The present process is suitable for use in the sector of door and window frames, and in particular the area related to the production of metallic or plastic grills fitted to them. Background Art

Metallic or plastic grills positioned between two glass sheets are in increasing use today in the sector of door and window frames. Their purpose is almost exclusively aesthetic, as opposed to former times when they were employed in the construction of stained glass windows (using lead) or for protection against theft. Aluminium and light alloys are generally preferred today, though they are unable to guarantee complete protection against the break-in of intruders. However, the lightness of these materials allows grills of modest weight to be constructed, which therefore do not weigh down the frames. The same also holds true for grills made in PNC or other plastic materials.

They may be fixed onto windows or doors, even where there is no glass compartment. The grills can additionally be used in all sectors of fixtures and fittings: furniture, mirrors, surfaces of room dividers, etc. The grills are made up of tubular elements, put together

into a solid construction through construction through in¬ ternal and external forked connections at the junctions. These junctions are made up of arms at all possible angles, but the preferred forms are the right-angled cross, "X", "T'V "L", "Y", and curved.

In this way, square, triangular, circular, and other geometrical shapes of varying degree of regularity can be built up, although without doubt the right-angled variety is most common. More recently, union of the separate parts of the junctions has been carried out using a metal or plastic bar inserted across through openings made in one of the pieces, its free ends inserted into two other pieces, so that it also functions as a support for the structure. The tubular elements employed have various profiles, though the form preferred by the market is a somewhat compressed hexagonal shape; this form is easier for introduction between the two glass sheets and in any case ensures minimum bulkiness on the windows and doors or fixtures and fittings. For this reason, bar or rod elements are sometimes used in grills, with very modest cross-section.

One of the main problems associated with the grills is that many pieces of the tubular elements (or rods or bars) are needed in the construction.

The manufacture of these elements is today rather costly because in order to provide for their perfect matching at the junctions, the elements themselves have first to be cut orthogonally and then a subsequent milling of the ends is applied until the various tube profiles meet perfectly together without leaving ugly gaps. Where the elements are joined using internal bars, it is essential to put in a series of holes (later milled), to allow insertion of the bars themselves. Each of these operations in itself may be fairly low in cost, but they are repeated such a high number of times that production of the grill itself is a very expensive process. Just to give an example,- it is sufficient to consider a simple grill made up of three vertical, and three horizontal elements, comprising fifteen pieces, needing fifteen orthogonal cuts, eighteen milling operations of the ends to be inserted, nine holes for inserting the bars used in the junctions, and the same number of millings of these holes. As far as technical skills today go, there is no alternative way of producing profiled tubular elements for the joints needed for making up plastic or metallic grills. Disclosure of Invention The purpose of this invention is to make available a process able to allow manufacture of pieces of tubular

elements profiled in a suitable way for the construction of grills at a very modest cost, using simple methodologies and low operating costs.

Another aim is to allow production of pieces perfectly profiled for insertion into the junctions, more quickly than using current methods.

A final aim of this process is to work a number of pieces together.

These and other goals are brought together in the processing through punching of the tubular elements, as described herein, process that includes the cutting of the profiled pieces and their subsequent punching, such as to allow in just two simple operations the production of pieces already profiled for inserting into the junction; a second punching then allows production of the necessary openings for inserting the bars or other pieces that form the junction.

This procedure of working can be applied in the production of pieces with a junction that is either orthogonal (cross, "T" , "L", etc.) or angled at various degrees ("X", "Y", curved, etc.).

The advantage is thus gained of avoiding the operation of milling the piece ends.

Brief Description of Drawings Further features and advantages of the working method

can be seen better from a description of one of the preferred though not exclusive forms of carrying out the production of the piece, seen in the attached diagrams that give just one illustrative idea, where: - figure 1 shows a grill inserted within a glass compartment; figure 2 gives greater detail of the axonometry of a junction where the tubular pieces are pulled out and the internal bar within the junction can be seen; - figure 3 shows in axonometry the junction from the previous figure, where the components have been brought together in a cross junction (at right angles); figure 4 shows a front elevation of the pieces being worked in the punching process and of three tubular pieces; figures 5, 6 and 7 - also show sections of the punching press, along planes A-A, B-B and C-C of figure 4, together with the separated parts of the different punchings; the dotted lines indicate the movement of the various punches.

Mode for Carrying Out the Invention

For producing the three tubular elements (1.1 and 1.2) needed in each junction 2 of a grill 3 with cross-fitting (figures 2 and 3), the process involves a sequence of four operations: a) orthogonal cutting of all the tubular

elements, b) partial punching of the ends of the elements 1.1, c) full punching of these ends, d) lateral punching of the remaining tubular element 1.2. Tubular elements 1.1 will make up the horizontal pieces of junction 2, while element 1.2 is the vertical element (for the mounting).

In more detail, elements 1 are first cut orthogonal, to the required lengths, and then inserted into a pneumatic punching press. This executes a punching of the ends that are to fit into the junction of each tubular element 1.1 , removing the corner 4 from the worked piece, as seen in figure 5. This is done using punch 5 that begins its movement from the interior of element 1.1 and works orthogonally to it. In this way, an almost perfect profiling of the half-end of the element 1.1 being worked is obtained. The third phase always occurs within the punching press: in the end of each tubular element 1.1 that was given a partial profiling during the previous operation, a second punching takes place, this time complete and acting on the whole profile, using punch 6.

This latter works orthogonally penetrating element 1.1 through the opening left open by the removal of the mentioned corner, removes the second corner 7 from tubular element 1.1 and files down the whole of the

inside of the end of this latter, removing the shavings. This latter operation then allows production of tubular elements 1.1 with an outline perfectly profiled and ready for fitting straight into the junctions with tubular element 1.2 at junction 2 of grill 3.

The fourth and final phase always occurs within the same punching press. The element 1.2 that is to constitute one of the mounting pieces of the grill undergoes a punching operation for creating slot 9, using punch 10 that works across through the two parallel walls of element 1.2 itself, removing the surface pieces 11 , of sufficient dimension to allow the passage of joining bar 12.

The last three phases are worked simultaneously, though on three separate elements 1.1 and 1.2. The two tubular elements 1.1 and element 1.2 are then taken out from the punching press. A new element 1.1 is positioned on the first matrix for removal of corner 4, an element 1.1 already partly profiled is transferred to the second matrix for the punching of its whole profile and the removal of the second corner 7; a new element 1.2 is placed on the third matrix, and so on. All that remains at this point is to mount the grill 3. This is done by feeding bar 12 orthogonally through slot 9 of the tubular profile, such that its ends remain free; tubular elements 1.1 are then fitted onto these ends so

forming the crossed junction 2.

In the example given above, a simple grill with three vertical and three horizontal components, made up of a total of fifteen pieces, requires a total of fifteen orthogonal cuts, eighteen partial punchings of the ends and nine for making the slots 9 for insertion of the bars 12 that are used to form the junction, giving a total of forty five punchings. The total number of mechanical operations carried out is therefore greater than that in a traditional system but the speed is considerably higher for two reasons: higher speed of punching compared with milling and the simultaneous working of three different types of punching, that produce in a single operation one finished element 1.1 and one finished element 1.2.

The process of working, carried out in this way, can be modified or varied in many ways, all in line with the intentions of the original invention. In addition, all aspects may be replaced by others that are technically equivalent.

Of these variations, the most important point is that the profiling itself of the tubular elements 1.1 that make up the horizontal pieces of junction 2 can be accomplished in one single punching.