Abstract:
An apparatus for flow-line treatment of articles has two chambers. The first chamber is a vacuum working chamber to treat articles in an artificial atmosphere. First transport means transport articles through the first chamber and at least one lock at the end of the chamber. Second transport means transport articles though the second chamber. The lock has a movable body with at least two cavities, installed inside an airtight shell. The movable body moves between a first position, in which one cavity connects with the first chamber and the first transport means extend into the cavity, and a second position, in which the cavity connects with the second chamber and the second transport means extend into the cavity. The at least two cavities are adjacent and similar and are provided with openings. Each cavity holds one carrier with articles. The first and second transport means provide simultaneous and antiparallel movement.

Description:
BACKGROUND OF THE INVENTION 
     Generally this invention relates to an apparatus for flow-line treatment of articles in an artificial medium different from ambient atmosphere. 
     More specifically, the invention relates to an apparatus serving for flow-line treatment and coating articles, preferably three-dimensional parts, in an artificial gas medium or in vacuum. A feature of this apparatus is that operation of the treatment means and preset characteristics of the artificial medium are maintained much longer than it is necessary for treatment of a solitary article, and these articles are transported along the treatment zones through the locking chambers. Application of the apparatus of this type is well known for treatment of flat thin articles such as architectural glass, compact disk blanks or chips. However, apparatus of this type may be used most widely in the systems of deposition of metals or their compounds in high vacuum or an atmosphere of inert or reactive gases. 
     Another specification of the field of application is the apparatus for the flow-line treatment of certain number of articles, that is sets of parts fixed on a common carrier and transported as a whole during the process. Application of such apparatus is known for manufacture of small sized articles such as optical lenses, car light reflectors with antireflection or light reflecting coating mainly on one of the sides. 
     In a specific embodiment the proposed invention is an apparatus for flow-line treatment of the sets of articles on carriers in artificial and vacuum media, providing all-round metal or metal-containing coatings on three-dimensional articles such as plastic parts. 
     An apparatus for continuous metallizing of components, U.S. Pat. No. 5,622,564 of Apr. 22, 1997 was considered as the prior art. The apparatus comprises: 
     at least one vacuum working chamber provided with treatment means for processing of the articles; 
     means for maintaining the artificial atmosphere in the working chamber; 
     locks in ends of the vacuum working chamber; 
     a set of carriers for transportation the articles under treatment through at least one working chamber and the locks; and 
     loading and unloading devices in the ambient atmosphere and transport means for carriers. 
     In the prior art, the flow-line apparatus comprises the working chamber and locking chambers at its ends that all are arranged along a common horizontal line. The locking chambers with shutters are separated by gates between themselves and from the atmosphere. All chambers along their length are provided with rails, which form a general track for carriers travel, with travel drives, travel holdup stoppers, as well as with air evacuation and admittance means. 
     The working chamber is provided with a metal vapour source. Metal is supplied for evaporation in the form of wire. The carriers for components are made as carriages, comprising holders of the components, fixed to be rotating relative longitudinal horizontal axis and driven into revolution when stoppers delay carrier transportation. 
     As the design of the flow-line gates or of locks is not described in the prior art patent, it gives a ground to consider them in similar to known units, as for example described in EP-A-0 554 522 of Aug. 11, 1993. 
     Such unit comprises a stationary part in the form of opening and corresponding shutter, closing this opening. 
     The shutter is provided with means for effective travelling along the opening and force movement to deform resilient sealing, which is along the opening perimeter. 
     In this case the closed structure must resist significant forces arising at a pressure difference on the shutter. Pointed out circumstances are determined by the basic disadvantage of all similar units—their restricted operation speed (due to the movement character) and quick wearing out or the sealant exposed to constant changes of stress conditions within a significant part of elasticity range of the shutter material. 
     FR-A-1.496.205 describes an apparatus for flow-line treatment of articles under artificial atmosphere, the said apparatus comprising: 
     at least one vacuum working chamber provided with treatment means for processing of the articles; 
     means for maintaining the artificial atmosphere in the said working chamber; 
     locks in the ends of the vacuum working chamber; 
     transport means for transporting the articles through at least one working chamber and the locks; 
     loading and unloading devices in the ambient atmosphere, and 
     transportation means wherein each of the locks comprises a movable body, installed inside airtight shells, the body comprises at least one cavity; 
     the body is movable between a first position, in which the cavity is in connection with the first chamber and the transport means in the first chamber extends into the cavity, and a second position, in which the cavity is in connection with a second chamber, being located at the other side of the lock, while the transport means in the second chamber extend into the cavity; and wherein the gap between the shell and the body is an air gap seal. 
     In this prior art document both at the supply side and at the unload side a lock or a set of locks is required. This leads to a costly construction. 
     SUMMARY OF THE INVENTION 
     One object of the present invention is to provide such an apparatus which can be built at lower costs. 
     This aim is reached in that the body comprises at least two cavities, which are adjacent and similar and are provided with openings, 
     that each cavity is made with the volume for one, carrier with articles; and 
     that the transport means are made for simultaneous and antiparallel movement in both paired locking compartments. 
     This aim is reached in that the body comprises at least two cavities, which are adjacent and similar and are provided with openings, 
     that each cavity is made with the volume for one carrier with articles; and 
     that the transport means are made for simultaneous and antiparallel movement in both paired locking compartments. 
     The loading/unloading unit is in communication with the locking compartments of the locks at one position of the latter. 
     At the opposite position the adjacent locking compartments are communicated with the compartments of the next locks. 
     Another end of the apparatus is formed by a lock between two chambers with the highest vacuum in the system and has no output to the ambient atmosphere. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Details and interconnections of some embodiments of the suggested invention are presented graphically in nine figures, identified as FIGS. 1-9. 
     FIGS. 1-3 comprise the diagrams of horizontal cross sections of the apparatus embodiments (it should be mentioned here that in FIGS. 1-3 carriers  6  with articles are shown simplified as one whole). 
     FIG. 1 shows a fragment of the loading part of the apparatus in the simplest embodiment. 
     FIG. 2 shows an embodiment of the apparatus with nonreversible transportation of the carriers with the articles. 
     FIG. 3 shows the apparatus embodiment of all-round activation and deposition of three-dimensional articles with the joint loading/unloading unit at one end of the system. 
     FIGS. 4 and 5 comprise more detailed drawings of the locks cross-sections with various versions of the bodies of rotation. 
     FIGS. 6 and 7 show front and side views of the carrier in an interaction with means of its fixation and transportation. 
     FIGS. 8 and 9 show the means of the articles transportation in the working chamber. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A lock  1 , which is presented in FIG. 1, is formed by a body of revolution  2 , placed with minimum clearance  3  in a sealed shell  4  and containing cavity  5 , into which a carrier  6  with articles may be introduced. The carrier  6  is fixed in the cavity  5  with drive rollers  8  and bearing rollers  9  along the bearing path  7 . These rollers form the means of transportation of the carriers  6  with the articles inside and outside the cavity  5 . A shell  4  is connected to and may communicate with a loading unit  10 , containing similar rollers  8  and  9  as the transportation means. 
     At the opposite end the shell  4  is connected to and may communicate with the next component  11  of the apparatus. Here another lock is shown as the next component, but it may be a working chamber as well. As necessary the shells  4  and/or their joints with each other can be connected also to means with working media displacement (marked with wide arrows in all drawings), for example, as appropriate vacuum pumps, inlet valves and their combinations. 
     Locking processes of the apparatus are performed in alternating phases of medium displacement and transportation of the carriers with articles through the locks, divided by unidirectional ¼ or ½ revolutions of the body of revolution and changing position of the cavity  5  axis into longitudinal or transverse position. It is preferable to make the revolutions uniformly accelerated, changing acceleration sign at the medium point of the revolution at possible minimum duration of the operation. 
     The rollers  8  and  9  operate in similar way during movement of the carriers  6 , but only in moments when axis of the cavity  5  is parallel to general axis of the apparatus and with alteration of the operation direction in accordance with the position of the open end of the cavity  5 . The bodies of revolution of all the apparatus rotate with equal or half-value frequencies, preferably, with lagging by the value of single revolution duration. Operation of the rollers  8  and  9  of adjacent legs in the direction of transportation should be cophased and synchronous. 
     In case of the above described design and operation bodies of revolution  2  and shells  4  form the locks with the chambers in the form of the cavities  5 . Each couple of adjacent locks forms a locking stage in the form of combination of adjacent locking cavities and interspaces between them. Dynamic resistance to gas flows along rather long and narrow gaps  3  serves as means of locking spaces separation instead of moving shutters with resilient seals, as in the prior art. Conductivity of the gaps is determined to a great extent by the gap width. Therefore it is possible to limit gases inflow value by minimising this width during locking cycle down to a value not greater than a fraction of the cavity free volume, taking into account dynamics of the process. Absence of quickly weared out parts is the advantage of such technical solution. This increases lifetime and reliability of the apparatus, when only simple revolution movement mainly against inertial forces is necessary. That allows also to increase operation speed. In the simplest embodiment, shown in FIG. 1, complete locking cycle demands one revolution of the body of revolution  2 . 
     In an improved embodiment number of locking cycles per one revolution may be doubled to increase operation speed. Such an example is schematically shown in FIG. 2, where the input end of the apparatus is at the stage of carriers transportation: the loading arrangements  10 , two locks  12  (another embodiment of the locks) and a part of the working chamber  13 . The improvement here is in the following: the cavities of the locks  12  are provided with bulkheads  14  between two locking compartments  5  and the carriers transportation means (not shown) are able to operate synchronously but in opposite directions. In this particular case openings  15  are arranged to provide the locks reloading in half a revolution of the body of revolution  2 . 
     However, in case of adjacent arrangement of openings  15  the described improvement is more effective, because it enables to provide synchronous locking of counterflows of the carriers with articles. These possibilities are illustrated by a flow-line deposition apparatus, which is schematically shown in FIG.  3 . This apparatus includes a line of connected components capable to communicate with each other in sequence. 
     There is a loading/unloading unit  16  at the beginning of the line and following three locks  17 , an activation chamber  18  with passivation chamber  19 , parallel to the latter, locks  17 , a high vacuum outgassing chamber  20  and a high vacuum deposition chamber  21 , an end lock  22 . The high-vacuum deposition chamber  21  and the high-vacuum outgassing chamber  20  are the working chambers with the lowest pressure in this apparatus. All working chambers are provided with means of carriers transportation, maintenance of required environmental characteristics and corresponding treatment mains (glow discharge electrodes  23  and sources  24  of the deposited material vapours are shown as examples). 
     All locks  17  and  22  comprise two locking compartments  5 , corresponding means of the carriers transportation can operate synchronously in antiparallel directions in these locking compartments. At the end of this apparatus the locking compartments of the lock  22  are made with openings at both ends. All the locks of the apparatus operate as it was mentioned above at consecutive rotations of all the bodies of revolutions by ½ revolution. 
     According to the offered apparatus and its operation character each carrier with articles arrives to the loading/unloading unit and travels further consecutively within parallel counterflows. During transportation surfaces of the articles are exposed consecutively to glow discharge plasma activation, outgassing, coating with metals or their compounds in the deposition chamber and the coating passivation in low pressure oxidising environment or, if necessary, in plasma. 
     Flows of gases in the locks are cut twice, while volumes of counterflows act as an addition to the means of media substitution in the locks. These factors provide additional advantages of the described apparatus in increase of operation speed and, consequently, its productivity. Number of the components, necessary to provide locking process, is decreased. 
     It further decreases wear of the apparatus, improves its reliability. 
     The design of locks  17  or  22  is shown more in detail in FIG. 4, which corresponds to A—A cross section in FIG.  3 . The lock is formed by an airtight shell  4  with the body of revolution  25 , installed inside the shell. In this case the body of revolution  25  is formed by hollow straight cylinder, but it is similar to the body of revolution  2  in other embodiments of the apparatus. The advantage of such solution is that minimum of locking volume is combined with minimum of inertial counteraction to rotation acceleration, while the cylinder has maximum processability during manufacture. 
     In this embodiment the body of revolution  25  may contain inert gas with marker properties, for example, helium at pressure no more than {fraction (1/10)} of atmospheric level, in cavity (cavities)  26 . 
     Such pressure of the inert gas in the airtight body of revolution  25  is a compromise to the pressure outside the surfaces the body of revolution  25 , whose walls have limited rigidity. Under these conditions the pressure inside the body of revolution limits fluctuation of the gaps  3  and  27 , providing, together with other factors, minimum size of the gaps. On the other hand, geometrically complicated walls of the body of revolution, which is continually loaded with alternating pressure forces, need control of their airtightness during long operation of the apparatus. Marker properties of the gas will assist to such control. 
     In the considered embodiment the gap  3  between the body of revolution  25  and the shell  4  is bypassed by the end gaps  27 . Limiting the end gaps width at the level of ½ of the gaps  3  provides sufficient decrease of bypassing effect, if consider at least cubic relationship between throughput capability and the gap width. 
     In another embodiment of the lock, shown in FIG. 5, bypass effect of the end gaps is eliminated by sliding gaskets  28 , and pressure level in the cavities  26  is fixed by their connection with end gaps  27 , which are connected to the medium replacement means. 
     The carriers  6  with articles, schematically shown in FIGS. 1-3, actually are an assembled unit of carriers  29  and articles  30  (FIGS.  8  and  9 ). More in detail the articles carrier and its attitude fixation in interaction with the transportation rollers  8  and  9  are shown in FIGS. 4-7. During transportation through the locks  17  and chambers  18 - 21  the carriers  29  with articles  30  are rotated around their vertical axes. Positioning of the drive rollers  8  and bearing rollers  9  of the transportation means generally does not differ from that, shown in FIG.  1 . 
     The front view of the carrier with articles interacting with the transportation means in the treatment chambers is shown in FIG. 6, where the articles  30 , fixed on holders  31 , provided with supports of articles  33  and sprocket wheels  32  to be rotated. The drive rollers  8  are appropriately coupled with drives (not shown). The drive rollers  8  are positioned relative bearing rollers  9  so, that to have a friction contact with one of the side paths  7  of the carrier  29 . The ends of the carriers  29  have side chamfers  34  for thrust-free engagement into the said contact. 
     During transportation of the carriers  29  (FIGS. 8 and 9) in the treatment zones of the working chambers  18 - 21  with constant speed the sprocket wheels  32  of the carriers  29  interact with a number of pins  35 , made with the possibility to limit counteraction. Thus the holders  31  are involved into rotation, providing all-round treatment of articles  30 . 
     For continual movement of the carriers  29  through the working chambers  18 - 21  each of them should be in contact with two drive rollers  8  at any time. In the end zones of this path movement of the carriers should be changed from pulse mode into uniform mode and back. The end drive rollers with pulse drive and adjacent drive rollers with constant rotation should be equipped with freewheel clutches to eliminate possibility of conflict of these rollers at the carrier, common for them. 
     Industrial application of the invention may be in various areas. Particularly it is determined by the fact, that different metals or their compounds are vacuum deposited onto three-dimensional plastic parts in mass production in batch type vacuum machines, especially if the parts undergo preliminary and subsequent lacquering. Such equipment requires extensive use of manual labour. For such cases the present invention allows to combine all treatment steps into one general cycle with circulation of the carriers with articles, which is a constituent of the present invention.