JP2023062384A - Ultrasonic horn for fixing automotive sound absorbing material, method for producing fixing structure for automotive sound absorbing material, and fixing structure for automotive sound absorbing material - Google Patents

Abstract

To provide an ultrasonic horn for fixing an automotive sound absorbing material, a method for producing a fixing structure for the automotive sound absorbing material, and a fixing structure for the automotive sound absorbing material, which fixes the automotive sound absorbing material by ultrasonic vibration at a deep position in a fiber-based base material and maintains stable fixing strength at a fixing point.SOLUTION: A ultrasonic horn 5 for fixing an automotive sound absorbing material is used to produce a fixing structure for the automotive sound absorbing material 3, in which a fixing part 14 of the automotive sound absorbing material 3 layered on a base material 2, which is a fiber molded body containing thermoplastic synthetic resin, is fixed to the base material 2. In a production of fixing structure of the sound absorbing material 3 for automotive use, the ultrasonic horn 5 includes: a pressing surface 23 for applying a pressing force to the fixing part 14 to push the fixing part 14 into the base material 2; and a transmission part 21 that realizes transmission of ultrasonic vibration from the pressing surface 23 toward the fixing part 14. The pressing surface 23 has a shape in which a displacement area 26 is set on a peripheral edge part such that a pressing depth of the fixing part 14 into the base material 2 becomes shallower toward an outer periphery.SELECTED DRAWING: Figure 7

Description

TECHNICAL FIELD The present invention relates to an ultrasonic horn for fixing a vehicle-mounted sound absorbing material, a method for producing a vehicle-mounted sound absorbing material fixing structure, and a vehicle-mounted sound absorbing material fixing structure.

2. Description of the Related Art Conventionally, there are known various vehicle interior and exterior materials to which a sound absorbing material is fixed for absorbing noise from the exterior of the vehicle into the interior of the vehicle. Ultrasonic welding is one method of fixing the sound absorbing material. For example, Japanese Unexamined Patent Application Publication No. 2002-100002 discloses a vehicle ceiling material in which felt made of a fiber material is fixed to a base material using a rod-shaped ultrasonic horn. In this ultrasonic welding, a part of the laminate constituting the base material is melted by heat caused by the vibrational energy to generate molten resin. The felt is adhered to the substrate by the molten resin entangling with the fibers forming the felt and solidifying. Since the ultrasonic horn is pressed against the upper surface of the felt and pushed to a predetermined depth in the base material, the felt located immediately below and near the ultrasonic horn is elastically deformed by compression.

In recent years, in order to improve the sound absorbing performance of the base material, it has become common to increase the thickness of the fiber-based base material and apply ultrasonic welding to the thick part to attach the sound absorbing material. In this case, in order to sufficiently transmit the vibrational energy of the ultrasonic horn in the portion where the fiber web layer is thick, it is necessary to push the ultrasonic horn deeper into the base material. In addition, vehicle exterior materials such as undercovers are more susceptible to external influences than vehicle interior materials, and require stable fixing strength for sound absorbing materials.

JP 2006-272709 A

However, when the ultrasonic horn is pushed deep into the fiber-based base material to fix the sound absorbing material, the pulling force in the direction in which the sound absorbing material is pushed in increases, and the peripheral edge of the fixed portion is likely to break. Become. When a load is applied from the outside to the fixed portion of the sound absorbing material in the state where the tear occurs, the sound absorbing material is torn starting from the tear. Furthermore, since there are variations in the location and extent of the breakage, there is a problem that the strength of adhesion to the base material becomes unstable, and the sound absorbing material tends to come off.

The present invention has been invented in view of such points, and the problem to be solved by the present invention is to fix a vehicle-mounted sound absorbing material by ultrasonic vibration at a deep position in a fiber base material, and to fix it. To provide an ultrasonic horn for fixing an on-vehicle sound absorbing material, a method for producing a fixing structure for the on-vehicle sound absorbing material, and a fixing structure for the on-vehicle sound absorbing material, in which a stable fixing strength is maintained at a point.

One of the characteristics of the ultrasonic horn for fixing an automotive sound absorbing material that solves the above problems is that the fixing portion of the automotive sound absorbing material superimposed on the base material, which is a fiber molded body containing a thermoplastic synthetic resin, is attached to the base material. An ultrasonic horn for fixing a sound absorbing material for a vehicle, which is provided for producing a structure for fixing a sound absorbing material for a vehicle, which is fixed to a material. It has a pressing surface for applying a pressing force for pressing the base material to the fixing portion, and a transmission portion for realizing transmission of ultrasonic vibration from the pressing surface toward the fixing portion. In addition, a displacement area is set such that the depth of pressing of the fixing portion into the base material becomes shallower toward the outer periphery.

One of the features and advantages of the above configuration is that the pressure surface of the ultrasonic horn acts on the fixed portion of the sound absorbing material to press the fixed portion of the sound absorbing material into the base material. The fixed portion is fixed by denaturation of the base material and the sound absorbing material due to the vibration energy of the ultrasonic vibration. A peripheral edge portion of the pressing surface is provided with a displacement area in which the pressing depth of the fixing portion into the base material becomes shallower toward the outer periphery. Since the fixed portion pushed into the ultrasonic horn is recessed according to the shape of the pressing surface, the pressing force is relatively small at the portion in contact with the displacement area of the pressing surface, and the force with which the sound absorbing material is pulled can be moderated. In addition, the pressing surface transmits ultrasonic vibrations to the shallow portion of the peripheral edge of the fixing portion, thereby fixing the fixing portion. As a result, the sound absorbing material is pushed to a depth position where the ultrasonic vibration can be sufficiently transmitted to the base material, which is a fiber molded body, and the sound absorbing material is fixed. You can prevent it from happening.

In the above-described ultrasonic horn for fixing a sound absorbing member for mounting on a vehicle, the displacement area may have a concave surface shape that is concave toward the side opposite to the base material when the pressing force is applied.

One of the features and advantages of the above configuration is that the displacement area of the pressing surface has a concave curved surface shape that is concave on the opposite side of the substrate. As a result, when the pressing surface applies a pressing force to the fixing portion of the sound absorbing material, the force with which the sound absorbing material is pulled at the peripheral edge of the fixing portion can be made more gentle.

One feature of the method for producing a structure for fixing an in-vehicle sound absorbing material using the ultrasonic horn for fixing an in-vehicle sound absorbing material is that the fixing portion of the in-vehicle sound absorbing material in a state of being superimposed on the base material a pressing step of applying the pressing force from the pressing surface of the ultrasonic horn to the pressing step of pressing the fixing portion into the base material; and and a fixing step of transmitting ultrasonic vibrations from a transmitting portion, and fixing the base material and at least a part of the fixing portion by denaturing them with the ultrasonic vibrations.

One of the characteristics and advantages of the above production method is that the ultrasonic horn having a displacement area on the pressing surface is used to fix the vehicle-mounted sound absorbing material to the substrate, which is a fiber molded body. In the pressing step, the fixed portion of the sound absorbing material pressed into the pressing surface receives a relatively gentle pressing force at the portion that contacts the displacement area. As a result, the force with which the fixed portion is pulled becomes moderate, and it is possible to suppress the occurrence of tearing at the peripheral edge of the fixed portion. Further, in the fixing step, ultrasonic vibrations are transmitted to the base material and the fixing part via the pressing surface, and at least a part of the base material and the fixing part is modified by the vibration energy of the ultrasonic vibrations. As a result, the fixing portion is fixed even at the shallow part of the peripheral edge, so that it is possible to maintain a stable fixing strength against the load from the outside.

One of the characteristics of the fixed structure of the automotive sound absorbing material is the base material, which is a fiber molding containing thermoplastic synthetic resin, and the laminate of a planar fiber web containing thermoplastic synthetic fiber and non-woven fabric. a sound absorbing material, wherein the base material has a sound absorbing surface that absorbs noise inside and outside the vehicle, and a crimped portion that is relatively compressed in a thickness direction relative to the sound absorbing surface; The material has a fixing portion in which the in-vehicle sound absorbing material is superimposed and fixed to the sound absorbing surface of the base material, and the fixing portion is formed by pressing the in-vehicle sound absorbing material into the base material. It has a concave portion, and the concave portion is fixed by denaturing the base material and at least a part of the fixing portion by ultrasonic vibration, and the depth of the concave portion is directed to the outer periphery at the peripheral edge portion of the concave portion. It has a displacement part that becomes shallower as it goes.

One of the features and advantages of the above configuration is that the vehicle-mounted sound absorbing material is fixed to the sound absorbing surface of the base material having a relatively thick plate thickness. The fixing part has a recess formed by being pushed into the base material to a set depth. The concave portion has a displacement portion in the peripheral portion thereof, the depth of the concave portion becoming shallower toward the outer circumference. Due to the shape of this concave portion, the force with which the sound absorbing material is pulled at the peripheral edge portion is moderately suppressed, and the occurrence of tearing at the peripheral edge of the fixing portion of the sound absorbing material is suppressed. In addition, the ultrasonic vibration is transmitted to the fixed portion over the entire concave portion including the displacement portion, and the base material and the fixed portion are denatured and fixed by the vibration energy of the ultrasonic vibration. As a result, the sound absorbing material is fixed at a depth position where ultrasonic vibrations can be sufficiently transmitted to the base material, which is a fiber molded body, and the fixing strength of the sound absorbing material is maintained stably against the load from the outside.

In the fixing structure of the in-vehicle sound absorbing material, the displacement portion may have a convex curved surface shape that protrudes toward the side opposite to the base material.

One of the features and advantages of the above configuration is that the displacement portion in the concave portion of the fixing portion presents a convex curved shape that is convex on the opposite side with respect to the base material. As a result, the force with which the sound absorbing material pushed to the set depth of the base material is pulled at the peripheral edge of the fixing portion can be made more gentle.

According to the present invention, by adopting the above configuration or production method, the vehicle-mounted sound absorbing material can be fixed by ultrasonic vibration at a deep position in the fiber-based base material, and a vehicle-mounted sound absorbing material can maintain a stable fixing strength at the fixing point. A method for producing an ultrasonic horn for fixing, a fixing structure for a sound absorbing material for a vehicle, and a fixing structure for a sound absorbing material for a vehicle can be provided.

1 is an overall perspective view of a base material and a sound absorbing material that constitute a vehicle exterior material according to an embodiment; FIG. FIG. 4 is a side view schematically showing a fixing portion of the vehicle exterior material; It is a top view which shows a fixing part typically. It is a side view of the tool horn concerning an embodiment. It is a figure which shows the pressing surface seen from the axial direction of the tool horn. It is a figure which shows typically the process of overlapping a sound-absorbing material on a base material. It is a figure which shows typically the state in which the sound-absorbing material was pushed into the base material by the tool horn.

An embodiment of the present invention will be described below with reference to FIGS. 1 to 7. FIG.

<Fixation structure of automotive sound absorbing material>
As a fixing structure of the vehicle-mounted sound absorbing material according to the present embodiment, the structure of the vehicle exterior material 1 will be described as an example. Examples of the vehicle exterior material 1 include a body undercover and an engine undercover. For example, the body undercover is attached to the lower part of the vehicle so as to cover the lower surface of the vehicle in order to suppress the air resistance of the airflow flowing under the vehicle. As shown in FIG. 1, the vehicle exterior material 1 is a laminate of a substrate 2, which is a fiber molding containing a thermoplastic synthetic resin, and a planar fiber web containing a thermoplastic synthetic fiber and a non-woven fabric. It has a sound absorbing material 3 (in-vehicle sound absorbing material). The sound absorbing material 3 is fixed to the base material 2 so as to be positioned between the lower surface of the vehicle and the base material 2 .

The base material 2 is a fiber molded body molded into a three-dimensional surface shape including a fiber layer having a thermoplastic synthetic resin and a fiber reinforcing material. A nonwoven fabric made of a thermoplastic synthetic resin or the like may be appropriately laminated on one side or both sides of the fiber layer. The fiber layer can be formed by either a dry method typified by cloth layer, air lay, or the like, or a wet method typified by a papermaking method. Thermoplastic synthetic fibers such as polyethylene fibers, polyester fibers and polypropylene fibers may be selected as the thermoplastic synthetic resin in the dry method. Powders of polyethylene, polyester, polypropylene, etc. can be selected as the thermoplastic synthetic resin when a wet method (papermaking method) is used. As the fiber reinforcing material, natural fibers such as kenaf (hemp) and bamboo can be appropriately selected in addition to glass fiber, basalt fiber and carbon fiber.

The sound absorbing material 3 is formed by laminating a planar nonwoven fabric containing thermoplastic synthetic fibers as a cover layer on both sides of a planar fiber web containing thermoplastic synthetic fibers. The sound absorbing material 3 is molded into a shape corresponding to the base material 2 to be fixed, and the fiber web is compressed in the thickness direction along the entire periphery along the periphery. Thermoplastic synthetic fibers can be selected from the group consisting of polyethylene fibers, polypropylene fibers, polystyrene fibers, polyester fibers, etc., and mixtures thereof. The nonwoven fabric of the cover layer may be water repellent.

The base material 2 has a sound absorbing surface 10 that absorbs noise inside and outside the vehicle, and a crimping portion 12 that is relatively compressed in the thickness direction relative to the sound absorbing surface 10 . The crimped portion 12 has a higher strength than the sound absorbing surface 10 and maintains the rigidity of the fiber molding. The crimping portion 12 is provided on a surface of the base material 2 along the vehicle bottom surface, and also on a flange portion that bends and extends from the outer peripheral edge of the base material 2 toward the vehicle side and is connected to the vehicle bottom surface. By providing the sound absorbing surface 10 and the crimping portion 12 having different plate thicknesses on the base material 2, which is a fiber molded body, both the sound absorbing function and the shape retention of the base material 2 can be achieved. The shape of the base material 2 and the arrangement of the sound absorbing surface 10 and the pressure-bonding portion 12 are appropriately set according to the shape of the underside of the vehicle. A sound absorbing material 3 is fixed to the sound absorbing surface 10 in a state of being superimposed on the surface of the base material 2 facing the lower surface of the vehicle. The sound absorbing material 3 has a plurality of fixing portions 14 along its outer periphery, and is fixed to the sound absorbing surface 10 at the fixing portions 14 .

As shown in FIGS. 2 and 3, the fixed portion 14 has a recess 15 formed by pressing the sound absorbing material 3 into the base material 2 . The concave portion 15 has a circular shape in plan view, and has a bottom portion 17 and a displacement portion 18 . The bottom portion 17 is the deepest portion of the recess 15 and has a circular planar shape. The displacement portion 18 is a portion of the peripheral portion of the recess 15 in which the depth of the recess 15 becomes shallower toward the outer periphery, and has a convex curved shape that protrudes toward the side opposite to the base material 2 . The shape of the displacement portion 18 can be appropriately selected from, for example, a round surface, an R surface, a fillet surface (fillet), an angular surface, a C surface, and the like.

The concave portion 15 is fixed to the base material 2 by denaturing at least a part of the fixing portion 14 by ultrasonic vibration. Specifically, the thermoplastic synthetic resin contained in the base material 2 and the thermoplastic synthetic fiber contained in the sound absorbing material 3 are thermally melted by the vibration energy of the ultrasonic vibration and solidified, thereby being welded together. Here, a portion where the base material 2 and the fixed portion 14 are denatured by ultrasonic vibration is referred to as a denatured portion 15a. The modified portion 15 a is formed over the bottom portion 17 and the displacement portion 18 .

<Structure of ultrasonic horn for fixing automotive sound absorbing material>
Next, a tool horn 5 for ultrasonic welding will be described as an example of an ultrasonic horn for fixing an in-vehicle sound absorbing material according to the present embodiment. The tool horn 5 has a sound absorbing material fixing structure for a vehicle in which a fixing portion 14 of a sound absorbing material 3 superimposed on a base material 2, which is a fiber molding containing a thermoplastic synthetic resin, is fixed to the base material 2. It is provided for production.

The tool horn 5 is made of a metal material and shaped like a long bar in the axial direction. As shown in FIGS. 4 and 5, the tool horn 5 has a transmission portion 21 that axially transmits ultrasonic vibrations input from the ultrasonic transducer. The transmitting portion 21 includes a cylindrical large-diameter portion 21a connected to the ultrasonic transducer, and a small-diameter portion 21c extending from the large-diameter portion 21a toward the tip 21b so as to have a smaller outer diameter than the large-diameter portion 21a. have. The tool horn 5 has a pressing surface 23 at the tip 21 b of the transmission portion 21 . The pressing surface 23 is a surface facing the surface of the sound absorbing material 3 in production of the fixing structure of the sound absorbing material 3 (vehicle sound absorbing material), and applies a pressing force to the fixing part 14 to press the fixing part 14 into the base material 2. Let The transmission portion 21 realizes transmission of ultrasonic vibration from the pressing surface 23 toward the fixing portion 14 .

The pressing surface 23 has an end surface portion 25 and a displacement area 26 . The end face portion 25 has a circular planar shape when viewed from the axial direction of the tool horn 5, and is a portion where the fixing portion 14 is pushed into the base material 2 to the greatest depth. The displacement area 26 is set on the peripheral edge of the pressing surface 23, i.e., on the outer peripheral side of the end surface 25, and has a shape in which the pressing depth of the fixing portion 14 into the base material 2 becomes shallower toward the outer periphery. In the present embodiment, the fixing portion 14 has a concave curved surface shape that becomes concave toward the side opposite to the base material 2 when a pressing force is applied to the fixing portion 14 . The shape of the displacement area 26 can be appropriately selected from, for example, a fillet surface, a round surface, an R surface, an angular surface, a C surface, and the like.

By providing the displacement area 26 on the pressing surface 23 of the tool horn 5, the recessed portion 15 of the fixing portion 14 is formed in a developed shape so that the depth becomes shallower from the bottom portion 17 toward the outer periphery. Therefore, when the sound absorbing material 3 is pushed into the base material 2 by the tool horn 5, the force with which the sound absorbing material 3 is pulled becomes gentle, and the occurrence of breakage at the peripheral edge of the recess 15 can be suppressed. Further, the deformed portion 15a is formed not only at the bottom surface portion 17 but also at the peripheral portion of the concave portion 15, that is, the displacement portion 18, by ultrasonic welding. Therefore, even if the displacement portion 18 is torn, the fixing portion 14 is welded over the entire concave portion 15 including the displacement portion 18, so that the fixing strength can be maintained. In this manner, the pressing surface 23 is shaped so that the tearing portion of the fixing portion 14 is accommodated inside the concave portion 15 .

The shape and size of the tool horn 5 are appropriately set according to the material, plate thickness, etc. of the base material 2 and the sound absorbing material 3 . For example, the diameter, width, depth, etc. of the concave portion 15 are set so that the vibration energy is sufficiently transmitted to the thickness of the sound absorbing surface 10 of the base material 2 and the fixed portion 14 and the base material 2 are thermally welded. . The shape and size of the pressing surface 23 of the tool horn 5 are set according to the size of the recess 15 . Further, the planar shape of the end surface portion 25 is not limited to a circular shape, and any other shape may be selected.

<Process of producing fixing structure for automotive sound absorbing material>
Next, a description will be given of the process of producing the structure for fixing the vehicle-mounted sound absorbing material according to the above-described embodiment. The fiber molded body that constitutes the base material 2 of the vehicle exterior material 1 is subjected to a heating process of heating and softening a laminate obtained by laminating another nonwoven fabric on a fiber layer containing a thermoplastic synthetic resin and a fiber reinforcing material, and a heating process. The laminated body heated in step 1 is sandwiched between both sides of the press mold and pressed while being cooled, and formed into a three-dimensional surface shape along the underside of the vehicle. In the press molding process, the sound absorbing surface 10 and the crimping portion 12 are molded. The sound absorbing surface 10 is a surface that absorbs noise inside and outside the vehicle. The crimped portion 12 is a portion that is relatively compressed in the thickness direction with respect to the sound absorbing surface 10 . The crimping portion 12 is provided on a surface of the base material 2 along the underside of the vehicle, and also on a flange portion that bends and extends from the outer peripheral edge of the base material 2 toward the vehicle side and is connected to the underside of the vehicle.

By using the tool horn 5, the base material 2 and the sound absorbing material 3 of the vehicle exterior material 1 are fixed through a pressing process and a fixing process. Specifically, as shown in FIG. 6, the base material 2 which is a fiber molded body is placed on a base (not shown), and the sound absorbing material 3 is laminated on the sound absorbing surface 10 of the base material 2 . The sound absorbing material 3 has a fixing portion 14 along its outer peripheral edge. In the pressing step, as shown in FIG. 7, a pressing force is applied from the pressing surface 23 of the tool horn 5 to the fixing portion 14 of the sound absorbing material 3 in the state of being superimposed on the base material 2 in the thickness direction. A concave portion 15 is formed at a portion of the fixing portion 14 that contacts the pressing surface 23 by pressing the fixing portion 14 into the base material 2 with the pressing force.

In the fixing step, ultrasonic vibration is transmitted from the transmission part 21 of the tool horn 5 to the fixing part 14 pushed into the base material 2 by the tool horn 5 via the pressing surface 23 . At least a part of the base material 2 and the fixing portion 14 in the concave portion 15 is denatured and fixed by the vibration energy of the ultrasonic vibration. That is, the thermoplastic synthetic resin contained in the base material 2 and the thermoplastic synthetic fiber contained in the sound absorbing material 3 are thermally melted by vibration energy and solidified by ultrasonic welding.

In the fixed portion 14 subjected to ultrasonic welding, a bottom portion 17, which is the deepest portion of the recess 15, is formed at a portion in contact with the end surface portion 25 of the pressing surface 23, and a recess 15 is formed at a portion in contact with the displacement area 26. A displacement portion 18 whose depth becomes shallower toward the outer periphery is formed. The bottom portion 17 has a circular planar shape. The displacement portion 18 has a convex curved shape that is convex toward the side opposite to the base material 2 . Referring to FIG. 2 , a modified portion 15 a formed by modifying and fixing the base material 2 and the fixing portion 14 is formed over the bottom surface portion 17 and the displacement portion 18 .

According to the configuration according to the above-described embodiment, the pressing surface 23 of the tool horn 5 (vehicle-mounted sound absorbing material fixing ultrasonic horn) presses the fixing portion 14 of the sound-absorbing material 3 (vehicle-mounted sound absorbing material) into the base material 2. Pressure acts on the anchor 14 . The fixed portion 14 is fixed by denaturation of the base material 2 and the sound absorbing material 3 by the vibration energy of the ultrasonic vibration. A peripheral portion of the pressing surface 23 is provided with a displacement area 26 in which the pressing depth of the fixing portion 14 into the base material 2 becomes shallower toward the outer periphery. Since the fixing portion 14 pushed into the tool horn 5 is recessed according to the shape of the pressing surface 23, the pressing force is relatively small at the portion of the pressing surface 23 that is in contact with the displacement area 26, and the force with which the sound absorbing material 3 is pulled. can be relaxed. Further, the pressing surface 23 allows the ultrasonic vibration to be transmitted to the shallow portion of the peripheral edge of the fixing portion 14 , thereby fixing the fixing portion 14 . As a result, the sound absorbing material 3 is pushed into the base material 2, which is a fiber molded body, to a depth position where ultrasonic vibrations can be sufficiently transmitted, and the sound absorbing material 3 is fixed. In addition, it is possible to suppress the occurrence of tearing.

Further, the displacement area 26 of the tool horn 5 presents a concave curved surface shape that becomes concave toward the side opposite to the base material 2 when the pressing force is applied. As a result, when the pressing surface 23 applies a pressing force to the fixing portion 14 of the sound absorbing material 3 , the force with which the sound absorbing material 3 is pulled at the peripheral edge of the fixing portion 14 can be made more moderate.

In the process of producing the fixing structure of the sound absorbing material 3, the sound absorbing material 3 is fixed to the base material 2, which is a fiber molding, using a tool horn 5 having a displacement area 26 on the pressing surface 23. FIG. In the pressing step, the fixed portion 14 of the sound absorbing material 3 pushed into the pressing surface 23 receives a relatively gentle pressing force at the portion that contacts the displacement area 26 . As a result, the force with which the fixing portion 14 is pulled becomes moderate, and the occurrence of tearing at the peripheral edge of the fixing portion 14 can be suppressed. Further, in the fixing step, ultrasonic vibrations are transmitted to the base material 2 and the fixing part 14 through the pressing surface 23, and at least a part of the base material 2 and the fixing part 14 are denatured by the vibration energy of the ultrasonic vibrations. As a result, the fixing portion 14 is fixed even at the shallow portion of the peripheral edge, so that it is possible to maintain a stable fixing strength against the load from the outside.

In the fixing structure of the sound absorbing material 3, the sound absorbing material 3 is fixed to the relatively thick sound absorbing surface 10 of the base material 2. As shown in FIG. The fixing portion 14 has a recess 15 formed by pressing the substrate 2 to a set depth. The concave portion 15 has a displacement portion 18 at its peripheral portion, the depth of the concave portion 15 becoming shallower toward the outer circumference. Due to the shape of this concave portion 15 , the force that pulls the sound absorbing material 3 at the peripheral edge is moderately suppressed, and the occurrence of tearing at the peripheral edge of the fixing portion 14 of the sound absorbing material 3 is suppressed. In addition, the ultrasonic vibration is transmitted to the fixing portion 14 over the entire concave portion 15 including the displacement portion 18, and the base material 2 and the fixing portion 14 are denatured and fixed by the vibration energy of the ultrasonic vibration. As a result, the sound absorbing material 3 is fixed at a depth position where ultrasonic vibrations can be sufficiently transmitted to the base material 2, which is a fiber molded body, and a stable fixing strength of the sound absorbing material 3 is maintained against external loads. .

Further, regarding the fixing structure of the sound absorbing material 3 , the displacement portion 18 in the concave portion 15 of the fixing portion 14 presents a convex curved surface shape that protrudes on the opposite side of the base material 2 . As a result, the force with which the sound absorbing material 3 pushed to the set depth of the base material 2 is pulled at the peripheral edge of the fixing portion 14 can be made more gentle.

A displacement area 26 provided on the pressing surface 23 of the tool horn 5 forms a displacement portion 18 on the periphery of the recess 15 . Displacement portion 18 is formed in a developed shape such that the depth of concave portion 15 becomes shallower from bottom surface portion 17 toward the outer periphery. As a result, when the sound absorbing material 3 is pushed into the base material 2 by the tool horn 5, the sound absorbing material 3 can be prevented from being suddenly pulled at the displacement portion 18 and broken, and the fixing strength of the fixing portion 14 can be improved. can be achieved. In addition, in the fixing portion 14, not only the bottom surface portion 17 but also the displacement portion 18 is subjected to ultrasonic vibration through the pressing surface 23, thereby forming the welded modified portion 15a. As a result, even if the displacement portion 18 is torn, the portion where the torn portion is torn is located inside the recess 15, i.e., within the welded range, so that stable fixing strength can be maintained.

The depth (height) of the displacement area 26 of the tool horn 5 is set corresponding to the depth of the recess 15 . As a result, even when performing ultrasonic welding manually, it is easy to visually confirm the depth of pushing into the base material 2, and welding can be performed at an appropriate depth. Therefore, variations in the depth of the concave portion 15 can be suppressed, and the fixing strength can be stabilized.

The ultrasonic horn for fixing an in-vehicle sound absorbing material, the method for producing the fixing structure of the in-vehicle sound absorbing material, and the fixing structure of the in-vehicle sound absorbing material according to the present invention are not limited to the appearance and configuration described in the above embodiments, and the present invention Various modifications, additions, deletions, and combinations of configurations can be implemented in various other forms without changing the gist of the invention. For example, as the fixing structure of the in-vehicle sound absorbing material of the present embodiment, an example in which the sound absorbing material is fixed to the vehicle exterior material is shown, but it is not limited to this, and can also be applied to a vehicle interior material using a fiber-based base material. can.

1 vehicle exterior material 2 base material 3 sound absorbing material (vehicle sound absorbing material)
5 Tool horn (ultrasonic horn for fixing automotive sound absorbing material)
10 Sound absorbing surface 12 Crimp portion 14 Fixed portion 15 Recessed portion 15a Modified portion 17 Bottom portion 18 Displacement portion 21 Transmission portion 23 Pressing surface 25 End surface portion 26 Displacement area

Claims (5)

It is used to produce a fixing structure of an in-vehicle sound absorbing material in which a fixed portion of the in-vehicle sound absorbing material is superimposed on a base material that is a fiber molded body containing a thermoplastic synthetic resin and fixed to the base material. An ultrasonic horn for fixing an in-vehicle sound absorbing material,
a pressing surface for applying a pressing force to the fixing portion to press the fixing portion into the base material in the production of the structure for fixing the vehicle-mounted sound absorbing material;
a transmission part that realizes transmission of ultrasonic vibration from the pressing surface toward the fixing part,
An ultrasonic horn for fixing an on-vehicle sound absorbing material, wherein the pressing surface has a shape in which a displacement area is set on the peripheral edge of the pressing surface so that the pressing depth of the fixing portion into the base material becomes shallower toward the outer periphery. The ultrasonic horn for fixing an in-vehicle sound absorbing material according to claim 1,
The ultrasonic horn for fixing an on-vehicle sound absorbing member, wherein the displacement area has a concave curved surface shape that becomes concave toward the side opposite to the base material when the pressing force is applied. A method for producing a structure for fixing an in-vehicle sound absorbing material using the ultrasonic horn for fixing an in-vehicle sound absorbing material according to claim 1 or 2, comprising:
a pressing step of applying the pressing force from the pressing surface of the ultrasonic horn to the fixed portion of the in-vehicle sound absorbing material in a state of being superimposed on the base material, thereby pushing the fixed portion into the base material;
Ultrasonic vibration is transmitted from the transmission part of the ultrasonic horn to the fixing part in a state of being pushed into the base material, and at least a part of the base material and the fixing part are denatured by the ultrasonic vibration and fixed to each other. and a fixing step for producing a fixing structure for a vehicle-mounted sound absorbing material. A fixing structure for an in-vehicle sound absorbing material,
a base material that is a fiber molding containing a thermoplastic synthetic resin;
A planar fiber web containing thermoplastic synthetic fibers and an in-vehicle sound absorbing material that is a laminate of a nonwoven fabric,
The base material has a sound absorbing surface that absorbs noise inside and outside the vehicle, and a crimping portion that is relatively compressed in the thickness direction relative to the sound absorbing surface,
The in-vehicle sound absorbing material has a fixing portion that is fixed to the sound absorbing surface of the base material in a state where the in-vehicle sound absorbing material is superimposed,
The fixing portion has a recess formed by pressing the in-vehicle sound absorbing material into the base material,
The recess is fixed by denaturation of at least a part of the base material and the fixing portion by ultrasonic vibration, and a displacement portion in which the depth of the recess becomes shallower toward the outer periphery is provided on the peripheral edge of the recess. A fixing structure for an in-vehicle sound absorbing material. A fixing structure for a vehicle-mounted sound absorbing material according to claim 4,
The fixing structure of the vehicle-mounted sound absorbing material, wherein the displacement portion has a convex curved surface shape that protrudes toward the side opposite to the base material.

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