male mold is used. Locking part 5 and female locking part 6,
In addition, the surface forming portion 2 having the hollow portion 7 has a movable mold A
1 and a fixed mold A2 having a width of 10 mm is arranged in the bent portion 3.

As the gas injection nozzle 51 for forming the hollow portion, a nozzle having a diameter of 10 mm was used.
Are arranged from the center of the surface at an interval of approximately 30 mm, and four are arranged on each side of the surface at a predetermined distance from the side of the bent portion 3. Also 150 × 80mm
Eight are arranged on each side of the surface, and four are arranged near the bent portion 3 at a predetermined distance.

The fixed mold A2 adjacent to the movable mold A1 has a bent portion 3 of the resin molded body 1 as shown in FIG.
The side surface A2 of the end surface 2c of the surface forming portion 2 can be set to 90 °, 120 °, or 160 ° with respect to the bottom surface of the concave portion 4 composed of
a is inclined. Also, the thickness of the cavity C before molding can be varied from 1 to 10 mm,
Locking portion forming grooves (not shown) for forming the male locking portion 5 and the female locking portion 6 are provided at two positions of the movable mold A1.

The reference numeral 52 in FIG.
Reference numeral 53 denotes a gas chamber, reference numeral 54 denotes a resin inlet, reference numeral 55 denotes a pressurized gas supply source, reference numeral 56 denotes a pressure regulating valve, reference numeral 57
Is a control valve, and 58 is a heating device.

Then, the above injection molding device 50
Using polypropylene (PP) resin (manufactured by Nippon Polychem, trade name Novatec) as the thermoplastic material, the molten resin temperature is 19
Injection molding at 0 ° C., 5 surface forming portions 2 having hollow portions 7
Were integrally provided to obtain a resin molded article 1 having a flat plate shape.

At this time, the mold was heated to 50 ° C.
Air was used as the pressurized gas, and the air was heated to 200 ° C. and injected into the resin to form the hollow portion 7.

Further, since the side surface angle of the side surface A2a of the front end portion of the fixed mold A2 is 120 ° with respect to the front end of the fixed mold A2 facing the cavity C, the angle of the bent portion 3 serving as the bottom surface of the concave portion 4 is used. The angle formed between the outward surface 3b and the end surface 2c of the surface forming portion 2 which is the side surface of the concave portion 4 is 120 °.

Further, the thickness of the cavity C before molding is set to 4
mm, and immediately after filling the cavity C with the molten polypropylene resin, the movable mold A1 was retracted so that the thickness of the surface forming portion 2 was adjusted to 10 mm. That is, the thickness of the bent portion 3 is 4 mm, which is ／ of the thickness of the adjacent surface forming portion 2.

Further, the molded article is 150 × 150 mm
The movable mold A1 corresponding to the surface is provided with a pressurized gas injection nozzle 51 closest to the bent portion 3 at a position 10 mm away from the nearest end of the bent portion 3, and an 80 × 15
The movable mold A1 corresponding to the 0 mm surface also has the bent portion 3
The pressurized gas injection nozzle 51 closest to the bent part 3
The distance between the hollow portion 7 and the nearest end of the bent portion 3 was 8 mm.

Then, the surface forming portion 2 is folded back at the bending portion 3 such that the opening of the hollow portion 7 is positioned on the inward surface 2a of the box 1A, and the male member provided in the surface forming portion 2 is formed. By locking the mold locking portion 5 and the female locking portion 6 to each other, the adjacent surface forming portions 2 are connected to each other and assembled into a box 1A. With respect to the resin molded bodies according to the other Examples 2 to 6 shown below, the noise reduction amount, the crack in the bent portion after bending, and the crack in the hollow portion closest to the bent portion were evaluated. The results shown in Table 1 were obtained.

At this time, the noise reduction, the crack in the bent portion after bending, and the crack in the hollow portion closest to the bent portion were also evaluated for the resin molded articles according to Comparative Examples 1 to 6 shown below. Then, the results shown in Table 2 were obtained. The distance between the hollow portion and the bent portion closest to the bent portion was measured by cutting the resin molded body 1 after molding.

[Noise Reduction Amount] After assembling the box, the sound source is arranged inside the box, and a microphone is placed outside the box to measure the noise amount between the case without the box and the case with the sample. The reduction was evaluated.

The sound source is set at a center point of the above-mentioned surface 50 mm away from the 150 × 150 mm plane of the box, and the microphone is set at a position 100 mm away from the center point outside the same plane.
The average value evaluated five times at a measurement frequency of 1 to 2 KHz was used. The reduced sound is a value measured in a 1/3 octave band.

Noise reduction amount (dB) = (no test sample) − (test sample present) [Crack at bent portion after bending] After bending the resin molded product of the test sample and assembling it into a box The four bent portions were evaluated visually and with an optical microscope. ：: No crack (no cracks in 10 boxes) ×: Cracks (1 or more cracks in 10 boxes) [Crack in hollow portion closest to bent portion] Resin molding of test sample After bending the body and assembling it into a box, the surface forming portion adjacent to the bent portion was immersed in a fluorescent test solution, and the presence or absence of cracks in the hollow portion closest to the bent portion was visually and optically evaluated. ○: No crack (no cracks in 5 boxes) ×: Cracks (1 or more cracks in 5 boxes)

Example 2 A resin molded article was prepared under the same conditions as in Example 1 except that the thickness of the cavity C before molding was 7 mm, and the molded article was taken out and assembled into a box for evaluation.

Example 3 A resin molded article was prepared under the same conditions as in Example 1 except that the thickness of the cavity C before molding was 3 mm, and the molded article was taken out and assembled into a box for evaluation.

<Embodiment 4> Tip side A of fixed mold A2
A resin molded body was prepared under the same conditions as in Example 1 except that the angle of 2a was 135 °, and the molded body was taken out, assembled into a box, and evaluated.

<Embodiment 5> Side A of the front end of the fixed mold A2
A resin molded body was prepared under the same conditions as in Example 1 except that the angle of 2a was 90 °, and the molded body was taken out, assembled into a box, and evaluated.

<Embodiment 6> The pressurized gas injection nozzle closest to the bent portion is set 13 mm from the end closest to the bent portion.
And the distance between the hollow part and the nearest end of the bent part is 10 m.
A resin molded body was prepared under the same conditions as in Example 1 except that m was set, and the molded body was taken out, assembled into a box, and evaluated.

[0064]

[Table 1]

Comparative Example 1 A resin molded body was prepared under the same conditions as in Example 1 except that the gas injection from the pressurized gas injection nozzle was stopped and the resin was filled even after the movable mold A1 was retracted. The molded body was taken out, assembled into a box, and evaluated.

<Comparative Example 2> After a resin molded article was prepared under the same conditions as in Comparative Example 1, 10
After attaching a nonwoven fabric having a thickness of mm to the surface forming portion, the molded body was assembled into a box and evaluated.

<Comparative Example 3> The thickness of the bent portion was 10 mm.
A resin molded body was prepared under the same conditions as in Example 1 except that the molded body was prepared, and the molded body was taken out, assembled into a box, and evaluated.

Comparative Example 4 A resin molded article was prepared under the same conditions as in Example 1 except that the thickness of the bent portion was 1 mm, and the molded article was taken out and assembled into a box for evaluation.

<Comparative Example 5> Side A of the Tip of Fixed Mold A2
A resin molded body was prepared under the same conditions as in Example 1 except that the angle of 2a was changed to 160 °, and the molded body was taken out, assembled into a box, and evaluated.

COMPARATIVE EXAMPLE 6 A pressurized gas injection nozzle closest to the bent portion was provided 3 mm from the nearest end of the bent portion, and the distance between the hollow portion and the closest end of the bent portion was set to 1 mm. A resin molded body was prepared under the same conditions as in Example 1, and the molded body was taken out, assembled into a box, and evaluated.

[0071]

[Table 2]

From the results shown in Tables 1 and 2, Comparative Example 1
It was demonstrated that the resin molded products of Examples 1 to 6 based on the present invention had excellent sound absorbing performance and strength that can withstand long-term use, as compared with the resin molded products of Comparative Examples 1 to 6.

In the above-described embodiment, the case where the resin molded article 1 according to the present invention has a developed shape of a box having one open side has been described. However, the present invention is not limited to this. For example, as shown in FIG. 5, the resin molded body has a developed shape of a box in which all surfaces are closed, or FIG.
As shown in (1), the resin molded body may have a developed shape of a cylindrical body.

Further, in the above-described embodiment, the case where the connecting means is the male locking portion 5 and the female locking portion 6 has been described.
However, the present invention is not limited to this. The male locking portion 5 and the female locking portion 6 as connecting means are alternately formed on the sides of the adjacent surface forming portions in a state of being formed in a box or a cylinder. They may be provided side by side.

Further, as shown in FIG. 7, the male locking part 5 has a male locking part 15 having a structure in which the root side is thin and the tip side is continuously enlarged, and a female locking part 16 corresponding thereto. In addition, as shown in FIG. 8, a male locking portion 25 and a female locking portion 26 can be provided on the entire side of the surface forming portion 2.

The detailed structure of the resin molded product and the method of manufacturing the same according to the present invention is not limited to the above-described embodiment.

[Brief description of the drawings]

FIG. 1 is an explanatory plan view showing one embodiment of a resin molded body according to the present invention, FIG. 1 (b) is a cross-sectional explanatory view based on the position of line II, and FIG. ).

FIG. 2 is an enlarged perspective explanatory view showing a male locking portion and a female locking portion as connecting means of the resin molded body in FIG.

3A and 3B are an explanatory cross-sectional view before a resin filling and an explanatory cross-sectional view after a resin filling of an injection molding machine used for manufacturing the resin molded article of FIG. 1;

FIG. 4 is an enlarged sectional explanatory view of one mold in FIG. 3 (a).
Sectional explanatory view of one mold in (a) and FIG. 3 (b)
(b).

FIG. 5 is an explanatory plan view showing another embodiment of the resin molded product according to the present invention, and FIG. 5 is an explanatory cross-sectional view taken along the line II-II.
It is a perspective explanatory view (c) of the state assembled in (b) and a box.

FIG. 6 is a plan view (a) showing still another embodiment of the resin molded body according to the present invention, and a perspective view (b) of a state where the resin molded body is assembled into a cylindrical body.

FIG. 7 is an enlarged perspective explanatory view showing another configuration example of the connecting means.

FIG. 8 is an enlarged perspective explanatory view showing still another configuration example of the connecting means.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 resin molded body 2 surface forming portion 3 bent portion 4 concave portion 5 male locking portion (connecting device) 6 female locking portion (connecting device) 7 hollow portion (sound absorbing device) 2a inward surface of surface forming portion 2b surface Outward surface of forming portion 2c End surface of surface forming portion 2d Side of surface forming portion 3a Inward surface of bent portion 3b Outward surface of bent portion 50 Molding device 51 Gas injection nozzle for forming hollow portion A One mold A1 Movable Mold A2 Fixed mold B The other mold C Cavity

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G10K 11/16 B29K 101: 12 // B29K 101: 12 105: 04 105: 04 B29L 31:00 B29L 31: 00 G10K 11/16 GCF term (Reference) 2E001 DF04 GA20 HD11 3D023 BA03 BB21 BB30 BD11 BE03 BE04 BE31 4F202 AG07 AG20 AG30 AH26 AH56 CA11 CB01 CK25 4F206 AG07 AG20 AG30 AH26 AH56 JA04 JC01 JN27 JN13 A06

Claims (10)

[Claims] 1. A resin molded body integrally provided with a plurality of surface forming portions and having a box-shaped or cylinder-shaped developed shape, wherein the thickness of the wall between the surface forming portions is smaller than the thickness of the surface forming portions. In addition to providing the bent portion, the surface forming portion is folded at the bent portion to form a box or a cylinder, and connection means are provided on each side of the adjacent surface forming portion in a state where the surface forming portion is adjacent to each other, and the surface forming portion is provided with sound absorbing means. A resin molded article characterized by the following. 2. A plurality of hollow portions, which are formed in a box or a cylinder and open on the inward surface of the surface forming portion and have a depth up to near the outward surface of the surface forming portion, are used as sound absorbing means. Item 7. The resin molded article according to Item 1. 3. The inwardly facing surface of the bent portion located inside when formed into a box or a cylinder is flush with the inwardly facing surface of the surface forming portion, and the outwardly facing surface of the bent portion located outward is The resin molded product according to claim 1 or 2, which serves as a bottom surface of a concave portion formed outside between the surface forming portions. 4. An end face of a surface forming portion, which is a side surface of the concave portion, of 90 to 1 with respect to an outward surface of a bent portion which is a bottom surface of the concave portion.
The resin molded product according to claim 3, which is arranged at an angle of 40 °. 5. The resin molded product according to claim 1, wherein the thickness of the bent portion is 4/5 or less of the thickness of the adjacent surface forming portion. 6. A hollow portion closest to a bent portion among a plurality of hollow portions provided in the surface forming portion, the hollow portion located 5 mm away from the bent portion.
The resin molded product according to any one of claims 2 to 5, which is arranged at a distance of at least mm. 7. The angle between the outward surface of the bent portion serving as the bottom surface of the concave portion and the end surface of the surface forming portion serving as the side surface of the concave portion is set to 9 degrees.
The resin molded product according to claim 6, wherein the distance is 0 to 120 °, and the distance between the bent portion and the hollow portion closest to the bent portion among the plurality of hollow portions in the surface forming portion is 5 to 10 mm. 8. A connecting means comprising: a male locking portion provided on one of sides of a surface forming portion adjacent to each other in a state of being formed in a box or a cylinder; 8. The female locking portion according to claim 1, further comprising a female locking portion provided on one of the other sides of the forming portion and fitted into and locking with the male locking portion. Resin molding. 9. The resin molded article according to claim 1, which is made of a thermoplastic resin. 10. A method for manufacturing the resin molded product according to claim 2, wherein one of the molds includes a movable mold and a fixed mold, and one of the molds includes a gas injection nozzle for forming a hollow portion. Filling the cavity of the molding apparatus with the other mold that forms a cavity with the mold with molten resin, and fixing the fixed mold of one mold during or immediately after filling with the molten resin. While retracting only the movable mold and increasing the cavity volume, pressurized gas is injected into the cavity through the cavity-forming gas injection nozzle of the other mold, and the movable mold of one mold and the other Forming a thick surface forming portion having a hollow portion with the mold, and forming a thin bent portion between the fixed mold of one mold and the other mold. Manufacturing method of a molded resin article.