SCREW FASTENING STRUCTURE WITH HIGH-STRENGTH SELF-FORMING SCREW

• Main Authors: MATSUNO, MAYUMI, MORI, SHIGETO, UMADA, AKIHIDE
• Format: Patent
• Language: English; French; Japanese
• Published: 21.01.2010
• Subjects: BLASTING; DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS ORMACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS,CLIPS, WEDGES, JOINTS OR JOINTING; ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVEFUNCTIONING OF MACHINES OR INSTALLATIONS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; HEATING; LIGHTING; MECHANICAL ENGINEERING; TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION; TECHNICAL SUBJECTS COVERED BY FORMER USPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS; THERMAL INSULATION IN GENERAL; WEAPONS

To provide a screw fastening structure for enhancing the strength of a bolt and fatigue strength by reducing the machining process without altering the shape of an associated member, and for achieving downsizing by keeping the fitting length of a thread almost the same as that of the prior art, thus contributing remarkably to weight reduction of a vehicle. A self-forming screw (1) having a strength 14T produced by form rolling before heat treatment is employed as a fastening bolt, and the self-forming screw is driven into a member (4) having an as-cast, nonthreaded rough hole (5). In a screw fastening structure to which a fixing member (6) is fastened, the catch rate of a female screw and a male screw formed by a self-form is 75-90%, the fitting length of the screw and the rough hole is d-2.5d (d is screw diameter), and no clearance appears at the contact surface of the male and female screws because of self-forming screw fastening. L'invention vise à proposer une structure de fixation de vis pour améliorer la résistance d'un boulon et la résistance à la fatigue par réduction du traitement d'usinage sans modification de la forme d'un élément associé, et pour atteindre une réduction des dimensions par le maintien de la longueur d'adaptation d'un filetage à une valeur presque identique à celle de l'état de la technique, contribuant ainsi de façon remarquable à la réduction du poids d'un véhicule. Une vis auto-foreuse (1) ayant une résistance (14T) produite par laminage de forme avant traitement thermique est employée comme boulon de fixation, et la vis auto-foreuse est enfoncée dans un élément (4) ayant un trou rugueux non fileté tel que coulé (5). Dans une structure de fixation de vis à laquelle est fixé un élément de fixation (6), le taux de contact d'une vis femelle et d'une vis mâle formées par un auto-forage est de 75-90 %, la longueur d'adaptation de la vis et du trou rugueux est de d-2,5d (d est le diamètre de la vis), et aucun espace n'apparaît au niveau de la surface de contact des vis mâle et femelle en raison de la fixation de vis auto-foreuse.