Abstract:
A detachable inking device for a flexographic printing machine, a manipulating device for removing and replacing the inking device, a cleaning device, and a repair station for refurbishing the inking device. The inking device itself is a chambered doctor blade ( 9 ) mounted on two lever-supports ( 13, 14 ) through which ink is supplied from a reservoir. The lever-supports are rigidly attached to a shaft ( 11 ) which is pivotable between the frames ( 34 ) of the flexographic printing machine. The chambered doctor blade has a body ( 25 ) made of light material, crossed at one of its ends by a tube ( 26 ) emerging from the bottom ( 28 ) of body ( 25 ), and at the other end by a tube ( 40 ) having its opening part ( 29 ) at level with the bottom ( 28 ) of the body ( 25 ). The latter rests on seals ( 38, 39 ) secured to the lever-supports ( 13, 14 ) to which are attached centering and fixing means ( 17, 18 ) allowing a quick loosening of the chambered doctor blade ( 9 ) without the help of any tool. The body ( 25 ) comprises two planar outwardly slanted projecting parts against which are adhesively attached two doctor blades elements. The doctor blade elements are also held at their ends by a supporting piece ( 21 ) having two supporting flanges ( 35, 36 ) that engage the ends of the doctor blade elements ( 19, 20 ).

Description:
This application is a division under 37 C.F.R. §1.53(b) of application Ser. No. 09/517,476, filed Mar. 2, 2000, by Gilbert Bardet, et al. entitled DETACHABLE INKING DEVICE FOR A FLEXOGRAPHIC PRINTING MACHINE, ITS EMBODIMENT, CLEANING AND USE IN SUCH A MACHINE. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention refers to a detachable inking device for a flexographic printing machine, its embodiment, cleaning and use in such a machine. 
     2. Description of the Related Art 
     The flexographic printing machines and, more particularly the printing stations of these machines comprise a plate cylinder, a pressure roller, a screen cylinder, commonly called anilox cylinder by the experts, and an inking device. The matter to be printed passes between the plate cylinder and the pressure roller. The screen cylinder, on which ink has been previously applied by the inking device, deposits the ink on the plate cylinder. To obtain four-color prints, for example, four printing stations are used, each printing a different color. The inking devices, being generally used in the printing machines to deposit ink on the screen cylinder, are made up of a chambered doctor blade comprising a body on which are mounted two doctor blades coming in contact with the circumference of the screen cylinder. The ends of the chambered doctor blade are sealed by seals. The assembly thus formed consistutes a tank or chamber, into which the ink is supplied through an inking circuit, by means of a pump. 
     Obviously, the printing machines, such as referred here, must be easily set up for different printing jobs and in order to do so, all the components of each printing station need to be thoroughly cleaned. This thorough cleaning is relatively easy for components such as the plate cylinder and the screen cylinder but is more difficult as regards the chambered doctor blade, on which ink residues often remain even after an intensive cleaning. 
     Each document U.S. Pat. Nos. 4,590,855, 5,150,651, EP 0 359 959 B1 and EP 0 611 649 B1 describe an inking devices being similar to the one we have just referred to. 
     The document U.S. Pat. No. 4,590,855 relates to a chambered doctor blade wherein the doctor blades are mounted on a body by means of a small bar and a hexagonal head screw. The tightness of the chambered doctor blade ends is achieved by a seal cut according to the diameter of the screen cylinder. An identical seal is fixed to each end of the chambered doctor blade body by means of a small plate crossed by hexagonal head screws ensuring the clamping of the assembly. This chambered doctor blade is arranged so as to be pivotable from a working position against the screened cylinder to a rest position in which it is relatively easy to exchange used or damaged doctor blades. Obviously, in this position, an additional operation, for example cleaning, can be carried out because of the access to the internal parts of the chambered doctor blade. 
     The document U.S. Pat. No. 5,150,651 describes a chambered doctor blade wherein the doctor blades are also mounted on the chambered doctor blade body by means of a small bar and a hexagonal head screw. In this device, the concern is depositing ink in some transverse areas of the screened cylinder. For this purpose, the tightness of these areas, in the chambered doctor blade, is provided by seals which are cut according to the diameter of the screened cylinder and the configuration of the internal part of the chambered doctor blade. Once that these seals are in the required position, they are maintained by the clamping of the doctor blades acting on a part of the seal. This chambered doctor blade is also arranged so as to be pivotable from a working position against the screen cylinder to a rest position in which it is relatively easy to exchange used or damaged doctor blades and to adjust the position of the seals in the width of the chambered doctor blade. Also obviously, in this position, an additional operation, for example cleaning, can be carried out because of the access to the internal parts of the chambered doctor blade. 
     The document EP 0 359 959 B1 refers to a doctor blade inking device comprising a chambered doctor blade being detachably fixed on a crossbar which extends parallel to the screen cylinder. The crossbar includes fastenings for fitting or removing of at least one chambered doctor blade. The doctor blades are secured to the chambered doctor blade body in the same manner as has just been described with reference to the two previous patents. The assembly formed by the crossbar and the chambered doctor blade is also pivotable from an operating position to a rest position allowing the same handling operations as those previously cited in relation with the two mentioned U.S. patents. 
     The document EP 0 611 649 B1 relates to an inking apparatus wherein the doctor blades are held against the chambered doctor blade body by a clamping means comprising levers controlled by cylinders for clamping and loosening the doctor blades. In this device, the doctor blades are of magnetic material, such as a magnet, for temporarily holding the doctor blade against the chambered doctor blade before clamping it by the clamping device. This assembly, as those previously described, is also pivotably mounted in order to be able to carry out operations which are similar to the above-mentioned, this in a rest position. 
     As will be noted, in all the described devices the fitting and the fixing of the doctor blades achieves by means of clamping means consisting either of screws or of lever and cylinder devices applying their clamping force in unifrom manner all along the doctor blade. In one of the cited examples, it has been endeavoured to improve the contact between the doctor blades and the chambered doctor blade body by using a magnetic material for the doctor blades and a ferrous material for the chambered doctor blade body. As has been explained, the inking means need to be thoroughly cleaned at each change of color of the printing stations. Such a cleaning is also required when replacing a used or damaged doctor blade. 
     One of the major disadvantages of the devices using spaced clamping means lies in the fact that, when cleaning the chambered doctor blade there always remain ink residues attracted by capillarity between the internal part of the doctor blade and its supporting surface against the chambered doctor blade body. This phenomenon is particularly undesirable when changing from a dark color, for example black or blue, to a light color such as yellow. This lack of cleaning causes a fading of the desired new color, which is obviously unacceptable. 
     Another important disadvantage remains in the long time required for exchanging a used or damaged doctor blade. This is essentially due to the required removal and refitting of the numerous components which comprise the clamping means. Finally, the chambered doctor blades used in the known devices are of a heavy construction which renders their handling difficult when withdrawing them from the printing machine, which is required, for example for a repair or a thorough cleaning. 
     BRIEF SUMMARY OF THE INVENTION 
     The aim of the present invention is to obviate the above-mentioned disadvantages and proposing a detachable inking device comprising an extremely lightweight chambered doctor blade. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be more clearly understood from the following description of an embodiment of an inking device for a flexographic printing machine given by way of non-limitative example and illustrated by the accompanying drawings, in which: 
     FIG. 1 is a schematic side view of a printing station, 
     FIG. 2 is rear view, in elevation, of a chambered doctor blade, 
     FIG. 3 is a plan view of the chambered doctor blade of FIG. 2, 
     FIG. 4 is a view according to A of FIG. 2, 
     FIG. 5 is a sectional view according to V—V of FIG. 2, 
     FIG. 6 is a sectional view according to VI—VI of FIG. 2, 
     FIG. 7 is a perspective view of one of the ends of the chambered doctor blade, 
     FIG. 8 is a perspective view of the handling device of the chambered doctor blade, 
     FIG. 9 is a perspective view of the automatic washing device of the chambered doctor blade, 
     FIG. 10 is a general perspective view of the gluing and ungluing device of the doctor blades, 
     FIG. 11 is a perspective view of the gluing-ungluing means of the corresponding device, and 
     FIG. 12 is a front view of the gluing-ungluing means. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 is a schematic side view of a printing station  1  wherein are represented the components of such a station. The sheets to be printed  2  are conveyed in a manner that their lower surface can be printed without interference from the lower conveyor means. For this purpose, means such as suction conveyors  3  are used, including drive rollers  4  secured to a suction device  5 . The sheets to be printed  2 , conveyed by the suction conveyors  3 , are printed by a plate cylinder  6  cooperating with a pressure roller  7 . The plate cylinder  6  receives the ink from a screen cylinder  8 , commonly called an “anilox” cylinder. The screen cylinder  8  receives the required ink through a chambered doctor blade  9 . This chambered doctor blade  9  is generally fixed on a blade support  10 , which is pivotable, in the direction shown by arrow  12 , about an rotational axis  11 . This pivoting enables the chambered doctor blade  9  to be brought in a horizontal position in which, for example, the chambered doctor blade may be cleaned or replaced, the end seals renewed, and, finally, the blade completely removed. These are often relatively tedious operations requiring the use of tools for loosening the fixing means of the chambered doctor blade  9  from its support  10 . 
     FIG. 2 is a rear view, in elevation, of a chambered doctor blade  9  illustrating the manner of connecting the chambered doctor blade  9  with its rotational axis  11  by means of a support assembly including lever-supports  13  and  14  in which are fastened fittings such as nipples  15  and  16  for the supply and return of the ink in the chambered doctor blade  9 . The connection between the lever-supports  13  and  14  and the chambered doctor blade  9  is ensured by means of seals  38 ,  39  (see FIGS.  5  and  6 ), so that the chambered doctor blade  9  can be disconnected from its levers-supports  13  and  14  without having to remove the ducts supplying or withdrawing the ink from the chambered doctor blade  9 . This kind of connection between the chambered doctor blade  9  and its levers-supports  13  and  14  allows a simple extraction without any problem of the chambered doctor blade  9  from the printing station  1  so that all the required handling operations can be performed outside the machine. The lever-supports  13  and  14  are moreover equipped with centering and fixing means  17  and  18 . These centering and fixing means  17  and  18  are of any suitable commercially availabe type and are well-known to those skilled in the art. These allow a quick loosening of the chambered doctor blade  9  without the help of any tool. 
     FIG. 3 is a top plan view of the chambered doctor blade of FIG. 2 representing the various components of FIG. 2 with identical reference numerals. 
     FIG. 4 is a view looking in the direction of arrow A of FIG. 2 representing one of the ends of the chambered doctor blade  9 . This figure shows in particular the manner in which upper and lower doctor blade elements  19  and  20  are held at their ends by means of a supporting piece  21  cooperating with the end seal  22  of the chambered doctor blade  9 . The supporting piece  21  is secured against the end seal  22  of the chambered doctor blade  9  by means of two knurled screws  23  and  24 . 
     FIG. 5 is a sectional view according to V—V of FIG. 2 representing the body  25  made of aluminium or any other light material such as composite materials, used for the body of the chambered doctor blade  9 . The outlet  27  of the ink tube  26  emerges from the bottom  28  of the chambered doctor blade body  9  so as to avoid escapement of the residual ink from the chambered doctor blade  9  when withdrawing it from the printing station  1  and, for example, during its transport to a cleaning station provided in the press room. This figure also shows the seal  39  arranged in the lever-support  13  and ensuring the tightness between the chambered doctor blade  9  and said lever-support  13 . The doctor blades  19  and  20  are also shown in this figure and the manner of fixing them to the chambered doctor blade body  9  will be given further in the present description. 
     FIG. 6 is a sectional view according to VI—VI of FIG. 2 showing the ink supply tube  40  connected to the joining piece  16 . The opening part of the ink supply tube  40  is at level with the bottom  28  of the chambered doctor blade body  9  to provide an almost complete outflow of the ink remaining in the chambered doctor blade  9  when the machine is not in operation. As will be seen hereinafter, this opening will be sealed by an adequate seal belonging to a safety and handling device of the chambered doctor blade  9 . 
     FIG. 7 is a perspective view of one of the ends of the chambered doctor blade  9 . The other end of the chambered doctor blade  9  is similarly constructed. FIG. 7 shows the chambered doctor blade  9  in its rest position, i.e. when it is not in contact with the screen cylinder  8 . The chambered doctor blade  9  is fitted between two lateral frames  34 , only one of which is shown. In particular, this figure shows the manner of holding the ends of the doctor blades  19  and  20  by the supporting piece  21  which has two supporting flanges  35  and  36  that maintain the ends of the doctor blades  19  and  20  in contact with their supporting surfaces on the end seal  22 . Also represented here is the guiding slide  37  which allows easy positioning of a manipulator  55  (see FIG. 8) on the chambered doctor blade  9  when it is to be withdrawn from the printing station  1 . The guiding slide  37  is fitted against the internal surface of each lateral frame  34  by means of screws (not shown). 
     FIG. 7 clearly shows that the doctor blade elements  19  and  20  are not held by mechanical means. The doctor blade elements  19  and  20  are made of a non-oxidizing steel strip whose thickness may vary in dependence on the jobs to be carried out but preferably having a thickness of 0.15 to 0.2 mm. This non-oxidizing steel strip receives, before being applied against the upper supporting surfaces of the chambered doctor blade  9  and after having been degreased and dried, a gluing means  48 , e.g. an adhesive layer. The non-oxidizing steel strip provided with the gluing means  48  is then mechanically applied, with a certain pressure, against the supporting surfaces of the chambered doctor blade body  9 . This solution thus enables complete removal of the capillarity effect, which arises with conventional fixing means of doctor blades, and also allows the exchange of damaged or used doctor blade elements  19  and  20  by peeling, using the same apparatus as for the gluing of the doctor blades  19  and  20 . The combination of a light chambered doctor blade body and adhesive attachment of the doctor blade elements provides a chambered doctor blade having a considerably lighter weight than the existing chambered doctor blades, thus allowing easy handling. 
     This easy handling of the chambered doctor blade  9  as well as the simplicity of removal from the machine thus allow quick exchange with another chambered doctor blade which has been previously cleaned and possibly repaired outside the machine by means of auxiliary devices which will be described now. The advantage of operating outside the machine is that it is simultaneously possible to carry out printing jobs and prepare intending tasks “en temps masqué”. A manipulator  55  is used to-extract the chambered doctor blade  9  from the printing station  1 , thus keeping an excellent safety level. 
     FIG. 8 shows one of the ends of a manipulator  55 . The other end being practically similar, apart from a sealing mechanism  56 , it will not be described here. The manipulator  55  consists of a channel member  57  adapted to cover the upper part of the chambered doctor blade  9 . This channel member  57  is equipped with two fixing or securing devices  58  (only one of which being shown in this figure, the other, identical one, being located at the same place at the other end of the channel member  57 ). 
     In addition, each end of channel member  57  is provided with a guiding block  59  which facilitates the positioning of the manipulator  55 . The guiding blocks  59  engage the guiding slides  37  shown in FIG.  7 . 
     The sealing mechanism  56  is compised of a conical seal  60  mounted on the upper part of the channel member  57 . The conical seal  60  is adapted to seal the outlet  29  of the ink supply tube  40  so as to prevent leakage from the chambered doctor blade  9  when it is to be extracted from the printing station  1 . The securing device  58  consists of a plate  63 , which is pivotally mounted about an axis  64  on the upper part of the channel  57 . The plate  63  is provided with two small clamping plates  65  and  66  carried by a spacer  67 ,  68  respectively. The small clamping plates  65  and  66  have a slanted plane such as  69  acting as cams when rotating opposite to the direction shown by the arrow  70 , against the lower surface of the chambered doctor blade  9 , thus securing it to the manipulator  55 , as shown in the present figure. Security device  58  is locked in the clamping position shown in this figure, by means of a bolt  71 , which is manually actuated so as to allow rotation, in the direction shown by the arrow  70 , of the securing device  58  when it is required to withdraw the manipulator  55  from the chambered doctor blade  9 . Each plate  63  is additionally provided with a handle  72 . This system allows locking and unlocking of the manipulator  55  with only one finger without releasing the transporting handles  72 . One of these auxiliary devices, required for the above-mentioned handling of the chambered doctor blade  9 , consists of an apparatus such as the one represented in FIG.  8 . 
     FIG. 9 shows an automatic washing device  80  for cleaning the chambered doctor blade  9  outside the machine. This device consists of a frame  81 , inside of which moves a washing head  82  along the chambered doctor blade  9  which has been previously placed on two hollow supports  83  and  84  by means of the manipulator  55 . The support  84  is provided with a centering pin  85  which makes the adjusting of the placing of the chambered doctor blade  9  on these supports easier. The washing head  82  is equipped with two rotary brushes  86  and  87  as well as a plurality of washing nozzles  88 . The rotary brushes  86  and  87  are arranged so as to be able to clean at best the surfaces of the doctor blades  19  and  20 , and the nozzles  88  are judiciously oriented so as to remove all ink residues on the chambered doctor blade  9 . 
     The displacement of the washing head along the chambered doctor blade is ensured by a motor mounted in a casing  89  on the washing head  82 , which moves along a toothed belt  90  fixedly tightened between the lateral walls of the frame  81 . This bidirectional displacement is guided by a cylindrical bar  91  and a carrying rail  92 . The front surface of the latter is equipped with two supports  93  and  94  adapted to receive the manipulator  55  for storing it. Finally, a control panel  95  allows controlling of said washing device  80 . 
     FIG. 10 is a general perspective view of the device  100  for gluing and ungluing the doctor blade elements  19  and  20  to and from the chambered doctor blade  9 . This device comprises a table  101  on which are attached securing jigs  102  to facilitate the adequate positioning of the chambered doctor blade  9  in the device  100 . Two longitudinal semicircular receptacles  103  and  104  are located on opposite sides of jigs  102  for directly receiving the respective used doctor blades  19  and  20  when they are removed from the chambered doctor blade  9  by the present device  100 . 
     Along the longitudinal edes of the table  101  are mounted two bars  105 ,  106  on which travels a carriage  107  consisting of two half plates  108 ,  109  which slide on the bars  105 ,  106  by means of two pairs of blocks  110 . The two half plates are secured to one another by a circular rail  111  screwed on their upper surface. On this circular rail turns a large ring  112  on which is mounted a gluing-ungluing station  120 . The displacement of the carriage  107  can be done manually by means of a handle  113  the carriage can be motorized. A desk  114  allows to control the compressed air supply system of certain parts of the gluing-ungluing station  120 , more particularly the parts for application, sectioning, degreasing and drying of the doctor blade elements. 
     FIG. 11 is a perspective view of the gluing-ungluing station  120  of the corresponding device  100 . This includes a slanted plate  121 , on the front surface of which are mounted various components for the automatic placing of, firstly, a gluing means  48  (FIG. 12) against a metal strip  126 , then secondly and simultaneously, pressing strip  126  against the two supporting surfaces forming the lips of the chambered doctor blade body  9 . Being sectioned to the right length, strip  126 , in the end, forms the doctor blade elements  19  and  20  mounted on the chambered doctor blade body  9 . 
     In a preferred but non-limitative embodiment, the gluing means  48  is a double-faced adhesive tape fed from a supply roller  122 , which is rotatably mounted on the front surface of the plate  121 . As shown in FIG. 12, this adhesive tape is covered by two removable protective tapes  123  and  125 . Upper protective tape  125  passes in the following order, around rods  130 ,  131  and  132 . Lower protective tape  123  passes around rods  130 ,  134 ,  135 ,  136  and  132 . After being separated from the adhesive tape  48 , the two protective tapes  123  and  125  both pass around a driven collector shaft  137 , against which a tension roller  138  is applied, then winds around a rewinder shaft  139 . A support  128  for a metal strip roller  127 , is also mounted on plate  121 . 
     A housing  140 , which is likewise fitted against the latter, contains the cleaning device or station for strip  126 . The latter comprises a sprayer  141  (FIG. 12) for spraying a degreaser and a dryer. The fluid is contained in a tank  142  located above the housing  140 . A vertical bent channel  143  is used to support compressed air ducts which open into the housing  140  and are connected to the control desk  114  (FIG.  10 ). During cleaning, the strip  126  passes in a supply channel  144  being topped at one end with a guiding box  145  for adjusting the adhesive tape  48 , which has been separated from its upper protective tape  125 , against the cleaned surface of strip  126  in order to glue it. Then, the latter passes around a drive shaft  146  before the second protective surface  123  is separated from the adhesive tape  48  at the level of the rod  134 . At this stage, strip  126  is already in a pressing mechanism  147  such as a roller or a pressure shoe which applies the adhesive surface of the latter against the upper supporting surfaces of the chambered doctor blade body  9 . A cutter  148  for strip  126  is located directly behind and above this pressure means  147  and comprises a guillotine actuated by a cylinder. The pressure means  147  and the cutter  148  are both likewise pneumatically controlled by the desk  114 . 
     The gluing-ungluing station  120  is turnable in a vertical plane owing to circular rail  111  and the ring  112 , so that the gluing and ungluing operations can be carried out on both lips of the chambered doctor blade body. The accuracy of the angular rotation of the means  120  is ensured by a finger  149  adjusting in perforated holes in the circular rail  111 . The used or damaged doctor blades are unglued by an ungluing mechanism  150  which is mounted against the upper surface of the ring  112 . This lifts the doctor blade by a tail provided at one of its ends and unglues it, with the adhesive tape, and drops into the receptacles  103 ,  104  having the shape of gutters (FIG.  10 ). 
     FIG. 12 is a front view of the front part of the plate  121  on which are mounted the various elements previously described with reference to FIG.  11 . According to the different arrows in this drawing, the latter illustrates the paths of strip  126 , the adhesive tape  48  and the two protective tapes  123  and  125 . Two belts  151  and  152  are also represented, though being located behind the plate  121  on pulleys secured to the shafts  139  and  146  for the belt  151 , and  137  and  146  for the belt  152 . Obviously, the pulley (having two grooves) of the shaft  146  is driven by the unwinding of the strip  126  applied on the upper supporting surfaces of the chambered doctor blade body, thus advantageously avoiding any adverse synchronism between the unwinding speed of this foil and the displacement speed of the carriage  107  along the bars  105 ,  106 . 
     Numerous improvements can be made to this device, embodiment, cleaning and use in a flexographic printing machine within the scope of the claims.