KR20190039120A - Noise absorption panels for use in sound-absorbing guardrail systems - Google Patents

Abstract

The present invention relates to a noise absorbing panel for use in a sound-absorbing guardrail structure comprising a series of longitudinal guardrail beams mounted on the sides of a preferably vertically oriented support post and a guardrail structure portion facing the road Wherein the noise absorbing panel is mountable on two adjacent positioned posts.

Description

Noise absorption panels for use in sound-absorbing guardrail systems

The present invention relates to a noise absorbing panel for use in a sound absorbing guard rail system.

Guard rails are provided on the side of the road for the purpose of restricting loss of life by absorbing the energy of the vehicle that has left the road by slowing down the vehicle. In addition to these key functions, it has also been found attractive to provide noise reduction means in the guard rails.

Accordingly, one type of sound-absorbing guardrail is known as EP 1 528 158 A1. Here, the sound-absorbing panel is made of aluminum or made transparent.

Another example of a guardrail with noise reduction measures is known as WO 2010/018028 A1, wherein a perforated plate is provided behind the guardrail beam.

In order to ensure road safety and reduce the risk of personal injury, it is required that the guard rail must be able to absorb the impact of the collision without disassembly. This requirement can also be applied to noise reduction means. This requirement is to avoid scattering objects and / or sharp debris that could result in severe personal injury in the event of a collision. In guard rails with the noise reduction measures mentioned above, the case of a transparent material such as aluminum or glass or plastic is not brittle, is costly, can not withstand a vehicle impact without being broken down and scattered.

Since it is considered that the risk of disassembling the panel at the time of impact is too great, it is an object of the present invention to provide a guardrail having noise reduction means capable of withstanding the impact of a vehicle colliding with the guardrail will be.

According to the invention, this object is achieved by means of a guard rail of the kind mentioned at the outset, characterized in that the noise absorbing panel is provided with a guard rail which comprises a noise absorbing material board wrapped in an energy absorbing material with openings It is accomplished. The energy absorbing material with such openings may be formed of a mesh, a grid or a perforated material.

According to the invention, an improved sound absorbing panel can be achieved in the guardrail system by including a noise absorbing panel in, for example, an energy absorbing material such as the mesh, which also fulfills the requirements for shock absorption, Avoiding the disassembly of.

The noise absorbing material is preferably a mineral wool fibreboard having very good noise absorbing properties. However, the noise absorbing panel may also be made of a foam material, an integrated or partial rubber material, an integrated or partial plastic material, Such as other noise absorbing materials that are resistant to < RTI ID = 0.0 > a < / RTI >

In a preferred embodiment of the present invention, the energy absorbing material is a stretch metal netting surrounding the sound absorbing material board. Stretched metals or expanded metals provide very good energy absorption characteristics because netting made of stretched metal can be deformed to a large extent when impacted. Depending on the design of the stretched metal netting, it is possible to provide different stretching behaviors in the respective stress directions. For example, it is possible to provide a higher stress resistance in the longitudinal direction of the roadway than in the vertical direction in an impact situation and thus to provide a higher energy absorption. In such a direction that the stretched metal netting provides higher stress resistance, the meshes of the stretched metal netting can provide a greater amount of deformation. In such a direction that the stretched metal netting has a lower stress resistance, the meshes of the stretched metal netting deform less. This can be achieved, for example, by a rhombic mesh having a longer diagonal in the vertical direction and a shorter diagonal in the horizontal direction. Thereby, the ability of deformation of the diamond-like mesh in the horizontal direction is larger than that of deformation in the vertical direction. Under any circumstances, the destruction of the panel, especially in the event of a collision, should be avoided.

Furthermore, in addition to the mechanical behavior of the netting made of stretched metal, especially in stressed situations, such materials can also provide additional beneficial optical and / or mechanical effects. The stretched metal can provide surface structures with various groups of surfaces that are intentionally oriented in a particular direction. This makes it possible to achieve a specific optical reflection effect so that the impulse light from the vehicle is reflected in a desired direction by the surface of a particular group of netting materials while the impulse light is scattered in other less desirable directions. Also, by tilting the surface group in the preferred direction, a particular object impacting the netting material may slide along the surface of the material with less friction in a certain preferred direction, while an impacting object from another direction may experience greater friction And the like.

As an alternative to stretched metal netting, the energy absorbing material may be formed of a perforated metal sheet, a multi-slit metal sheet, a plastic net, a fiber-reinforced plastic or a rubber material, or the like.

In addition to mineral wool fiber boards, more preferably stone wool materials having very good noise absorption properties, another advantage of stone wool as a material in particular is that the material is fire resistant. An energy absorbing material, such as a stretched metal netting, may provide protection of the mineral wool and may further contribute to energy absorption upon impact due to collision with the guardrail, and an energy absorbing material, such as a stretched metal netting, Thereby ensuring that the sound-absorbing panel is not disassembled upon impact. The synergy between the noise absorbing material formed by such a mineral wool fiber board and an energy absorbing material, such as a stretched metal, is beneficial and results in an improved noise absorbing panel in the guard rail which also meets the requirements for shock absorption And avoids disassembly when colliding with a vehicle.

The term stretch metal netting refers to an expanded metal sheet produced by a process of slit and stretch. The process may include a precision die that slits and stretches the sheet material in a single operation. The whole body metal is produced by cutting and expanding a solid metal sheet in a special machine. The machine cuts and stretches the metal, bringing it to the seamless mesh without joints. The product does not include any weld joints and no woven threads, which contribute to the unique properties of the body metal. Meshes produced after the whole body of the cutting metal provide excellent transport performance to the material.

The material is then processed through a roller set to adjust the final thickness. The stretching metal of netting is a soft metal that can absorb energy by plastic deformation.

Preferably, the stretched metal is galvanized steel. This is advantageous because it is weather resistant, inexpensive to manufacture, very ductile, and deformable by deforming the mesh structure of the stretched metal netting when impacted. The sharp edges will also be rounded by galvanizing the stretched metal. However, it will be appreciated that other types of protective coatings, such as plastic coatings, paints and the like, may be used with the present invention.

As an alternative or supplement to the drawn metal, the energy absorbing mesh could be a perforated metal sheet, plastic netting, or the like, and / or a combination thereof surrounding the noise absorbing material board .

In one embodiment, netting is a panel that surrounds at least the main sides and the top side of the mineral wool fiber board. Preferably, the work surrounding the mineral wool fiber board is made by providing a mounting panel on each of the end faces, starting from a stretched metal netting panel bent in a box shape around the mineral wool fiber board.

According to the present invention, the stretched metal mesh panel can be produced by providing each of the end sections with a non-stretched area for receiving the mounting panel at each end for mounting the sound-absorbing portion to the support post Able to know. This allows the sharp edges or sharp edges of the netting structure to be avoided, thus reducing the risk of personal injury when handling the noise absorbing panel or when colliding with the guard rail. Also, since the noise absorbing panels can be installed in a city, for example a railing, the features of the present invention avoid the risk of damaging a pedestrian or a cyclist.

The noise absorbing panel is preferably about 90 cm in height and about 260 cm in length. This means that the panels can be sandwiched between posts of a common guardrail structure design. Alternatively, the panel may be positioned behind the posts as viewed in the driveway, and the pair of two consecutive posts may be disposed within a distance of about 1 m, 1.3 m, 2 m, or 4 m, respectively. However, any dimensional determination of the noise absorbing panel is contrary to the present invention. In particular, it is desirable to provide a noise absorbing panel with a predetermined standardized dimension that matches a common ready guard rail set for various applications. It can be seen by the present invention that the panel could alternatively be mounted in front of the post, i.e. between the post and the guardrail. According to one embodiment of the invention, the panels are not directly interconnected or mechanically fixed to each other. Instead, the panels are mounted on posts or guard rails and are arranged next to each other without interlocking. In other cases, the panels may be mechanically connected.

In a preferred embodiment, the sound absorbing material board, in particular the mineral wool fiber board, also has a density in the range of 60-150 kg / m3, preferably 80-120 kg / m3, more preferably 80-100 kg / m3 Can be provided. Thereby, the noise absorbing panel is provided in a size easy to handle at the time of mounting.

In one embodiment, the board is preferably provided with a protective fabric on the side facing the road. Thereby, the mineral fiber board is protected from the road salt, dust and the like. The fabric may be a weather-resistant and UV resistant fleece, i.e. a non-woven fabric, which ensures the long life of the noise absorbing panel.

In addition to this feature, it is possible to provide a structured surface with a different appearance depending on the line of sight to the protective fabric. Thereby, it is possible to provide the optical effect according to the actual visual line. For example, the fleece and thus the noise absorbing panel can reflect the incident light more strongly according to the actual incident angle. It is also possible to provide a specific light absorbing effect so that the protective fabric has a different color depending on the actual incident angle or line of light. Thus, the fleece can reflect light when illuminated from one direction of travel of the roadway, and can absorb or deflect light entirely or partially when illuminated from the other direction of travel of the roadway. In addition to the design features, this feature can also provide a functional benefit when a sound-absorbing panel is installed next to the driveway.

According to the present invention, it has been found advantageous that the sound absorbing panel is provided in either a planar or curved form. Another advantage of the stretched metal netting surrounding the mineral fiber material is that the stretched metal netting can be manually deformed so that the sound absorbing panel can be bent into the desired curved shape. Alternatively, when using panels that are stiffer and less easily bendable, shorter panels may be used for installation in the curved roadway and disposed in a polygonal path.

In one embodiment of the present invention, the guard rails are made of beams and are preferably made of steel profiles of a predetermined cross-sectional shape. The beam may include noise reduction means such as one or more puncturing sections.

As an alternative to the profile beam, the guard rail may be a tube or a wire.

According to another embodiment of the present invention, the sound absorbing panel may be provided with an end profile at each axial end portion. This end profile may have an I-shape, an H-shape, a U-shape, or a C-shape. The use of an end profile having an I-shape, H-shape allows the connection of two successive sound absorbing panels which can be introduced into the respective recesses provided by this shape profile. The U-shaped or C-shaped profile can be used as the end profile of each sound absorbing panel when no additional sound absorbing panels are connected.

According to another embodiment of the present invention, the end portions of the sound absorbing panel can be at least partially covered by the cover element. This cover element can be formed from a material having elastic deformation capability and excellent noise absorption properties, for example, from a rubber material. It is possible to fix these single elements to the energy absorbing mesh material on both sides of the noise absorbing panel, respectively. As an alternative, it is possible to provide a cover element covering the end portion of the sound absorbing panel by partially or completely surrounding or enclosing this end portion. The cover element may be secured by additional securing means or may be clamped to the noise absorbing panel. A holding rib that increases friction or provides shape fitting may be formed in the cover element to engage the noise absorbing panel and in particular the end portion of the energy absorbing mesh material. The cover element may provide a preferably resiliently deformable structural portion in the middle of the end face and the resiliently deformable structural portion may be in contact with a corresponding elastically deformable structural portion located on the opposing cover element of the adjacent sound absorbing panel . The resiliently deformable structural part can be formed by a round protrusion integrally formed in the cover, for example, with a round protruding surface. This makes it possible to compensate for tolerances when mounting or assembling the system and also to provide additional noise absorbing properties at the interface between two adjacent sound absorbing panels.

In the following, the invention will be described in more detail with reference to the accompanying drawings, which are briefly described herein.
1 is a schematic perspective view of a sound-absorbing guardrail system according to a first embodiment of the present invention.
2 is a schematic front view of a guardrail system of a first embodiment of the present invention.
3 is a side view thereof.
4 is a plan view thereof.
5 is a schematic perspective view of a sound-absorbing guardrail system according to a second embodiment of the present invention.
6 is a schematic front view thereof.
7A to 7C are a series of cross-sectional views illustrating shock absorption by a guardrail system according to the present invention.
8 to 10 are sectional views of three embodiments of a noise absorbing panel according to the present invention.
Figures 11-14 are cross-sectional views of the elements of each of the three embodiments.
15 is a detailed front view of a preferred embodiment of a drawn metal netting according to a preferred embodiment of the present invention.
16 is a side view of the stretched metal netting of Fig.
17 is a schematic perspective view of an assembly profile for use between two adjacent sound absorbing panels.
18 is a front view of a guardrail beam according to an embodiment of the present invention having a perforated region.
Figure 19 is a detailed perspective view of the beam of Figure 18;
20 is a sectional view thereof.
Figures 21 and 22 are views of a second embodiment of a guardrail beam.
Figures 23 and 24 are views of a third embodiment of a guardrail beam.
25 and 26 are two cross sectional shapes of the guardrail beam.
Figures 27 to 30 are schematic views of different perforation patterns for perforation of the guardrail beam of the present invention.
31-39 illustrate different embodiments of the design for the end element covering the end surface of the sound absorbing panel.

1 to 4, there is shown a first embodiment of a sound absorbing guardrail system according to the present invention. The guardrail system is mounted on the side or center of the road 2 and comprises a series of vertically oriented support posts 4. A series of sound absorbing panels 6 are mounted on one side of the support post 4 facing away from the road and a series of longitudinal guard rails 8 are mounted on the other side of the post 4 towards the road 2 Respectively. Between the noise absorbing panels 6, an assembly profile 14 (see FIGS. 1 and 2) is provided to ensure that the sound absorbing panel 6 is properly positioned and aligned.

The noise absorbing panel 6 includes a noise absorbing material board 10 surrounded by an energy absorbing mesh 12 (see FIG. 3).

5 and 6 show a second embodiment of a sound absorbing guardrail system according to the present invention. According to this embodiment, the guard rail 8 is provided with perforation sections 81, 82 to further increase the sound-absorbing characteristics of the guardrail system.

Figures 7a to 7c show shock absorption by the guardrail system according to the present invention. When the vehicle comes out of the road 2 and collides with the guard rail 8, the posts 4 are deflected at the height of the ground, and the noise absorbing panel 6 is moved backward, that is, , The impact energy is absorbed by this deformation of the noise absorbing panel 6. As a result, When the energy is removed by impact, the guard rail 8 is released from the post 4 as shown in Fig. 7C.

Three embodiments of the noise absorbing panel 6 are shown in Figures 8-10. Common to these three embodiments is that the noise absorbing material board 10 is enclosed within the energy absorbing mesh 12. The material of the sound absorbing material board 10 is preferably a mineral fiber wool, especially a stone wool material. The noise absorbing panel 6 made of stone wool has a guide rail system in which, when a fire occurs in relation to a road accident, regardless of whether or not there is a vehicle impact on the guide rail, Thereby contributing to the prevention of the spread of fire.

A protective profile 16, 16 ', 16 "is provided between the noise absorbing material board 10 and the energy absorbing mesh 12. In Figure 11 the noise absorbing material board 10 is shown alone, To 14 show three different designs of protection profiles 16, 16 ', 16 ". The protection profiles 16, 16 ', 16 "may be made of a transparent or opaque polymeric material such as polypropylene, polycarbonate, and the like.

As described above, the noise absorbing material board 10 is enclosed within the energy absorbing mesh 12. The mesh 12 is provided as a netting and is preferably made of stretch metal or so-called expanded metal. The netting of this whole-body metal is produced by cutting and expanding a solid metal sheet in a special machine. The machine cuts and stretches the metal, causing it to become a seamless mesh with no joints. The mesh is thereby made up of ribs 12 'and rhombic openings 12' 'as shown in Figures 15 and 16.

Mesh 12 of the full-metal metal is capable of deforming this type of mesh significantly without disruption, thereby absorbing a large amount of energy upon impact, while the noise absorbing material 10 enclosed within the mesh 12, In the case of a vehicle impact of the vehicle. The whole metal mesh is formed to be more deformable in the longitudinal direction along the road than in the vertical direction. The body metal mesh 12 is preferably bent into a shape for forming a cover for at least the top surface as well as the front and rear surfaces of the sound absorbing board 10. [ Preferably, the mesh 12 is also configured to cover at least a portion of the bottom surface of the sound absorbing board 10. [

An assembly profile 14 is provided between the noise absorbing panels 6, as described above with respect to Figs. One embodiment of the assembly profile 14 is shown in Fig. The profile 14 is made of an H-profile with two outer flanges 142 and a web flange 144 therebetween. Thereby, two receiving slots 146 are formed on the side surfaces of both sides of the web flange 144 to receive the ends of two adjacent sound absorbing panels 6. Alternatively, two U-profiles or Z-profiles may be used.

18-30, different embodiments of the guardrail beam 8 are shown. The guard rail beam 8 is formed of a bent metal sheet having a predetermined cross-sectional shape. In the embodiment shown in Figures 18-20, the guardrail beam 8 is formed with upper and lower longitudinal flange portions facing the road and a central flange portion therebetween. The upper and lower flange portions are provided with a perforated section 81, and the central flange portion is also provided with a perforated section 82. At least an end portion of the beam 8 is provided with a mounting hole 80.

21 and 22 show another embodiment of the beam design. This second design differs from the design shown in Figures 18-20 by having a non-perforated section 83 along the beam 8.

23-24, another modification of the perforation design is shown in which only the region 84 around the mounting hole 80 is not punctured.

25 and 26 are cross-sectional views of two alternative shapes of the guardrail beam 8 for the shape shown in Fig. 20, which can be used for the guardrail beam 8 facing the road in the guardrail system according to the invention Respectively.

The perforations can be provided to the guardrail beam 8 in different patterns. 27-30 illustrate different puncturing patterns.

Fig. 31 shows a detailed view of the end region of the noise absorbing panel 6 described above. In the end region of the noise absorbing panel 6, two rubber elements 200 are secured to the edge of the energy absorbing mesh material 12. Each of the rubber elements 200 provides a profile with a U-shaped containment 202 having rib-shaped protrusions 204, 206 in cross-section. In addition, each of the rubber elements 200 has a hollow elliptical ring portion 208. The rubber element 200 is secured to the free edge of the mesh material 12 by the containment portion 202 and is secured to the free edge of the mesh material 12 by ribbed protrusions 204, 206 mesh with the mesh material 12. The hollow elliptical ring portion 208, which can be elastically deformed, protrudes from the front surface 210 of the noise absorbing panel 6. Thereby, the rubber element 200 provides a sound damping and mechanical damping interface for a rough wall element or another sound absorbing panel 6 formed with the corresponding rubber element 200. In addition, the tolerance can be compensated by it.

It should be added that the noise absorbing panel 6 also shows a further protective layer 212 formed between the noise absorbing material board 10 and the energy absorbing mesh material 12. [ This additional protective layer 212 may be provided to protect the noise absorbing material board 10 from dust, water or other external influences. It can also provide optical effects such as, for example, certain reflection effects or light absorption effects according to a particular angle range. This additional protection layer may be provided in each embodiment as described above, independently of the other structural features described.

32 shows one alternative embodiment for the end cover design of the noise absorbing panel 6. Fig. A free end of the noise absorbing panel 6 is provided with a cover 220 formed of a rubber material. The cover 220 surrounds the free end of the noise absorbing panel 6 and has a bent edge region 222 that is retained in the end region of the energy absorbing mesh material 12 by resilient deformation and friction.

33 shows an embodiment of another cover 230 according to the present invention, corresponding basically to the embodiment described with reference to Fig. Figure 35 additionally shows how two opposing sound absorbing panels 6, 6 'are arranged with respect to each other with covers 230, 230', respectively. Fig. 36 additionally shows a perspective view of the cover 230. Fig. According to this embodiment, the cover 230 basically has the same shape as that shown in Fig. 32 with respect to the cover 220 and is also formed of an elastically deformable material such as rubber. In addition, the cover 230 provides a rounded protrusion 232 having a hollow interior 234 in its central region, which makes the rounded protrusion 232 resiliently deformable. The overall shape of the cover 230 is matched to the geometry of the end side of the noise absorbing panel 6 as seen in Fig. As shown in FIG. 35, two corresponding rounded protrusions 232, 232 'of each cover 230, 230', when fixed to the ends of two opposing sound absorbing panels 6, 6 ' Contact each other and provide tight engagement of the two end covers 230, 230 'under an elastic deformation. This makes it possible to compensate for the tolerances, to provide a tight connection and to provide additional noise attenuation effects at the interface between the two approximate sound absorbing panels 6, 6 '.

Fig. 34 shows another embodiment based on the embodiment according to Fig. The end cover 240 corresponds to the end cover 230 described above in its shape. That is, the end cover 240 also has a rounded protrusion 242 having a hollow interior 244. Inside the protrusion 242, a partition wall 246 extending from the inner surface of the protrusion 242 into the sound absorbing material board 10 is provided. The barrier ribs 246 further stabilize the structure of the protrusions 242.

Fig. 37 shows another embodiment based on the embodiment according to Fig. 33 also. In this embodiment, in the central region of the cover 250, the protrusions are formed by a closed ring-shaped structure 252 having a hollow interior 254 as seen in cross-section. The cover 250 may be configured such that a portion of the inner portion 256 of the closed ring-shaped structure 252 engages the front surface of the noise absorbing material board 10 by about a quarter of the circumference, Is pushed onto the end portion of the sound absorbing panel (6). This further stabilizes the cover 250 and makes it possible to compensate for the tolerances. As can be seen in Fig. 39, the shape of the cover 250 is similar to the shape already described with reference to Fig.

38, this embodiment provides a similar interface between two opposing or approximate sound absorbing panels 6, 6 ', with two ring-like structural parts 252, 252' Come into contact with each other under the required elastic deformation to provide a tight fit with favorable sound damping and cushioning properties.

In the foregoing, the invention is described with reference to several presently preferred embodiments. It is to be understood, however, that other embodiments may be provided without departing from the scope of the invention as defined in the appended claims.

Claims (17)

A noise absorbing panel for a guardrail system for installation on the side or center of a road, said guardrail system comprising a series of support posts, preferably vertically oriented, at least one noise absorbing panel mountable on said support posts, A noise absorbing panel comprising a series of longitudinal guard rails mounted on a side of a guard rail system facing the road,
Characterized in that the sound absorbing panel comprises a sound absorbing material wrapped in an energy absorbing material with openings. 2. A noise absorbing material as claimed in claim 1, characterized in that the said noise absorbing material is preferably selected from the group consisting of a board, a foamable material, an integral or partial rubber material, an integral or partial plastic material or other sound absorbing material resistant to weather conditions and abrasion action Characterized in that the sound absorbing panel is a mineral wool fiber material provided. The noise absorbing panel of claim 1 or 2, wherein the energy absorbing material with the openings comprises a mesh, a grid or a perforated material. 4. A noise absorbing panel according to any one of claims 1 to 3, wherein the energy absorbing material is a stretched metal netting surrounding the sound absorbing material board. The sound absorbing panel according to claim 4, wherein the stretched metal is a soft metal capable of absorbing energy while being plastic-deformed. The sound absorbing panel according to claim 4 or 5, wherein the stretched metal is galvanized steel. 7. A method according to any one of claims 1 to 6, characterized in that the energy absorbing material is a perforated metal sheet, plastic netting or the like surrounding the sound absorbing material board and / or a combination thereof. panel. 8. A noise absorbing panel according to any one of claims 1 to 7, wherein the netting is a panel surrounding at least the major surface and the top surface of the sound absorbing material board. 9. A method according to any one of claims 1 to 8, wherein the work of encasing the sound absorbing material comprises the steps of starting a stretched metal netting panel bent in a box shape around the sound absorbing material board, Wherein the sound absorbing panel is made of a synthetic resin. 10. A method according to any one of claims 1 to 9, wherein the work surrounding the noise absorbing material begins with a stretched metal netting panel cast with a sound insulating material by a wet-felt process, Characterized in that a mounting panel is provided on each of the end faces of the stretched metal netting panel. 11. The stretched metal mesh panel according to any one of claims 1 to 10, wherein each of the end sections has a non-stretched region for receiving the mounting panel at each end for mounting the sound-absorbing portion to the support post Wherein the sound absorbing panel is manufactured by a method of manufacturing a sound absorbing panel. 12. A sound absorbing panel as claimed in any one of the preceding claims, wherein the sound absorbing panel is approximately 90 cm in height, approximately 130 cm in length, approximately 260 cm, approximately 520 cm or approximately 530 cm. 13. The mineral wool fiber board according to any one of claims 1 to 12, wherein the mineral wool fiber board is a stone wool and has a density of 60-150 kg / m3, preferably 80-120 kg / m3, more preferably 80-100 kg / Lt; RTI ID = 0.0 > m3. ≪ / RTI > 14. A noise absorbing panel according to any of the preceding claims, characterized in that the board is preferably provided with a protective fabric on the side facing the road. 15. The sound absorbing panel of claim 14, wherein the protective fabric has a structured surface having a different appearance depending on the actual line of sight. 16. The sound absorbing panel according to any one of claims 1 to 15, wherein the sound absorbing panel is provided in a planar shape or a curved or polygonal shape. 17. A sound absorbing panel according to any one of the preceding claims, wherein the sound absorbing panel has an end profile at each axial end portion, the end profile having an I-shape, an H-shape, a U- Wherein the sound absorbing panel is made of a metal.

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