Method of manufacturing hinge devices and hinge devices obtained thereby

This invention relates to a method of manufacturing hinge devices, and hinge devices obtained thereby.

Known are hinges, the male element of which is internally hollow and sealed, to lighten the structure while lowering production costs.

Such a product and the method for obtaining it are claimed in the European Patent application N. 86100126.1 filed on January 7, 1986 by the same Applicant.

That known type has, however, some small drawbacks: first of all, at the upturned and plugged bearing end of the hollow pin, there occurs gradual fatigue of the material, which tends to become further compressed and consequently depressed, which results in the female element of the hinge bearing on the annular base of the male element, thus worsening its operation owing to the increased frictional contact between the elements and the formation of oxides.

In the instance, moreover, where it was desired to impart to the male element a particular decorative shape, it was possible to form during the second extrusion step a tang, to be later machined as required.

However, also in this case, there is a drawback due to the cost of the additional material involved in providing a tang for further machining.

The primary aim of this invention is, therefore, to eliminate the above drawbacks affecting known types, by providing a hinge device having reduced overall cost and in particular reduced material consumption in combination with sealed features, possibly also having the male and female ends suitably machined.

A further important object is to provide a method which affords a sealed hinge device without implying the addition of sealing bodies of a different material.

Another important object is to provide a hinge device having a strong and homogeneous pivot point.

A not'least object is to provide a fully automatic method which can be implemented using ordinary plant and equipment.

These and other objects are achieved, according to one aspect of the invention, by a method of obtaining a hinge device comprising male and female hinge elements with a hollow body, which is characterised in that it comprises the following process steps:

• a) shearing a cylindrical drawn segment;
• b) cold impact extruding said cylindrical segment by means of a punch adapted to cause the material to flow laterally up to provide a constant pattern hollow body having at least one open end, on the other end there being formed instead a pin and an open cavity of a lesser size;
• c) upsetting in succession a portion of said hollow body from the open end by impact from a die defining an undulated conformation;
• d) blocking the previously upset open end by upsetting;
• e) surface finishing the hinge elements thus formed.

According to another aspect of the invention there is provided a hinge device which is characterised in that it comprises a male element having a pin and an inner cavity the end of which is shaped and blocked., said hinge further including a female element also having an inner cavity the end of which is riveted and a seat for the pin, a means being provided for associating the hinge with casings.

Further, features and advantages of the invention will be more clearly apparent from the detailed description of a particular but not exclusive embodiment, shown by way of illustration and not of limitation in the accompanying drawings, where:

• figure 1 shows the cylindrical drawn segment;
• Figures 2,3 and 4 show a view taken on a longitudinal section plane of the male element of the hinge device depicted during some steps of the process;
• Figures 5 and 6 depict, in a similar view to the preceding ones, the female element during the steps of the process; and
• Figure 7 is a part-sectional view of the hinge device.

With reference to the previously mentioned figures, the method comprises a first step of shearing a cylindrical drawn segment, defining a stock, formed from a wire (not shown). The material volume making up the stock shall have to be equal, of course, to the volume of the semifinished product obtained with the last step. That stock is upset by striking on a mould in order to obtain a regular cylinder 1 having an end 2 provided with a flat surface 3 and a rounded area 4 at the other end. In a following step the cylinder 1 is cold extruded in a mould by means of a cylindrical punch having a smaller cross-section than the surface 3; thus, the material is displaced laterally to define a cylindrical body 5 having an inner cavity 6 of the same shape; said cavity 6 is blocked at one end, the other, denoted by the numeral 2, having an opening 7.

Depending on whether the method is utilised to make male 8 or femal 9 elements, in this step the remote end 10 from the end 2 of the body 5 will present, respectively, a cylindrical element 11 projecting perpendicularly along the longitudinal mid-axis from a flat annular base 12, defining the pin and a second cavity 13, of a lesser size than the cavity 6 of essentially cylindrical shape, formed on a flat base 14 at the longitudinal mid-axis of the body 5, defining the seat for the pin itself.

The next step of the method provides for either cold or hot upsetting, of both the male 8 and female 9 elements, by successive strikes on the terminating end 15 of the body 5 having the opening 7.

In Figure 3 there is shown an intermediate step where there occurs a first shaping of the walls 16 of the terminating end 15. The end step, illustrated in Figures 4 and 6, defines an end 17 of essentially undulated shape with a spherical ornamental element 18 at the end which blocks the cavity 6 of the body 5.

The blocked end 17 thus closed also prevents liquid from entering during the following step of immersion into galvanic baths for the necessary treatment. The cavity 13 of the female element 9 is shaped conformingly with the pin of the male element 8, its depth being preferably slightly less than the length of the pin itself in order to have the hinge work and bear on the end of the same and not on the annular base 13, thereby improving the hinge's functional aspect since friction is reduced and the pivot point is protected, within the female element 9 against any outside atmospheric agents.

With each of the side surfaces 19 and 20 of the body 5 there is expediently rigidly associated a means 21 adapted for associating the elements 8 and 9 forming the hinge with items to be hingedly connected together such as casings, said means being advantageously comprised of an externally threaded shank.

By virtue of the fact that the male 8 and female 9 elements are hollow, production costs are lowered by decreasing the quantity of raw material used.

Upturning and shaping the end 15 in addition to impart a given appearance to the hinge closes the cavity 6, thereby preventing the liquid present in the successive galvanic baths from entering the hollow elements 8 and 9, without the additional provision of sealing bodies.

Thus it has been shown that the method of forming male and female hinge parts with a hollow body and the thus obtained hinge device achieves all the objects set forth, affording lower costs and concurrently improving the hinge's functional aspect. Of course, the invention herein is susceptible to many modifications and changes within the scope of this same inventive concept.

Thus, as an example, during the cold extrusion by impact of the cylinder 1, a solid pin may be formed or one having a partial inner cavity in communication with that of the body. Of course, also the materials used, the dimensions of the hinge and the aesthetic conformation conferred on the end of the same may be any ones contingent on requirements.