Abstract:
An apparatus for metering a plurality of different liquid or pasty masses to a receiving container including: 
     first support for supporting containers for the masses in fixed positions; 
     a fixedly disposed annular frame bearing a number of dispensing nozzles controllable by a fixedly disposed control device and each individually connectable to said containers via respective conduits; 
     a second support controllable by the control device for supporting a receiving container such that this receiving container is displaceable in an annular path corresponding with the annular form of the frame and can be placed temporarily beneath a chosen dispensing nozzle for receiving mass dispensed by this dispensing nozzle; 
     a weighing device on which a receiving container can be placed, which weighing device can supply weight signals to the control device; 
     wherein the weighing device is disposed fixedly and supports the second support.

Description:
BACKGROUND OF THE INVENTION 
     FIELD OF THE INVENTION 
     The invention relates to an apparatus for metering a plurality of different liquid or pasty masses. Such an apparatus is known in diverse embodiments and is also designated as colour kitchen. Said masses are in that case paint, ink, thickening or thinning agents and the like. The masses have to be supplied in predetermined quantities, at least mutual ratios, to a receiving container. This receiving container, for instance a bucket, a can or the like, must be filled with a determined quantity of mixture. For this purpose predetermined quantities of selected masses are admitted successively into the receiving container. As soon as the receiving container is filled with all desired components in the desired quantities, a subsequent receiving container is filled in comparable manner with the constituent components. In this subsequent and other cycles the composition can differ in accordance with the composition of the finally required mixture. 
     After the constituent components have been placed in the receiving container, homogenization generally takes place by means of known homogenizing processes, in particular stirring and shaking. 
     An apparatus of said type comprises provisions for supporting containers for the masses for metering. These containers can be connected by means of flexible hoses or fixed conduits to dispensing nozzles for individual dosing in each case of a determined quantity of a relevant mass. A placed receiving container and all relevant dispensing nozzles must be mutually movable such that each dispensing nozzle can dispense mass to the receiving container. It is known for instances to fixedly dispose a container on scales and to place the relevant dispensing nozzle in each case above the receiving container by means of a movable frame. 
     Alternatively, a frame supporting the dispensing nozzles can be fixedly disposed, wherein the scales supporting the receiving container are movable thereunder. 
     The scales are of importance for dispensing a determined mass in the correct quantity. The control of the dispensing nozzles therefore takes place on the basis of this mass measurement. It is possible in principle to suffice with a mass or weight difference measurement. 
     In the case where the dispensing nozzles are movable relative to the storage container, use must be made of flexible conduits. The great drawback of flexible conduits is that they are subject to undesirable mechanical loads, in particular torsion, which can greatly reduce the lifespan and can cause malfunctions. Hoses are further subject to ageing. This is the reason why an embodiment is usually recommended with a fixed spatial relation between the dispensing nozzles and the storage containers, in which case fixed conduits of for instance plastic or metal can be used. In that case the scales with a receiving container thereon must be arranged displaceably relative to the nozzles. Such an arrangement does however have the drawback that the conduits connecting the electronically operating weighing device to central, fixedly disposed control means are likewise subjected to mechanical influences. 
     This mechanical influence can remain limited by making use of a horizontal linear x or XY mobility within limited boundaries. Such an arrangement has the drawback however that it takes a relatively large amount of time to go from one side of an array to the other, which may nevertheless occur during operation of the apparatus. Recommended in this respect is an annular arrangement of the dispensing nozzles and a corresponding annular path in which the weighing device with a receiving container thereon can move. 
     If desired, there may even be a movement predominantly in one direction along such a path. This is not possible however without specific measures, since the conduits providing the necessary supply of electrical energy to the weighing device and the information cables are otherwise placed under torsional stress. 
     It is an object of the invention to provide an apparatus which obviates all drawbacks of said techniques and is not afflicted with the limitations of the known art. 
     SUMMARY OF THE INVENTION 
     In respect of the above, the invention provides an apparatus for metering a plurality of different liquid or pasty masses such as paint, ink, thickening or thinning agents and the like to a receiving container, for instance a bucket or a can, which apparatus may include: 
     first supporting means for supporting containers for the masses in fixed positions; 
     a fixedly disposed annular frame bearing a number of dispensing nozzles controllable by fixedly disposed central control means (PLC, PC) and each individually connectable to said containers via respective conduits; 
     second supporting means controllable by said control means for supporting a receiving container such that this receiving container is displaceable in an annular path corresponding with the annular form of the frame and can be placed temporarily beneath a chosen dispensing nozzle for receiving mass dispensed by this dispensing nozzle; 
     a weighing device on which a receiving container can be placed, which weighing device can supply signals to the control means which are representative for the weight of the receiving container with its content or the change in that weight; 
     which control means are adjustable, for instance by means of program control, for dispensing different masses in determined quantities to successive receiving containers, for instance in successive cycles, in order to make successive mixtures of respective chosen compositions; 
     wherein the weighing device is disposed fixedly, is connected to the control means via cable means and supports the second supporting means, and 
     wherein the second supporting means are rotatably drivable round a vertical axis by means of a drive device co-acting with the second supporting means such that when a weighing is performed the drive is inactive such that no forces which can influence the weighing are exerted on these second supporting means, for instance the drive is substantially disengaged from the second supporting means. 
     Attention is drawn in this respect to the fact that an apparatus is known from applicant&#39;s earlier non-prepublished Netherlands patent application NL-1006685 of Jul. 30, 1997 wherein the weighing device is supported by the second supporting means. Since the weighing device herein rotates, special provisions are necessary to prevent unintended torsion of the cable means which connect the weighing device to central control means. Since the weighing device is disposed fixedly in the apparatus according to the present invention, there is no question of cables subject to torsion. 
     The structure according to the present invention is therefore simpler than that according to the above stated Netherlands patent application. The apparatus is suitable for metering liquid or pasty masses into relatively small containers. The structure according to the invention prevents any vertical force being exerted by the drive means on the scales. Such a vertical force must be avoided since it would influence the measurement accuracy. 
     Driving takes place in the horizontal plane, wherein the input and the output parts of the drive element lie mutually in line. 
     A specific embodiment of the apparatus according to the invention has the special feature that the drive comprises at least one drive cylinder of pneumatic, hydraulic or electrical type. 
     A specific embodiment has the special feature that the drive comprises at least two cylinders connected mechanically in series to each other, the respective strokes of which correspond with respectively ½, ¼, ⅛, etc. of the periphery of the drive drum. This embodiment enables rapid adjustment of the angular position of the second supporting means through respectively±180°, ±90°, ±45°, etc. It will be apparent that any discrete angular position can hereby be realized, while the resolution is determined by the cylinder with the smallest stroke. 
     The invention will now be the elucidated with reference to the annexed drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a partly broken away top view of an apparatus according to NL-1006685 such that a part of the interior is visible; 
     FIG. 2 shows a partly broken away front view of the apparatus of FIG. 1; 
     FIG. 3 shows a partly broken away side view of the apparatus of FIG. 1; 
     FIG. 4 shows the detail IV in FIG. 1 on enlarged scale; 
     FIG. 5 shows the top view according to FIG. 4 of the total arrangement of all dispensing nozzles; 
     FIG. 6 is a schematic representation of an embodiment with fixed orientation relative to the centre of the path; 
     FIG. 6A shows a cross-section through the central transmission device with slide contacts; 
     FIG. 6B shows a view corresponding with FIG. 6A of capacitive optical transmission; 
     FIG. 6C shows a schematic view corresponding with FIG. 6A of an inductive transmission; 
     FIG. 7 shows an embodiment with fixed orientation relative to a fixed point outside the circular path; 
     FIG. 8 is a schematic representation of an embodiment with invariable orientation making use of mechanical XY guide means; 
     FIG. 9 shows a variant with toothed wheels and a chain or toothed belt; 
     FIG. 10 shows a variant with toothed wheels; 
     FIG. 11 a  shows a schematic side view of an apparatus according to the invention; 
     FIG. 11 b  shows a highly schematic top view of the detail A—A in FIG.  11 . 
     FIG. 12 is a partly transparent perspective view of another embodiment of the invention; and 
     FIG. 13 is a schematic side view of yet another embodiment of the invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIGS. 1,  2  and  3  show an apparatus  1  for metering liquid or pasty masses to a receiving container  2 ; on top of the apparatus  1  containers for the masses can be placed in fixed positions on a support platform  3 . 
     The apparatus further comprises a fixedly disposed frame  4  which bears a number of dispensing nozzles controllable by fixedly disposed central control means  100  such as a PC or PLC. These nozzles are ordered in a respective inner ring  5  and outer ring  6 . Inner ring  5  comprises eleven dispensing nozzles, all designated with  7 , while outer ring  6  comprises twenty-two dispensing nozzles  8 . It is noted that each dispensing nozzle is connected to two conduits, i.e., a supply conduit and a return conduit. It is generally known and usual that mass flows permanently through dispensing nozzles of this so as not to incur any problems with fouling, caking and lump-forming in the case of prolonged standstill. The dispensing openings are shown particularly clear in FIGS. 4 and 5 as the central zones of the relatively large annular structures. 
     The apparatus  1  further comprises second supporting means in the form of a rotatable support platform  9  which bears a weighing device  10 . With this configuration receiving container  2  can proceed through a path such that it can receive mass from any of the dispensing nozzles  7 ,  8  of both the inner ring  5  and the outer ring  6 . 
     The weighing device is connected to a power source and the control means  100  for receiving power supply and for generating information to the control means  100 . This connection is embodied such that the cable means required for this purpose are not subjected to any torsion in this embodiment, irrespective of the angular position of support platform  9 . This important aspect of the invention will be further elucidated with reference of FIG.  6 . 
     Support platform  9  is rotatable by means of a motor  12  with transmission means  13  connected thereto. Within the scope of the invention it is not necessary to discuss the manner in which the control of the motor and optional transmission means takes place such that receiving container  2  is always carried to the correct location and is held still there. Tacho means can for instance co-act with support platform  9 . 
     Not considered at all is the manner in which dispensing nozzles  7 ,  8  are controlled. It is generally known that use can be made for this purpose of electrically, pneumatically or hydraulically controllable valves. This aspect does not however form part of the invention. 
     FIG. 6 shows the annular path  14  in which weighing device  10  can move as according to arrows  16 . Owing to the fixed arrangement of weighing device  10  on support platform  9 , it has a fixed orientation relative to the centre  15  of the path  14 . Designated symbolically are two cables  17 , which connect weighing device  10  to respective split rings  18  and  19  via respective slide contacts  20  and  21 . 
     FIG. 6A shows the relevant configuration. 
     FIG. 6B shows an alternative. In this embodiment there are two possibilities. A lower structure  22  and an upper structure  23  mutually co-act for the electrical transfer of energy and signals. In a practical embodiment the lower structure, which is fixedly disposed, comprises an outer ring  24  and an inner ring  25 , while the upper structure has rings co-acting therewith, i.e. an outer ring  26  and an inner ring  27 . The upper structure is connected to support platform  9  and therefore are rotatably movable. Rings  24 ,  25 ,  26 ,  27  can be pairs of capacitor plates co-acting for capacitive transfer, particularly while making use of high frequencies. Use can also be made of light-emitting junctions or semiconductor diodes and light-sensitive receptors co-acting therewith. It is also possible to transfer energy as well as analog or digital information with such structures. 
     FIG. 6C shows a lower structure  28  and an upper structure  29  which comprise respective, mutually co-acting annular coils for inductive transfer of power supply, for instance with a frequency of 10 kHz and the transfer in reverse direction of information, for instance information with a frequency content considerably above said power supply frequency. 
     FIG. 7 shows an embodiment wherein a symbolically designated arm  30  of variable length, for instance an arm consisting of telescopically co-acting parts, is connected non-rotatingly on one side to weighing device  10  and connected pivotally on the other side to a hinge  31 . The structure shown in FIG. 7 ensures that the net rotation of weighing device  10  amounts to zero after covering a path of 360°. 
     FIG. 8 shows a variant wherein via an arm  32  of variable length the weighing device  10  is movable with fixed orientation relative to a carriage  33 , which is movable reciprocally as according to arrow  35  along a straight guide  34 . With this configuration, as shown in FIG. 8, the orientation of weighing device  10  is kept invariable and independent of the position on the path  14  of weighing device  10 . 
     FIGS. 9 and 10 show variants which realize the same effect with other means. 
     In the embodiment according to FIG. 9, weighing device  10  is supported by a first toothed wheel  35  which is rotatable relative to path  14  and which co-acts via a toothed belt or chain  36  with a fixedly disposed central second toothed wheel  37 . Toothed wheels  35  and  37  are identical. The orientation of weighing device  10  is thus kept invariable over the whole path  14 . 
     The configuration of FIG. 10 differs from the configuration of FIG. 9 insofar as toothed wheels  35  and  37  are not mutually coupled with a toothed belt or chain  36  but via a third toothed wheel  38  which is disposed such that the centres of toothed wheels  35 ,  38 ,  37  always lie on a collective radial straight line. FIG. 10 shows symbolically that the dimensions of toothed wheel  38  are irrelevant. Of essential importance however is that toothed wheels  37  and  35  are identical. 
     It is noted that transmission means other than those according to FIGS. 9 and 10 are also possible so as to ensure that the orientation of weighing device  10  is invariable. 
     FIGS. 1-10 all relate to the apparatus according to NL-1006685. FIGS. 11 a  and  11   b  relate to the structure according to the present invention. Reference is made to FIGS. 1,  2 ,  3 ,  4  and  5  for elucidation of the deployment of the dispensing nozzles. 
     FIG. 11 a  shows an apparatus  51  according to the invention. At variance with the embodiments of FIGS. 1-10, the weighing device is disposed fixedly in apparatus  51 . It supports a platform  52  which is rotatably drivable via a vertical rotation axis  53 . For this purpose platform  52  is rigidly coupled to a drive drum  54 . This is mounted for rotation round axis  53 , for instance by a central pin, optionally in combination with further bearings. 
     As shown in FIG. 11 b,  a tensioned cord  55  is trained around drive drum  54  such that the one part  56  and the other part  57  of drive element  55  (e.g., cord) lie precisely in line with each other. Tensile forces can be exerted in both directions on drive element  55  by dirve means to be described herein below. These forces are indicated with arrows  58 . Cord  55  is of the endless type and, as is drawn in the embodiment of FIG. 11 a,  is guided in an endless path by four deflecting rollers  59 ,  60 ,  61 ,  62 . Driving takes place via a drive device comprising three cylinders  63 ,  64 ,  65 , respectively. These have respectively a stroke of ½, ¼, and ⅛ of the periphery of the drive drum  54 . Since the cylinders are mutually connected in series and individually controllable via the control means  100 , platform  52  can be placed by suitable control of cylinders  63 ,  63 ,  65  in any discrete angular position with mutual distances of 45°. 
     FIG. 12 shows a weighing device  10  with a weighing platform  72  supported rotatably by central shaft  71 . Weighing platform  72  bears on its periphery a toothing  73  and thus has the character of a toothed wheel. Co-acting with this weighing platform or toothed wheel  72  is a drive toothed wheel  74  which can be driven by a motor  75 , for instance a stepping motor, which is disposed fixedly relative to weighing device  10 . When a weighing is performed, wherein one or more containers are placed on weighing platform  72 , the driving co-action between toothed wheels  74  and  72  must be prevented from having any effect on the weighing. Toothed wheel or weighing platform  72  must be substantially freely movable in vertical direction in order to carry out weighing. Drive toothed wheel  74  could have a disruptive influence here. In this respect the metering device is embodied in the embodiment according to FIG. 12 such that during performing of a weighing the drive  74 ,  75  is inactive and toothed wheels  72 ,  74  are mutually disengaged. In this way, no force which may influence the weighing can be exerted on weighing platform  72 . Attention is drawn to the fact that with a view to a complete disengagement the teeth  73  of weighing platform  72  and the teeth  76  of toothed wheel  74  fit together with a slight gap. Hereby achieved in addition to driving operation of motor  75  is that the freely rotatable weighing platform  72  can be moved freely up and downward during a weighing. 
     The problem described occurs in the case of FIG. 12 when the motor and the weighing device  10  are fixedly disposed relative to each other. 
     FIG. 13 shows another solution in this respect. In the configuration of FIG. 13 weighing device  10  bears a weighing platform  72  deployed solely for vertical displacement. This weighing platform  72  supports a directly driven motor  82  which, via a drive shaft  83 , supports a rotatable support platform  84  on which containers  2  can be placed. In the embodiment according to FIG. 13 weighing platform  81  also supports the motor  82  which provides the rotation of support platform  84 . The motor  82  and drive shaft  83  comprise a drive device of the apparatus  1 . The signal processing means which process the signals generated by weighing device  10  must be embodied such that a correction can take place for the presence of a motor  82  which is also weighed by weighing device  10 . As is usual during a weighing, the scales inclusive of the supporting means are set to zero value, which zero value in the case of FIG. 13 also takes account of the weight of the motor. 
     In FIGS. 11,  12 , and  13  an arrow  91  indicates the rotation of the respective support platforms. 
     It is noted that the variant according to FIG. 13, wherein motor  82  is supported by weighing platform  81 , can also drive support platform  84  in the manner shown in FIG. 12, therefore not directly but via a toothed geared. In the case the toothed gearing does not then have to be embodied such that during weighing the toothed wheels are mutually disengaged. Because weighing platform  81  supports both the motor and the support platform, both move up and downward together, so that there is no need to fear a force being exerted on the support platform by the motor such that the measurement could thereby be influenced.