EP0917512A2 - Method for producing a steering-wheel cover - Google Patents

Method for producing a steering-wheel cover

Info

Publication number
EP0917512A2
EP0917512A2 EP98928310A EP98928310A EP0917512A2 EP 0917512 A2 EP0917512 A2 EP 0917512A2 EP 98928310 A EP98928310 A EP 98928310A EP 98928310 A EP98928310 A EP 98928310A EP 0917512 A2 EP0917512 A2 EP 0917512A2
Authority
EP
European Patent Office
Prior art keywords
core
steering wheel
plastic
steering
molded part
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Withdrawn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
EP98928310A
Other languages
German (de)
French (fr)
Inventor
Martin Kreuzer
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.)
ZF Automotive Safety Systems Germany GmbH
Original Assignee
TRW Automotive Safety Systems GmbH
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 TRW Automotive Safety Systems GmbH filed Critical TRW Automotive Safety Systems GmbH
Publication of EP0917512A2 publication Critical patent/EP0917512A2/en
Withdrawn legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60R—VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR
    • B60R21/00—Arrangements or fittings on vehicles for protecting or preventing injuries to occupants or pedestrians in case of accidents or other traffic risks
    • B60R21/02—Occupant safety arrangements or fittings, e.g. crash pads
    • B60R21/16—Inflatable occupant restraints or confinements designed to inflate upon impact or impending impact, e.g. air bags
    • B60R21/20—Arrangements for storing inflatable members in their non-use or deflated condition; Arrangement or mounting of air bag modules or components
    • B60R21/203—Arrangements for storing inflatable members in their non-use or deflated condition; Arrangement or mounting of air bag modules or components in steering wheels or steering columns
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60R—VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR
    • B60R21/00—Arrangements or fittings on vehicles for protecting or preventing injuries to occupants or pedestrians in case of accidents or other traffic risks
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C33/00—Moulds or cores; Details thereof or accessories therefor
    • B29C33/44—Moulds or cores; Details thereof or accessories therefor with means for, or specially constructed to facilitate, the removal of articles, e.g. of undercut articles
    • B29C33/52—Moulds or cores; Details thereof or accessories therefor with means for, or specially constructed to facilitate, the removal of articles, e.g. of undercut articles soluble or fusible
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C39/00—Shaping by casting, i.e. introducing the moulding material into a mould or between confining surfaces without significant moulding pressure; Apparatus therefor
    • B29C39/02—Shaping by casting, i.e. introducing the moulding material into a mould or between confining surfaces without significant moulding pressure; Apparatus therefor for making articles of definite length, i.e. discrete articles
    • B29C39/10—Shaping by casting, i.e. introducing the moulding material into a mould or between confining surfaces without significant moulding pressure; Apparatus therefor for making articles of definite length, i.e. discrete articles incorporating preformed parts or layers, e.g. casting around inserts or for coating articles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C44/00—Shaping by internal pressure generated in the material, e.g. swelling or foaming ; Producing porous or cellular expanded plastics articles
    • B29C44/34—Auxiliary operations
    • B29C44/58—Moulds
    • B29C44/583—Moulds for making articles with cavities
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
    • B29C45/14—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor incorporating preformed parts or layers, e.g. injection moulding around inserts or for coating articles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
    • B29C45/17—Component parts, details or accessories; Auxiliary operations
    • B29C45/40—Removing or ejecting moulded articles
    • B29C45/44—Removing or ejecting moulded articles for undercut articles
    • B29C45/4457—Removing or ejecting moulded articles for undercut articles using fusible, soluble or destructible cores
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D1/00—Steering controls, i.e. means for initiating a change of direction of the vehicle
    • B62D1/02—Steering controls, i.e. means for initiating a change of direction of the vehicle vehicle-mounted
    • B62D1/04—Hand wheels
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
    • B29L2031/00—Other particular articles
    • B29L2031/30—Vehicles, e.g. ships or aircraft, or body parts thereof
    • B29L2031/3005—Body finishings
    • B29L2031/3038—Air bag covers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
    • B29L2031/00—Other particular articles
    • B29L2031/30—Vehicles, e.g. ships or aircraft, or body parts thereof
    • B29L2031/3047—Steering wheels
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S264/00—Plastic and nonmetallic article shaping or treating: processes
    • Y10S264/44—Plastic and nonmetallic article shaping or treating: processes using destructible molds or cores in molding processes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00—Metal working
    • Y10T29/49—Method of mechanical manufacture
    • Y10T29/49481—Wheel making
    • Y10T29/49488—Steering wheel
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T74/00—Machine element or mechanism
    • Y10T74/20—Control lever and linkage systems
    • Y10T74/20576—Elements
    • Y10T74/20732—Handles
    • Y10T74/20834—Hand wheels

Definitions

  • the invention relates to a method for producing a steering wheel with a seamless, the steering wheel rim, the steering wheel spokes and the central area for an airbag cover with tear lines encompassing a molded part made in a casting or injection molding process with a closed surface and optionally a foamed base body.
  • the attachment between the base part and the steering wheel rim is associated with additional material expenditure, which runs counter to the general effort to save weight in vehicle construction.
  • the folded gas bag is equipped as a molded part with considerable tolerances, so that the assignment of the cover area is not easy, which - since it must be able to be torn open - must not have any particular inherent rigidity and therefore requires the folded gas bag as an abutment. If the gas bag package is too “thin”, the cover is not adequately supported, if it is "thick”, it bulges upwards. Both are undesirable.
  • the molded plastic part can be manufactured with a precisely fitting hollow shape, into which the airbag module can subsequently be inserted.
  • the airbag module itself cannot be considered as a molded part because of the "soft" surface of the gas bag package, since the predetermined breaking line required in the covering area of the plastic molded part cannot be reproducibly formed.
  • the core made of low-melting material can be used in conjunction with the outer shape
  • a very precisely dimensioned line of small wall thickness can be created in the plastic molded part, which has a tightly tolerated strength and tears open reliably and immediately when the gas bag is inflated
  • sufficiently strong and easily tearable predetermined tear lines can be realized, as well as reinforcement inserts and components acting as a hinge.
  • the one-piece production naturally ensures that the steering wheel and cover area are visually and haptically have the same appearance.
  • a tin-bismuth alloy that melts at about 114 ° C. is suitable as a material that can be melted out of the core.
  • suitable melting waxes or liquids can also be used, since the mold cores need only have a short service life, since the molding times for the plastic molded parts are very short, that is to say in the range from 120 to 240 seconds. A previous cooling of the mold cores can also significantly increase their service life. Further advantages of the method according to the invention result from the fact that the easily melting material used for the cores can be almost completely recovered during melting and can be used again for the production of cores.
  • Fig. 1 shows a section through a steering wheel with melting core
  • Fig. 2 shows a section through a steering wheel according to FIG. 1 with built-in airbag module
  • FIG. 3 shows a section through a steering wheel perpendicular to the section according to FIG. 1.
  • FIG. 1 shows a section through a simplified steering wheel 1, which comprises a steering wheel skeleton with spokes 2 and a hub part 2a and a molded plastic part 3 and whose central installation space is occupied by a meltable core 5.
  • the core 5 is aligned by means of core pins 7 and screws 6 to the hub part 2a and then placed with the skeleton in a casting or injection mold, not shown, in which the plastic molding 3 is molded.
  • the core 5 has a core grade 8 for forming the predetermined breaking point in the cover cap 4, into which a reinforcing insert 4a can be molded in a manner known per se.
  • FIG. 2 an airbag module 12 is inserted in the cavity 11, which is formed after the core 5 has melted (see FIG. 1), and is fastened to the hub part 2a by means of the screws 9.
  • a rear steering wheel cover 10 is shown in section, which is also fastened to the hub part 2a by means of the screws 6. Otherwise, FIG. 2 corresponds to FIG. 1; further explanations and reference numbers are therefore not necessary.
  • Fig. 3 shows a section through the steering wheel perpendicular to the steering wheel axis, but offset by 90 ° with respect to the sections according to FIGS. 1 and 2. This shows the opening 13, which is provided between the molded plastic body 3 and the steering wheel skeleton 2, 2a, in order to be able to install the airbag module 12 in the cavity 11.

Abstract

The invention relates to a method for producing a steering-wheel (1) with a seamless cover encompassing the steering-wheel rim, steering-wheel spokes (2) and the central area with tear lines for an airbag-covering (4). Said cover comprises a plastic shaped part (3) produced as a single piece by a casting or injection process, with a closed surface and optionally a foamed base element. The inventive method is characterised in that a core (5) consisting of a material with a low melting point is attached to the central base part of the steering-wheel skeleton. The steering-wheel skeleton and the core (5) are then placed in a mould to produce the plastic shaped part (3). The plastic shaped part (3) is formed. After said plastic shaped part (3) has hardened, the core (5) is melted by increasing the temperature and the material is removed from the plastic shaped part (3) in liquid form.

Description

Herstellung einer LenkradummantelungManufacture of a steering wheel cover
Beschreibungdescription
Die Erfindung betrifft ein Verfahren zur Herstellung eines Lenkrades mit einer nahtlosen, den Lenkradkranz, die Lenkradspeichen und den zentralen Bereich für eine Airbag- Abdeckung mit Aufreißlinien umfassenden Ummantelung aus einem im Gieß- oder Spritzverfahren einstückig hergestellten Kunststoffformteil mit geschlossener Oberfläche und ggf. geschäumtem Basiskörper.The invention relates to a method for producing a steering wheel with a seamless, the steering wheel rim, the steering wheel spokes and the central area for an airbag cover with tear lines encompassing a molded part made in a casting or injection molding process with a closed surface and optionally a foamed base body.
Die Mehrzahl der Ummantelungen von Lenkrädern mit integriertem Airbag wird heute zweiteilig ausgeführt, mit einem das Lenkradskelett umschließenden Formteil und einer getrennt hergestellten Abdeckung für die Airbag-Einbauöff ung im Nabenbereich des Lenkrades, wobei große Anstrengungen unternommen werden, um beide Teile in ihrem optischen und haptischen Erscheinungsbild aufeinander abzustimmen. Erhebliche weitere Schwierigkeiten ergeben sich aus der Tatsache, daß die Airbag-Abdeckung aufreißbar und um den zur Betätigung der Hupe erforderlichen Tastweg relativ zur Lenkradnabe beweglich ausgebildet sein muß.The majority of the coverings of steering wheels with an integrated airbag are now made in two parts, with a molded part enclosing the steering wheel skeleton and a separately produced cover for the airbag installation opening in the hub area of the steering wheel, with great efforts being made to get both parts in their visual and tactile properties Coordinating appearance. Considerable further difficulties arise from the fact that the airbag cover must be able to be torn open and must be movable relative to the steering wheel hub by the tactile path required to actuate the horn.
Da ein Spalt zwischen dem das Lenkrad umschließenden Formteil und der Airbag- Abdeckung als optisch nachteilig angesehen wird, hat man bereits vorgeschlagen, Formteil und Airbag-Abdeckung einteilig herzustellen. Derartige Verfahren bereiten wegen der zu berücksichtigenden Aufreiß- und Betätigungsfunktionen im Bereich der Airbag-Abdeckungen gewisse, im wesentlichen lösbare fertigungstechnische Schwierig- keiten und erfordern zwingend eine weitgehend neue Auslegung der Lenkradkonstruktion, weil die Montage nur von der Lenkradrückseite her erfolgen kann und weil für das Einbringen des Airbag-Moduls mit zusammengefaltetem Gassack und Gasgenerator be- sondere Vorkehrungen getroffen werden müssen. Vielfach hat man sich damit geholfen, das Lenkradskelett zu unterteilen in ein Basisteil mit Nabe und ggf. Speichenstümpfen, das mit dem Airbag-Modul und anderen Funktionsteilen ausgestattet werden kann, bevor der Lenkradkranz mit Speichen bzw. Speichenstümpfen und einstückiger Umkleidung aufgesetzt und mit dem Basisteil verbunden wird.Since a gap between the molded part enclosing the steering wheel and the airbag cover is considered to be optically disadvantageous, it has already been proposed to produce the molded part and airbag cover in one piece. Because of the tear-open and actuation functions to be taken into account in the area of the airbag covers, such methods pose certain, essentially solvable manufacturing difficulties and require a largely new design of the steering wheel construction, because the assembly can only be carried out from the rear of the steering wheel and because of that Insert the airbag module with the folded airbag and gas generator special precautions must be taken. In many cases, it has helped to divide the steering wheel skeleton into a base part with a hub and, if necessary, spoke stubs, which can be equipped with the airbag module and other functional parts, before the steering wheel rim with spokes or spoke stumps and an integral casing and with the base part is connected.
Als besonders nachteilig wird dabei angesehen, daß die Befestigung zwischen Basisteil und Lenkradkranz mit einem zusätzlichen Materialaufwand verbunden ist, der dem allgemeinen Bestreben nach Gewichtsersparnis im Fahrzeugbau zuwiderläuft. Außerdem ist es schwierig, die beiden Bauteile maßlich optimal aufeinander abzustimmen. Insbesondere der zusammengefaltete Gassack ist als Formteil mit erheblichen Toleranzen ausgestattet, so daß die Zuordnung des Abdeckbereiches nicht einfach ist, der - da er aufreißbar sein muß - keine besondere Eigensteifigkeit aufweisen darf und deshalb den zusammengefalteten Gassack als Widerlager benötigt. Ist das Gassackpaket zu „dünn", wird die Abdeckung nicht ausreichend abgestützt, ist es zu „dick", wird sie nach oben ausgebeult. Beides ist unerwünscht.It is considered to be particularly disadvantageous that the attachment between the base part and the steering wheel rim is associated with additional material expenditure, which runs counter to the general effort to save weight in vehicle construction. In addition, it is difficult to optimally coordinate the two components with one another. In particular, the folded gas bag is equipped as a molded part with considerable tolerances, so that the assignment of the cover area is not easy, which - since it must be able to be torn open - must not have any particular inherent rigidity and therefore requires the folded gas bag as an abutment. If the gas bag package is too "thin", the cover is not adequately supported, if it is "thick", it bulges upwards. Both are undesirable.
Ähnliche Probleme ergeben sich hinsichtlich der Betätigungsbewegungen, die von außen über das einstückig am Lenkradkranz ausgebildete Kunststoffformteil auf die im Basi- steil montierten Betätigungsorgane übertragen werden müssen. Es dürfte ohne weiteres klar sein, daß die Anpassung einer gießformtechnisch hergestellten Oberfläche an eine montierte Oberfläche fertigungstechnisch sehr aufwendig ist und daß die Übertragungsfunktionen nur dann betriebssicher ausgeführt werden können, wenn bei der Anpassung sehr enge Toleranzen eingehalten werden können.Similar problems arise with regard to the actuating movements which have to be transmitted from the outside to the actuating members mounted in the base part via the plastic molded part which is formed in one piece on the steering wheel rim. It should be clear without further ado that the adaptation of a surface produced using casting mold technology to a mounted surface is technically very complex and that the transfer functions can only be carried out in a reliable manner if very tight tolerances can be maintained during the adaptation.
Daraus ergibt sich die Aufgabe, das eingangs genannte Verfahren so weiterzubilden, daß alle vorgenannten Schwierigkeiten überwunden werden können und daß zur Ummantelung eines Lenkrades ein eintsückiges Kunststoffteil mit geschlossener Oberfläche und ggf. geschäumtem Kern geschaffen werden kann, bei dem insbesondere die Anpassungs- probleme mit vertretbarem wirtschaftlichen Aufwand gelöst werden können. Zur Lösung dieser Aufgabe wird erfindungsgemäß vorgeschlagen daß am zentralen Basisteil des Lenkradskeletts ein Kern aus einem niedrig schmelzenden Material befestigt wird, das danach Lenkradskelett und Kern in eine Form zur Ausbildung des Kunststoffformteils eingelegt werden, daß der Kunststoffformteil hergestellt und daß nach der Ver- festigung des Kunststoffformteils der Kern durch Temperaturerhöhung aufgeschmolzen und das Material in flüssiger Form aus dem Kunststoffformteil entfernt wird.This results in the task of further developing the aforementioned method so that all of the aforementioned difficulties can be overcome and that a one-piece plastic part with a closed surface and possibly a foamed core can be created for the sheathing of a steering wheel, in which in particular the adaptation problems with reasonable economic effort can be solved. To achieve this object, it is proposed according to the invention that a core made of a low-melting material is attached to the central base part of the steering wheel skeleton, which then the steering wheel skeleton and core are inserted into a mold for forming the plastic molded part, that the plastic molded part is produced and that after the solidification of the Melted plastic part of the core by increasing the temperature and the material is removed in liquid form from the plastic molded part.
Durch die Verwendung eines Kerns aus niedrig schmelzendem Material kann das Kunststoffformteil mit einer paßgenauen Hohlform hergestellt werden, in die nachträg- lieh das Airbag-Modul eingebracht werden kann. Das Airbag-Modul selbst kommt wegen der „weichen" Oberfläche des Gassackpakets als Formteil nicht in Betracht, da damit die im Abdeckbereich des Kunststoffformteils erforderliche Sollbruchlinie nicht reproduzierbar ausgeformt werden kann. Mit dem Kern aus niedrig schmelzenden Material hingegen, kann in Verbindung mit der Außenform im Kunststoffformteil eine sehr genau dimensionierte Linie geringer Wanddicke erzeugt werden, die eine eng tolerierte Festigkeit aufweist und beim Aufblasen des Gassacks zuverlässig und unverzüglich aufreißt. Die Herstellung des Abdeckbereichs ist damit genauso einfach, wie bei einer als gesondertes Bauteil hergestellten Abdeckkappe, d.h. es können im Normalbetrieb ausreichend belastbare und im Notfall leicht aufreißbare Sollrißlinien ebenso realisiert werden, wie Verstärkungseinlagen und als Scharnier wirkende Bauteile. Außerdem ist durch die einstückige Herstellung selbstverständlich gewährleistet, daß Lenkrad- und Abdeckbereich optisch und haptisch das gleiche Erscheinungsbild aufweisen.By using a core made of low-melting material, the molded plastic part can be manufactured with a precisely fitting hollow shape, into which the airbag module can subsequently be inserted. The airbag module itself cannot be considered as a molded part because of the "soft" surface of the gas bag package, since the predetermined breaking line required in the covering area of the plastic molded part cannot be reproducibly formed. In contrast, the core made of low-melting material can be used in conjunction with the outer shape A very precisely dimensioned line of small wall thickness can be created in the plastic molded part, which has a tightly tolerated strength and tears open reliably and immediately when the gas bag is inflated In normal operation, sufficiently strong and easily tearable predetermined tear lines can be realized, as well as reinforcement inserts and components acting as a hinge. In addition, the one-piece production naturally ensures that the steering wheel and cover area are visually and haptically have the same appearance.
Als ausschmelzbares Material für den Kern kommt insbesondere eine bei etwa 114°C schmelzende Zinn-Wismut-Legierung in Betracht. Es können aber auch geeignete Schmelzwachse oder Flüssigkeiten verwendet werden, denn die Formkerne müssen nur geringe Standzeiten aufweisen, da die Ausformzeiten für die Kunststoffformteile sehr gering sind, d.h. im Bereich von 120 bis 240 Sekunden liegen. Durch eine vorausgehende Kühlung der Formkerne kann im übrigen deren Standzeit wesentlich erhöht werden. Weitere Vorteile des erfindungsgemäßen Verfahrens ergeben sich daraus, daß das für die Kerne verwendete, leicht schmelzende Material beim Ausschmelzen nahezu vollständig zurückgewonnen und erneut für die Herstellung von Kernen verwendet werden kann.In particular, a tin-bismuth alloy that melts at about 114 ° C. is suitable as a material that can be melted out of the core. However, suitable melting waxes or liquids can also be used, since the mold cores need only have a short service life, since the molding times for the plastic molded parts are very short, that is to say in the range from 120 to 240 seconds. A previous cooling of the mold cores can also significantly increase their service life. Further advantages of the method according to the invention result from the fact that the easily melting material used for the cores can be almost completely recovered during melting and can be used again for the production of cores.
Weitere vorteilhafte Ausgestaltungen des erfindungsgemäßen Verfahrens sind in den Unteransprüchen 5 bis 9 beschrieben. Damit läßt sich das Verfahren an die verschiedensten Anwendungszwecke und Anforderungen anpassen. Mit der Erfindung wird demnach ein Verfahren vorgeschlagen, mit dem nicht nur die eingangs genannten Schwierigkeiten überwunden werden können, das vielmehr auch noch äußerst flexibel und be- triebssicher ist.Further advantageous refinements of the method according to the invention are described in subclaims 5 to 9. The method can thus be adapted to a wide variety of applications and requirements. The invention accordingly proposes a method which can not only be used to overcome the difficulties mentioned at the outset, but which is also extremely flexible and reliable.
Das erfindungsgemäße Verfahren wird anhand des in den Figuren 1 bis drei vereinfacht dargestellten Ausfuhrungsbeispiels näher erläutert. Es zeigenThe method according to the invention is explained in more detail with reference to the exemplary embodiment shown in simplified form in FIGS. 1 to three. Show it
Fig. 1 einen Schnitt durch ein Lenkrad mit Schmelzkern undFig. 1 shows a section through a steering wheel with melting core and
Fig. 2 einen Schnitt durch ein Lenkrad gemäß Fig. 1 mit eingebautem Airbag- Modul undFig. 2 shows a section through a steering wheel according to FIG. 1 with built-in airbag module and
Fig. 3 einen Schnitt durch ein Lenkrad senkrecht zum Schnitt gemäß Fig. 1.3 shows a section through a steering wheel perpendicular to the section according to FIG. 1.
In Figur 1 ist ein Schnitt durch ein vereinfachtes Lenkrad 1 dargestellt, das ein Lenkradskelett mit Speichen 2 und einem Nabenteil 2a sowie ein Kunststoffformteil 3 umfaßt und dessen zentraler Einbauraum von einem ausschmelzbaren Kern 5 eingenommen ist. Der Kern 5 wird mittels Kernstiften 7 und Schrauben 6 zum Nabenteil 2a ausgerichtet und dann mit dem Skelett in eine nicht dargestellte Gieß- oder Spritzform eingelegt, in der das Kunststoffformteil 3 ausgeformt wird. Das Kunststoffformteil 3 umschließt, wie üblich, den Lenkradkranz und die Speichen 2. Es besitzt eine einstückig angeformte Abdeckkappe 4 für das Airbag-Modul 12 (siehe Fig. 2). das nach dem Ausschmelzen des Kerns 5 in den entstehenden Hohlraum eingebaut wird. Der Kern 5 besitzt einen Kerngrad 8 zur Ausbildung der Sollbruchstelle in der Abdeckkappe 4, in die in an sich bekannter Weise eine Verstärkungseinlage 4a eingeformt sein kann.FIG. 1 shows a section through a simplified steering wheel 1, which comprises a steering wheel skeleton with spokes 2 and a hub part 2a and a molded plastic part 3 and whose central installation space is occupied by a meltable core 5. The core 5 is aligned by means of core pins 7 and screws 6 to the hub part 2a and then placed with the skeleton in a casting or injection mold, not shown, in which the plastic molding 3 is molded. The plastic molded part 3, as usual, encloses the steering wheel rim and the spokes 2. It has an integrally molded cover cap 4 for the airbag module 12 (see FIG. 2). which is installed in the resulting cavity after the core 5 has melted out. The core 5 has a core grade 8 for forming the predetermined breaking point in the cover cap 4, into which a reinforcing insert 4a can be molded in a manner known per se.
In Fig. 2 ist in dem Hohlraum 11, der nach dem Ausschmelzen des Kerns 5 (siehe Fig. 1) entsteht, ein Airbag-Modul 12 eingesetzt und mittels der Schrauben 9 am Nabenteil 2a befestigt. Außerdem ist eine rückseitige Lenkradverkleidung 10 im Schnitt dargestellt, die mittels der Schrauben 6 ebenfalls am Nabenteil 2a befestigt ist. Im übrigen entspricht Fig. 2 der Fig. 1 ; weitere Erläuterungen und Bezugsziffern sind daher nicht erforderlich.In FIG. 2, an airbag module 12 is inserted in the cavity 11, which is formed after the core 5 has melted (see FIG. 1), and is fastened to the hub part 2a by means of the screws 9. In addition, a rear steering wheel cover 10 is shown in section, which is also fastened to the hub part 2a by means of the screws 6. Otherwise, FIG. 2 corresponds to FIG. 1; further explanations and reference numbers are therefore not necessary.
Fig. 3 zeigt einen Schnitt durch das Lenkrad senkrecht zur Lenkradachse, aber um 90° gegenüber den Schnitten gemäß Fig. 1 und 2 versetzt. Damit wird die Öffnung 13 ersichtlich, die zwischen Kunststoffformkörper 3 und Lenkradskelett 2, 2a vorgesehen ist, um das Airbag-Modul 12 in den Hohlraum 11 einbauen zu können. Fig. 3 shows a section through the steering wheel perpendicular to the steering wheel axis, but offset by 90 ° with respect to the sections according to FIGS. 1 and 2. This shows the opening 13, which is provided between the molded plastic body 3 and the steering wheel skeleton 2, 2a, in order to be able to install the airbag module 12 in the cavity 11.

Claims

Patentansprüche claims
1. Verfahren zur Herstellung eines Lenkrades mit einer nahtlosen, den Lenkradkranz, die Lenkradspeichen und den zentralen Bereich für eine Airbag- Abdeckung mit Aufreißlinien umfassenden Ummantelung aus einem im Gießoder Spritzverfahren einstückig hergestellten Kunststoffformteil mit geschlossener Oberfläche und ggf. geschäumtem Basiskörper, dadurch gekennzeichnet, daß am zentralen Basisteil des Lenkradskeletts ein Kern aus einem niedrig schmelzenden Material befestigt wird, das danach Lenkradskelett und Kern in eine Form zur Ausbildung des Kunststoffformteils eingelegt werden, daß der Kunststoffformteil hergestellt und daß nach der Verfestigung des Kunststoffformteils der Kern durch Temperaturerhöhung aufgeschmolzen und das Material in flüssiger Form aus dem Kunststoffformteil entfernt wird.1. A method for producing a steering wheel with a seamless, the steering wheel rim, the steering wheel spokes and the central area for an airbag cover with tear lines encompassing a molded part made in one piece by casting or injection molding with a closed surface and possibly foamed base body, characterized in that a core made of a low-melting material is attached to the central base part of the steering wheel skeleton, the steering wheel skeleton and core are then inserted into a mold for forming the plastic molded part, that the plastic molded part is produced and that after the plastic molded part has solidified, the core is melted by increasing the temperature and the material is in liquid form is removed from the molded plastic part.
2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß als Kern eine bei etwa 114 °C schmelzende Zinn- Wismut Metallegierung verwendet wird.2. The method according to claim 1, characterized in that a tin-bismuth metal alloy melting at about 114 ° C is used as the core.
3. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß als Kern ein bei 60 bis 115°C schmelzendes Wachs verwendet wird.3. The method according to claim 1, characterized in that a melting at 60 to 115 ° C wax is used as the core.
4. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß als Kern eine erstarrte bei -10 bis + 10°C schmelzende Flüssigkeit verwendet wird. 4. The method according to claim 1, characterized in that a solidified at -10 to + 10 ° C melting liquid is used as the core.
5. Verfahren nach einem der Ansprüche 1 bis 4, dadurch gekennzeichnet, daß die Ummantelung aus einem geeigneten Kunststoff nach dem .sogenannten Integralschaumverfahren hergestellt wird.5. The method according to any one of claims 1 to 4, characterized in that the casing is made of a suitable plastic by the so-called integral foam process.
6. Verfahren nach Anspruch 5, dadurch gekennzeichnet, daß schäumbares Polyure- tan verwendet wird.6. The method according to claim 5, characterized in that foamable polyurethane is used.
7. Verfahren nach einem der Ansprüche 1 bis 4, dadurch gekennzeichnet, daß die Ummantelung aus zwei verschiedenen Kunststoffen nach dem sogenannten 2K- Verfahren hergestellt wird.7. The method according to any one of claims 1 to 4, characterized in that the casing is made of two different plastics by the so-called 2K process.
8. Verfahren nach Anspruch 7, dadurch gekennzeichnet, daß thermoplastische Kunststoffe verwendet werden.8. The method according to claim 7, characterized in that thermoplastic materials are used.
9. Verfahren nach einem der Ansprüche 1 bis 8, dadurch gekennzeichnet, daß die Ummantelung im Bereich der Airbag-Abdeckkappe eine Verstärkungseinlage aus einem Kunststoffgewebe, einem Kunststoffnetz, einer perforierten Metall- oder Kunststoffolie oder dergl. aufweist, die längs der Schwächungslinie weggelassen bzw. unterbrochen ist. 9. The method according to any one of claims 1 to 8, characterized in that the sheathing in the area of the airbag cover cap has a reinforcing insert made of a plastic fabric, a plastic mesh, a perforated metal or plastic film or the like, which is omitted along the line of weakness or is interrupted.
EP98928310A 1997-05-24 1998-05-22 Method for producing a steering-wheel cover Withdrawn EP0917512A2 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE19721789 1997-05-24
DE19721789A DE19721789A1 (en) 1997-05-24 1997-05-24 Manufacture of a steering wheel cover
PCT/EP1998/003028 WO1998052796A2 (en) 1997-05-24 1998-05-22 Method for producing a steering-wheel cover

Publications (1)

Publication Number Publication Date
EP0917512A2 true EP0917512A2 (en) 1999-05-26

Family

ID=7830404

Family Applications (1)

Application Number Title Priority Date Filing Date
EP98928310A Withdrawn EP0917512A2 (en) 1997-05-24 1998-05-22 Method for producing a steering-wheel cover

Country Status (8)

Country Link
US (1) US6098286A (en)
EP (1) EP0917512A2 (en)
JP (1) JP2001501889A (en)
KR (1) KR20000029480A (en)
BR (1) BR9804925A (en)
CA (1) CA2261965A1 (en)
DE (1) DE19721789A1 (en)
WO (1) WO1998052796A2 (en)

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE29901404U1 (en) * 1999-01-27 1999-04-29 Trw Automotive Safety Sys Gmbh Motor vehicle steering wheel
DE19904746A1 (en) * 1999-02-05 2000-08-10 Trw Automotive Safety Sys Gmbh Manufacturing process for a steering wheel casing
DE19956170A1 (en) * 1999-11-23 2001-05-31 Mann & Hummel Filter Lost metal core method for producing an internal combustion engine suction tube uses a meltable core held by an insert which eventually forms part of the molding
DE10020677A1 (en) * 2000-04-27 2001-10-31 Delphi Tech Inc Folding method and device
DE10123520C1 (en) * 2001-05-15 2002-10-10 Trw Automotive Safety Sys Gmbh Production of a steering wheel comprises manufacturing a steering wheel frame having a closed annular section with an open hollow profile, inserting a body into the open hollow profile, and coating the frame with foam and/or leather
CN114435457A (en) * 2020-10-30 2022-05-06 奥托立夫开发公司 Steering wheel leather wrapping method and steering wheel
CN115431007A (en) * 2022-10-17 2022-12-06 宝武集团马钢轨交材料科技有限公司 Method for manufacturing elastic wheel

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1601817A (en) * 1977-05-31 1981-11-04 Ford Motor Co Plastics moulding process
GB2287305B (en) * 1994-03-03 1998-05-13 Autoliv Dev Improvements in or relating to a steering wheel arrangement
EP0732237A1 (en) * 1995-03-16 1996-09-18 General Motors Corporation Steering wheel assembly

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9852796A2 *

Also Published As

Publication number Publication date
BR9804925A (en) 1999-09-08
CA2261965A1 (en) 1998-11-26
DE19721789A1 (en) 1998-11-26
WO1998052796A2 (en) 1998-11-26
WO1998052796A3 (en) 1999-05-27
US6098286A (en) 2000-08-08
JP2001501889A (en) 2001-02-13
KR20000029480A (en) 2000-05-25

Similar Documents

Publication Publication Date Title
DE10207705B4 (en) Molded, seamless vehicle interior trim for concealing an airbag
DE19819573B4 (en) dashboard
EP1187734B1 (en) Vehicle door with door casing and method for the production thereof
EP1731381B1 (en) Base module for an airbag device, associated airbag device, manufacturing method and manufacturing tool for an airbag module
EP1084052B1 (en) Vehicle part with an airbag device and method for producing a vehicle part of this type
EP0741062A2 (en) Airbag cover and method for its production
DE19651532A1 (en) Airbag cover for motor vehicle
EP1602549B1 (en) Vehicle steering wheel
DE202006009442U1 (en) Cover unit for airbag, comprising decorative border and other areas created during production process
EP2006165B1 (en) Interior lining with integrated airbag cover for a motor vehicle and method for its manufacture
DE102005050370B4 (en) A method of making a motor vehicle trim assembly comprising a unified airbag door
EP0646499B1 (en) Dash-board in a motor car
DE69818682T2 (en) AIR CUSHION PANEL AND METHOD FOR THE PRODUCTION THEREOF
EP1393994A1 (en) Air bag cover comprising a reinforcement of lightweight plastic
CN102470734A (en) Reinforced door frame construction for vehicle
WO2001042060A1 (en) Airbag system for motor vehicles integrated in an inner trim piece
EP0917512A2 (en) Method for producing a steering-wheel cover
EP2059417B1 (en) Airbag covering
DE19904746A1 (en) Manufacturing process for a steering wheel casing
DE4424686B4 (en) Airbag cover
DE102020127074A1 (en) AIRBAG CHAMBER ARRANGEMENT
DE10223302A1 (en) Airbag cover for a lining used in the interior of a vehicle, comprises reinforcement elements joined to an embedding carrier layer produced by injection molding
EP2015912B1 (en) Method for producing a moulded part with an opening groove
DE102007023075A1 (en) Process to manufacture an automotive airbag module with components of same type of plastic and different thickness
EP1952964B1 (en) Method for producing a dashboard

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

17P Request for examination filed

Effective date: 19981229

AK Designated contracting states

Kind code of ref document: A2

Designated state(s): DE ES FR GB IT

RAP1 Party data changed (applicant data changed or rights of an application transferred)

Owner name: TRW AUTOMOTIVE SAFETY SYSTEMS GMBH & CO. KG

GRAG Despatch of communication of intention to grant

Free format text: ORIGINAL CODE: EPIDOS AGRA

GRAG Despatch of communication of intention to grant

Free format text: ORIGINAL CODE: EPIDOS AGRA

GRAH Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOS IGRA

17Q First examination report despatched

Effective date: 20001013

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN

18D Application deemed to be withdrawn

Effective date: 20010616