Fastener

Abstract

A fastener, comprising an expander part having a saucer-shaped head and a shank extending from the head and formed with a male thread thereon, and a fastener part having a flange and opposite stem portions branched from the back of the flange and connecting through hinge portions to guide portions which join each other at the other ends thereof, the expander part and fastener part each being made of a resin, the fastener part having a circular bore extending from the flange to the stem portions to permit the expander part to be inserted in and temporarily retained in the stem portions, the circular bore having therein opposite bulges positioned ahead of the hinge portions to spread the stem portions outward away from each other when the expander part is pushed.

We claim: 
     
       1. A fastener comprising: an expander part comprising: a saucer-shaped head; and   a shank extending from said head and formed with a male thread thereon; and     a fastener part comprising: a flange and opposite stem portions .[.diversing.]. .Iadd.diverging .Iaddend.from a position of said fastener part adjacent to a back of said flange and connecting through .[.hing.]. .Iadd.hinge .Iaddend.portions to guide portions which join each other at the other ends thereof;   a circular bore extending from the flange to the stem portions to permit said .[.extending.]. .Iadd.expander .Iaddend.part to be inserted therein;   opposite bulges positioned at the bottom of said bore to spread said stem portions outward away from each other when said .[.expanded.]. .Iadd.expander .Iaddend.part is pushed into said bore and into engagement with said opposite bulges; and     at least one small lug provided on a wall of said bore for engagement with said male thread for temporarily holding said .[.expanded.]. .Iadd.expander .Iaddend.part and said fastener part together until said .[.expanded.]. .Iadd.expander .Iaddend.part is pushed into said bore to spread said stem portions whereby said .[.expanded.]. .Iadd.expander .Iaddend.part and said fastener part are prevented from being separated during handling and transportation.   
     
     
       2. A fastener as claimed in claim 1, wherein said head of said expander part has a thickness thereof which is progressively reduced toward the circumferential edge. 
     
     
       3. A fastener as claimed in claim 1, wherein said flange of said fastener part is larger in diameter than said head of said expander part and has a thickness progressively decreasing toward the circumferential edge. 
     
     
       4. A fastener as claimed in claim 1, wherein said expander part and said fastener part are made of plastic resin. .Iadd. 
     
     
       5.  A fastener as claimed in claim 1, wherein said bulges are located closer than said hinge portions to said flange. .Iaddend. .Iadd.6. A fastener as claimed in claim 1, wherein said lug occupies only a small part of the circumferential extent of said bore. .Iaddend. .Iadd.7. A fastener as claimed in claim 1, wherein the diameter of said bore is substantially equal to the outside diameter of a portion of said shank having said male thread formed thereon. .Iaddend. .Iadd.8. A fastener as claimed in claim 1, wherein said hinge portions are constituted by portions having a reduced cross section relative to said stem portions. .Iaddend. .Iadd.9. A fastener as claimed in claim 1, wherein adjacent edges of said stem portions, said hinge portions, and said guide portions define a slot which extends longitudinally along said stem portions, diverges toward said hinge portions, and converges along said guide portions. .Iaddend. .Iadd.10. A fastener as claimed in claim 1, wherein said lug and said male thread are situated such that when said shank of said expander part is pushed all the way into said fastener part, said head of said expander part is proximate to said flange of said fastener 
     
     
        part and said lug still engages said male thread. .Iaddend. .Iadd.11.  A fastener as claimed in claim 10, wherein said lug is located near an entrance end of said bore, and said male thread extends from a point proximate to said head of said expander part over a major portion of the length of said shank of said expander part. .Iaddend. .Iadd.12. A fastener as claimed in claim 11, wherein said lug occupies only a small part of the circumferential extent of said bore, and said bore has a diameter substantially equal to the outer diameter of a portion of said shank having said male thread formed thereon. .Iaddend. .Iadd.13. A fastener as claimed in claim 12, wherein said bulges are located closer than said hinge portions to said flange, said hinge portions are constituted by portions having a reduced cross section relative to said stem portions, and adjacent edges of said stem portions, said hinge portions, and said guide portions define a slot that extends longitudinally along said stem portions, diverges toward said hinge portions, and converges along said guide portions. .Iaddend. .Iadd.14. A fastener as claimed in claim 13, wherein said expander part and said fastener part are formed of plastic resin. .Iaddend. .Iadd.15. A fastener as claimed in claim 1, wherein said bulges are positioned intermediate a bottom of said bore and said hinge portions, and said hinge portions are constituted by portions having a 
     
     
        reduced cross section relative to said stem portions. .Iaddend. .Iadd.16. A fastener as claimed in claim 15, wherein adjacent edges of said stem portions, said hinge portions, and said guide portions define a slot which extends longiudinally along said stem portions, diverges toward said hinge portions, and converges along said guide portions. .Iaddend. .Iadd.17. A fastener as claimed in claim 15, wherein said lug occupies only a small part of the circumferential extent of said bore, and said bore has a diameter substantially equal to the outer diameter of a portion of said shank having said male thread formed thereon. .Iaddend. .Iadd.18. A fastener as claimed in claim 17, wherein said lug and said male thread are situated such that when said shank of said expander part is pushed all the way into said fastener part, said head of said expander part is proximate to said flange of said fastener part and said lug still engages said male thread. .Iaddend. .Iadd.19. A fastener as claimed in claim 18, wherein said lug is positioned near an entrance end of said bore, and said male thread extends from a point proximate to said head of said expander part over a major portion of the length of said shank. .Iaddend. .Iadd.20. A fastener as claimed in claim 15, wherein said expander part and said 
     
     
        fastener part are made of plastic resin. .Iaddend. .Iadd.21.  A fastener as claimed in claim 1, wherein said lug occupies only a small part of the circumferential extent of said bore, and said bore has a diameter substantially equal to the outer diameter of a portion of said shank having said male thread formed thereon. .Iaddend. .Iadd.22. A fastener as claimed in claim 21, wherein said lug and said male thread are situated such that when said shank of said expander part is pushed all the way into said fastener part, said head of said expander part is proximate to said flange of said fastener part and said lug still engages said male thread. .Iaddend. .Iadd.23. A fastener as claimed in claim 22, wherein said bulges are located closer than said hinge portions to said flange, said hinge portions are constituted by portions having a reduced cross section relative to said stem portions, and adjacent edges of said stem portions, said hinge portions, and said guide portions define a slot that extends longitudinally along said stem portions, diverges towards said hinge portions, and converges along said guide portions. .Iaddend. .Iadd.24. A fastener as claimed in claim 23, wherein said expander part and said fastener part are made of plastic resin. .Iaddend.