Press fastener

Abstract: The press fastener eyelet is formed by a substantially annular, plastic moulding (1) having said central perforation (5) and comprising a round ball reception area (2) and a temporarily widenable locking area (3) which tapers towards the insertion end for the press fastener ball and extends roughly coaxially to said ball reception area (2). Said plastic body comprises a ring flange-like outer edge, to which is connected in axially displaced manner the central area having the central perforation. Moreover, an all-round groove (7) increasing the resilient action of the locking area is provided in the ring flange-like outer edge of the plastic body radially outside the locking area (3), with the locking area (3) being constructed polygonally. The plastic moulding may advantageously be moulded from POM (polyoxymethylene).

Description: The invention relates to a press fastener with a male member in the form of a metal press fastener ball fixed to a first supporting web and a female member comprising a shaped plastic body firmly connectable to a second supporting web and which has an expandable locking area tapering towards the insertion end for the press fastener ball and with which is associated in spaced manner an opening increasing its resilient action and thus permitting its expansion. In the case of the prior art press fasteners (DE 39 18 375 A1, EP 401 574 A2) the female member comprises a plurality of elements, usually punching steel parts, which are interconnected to form a unit and having a spring ensuring the maintaining of the press fastener ball and engaging behind the ball head. These press fasteners have a complicated construction, are correspondingly difficult to manufacture and disadvantageously only allow a small number of closing and opening cycles. It is also known to construct the female member in the form of an eyelet container shaped from sheet brass and in whose marginal area is mounted an expandable plastic ring in such a way that during the insertion of the press fastener ball into the female member the temporarily deformed plastic ring engages behind the press fastener ball. In place of the polygonal ring construction it is also known to use a circular plastic ring, which is provided on its circumference with radially projecting cams. Also with such constructions an operationally essential part is played by the relatively complicated sheet metal eyelet container forming the female member and also the sought large number of closing and opening cycles cannot be achieved. In a known press fastener of the aforementioned type (DE 19 44 254) , the female member comprises an oval, flat, shaped plastic body with a central through hole for the male member. This through hole has curvature parts spaced from one another and said spacing is so matched to the spacing of the areas cooperating therewith of the "insertion curvature behind the ball head" that positive engagement is ensured in the closed position. Such a locally limited position of the "insertion opening" necessarily means that it is subject to precision fluctuations, which are associated with corresponding positive engagement fluctuations. For ensuring an adequate closure quality in the known fastener it is necessary to strictly respect the predetermined dimensions. This naturally involves higher manufacturing effort and therefore correspondingly higher costs. In addition, the stressed, positive engagement of the ball head in the closed position leads to there being no relative mobility of the fastener parts in the coupled state. Also in the case of the further known press fastener (DE 18 07 760), whose two parts are made from plastic, no clearance is provided after the coupling process between the male and female members, so that they are not movable relative to one another. The flange parts of the male and female members come into reciprocal contact in the coupled state, so that as a result a relative mutual rotation is prevented, but this is favourable in order to avoid material deformations and ensure a straightening of the press fastener panel. The problem of the invention is to so further develop the press fastener of the aforementioned type that, despite a simpler construction, an inexpensive construction can be attained, which permits a large number of opening and closing cycles and also relative rotations in the closed position. According to the invention this problem is solved in that the shaped plastic body of the female member is substantially annular and comprises a ring flange-like outer edge to which is connected in axially displaced manner a central area connectable to a rivet shank emanating from a rivet cap and that in the ring flange-like outer edge of the plastic body radially outside the locking area is provided the opening, in the form of a circumferential groove, which increases the resilient action of the locking area for the temporary expansion thereof. This functionally essential shaped body can be rationally and therefore inexpensively produced in a plastic injection moulding process. In conjunction with the metal press fastener ball of the male member, it guarantees a very large number of opening and closing cycles and as a result of the only temporary expansion during insertion a relative rotation is possible in the closed state. In spite of the large number of cycles, a particularly attractive and long lasting appearance is achieved if a metal cup is associated with the shaped plastic body on the side facing the insertion end and which has an opening only leaving free the insertion end with the locking area. Said metal cup can be connected in random manner to the plastic body. It has proved particularly appropriate for the metal cup to be connected to the outer edge of the plastic body by the inward beading of its outer edge onto the same. The locking area can be circular. However, in a particularly appropriate manner it is given a polygonal construction aiding the temporary expansion and the locking area appropriately has on the radial inside four circumferentially uniformly distributed projections. Polyamide or polyester can be used for the manufacture of the plastic body. However, it has been found that particularly high opening and closing cycles, namely at least 50,000, can be achieved without there being any detectable change of the forces to be expended, if the shaped plastic body is made from POM (polyoxymethylene). Press fasteners with such a female member are particularly suitable for long-life commodities, e.g. purses and are more particularly used in the leather industry. Naturally the press fastener eyelet, i.e. the plastic body and the metal cup are, in accordance with needs, given different colours. A construction with particularly attractive colouring is obtained if the metal cup and the plastic body are given a gold colour. Further details, advantages and characteristic features will be apparent from the following description and the attached drawings, wherein Figs. 1 and 2 are bottom plan views of two different embodiments of a press fastener eyelet.forming a female member, Fig. 3 a vertical sectional view of the female member shown in figs. 1 or 2, Fig. 4 a vertical sectional view of the moulding shown in Fig. 3, together with a metal cup also shown in a sectional view - before being connected. Fig. 5 is a vertical sectional view of the moulding and the metal cup shown in Fig. 4 - after having been connected -, Fig. 6 is a vertical sectional view to illustrate the moulding of Fig. 5 which has been fitted with a metal cup - after the ball member of the press fastener ball has been inserted -, Fig. 7 is a vertical sectional view of the moulding-metal cup unit before being fixed to a supporting web by means of a rivet comprising a rivet cap and a rivet shank, and Fig. 8 is a vertical sectional view of the individual elements illustrated in Fig. 7, after having been mutually connected and fixed to the carrier web. As seen from the drawings, the illustrated press fastener eyelet essentially comprises an annular plastic moulding 1 having a round ball reception area 2 and a locking area 3 extending roughly coaxially thereto and tapering towards the insertion end for the press fastener ball (not shown), said locking area 3 being temporarily widenable. Said plastic body 1 comprises a ring flange-like outer edge 4 to which is connected in axially displaced manner the central area 6 having the central perforation 5. An all-round groove 7 increasing the resilient action of the locking area 3 is provided in the ring flange-like outer edge 4 of the plastic body 1 radially outside the locking area 3. Practically, said groove 7 is a so-called sparing allowing the locking area 3 which tapers towards the insertion end for the press fastener ball to deflect radially. As shown in Fig. 1, the radially inner periphery 8 of the locking area 3 is of round shape, whereas in the embodiment of Fig. 2 it is polygonal. Further, as shown in Fig. 2, said locking area 3 has four projections 9 being circumferentially uniformly distributed. Suitable materials for producing the plastic moulding 1 are polyamide or polyester. When using POM (polyoxymethylene), particularly high closing and opening cycles in the order of 50,000 or more may be achieved. As illustrated in Figs. 4 et seqs, with the plastic body 1 is associated, on the side facing the insertion end, a metal cup 10 having an opening 11 only freeing the insertion end. Said metal cup 10 can be connected, after insertion of the ring flange-like outer edge 4, with the outer edge of the plastic body 1 by inwardly beading its outer edge 12. The metal cup 10 may advantageously be coloured with any required shades of colour, e. g. with a gold shade corresponding to the gold shade-coloured plastic body. Fig. 7 shows a press fastener eyelet with all its elements prior to fixed it to a carrier web 13, such as a leather web or textile web. To fix the press fastener eyelet, which essentially is comprised of the annular plastic moulding 1 and the metal cup 10, to the carrier web 13, a cap rivet having a rivet cap 14 and a rivet shank 15 emanating from said cap is provided in known manner. Fig. 8 shows the press fastener eyelet being fixed to the carrier web. As can be seen, the rivet cap 14 is fixedly connected to the carrier web 13, namely, by deformation of the rivet shank 15 passing not only through the carrier web but also through the central perforation 5 of the plastic body 1 and being widened inwardly and upwardly.

Claims: Press fastener with a male member in the form of a metal press fastener ball fixed to a first supporting web and female member (110) comprising a shaped plastic body (1) firmly connectable to a second supporting web (13) and which has an expandable locking area (3) tapering towards the insertion end for the press fastener ball , characterized in that the shaped plastic body (1) of the female member is substantially annular and comprises a ring flange-like outer edge (4) to which is connected in axially displaced manner a central area (6) connectable to a rivet shank (15) emanating from a rivet cap (14) and that in the ring flange-like outer edge (4) of the plastic body (1) radially outside the locking area (3) is provided an opening, in the form of a circumferential groove (7), which increases the resilient action of the locking area for the temporary expansion thereof. Press fastener according to claim 1, characterized in that with the shaped plastic body (1) on the side facing the insertion end is associated a metal cup (10) with an opening (11) only leaving free the insertion end with the locking area (3). Press fastener according to claim 1 or 2, characterized in that the locking area (3) is provided with a polygonal construction aiding temporary expansion. Press fastener according to claim 3, characterized in that the locking area (3) is provided on the radial inside with four circumferentially uniformly distributed projections (9). Press fastener according to one of the claims 1 to 4, characterized in that the shaped plastic body (1) is formed from POM (polyoxymethylene). Press fastener according to claim 1, characterized in that the metal cup (10) is connected to the outer edge (4) of the plastic body (1) by the inward beading of its outer edge (12) onto the same. Press fastener according to claim 2 or 6, characterized in that the metal cup (10) and the plastic body (1) is e.g. coloured gold.

Inventors: PFERDEHIRT THOMAS, PFERDEHIRT, THOMAS
Applicants: YKK EUROP LTD, YKK EUROPE LTD.
Application year: 1999
Main classification: A44B17
IPC codes: A44B17