EP3115124A1 - Frp plate fastening structure - Google Patents

Frp plate fastening structure Download PDF

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Publication number
EP3115124A1
EP3115124A1 EP14889773.9A EP14889773A EP3115124A1 EP 3115124 A1 EP3115124 A1 EP 3115124A1 EP 14889773 A EP14889773 A EP 14889773A EP 3115124 A1 EP3115124 A1 EP 3115124A1
Authority
EP
European Patent Office
Prior art keywords
washer
frp plate
frp
main body
metal
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP14889773.9A
Other languages
German (de)
French (fr)
Inventor
Steffen Jahn
Christoph Kerkeling
Sven Leonhardt
Artur Poeppel
Anna RANDON-VITANOVA
Shotaro Ayuzawa
Yuta Urushiyama
Tomoya YABU
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Honda Motor Co Ltd
Original Assignee
Honda Motor Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Honda Motor Co Ltd filed Critical Honda Motor Co Ltd
Publication of EP3115124A1 publication Critical patent/EP3115124A1/en
Withdrawn legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D39/00—Application of procedures in order to connect objects or parts, e.g. coating with sheet metal otherwise than by plating; Tube expanders
    • B21D39/03—Application of procedures in order to connect objects or parts, e.g. coating with sheet metal otherwise than by plating; Tube expanders of sheet metal otherwise than by folding
    • B21D39/034—Joining superposed plates by piercing
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D41/00—Application of procedures in order to alter the diameter of tube ends
    • B21D41/02—Enlarging
    • B21D41/026—Enlarging by means of mandrels

Definitions

  • the present invention relates to a securing structure for an FRP plate in which a metal grommet is fixed to an FRP plate and the FRP plate is secured to a secured member by screwing a nut onto a bolt extending through the metal grommet and the secured member.
  • Patent Document 1 German Patent No. 10 2009 013 265 B4
  • part of the metal plate that has been deformed into a collar shape with the rotating tool becomes thin, and when the projecting portion at the extremity of the thin portion is press formed into a washer shape, the thickness further decreases, a crack occurs, the tightening force of a bolt extending through the metal grommet cannot be supported by the collar portion and the washer portion, which are thin, deformation occurs, and there is a possibility that this will cause damage to the FRP plate.
  • the present invention has been accomplished in light of the above circumstances, and it is an object thereof to provide a metal grommet that can easily be produced and can strongly fix an FRP plate.
  • a securing structure for an FRP plate in which a metal grommet is fixed to an FRP plate, and the FRP plate is secured to a secured member by screwing a nut onto a bolt extending through the metal grommet and the secured member, wherein the metal grommet comprises a grommet main body and a washer, the grommet main body comprises a washer portion that abuts against one surface of the FRP plate and a collar portion that is formed integrally with the washer portion and is fitted into a through hole of the FRP plate, and the washer is latched onto an extremity of the collar portion and abuts against the other surface of the FRP plate.
  • the washer is latched by means of a swaged portion formed by swaging the extremity of the collar portion.
  • a thickness of the swaged portion is substantially the same as a thickness of the collar portion.
  • a taper portion is formed in advance on an inner periphery of the washer, the taper portion increasing in diameter in a direction going away from the grommet main body.
  • a swaging tool for swaging the collar portion comprises a flat portion that abuts against the washer and a taper portion that protrudes from the flat portion so as to be tapered and fits within the collar portion.
  • the grommet main body is formed by extending a rotating tool having a sharp extremity through a metal plate and the FRP plate in a state in which the metal plate is superimposed on one surface of the FRP plate.
  • a pilot hole is formed in advance in the metal plate, and the extremity of the rotating tool is pressed against the center of the pilot hole and extended therethrough.
  • an excess portion that protrudes from the extremity of the collar portion due to the rotating tool being extended therethrough is cut off prior to a swaging step.
  • the washer portion and the washer have an annular form.
  • the FRP plate is an automobile part made of FRP
  • the secured member is an automobile frame made of metal.
  • the metal grommet is fixed to the FRP plate, and the FRP plate is secured to the secured member by screwing the nut onto the bolt extending through the metal grommet and the secured member.
  • the metal grommet includes the grommet main body and the washer
  • the grommet main body includes the washer portion abutting against one surface of the FRP plate and the collar portion formed integrally with the washer portion and fitted into the through hole of the FRP plate, and the washer is latched onto the extremity of the collar portion and abuts against the other surface of the FRP plate, it is unnecessary to integrally mold the washer by stretching the collar portion of the grommet main body, the thickness of the collar portion can be maintained by an amount corresponding thereto, thus enhancing the strength, and it is possible to prevent the thickness of the portion corresponding to the washer from decreasing, a crack from occurring, and the strength from deteriorating.
  • the area around the through hole of the FRP plate is sandwiched between the washer portion of the grommet main body and the washer, which is a separate member, and it is thus possible to suppress the progress of detachment of fibers of the FRP plate and enhance the durability.
  • the washer is latched by means of the swaged portion formed by swaging the extremity of the collar portion, it is possible to strongly integrate, by means of a simple structure, the grommet main body and the washer, which are formed from separate members.
  • the thickness of the swaged portion is substantially the same as the thickness of the collar portion, it is possible to ensure the strength of the swaged portion and support the tightening force of the bolt.
  • the taper portion which increases in diameter in a direction going away from the grommet main body, is formed in advance on the inner periphery of the washer, it is possible to enhance the strength of the swaged portion joining the extremity of the collar portion of the grommet main body and the washer.
  • the swaging tool for swaging the collar portion includes the flat portion abutting against the washer and the taper portion protruding from the flat portion so as to be tapered and fitting within the collar portion, not only is it possible to swage effectively the extremity of the collar portion by means of the taper portion, but it is also possible to finish the latching part between the washer and the collar portion so that it is flat by means of the flat portion, thus enhancing the precision of machining.
  • the grommet main body is formed by extending the rotating tool having a sharp extremity through the metal plate and the FRP plate in a state in which the metal plate is superimposed on one surface of the FRP plate, not only is it possible to simply produce the grommet main body integrally including the washer portion and the collar portion from the metal plate, but it is also possible to machine the through hole of the FRP plate at the same time, and moreover it is not necessary to employ a step of assembling the grommet main body to the FRP plate.
  • the pilot hole is formed in advance in the metal plate, and the tip of the rotating tool is pressed against the center of the pilot hole and extended therethrough, it is possible to prevent excessive stress from acting on the metal plate, which causes cracks, thereby enabling the grommet main body to be machined with good precision.
  • the washer portion and the washer have an annular form, it is possible to evenly disperse the tightening force of the bolt throughout the FRP plate.
  • the FRP plate is an automobile part made of an FRP
  • the secured member is an automobile frame made of metal
  • FIG. 1 to FIG. 6 An embodiment of the present invention is explained below by reference to FIG. 1 to FIG. 6 .
  • a metal grommet 14 made of iron or an aluminum alloy is fitted into an FRP (fiber-reinforced plastic) plate 13 formed by solidifying continuous fibers 11 formed from carbon fibers or glass fibers aligned in one direction using a matrix resin 12, and by screwing a nut 17 onto a bolt 16 extending through a secured member 15 such as a steel plate, for example, and the metal grommet 14, the FRP plate 13 is secured to the metal plate 15.
  • FRP fiber-reinforced plastic
  • the metal grommet 14 is formed by joining two members, that is, a grommet main body 18 and a washer 19; the grommet main body 18 includes a collar portion 18b extending cylindrically from the center of an annular washer portion 18a, and in a state in which the washer portion 18a abuts against one surface of the FRP plate 13 the collar portion 18b extends through a circular through hole 13a of the FRP plate 13 and the extremity thereof projects from the other surface of the FRP plate 13.
  • the washer 19 is an annular member having substantially the same shape as that of the washer portion 18a of the grommet main body 18, and a taper portion 19a that increases in diameter in a direction going away from the grommet main body 18 is formed on the inner periphery of the washer 19.
  • the washer 19 is fitted onto the extremity of the collar portion 18b of the grommet main body 18 in a state in which it abuts against the other surface of the FRP plate 13, and is integrally joined by means of a swaged portion 18
  • a method for producing the metal grommet 14 is now explained by reference to FIG. 2 to FIG. 4 .
  • a disk-shaped metal plate 20 which is a material for the grommet main body 18, is superimposed on one surface of the FRP plate 13.
  • a circular pilot hole 20a is concentrically formed in advance in the metal plate 20.
  • the metal plate 20 around the pilot hole 20a is bored and pushed and widened in a cylindrical shape to thus form the collar portion 18b, and the washer portion 18a is formed in the remaining portion of the metal plate 20.
  • the matrix resin of the FRP plate 13 is softened by the frictional heat generated, and the continuous fibers 11 aligned in one direction move so as to bypass the outer periphery of the grommet main body 18, thus enabling the through hole 13a to be formed in the FRP plate 13 without degrading the strength by breaking the continuous fibers 11 (see FIG. 2 (B) ).
  • a thickness t of the collar portion 18b of the grommet main body 18 coincides substantially with a thickness t of the swaged portion 18c (see FIG. 1 ).
  • the grommet main body 18 is formed from the washer portion 18a abutting against one surface of the FRP plate 13 and the collar portion 18b formed integrally with the washer portion 18a and fitted into the through hole 13b of the FRP plate 13, and the washer 19 is latched onto the extremity of the collar portion 18b and abuts against the other surface of the FRP plate 13, the area around the through hole 13a of the FRP plate 13 is sandwiched between the washer portion 18a of the grommet main body 18 and the washer 19, which is a separate member, thereby suppressing the progress of detachment of the continuous fibers 11 of the FRP plate 13 and enhancing the durability.
  • the washer portion 18a of the grommet main body 18 and the washer 19 have an annular shape, it is possible to
  • the grommet main body 18 and the washer 19 are formed from separate members, when the grommet main body 18 is shaped by means of the rotating tool 21, it is not necessary to stretch the collar portion 18b and mold the washer 19 as a unit, and not only is it possible to enhance the strength by ensuring the thickness of the collar portion 18b by an amount corresponding thereto, but it is also possible to prevent cracks from occurring and the strength from deteriorating due to the thickness of the portion corresponding to the washer 19 becoming small.
  • the washer 19 is latched onto the extremity of the collar portion 18b by swaging, it is possible to strongly integrate the grommet main body 18 and the washer 19, which are formed from separate members, with a simple structure. Moreover, since the thickness t of the swaged extremity of the collar portion 18b is substantially equal to the thickness t of the washer 19 (see FIG. 1 ), the strength of the swaged portion 18c is ensured, and the tightening force of the bolt 16 can be supported.
  • the swaging tool 23 for swaging the extremity of the collar portion 18b includes the flat portion 23a abutting against the washer 19 and the taper portion 23b protruding from the flat portion 23a so as to be tapered and fitting within the collar portion 18b, not only is it possible to swage effectively the extremity of the collar portion 18b by means of the taper portion 23b, but it is also possible to finish the swaged portion 18c between the washer 19 and the collar portion 18b so that it is flat by means of the flat portion 23a, thus enhancing the precision of machining.
  • the grommet main body 18 is formed by extending the rotating tool 21 having a sharp extremity through the metal plate 20 and the FRP plate 13 in a state in which the metal plate 20 is superimposed on one surface of the FRP plate 13, not only is it possible to simply produce from the metal plate 20 the grommet main body 18 integrally having the washer portion 18a and the collar portion 18b, but it is also possible to machine the through hole 13 a of the FRP plate 13 at the same time and, moreover, it is unnecessary to employ a step of assembling the grommet main body 18 to the FRP plate 13.
  • the pilot hole 20a is formed in advance in the metal plate 20, and the extremity of the rotating tool 21 is pressed against and extended through the center of the pilot hole 20a, it is possible to prevent excessive stress from acting on the metal plate 20 to thus cause cracks, and the grommet main body 18 can be machined with good precision. Furthermore, since the excess portion 18e (see FIG. 3 (A) ), which is made to protrude from the extremity of the collar portion 18b by extending the rotating tool 21 therethrough, is cut off before the swaging step, it is possible to finish the latching portion 18c by swaging the washer 19 and the collar portion 18b with good precision.
  • FIG. 5 and FIG. 6 show an example in which the present invention is applied to an automobile vehicle body.
  • the secured member 15 formed from a flat metal plate is welded to front ends of a pair of left and right front side frames 24 disposed in the fore-and-aft direction in a front part of the vehicle body in order to support an engine or a transmission, and the front end of a lower member 25 extending downward to the front from a front pillar upper, which is not illustrated, is welded on the outside in the vehicle width direction of the secured member 15.
  • An FRP bumper beam extension 26 connecting an end part in the vehicle width direction of a bumper beam, which is not illustrated, and the secured member 15 includes front side flanges 26a and 26a connected to the bumper beam and rear side flanges 26b and 26b connected to the secured member 15.
  • the rear side flanges 26b and 26b correspond to the FRP plate 13 of the present invention, and six metal grommets 14 fitted thereinto are secured to the secured member 15 by means of the bolts 16 and the nuts 17.
  • the FRP plate 13 forming part of the FRP automobile bumper beam extension 26 is secured to the secured member 15 forming part of the automobile metal frame via the metal grommets 14, it is possible to strongly secure the FRP part to the metal frame while achieving a light weight by replacing a conventional metal part with an FRP part.
  • pilot hole 20a of the metal plate 20 it is not always necessary to employ the pilot hole 20a of the metal plate 20, and a metal plate 20 having no pilot hole 20a may be bored directly.

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  • Mechanical Engineering (AREA)
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Abstract

Since a metal grommet (14) includes a grommet main body (18) and a washer (19), the grommet main body (18) includes a washer portion (18a) abutting against one surface of a FRP plate (13) and a collar portion (18b) formed integrally with the washer portion (18a) and fitted into a through hole (13a) of the FRP plate (13), and the washer (19) is latched onto an extremity of the collar portion (18b) and abuts against the other surface of the FRP plate (13), it is unnecessary to integrally mold the washer (19) by stretching the collar portion (18b) of the grommet main body (18), the thickness of the collar portion (18b) can be maintained by an amount corresponding thereto, thus enhancing the strength, and while preventing the thickness of the portion corresponding to the washer (19) from decreasing, a crack from occurring, and the strength from deteriorating, the area around the through hole (13a) of the FRP plate is sandwiched between the washer portion (18a) of the grommet main body (18) and the washer (19), which is a separate member, and it is thus possible to suppress the progress of detachment of fibers of the FRP plate (13) and enhance the durability.

Description

    TECHNICAL FIELD
  • The present invention relates to a securing structure for an FRP plate in which a metal grommet is fixed to an FRP plate and the FRP plate is secured to a secured member by screwing a nut onto a bolt extending through the metal grommet and the secured member.
    • BACKGROUND ART
  • An arrangement in which, at the same time as producing a metal grommet having a pair of washer portions connected to opposite ends of a collar portion, in order to mount the metal grommet on an FRP plate, a metal plate and the FRP plate are bored using a rotating tool having a sharp extremity in a state in which the metal plate is superimposed on one surface of the FRP plate, part of the metal plate is thereby deformed into a collar shape and made to project from the other surface of the FRP plate, and subsequently the projecting portion is press formed into a flat washer shape is known from Patent Document 1 below.
    • RELATED ART DOCUMENTS PATENT DOCUMENTS
  • Patent Document 1: German Patent No. 10 2009 013 265 B4
    • SUMMARY OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION
  • However, in the above arrangement, part of the metal plate that has been deformed into a collar shape with the rotating tool becomes thin, and when the projecting portion at the extremity of the thin portion is press formed into a washer shape, the thickness further decreases, a crack occurs, the tightening force of a bolt extending through the metal grommet cannot be supported by the collar portion and the washer portion, which are thin, deformation occurs, and there is a possibility that this will cause damage to the FRP plate.
  • The present invention has been accomplished in light of the above circumstances, and it is an object thereof to provide a metal grommet that can easily be produced and can strongly fix an FRP plate.
    • MEANS FOR SOLVING THE PROBLEMS
  • In order to attain the above object, according to a first aspect of the present invention, there is provided a securing structure for an FRP plate in which a metal grommet is fixed to an FRP plate, and the FRP plate is secured to a secured member by screwing a nut onto a bolt extending through the metal grommet and the secured member, wherein the metal grommet comprises a grommet main body and a washer, the grommet main body comprises a washer portion that abuts against one surface of the FRP plate and a collar portion that is formed integrally with the washer portion and is fitted into a through hole of the FRP plate, and the washer is latched onto an extremity of the collar portion and abuts against the other surface of the FRP plate.
  • Further, according to a second aspect of the present invention, in addition to the first aspect, the washer is latched by means of a swaged portion formed by swaging the extremity of the collar portion.
  • Furthermore, according to a third aspect of the present invention, in addition to the second aspect, a thickness of the swaged portion is substantially the same as a thickness of the collar portion.
  • Moreover, according to a fourth aspect of the present invention, in addition to the second or third aspect, a taper portion is formed in advance on an inner periphery of the washer, the taper portion increasing in diameter in a direction going away from the grommet main body.
  • Further, according to a fifth aspect of the present invention, in addition to any one of the second to fourth aspects, a swaging tool for swaging the collar portion comprises a flat portion that abuts against the washer and a taper portion that protrudes from the flat portion so as to be tapered and fits within the collar portion.
  • Furthermore, according to a sixth aspect of the present invention, in addition to any one of the first to fifth aspects, the grommet main body is formed by extending a rotating tool having a sharp extremity through a metal plate and the FRP plate in a state in which the metal plate is superimposed on one surface of the FRP plate.
  • Moreover, according to a seventh aspect of the present invention, in addition to the sixth aspect, a pilot hole is formed in advance in the metal plate, and the extremity of the rotating tool is pressed against the center of the pilot hole and extended therethrough.
  • Further, according to an eighth aspect of the present invention, in addition to the sixth or seventh aspect, an excess portion that protrudes from the extremity of the collar portion due to the rotating tool being extended therethrough is cut off prior to a swaging step.
  • Furthermore, according to a ninth aspect of the present invention, in addition to any one of the first to eighth aspects, the washer portion and the washer have an annular form.
  • Moreover, according to a tenth aspect of the present invention, in addition to any one of the first to ninth aspects, the FRP plate is an automobile part made of FRP, and the secured member is an automobile frame made of metal.
    • EFFECTS OF THE INVENTION
  • In accordance with the first aspect of the present invention, the metal grommet is fixed to the FRP plate, and the FRP plate is secured to the secured member by screwing the nut onto the bolt extending through the metal grommet and the secured member. Since the metal grommet includes the grommet main body and the washer, the grommet main body includes the washer portion abutting against one surface of the FRP plate and the collar portion formed integrally with the washer portion and fitted into the through hole of the FRP plate, and the washer is latched onto the extremity of the collar portion and abuts against the other surface of the FRP plate, it is unnecessary to integrally mold the washer by stretching the collar portion of the grommet main body, the thickness of the collar portion can be maintained by an amount corresponding thereto, thus enhancing the strength, and it is possible to prevent the thickness of the portion corresponding to the washer from decreasing, a crack from occurring, and the strength from deteriorating. Moreover, the area around the through hole of the FRP plate is sandwiched between the washer portion of the grommet main body and the washer, which is a separate member, and it is thus possible to suppress the progress of detachment of fibers of the FRP plate and enhance the durability.
  • Furthermore, in accordance with the second aspect of the present invention, since the washer is latched by means of the swaged portion formed by swaging the extremity of the collar portion, it is possible to strongly integrate, by means of a simple structure, the grommet main body and the washer, which are formed from separate members.
  • Moreover, in accordance with the third aspect of the present invention, since the thickness of the swaged portion is substantially the same as the thickness of the collar portion, it is possible to ensure the strength of the swaged portion and support the tightening force of the bolt.
  • Furthermore, in accordance with the fourth aspect of the present invention, since the taper portion, which increases in diameter in a direction going away from the grommet main body, is formed in advance on the inner periphery of the washer, it is possible to enhance the strength of the swaged portion joining the extremity of the collar portion of the grommet main body and the washer.
  • Moreover, in accordance with the fifth aspect of the present invention, since the swaging tool for swaging the collar portion includes the flat portion abutting against the washer and the taper portion protruding from the flat portion so as to be tapered and fitting within the collar portion, not only is it possible to swage effectively the extremity of the collar portion by means of the taper portion, but it is also possible to finish the latching part between the washer and the collar portion so that it is flat by means of the flat portion, thus enhancing the precision of machining.
  • Furthermore, in accordance with the sixth aspect of the present invention, since the grommet main body is formed by extending the rotating tool having a sharp extremity through the metal plate and the FRP plate in a state in which the metal plate is superimposed on one surface of the FRP plate, not only is it possible to simply produce the grommet main body integrally including the washer portion and the collar portion from the metal plate, but it is also possible to machine the through hole of the FRP plate at the same time, and moreover it is not necessary to employ a step of assembling the grommet main body to the FRP plate.
  • Moreover, in accordance with the seventh aspect of the present invention, since the pilot hole is formed in advance in the metal plate, and the tip of the rotating tool is pressed against the center of the pilot hole and extended therethrough, it is possible to prevent excessive stress from acting on the metal plate, which causes cracks, thereby enabling the grommet main body to be machined with good precision.
  • Furthermore, in accordance with the eighth aspect of the present invention, since the excess portion protruding from the extremity of the collar portion due to the rotating tool being extended therethrough is cut off prior to the swaging step, it is possible to finish the swaged portion, via which the washer and the collar portion latch, with good precision.
  • Moreover, in accordance with the ninth aspect of the present invention, since the washer portion and the washer have an annular form, it is possible to evenly disperse the tightening force of the bolt throughout the FRP plate.
  • Furthermore, in accordance with the tenth aspect of the present invention, since the FRP plate is an automobile part made of an FRP, and the secured member is an automobile frame made of metal, it is possible to strongly secure the part made of an FRP to the frame made of metal while lightening the weight by replacing a conventional metal part with an FRP part.
    • BRIEF DESCRIPTION OF DRAWINGS
    • [FIG. 1] FIG. 1 is a diagram showing a state in which an FRP plate having a metal grommet fitted thereinto is secured to a secured member. (first embodiment)
    • [FIG. 2] FIG. 2 is a diagram for explaining a step of boring a metal plate and an FRP plate. (first embodiment)
    • [FIG. 3] FIG. 3 is a diagram for explaining a step of cutting off the metal grommet. (first embodiment)
    • [FIG. 4] FIG. 4 is a diagram for explaining a step of swaging the metal grommet. (first embodiment)
    • [FIG. 5] FIG. 5 is a diagram showing an example in which the present invention is applied to an automobile vehicle body. (first embodiment)
    • [FIG. 6] FIG. 6 is a sectional view along line 6-6 in FIG. 5. (first embodiment)
    EXPLANATION OF REFERENCE NUMERALS AND SYMBOLS
    • 13
    FRP plate
    13a
    Through hole
    14
    Metal grommet
    15
    Secured member
    16
    Bolt
    17
    Nut
    18
    Grommet main body
    18a
    Washer portion
    18b
    Collar portion
    18c
    Swaged portion
    18e
    Excess portion
    19
    Washer
    19a
    Taper portion
    20
    Metal plate
    20a
    Pilot hole
    21
    Rotating tool
    23
    Swaging tool
    23a
    Flat portion
    23b
    Taper portion
    BEST MODE FOR CARRYING OUT THE INVENTION
  • An embodiment of the present invention is explained below by reference to FIG. 1 to FIG. 6.
    • FIRST EMBODIMENT
  • As shown in FIG. 1, a metal grommet 14 made of iron or an aluminum alloy is fitted into an FRP (fiber-reinforced plastic) plate 13 formed by solidifying continuous fibers 11 formed from carbon fibers or glass fibers aligned in one direction using a matrix resin 12, and by screwing a nut 17 onto a bolt 16 extending through a secured member 15 such as a steel plate, for example, and the metal grommet 14, the FRP plate 13 is secured to the metal plate 15.
  • The metal grommet 14 is formed by joining two members, that is, a grommet main body 18 and a washer 19; the grommet main body 18 includes a collar portion 18b extending cylindrically from the center of an annular washer portion 18a, and in a state in which the washer portion 18a abuts against one surface of the FRP plate 13 the collar portion 18b extends through a circular through hole 13a of the FRP plate 13 and the extremity thereof projects from the other surface of the FRP plate 13. The washer 19 is an annular member having substantially the same shape as that of the washer portion 18a of the grommet main body 18, and a taper portion 19a that increases in diameter in a direction going away from the grommet main body 18 is formed on the inner periphery of the washer 19. The washer 19 is fitted onto the extremity of the collar portion 18b of the grommet main body 18 in a state in which it abuts against the other surface of the FRP plate 13, and is integrally joined by means of a swaged portion 18c.
  • A method for producing the metal grommet 14 is now explained by reference to FIG. 2 to FIG. 4.
  • As shown in FIG. 2 (A), a disk-shaped metal plate 20, which is a material for the grommet main body 18, is superimposed on one surface of the FRP plate 13. In this process, a circular pilot hole 20a is concentrically formed in advance in the metal plate 20. Subsequently, when a rotating tool 21 having a conical sharp extremity is inserted into the center of the pilot hole 20a while rotating, as shown in FIG. 2 (B) the metal plate 20 around the pilot hole 20a is bored and pushed and widened in a cylindrical shape to thus form the collar portion 18b, and the washer portion 18a is formed in the remaining portion of the metal plate 20. At the same time as this, the FRP plate 13 that has been bored by means of the rotating tool 21 is pushed and widened by means of the collar portion 18b, and the through hole 13a into which the collar portion 18b is fitted is thus formed. A thin excess portion 18e projects from the extremity of the collar portion 18b extending through the FRP plate 13.
  • When the metal plate 20 and the FRP plate 13 are subjected to boring with the rotating tool 21, the matrix resin of the FRP plate 13 is softened by the frictional heat generated, and the continuous fibers 11 aligned in one direction move so as to bypass the outer periphery of the grommet main body 18, thus enabling the through hole 13a to be formed in the FRP plate 13 without degrading the strength by breaking the continuous fibers 11 (see FIG. 2 (B)).
  • Subsequently, as shown in FIG. 3 (A), after the thin excess portion 18e projecting from the extremity of the collar portion 18b extending through the FRP plate 13 is cut off, as shown in FIG. 3 (B), the washer 19, which is a separate member, is fitted onto the extremity of the collar portion 18b of the grommet main body 18.
  • Subsequently, as shown in FIG. 4 (A), in a state in which the washer portion 18a of the grommet main body 18 is supported on a receiving member 22, the extremity of the collar portion 18b is swaged by means of a swaging tool 23. Formed on the extremity of the swaging tool 23 are a flat portion 23a and a frustoconical taper portion 23b projecting from the flat portion 23a; the flat portion 23a abuts against the washer 19, and the taper portion 23b abuts against and swages the extremity of the collar portion 18b of the grommet main body 18, thus forming the swaged portion 18c, which is plastically deformed, on the radially outer side of the extremity of the collar portion 18b, and thereby integrally joining the washer 19 to the grommet main body 18. In a state in which swaging is completed, a thickness t of the collar portion 18b of the grommet main body 18 coincides substantially with a thickness t of the swaged portion 18c (see FIG. 1).
  • The operation of the embodiment of the present invention having the above arrangement is now explained.
  • When the FRP plate 13 is secured to the secured member 15 by means of the bolt 16 and the nut 17, since the metal grommet 14 mounted on the FRP plate 13 and having the bolt 16 extending therethrough is formed from the grommet main body 18 and the washer 19, the grommet main body 18 is formed from the washer portion 18a abutting against one surface of the FRP plate 13 and the collar portion 18b formed integrally with the washer portion 18a and fitted into the through hole 13b of the FRP plate 13, and the washer 19 is latched onto the extremity of the collar portion 18b and abuts against the other surface of the FRP plate 13, the area around the through hole 13a of the FRP plate 13 is sandwiched between the washer portion 18a of the grommet main body 18 and the washer 19, which is a separate member, thereby suppressing the progress of detachment of the continuous fibers 11 of the FRP plate 13 and enhancing the durability. In this process, since the washer portion 18a of the grommet main body 18 and the washer 19 have an annular shape, it is possible to disperse the tightening force of the bolt 16 evenly throughout the FRP plate 13.
  • Moreover, since the grommet main body 18 and the washer 19 are formed from separate members, when the grommet main body 18 is shaped by means of the rotating tool 21, it is not necessary to stretch the collar portion 18b and mold the washer 19 as a unit, and not only is it possible to enhance the strength by ensuring the thickness of the collar portion 18b by an amount corresponding thereto, but it is also possible to prevent cracks from occurring and the strength from deteriorating due to the thickness of the portion corresponding to the washer 19 becoming small.
  • Furthermore, since the washer 19 is latched onto the extremity of the collar portion 18b by swaging, it is possible to strongly integrate the grommet main body 18 and the washer 19, which are formed from separate members, with a simple structure. Moreover, since the thickness t of the swaged extremity of the collar portion 18b is substantially equal to the thickness t of the washer 19 (see FIG. 1), the strength of the swaged portion 18c is ensured, and the tightening force of the bolt 16 can be supported. In this process, since the taper portion 19a, which increases in diameter in a direction going away from the grommet main body 18, is formed in advance on the inner periphery of the washer 19, it is possible to enhance the strength of the swaged portion 18c joining the extremity of the collar portion 18b and the washer 19.
  • Moreover, since the swaging tool 23 for swaging the extremity of the collar portion 18b includes the flat portion 23a abutting against the washer 19 and the taper portion 23b protruding from the flat portion 23a so as to be tapered and fitting within the collar portion 18b, not only is it possible to swage effectively the extremity of the collar portion 18b by means of the taper portion 23b, but it is also possible to finish the swaged portion 18c between the washer 19 and the collar portion 18b so that it is flat by means of the flat portion 23a, thus enhancing the precision of machining.
  • Furthermore, since in the step of producing the metal grommet 14, the grommet main body 18 is formed by extending the rotating tool 21 having a sharp extremity through the metal plate 20 and the FRP plate 13 in a state in which the metal plate 20 is superimposed on one surface of the FRP plate 13, not only is it possible to simply produce from the metal plate 20 the grommet main body 18 integrally having the washer portion 18a and the collar portion 18b, but it is also possible to machine the through hole 13 a of the FRP plate 13 at the same time and, moreover, it is unnecessary to employ a step of assembling the grommet main body 18 to the FRP plate 13.
  • In this process, since the pilot hole 20a is formed in advance in the metal plate 20, and the extremity of the rotating tool 21 is pressed against and extended through the center of the pilot hole 20a, it is possible to prevent excessive stress from acting on the metal plate 20 to thus cause cracks, and the grommet main body 18 can be machined with good precision. Furthermore, since the excess portion 18e (see FIG. 3 (A)), which is made to protrude from the extremity of the collar portion 18b by extending the rotating tool 21 therethrough, is cut off before the swaging step, it is possible to finish the latching portion 18c by swaging the washer 19 and the collar portion 18b with good precision.
  • FIG. 5 and FIG. 6 show an example in which the present invention is applied to an automobile vehicle body.
  • The secured member 15 formed from a flat metal plate is welded to front ends of a pair of left and right front side frames 24 disposed in the fore-and-aft direction in a front part of the vehicle body in order to support an engine or a transmission, and the front end of a lower member 25 extending downward to the front from a front pillar upper, which is not illustrated, is welded on the outside in the vehicle width direction of the secured member 15. An FRP bumper beam extension 26 connecting an end part in the vehicle width direction of a bumper beam, which is not illustrated, and the secured member 15 includes front side flanges 26a and 26a connected to the bumper beam and rear side flanges 26b and 26b connected to the secured member 15. The rear side flanges 26b and 26b correspond to the FRP plate 13 of the present invention, and six metal grommets 14 fitted thereinto are secured to the secured member 15 by means of the bolts 16 and the nuts 17.
  • As described above, since the FRP plate 13 forming part of the FRP automobile bumper beam extension 26 is secured to the secured member 15 forming part of the automobile metal frame via the metal grommets 14, it is possible to strongly secure the FRP part to the metal frame while achieving a light weight by replacing a conventional metal part with an FRP part.
  • An embodiment of the present invention is explained above, but the present invention may be modified in a variety of ways as long as the modifications do not depart from the spirit and scope thereof.
  • For example, it is not always necessary to employ the pilot hole 20a of the metal plate 20, and a metal plate 20 having no pilot hole 20a may be bored directly.
  • Furthermore, if the excess portion 18e formed when molding the grommet main body 18 by means of the rotating tool 21 is small, it is not always necessary to cut off the excess portion 18e.

Claims (10)

  1. A securing structure for an FRP plate in which a metal grommet (14) is fixed to an FRP plate (13), and the FRP plate (13) is secured to a secured member (15) by screwing a nut (17) onto a bolt (16) extending through the metal grommet (14) and the secured member (15), wherein
    the metal grommet (14) comprises a grommet main body (18) and a washer (19), the grommet main body (18) comprises a washer portion (18a) that abuts against one surface of the FRP plate (13) and a collar portion (18b) that is formed integrally with the washer portion (18a) and is fitted into a through hole (13a) of the FRP plate (13), and the washer (19) is latched onto an extremity of the collar portion (18b) and abuts against the other surface of the FRP plate (13).
  2. The securing structure for an FRP plate according to Claim 1, wherein the washer (19) is latched by means of a swaged portion (18c) formed by swaging the extremity of the collar portion (18b).
  3. The securing structure for an FRP plate according to Claim 2, wherein a thickness of the swaged portion (18c) is substantially the same as a thickness of the collar portion (18b).
  4. The securing structure for an FRP plate according to Claim 2 or Claim 3, wherein a taper portion (19a) is formed in advance on an inner periphery of the washer (19), the taper portion (19a) increasing in diameter in a direction going away from the grommet main body (18).
  5. The securing structure for an FRP plate according to any one of Claim 2 to Claim 4, wherein a swaging tool (23) for swaging the collar portion (18b) comprises a flat portion (23 a) that abuts against the washer (19) and a taper portion (23b) that protrudes from the flat portion (23 a) so as to be tapered and fits within the collar portion (18b).
  6. The securing structure for an FRP plate according to any one of Claim 1 to Claim 5, wherein the grommet main body (18) is formed by extending a rotating tool (21) having a sharp extremity through a metal plate (20) and the FRP plate (13) in a state in which the metal plate (20) is superimposed on one surface of the FRP plate (13).
  7. The securing structure for an FRP plate according to Claim 6, wherein a pilot hole (20a) is formed in advance in the metal plate (20), and the extremity of the rotating tool (21) is pressed against the center of the pilot hole (20a) and extended therethrough.
  8. The securing structure for an FRP plate according to Claim 6 or Claim 7, wherein an excess portion (18e) that protrudes from the extremity of the collar portion (18b) due to the rotating tool (21) being extended therethrough is cut off prior to a swaging step.
  9. The securing structure for an FRP plate according to any one of Claim 1 to Claim 8, wherein the washer portion (18a) and the washer (19) have an annular form.
  10. The securing structure for an FRP plate according to any one of Claim 1 to Claim 9, wherein the FRP plate (13) is an automobile part made of FRP, and the secured member (15) is an automobile frame made of metal.
EP14889773.9A 2014-04-18 2014-04-18 Frp plate fastening structure Withdrawn EP3115124A1 (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/JP2014/061070 WO2015159432A1 (en) 2014-04-18 2014-04-18 Frp plate fastening structure

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EP3115124A1 true EP3115124A1 (en) 2017-01-11

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EP14889773.9A Withdrawn EP3115124A1 (en) 2014-04-18 2014-04-18 Frp plate fastening structure

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Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3771480A (en) * 1971-10-27 1973-11-13 Johnson Die & Eng Co Method and apparatus for extruding a rivet form in a layer of metallic material
US4232496A (en) * 1979-04-30 1980-11-11 Tridair Industries Grommet assembly for composite panels
US4428214A (en) * 1982-02-08 1984-01-31 Deere & Company Flow drilling process and tool therefor
DE102009013265B4 (en) * 2009-03-11 2013-01-31 Technische Universität Chemnitz Method and tools for making a mixing assembly
JP5781031B2 (en) * 2012-07-25 2015-09-16 本田技研工業株式会社 Auto body front structure

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO2015159432A1 *

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