WO2003076684A1

WO2003076684A1 - System for vacuum metallization of objects treated in batches

Info

Publication number: WO2003076684A1
Application number: PCT/IT2003/000131
Authority: WO
Inventors: Mario Ceni; Stefano Fanfani
Original assignee: Galileo Vacuum System S.R.L.
Priority date: 2002-03-08
Filing date: 2003-03-04
Publication date: 2003-09-18
Also published as: AU2003217463A1; ITFI20020042A1; EP1485517A1

Abstract

The system comprises: a vacuum chamber, at least one carousel (23) rotating around an axis or rotation (A-A), which is positioned inside said vacuum chamber when the system is operating; associated with said at least one carousel, a first flexible element (61) closed in loop and connected to said vacuum chamber, driven around a first series of driving wheels (25,25A,25B) supported by said carousel (23): associated with said at least one carousel, a second flexible element (63) closed in a loop and connected to said vacuum chamber, driven around a second series of driving wheels (27,27A,27B) supported by said carousel; associated with each wheel of said first and said second series, respective seats for engaging corresponding rods (75) to support workpiece-holders (81,81A,81B,83,83A,83B) for said objects, with torsional coupling means (37,47,57) between each rod and the respective driving wheel.

Description

SYSTEM FOR VACUUM METALLIZATION OF OBJECTS TREATED IN BATCHES

DESCRIPTION Technical Field The present invention relates to a system for vacuum metallization and more particularly to a system for vacuum metallization of objects treated in batches, that is to say provided with a vacuum chamber in which the workpieces to be metallized are introduced, placed on and/or fixed to specific workpiece-holders to then be subjected to metallization. Subsequent to metallization the vacuum chamber is opened to remove the metallized workpieces and replace them with others to be treated. State of the Art

Currently, existing systems for vacuum metallization of objects in batches comprise a vacuum chamber provided with a carousel carrying a series of rods to which planetary movement is imparted via a flexible element fixed to the vacuum chamber. Workpiece-holders on which the objects to be metallized are placed and fixed are connected to the rods. These workpiece- holders have various shapes and dimensions and are positioned so as to make maximum use of the space available inside the vacuum chamber, which is usually cylindrical in shape.

The layout of workpiece-holders and their overall dimensions in systems cannot be varied easily as a function of the type and the dimensions of the objects to be metallized, with the consequence that the space available inside the vacuum chamber is not always optimized. Optimization of the space is however an important aspect, as it has a high incidence on production costs, as optimal use of the space available makes it possible to increase the production of each treatment cycle and therefore, as a result, the average hourly production of the system.

In these systems - after having performed metallization through the vaporization of small metal bars (for example aluminium) placed in the vacuum chamber - the objects are covered with a polymer film obtained by introducing suitable products which are blown inside the vacuum chamber and deposit on the surface of the metallized objects, inducing polymerization and cross-linking. In some cases a similar treatment is also performed before metallization. In order to introduce these products into the vacuum chamber, nozzles distributed in a varied manner inside the vacuum chamber are currently used, the dimension of which reduces the space available for the workpiece-holders on which the objects are placed, with consequent negative effects in terms of system productivity. Objects and summary of the invention

The object of the invention is to provide a system which overcomes the drawbacks of traditional systems and, in particular, makes it possible to rapidly modify the configuration of the workpiece-holder for the product to be metallized in order to optimize use of the space inside the vacuum chamber as a function of the conformation of the objects to be metallized.

The object of an improved embodiment of the invention is to obtain a system in which the means to introduce the products destined to form the protective film on the metallized objects or objects to be metallized do not reduce the space available to position the objects to be metallized in the vacuum chamber.

According to a first aspect, the present invention therefore provides a system comprising:

• a vacuum chamber;

• at least one carousel rotating around an axis of rotation, which is provided inside said vacuum chamber when the system is operating;

• associated with said at least one carousel, a first flexible element closed in a loop and connected to said vacuum chamber, driven around a first series of driving wheels supported by said carousel;

• associated with said at least one carousel, a second flexible element closed in a loop and connected to said vacuum chamber, driven around a second series of driving wheels supported by said carousel; • associated to each wheel of said first and of said second series, respective seats for engaging corresponding rods to support workpiece-holders for said objects, with torsional coupling means between each rod and the respective driving wheel.

With a device of this type it is therefore possible, with a rapid and easy maneuver, to insert supporting rods in the first series or in the second series of seats. The rods that are inserted in the first series of seats are equipped with workpiece-holders with a specific radial dimension, while the rods destined to engage in the second series of seats are equipped with workpiece-holders with a different radial dimension. The radial dimension is constituted by the cylindrical volume inside which the workpiece-holders move when they are made to rotate during the planetary movement imparted by the flexible elements.

It is thus possible, by inserting rods in the first series of seats only, to position workpiece-holders inside the vacuum chamber which have, for example, a larger radial dimension. Vice versa, by inserting the rods in the second series of seats only, workpiece-holders of a different diameter are positioned inside the vacuum chamber. A mixed configuration is also possible, in which rods are inserted in some of the seats of the first series and in some of the seats of the second series, so that workpiece-holders of two different dimensions are available inside the vacuum chamber. This may be advantageous when it is necessary to treat in the same batch objects with shapes and dimensions that vary greatly from one another.

Further advantageous characteristics and embodiments of the system according to the invention are indicated in the attached dependent claims and shall be described in detail with reference to a non-limiting embodiment illustrated in the attached drawings. The inventive concept identified above may be implemented both in systems in which the carousel rotates around a vertical axis and in systems in which the carousel rotates around a horizontal axis. The example described below illustrates a system with vertical axis, with a vacuum chamber that is formed by a body and a closing port, although it must be understood that this is merely one possible configuration. Systems with horizontal axis are usually equipped with a bell jar or vacuum chamber which extends substantially cylindrically, with a horizontal axis, into which a carriage carrying the carousel is inserted and which moves in a direction parallel to the axis of the vacuum chamber and to the axis of rotation of the carousel.

According to a further aspect of the present invention, when using a system with vertical axis, with a vacuum chamber composed of a fixed body and of at least one closing port, at least one diffuser is provided next to the seal between the fixed part of the vacuum chamber and the closing port, preferably tubular in shape and extending parallel to the seal, to distribute, in the vacuum chamber, a product suitable to form the protective coating of the metallized objects. The diffuser - which will advantageously be equipped with gauged holes of variable diameter to compensate the drop in pressure inside it - is thus positioned in an area of the vacuum chamber in which it does not interfere with the dimension of the rotating carousel and the workpiece- holders. This makes it possible to optimize the use of the inner volume of the vacuum chamber. The diffuser may be one only and extend for the required length, or two or more diffusers may be provided, if necessary each provided with a single diffusion hole. Further characteristics relative to the shape and layout of this diffuser are indicated in the attached dependent claims and shall be described in greater detail with reference to the attached drawings, illustrating an advantageous and non-limiting embodiment of the invention. It will be understood that the diffuser with its characteristics may also be used, for the same objects and with the same advantages, in a system in which the carousel and relative workpiece-holders are produced using prior art, that is without it being possible to modify the configuration of the workpiece-holder as a function of the characteristics of the objects to be treated.

Brief Description of the Drawings

The invention shall now be better understood by following the description and attached drawing, which shows a non-limiting practical embodiment of the invention. More specifically, in the drawing: Fig.1 shows a front view of a system comprising a carousel produced according to the invention, equipped with a vacuum chamber composed of a fixed body which is closed alternately with one or other of two closing ports hinged to opposite sides of the fixed body;

Fig.2 shows the plan view according to ll-ll in Figure 1 ; Fig.3 shows an enlarged front view of one of the closing ports, according to the line Ill-Ill in figure 2; Fig.4 shows a sectional view according to IV-IV in Fig.3;

Figs.5, 6 and 7 show local sectional views according to V-V, VI-VI, VII-VII in Fig. 4;

Fig.8 shows, in a front view according to VIII-VIII in Fig. 4, the layout of the diffuser; Fig.9 shows a local sectional view according to IX-IX in Fig.8;

Fig.10 shows a similar sectional view to the sectional view in Fig. 4, according to X-X in Fig. 11 , of an improved embodiment of the carousel;

Figs.11 and 12 show front views according to XI-XI and XII-XII in Fig.10, in two different positions of the moving rod of the carousel; and Fig.13 shows a detail with a front view of one of the hinges to connect the closing port 11 B to the central fixed body 3, with a brake to lock the port. Detailed description of the Preferred Embodiment of the Invention

Figs. 1 and 2 show the general layout of a system for vacuum metallization of objects treated in batches, of the type with vertical axis, to which the present invention is applied. As mentioned, this is only one of the possible configurations of the system to which the invention may be applied.

Generally, the system, indicated as a whole with 1 , has a central body 3 which defines a portion of a cylindrical vacuum chamber with vertical axis. Two symmetrical closing ports, indicated with 11A and 11 B, are joined by hinges 9 to the two sides of the fixed central body 3.

In a per se known manner, the two ports 11A and 11 B are closed alternately against the body 3 to complete and close the vacuum chamber which is thus defined by the internal area of the fixed body 3 and alternately by the internal area of one or other of the two ports 11 A and 11 B. As can be seen in particular in Fig. 2, the plan development of the ports 11 A and 11 B is greater than the plan development of the central body 3, so that the geometric axis of the cylindrical vacuum chamber is located in the portion of the vacuum chamber formed by the closing port 11A or 11 B. This allows a carousel to be fitted inside both ports to support the workpiece- holders on which the workpieces to be metallized are fixed. This carousel shall be described in greater detail below with reference to the port 11 B, it being understood that the configuration of the port 11A is substantially symmetrical.

The configuration described above is per se known. As can be seen in particular in Figs. 3 and 4, a shaft 15 extends through the base or bottom of the port 11 B, the axis of which coincides with the geometric axis of the cylindrical vacuum chamber which is defined when the port 11 B is closed against the fixed body 3. Keyed onto the shaft 15 is a toothed pulley 17, driven on which is a toothed belt 19 which receives movement from a motor (not shown). Fixed to a flange 15A of the shaft 15 is a lower discoidal body or element 21, which constitutes an element of the carousel indicated as a whole with 23, housed partly inside the port 11B and rotatingly supported by the shaft 15. Therefore, the lower discoidal element 21 rotates, due to movement transmitted by the belt 19, around the geometric axis A-A of the vacuum chamber.

The discoidal element 21 supports a first series of driving wheels, which in the example shown are constituted by toothed wheels or pinions for chains, indicated with 25, 25A and 25B. More specifically, a total of eight toothed wheels 25A, 25B, 25 are provided positioned (in the example shown) at the vertices of a non-equilateral octagon. The wheels 25, 25A, 25B are located underneath the discoidal element 21. The discoidal element 21 also supports a second series of driving wheels, in this case also constituted by toothed wheels or pinions for chain, indicated with 27, 27 A, 27B. The second series of toothed wheels comprises six wheels 27, 27A, 27B positioned (in the example shown) at the vertices of a regular hexagon. The axes of the toothed wheels of the first series (wheels 25, 25A, 25B) are all, with the exception of the axis of the wheels 25A, 25B, outside the hexagon on which the axes of the second series of toothed wheels are located. The two wheels 25A, 25B fitted in diametrically opposite positions are coaxial to the wheels 27 A, 27B.

Assembly of the wheels 25 and 27 on the discoidal element 21 is shown in particular in Figs. 6 and 7. Fig. 6 shows the axial section of a driving wheel 25 of the first series. This wheel is supported, by interposing a free wheel mechanism 29, on a hollow shaft 31 in turn carried by bearings 33 inside a sleeve 35 connected integrally to the lower discoidal element 21. A transverse pin 37 is provided in the lower area of the hollow shaft 31 for purposes that will be explained below. The toothed wheel is fitted so that it can rotate freely in one direction around the axis of the hollow shaft 31 , while in the opposite direction it is torsionally connected to the shaft and therefore its rotation makes the shaft rotate.

Fig. 7 shows assembly of one of the driving toothed wheels 27. This is connected, by interposing a free wheel mechanism 39, to a hollow shaft 41 , in turn supported by bearings 43 in a sleeve 45 connected integrally to the lower discoidal element 21. The elements 39, 41 , 43 and 45 are substantially equivalent to the elements 29, 31 , 33 and 35 shown in Fig. 6, with the difference that the hollow shaft 41 is longer than the hollow shaft 31 and that positioned between the sleeve 45 and the toothed driving wheel 27 is an annular spacer 48 with greater axial extension than a corresponding annular spacer 38 provided on the hollow shaft 31.

Inside the hollow shaft 41 a transverse pin 47 is positioned, in relation to the discoidal element 21 , at the same height as the pin 37 inserted in the hollow shaft 31. It can be seen, therefore, in Figs. 6 and 7, that the toothed wheels 35 are on a plane lying at a greater height than the toothed wheel 27.

The wheels 25A and 27A and the wheels 25B and 27B are supported on a common axis. Their assembly is shown in the section of Fig. 5 with reference to the wheels 25A and 27A, the wheels 25B and 27B being assembled in a substantially identical manner. These two wheels are supported and torsionally coupled, with the interposition of a free wheel mechanism 50, to a hollow shaft 51 , in turn supported by bearings 53 in a sleeve 55 connected integrally with the lower discoidal element 21. The shaft 51 has a transverse pin 57 positioned at the same height as the transverse pins 37 and 47. The layout is substantially the same as that of the wheels 25 and 27. Fig. 5 again shows the different height at which the wheels 25A and 27A are positioned; this height corresponds to the one at which the wheels, 25 and 27 respectively, are positioned.

Therefore, the wheels 25, 25A and 25B lie on a horizontal plane parallel to the discoidal element 21 and underneath it at a greater height to the height of the plane on which the wheels 27, 27A and 27B are positioned. A first flexible element, in this example a chain, indicated with 61 , is driven on the toothed driving wheels 25, 25A, 25B. The flexible element 61 is connected by an arm 62 to the body of the port 11 B. A second flexible element 63 is driven around the toothed driving wheels 27, 27A, 27B and this too is connected by the arm 62 to the port 11. With this layout, when the lower discoidal element 21 is made to rotate by the pulley 17 and the belt 19, the hollow shafts 31 , 41 , and 51 will rotate around their respective axes indicated with B-B, C-C and D-D, due to rolling of the respective toothed driving wheels 25, 27, 25A, 27A, 25B, 27B on the flexible elements 61 and 63. The hollow shafts 31 , 41 , 51 are therefore provided with a planetary movement around the axis A-A of the vacuum chamber, said axis being carried by the port 11 B.

An upper annular element 71 is connected to the discoidal element 21 by means of uprights or columns 73, elements which complete the carousel 23. The upper annular element 71 is open in the centre to allow passage of the electrified bars, to which the vaporization sources, not shown and per se known, are connected.

Rods to support the workpiece-holders to which the workpieces or objects to be metallized are connected may be connected to the carousel composed of the lower discoidal 21 and upper annular elements 71 with the respective connection uprights 73.

As shown in particular in Fig. 3 the rods, indicated with 75, are inserted with their lower end in seats formed by the hollow shafts 31 , 41 and 51. In the configuration shown in this example, each rod 75 is also connected at the top to the inside of an annular seat 77 fixed to the upper annular element 71 , although this is not the only possible configuration, as will be explained below. Figs. 5, 6 and 7 show the lower ends of the respective rods 75 which are inserted in the seat defined by the respective hollow shaft 31 , 41 or 51. These lower ends of the rods 75 have a respective fork 75F which is used to torsionally connect the rod 75 to the hollow shaft 31 , 41 or 51 respectively by means of a pin 77 coaxial to the shaft 31 , 41 or 51 and inserted inside this. Each pin 77 has an upper tooth 77A which is inserted into the fork 75F of the rod and a slot or notch 77B inside which the transverse pin 37, 47 or 57 of the respective hollow shaft 31 , 41 or 51 is inserted. The pin 77 forms a spacer between the pin 37, 47 or 57 and the forked lower end portion 75F of the rod 75, to prevent the latter from penetrating too far inside the respective hollow shaft. Removal of the pin 77 makes alternative assembly of the rod possible, as described below. Each rod 75 is also provided with a stop collar 75B which cooperates with the front surface of the respective shaft 31 , 41 or 51.

Fixed to the rods, at variable heights, are the workpiece-holders of various shapes, not shown in detail and per se known, on which the objects to be metallized are placed and fixed. Only the overall dimensions of these workpiece-holders, i.e. the cylindrical volumes inside which they move during planetary movement around the axis A-A of the carousel, are shown as an indication and for clarity of the drawing in Figs. 1 and 3. The overall dimension of the workpiece-holders is shown in Fig. 4. Here the overall dimensions of the workpiece-holders fixed to the rods inserted coaxially to the driving wheel 25 are indicated with 81 , the overall dimensions of the workpiece-holders carried by the rods 75 coaxial to the toothed driving wheels 27 are indicated with 83 and represented by a broken line. Coaxially to the wheels 25A, 27A, 25B, 27B the overall dimensions 81 A, 83A, 81 B, 83B of the respective workpiece-holders are represented. The workpiece-holders to which the aforesaid overall dimensions correspond are indicated with 81 , 83, 81 A, 81 B, 83A, 83B below. As can be seen in Fig. 4, the overall dimensions of the workpiece- holders 81 , 81 A, 81 B is smaller than the workpiece-holders 83, 83A, 83B.

In actual fact, not all the rods that could be housed in the hollow shafts 31 , 41 , 51 , that is a total of twelve rods, will be fitted on the carousel 23, as this would cause interference between the workpiece-holders 81 , 81 A and 81 B and the workpiece-holders 83, 83A and 83B or between the workpiece-holders of one series and the rods of the other series. Typically, only the rods carrying the workpiece-holders 81 , 81 A and 81 B or, alternatively, only the rods carrying the workpiece-holders 83, 83A and 83B will be fitted. In other words, only the series of seats formed by the shafts 31 and 51 or by the shafts 41 and 51 will be occupied time by time. Operating in this manner, eight series of workpiece-holders 81 , 81 A, 81 B or six series of workpiece-holders 83, 83A, 83B will be available on the carousel 23. The dimension of the workpiece-holders and the distance and positioning of the axes of rotation, coinciding with the axes B-B, C-C and D-D are such that, using one or other of the two series of workpiece-holders, optimum use may be made of the volume available inside the vacuum chamber that is formed by positioning the port 11 B against the fixed body 3.

The layout makes it extremely easy to replace the rods bearing the workpiece-holders 81 , 81 A, 81 B with rods bearing workpiece-holders 83, 83A, 83B. In fact, the kinematic transmission which allows the rod 75 to move with a planetary movement around the axis A-A of the vacuum chamber does not require any modification when the rods are replaced. The two flexible elements 61 and 63 remain constantly in contact with their respective driving wheels 25, 25A, 25B, 27, 27A, 27B. The only operation required is removal of the rods from the seats formed by the hollow shafts 31 , 41 , 51 and their replacement.

It is clear from the above that workpiece-holders 81 together with workpiece-holders 83 may also be positioned inside the vacuum chamber, supported on the carousel 23, provided they are adequately distributed to prevent reciprocal interference. In other words, when objects of various shapes are to be metallized, it is possible to fit workpiece-holders with different radial dimensions on the carousel 23.

The method of fitting the rods 75 described above, with two end connections on each rod 75, prevents oscillating movements of the rods 75. In this way, the workpiece-holders 81 , 81 A, 81 B 83, 83A, 83B can have a diameter that leaves a minimum space between the workpiece-holders and the inner wall 11 C of the closing port 11 B.

When it is possible to obtain a greater distance between the ends of the workpiece-holders 81 , 81 A, 81 B, 83, 83A, 83B on one side and the inner wall 11 C of the port 11 B on the other it is possible to fit the rods 75 in a different and simpler manner. In this case, as slight shaking of the rods is accepted, they may be connected at the lower end only, meaning that it is no longer necessary to position the upper annular element 71 and relevant uprights to connect this to the lower discoidal element 21. In this case the rods 75 will be equipped with a stop 75B positioned at a greater distance in relation to the forked end 75F. The spacer pin 77 is omitted and the forked end 75F of each rod 75 will engage directly on the transverse pin 37, 47 or 57 of the respective hollow shaft 31 , 41 or 51. In this way the rod 75 is inserted for a greater length inside the seat formed by the hollow shaft 31 , 41 or 51 and does not require an upper support. This different system of assembly is used in particular when it is necessary to change the layout of the rods 75 frequently.

A diffuser nozzle is associated with the fixed body, to introduce a substance into the vacuum chamber to be deposited on the metallized objects and made to polymerize to form a protective film. This diffuser nozzle is omitted to simplify the drawing in Figs. 1 to 7 and is shown ih detail in Figs. 8 and 9.

The diffuser nozzle, generically indicated with 101 , is constituted by a tubular diffuser which extends from an upper end 103A to a lower end 103B. The upper end 103A is connected to a duct 105 to feed the product to be diffused inside the vacuum chamber, while the end 103B is closed. Gauged holes for product delivery are provided along the longitudinal extension of the tubular diffuser 103. The holes have a diameter gradually increasing from the end 103A to the end 103B to compensate the losses in load along the tubular diffuser.

The tubular diffuser 103 is provided with two brackets 105 with which it is clamped to the fixed body 3. As can be seen in particular in Fig. 9, the tubular diffuser 103 is fitted next to a seal 107 surrounding the entire opening of the fixed body 3 and which is fitted on a perimeter flange 3F of the body. The seal 107 is fixed on the flange 3F via pairs of strips 111 and 113. The tubular diffuser 103 extends parallel to the innermost strip 113 to hold the seal 107 in place. The strip 113 is fitted and clamped to the flange 3F by screws 115 which are also used to clamp the brackets 105, by means of an adjuster 117 which is clamped by the screws 115 together with the strip 113.

As can be seen in Figs. 8 and 9, with this layout the tubular diffuser 103 is positioned against the seals 107 in line with the perimeter flange 3F of the central body 3 and in fact does not take up space in the cylindrical volume of the vacuum chamber formed when the port 11 B (or 11 A) is closed against the fixed body 3 of the system. This layout makes the internal volume of the vacuum chamber fully available to the workpiece-holders and therefore maximizes the volume that can be used for metallization operations.

Figs. 10 to 12 show a variant of embodiment of the carousel which facilitates access to the central area of the port, in line with the axis of rotation A-A of the carousel, where the vaporization sources, not shown, are typically located.

For this purpose one of the rods 75 is connected to the carousel by a mechanism which makes it possible to draw the axis of the rod nearer or move it farther away to align it with the axis of the toothed wheel which makes the rod rotate, or alternatively to move it away from the axis of the carousel. In the example shown the rod is mounted on a system of articulated arms to carry the rod 75 and the relative workpiece-holders in an operating position (Fig. 12) or in a divaricated position (Fig. 10) which facilitates access to the central area.

In greater detail, as can be seen in Fig. 11 , the rod 75 in question is connected to the upper annular seat 77 and to the lower seat formed by the respective hollow shaft (in this case the shaft 51) not directly, but via two pairs of articulated arms indicated with 201 and 203 respectively. When the carousel is to be positioned in operating conditions, the two arms 201 are positioned so that they overlap each other, as are the lower articulated arms 203. In this position, the arms are appropriately clamped. The rod 75 carried by these arms is positioned according to Fig. 12 and rotates, together with the pairs of articulated arms and the workpiece-holders 81 B or 83B, around its own axis. When the carousel is not operating the rod supported by the arms 201 and 203 can be taken to the extracted position by divaricating the arms (Figs. 10 and 11 ) to allow access to the central area of the carousel.

In place of two pairs of articulated arms different mechanisms could be provided, designed to allow movement of the rod in relation to the axis of rotation, for example two pairs of upper and lower prismatic guides could be provided, each equipped with an orthogonal pin to connect them to the seats 51 and 77 and inside which slides, integral with the end of the rod 75, run.

Alternatively, to allow the rod to move farther in relation to the axis of the carousel, it is possible to use telescoping extension systems connected to the ends of the rods and to the supporting seats. In an equivalent solution a pantograph system may be provided. In any case, access to the various workpiece-holders is facilitated, in a per se known manner, by the presence of free wheel mechanisms associated with the various toothed wheels, which allow free rotation of the rods 75 around their axes in the opposite direction to the direction of rotation adopted in the planetary movement around the axis A-A of the carousel. Fig. 13 shows a braking mechanism (omitted for clarity of the drawing in the other figures) fitted on the port 11 B. A similar layout is provided on the port 11 A. The mechanism has a shaft 205 coupled on an extension of one (9B) of the pins 9A, 9B of the hinge 9. Brake blocks 209, carried by a support 211 fixed to the port 11 B, act on a disk 207 fixed to the shaft 205. The hinge 9 is fitted so that the pin 9A allows only slight oscillation to adapt the position of the closing port 11 B in relation to the fixed central body 3 during closing, while the actual hinge pin is constituted by the pin 9B. This is fixed in relation to the central body 3 and the port 11 B rotates around it. A modified layout is also possible in which the pin 9B rotates and the braking device 209, 211 is provided integral with the fixed central body 3.

The brake associated with the port may also be utilized on a vacuum metallization system without the other characteristics described above relative to the conformation of the carousel and/or the diffuser nozzle. Similarly, the supporting mechanism of the rod 75 which allows it to move away from the axis A-A of the carousel (by opening and closing the articulated arms 201 , 203) may also be used in systems having a carousel with different configuration.

It is understood that variations and modifications may be made to the invention without however departing from the scope of the concept which forms the finding. Any reference numerals in the attached claims are provided for the sole purpose of facilitating reading in relation to the description above and to the attached drawings, and do not in any way limit the scope of protection.

Claims

Claims 1. A system for vacuum metallization of objects treated in batches, comprising: a vacuum chamber, at least one carousel (23) rotating around an axis of rotation (A-A), which is positioned inside said vacuum chamber when the system is operating; associated with said at least one carousel, a first flexible element (61) closed in a loop and connected to said vacuum chamber, driven around a first series of driving wheels (25, 25A, 25B) supported by said carousel (23); associated with said at least one carousel, a second flexible element (63) closed in a loop and connected to said vacuum chamber, driven around a second series of driving wheels (27, 27A, 27B) supported by said carousel; associated with each wheel of said first and said second series, respective seats for engaging corresponding rods (75) to support workpiece- holders^" (81 , 81 A, 81 B, 83, 83A, 83B) for said objects, with torsional coupling means (37, 47, 57) between each rod and the respective driving wheel.

2. System as claimed in claim 1 , wherein the supporting rods associated with the wheels of the first series have workpiece-holders with smaller dimensions and the supporting rods associated with the wheels of the second series have workpiece-holders with larger dimensions.

3. System as claimed in claim 1 or 2, wherein said first and said second flexible element lie on two parallel geometric planes.

4. System as claimed in one or more of the previous claims, wherein the driving wheels of said second series are positioned with their axes at the vertices of a polygon, and at least some of the driving wheels of the first series are positioned with their axes outside said polygon.

5. System as claimed in claim 4, wherein at least one driving wheel of said first series of driving wheels is coaxial with a corresponding driving wheel of the second series, the remaining driving wheels of the first series being positioned with their axes outside the polygon at the vertices of which the axes of the wheels of the second series are positioned.

6. System as claimed in claim 5, wherein said second series comprises six driving wheels and said first series comprises eight driving wheels, the wheels of the second series being positioned equidistant from one another in line with the vertices of an equilateral hexagon, the wheels of the first series being positioned at the vertices of a non-equilateral octagon.

7. System as claimed in one or more of the claims from 1 to 5, wherein said first series comprises ten driving wheels and said second series comprises six or eight driving wheels.

8. System as claimed in one or more of the previous claims, wherein said carousel has a discoidal element (21), from one face of which said rods (75) extend, said first and said second series of driving wheels and said first and said second flexible element being positioned on the other face of the discoidal element (21 ).

9. System as claimed in claim 8, wherein each of said seats comprises a hollow shaft (31 , 41 , 51) coaxial with the respective driving wheel and extending through said discoidal element from one face to the other face.

10. System as claimed in claim 8 or 9, wherein said carousel comprises a second element (71) connected to said discoidal element (21) via respective uprights (73), with said rods extending between said discoidal element and said second element, each rod being connected, with the end opposite to said discoidal element, to a support (77) connected to said second element.

11. System as claimed in one or more of the previous claims, wherein free wheel mechanisms are provided between said driving wheels and the respective seats for said rods, to allow free relative rotation between the seat and the driving wheel in one relative direction and prevent relative rotation in the opposite direction.

12. System as claimed in one or more of the previous claims, wherein a mechanism (201 , 203) is associated with at least one of said seats for said rods, to allow movement of the respective rod to facilitate access to the central area of the carousel.

13. System as claimed in claim 12, wherein said mechanism comprises at least one pair of articulated arms.

14. System as claimed in one or more of the previous claims, wherein said vacuum chamber is formed by a fixed body (3) and by at least one closing port (11 A, 11B) which with said body forms the vacuum chamber, a seal (107) being provided between the body and the port, and wherein next to said seal, in the dimension of its thickness, between the body and the closing port, at least one diffuser (103) is positioned to distribute, inside the vacuum chamber, a product to form a protective coating on the metallized objects.

15. System as claimed in claim 14, wherein said diffuser extends tubularly parallel to said seal.

16. System as claimed in claims 14 or 15, wherein the vacuum chamber defined by said body and by said closing port extends substantially cylindrically with a circular section.

17. System as claimed in claims 14 or 16, wherein said seal is held in place between an internal strip (113) and an external strip (111) extending along a closing edge of said body, and wherein said diffuser is positioned next to said internal strip, between it and the inside of the vacuum chamber.

18. System as claimed in one or more of the claims from 14 to 17, wherein said diffuser has a plurality of gauged holes distributed along the longitudinal extension of said diffuser, with diameter increasing from a first end (103A) to a second end (103B) of said diffuser, the first end of the diffuser being connected to a supply duct (105) of the product to diffuse in the vacuum chamber and the second end being closed.

19. System as claimed in at least claim 16, wherein two closing ports are hinged to said body, designed to cooperate alternately with the body to form with it the vacuum chamber, and wherein said seal and said diffuser are fixed to the closing edge of the body forming the vacuum chamber.

20. System as claimed in at least claim 17, wherein said diffuser is supported by clamping brackets (105), fixed to said inner strip (113).

21. System as claimed in one or more of the previous claims, wherein said flexible elements are chains and said driving wheels are wheels for chains.

22. System as claimed in at least claim 15, wherein said at least one carousel is supported by the closing port.

23. System as claimed in at least claim 19, wherein a respective carousel is associated with each of said two closing ports.

24. System as claimed in one or more of the previous claims, wherein said vacuum chamber is formed by a fixed body (3) and by at least one closing port (11 A, 11 B) joined to it via articulated hinges (9), and wherein a brake (205-211) is associated with at least one of said hinges.