Patent Description:
The invention has been developed with particular regard to an improved press-stud which is provided with an anti-disconnection system which prevents the unbuttoning thereof in the presence of a transverse traction.

Press-studs are generally known and comprise a female element and a male element which can be mutually connected in a releasable manner by means of an elastically deformable engagement member, typically a ring, which is mounted in the female element, in a receiving seat. There can be selectively inserted in the receiving seat, in a connection direction, at least one portion of the male element in order to change from an unbuttoned configuration, in which the male element and the female element are separated and disconnected, to a buttoned-up configuration, in which the two male and female elements are connected together. A stud of this type is known from <CIT>.

There are known various press-studs of the type indicated above which are buttoned up and unbuttoned by applying a pressure or a traction to the two male and female elements, respectively, in the connection direction. A problem of the known studs is that they can also become unfastened if they are subjected to a lateral traction, that is to say, traction directed in a direction transverse to the connection direction. For this reason, they cannot be used in applications in which the traction in a transverse direction is significant, for example, in order to close trousers or to grip two portions of handles or straps of bags and purses.

In order to solve this problem, the same Applicant has in the past developed a snap fastener, to which the patents <CIT> and <CIT> relate, which is able to resist without becoming unfastened even in the presence of lateral traction forces. A first example of such studs provides for the head of the male element to terminate flat and with a central hole and for the female element to have, inside the housing for the male element, a corresponding tubular member which widens in an annular disconnection prevention extension piece and which is inserted in this hole in the head of the male element. In the event of lateral traction, the annular extension piece remains engaged inside the head of the male element, preventing disengagement.

The stud which is formed in this manner functions effectively, but the presence of the head with a hole and the cylindrical member cause the stud, in the open state, to be able to become caught, for example, in a clothing item or other objects. Furthermore, the stud, in the open state, has a number of cut edges made from sheet metal in view, which is not very attractive from an aesthetic point of view. Particularly for applications in high-end clothing items or accessories, a refined appearance without any cut edges in view is preferable. It is then be considered that the known stud is larger than a conventional snap fastener.

Another example of a stud which withstands unfastening when it is subjected to a lateral traction and which is described in the above-mentioned patents from the present Applicant has a male element, the head of which comprises an annular flap which is directed outwards and which forms a disconnection prevention extension piece which is arranged near the base of the male element. When a force is applied in a transverse direction, this extension piece engages with an opening of the female element, making it impossible to disengage it. Even if this variant is completely functional, it has the same disadvantages as the first one, also having an edge of cut sheet metal in view. This stud is also rather bulky and relatively heavy.

An object of the invention is to solve the problems of the prior art. In particular, an object is to provide a snap fastener which does not accidentally become unbuttoned when it is subjected to a transverse traction but which is convenient and easy to fasten and unfasten intentionally. Another object is to provide a snap fastener which is compact and small without it compromising the disconnection prevention characteristics thereof. Another object is to provide a snap fastener which is aesthetically attractive, highly refined in the portions which are in view even when it is unfastened. Another object is to provide a stud which does not run the risk of becoming caught in clothing or objects. It is further intended to provide a snap fastener which requires only minimal modifications to the production processes with respect to conventional press-studs. Another object is to provide a stud which is economical, simple, reliable in use and safe.

According to a first aspect, there is described a press-stud which comprises a male element and a female element. The male element and female element may be able to be connected to each other in a connection direction. The female element may comprise a cavity in which an elastic retention member can be received. A disconnection prevention projection can be provided in the cavity.

The male element may comprise an abutment portion, from which there may extend a connection portion. A narrowed portion and a disconnection prevention widened portion may be formed on the connection portion. The disconnection prevention widened portion can be located at the opposite side of the abutment portion with respect to the narrowed portion.

In a connected configuration of the press-stud, that is to say, when the male element and the female element are connected to each other and the stud is fastened, the connection portion may be located inserted in the cavity of the female element with the elastic retention member arranged around the narrowed portion. A transverse movement of the male element with respect to the female element by a predetermined value with respect to the connection direction may bring the press-stud into a blocked configuration. In the blocked configuration, the disconnection prevention widened portion can interfere with the disconnection prevention projection of the female element. In the blocked configuration, the abutment portion of the male element can be in contact with an external portion of the female element.

In the connected configuration of the press-stud, the abutment portion can face the external portion of the female element.

Such a configuration allows the production of a press-stud which is particularly compact so as also to be able to be used at locations where a very small stud is required, for aesthetic and/or technical reasons. Furthermore, the stud formed in this manner does not have any edge made from sheet metal in view which could be annoying, possibly even sharp-edged or in any case aesthetically unattractive.

It is further known that such a snap fastener is particularly suitable for use in a strap of a bag or purse which is intrinsically subjected to a traction as a result of the effect of the weight itself of the purse: when the purse is being used, the weight of the purse causes the stud to reach a blocked connected configuration, in which it cannot be disengaged in any manner. The stud thereby ensures that the strap cannot become disengaged regardless of the weight which the content of the purse can reach: in fact, it is necessary to bring back the stud into an unfastenable connected configuration by removing the tension which is applied to the strap before being able to disengage the stud.

According to another aspect, in a press-stud the connection portion of the male element has a chamfered surface. The term "chamfered" is intended here to be understood to mean a surface without any sharp edges, a smoothed surface. It is thereby prevented from having cracks or recesses, in which oxide can become formed, dirt can become deposited or in which ties, strings, fabrics, etc., can become caught.

Another interesting advantage is that the stud according to the invention may appear very similar, with regard to the visible components, to a conventional stud because the disconnection prevention widened portion of the male element is scarcely visible and the disconnection prevention projection of the female element is completely hidden.

According to another aspect, there is described a press-stud in which the disconnection prevention widened portion of the male element can interfere with a disconnection prevention projection of the female element which is interposed between a base of the female element, for support on a substrate, and a housing for the elastic retention member.

Advantageously, the female element may comprise a tubular portion for forming the cavity for receiving the connection portion. The disconnection prevention projection of the female element can be formed by a narrowed portion in the tubular portion.

There is further described a press-stud in which the elastic retention member is an elastic ring. The elastic ring may comprise an internal portion which can grip and retain the connection portion of the male element and a plurality of external protuberances. Each external protuberance may be elongate and curved. An end portion of each protuberance can be arranged tangent to an edge of a receiving seat for the elastic ring. Advantageously, the external protuberances can be elastically deformed. Particularly when the stud is in a blocked connected configuration, at least one external protuberance can be deformed and can apply a force to the internal portion which tends to align the male element and the female element with each other. A stud which is configured in this manner can be readily disengaged once the application of a transverse force has been interrupted because the components automatically become re-aligned precisely in order to allow the stud to be unblocked.

According to another aspect, there is further described a press-stud in which the connection portion of the male element can terminate in a head of a first diameter. The disconnection prevention widened portion provided on the male element can be formed by a step which is provided on the tubular member and in which the tubular member changes from the first diameter to a second diameter, which is smaller than the first diameter. The step may have a rounded profile. In this configuration, it is possible to have a maximum interference between the disconnection prevention projection and the disconnection prevention widened portion because it allows a minimum gap to be provided between the diameter of the head and the internal diameter of the hole which is defined by the disconnection prevention projection of the female element. When the gap between the two diameters is at a minimum, the disconnection prevention projections interfere over a great portion of the circumference thereof, making the connection more effective.

There is further described a stud, in which, in a blocked connected configuration, the axes of the male element and the female element are kept substantially parallel with each other.

Additional features and advantages will be appreciated from the following detailed description of a preferred embodiment of the invention with reference to the appended drawings, which are provided purely by way of non-limiting example and in which:.

With reference now to <FIG>, a press-stud <NUM> comprises a male element <NUM> and a female element <NUM>. During use, the two elements are fixed to two respective substrates, such as, for example, fabric flaps, hides, plastics material or the like, in order to be able to fasten them to each other. The male and female elements can be fixed to the respective substrates according to known methods which are therefore not described in detail, for example, by means of riveting, pinning, stitching and other techniques which are generally known in the field.

The male element <NUM> which can be seen in detail in <FIG> comprises a disc-like base <NUM> with a face <NUM> which is intended to be supported on the substrate during use. The base <NUM> is preferably provided with a bored cylinder <NUM> which is coaxial with the disc-like base <NUM> for the passage, for example, of a member for fixing to the substrate, which is not illustrated, for example, a rivet or the like. The bored cylinder is particularly suitable if the stud is intended to be applied to a thick substrate, such as, for example, leather. Naturally, the possibility of simply providing a hole in the disc-like base in place of the bored cylinder <NUM> is not excluded.

A connection portion <NUM> projects from the base <NUM> of the male element <NUM> at one face <NUM> of the base <NUM> opposite the face <NUM> which is intended to be supported on the substrate during use. The connection portion <NUM> is intended to connect the male element <NUM> to the female element <NUM>. The connection portion <NUM> comprises a substantially tubular member <NUM> which is generally narrower than the disc-like base <NUM> and which projects with respect to the disc-like base <NUM> from the face <NUM>. At the end of the tubular member opposite the disc-like base <NUM>, the tubular member <NUM> has a head <NUM> with a diameter D1. On the lateral wall <NUM> thereof, the tubular member <NUM> is provided with a first step <NUM> and a second step <NUM>. The term "step" is intended to be understood to be the passage from a first diameter to a second diameter as a result of the effect of a narrowing or widening.

In greater detail, at the second step <NUM>, the tubular member <NUM> widens from a diameter D3 of a narrowed portion <NUM> to a diameter D2', which is greater than D3. At the first step <NUM>, the tubular member <NUM> widens from a diameter D2 to the diameter D1 of the head <NUM>, which is greater than D2. In the case depicted, D2= D2' so as to construct a male element which is as similar as possible to a male element of a conventional stud and to contain the number of processing operations. However, it should not be excluded that D2' is greater or smaller than D2. The first step <NUM>, as described in greater detail below, forms a disconnection prevention widened portion <NUM> or disconnection prevention projection.

The female element <NUM> which is shown in detail in <FIG> comprises a base <NUM> which is substantially planar with a face <NUM> which is intended to be supported on the substrate during use and from which there extends a tubular portion <NUM> which forms a cavity or receiving seat <NUM> for the connection portion <NUM> of the male element <NUM>. The base <NUM> is preferably provided with a central hole <NUM> in order to fix the element to a substrate, for example, for the passage of a fixing member, which is not illustrated, such as a rivet or the like.

The tubular portion <NUM> has a localized narrowed portion <NUM> which forms a disconnection prevention projection <NUM> which is able to cooperate, as explained below, with the disconnection prevention projection <NUM> of the male element <NUM>, forming together therewith a blocking device <NUM> of the press-stud of the present invention. The tubular portion <NUM> further widens so as to define a receiving seat <NUM> for an elastic retention member.

an elastic retention member which is preferably an elastic ring <NUM> is received in the receiving seat <NUM> of the female element <NUM>. The receiving seat <NUM> is closed by an annular retention edge <NUM>, which prevents the elastic ring <NUM> from leaving the receiving seat <NUM>. The annular retention edge <NUM> is preferably constructed by means of a shaped metal sheet. The elastic ring <NUM> can better be seen in <FIG>, where the female element is depicted without an annular retention edge <NUM>.

The elastic ring <NUM> preferably comprises an internal portion <NUM> which is able to grip and retain the connection portion <NUM> of the male element <NUM> at the narrowed portion <NUM> and a series of external protuberances <NUM>. Each external protuberance <NUM> is preferably elongate and folded; an end portion <NUM> is arranged to be tangent to an edge <NUM> of the receiving seat <NUM>. The protuberances are compressible, deformable and elastic. The internal portion <NUM> of the elastic ring <NUM> can thereby move laterally in translation inside the receiving seat <NUM> but tends to be substantially centred inside the receiving seat by the elastic force of the external protuberances <NUM>. The internal portion <NUM> preferably has notches <NUM>.

During use, the male element <NUM> and the female element <NUM> of the press-stud <NUM> are fixed to two substrates which it is desirable to fasten, respectively. As known, in order to fasten the press-stud <NUM>, the male element <NUM> is positioned with a longitudinal axis A thereof substantially coincident with the axis B of the female element <NUM>. The head <NUM> of the male element <NUM> is supported on the opening of the receiving seat <NUM> of the female element <NUM>. The two male <NUM> and female <NUM> elements are pressed against each other in a connection direction which is substantially parallel with the longitudinal axis B of the female element with such a pressure as to allow the connection portion of the male element <NUM> to deform the elastic ring <NUM> sufficiently to allow the passage thereof. When the elastic ring <NUM> passes the second step <NUM>, it narrows elastically around the narrowed portion <NUM> of the connection portion, retaining the connection portion in the receiving seat <NUM> of the female element in an unfastenable buttoned-up configuration of the press-stud <NUM>.

In this unfastenable buttoned-up configuration, which is shown in <FIG>, the elastic ring <NUM> presses against the connection portion <NUM> and the second step <NUM> prevents the release of the connection portion under light loading conditions. It is known that, in this configuration, the male element <NUM> and female element <NUM> are supported against each other, with the face <NUM> of the disc-like base <NUM> of the male element <NUM> in contact with the annular retention edge <NUM> of the female element and there is no axial play.

Now with reference to <FIG>, if it is desirable to intentionally unfasten the stud, therefore by intentionally disconnecting and separating the two male <NUM> and female <NUM> elements, there is applied a traction which is directed towards moving the two male <NUM> and female <NUM> elements apart from each other, as for conventional press-studs. The movement is normally of the combined axial and rotational type. The traction applied brings about a widening of the elastic ring <NUM> until sufficient space is generated between the two elements so that the male element <NUM> rotates about a fulcrum <NUM> which has been generated in a contact zone between the face <NUM> of the disc-like base <NUM> of the male element <NUM> and the annular retention edge <NUM> of the female element <NUM>. The force applied therefore promotes a minimum outward travel in an axial direction of the male element, including by a few tenths of millimetres, and subsequently the rotation thereof. With a movement which is both axial and rotational, the connection portion is removed from the elastic ring, bringing about the passage through the elastic ring <NUM> which is widened to this end, before the second step <NUM> and then also the first step <NUM>, until complete disengagement of the male element <NUM> from the female element <NUM>.

The stud which is in the unfastenable blocked configuration of <FIG> can be subjected to a lateral tension, that is to say, to a tension which is substantially transverse with respect to the connection direction. In this case, the female element <NUM> and the male element <NUM> tend to move laterally in translation with respect to each other, as indicated by the arrows F1 and F2 in <FIG>. If the force is sufficiently intense to deform the external protuberances <NUM> of the elastic ring, the internal portion of the elastic ring and the tubular member <NUM> received therein move laterally with respect to the centred position in the receiving seat. Following this movement, the external protuberances <NUM>' of the elastic ring <NUM>, which are located at the side towards which the male element is urged, are urged against the internal wall of the receiving seat and become deformed. In the deformed configuration, which can be seen in the Figure, they apply a force counter to the force which is applied to the stud, which tends to bring back the tubular member <NUM> into the centred position in the receiving seat. When the transverse tension is stopped, therefore, the male element and female element are again aligned as a result of the effect of the external protuberances <NUM>' which tend to take up the original form thereof again.

In the laterally moved position of the tubular member <NUM>, in which the axes A and B of the male element <NUM> and the female element <NUM> are different and substantially parallel with each other, there is brought about a blocked connected configuration of the press-stud. In this configuration, the blocking device <NUM> is actuated: the two disconnection prevention projections <NUM> and <NUM> of the male element <NUM> and of the female element <NUM>, respectively, are positioned in an undercut arrangement and interfere with each other in the event of an attempt to unfasten the press-stud. As <FIG> shows, in fact, a portion of the female element <NUM> is inserted in a recess of the male element, making it impossible to move apart the two male and female elements in an axial direction and therefore to unfasten the stud. In greater detail, a portion of the female element <NUM> contained between the support face against the male element <NUM> and the narrowed portion <NUM> is inserted in a recess of the male element which is delimited by the face of the base <NUM> of the male element which faces the female element, which therefore acts as an abutment portion, and by the disconnection prevention projection <NUM>. The insertion is preferably carried out without any play and in any case only with the play necessary for allowing the stud to change from the unfastenable connected configuration to the blocked connected configuration, and vice versa.

With there being minimal play, if not no play at all, between the two elements in this configuration, they can neither rotate with respect to each other nor can they be moved apart in an axial direction, as described above for the unfastenable connected configuration. Therefore, the two elements remain blocked in the blocked connected configuration until the transverse force applied to the two elements is stopped. When the force stops, the elastic force of the disconnection prevention projections <NUM>' brings back the male element <NUM> and female element <NUM> into the unfastenable connected position, in which the respective longitudinal axes are substantially coincident, as in <FIG>. In this configuration, the disconnection prevention projections do not interfere with each other and therefore, as seen above, the stud can be unfastened.

It may be noted that, in the blocked connected configuration, the axes A and B of the male and female elements are kept substantially parallel and cannot rotate relative to each other.

Preferably, the diameter D1 of the connection portion, that is to say, the greatest diameter between the two diameters D1 and D2, between which the first step <NUM> is defined, is slightly smaller than the diameter D4 of the tubular portion <NUM> at the narrowed portion <NUM>. As a result of a reduced difference between D1 and D4, the disconnection prevention projections interfere with each other, in the blocked connected configuration, in an extensive portion of the circumference. <FIG> shows in detail the positioning with an undercut arrangement of the two disconnection prevention projections <NUM> and <NUM> of the male element <NUM> and the female element <NUM>, respectively. In particular, the respective disconnection prevention projections <NUM>, <NUM> interfere with each other along an arc defined by an angle α and which is defined in the plane perpendicular to the axis B of the female element <NUM> and with the vertex in the same axis B. The angle α is at least <NUM>° and, more preferably, at least <NUM>°.

Claim 1:
A press-stud comprising a male element (<NUM>) and a female element (<NUM>) which can be connected to each other in a connection direction,
- wherein the female element (<NUM>) comprises a cavity (<NUM>) in which an elastic retention member (<NUM>) is received and in which a disconnection prevention projection (<NUM>) is provided,
- wherein the male element (<NUM>) comprises an abutment portion (<NUM>), from which there extends a connection portion (<NUM>), on which there are formed a narrowed portion (<NUM>) and, at the opposite side of the abutment portion (<NUM>) with respect to the narrowed portion (<NUM>), a disconnection prevention widened portion (<NUM>),
- wherein, in a connected configuration of the press-stud (<NUM>), the connection portion (<NUM>) is inserted in the cavity (<NUM>) of the female element (<NUM>) with the elastic retention member (<NUM>) arranged around the narrowed portion (<NUM>),
- wherein a transverse movement of the male element with respect to the female element by a predetermined value with respect to the connection direction brings the press-stud (<NUM>) into a blocked configuration, in which the disconnection prevention widened portion (<NUM>) interferes with the disconnection prevention projection (<NUM>) of the female element (<NUM>) and the abutment portion (<NUM>) of the male element comes into contact with an external portion (<NUM>) of the female element (<NUM>).