Abstract:
A dispensing machine for the metered delivery of fluid products, especially painting products. The dispensing machine includes a dispensing head with a nozzle, and the ends of a plurality of delivery ducts communicate with the dispensing head in order to feed a plurality of fluid products thereinto. A mixing device, in particular a rotating turbine, is mounted between the ends of the delivery ducts and the dispensing nozzle to continuously mix the fluid products coming from the different delivery ducts and simultaneously entering the dispensing head.

Description:
TECHNICAL FIELD 
     The present invention relates to a dispensing machine for the metered delivery of fluid products, especially fluid ingredients that make up finished products such as varnishes, paints, inks, enamels, textile dyes and similar products. 
     BACKGROUND ART 
     In order to obtain the finished products given above as examples, it is known to add one or more colorant fluid products to a base fluid, such as white or transparent, in predetermined proportions according to specific formulas. Known machines used in the above industry deliver known amounts of colorants into cans, containers, tins or bins of a predetermined capacity, into which the base fluid products have previously been placed. These known machines must ensure high precision in determining the amount of colorant product to dispense, since even slight differences in the relative proportions among the various colorant products or between these and the base fluid product may lead to finished products having a color that does not match the desired result. At any rate, after delivery by traditional dispensing machines, the distribution of colorant products in the mass of base fluid product is not homogeneous, and it is therefore necessary to shake the can more or less vigorously. 
     This necessary shaking phase is obviously a burden on the production process for finished products using the so-called tinting systems as it leads to additional manual labor—often difficult due to the size and weight of the cans—or the use of specialized mixing machines, thereby increasing system costs. In any case, however, mixing also considerably increases the production time of finished products. 
     Thus, at the state of the art today, the homogenization stage is on the bottleneck in terms of the productivity of a rapid dispensing machine, and in any case limits the use of tinting systems to products with good fluidity, and does not allow the use of highly viscous products of those containing large amounts of solid or plastic particles. 
     SUMMARY OF THE INVENTION 
     The purpose of the present invention is to resolve the above difficulties, in particular to provide a dispensing machine of the type indicated in the preamble of the present description that allows metered delivery and continuous homogenization of finished painting products. The primary object of the invention is to obtain a finished, colored painting product at the machine outlet that does not require any further blending. 
     Another purpose of the present invention is to eliminate the mixing machines traditionally combined with dispensing machines to increase the productivity of a tinting system. 
     A further purpose of the invention is to integrate and automate the various production phases of finished paint products, expanding the range of component products that may be used in a tinting system. 
     A further purpose of the invention is to integrate and automate the various production phases of finished paint products, expanding the range of component products that may be used in a tinting system. 
     In order to achieve the above objects, the invention regards a dispensing machine of the type indicate in the preamble to this description, with the features set forth in the attached claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Additional features and advantages shall become apparent from the following description of one preferred embodiment, with reference to the enclosed figures, provided solely as non-limiting examples, wherein: 
     FIG. 1 is a schematic plan view of a dispensing machine built according to the invention, from which the upper covering panels have been removed for clarity, 
     FIG. 2 is a plan view of the dispensing unit of the machine in FIG. 1, 
     FIG. 3 is a longitudinal cross-section of the dispensing unit according to line III—III in FIG. 2, 
     FIG. 4 is an enlarged plan view of the dispensing head in FIG. 2, 
     FIG. 5 is a longitudinal cross-section of the dispensing head according to line V—V in FIG. 4, and 
     FIG. 6 is a diagram of the washing system of the dispensing head in FIGS.  4  and  5 . 
    
    
     DETAILED DESCRIPTION 
     With reference now to the figures, reference number  1  indicates generally a dispensing machine comprising multiple motor pump units  2 , preferably housed in modular frames  3 , to allow the machine to be easily expanded according to the number and variety of component products to be dispensed. Each motor pump unit includes a motor  4 , preferably but not limitatively a brushless electric motor, whose operation is controlled independently from that of the motors of the other motor pump units by means of a control circuit of known type, preferably interfaced with a computer. In particular, the control circuits regulate the rotation speed of the motors  4 , each of which is connected to the shaft of a corresponding positive-displacement pump  5  provided with inlet openings  6  and outlet openings  7 . The inlet openings  6  are connected to reservoirs (not shown in the figure) of component products-bases, colorants, various types of additives, etc. The outlet openings are instead connected to distribution lines  10  (the path of which is shown by the dashed line in FIGS.  2  and  3 ), with the interposition of three-way, two-position recirculation valves  11   a,    11   b,  from which the recirculation lines also branch out to return the component products to their respective reservoirs. The distribution lines  10  are conveyed to a dispensing unit  8 , located in the upper portion of a central dispensing module  9 , which also preferably contains the control electronics of the motor pump units  2  and the recirculation valves  11   a,    11   b  associated with each reservoirs, as well as the computer. 
     As can be seen more clearly in FIGS. 2 and 3, the ends of the distribution lines  10  are closed by valve devices  12 , preferably pin valves, which may open selectively to connect the distribution lines  10  to an axial bore  13   a  of a dispensing head  13 , which opens to the outside through a dispensing nozzle  13   b.  A mixing device, for example a turbine  20 , rotating around a substantially vertical axis Z—Z, is mounted inside the dispensing head  13 . In particular, although not limitatively, the turbine  20  is attached to one end of a rotating shaft  14 , a wheel or pulley  15  being keyed to the other end thereof which extends above the dispensing unit  8 . The pulley  15  is connected to a pulley or drive wheel  17 , attached to the shaft of a mixing motor  18 , by means of a belt or chain  16 . It is obviously possible to adopt different but functionally similar construction systems to transmit motion from the motor  18  to the mixing device  20 , such as for example a gear transmission, a universal joint, or other functionally similar system. 
     FIGS. 2 and 3 show a sample configuration of the dispensing unit  8  of a dispensing machine adapted to dispense up to sixteen different bases and sixteen different colorants. The three-way valves  11   a,  which provide selective dispensing of bases or their recirculation to the corresponding reservoirs, are arranged in a semicircle around the dispensing head  13 . 
     The three-way valves  11   b,  smaller because they are used to selectively dispense colorants, are arranged in arcs on both sides of the motor  18 . The pin valves  12 , one for each three-way valve  11   a,    11   b,  are arranged in a circle around the dispensing head  13 . To keep the system compact, in the configuration shown the pin valves  12  are stacked vertically in pairs, as can be clearly seen in FIGS. 3 and 5. 
     As can be more clearly seen in FIGS. 4 and 5, the pin valves  12  are mounted on a ring support  40 , wherein radial ducts  41  are provided in which the pins  42  of the valves  12  can move axially, selectively controlled by actuators  43 . Each radial duct  42  communicates with a corresponding inlet opening  44 , to which a corresponding line  10  is connected as it arrives from the three-way valves  11   a,    11   b.  The radial ducts  41  open into one or more shared chambers  45  which, in turn, communicates with the axial bore  13   a  of the dispensing head  13 , upstream from the turbine  20 . 
     Between dispensing a finished product having a certain formula and the next product, having a different formula, it is necessary to clean the shared nozzle  13  and the turbine  20 . To this end, the machine  1  comprises a washing unit  21  illustrated schematically in FIG.  6 . 
     The washing unit  21  comprises a pressure regulator  22 , through which compressed air from a pneumatic infeed circuit  25  is delivered. The compressed air is sent through a non-return valve  23  to a tank  24  containing a solvent suited to the type of colorant products and bases used. The solvent is added to the tank  24  through a cap  26 , after deactivating or closing the pneumatic infeed circuit  25 . A safety valve  27  ensures that the pressure in the tank does not exceed a desired preset level. An outlet duct  28  connects the tank  24  to a manifold  30 , from which in turn leads a washing duct  29  that opens into the dispensing head  13 , upstream from the turbine  20 . Along the outlet duct  28  there are interposed a filter  31  and a solvent washing solenoid valve  32  that selectively enables entry of the solvent into the dispensing nozzle  13 . 
     The compressed air coming from the pneumatic infeed circuit  25  is also used to feed the solenoid valves  11   a,    11   b  through the ducts  47 , after passing through a second pressure regulator  33 . The air outlet duct from the second regulator  33  also communicates with the manifold  30 , with the interposition of an air washing solenoid valve  34 . A discharge duct  35  is also connected to the manifold  30 , and is selectively closed by a discharge solenoid valve  36 . 
     During operation of the dispensing machine  1 , a predetermined formula defining the proportions of components products to make up a certain finished product is, for example, selected or entered by the user via the computer. A consent command enables transmission of data from the computer to the control systems of the motor pump units  2 , which regulate the speed of the motors  4  and thus the flow rate of the pumps  5 . Until the speed and throughput of all of the pumps  5  involved in the formula has stabilized, the solenoid valves  11   a,    11   b  are kept in the recirculation position. When a steady condition is reached, the recirculation valves  11   a,    11   b  and the pin valves  12  for the products required by the formula, generally comprising a base and one or more colorants, are opened simultaneously to convey said ingredients to the dispensing unit  8 . The component products enter the chambers  45 , then move into the dispensing head  13  in predetermined proportions in terms of amount per unit of time. The products are then immediately blended by the mixing turbine  20  powered by the motor  18 , which may be run at constant or variable speed depending on the component products, so as to provide the turbine  20  with a preferably high speed, sufficient to blend the component products perfectly. Thus the finished product arrives at the outlet of the dispensing nozzle  13   b,  and only needs to be packaged in the desired containers. 
     The automatic washing unit  21  of the dispensing head  13  is activated upon a command sent by the computer at each formula change. The washing cycle takes place with the solenoid valves  11   a,    11   b  in recirculation position, with all pin valves  12  closed, with the discharge solenoid valve  36  and air washing solenoid valve  34  closed, and with the turbine  20  activated. The solvent washing solenoid valve  32  opens to allow solvent to enter the dispensing head  13 , upstream from the turbine  20 . The solvent delivery phase lasts long enough to allow complete and thorough washing of the chambers  45 , the dispensing head  13  and the mixing turbine  20 . When this phase is complete by closing the solvent washing solenoid valve  32 , a new phase begins in which air enters thanks to the opening of the air washing solenoid valve  34 . This phase removes any residual solvent remaining inside the dispensing head  13  and in contact with the turbine  20 . The washing cycle is completed by switching the air solenoid valve  34  to the closed position and by opening the discharge solenoid valve  36 . This discharge valve  36  is also kept open while fluid products are dispensed, to avoid surge pressures in the dispensing nozzle. To better understand the operating principle of the dispensing machine described above in one particular embodiment, a specific example of dispensing with details regarding machine parts, which must not be construed as restrictive in any way, is hereinbelow described. 
     EXAMPLE 1 
     Pumps  5  have been selected having different specifications for dispensing bases and colorants. 
     For colorants, the pumps have a flow rate of 3 ml of product per revolution, and can achieve a maximum rotation speed of 150 rpm. For the bases, the pumps have a flow rate of 25 ml per revolution, and a maximum speed of 150 rpm. 
     Let us assume we wish to produce a finished paint product having a simple formula, in which a base B is diluted by 1% of its volume with a colorant C. The finished product, having a known specific weight, should have a total weight corresponding to a volume of 1010 CC. 
     To produce the desired amount of product in the shortest possible time, the base pump B is set up to rotate at its maximum speed of 150 rpm, corresponding to a flow rate of 62.5 ml/s of base product. The time needed to dose 1000 cc of base product is therefore 16 seconds. The central computer thus calculates the flow rate of colorant C needed to dispense 10 cc in 16 seconds, so that the proportion between the base and colorant entering the dispensing nozzle is constant over time. Given the displacement of the colorant pump, the computer system calculates that the corresponding motor must run at a speed of 12.5 rpm. This information is sent to the control system of the motor  4 , which brings the circulation flow in the recirculation circuit to the required cycle speed. 
     The two products involved in the formula, base B and colorant C, are thus sent to the dispensing head  13  and mixing device  20  at the above rates. 
     Within 16 seconds, the dispensing nozzle  13   b  releases the required amount of finished product, already dosed and blended. 
     The machine according to this invention may be built with fluid product reservoirs mounted directly on the machine, or located in adjacent modules, or may have only the central structure  9  containing the distribution unit and a set of inlet openings to which one may connect fluid feed lines from external or remote reservoirs via generally know means, such as through a screw coupling or quick fitting. 
     Naturally, the principle of the invention remaining the same, the embodiments and development details may vary widely from those described and illustrated without exceeding the extent of the present invention.