Abstract:
To provide a seat belt component having a molded resin surface in which the burr formed by the resin is less conspicuous or eliminated. The seat belt component could be a shoulder anchor and have the added benefit of allowing the seat belt to slide smoothly therethrough. An externally formed structural element is formed on the metal surface to prevent further flow of the synthetic resin.

Description:
This application is related to Japanese Patent Application No. H11-237277, filed Aug. 24, 1999, the disclosure of which is hereby incorporated by reference in its entirety. 
     FIELD OF INVENTION 
     The present invention generally relates to components onto which a resin is molded, and more specifically, molding a resin body onto seat belt components such as a shoulder anchor, a tongue, and the like to lessen or eliminate burrs. 
     BACKGROUND OF THE INVENTION 
     The outer surfaces of seat belt components that are touched by a person&#39;s hand are typically molded out of a synthetic resin. At least a portion of the metal components may be covered by the resin. 
     FIGS.  6 ( a ) and ( b ) are schematic sectional views illustrating the molding of a synthetic resin onto the outer surfaces of a metal plate by a conventional mold processing method. As shown in FIG.  6 ( a ), a metal plate  3  is inserted into a cavity  4 . Cavity  4  is created by the joining of metal molds  1  and  2 . A synthetic resin is charged into the cavity  4  by an injection machine or the like. After the resin hardens and the metal molds are removed, a component composed of the metal plate  3  whose outer surfaces are covered with a synthetic resin molded body  5  is obtained, as shown in FIG.  6 ( b ). 
     According to the above-mentioned conventional mold processing method, a relatively large burr  6  can be made because the synthetic resin flows along the outer surfaces of the plate  3 . The burr is created along at least a partial length of the defining edge or outer boundary of the molded resin body. The burr  6  not only lessens the aesthetics of the component but also possibility generates a friction force when coming into contact with a seat belt and thereby at least partially obstructing the smooth motion of the seat belt. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to overcome the drawback caused by a burr formed by the molding process. The burr is lessened in size or eliminated by forming an externally standing step surface or surfaces on the metal portion, preferably near the end of the molded resin body. 
     In such a molded component, the stepped surfaces would prevent the flow of synthetic resin. However, the occurrence of a large burr and/or the occurrence of a burr that obstructs the smooth sliding of a seat belt can be prevented. Specifically, when the metal component is inserted into the metal molds and a resin is injected, the injection is carried out by abutting the stepped surfaces of the metal component against the inner surfaces of the metal molds, and the stepped surfaces are pressed against the metal molds by the pressure of the injected resin. Accordingly, no or a smaller gap is formed between the stepped surfaces and the inner surfaces of the metal molds and consequently no or a smaller burr is made. 
     The present invention is directed to overcoming or at least reducing some of the problems set forth above and at least is directed to accomplishing at least some of the objectives set forth above. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a plan view of an shoulder anchor according to an embodiment of the invention. 
     FIG. 2 is a transverse sectional view taken along the line II—II of FIG.  1 . 
     FIG. 3 is partial enlarged view of the rear portion of the shoulder anchor shown by III of FIG.  1 . 
     FIG. 4 is a sectional view taken along the line IV—IV of FIG.  3 . 
     FIG. 5 is a partial enlarged view of the portion V of FIG.  2 . 
     FIG. 6 is a sectional view showing a conventional example. 
     FIG. 7 is a sectional view showing an embodiment of the present invention, with 
     FIG.  7 ( a ) showing the injection molding set-up and FIG.  7 ( b ) showing the finished product. 
     FIG. 8 is a sectional view showing an embodiment of the present invention. 
     FIG. 9 is a sectional view showing an embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     An embodiment of the present invention will be described below with reference to drawings. FIG. 7 is a sectional view showing a component according to an embodiment of the present invention and also illustrates a method of manufacturing the component. 
     As shown in FIG.  7 ( a ), a metal plate  3 A is inserted into a cavity  4 A formed by metal molds  1 A and  1 B and a synthetic resin is charged into the cavity  4 A by an injection machine or the like. A component having a synthetic resin molded body  5 A molded on the outer surfaces thereof is obtained after hardening the resin and removing the molds, as shown in FIG.  7 ( b ). The metal plate  3 A includes externally standing stepped surfaces  7  at portions near, and preferably very near, to an end of the synthetic resin molded body  5 A. The provision of the stepped surfaces  7  prevents the flow of the synthetic resin any further down the length of the metal plate  3 A and no burr spreads in an excessively wide range. Further, even if a burr is made, because it is at least concealed by the stepped surfaces  7 , there is not a possibility that a seat belt is abutted against the burr so that the seat belt smoothly slides on the component at all times. 
     In another embodiment of the present invention, stepped surfaces  8  may be formed by defining grooves or indentations as in a metal plate  3 B of FIG.  8 . Alternatively, in yet another embodiment, stepped surfaces  9  may be formed by providing projections as in a metal plate  3 C of FIG.  9 . 
     FIGS. 1 to  5  show the arrangement of a shoulder anchor according to the first embodiment of the present invention. The shoulder anchor  10  includes a metal plate  11 , a seat belt guide  12  fitted on the plate  11  and having a C-shaped cross section, and synthetic resin molded bodies  13  molded so as to adhere to the plate  11  and the seat belt guide  12 . 
     A bolt insertion hole  14  is defined through the front portion  11 A of the plate  11  to fasten the shoulder anchor  10  to the pillar or the like of an automobile. Further, an opening (slot)  15  is defined at the rear portion  11 B of the plate  11  to pass a seat belt  20  therethrough. A seat belt guide  12  is mounted on the rear edge portion (right edge of FIG. 2) of the inner peripheral edge of the opening  15 . 
     One of the synthetic resin molded bodies  13  is molded on the rear portion of the plate  11  using metal molds. The synthetic resin molded body  13  is formed so as to expose the curved surface of tie seat belt guide  12  on the opening  15  side thereof. Further, the synthetic resin molded body  13  covers the rear end surface (right end surface of FIG. 2) of the seat belt guide  12 . As shown explicitly in FIGS. 3,  4  and  5 , a recessed stepped portion  16  having a stepped surface  17  is formed on the projecting square portion of the seat belt guide  12 . The synthetic resin molded body  13  is formed so as to come into the recessed stepped portion  16 . 
     The seat belt  20  is inserted through the opening  15  of the shoulder anchor  10  arranged as described above and extended along the seat belt guide  12 . In the shoulder anchor  10 , because the stepped surface  17  is defined on the projecting square portion of the seat belt guide  12 , the synthetic resin molded body  13  does not protrude to the outer peripheral surface (surface for guiding the seat belt) of the seat belt guide  12 . As a result, a burr, which at least partially obstructs the smooth sliding of the seat belt  20 , is not made or is made of a smaller size. Accordingly, the seat belt  20  smoothly slides through the seat belt guide  12  at all times. 
     As described above, when a seat belt component of the present invention is made, the burr of the synthetic resin molded body is less conspicuous and has better aesthetics qualities. Further, the seat belt can slide more smoothly at all times through the component because no burr or a smaller burr is created, thereby allowing for decreased obstruction of its travel. 
     While preferred embodiments have been shown and described, it should be understood that the changes and modifications can be made therein without departing significantly from the invention in its broader aspects. For example, while reference number  10  in FIGS. 1-5 refers to a shoulder anchor, the reference number  10  could also refer to a tongue for a seat belt buckle or other similar component. Various features of the invention are recited in the following claims. Furthermore, the figures are provided for the purpose of illustration and are not necessarily drawn to scale.