BACKGROUND

The present disclosure relates to a screw fastener arrangement comprising a screw fastener, with a head having a ring-shaped washer contact surface and a shank, and at least one washer on the shank of the screw fastener. Furthermore, the invention relates to a washer assembly for a screw fastener.

Fasteners are used for clamping of two or more objects to one another, wherein typically two fasteners are designed to be complementary to one another, such as for example in the case of screw fasteners and thus in the case of a screw and a nut. In order to improve the introduction of force from the underside of the screw head—the same applies for the side of the nut facing the object to be clamped—into the part or parts to be clamped, in many cases washers are inserted between the screw head and the surface of the object against which the screw head is to be clamped. These washers can be flat washers or also lock washers. Lock washers are used when undesirable loosening of such a screw fastener should be prevented.

In order to simplify assembly of a screw fastener on site and in order to prevent situations where, during clamping of a plurality of fasteners, the user has forgotten to arrange a washer—either as a flat washer or as a lock washer—below the screw head, screws have been developed which have a washer retained undetachably on the screw shank. This is achieved in that the washer to be arranged below the screw head is fitted onto the screw shank, which is unrolled with regard to the thread formation, and only after this fitting the thread is rolled. The external diameter of the rolled thread is greater than the diameter of the opening of the washer, which, due to the thread, is then located on the shank below the screw head and thus is undetachably connected to the fastener.

A disadvantage of this design is that the washers are located on the screw shank during the thread rolling process. If these washers are lock washers, there is a danger that securing elements of the washer are damaged during the rolling of the thread between the rolling plates. In the case of flat washers, grooves or other kinds of damage can ensue, so that in this way the contact surface provided is reduced. Moreover, the production of such a screw with a washer connected thereto is economically viable only if a sufficiently large number of screws are produced. It should also be borne in mind that screws with one and the same nominal diameter are produced with varied lengths. This means that a manufacturer must produce and stock corresponding quantities of screws of different lengths with corresponding quantities of washers connected thereto. For reasons of cost, this previously known concept could not be employed in small batches.

The foregoing examples of the related art and limitations therewith are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification and a study of the drawings.

SUMMARY

The following embodiments and aspects thereof are described and illustrated in conjunction with systems, tool and methods which are meant to be exemplary and illustrative, not limiting in scope. In various embodiments, one or more of the above described problems have been reduced or eliminated, while other embodiments are directed to other improvements.

Starting from this discussed prior art, one aspect of the present disclosure is to propose a fastener with at least one washer connected to the fastener and having an opening, by which fastener the demonstrated disadvantages of the prior art discussed above are at least largely avoided.

This is achieved by a fastener in which a coupling sleeve is in the opening of the at least one washer through which the shank passes, the coupling sleeve having a U-shaped profile which opens radially outwards and is formed by two flanges spaced from each other and protruding radially outwards, the coupling sleeve being held interlockingly with the at least one washer by the flanges in the direction of the longitudinal axis of the washer opening, which coupling sleeve has a plurality of clamping catches projecting radially inward and elastically adjustable in the direction of their longitudinal axis against the interior wall of the coupling sleeve which, using their free end, engage in an undercut of the screw fastener, acting in a longitudinally axial direction to the coupling sleeve.

The at least one washer of this screw fastener is equipped with a coupling sleeve which is held interlockingly on the at least one washer in the longitudinal direction thereof. The coupling sleeve has a plurality of clamping catches projecting radially inwards. These catches are elastically adjustable in the longitudinal direction of the coupling sleeve against the inner wall of the coupling sleeve. The adjustability of the clamping catches typically results from the material used for the production of the coupling sleeve. For connection of the washer to the fastener, these clamping catches engage in an undercut acting in a longitudinally axial direction of the fastener. They may be, for example, two adjacent thread pitch turns of the shank of the screw fastener. During the engagement in the undercut of the screw fastener, the clamping catches act as latches. As a result of the elastic adjustability of the clamping catches, such a washer can be pushed onto the shank of a screw after the thread has been rolled. The clamping force with which the clamping catches are fixed in such a groove, for instance in a thread, is sufficiently high that the washer cannot be removed during a conventional handling of the screw fastener. It is certainly possible to design the coupling sleeve so that the washer can be withdrawn again by the use of some force from the fastener, for example the screw shank. According to one embodiment, it is provided that the clamping catches are inclined counter to their fitting direction on the shank of a screw, and then engage like barbs in the undercut acting in a longitudinally axial direction. Then the force required for fitting the washer onto the threaded shank is less, typically significantly less than the force which would have to be applied in order to remove the washer from the screw shank again. This removal is generally not necessary in any case. In some embodiments, the radial length of the clamping catches in an inclined design thereof can be so great that a removal of the washer assembly composed of the washer and the coupling sleeve is only possible with a plastic deformation of the clamping catches or destruction thereof.

Such a washer can also be fitted, for example, on a screw fastener designed as a nut, if this washer has a circumferential groove following its washer contact surface. Then the clamping catches engage in this groove.

An advantage of this design is that a screw with its thread can be produced completely independently and without taking into consideration a washer located on the screw shank. Moreover, in this design, only those screws which should be equipped with such a detachable washer are then equipped with a washer. Therefore, such a lock washer with its coupling sleeve is also suitable to a particular degree for creating fasteners with washers retained thereon in small batches.

The coupling sleeve surrounds the at least one washer with its flanges in the longitudinal direction of the opening in the washer. As a result, the coupling sleeve is connected to the washer interlockingly in said direction.

Ultimately, any washer can be connected to a fastener by such a coupling sleeve. This also includes lock washers of various types. In one embodiment, the surrounding of the at least one washer by the flanges of the coupling sleeve protruding outwards in the radial direction is used to hold together two washers of a wedge lock pair. In many cases, such wedge lock washers are glued together to form a pair of wedge lock washers, in order to ensure that these washers are assembled with their sides facing one another correctly. This gluing is not necessary when such a coupling sleeve is used, since the two wedge lock washers are held together by the flanges of the coupling sleeve that project over the washer surfaces which face away from one another.

In principle, the clamping catches can be arranged in different positions in relation to the height or longitudinal extent of the coupling sleeve. According to one embodiment, these catches are located at the upper end of the coupling sleeve, namely at the end which faces the washer contact surface of the fastener. If the fastener is a screw, then in such an embodiment the clamping catches engage in the thread run-out and thus in the space between the underside of the screw head and the start of the thread. Such an arrangement is advantageous if the clamping catches are inclined counter to the fitting movement direction for connection thereof to a fastener. Then the arrangement of the clamping catches on one end of the coupling sleeve simultaneously constitutes a coding and indicates which side of the arrangement of washer/washers and coupling sleeve is to be fitted to a fastener first. A fitting coding can also be provided in another way.

The clamping action of the clamping catches can be adjusted by the number of clamping catches which are typically arranged circumferentially with the same angular spacing relative to one another, the material of the coupling sleeve and thus typically also the material of the clamping catches, the connection geometry of the clamping catches to the other components of the coupling sleeve and/or the angle value over which each clamping catch extends. The greater this angle value is, the more rigidly a clamping catch reacts regarding its adjustability in the longitudinal direction of the opening of the coupling sleeve and the more force that must be applied in order to move it so far that the washer can be removed from the fastener. The connection geometry of the clamping catches to the other components of the coupling sleeve can be provided, for example, by a groove in order to achieve the required adjustability.

Even if, typically, the clamping catches are arranged at one and the same height with regard to the height of the coupling sleeve, it is possible to arrange the catches at different heights and thus in different positions with regard to the longitudinal extent of the coupling sleeve. This presupposes that the coupling sleeves are then connected to a screw fastener which has corresponding undercuts at different heights with regard to the longitudinal extent of the coupling sleeve. This configuration applies in the case of a screw being the screw fastener because of the thread extending over a certain longitudinal extent.

In the radial direction, the clamping catches preferably, but not necessarily, extend as far as the base of the groove of the fastener forming such an undercut, which is the screw core in the case of a screw. Clamping with such clamping catches is particularly effective if they are additionally inclined like barbs counter to the fitting direction. An adjustment of the clamping catches for removing the washer is then blocked by the base of the groove, so that the washer with its coupling sleeve can no longer be removed from the fastener without damage or destruction. Such a configuration of the coupling sleeve also enables the introduction of a groove in the root region of the clamping catches in order to achieve an adjustability counter to the fitting direction.

The coupling sleeve is preferably, but not necessarily, made of metal or plastic. In order to form the washer with its coupling sleeve, the coupling sleeve will be made of a material which is suitable with regard to the material of the fastener or fasteners and with regard to the clamped objects.

Another advantage of such a washer equipped with a coupling sleeve or such a multi-washer arrangement, for example a pair of wedge lock washers, equipped with a coupling sleeve is that the coupling sleeve can also be used as a seal. In such a case, the height of the coupling sleeve in the unclamped state of the fastener is greater than the thickness of the at least one washer, so that the outer faces of the flanges facing away from one another in the longitudinal direction are pressed onto the washer contact surfaces of the fastener—on the one hand—and the surface of the object to be clamped—on the other hand. In the case of a clamped fastener, its washer contact surface acts directly on the abutment and is clamped against this abutment. In this respect, the pressing force of the sealing surface results from the elastic restoring force of the seal and/or the coupling sleeve. Such a configuration of the coupling sleeve with sealing functionality allows an encapsulation of the thread and the thread opening of a fastener with the result that lubricant introduced therein remains permanently therein and is not washed out. For this reason, such a washer assembly, in which the coupling sleeve simultaneously forms a seal, can also be used for applications in which the thread must be encapsulated so that lubricants contained therein do not escape or are not washed out, for instance, by cleaning fluid. Thus, these fasteners can also be used in plants which process food products. Such fasteners can also be released again without problems, even after many years.

Because of the described sealing functionality of the coupling sleeve, washer assemblies, for example two wedge lock washers arranged as a pair of wedge lock washers, can be clamped and sealed without restricting the movability of the wedge lock washers with respect to one another, which is necessary for releasing such a pair of wedge lock washers, particularly in the axial direction.

The sealing effect of such a coupling sleeve can result from the material of the coupling sleeve itself. It is also possible to form a metallic seal, if the coupling sleeve is made of metal. Typically, in such a case, the material of the coupling sleeve is softer than that of the adjacent washer contact surface of the fastener and of the object to be clamped. It is also certainly possible to apply a sealing ring made of a different material, for example silicone (silicone bead), to the relevant front faces of the flanges of the coupling sleeve, or even to provide a separate sealing ring, preferably held by the coupling sleeve.

If the coupling sleeve simultaneously serves as a seal, the flanges protruding outwards in a radial direction are configured to be circumferential. If the coupling sleeve does not have a sealing function, the flanges can also be provided by a plurality of flange segments spaced apart from one another.

In addition to the exemplary aspects and embodiments described above, further aspects and embodiments will become apparent by reference to the accompanying drawings forming a part of this specification wherein like reference characters designate corresponding parts in the several views.

