JP2022133446A - Sound absorbing panel material for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sound absorbing panel material for a vehicle and its manufacturing method, in which the panel material itself has a sound absorbing function without a need to attach a sound absorbing material consisting of separate components, thereby reducing weight and cost, and enabling sound absorption not only of noise from outside the vehicle but also of noise entering the vehicle cabin.

SOLUTION: A sound absorbing panel material for a vehicle includes: a sound absorbing panel part 8 in which a porous sheet with a through hole is formed by maintaining a multicellular structure; and a synthetic resin molded part 7 that is integrally molded with the sound absorbing panel part and includes a frame part 75 that surrounds the sound absorbing panel part and a frame part 77 that connects to the frame part inside the frame part. The through hole is blocked by the synthetic resin molded part.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2022,JPO&INPIT

Description

TECHNICAL FIELD The present invention relates to a vehicle sound absorbing panel material having a sound absorbing effect and a manufacturing method thereof, and more particularly to a vehicle sound absorbing panel material suitable for an undercover of an instrument panel, an engine undercover, etc., and a manufacturing method thereof.

Vehicles such as automobiles have panel materials such as engine undercovers and instrument panel undercovers, to which sound absorbing materials are attached. Sound absorption can be imparted by attaching a sound absorbing material, and several improvement inventions have been proposed (for example, Patent Document 1).

JP 2017-115641 A

However, the invention of Patent Document 1 is an invention in which the first protective member and the second protective member are brought into contact with each other in order to solve the problem that the sound absorbing members come into contact with each other due to the vibration of the running vehicle and wear out. It was an invention that added a separate sound absorbing material to the panel material. It was limited to the invention of a panel material with a sound absorbing material that put together two separate parts, an undercover and a sound absorbing material. Further, the conventional product will be described with a panel material 9 with a sound absorbing material of an undercover related to an instrument panel shown in FIG. ing. Although it can absorb external noise that tries to enter the vehicle interior, it cannot absorb sound that leaks into the vehicle interior through gaps. The sound leaking into the passenger compartment bounces off and hits the panel material surface 91a on the passenger compartment side shown in FIG. I had a problem.

The present invention solves the above-mentioned problems by eliminating the mounting of a separate sound-absorbing material, and imparting a sound-absorbing function to the panel material itself to achieve weight reduction and cost reduction, and further reduce noise from outside the vehicle. To provide a sound absorbing panel material for a vehicle capable of absorbing not only the noise but also the noise entering into the vehicle interior, and a method for manufacturing the same.

In order to achieve the above object, the gist of the first invention is that a pin protrudes from a cavity surface for setting a sheet of a desired size in one mold, and the sheet is arranged by clamping with the other mold. The cavity portion of the frame portion is formed together with the cavity portion of the frame portion that surrounds the cavity portion of the synthetic resin frame, and the position of the pin is arranged in the region of the cavity portion related to the frame portion or the beam. Using an injection molding machine equipped with a mold consisting of a pair of molds provided with recesses for covering the pins, the sheet is made into a porous sheet, and the porous sheet is inserted into the pins and set. Next, the mold is clamped to form a sound absorbing panel portion that maintains a porous structure, and together with the molding of the frame portion and the crosspiece that retains and integrates the sound absorbing panel portion, the concave portion A method of manufacturing a sound absorbing panel material for a vehicle, characterized in that a bottomed cylindrical boss portion having a loophole through which the pin is removed is formed in the formed cavity portion. A method for manufacturing a sound absorbing panel material for a vehicle according to a second invention is the first invention, wherein a plurality of the pins are spaced apart and protrude from the cavity surface in which the sheet is set in one of the molds, and the pins are are arranged in the region of the cavity portion related to the frame or the crosspiece, and the other mold is provided with recesses for covering the pins. A third aspect of the invention is a method for manufacturing a sound absorbing panel material for a vehicle, which is characterized in that the porous sheet is a nonwoven fabric in the first or second aspect of the invention. A method for manufacturing a sound absorbing panel material for a vehicle, which is a fourth invention, is the first to third inventions, wherein the framing crosspieces of the frame are formed in a lattice shape, and the plurality of pins are provided by the mold clamping. It is characterized in that the position is arranged in the area of the cavity portion related to the intersection of the crosspieces formed in a grid pattern. A fifth invention is a method for manufacturing a sound absorbing panel material for a vehicle according to the first to fourth inventions, wherein the porous sheet is made of a nonwoven fabric in which a low melting point material and a high melting point material are mixed, and after heating the porous sheet , and set in one of the molds by inserting them into the pins. A sixth aspect of the invention is a method for manufacturing a sound absorbing panel material for a vehicle according to any one of the first to fifth aspects of the invention, wherein a through hole having a diameter smaller than the cross-sectional diameter of the base of the pin is provided at a point of the porous sheet into which the pin is inserted. and setting the porous sheet by inserting the pin into the through hole. The gist of the seventh invention is a sound absorbing panel part in which a porous sheet having a plurality of through holes is shaped while maintaining a porous structure, and the through holes are three-dimensionalized as through hole corresponding parts. a synthetic resin molded portion surrounding and framing the sound absorbing panel portion to retain the shape of the sound absorbing panel portion and comprising a frame and a crosspiece integrally molded therewith; and the synthetic resin molding portion. Of the frame or crosspiece that is a part and integrated with the back surface of the sound absorbing panel portion, in the region where the through hole corresponding portion exists, the hole is aligned with the through hole corresponding portion, and the loop hole is provided. A boss portion provided in a cylindrical shape with a bottom.

As in the first invention, when the mold is clamped to form a sound absorbing panel portion that maintains a porous structure, and the frame portion and the crosspiece that retain and integrate this shape are formed, the sound absorbing panel portion is formed. The required sound absorption performance can be provided, and the insufficient rigidity can be borne by the frame and crosspieces. If a pin is used, there is the problem of a hole being left on the product as a trace of the pin. There is no need for a post-process to close the pin trace hole. As in the second invention, when a plurality of the pins are spaced apart from each other and protrude, the two-dimensional movement of the porous sheet on the cavity surface is stopped by inserting each pin into the through hole of the porous sheet. Therefore, the porous sheet can be positioned and set in the mold without difficulty. In addition, if the sound absorbing panel portion is cut to the size in advance, the trimming cut of the sound absorbing panel portion from the three-dimensional product after demolding can be eliminated.

In the sound absorbing panel material for a vehicle and the method for manufacturing the same according to the present invention, the sound absorbing panel portion of the main body is made to have a porous structure to maintain the sound absorbing performance. By complementing it, it is not necessary to install a separate sound absorbing material, realizing weight reduction and cost reduction. In addition, since the surface side of the sound absorbing panel also has a porous structure, it is possible to absorb not only noise from outside the vehicle but also noise that enters the vehicle interior. Furthermore, since the hole into which the pin is inserted is closed by forming the bottomed cylindrical boss, the desired sound absorbing performance can be secured without post-processing.

1 is a perspective view of a sound-absorbing panel material viewed from the back side, in one embodiment of the sound-absorbing panel material and the manufacturing method thereof of the present invention. FIG. It is the perspective view which looked at the sound-absorbing panel material of FIG. 1 from the surface side. FIG. 3 is a cross-sectional view of a main part of an injection molding machine for molding the sound absorbing panel material of FIGS. 1 and 2; 4 is an explanatory cross-sectional view of the mold of FIG. 3 in a mold open state; FIG. FIG. 5 is an explanatory cross-sectional view in which a porous sheet is set in the stationary mold of FIG. 4; FIG. 2 is a mold closing cross-sectional view corresponding to the cross-sectional view taken along the line VI-VI of FIG. 1; FIG. 2 is a mold closing cross-sectional view corresponding to the cross-sectional view taken along the line VII-VII of FIG. 1; FIG. 8 is an explanatory cross-sectional view showing injection of a synthetic resin raw material for injection molding after closing the mold in FIG. 7 and completion of injection molding; FIG. 9 is a partially broken perspective view of the periphery of the pin of FIG. 8; (A) is a plan view around the through hole, (B) is an explanatory sectional view around the through hole (A) at the time of injection molding, and (C) and (D) are alternatives to (A) and (B). It is a mode figure. 1. It is an explanatory perspective view of another aspect in place of FIG. FIG. 3 is an explanatory perspective view of another aspect in place of FIG. 2; 1 is an explanatory perspective view of a conventional technique; FIG.

Hereinafter, a sound absorbing panel material for a vehicle (hereinafter also simply referred to as a "sound absorbing panel material") according to the present invention and a method for manufacturing the same will be described in detail. 1 to 12 show an embodiment of a sound absorbing panel material and a manufacturing method thereof according to the present invention. FIG. 1 is a back side perspective view of the sound absorbing panel material, FIG. 2 is a front side perspective view of the sound absorbing panel material, and FIG. 3 is FIG. FIG. 4 is an explanatory cross-sectional view in which the mold is opened, FIG. 5 is a cross-sectional view in which a porous sheet is set in a fixed mold, and FIGS. Figure 8 is a cross-sectional view after the mold is closed, the synthetic resin raw material is injected after the mold is closed, and injection molding is completed. Figure 9 is an enlarged view around the pin in Figure 8. FIG. 2 is a plan view, (b) is a cross-sectional view around the through hole of (a) at the time of injection molding, and (c) and (d) are different views. FIGS. 11 and 12 show other modes in place of FIGS. 1-10. In order to make each drawing easy to understand, the drawings are simplified and the main part of the invention is emphasized.

(1) Manufacturing method of sound absorbing panel material for vehicle The sound absorbing panel material for vehicle 6 consists of a sound absorbing panel part 8 formed by three-dimensionally forming the porous sheet 5 and holding it with a frame part 75 made of a synthetic resin molded part 7 and a crosspiece 77. It is a product for vehicles such as automobiles that are shaped. The sound absorbing panel material 6 of this embodiment is applied to the undercover of the instrument panel shown in FIGS. The manufacturing method uses an injection molding machine 1 having a mold 2 as shown in FIG. After the preheated porous sheet 5 is set in one mold (fixed mold in this embodiment) 3, the mold is clamped to form the porous sheet 5 into the sound absorbing panel portion 8, and the sound absorbing panel portion is formed. The sound absorbing panel member 6 is manufactured by injection molding a frame portion 75 and a crosspiece 77 that hold and integrate the shape of the sound absorbing panel member 8 .

Prior to the method of manufacturing the sound absorbing panel material, an injection molding machine 1 having a mold 2 for sound absorbing panel material is prepared (Fig. 3). In the mold 2 of the injection molding machine 1, a tapered pin 31 protrudes toward the tip from the cavity surface 33 of the fixed mold 3, in which a sheet of the required size (desired size) as the sound absorbing panel portion 8 is set. . By clamping with the other mold (movable mold in this embodiment) 4, a cavity C of the sound absorbing panel material 6 is formed, and the cavity C5 of the synthetic resin frame 75 surrounding the cavity C3 in which the sheet is arranged is formed along with the cavity C5. A cavity portion C7 of the frame crosspiece 77 is formed. Cavity portion C7 communicates with cavity portion C5 at both ends thereof. The cavity portion C7 of the framework band plate-like crosspiece 77 is dug into the cavity surface on the movable mold side of the cavity portion C3 where the sheet is arranged, in a groove shape in which the band width direction is raised. are formed to intersect in a grid pattern on the movable mold side cavity surface of the cavity portion C3. A cavity portion C3 in which the sheet is arranged has a thickness smaller than that of the sheet before being set in the mold and is three-dimensional, and has a hollow shape of the sound absorbing panel portion 8 . In this embodiment, the position of the pin 31 is arranged in the region of the cavity portions C5 and C7 related to the frame portion 75 or the crosspiece 77, and the movable mold 4 is provided with an inverted cup-shaped concave portion that covers the pin 31, as shown in FIG. It is assumed that the mold 2 is provided with the place 41 . A plurality of pins 31 protrude apart from each other on the cavity surface 33 on which the sheet is set so that the sheet can be positioned and set on the stationary mold 3 . Each position of the pin 31 is arranged in the region of the cavity portions C5 and C7 related to the frame portion 75 or the crosspiece 77, and the movable mold 4 is provided with a recess 41 for covering each pin 31. As shown in FIG. In FIG. 3, reference numeral 11 denotes a nozzle of the injection molding machine 1 connected to the mold 2, reference numeral 21 denotes a gate, reference numeral 22 denotes a runner, and reference numeral 23 denotes a sprue. A porous sheet 5 is used as the sheet in the present invention.

The porous sheet 5 is a sheet-like body having a sound-absorbing porous structure such as nonwoven fabric or foam. The "sheet" of the porous sheet 5 also includes a plate-like one. The porous sheet 5 according to the present invention maintains its sound-absorbing porous structure even when the initial thickness t1 is compressed to the gap width ε of the cavity portion C3 (FIGS. 3 and 4). For the porous sheet 5, for example, a two-component composite nonwoven fabric in which a low-melting point material and a high-melting point material are mixed is used. There is a nonwoven fabric having a sheath-core structure in which each fiber has a core made of a high-melting-point material and a sheath made of a low-melting-point material, and this embodiment adopts this. After the porous sheet 5 made of the nonwoven fabric is heated to soften the sheath, it is set in the mold 2 and clamped. The sheath at the heating temperature is thermally bonded, and the core is shaped into a predetermined shape. can.

The sound absorbing panel material 6 is manufactured using the injection molding machine 1 and the porous sheet 5, for example, as follows. First, while the mold 2 is open (FIG. 4), the porous sheet 5 is heated to a predetermined temperature to be softened, and then inserted into the pins 31 to soften the surface of the porous sheet 5 on the fixed mold 3. Set on the side cavity face 33 (Fig. 5). The porous sheet 5 is cut in advance to a size corresponding to the sound absorbing panel portion 8 . When the porous sheet 5 is set on the cavity surface 33 of the stationary mold 3 , the porous sheet 5 at the sheet point corresponding to each pin 31 is provided with through holes 50 in advance. A pin 31 is inserted into the through hole 50 and the porous sheet 5 is set in the stationary mold 3 . Here, two (plurality) of pins 31 are spaced apart, and their positions are the cavity portions C7 of the crosspieces 77, and each pin is located in the region of the cavity portion related to the crossing portion 77CR of the crosspieces 77 formed in a grid pattern. 31 is arranged. When each pin 31 is inserted into the through hole 50 of the porous sheet 5 and brought into contact with the fixed mold 3 , the porous sheet 5 is autonomously positioned and held, and positioned and set on the fixed mold 3 .

Next, the mold is clamped to shape the porous sheet 5 into the sound absorbing panel portion 8, and the recesses 41 are formed together with the molding of the frame portion 75 and the crosspiece 77 that retain and integrate the shape. In the cavity portion C1, a bottomed tubular boss portion 73 having a loophole 731 through which the pin 31 is removed is molded (FIGS. 6 to 8). As the molds are clamped, the back side cavity surface 43 of the porous sheet associated with the movable mold 4 and the front surface side cavity surface 33 of the porous sheet associated with the fixed mold 3 are separated from each other, as shown in FIG. The porous sheet 5 is sandwiched between and compressed. The porous sheet 5 with the initial thickness t1 is compressed in the thickness direction while leaving the porous structure for sound absorption, and the whole is changed to approximately the thickness t2 to be shaped into a three-dimensional sound absorbing panel portion 8 . The porous sheet 5 here is a non-woven fabric having a basis weight in the range of 700 g/m ² to 1,600 g/m ² . When PET is used for the core portion of the nonwoven fabric of the core-sheath structure fiber, the sound absorbing panel portion 8 is excellent in maintaining its shape with less fatigue. When the flat nonwoven fabric is heated, the sheath portion has heat-sealing properties, and while the entire thickness changes to t2, the core portion deforms into the three-dimensional shape of the cavity C3, thereby forming a sound-absorbing porous structure. It is shaped into a retained sound absorbing panel portion 8 . If a non-woven fabric using a fiber with a core-sheath structure in which a low-melting-point PET sheath is arranged in a high-melting-point PET core is used, the sound-absorbing panel portion 8 becomes even less sag-like, and this embodiment also uses this. adopt.

In the present invention, a porous sheet 5 having a sound absorbing function is used, and the porous sheet is compressed to form a three-dimensional shape having an upper surface 88 and a lower surface 89 with a slope 87 interposed therebetween, as shown in FIG. In addition, the sound absorbing panel portion 8 is made to retain the sound absorbing function. However, even if the sound absorbing panel portion 8 is increased in strength by being compressed from the thickness t1 to the thickness t2 (FIGS. 4 to 7), it is difficult to say that the three-dimensional shape maintaining the sound absorbing porous structure is robust. Even if a PET nonwoven fabric with a three-dimensional network structure, which does not give a feeling of fatigue, is used, the rigidity and mechanical strength required for the sound absorbing panel material 6 are insufficient.

In order to solve such a lack of strength, in this manufacturing method, along with shaping the sound absorbing panel portion 8, under the mold clamping state, the cavity C is formed from the nozzle 11 of the injection molding machine 1 through the runner 22 and the gate 21. A synthetic resin raw material g (hereinafter also simply referred to as "resin raw material") is injected into the sound absorbing panel portion 8, and the frame portion 75 and crosspiece 77 for retaining the shape of the sound absorbing panel portion 8 are integrally molded with the sound absorbing panel portion 8 (Fig. 8). . A resin raw material g is injected into the cavity C to form the synthetic resin molding portion 7, and the frame portion 75 is formed in the cavity portion C5 surrounding the sound absorbing panel portion 8, and runs vertically and horizontally on the back surface 8b of the sound absorbing panel portion 8. A crosspiece 77 is molded in the cavity C7. The frame portion 75 and crosspiece 77 of the synthetic resin molded portion 7 bear the rigidity and mechanical strength that the sound absorbing panel portion 8 lacks. A raw material such as a polypropylene resin is used as the resin raw material g.

Together with a frame portion 75 that surrounds and reinforces the sound absorbing panel portion 8, a crosspiece 77 that is disposed in the frame portion 75 and whose both ends are connected to the frame portion is integrally connected to and reinforces the sound absorbing panel portion 8. - 特許庁In FIG. 8, the frame portion 75 surrounding the outer periphery of the sound absorbing panel portion 8 has an inner flange portion 75b that protrudes toward the sound absorbing panel portion 8 in an L-shaped cross section from a frame portion main body 75a that stands up against the sound absorbing panel portion 8. During the molding process of the inner flange portion 75b, the resin raw material g is impregnated into the sound absorbing panel portion 8 and hardened to bond them together. In addition, the crosspiece 77, which is shaped like a band plate and stands upright in the band width direction, abuts against the back surface 8b of the sound absorbing panel portion. the two are combined. At the portions of the frame portion 75 and the beams 77 that are in contact with the sound absorbing panel portion 8, the resin raw material g enters into the sound absorbing panel portion 8 having a porous structure and hardens during molding, and the frame portion 75, the beams 77 and the sound absorbing panel are formed. The part 8 is firmly integrated. Cavity surfaces 351 , 352 , 453 , 454 form a surface 751 , an outer surface 752 , a back-side thickness surface 753 , and a back-side inner surface 754 relating to the frame portion 75 . The horizontal beam 77A and the vertical beam 77B are formed by the cavity surfaces 47A and 47B. Although the crosspieces 77 for the framework are shown in a grid shape as shown in FIG. 1 for the sake of simplicity, the actual crosspieces 77 have more grids to supplement the strength required for the sound absorbing panel section 8 and make it robust. ing.

Simultaneously with the injection of the resin raw material g into the frame portion 75 and the crosspiece 77, the resin raw material g flows through the cavity C7 for the crosspiece into the cavity portion C1 formed by the recess 41, and the boss portion 73. Form. The boss portion 73 is a bottomed cylindrical boss portion 73 having a loophole 731 through which the pin 31 can be pulled out. The reason why the boss portion 73 is provided is to prevent noise from leaking from the through hole corresponding portion 80 that is inevitably formed by the pin 31 when the product is manufactured.

In this embodiment, the diameter of the through holes 50 provided in the porous sheet 5 is set to be smaller than the cross-sectional diameter of the base of the pin 31 in order to form the sound absorbing panel material 6 with good appearance. All the peripheries of the through holes 50 of the porous sheet 5 can be brought into close contact with the roots of the pins 31 . As shown in FIGS. 10A and 10B, the hole diameter d of the through hole 50 is smaller than the cross-sectional diameter D of the base of the pin 31 . If the hole diameter d of the through hole 50 is larger than the base cross-sectional diameter D of the pin 31 as shown in FIG. When the resin raw material g is injected into the recess 41, the resin raw material g seeps out to the surface side of the sound absorbing panel portion 8 as indicated by the arrow in FIG. . Not only is there a problem of appearance, but also the sound absorbing performance of the sound absorbing panel portion 8 is not deteriorated.

In addition, when the resin raw material g is injected into the cavity C after mold clamping, unnecessary penetration of the resin raw material g from the cavity portions C5 and C1 of the frame portion 75 and the boss portion 73 into the main body of the sound absorbing panel portion 8 is prevented. Biting protrusions 45f and 41f are provided to prevent the cutting. On the cavity surface of the movable mold 4, under mold clamping, on the cavity surface of the movable mold 4 related to the cavity portion C5 for the frame portion and the cavity portion C1 for the boss portion, along each peripheral edge in contact with the sound absorbing panel portion 8, the outer side thereof are provided with projections 45f and 41f projecting in a bank shape toward the sound absorbing panel portion 8 (FIG. 3). By clamping the projections 45f and 41f, the projections 45f and 41f bite into the sound absorbing panel portion 8 by the amount protruding toward the sound absorbing panel portion 8 from the surrounding cavity surface, further compressing the portion of the sound absorbing panel portion 8 having a porous structure to increase the density. This makes it difficult for the resin raw material g to permeate (Fig. 7). To prevent resin raw material g, which lowers the sound absorbing performance, from seeping into the main body range of the sound absorbing panel part 8 beyond the projection. 10, illustration of the projection 41f is omitted. Although not shown in the drawings, a biting projection is also provided near the outside of the cavity portion C7 of the crosspiece to prevent the resin raw material g from unnecessarily penetrating into the main body of the sound absorbing panel portion 8. As shown in FIG.

In this way, the porous sheet 5 which will be the sound absorbing panel portion 8 is used as an insert, and the synthetic resin molded portion 7 having the frame portion 75 and the crosspiece 77 for retaining the shape thereof is integrally molded. When the mold is removed after the integral molding, the frame portion 75 surrounds the sound absorbing panel portion 8 and the crosspieces 77 form a frame, thereby obtaining the desired sound absorbing panel material 6 that retains the shape of the sound absorbing panel portion 8 (Fig. 1, Fig. 1). 2). Reference numeral 79 denotes an attachment portion to the mating member, which is molded together with the frame portion 75 and the like. Reference numerals 75e and 73e in FIG. 8 indicate seal traces left by the biting projections 45f and 41f (not shown in FIG. 1). By providing the projections 45f and 41f on the movable mold 4 instead of on the fixed mold 3, the sealing marks 75e and 73e are not left on the surface 8a (designed surface) side, and the surface 8a (design surface) is favorable.

FIGS. 11 and 12 show another embodiment of the sound absorbing panel member 6 that replaces FIGS. 1 and 2. FIG. In this embodiment, each pin 31 is arranged in the region of the cavity portion related to the crossing portion 77CR of the vertical beam 77B and the horizontal beam 77A which are formed in a grid pattern by clamping. The movable mold 4 is provided with a recess 41 disposed in the region of the part cavity portion C5 and surrounding the pin 31 thereof. The deformed boss portion 73 formed by injecting the resin raw material g into the recess 41 under mold clamping and joining the cylindrical wall to the frame portion 75 as shown in FIG. regarded as a department. A desired sound absorbing panel member 6 shown in FIGS. 11 and 12 is obtained by a manufacturing method similar to the present manufacturing method described with reference to FIGS.

(2) Vehicle sound absorbing panel material The vehicle sound absorbing panel material 6 (here, “instrument panel undercover”) obtained by the above-described manufacturing method shown in FIGS. A synthetic resin molded portion 7 having a crosspiece 77 and a boss portion 73 which is a part of the synthetic resin molded portion 7 and provided in a bottomed cylindrical shape (FIGS. 1 and 2). . The sound absorbing panel part 8 is formed by forming the porous sheet 5 with two (plurality) through holes 50 while maintaining the porous structure, and the through holes 50 become the through hole corresponding part 80 and three-dimensionalized. It is a sheet-like panel body. The porous sheet 5 is cut in advance to the size of the sound absorbing panel portion 8, and is manufactured by the above-described manufacturing method or the like. In this embodiment, the porous sheet 5 is made of non-woven fabric, the porous structure is maintained, and the thickness t2 is made smaller than the initial thickness t1 of the non-woven fabric, and the sound absorption is shaped into a three-dimensional shape as shown in FIGS. It is called a panel section 8 . Since the shape of the sound absorbing panel portion 8 is changed, the through hole 50 provided in the porous sheet 5 is used as the through hole corresponding portion 80 .

The synthetic resin molded portion 7 surrounds the sound absorbing panel portion 8 and serves as a framework to retain the shape of the sound absorbing panel portion 8. The molded portion made of synthetic resin includes a frame portion 75 integrally formed with the sound absorbing panel portion 8 and a crosspiece 77. is. The frame part 75 surrounds and integrates the sound absorbing panel part 8, and the crosspiece 77 is formed by crossing the horizontal crosspieces 77A and the vertical crosspieces 77B in the frame part 75, and is connected to the sound absorbing panel part 8 at its base. are unified. During injection molding, the frame portion 75 and the crosspiece 77 that constitute the molded synthetic resin portion 7 are cured by part of the resin raw material g entering from the contact surface with the sound absorbing panel portion 8 to the sound absorbing panel portion 8 side and hardening. , are combined with the sound absorbing panel portion 8 . If the above-described manufacturing method is used, even if the mold is clamped and the porous sheet 5 is shaped into the sound absorbing panel portion 8, the porous structure remains, so the resin raw material for the cavity C after mold clamping. At the time of injection of g, the resin raw material g is impregnated into the porous structure gap, and the frame portion 75, the crosspiece 77 and the sound absorbing panel portion 8 can be strongly connected. A crosspiece 77 complements it.

The boss portion 73 is a part of the synthetic resin molded portion 7, and is a region of the frame portion 75 or crosspiece 77 integrated with the back surface 8b of the sound absorbing panel portion 8 where the through hole corresponding portion 80 is present. It is a protruded thick-walled portion having a loop hole 731 with a hole opening 730 aligned with the hole corresponding portion 80 . The boss portion 73 serves to close the through hole of the through hole corresponding portion 80 . Since the through hole of the through hole corresponding portion 80 is closed, noise is prevented from passing through the through hole, and the sound absorbing function of the sound absorbing panel material 6 of the present invention can be fully exhibited. In FIGS. 1 and 2, two (plural) boss portions 73 are formed at the crossing portion 77CR between the crosspieces 77 and 77. However, as shown in FIGS. may be The rest of the configuration is the same as the configuration described in (1) Manufacturing method of sound absorbing panel material for vehicle, so description thereof will be omitted.

(3) Effect In the sound absorbing panel material for a vehicle configured in this way and the manufacturing method thereof, the sound absorbing property is maintained by leaving the porous structure in the sound absorbing panel portion 8 corresponding to the panel main body portion, so the panel material 91 as in Patent Document 1 and the like can be used. Since there is no need to attach the sound absorbing material 92 as a separate member, the cost can be reduced. In addition, since the separate sound absorbing member 92 and its attachment tool, and the protective member for avoiding abrasion of the sound absorbing member 92 in Patent Document 1, etc. are not required, the weight can be reduced. In addition, since the sound-absorbing porous structure also appears on the surface 8a (design surface) of the sound-absorbing panel portion 8 on the side of the passenger compartment, unlike conventional products such as Patent Document 1, noise entering the passenger compartment from the outside of the vehicle is reflected. It is excellent in that it can absorb sound even when it hits the sound absorbing panel surface 8a.

As in this manufacturing method, the porous sheet 5 is set in the mold 2, and then the mold is clamped to form the sound absorbing panel portion 8 with the thickness t2 while maintaining the porous structure, and hold it. By molding the frame portion 75 and the crosspiece 77 that are shaped and integrated, the rigidity and mechanical strength of the sound absorbing panel portion 8 can be complemented by the frame portion 75 and the crosspiece 77 . Since the sound absorbing panel part 8 is assisted by the frame part 75 and the crosspiece 77, it is not necessary to strongly compress the porous sheet 5 to give the sound absorbing panel material 6 originally necessary strength. Together with a frame portion 75 that surrounds and reinforces the sound absorbing panel portion 8, a crosspiece 77 arranged in the frame portion 75 is combined and integrated with the sound absorbing panel portion 8 to complement the lack of rigidity and strength of the sound absorbing panel material 6. do. Therefore, the sound absorbing panel part 8 is not subject to strict restrictions on the rigidity and mechanical strength required for itself, and is shaped from the porous sheet 5, maintaining the required sound absorbing porous structure, and achieving the desired sound absorption. The sound absorbing panel portion 8, that is, the sound absorbing panel material 6, can fully exhibit its performance. Then, using an injection molding machine 1 as shown in FIG. 3, after heating the porous sheet 5, it is set in the mold 2, and then the mold is clamped and the resin raw material g is injected into the cavity C to absorb sound. Since the synthetic resin molded portion 7 such as the frame portion 75 and the crosspiece 77 is formed by insert molding the panel portion 8, the manufacturing time of the sound absorbing panel material 6 can be shortened.

In addition, a plurality of pins 31 are protruded from the cavity surface 33 on which the porous sheet 5 is set in one of the molds 3 , and when the porous sheet 5 is inserted into each of the pins 31 and set, the mold 2 is formed. position setting of the porous sheet 5 is automatically enabled. If the porous sheet 5 is cut in advance to the size of the sound absorbing panel portion 8, it is heated and clamped as shown in FIG. A sound absorbing panel material 6 in which the frame portion 75 and the crosspiece 77 are integrated can be formed. With respect to the sound absorbing panel portion 8, post-processing such as trimming cut can be omitted. Contribute to productivity improvement.

Furthermore, the position of the pin 31 is arranged in the region of the cavity portions C5 and C7 related to the frame portion 75 or the crosspiece 77, and the recess 41 for covering the pin 31 is provided in the other mold 4, so that the frame portion 75 and the crosspiece 77 are arranged. At the same time, when the boss portion 73 having the loop hole 731 through which the pin 31 is pulled out is formed in the cavity portion C1 formed by the recess 41, the communication formed by providing the pin 31 in the sound absorbing panel portion 8 is formed. The through hole of the hole corresponding portion 80 can be closed with the boss portion 73 . Even if the pin 31 is used for the positioning and setting of the porous sheet 5 for the sound absorbing panel portion, the sound absorbing effect is not deteriorated at the portion 80 corresponding to the through hole formed by the pin 31 . Moreover, the trouble of closing the through-hole of the through-hole corresponding portion 80 by post-processing becomes unnecessary. Since the boss portion 73 can be integrally formed with the sound absorbing panel portion 8 at the same time as the frame portion 75, the crosspiece 77, etc., no additional work process is required. Furthermore, the frame 77 of the frame portion 75 is formed in a lattice shape, and the other mold 4 is provided with a recess 41 for covering the pin 31 by clamping, and the position of the pin is formed in a lattice shape. When the resin raw material g is injected into the cavity C after mold clamping, the resin raw material g passes through the cavity portion C7 of the crosspiece 77 and into the recess 41. You can easily inject g. Since the concave portion 41 is filled with the resin raw material g and the bottomed cylindrical boss portion 73 covering the pin 31 is formed, the boss portion 73 not only closes the through hole corresponding portion 80 but also reinforces the intersection portion 77CR with the boss portion 73. becomes possible.

In addition, if the porous sheet 5 is made of nonwoven fabric in which a low-melting point material and a high-melting point material are mixed, the non-woven fabric is heated, clamped, and shaped into the sound absorbing panel part 8 with a high-melting fiber material. , the shape can be easily maintained by the adhesiveness of the low-melting-point fiber material. When the nonwoven fabric of the core-sheath structure fiber is used, the sheath portion is made of a low-melting-point fiber, and the heat-sealing is carried out, so that the sound-absorbing panel portion 8 having a porous structure can be smoothly shaped.

It should be noted that the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the present invention according to the purpose and application. The shape, size, number, material, etc. of the injection molding machine 1, the mold 2, the porous sheet 5, the boss portion 73, the frame portion 75, the crosspiece 77, the sound absorbing panel portion 8, etc. can be appropriately selected according to the application. Further, in the present embodiment, the porous sheet 5 is heated and then shaped by the mold 2, but if there is no problem in shaping the porous sheet 5, the heating may be omitted. Furthermore, in the present embodiment, one mold 3 is fixed and the other mold 4 is movable, but one mold 3 may be movable and the other mold 4 may be fixed. Although the sound absorbing panel material 6 of the present embodiment is used as an undercover for an instrument panel, it can of course be applied to an engine undercover or the like.

REFERENCE SIGNS LIST 1 injection molding machine 3 one mold (fixed mold) 31 pin 4 other mold (movable mold) 41 recess 5 porous sheet 50 through-hole 6 sound absorbing panel material for vehicle (sound absorbing panel material) 7 synthetic resin molded part 73 boss Portion 730 Hole 731 Hole for pin 75 Frame 77 Crosspiece 8 Sound absorbing panel C Cavity C1 Cavity portion formed by recess C3 Cavity portion of porous sheet C5 Cavity portion of frame C7 Cavity portion of crosspiece

Claims (7)

A pin protrudes from the cavity surface where a sheet of a desired size is set in one of the molds. A pair of molds in which a cavity portion of a framework beam is formed, the position of the pin is arranged in the region of the cavity portion related to the frame portion or the beam, and the other mold is provided with a recess for covering the pin. Using an injection molding machine equipped with a mold consisting of a mold, the sheet is made into a porous sheet, the porous sheet is inserted into the pin and set, and then the mold is clamped to maintain the porous structure. Along with molding of the frame and crosspieces that form a sound absorbing panel portion and retain and integrate it, a loophole through which the pin escapes is formed in the cavity portion formed by the recess. A method for manufacturing a sound absorbing panel material for a vehicle, characterized by forming a bottomed cylindrical boss portion. In the one mold, a plurality of the pins are spaced apart from each other and protrude from the cavity surface where the sheet is set, and each position of the pins is arranged in the region of the cavity portion related to the frame or the crosspiece, 2. The method of manufacturing a sound absorbing panel material for a vehicle according to claim 1, wherein the other mold is provided with recesses for covering the pins. 3. The method for producing a vehicle sound absorbing panel material according to claim 1, wherein the porous sheet is a nonwoven fabric. The framing crosspieces of the frame are formed in a lattice shape, and the positions of the plurality of pins provided by the mold clamping are located in the region of the cavity portion related to the intersection of the crosspieces formed in the lattice shape. 4. A method for manufacturing a vehicle sound absorbing panel material according to any one of claims 1 to 3. 5. The porous sheet according to any one of claims 1 to 4, wherein the porous sheet is made of a nonwoven fabric in which a low-melting point material and a high-melting point material are mixed, and after the porous sheet is heated, it is inserted into the pins and set in one of the molds. 10. A method for manufacturing the vehicle sound absorbing panel material according to 1. above. 2. A through hole having a hole diameter smaller than the cross-sectional diameter of the root of said pin is provided at a point of said porous sheet into which said pin is inserted, and said pin is inserted into said through hole to set said porous sheet. 6. A method for manufacturing a vehicle sound absorbing panel material according to any one of items 1 to 5. A sound-absorbing panel section in which a porous sheet having a plurality of through-holes is shaped while maintaining a porous structure, and the through-holes serve as through-hole-corresponding sections, and a three-dimensional sound-absorbing panel section is provided around the sound-absorbing panel section. A synthetic resin molded part that surrounds and frames the sound absorbing panel part and includes a frame part and a crosspiece integrally molded with the sound absorbing panel part to retain the shape of the sound absorbing panel part, and a part of the synthetic resin molding part that is the sound absorbing panel In the area where the through-hole corresponding part exists of the frame part or the crosspiece integrated with the back surface of the part, the opening is aligned with the through-hole corresponding part, and is provided in a bottomed cylindrical shape having the loophole A sound absorbing panel material for a vehicle, comprising: a boss portion;

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