FIELD OF THE INVENTION

The present invention relates to a composite screw formed by at least two halves that are joined together, creating a hollow body, such that the weight of the screw is reduced and, by virtue of the structural arrangement thereof, good mechanical properties are conferred thereon.

PRIOR ART

There are multiple screws that may differ from one another by any of their characteristics, i.e. screw pitch, thread shape, screw head design or shape, tip, the presence of non-threaded parts, etc.

Different screws are known that are partially hollow, with the presence of a bore, for example, passing through the screw laterally, or that are hollow, as in the present invention, in the sense that the screw thread is constructed on a hollow cylinder that supports the screw head. Said screws are constructed from a single piece that is punched, in the same way that a nut would be formed, creating the internal passage of the screw.

The reasons for using hollow screws include having available, on occasion, inside threads or inside shapes that allow the coupling of a certain component that is connected thereto. Furthermore, certain screws are known that are formed by two parts that, when joined together, form the screw as a whole. This is the case of the security screw of the Spanish patent with publication number ES2308937, in which the screw is divided into two parts via its axial axis and wherein, with a sector of thread omitted, the screwing or unscrewing of said screw is possible, in accordance with the relative positions of said parts . The principal object of the present invention is to construct a hollow screw, with the consequent reduction in the weight thereof, which is formed from two halves which, when joined, constitute said screw. A further principal inventive object of the present invention is to allow the production of said type of screws from sheet metal pieces , metal sheets or metal strips of adequate thickness. These and other advantages of the present invention will become more apparent in the course of the following description thereof.

BRIEF DESCRIPTION OF THE INVENTION

The present invention relates to a composite screw formed by two laminar halves that are joined together in order to form same, such that said screw is hollow. Said halves are connected by means of a mechanical join that, for example, connects the tip of the screw or, in other embodiments, the lateral part of the screw. The two halves fit together simply by juxtaposition, the nut that will be screwed onto the screw being that which will likewise prevent mutual detachment of the two halves .

The invention relates to the production of connection shapes in certain zones where there is contact between the parts of the screw. One of the principal advantages of the invention, in addition to the aforesaid reduction in material and in the weight of the screw, the latter being hollow, is that deriving from the modular manufacturing process permitted by the invention. As the screw is formed by two symmetrical parts, manufacture thereof is reduced to a single stamping process, thereby simplifying the process overall .

All the aforesaid inventive objectives have thus been achieved, with the provision of a lightweight, hollow screw formed by a composition of two halves connected together .

BRIEF EXPLANATION OF THE DRAWINGS

For the purposes of a better understanding of the invention, the latter is accompanied by two sheets of drawings provided solely by way of illustration and not with a view to limiting the invention. Figure 1 is a perspective representation of one of the preferred embodiments of the present invention. Figure 2 is a lateral perspective view of the embodiment shown in the preceding figure.

Figure 3 is a perspective representation of a further possible embodiment of the invention, in which the head of the screw has a hexagonal shape and has no connecting part closing the parts at the tip of the screw, having, rather, a connecting part in the lateral parts or at the head of the screw, which are not shown by the figure.

Figure 4 is a further perspective view of the embodiment of figures 1 and 2.

Figure 5 is a cross section through a portion of the screw of figure 4.

Figure 6 is a plan view of the screw shown in the embodiment of the preceding figure. Figures 7 and 8 are each front views of the screw of the preceding figure, with the parts thereof open, showing the connecting element thereof.

DETAILED EXPLANATION OF THE PRESENT INVENTION

The present invention consists in a composite screw formed by at least two laminar parts that are juxtaposed, connecting the zones of contact (6) thereof, and which are held together by a connecting means . This screw is hollow but may have any configuration amongst those possible in terms of the shape of the head, interior surface, thread and type of outside thread, inside thread or lack thereof, shape of the shank and of the tip, etc.

This screw is preferably metallic, made from steel, but any material suitable to the function thereof may be used, for example plastic resins of adequate hardness, etc .

In the embodiment shown principally in the drawings , the tip of the screw incorporates a means for joining the parts thereof which has the form of a connecting part (3) . Figures 7 and 8 show a detail of said join. The ends of the halves of the screw, the tip thereof, have a recess between abutting parts (5) via which run the end faces (4) of the connecting part (3) . When the two threaded parts (1) of the screw are placed against one another, juxtaposed, the connecting part (3) forces the tips thereof to be held closely joined, as it constitutes a physical limit on the separation thereof.

In accordance with each type of embodiment, the invention makes provision for the line of contact (6) between the two halves that form the screw to optionally incorporate a certain engagement shape, for example a zigzag in the head part (2) thereof. This could make it more difficult for there to be relative movement between the parts .

In another possible embodiment, a means for connecting the parts of the screw may be included, located in another location thereof, other than the tip thereof, for example in the head (2) or in the lateral part or thread (1) of the screw.

This is the case of the representation in figure 3, in which the screw does not have said connecting part at the tip thereof and may incorporate, if required, a connecting part that is similar but adapted to suit the lateral arrangement thereof or the arrangement thereof in the head (2) of the screw. Said figure does not show said connecting part, which is an optional element. For example, the nut that will be screwed onto the outside thread (1) of the screw may be sufficient to secure the connection of the parts thereof and to prevent the detachment thereof .

The invention has been illustrated by means of a connecting part as joining means, although this may be achieved by other connecting means of the staple or clip type, for example, without this representing a substantial variation in the invention.

Preferably, the invention is produced in a process of progressive stamping thereof, although other manufacturing processes, such as laser cutting, hydroforming, etc., are possible.

A further important advantage obtained with a screw according to the present invention is that functioning thereof is ensured since it is an element with elastic reserve, reacting favorably to vibrations and, for example, preventing the screw from becoming loose simply as a consequence of said vibrations . The screw is light in weight, because it is hollow, simple to manufacture and economical in terms of cost, allowing different variants of thread, pitch, shape thereof or shape of the head thereof, etc., always in keeping with the essence of the present invention.

It will be understood that in the present case the details relating to finish and form of the invention are subject to variation insofar as the invention is not changed beyond the scope thereof defined in the essential claim and the claims accessory thereto.