DESCRIPTION

"Fitting"

[0001] The present invention relates to the fittings sector, in particular for compressed air.

[0002] As is known compressed air fittings are currently made from brass or technopolymer .

[0003] In brass fittings the cost of the raw material greatly influences the final cost of the product . It has been estimated that the raw material affects the final cost of a fitting by a percentage of 35% to 60%, depending on the type of fitting. The only way of recuperating costs in this sector is by changing ^' the raw materials used and the technological production process, which is strictly linked to the type of raw material chosen.

[0004] One disadvantage of brass fittings is related to the fact that such fittings must obligatorily be treated after their production to prevent the release of lead.

[0005] Technopolymer fittings suffer rather from a number of technical limitations in particular applications. For example, over 70 °C the technopolymer goes into crisis and its mechanical characteristics lapse. Other critical applications for technopolymer fittings are environments where alcohol vapours are present (highly corrosive environments), or with exposure to solar rays. In these and other cases a fitting made entirely of brass needs to be used.

[0006] The purpose of the present invention is to propose a fitting which has the same mechanical and application characteristics as a brass fitting (resistance to temperatures, corrosion, light etc) , and which is able to offer further advantages and benefits, such as being lead-free and having a lower production cost compared to brass fittings.

[0007] Such purpose is achieved by a fitting according to claim 1. The" dependent claims describe preferred or advantageous embodiments of the fitting.

[0008] The features and advantages of the fitting according to the invention will, in any case, be evident from the description given below of its preferred embodiments, made by way of a non-limiting example with reference to the appended drawings, wherein:

[0009] - Figures 1, la and lb show in a perspective view, elevated view and end view, an example of a fitting body according to the invention;

[0010] - Figure 2 is a cross-section of the fitting body along the line A-A in figure lb, as shown after extraction from the mould;

[0011] Figure 3 is a cross-section of the complete fitting connected to two tubes; [0012] - Figures 4-6 show, in cross-section, other examples of fitting bodies according to the invention, and

[0013] -Figure 7 shows, in cross-section, an example of a die casting mould for making a fitting according to the invention.

[0014] The fitting according to the invention comprises a fitting body 10, made entirely in aluminium. Said fitting body comprises at least one input portion 12 suitable for receiving a tube 2.

[0015] Blocking means 14 act in conjunction with said input portion 12 to block the end of a tube 2 in said input portion 12. Said input portion 12 is a cone shape tapering towards the input aperture 12' of the tube, the taper of said input portion 12 being between 4° and 12°, preferably between 6° and 10°.

[0016] As can be seen for example in figure 3, such taper makes it possible to make a fitting body in aluminium by moulding which, at the input aperture of the tube 12' has a diameter substantially equal to the diameter of the front flange 14' of the blocking means 14, suitable to be pressed by the operator to permit the extraction of the tube 2. For example, the thickness of the fitting body at said input aperture 12' is just 0.9 mm. This permits the operator to act only on the front flange 14' without being obstructed in gripping by the end of the fitting body delimiting the input aperture 12'.

[0017] The angle chosen further permits the possibility of moulding twelve or sixteen impressions, depending on the figure, simultaneously and without jeopardising the final quality of the moulded fittings.

[0018] In one embodiment, the inner figure of each portion of fitting 12 comprises a first portion 12a facing the input aperture 12 ' , suitable for receiving the blocking means 14, a second portion 12b, of a slightly smaller diameter than the first so as to define an annular abutment shoulder 12a ¹ , for the insertion of the blocking means 14, and a third, innermost portion, of a smaller diameter than the first two and substantially equal to the outer diameter of the tube 2. Said third portion 12c is suitable for receiving the tube end 2. The second portion 12 defines a seat for an annular sealing element 20 acting in conjunction with the outer surface of the tube 2.

[0019] The choice of aluminium as a material for making the fitting body is based on many reasons. This material has been widely used for years in the automation sector (the bodies of solenoid valves are made entirely from aluminium) the heads and liners of pneumatic actuators - so-called "cylinders"- are also made from aluminium) and it is therefore looked on kindly by end users. [0020] Currently aluminium material is present on the market in great quantities unlike copper (basic component of brass) . This would encourage the belief that the- reference price should vary within tolerable values and above all be linked to the economic trends in the sectors it is used in.

[0021] The specific weight of molten aluminium is 2.56-2.64 kg/dm3 while that of drawn brass is 8.43-8.73 kg/dm3. It is easy to see that for the same volume, the raw material used is more than 70% lower. Expressed in other terms, for the same quantity of raw material used to make a fitting in brass, 3.3 can be made in aluminium.

[0022] Currently the price per kilo of brass, taking the London Metal Exchange (LME) as reference, is approximately 4.65 euro per kilo, while aluminium costs 2.0 euro a kilo, practically half. So for the same cost of raw material if three fittings can be made in brass, twenty can be made in aluminium.

[0023] The technological manufacturing process with aluminium differs radically from that with brass. In fact, it permits use of die-casting technology with high quality aesthetic results compared to those of turned brass.

[0024] No turning scrap is produced. Such scrap is closely connected to other processing costs which inevitably cause falls .in production and therefore costs which oscillate from 5% to 11% depending on the technological process used, for instance if hot moulding or turning of the piece.

[0025] Thanks to its low specific weight, and to the parity of mechanical characteristics with brass, aluminium appears an ideal product for robotics where .masses are of crucial importance for the speed of movement of the robots .

[0026] Thanks to the use of die-casting as the production technology of the aluminium fitting, the following advantages are achieved:

[0027] -possibility of making even complex shapes of reduced thickness;

[0028] - highly repeatable production;

[0029] -excellent duration and mechanical resistance of the die-cast product;

[0030] -ample aesthetic finish possibilities;

[0031] The outer geometric shape of the fitting according to the invention has been designed so that the final thicknesses of the piece equal the mechanical resistance of articles in brass; in particular, the fitting must be able to withstand the pressure of the inner components which is exerted once air is inserted in the tube.

[0032] The taper used, depending on the type of figure, may vary from a minimum of 4° to a maximum of about 12°, preferably 6° to 10°.

[0033] Figure 7 ^" shows an example of equipment 30 for obtaining the fittings according to the invention by moulding.

[0034] The equipment - 30 comprises a die 40, formed of a fixed part 42 and a moveable part 44. Said parts of the die 40 form, when placed alongside, a plurality of moulding ^' cavities 46 suitable for receiving the aluminium in a molten state to make the body of the fitting. In particular, in one embodiment, each moulding cavity 46 communicates with the outside through a first passage 48, formed by placing the two parts of the die alongside, and a second passage 50, orthogonal to the first, made in the moveable part 44 of the die 40. The first passage is suitable for receiving a pin 52 for making the inner figure of a first input portion of the fitting. The second passage 50 is suitable for receiving a telescope- pin 54 which performs a dual function: said telescope- pin 54 permits the inner figure of a second input portion of the fitting to be made moreover, said telescope-pin 54 is fitted with an axial through hole which an extractor 56 is housed in with the possibility of axial sliding. For example, said extractor 56 is supported by an extraction table 58 in such a way that the telescope-pin 54 can be moved independently of the extractor 56.

[0035] The moulding process then takes place according to the following steps:

[0036] closing of the die 40;

[0037] insertion of the pin 52 and the telescope-pin 54 in the respective passages;

[0038] injection of the molten aluminium in the moulding cavities 46;

[0039] opening of the moveable part 44 of the die;

[0040] extraction by means of moving the table 58;

[0041] expulsion of the piece by the extractor 56.

[0042] As a result, the telescope-pin 54 being integral with the moveable part 44 of the die, when the latter moves away from the fixed part 42 together with the moulded piece, it slides in relation to the extractor 56, which then causes the expulsion of the piece.

[0043] The extraction system of the pieces from the die described above, combined with the tapered shape of the fitting, means a large number of impressions, for instance twelve, can be obtained.

[0044] In addition, thanks to the fact that the extractor 56 acts inside the moulded piece, one advantage of this production process is the total elimination of extraction marks on the outer surface of the pieces.

[0045] After the extraction of the fitting bodies 10 from the die, such bodies are then taken back to make the inner passages which place the input portions 12 of the tubes in communication with each other or at least with a connection attachment 15 to another device.

[0046] The cross-section in figure 4 shows an example of a fitting body 10 after it has been taken back to make the passage which connects an input portion 12 for a tube to an attachment 15.

[0047] A comparison of the production cycle of a brass fitting and the production cycle of an. aluminium fitting will now be presented.

[0048 Brass

[0049 Cycle time: 7" (per piece)

[0050 Moulded weight: 28 g.

[0051 Weight of finished article: 8.60 g.

[0052 Turning recovery: 20.95 g.

[0053 Pieces obtained 1

[0054 Aluminium

[0055 Cycle time: 40" (per run)

[0056 Cycle time: 40/12 = 3.33" (per piece)

[0057 Moulded weight: 7 g.

[0058 Weight of finished article: 6 g.

[0059 Turning recovery: 1 g.

[0060 Pieces obtained 12 (per run)

[0061 This process for making an aluminium fitting therefore permits various advantages compared to the production of fittings in brass: a saving of resources, energy saving during production, lower lead content in the product, lower weight and consequent reduction of consumption for packaging and transport. Moreover, there is a considerable reduction in the production costs of each single figure.

[0062] More in detail, as regards the saving of resources, it should be noted that the fittings according to the invention can be made from secondary aluminium (recycled metals) with a final improvement treatment of the alloy. The articles in brass rather are produced using a primary alloy. The non-ferrous metals industry and in particular that of aluminium is one of the sectors in which the benefits of recycling are maximised. In 2004 about 16.4 million tons of bauxite were preserved as a result of aluminium recycling activities in western Europe. Given that it is an alloy, aluminium contains one or more alloy materials to improve its characteristics of strength and resistance. The recycling of aluminium therefore also contributes to the sustainable use of resources such as silicon, copper, iron, magnesium, manganese, zinc and other elements. A study (EAA, 2000) of the use of recycled aluminium has shown that the production of one ton of recycled aluminium can lead to a saving of: [0063] 1,300 kg. of bauxite residues

[0064] 15, 000 litres of cooling water

[0065] 860 litres of process water

[0066] 2, 000 kg of C02

[0067] 11 kg of S02

[0068] The AEA Technology (2001) study estimates that from 1 ton of recycled aluminium, 0.93 tons of aluminium laminate are made .

[0069] As regards energy saving, it is to be .noted that aluminium is a huge energy bank because the production of aluminium from raw materials requires a huge energy input. Waste and recycled aluminium therefore have a great intrinsic value on account of the energy stored in the material used to produce them.

[0070] According to the "Life Cycle Inventory of the Worldwide Aluminium Industry with regard to Energy Consumption and Emissions of Greenhouse Gases" report (IAI, 2000), the production of aluminium from scrap requires only 5% of the energy (and generates only 5% of the climate altering emissions) used to produce aluminium from raw materials. The energy needed to melt aluminium scrap is merely a fraction of that needed for the production of primary aluminium.

[0071] According to EPA (Environmental Protection Agency of the United States) , the recycling of aluminium cans can save from 60% .to 74% of the energy needed to produce them from raw material. Moreover since the atomic structure of the aluminium is not altered during the manufacturing process, the aluminium can be recycled for an indefinite number of times using only 5% of the energy needed to produce primary aluminium. This permits lower environmental impact, unlike brass.

[0072] As regards the environmental aspects, the following considerations may be made.

[0073] The brass industry recovers about 600, 000 tons of zinc per year. The processing of secondary zinc produces the emission of pollutants in environmental areas. The emission in the air is formed of fumes of zinc, other volatile metals, melting fumes and products generated by the incomplete combustion of other organic and inorganic components (grease, rubber, scrap plastic .etc) . Brass, once processed, requires a galvanic treatment (nickel or chrome) . If moulded, it requires a further "cleaning" process suitable for preparing the piece as regards the surface. These processes create problem areas affecting both the environment and the health and safety of workers .

[0074] The recycling of aluminium is necessary and sensible; in fact not only does it entail advantages for consumers, local authorities and. industry, the reduction of bauxite mining is also a valuable contribution to safeguarding the environment. The aluminium fitting, once moulded, is treated with electrolytic tinning. The tinning treatment is appreciated most in the electronic and electromechanical sectors given its qualities of electric conductivity and its suitability for soldering. It is also widely used in the food industry thanks to its anodic behaviour compared to iron in such applications.

[0075] Lastly, as regards packaging and transport, aluminium is light and resistant to impact: its high resistance: weight ratio ensures maximum protection from accidental impact during transport, adding a minimal weight to that of the packaged product. This reduces the costs of packaging and transport.

[0076] A person skilled in the art may make modifications and variations to the embodiments of the fitting and its moulding method according to the invention, replacing elements with others functionally equivalent so as to satisfy contingent requirements while remaining within the sphere of protection of the following claims. Each of the characteristics described as belonging to a possible embodiment may be realised independently of the other -embodiments described.