The invention relates to a grommet for use on a sheet material comprising: an eyelet of a resilient material and including a cylindrical barrel with one end open and an annular flange extending around the other end of the barrel; and a washer of a resilient material having a central bore of a diameter substantially equal to the outside diameter of the barrel and slidably receivable on the barrel; said open end of said barrel being radially bendable so as to be directed toward said flange in engagement with said washer to effect permanent securing.
An example of a grommet of this type is disclosed in AU-A-428 493. After the piercing of the eyelet's barrel through the sheet material such as textile articles the washer is placed on the barrel whereupon the open end thereof is curled or deformed otherwise, so as to fit securely over the washer. Prior to this coupling or clamping operation the washer is often liable to get loose and fall apart from the eyelet requiring the user to hold these parts together all way until the moment they are clamped into place by a tool.
DE-A-1 610 352 discloses another type of a grommet for use on a sheet material comprising an eyelet of a resilient material and including a cylindrical barrel with one end open and an annular flange extending around the other end of the barrel; a washer of a resilient metal having a central bore of a diameter substantially equal to the outside diameter of the barrel and slidably receivable on the barrel; said eyelet having a projection projecting radially outwardly from the barrel and extending around thereof. In this prior art grommet the projection of the eyelet's barrel serves for connecting the eyelet to the washer permanently. In other words, the washer is just slipped on the barrel of the eyelet until the front side of the washer bears against a piece of fabric, e.g. a piece of garment, and the projection of the barrel engages over the rear side of the washer. For using the grommet on fabrics of different thickness the periphery of the barrel must be formed with a plurality of radially extending projections disposed at different spacings from the flange of the eyelet.
It is an object of the invention to provide an improved grommet of the type mentioned above having means for preventing the washer from falling off from the eyelet's barrel before deformation thereof.
According to the invention this object is achieved with a grommet which is characterized in that the outside of the barrel or the central bore of the washer is provided with a temporary retaining means for preventing the washer from falling off from the barrel when the washer has . been placed thereon.
The features and advantages of the present invention will be better understood from the following description in conjunction with the accompanying drawings in which preferred structural embodiments incorporating the principles of the invention are shown by way of example.
Referring now to Figure 1, there is a preferred form of grommet 10 which is made up from an eyelet part 11 and a washer part 12, both parts being made of a resilient, deformable material such as plastics, rubber and the like. The eyelet 11 includes a cylindrical barrel 13 with one end open and an annular flange 14 extending around the other end or bottom of the barrel 13. The annular flange 14 has a tapered prong 15 for biting engagement with a sheet of fabric F.
According to an important feature of the present invention, there is provided a retaining means 16 for preventing the washer part 12 from falling off from the eyelet part 11 once both parts have been brought into engagement.
The retaining means 16 is embodied in the form of a plurality of discrete projections projecting radially outwardly from the barrel 13 and arranged around thereof. Each projection 16 has a first surface 16a obtusely slanting toward the flange 14 and a second surface 16b acutely slanting toward the open end of the barrel 13 or in a direction opposite to the flange 14. Alternatively, the retaining means may be in the form of an integral annular projection 16' (Figure 1A) of the same cross section as that of the discrete projections of Figure 1.
The washer part 12 is in the form of a circular plate having a central bore 17 which has a diameter nearly equal to the outside diameter of the cylindrical barrel 14 and slightly smaller than an outside diameter defined by the projections 16. A prong 18 similar to the prong 15 extends from the bottom of the washer 12 and similarly functions to anchor the fabric F against movement.
Now, when assembling the eyelet 11 and the washer 12 together, the eyelet 11 is first inserted with its barrel 13 through an opening F1 in the fabric F and then through the bore 17 of the washer 12, when the washer 12 undergoes elastic deformation as the peripheral wall of the bore 17 rides over and past the projections 16. The washer 12 can thus be retained in engagement with the eyelet 11 between the fabric F and the projections 16 until the two grommet parts are assembled in the well known manner as illustrated in Figure 2.
Referring to Figures 3-6 inclusive, there is shown a modified form of grommet which is identical in construction with the above described grommet 10 except for the details of a retaining means embodying the invention and except that there are provided a plurality of prongs 15 and 18 on the eyelet 11 and the washer 12, respectively, and that an annular recess 21 is formed in and around the outer periphery of the barrel 13 of the eyelet 11 at the open end thereof to facilitate the insertion of the eyelet 11 through the fabric F as well as the washer 12. The modified form of retaining means comprises a plurality of radial projections 19 extending radially inwardly from the peripheral edge of the bore 17 in the washer 12 and each having a tapered surface 20 directed toward the eyelet 11. The diameter defined by the radial projections 19 is slightly smaller than the outside diameter of the barrel 13, so that when the eyelet 11 is inserted through the bore 17 of the washer 12, the radial projections 19 are flared up in contact with the outer wall of the barrel 13 in a direction in which the eyelet 11 is inserted and lock the washer 12 against backward movement, thus preventing accidental separation of the washer 12 from the eyelet 11. Because of the structural features of the radial projections 20, the eyelet 11 and the washer 12 upon being assembled as shown in Figure 4 can be retained in position against relative movement, thus ensuring firm setting of the grommet 10 in the fabric F.