FLUID DISPENSING APPARATUS AND METHOD OF OPERATION THEREOF

Abstract: Apparatus for dispensing a desired quantity by weight of a fluid material such as a liquid base colour printing ink for shade mixing purposes is provided, which apparatus includes a container (1) for the fluid material to be dispensed, a main fluid material dispensing discharge outlet means (2) on the container (1), a secondary fluid material dispensing discharge outlet means (3) on the container (1), which secondary fluid material dispensing discharge outlet means (3) is adjustably operable to dispense a particular volume of fluid material corresponding to a particular weight of fluid material to be dispensed, and means (4) for applying pressure to fluid material when in the container to (1) urge it towards both said outlet means (2, 3), the arrangement being such that to dispense a desired weight of a fluid material over a certain weight from the apparatus into a receptacle therebelow on a weighing scale, the means (4) for applying pressure to the fluid material in the container (1) is operated to urge the fluid material in the container (1) towards the main and secondary outlet means (2, 3), the main and secondary outlet means (2, 3) are actuated, fluid material is dispensed from both the outlet means into the receptacle, the main outlet means (2) is closed when a predetermined major weight of fluid material has been dispensed, below the desired weight, into the receptacle, the secondary outlet means (3) is shut-off when a predetermined secondary weight of fluid material has been added to the predetermined main weight of fluid material in the receptacle to bring the weight of the dispensed material in the receptacle closer to and below the desired weight, the dispensed fluid material in the receptacle is weighed to give an actual weight value, the weight difference between the desired weight and the actual weight is calculated, the secondary outlet means (3) is actuated to dispense the weight difference into the receptacle, and the final weight of dispensed fluid material in the receptacle is weighed for checking purposes, and the arrangement being such that to dispense a desired weight of fluid material below a certain weight from the apparatus into a receptacle therebelow on a weighting scale, the means (4) for applying pressure to the fluid material in the container is operated to urge the fluid material in the container (1) towards the main and secondary outlet means (2, 3), the secondary outlet means (3) only is actuated to dispense fluid medium therefrom into the receptacle until a predetermined weight of fluid material below the desired weight has been dispensed and then shut-off, the dispensed fluid material in the receptacle is weighed to give an actual weight value, the weight difference between the desired weight and the actual weight is calculated, the secondary outlet means (3) is actuated to dispense the weight difference into the receptacle and the final weight of dispensed fluid material in the receptacle is weighed for checking purposes.

Description: This invention relates to an apparatus for dispensing a desired weight of fluid material such as coloured liquid printing ink, for example according to the quantity of the coloured ink required to be mixed with measured quantities of other coloured printing inks for ink constituents to make up a desired colour ink mix, and to a method of dispensing a desired weight of such fluid material. Known printing ink colour mixing methods generally involve colour matching the required shade and presenting the desired shade in terms of a 100 part mixing formula by weight of different base colour inks, dispensing the required amounts of the selected base colour inks to the mixing formula requirements to give the desired total weight of the finished shade ink, and mixing the dispensed base colour inks. Provided that the correct 100 part mixing formula is selected, the basic problem in achieving the desired shade ink is in dispensing and mixing correct quantities of the base colour inks called for by the 100 part mixing formula. Conventional dispensing techniques and apparatus which dispense the base colour inks by volume or by weight are not sufficiently accurate for mixing printing inks for tinplate printing where the base colour inks may be particularly viscous and vary considerably in specific gravity from one colour to another due to the different weight pigments employed. Additionally such conventional dispensing techniques and apparatus can be quite slow in operation again due to the ink viscosity and need for accurate dispensing of a desired quantity. There is thus a need for a generally improved apparatus for dispensing a fluid material such as a liquid printing ink and for a generally improved dispensing method for dispensing desired quantities of fluid component materials of a mixture such as liquid base colour printing inks to the desired quantities called for by a particular colour shade formula. According to one aspect of the present invention there is provided a method of dispensing a desired weight of fluid into a receptacle, including: (a) positioning a fluid material container provided with a main fluid material discharge outlet means and a secondary fluid material discharge outlet means above the receptacle which is provided on a weighing scale for weighing the receptacle; (b) applying pressure to the material in the container to urge the material towards the main and secondary outlet means; (c) selectively actuating either the main and secondary outlet means together when a desired final weight of material to be dispensed is over a predetermined threshold value, or the secondary outlet means alone when the desired final weight of material to be dispensed is less than the threshold value; (d) then shutting-off the main outlet means, if actuated, when the weight of dispensed material is approximately a primary predetermined amount less than the desired final weight; (e) then shutting-off the secondary outlet means when the weight of dispensed material is approximately a secondary predetermined amount less than the desired final weight; (f) then determining the actual weight of the dispensed material in the receptacle; (g) then calculating the weight difference between the desired final weight and the determined actual weight; (h) then actuating the secondary outlet means to dispense a weight of material into the receptacle equal to the calculated weight difference; and (i) then checking the actual final weight of the dispensed material in the receptacle. According to another aspect of the present invention, there is provided an apparatus for dispensing a desired weight of a fluid material, comprising: a container for the fluid material to be dispensed; a main fluid material discharge outlet means on the container and actuable to dispense material from the container; a secondary fluid material discharge outlet means on the container and actuable to dispense material from the container; means for applying pressure to the material in the container to urge the material towards the main and secondary outlet means; a receptacle for receiving material dispensed by the main and secondary outlet means; a weighing scale on which the receptacle is provided for weighing the receptacle; and control means operable: (a) to actuate selectively either the main and the secondary outlet means together when a desired final weight of material to be dispensed is over a predetermined threshold value, or the secondary outlet means alone when the desired final weight of material to be dispensed is less than the threshold value; (b) then to shut-off the main outlet means, if actuated, when the weight of dispensed material is approximately a primary predetermined amount less than the desired final weight; (c) then to shut-off the secondary outlet means when the weight of dispensed material is approximately a secondary predetermined amount less than the final weight; (d) then to read the weighing scale to determine the actual weight of the dispensed material in the receptacle; (e) then to calculate the weight difference between the desired final weight and the determined actual weight; (f) then to actuate the secondary outlet means to dispense a weight of material into the receptacle equal to the calculated weight difference; and (g) then to read the weighing scale to check the actual final weight of material dispensed in the receptacle. Preferably, such an apparatus is one of a plurality of such apparatus, with the receptacle, weighing scale and control means being common to the plurality of apparatus, the containers being movable relative to one another selectively to bring the outlet means of the containers in turn into registry with the receptacle, and the control means being operable to cause material to be dispensed in turn from the containers in accordance with a stored 100 part by weight formula. Other preferred features of the invention will be apparent from the accompanying dependent claims and the following specific description. Reference is directed to patent application GB-A-2151362, which describes a dispensing head for dispensing metered quantities of different liquid media into a single receptacle from respective containers each having a respective pair of dispensing valves associated therewith. The valves of each pair are for coarse (or fast) flow and fine (or slow) flow respectively. From each container, the liquid is drawn through a single outlet by a single pump before branching to the dispensing valves of the respective pair. Also, GB-A-2151362 does not disclose the application of pressure to the material in the container. For a better understanding of the present invention, and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which: Figure 1 is a diagramatic perspective view from above of a fluid material dispensing apparatus according to a first embodiment of the invention, Figure 2 is a vertically sectioned view of a top portion of the apparatus of Figure 1 taken along the line A-A in Figure 1, but to an enlarged scale, Figure 3 is a partial vertically sectioned view to an enlarged scale of the bottom part of the dispensing apparatus of Figure 1 taken along the line A-A thereof, again to an enlarged scale, Figure 4 is a view from below of the apparatus of Figures 1,2 and 3 taken in the direction of the arrow B in Figure 1, to the same scale as Figures 2 and 3, Figure 5 is a side view of the top portion of the apparatus of Figures 1 to 4 taken in the direction of the arrow C as shown in Figure 2, and Figure 6 is an end view of the bottom portion of the apparatus of Figures 1 to 5, taken in the direction of the arrow D as shown in Figure 3. A fluid dispensing apparatus according to one embodiment of the present invention has been illustrated, for convenience, in terms of an example of the apparatus suitable for dispensing a measured quantity of a coloured liquid printing ink by weight according to the quantity of the coloured ink required to be mixed with measured quantities of other colour printing inks or ink constituents to make up the desired colour ink mix according to the requirements of a one hundred part by weight mixing formula for the desired colour shade. Such a dispensing apparatus basically includes a container 1 for the fluid materials such as ink to be dispersed, a main fluid material dispersing discharge outlet means generally indicated at 2 on the container 1, a secondary fluid material dispensing discharge outlet means generally indicated at 3 on the container 1 and means generally indicated at 4 for applying pressure to fluid material when in the container 1 to urge it towards both said outlet means 2 and 3. The secondary means 3 is adjustably operable to dispense a particular volume of fluid materials such as liquid ink corresponding to a particular weight of ink to be dispensed. To this end the means 3 preferably includes a gear pump 5 of the kind having a drivable rotatable toothed rotor member and meshing idler gear (not shown) contained in a housing chamber in fluid communication at an inlet side 5a of the rotor member and gear with the container 1 and at the outlet side 5b of the rotor member and gear with an outlet nozzle assembly generally indicated at 6 in Figure 3, of the outlet means 3. The secondary outlet means 3 also includes a drive motor 7 operable to rotate the rotor member of the gear pump 5 in steps each of which corresponds to a specific volume of liquid ink dispensed from the secondary outlet means 3. In this way any required weight of liquid ink can be dispensed by rotation of the rotor member of the gear pump 5 by the number of steps equivalent to the desired weight of ink to be dispensed. The weight of a particular fluid material to be dispensed in a rotor member step movement can be previously ascertained by weighing for the particular fluid material being dispensed. In other words, as different colour liquid inks may have different specific gravity and weight characteristics depending on their individual makeup it is possible, with the secondary outlet means 3 of this invention effectively to calibrate the gear pump 5 so that the weight of material dispensed per turn of the rotor member can be previously ascertained by actually rotating the rotor member by a predetermined number of steps of turns and weighing the amount of material dispensed for this movement. As the characteristics of the particularly liquid ink will be constant this value can be used for all dispensing operations from the container 1 containing that particular ink. If, in a subsequent operation of the apparatus of the invention, a different fluid material or liquid ink is placed in the container 1 a similar calibration operation can be carried out for that particular ink giving a different ink weight dispensed for the same number of turns or steps movements of the rotor member of the gear pump 5. In this way it is possible to dispense accurately desired fine weights of fluid material such as a liquid ink with the apparatus of the invention and easily to correct operation of the apparatus for different inks with different flow, weight and specific gravity characteristics. The outlet nozzle assembly 6 includes a substantially cylindrical nozzle member 8 as can be seen from Figure 3. The nozzle member 8 has a fluid flow passage 8a therethrough opening into a discharge aperture 9 through one end of the nozzle member 8. An external surface 10 at the discharge aperture end of the nozzle member 8 tapers towards the discharge aperture 9. The outlet nozzle assembly 6 also includes a housing member 11, conveniently in the form of an annular sleeve removably securable around the discharge aperture end of the nozzle member 8 at least around the tapered surface 10 thereof. Also forming part of the nozzle assembly 6 is an annular sheet-like membrane 12 made of any convenient flexible material such as plastics, metal or stiff rubber. This annular membrane 12 is secured around its outer edge to the housing member 11, conveniently by being recessed in a recess provided for this purpose in the outer end of the bore through the housing member 11 as illustrated in Figure 3. The manner of securing the member 12 to the housing member 11 and the manner of securing the housing member 11 to and around the nozzle member 8 are such that the inner edge 12a of the annular membrane 12 around its inner opening, lies closely adjacent to the tapered end surface 10 of the nozzle member 8 adjacent and around the discharge aperture 9 therethrough. In this way an annular gap is defined between the edge 12a of the annular membrane 12 and the tapered surface 10, which gap can be accurately controlled in dimensions by varying the longitudinal position of the housing member 11 relative to the nozzle member 8. The tapered external surface 10 of the nozzle member 8, surrounding housing member 11 and membrane 12 thereby define therebetween a substantially annular chamber 13 into which the gap between the inner edge 12a of the membrane 12 and tapered external surface 10 of the nozzle member 8, opens adjacent the discharge aperture 9. At a position radially remote from the discharge aperture 9 an inlet 14 opens into the chamber 13 through the external wall of the housing member 11. This inlet 14 can be put in communication with a source of gas under pressure, such as compressed air, so that the gas under pressure can be fed into the chamber 13 and from thence through the gap between the nozzle member tapered end surface 10 and inner edge 12a of the membrane 12 across the outer end of the discharge aperture 9 through the nozzle member 8 to blow away therefrom any fluid material such as liquid ink remaining thereon, for cleaning purposes. The main fluid material dispensing discharge outlet means 2 preferably includes an outlet passage 2a and a ball valve 15 selectively actuable to open or close the passage 2a to flow of fluid materials such as liquid ink therethrough from the container 1. As shown in the accompanying drawings, in the illustrated example of the apparatus of the invention, the container 1 is substantially cylindrical in shape having a closed base 16 at one end in and on which the main and secondary outlet means 2 and 3 are provided. The container 1 also includes an openable and closable lid 17 at its other end, which lid 17 preferably is hingedly connected as at 18 to the container 1. As illustrated the lid 17 need not completely close off the open upper end of the container 1 but may take the form of a bar hingedly connected at one end 18 to the container 1 and carrying a handle 19 at its opposite end. Releasable means such as turn screws 20 may be provided for releasably securing the lid 17 in place across the open upper end of the container 1. In the illustrated example where the lid 17 is in the form of a bar the means 4 for applying pressure to the fluid material such as liquid ink in the container 1 includes a presser plate 21 which is cylindrical in shape, and which in cooperation with the bar forming the lid 17 provides an end closure for the container 1. This presser plate 21 is slidably movable in the container 1 in sealed contact such as with an annular edge seal 22, as shown in figure 2, with the side walls 1a of the container 1. The presser plate 21 is operable to engage the upper surface, via intermediate sheet membrane (not illustrated) preferably made of paper, of the fluid material such as ink in the container 1, via the under surface 21a of the presser plate 21. To produce this movement of the presser plate 21 up and down in the container 1 the means 4 also includes a piston and cylinder assembly generally indicated at 23 operative to urge the presser plate 21 towards and away from the fluid material such as liquid ink in the container 1. The piston and cylinder assembly 23 includes a cylinder 24 fixably secured to the container lid 17 substantially perpendicularly thereto and substantially coaxially with the longitudinal axis through the container 1. The assembly 23 also includes a piston rod 25 slidably housed in the cylinder 24 and extensible therefrom. The piston rod is connected at its outermost end to the presser plate 21 in any convenient manner such as by passing through an aperture 26 through the centre of the presser plate 21 and being secured on the under surface 21a thereof to the presser plate 21 in any convenient manner such as by a nut 27. The piston rod 25 also is connected to the presser plate 21 coaxially with the longitudinal axis through the container 1 and extends substantially perpendicularly to the presser plate 21. The presser plate 21 may be provided with a guide rod 28 projecting therefrom substantially parallel to the piston rod 25 and projecting through an opening in the container lid 17. This guide rod 28 visually indicates the position of the presser plate 21 in the container 1 and hence the volume of fluid material remaining in the container. One convenient way of doing this is to provide a relieved face 28a part way along the guide rod 28 at a position approximating to the container 1 being half full of fluid material. Additionally a contact switch 29 may be provided associated with the guide rod 28 on the container lid 17 to indicate the position of the guide rod 28 corresponding to the half empty state of the container 1. Conveniently this is done by the switch 29 including a spring loaded roller 29a running on the side of the guide rod 28 so that when the roller 29a encounters the relieved face 28a of the guide rod 28 the subsequent longitudinal displacement under the force of the spring urging the roller 29a into contact with the periphery of the guide rod 28, actuates the switch 29 which can serve to trigger a warning indicator such as a light to draw attention to the state of the container 1 for replenishment purposes. Additionally the presser plate 21, as illustrated in Figures 1 and 2 incorporates an air-bleed valve 30 operative to bleed air from the container 1 from the fluid material side of the presser plate 21. The method of dispensing a desired quantity by weight of a fluid material such as a liquid base colour printing ink from shade mixing purposes from the apparatus of Figures 1 to 6 involves positioning the container 1 in which liquid ink to be dispensed is contained, above a receptacle (not shown) on a weighing scale (not shown). Then the presser plate 21 is urged towards the liquid ink in the container into contact therewith urging the ink towards the main and secondary outlet means 2 and 3 at the base of the container 1. Conveniently the container 1 is of a size sufficient to contain about 20 kilogrammes of liquid ink. If the amount of liquid ink to be dispensed is over a certain weight, such as over fifty grammes, the main and secondary outlet means 2 and 3 are both actuated together. Ink is dispensed from both outlet means 2 and 3 together into the receptacle on the weighing scale and when a predetermined major weight of ink, such as about ten grammes less than the final desired weight has been dispensed into the receptacle, the main outlet means 2 is closed by means of its ball valve 15. The secondary outlet means 3 is continued in operation until a predetermined secondary weight of liquid ink such as a further eight grammes, has been added to the predetermined main weight of ink in the receptacle, so bringing the weight of the dispensed material in the receptacle closer to and below the desired weight, such as within about two grammes of the desired weight. The secondary outlet means 3 is then shut-off by stopping rotation of the gear pump 5 via the motor 7 and the dispersed ink material in the receptacle on the weighing scales is weighed to give an actual weight value. The weight difference between the desired weight and the actual weight is calculated and the secondary outlet means 3 is actuated once more to dispense the weight difference, approximately two grammes in this case, into the receptacle by rotating the gear pump through the number of steps or rotations of the rotor member previously ascertained to produce the desired dispensed weight of two grammes. The secondary outlet means gear pump 5 is then stopped to close the secondary outlet means 3 and the final weight of dispensed ink in the receptacle is weighed for checking purposes. If the final weight is within the allowed tolerances the dispensed ink is passed to the next stage in the mixing procedure. If the final weight is outside the desired weight tolerances the operator of the apparatus will decide whether or not to use the weighed amount of ink and will check the apparatus for corrective action to be taken. If it is wished to dispense a desired weight of liquid ink below a certain weight, such as blow a weight of ten grammes, from the apparatus the presser plate 21 is actuated to urge the ink in the container 1 towards the main and secondary outlet means 2 and 3 but the secondary outlet means 3 only is actuated to dispense fluid material such as liquid ink therefrom into the receptacle on the weighing scales until a predetermined weight of fluid material such as ink of less than the desired weight, such as about eight grammes, has been dispensed, and is then shut-off. The dispensed liquid ink in the receptacle is weighed to give an actual weight value and the weight difference between the desired weight and the actual weight is calculated. The secondary outlet means gear pump 5 is then reactuated to dispense the weight difference, approximately two grammes, into the receptacle and then closed once more and the final weight of dispensed liquid ink in the receptacle is weighed for checking purposes as before. As previously indicated the number of steps or turns required to displace the rotor member in the gear pump 5 can be determined for any particular fluid material to be dispensed depending upon its particular flow, specific gravity and weight characteristics. The stepper motor 7 in general can operate the gear pump 5 and the rotor member thereof at about 400 steps per revolution making possible a very fine control of the amount of fluid material dispensed from the secondary outlet means 3. It is a simple matter to dispense into an empty receptacle as much ink from the container 1 as dispensed by say 400 turns of the motor 7 and gear pump rotor member, and calculate from this what weight is dispensed by one turn. For that particular ink in the container 1 it is a simple matter thereafter to calculate the number of steps the stepper motor 7 must be operated to produce the required fine control weight of ink to be dispensed from the secondary outlet means 3. Additionally a further way of improving the accuracy of the weigh of ink dispense from the secondary outlet means 3 lies in the use of the blast of compressed air through the inlet 14 through the gap between the tapered surface of the nozzle member 8 and inner edge 12a of the membrane 12 across the outer end of the discharge aperture 9 to remove waste liquid ink therefrom. Moreover when the stepper motor 7 is stopped to stop operation of the gear pump 5 it can immediately after stopping be reversed in direction to reverse the direction of movement of the gear pump 5 and thus act to suck any remaining liquid ink in the discharge aperture 9 back up the flow passage 8a to prevent such material blocking the aperture 9. In the foregoing the construction and operation of a single apparatus of the invention has been discussed in detail. It is of course to be understood that the present invention also contemplates the provision, for dispensing desired weights of a plurality of fluid materials such as liquid base colour printing inks for shade mixing purposes, of a plurality of dispensing apparatus as hereinbefore described, one for each particular fluid material to be dispensed. Such an apparatus also includes at least one weighing scale (not shown) and at least one receptacle (not shown) on the scale for receiving the or each fluid material being dispensed. The weighing scale with the carried receptacle and the plurality of dispensing apparatus are movable relative to one another to bring each selected dispensing apparatus in turn into registry with the receptacle and weighing scale for dispensing purposes. Control means may be provided including a micro-computer and a memory for storing the weight of each particular fluid material such as base colour inks in each dispensing apparatus corresponding to a desired number of actuating steps of each secondary outlet means gear pump 5 and for controlling the dispensing of fluid material from each dispensing apparatus in accordance with a one hundred part by weight formula inserted in the control means and the sequence of dispensing for each dispensing apparatus. To this end the control means may include a means for reading the hundred part formula, provided conveniently on a card, and converting the readings directly into control signals for actuating the desired dispensing apparatus containing the particular base colour inks to be dispensed to form the required shade, automatically. To this end the control means can also utilize the individual dispensing means secondary outlet means gear pump 5 data derived for the individual inks to control the operation of the individual secondary outlet means 3 for each individual ink to the desired degree of accuracy. Additionally the control means can also receive signals from the contact switches 29 on individual dispensing apparatus and make provision for refilling the respective containers 1 when the level of ink therein drops below the half way mark.

Claims: A method of dispensing a desired weight of fluid into a receptacle, including: (a) positioning a fluid material container (1) provided with a main fluid material discharge outlet means (2) and a secondary fluid material discharge outlet means (3) above the receptacle which is provided on a weighing scale for weighing the receptacle; (b) applying pressure to the material in the container to urge the material towards the main and secondary outlet means; (c) selectively actuating either the main and secondary outlet means together when a desired final weight of material to be dispensed is over a predetermined threshold value, or the secondary outlet means alone when the desired final weight of material to be dispensed is less than the threshold value; (d) then shutting-off the main outlet means, if actuated, when the weight of dispensed material is approximately a primary predetermined amount less than the desired final weight; (e) then shutting-off the secondary outlet means when the weight of dispensed material is approximately a secondary predetermined amount less than the desired final weight; (f) then determining the actual weight of the dispensed material in the receptacle; (g) then calculating the weight difference between the desired final weight and the determined actual weight; (h) then actuating the secondary outlet means to dispense a weight of material into the receptacle equal to the calculated weight difference; and (i) then checking the actual final weight of the dispensed material in the receptacle. A method according to claim 1, in which the secondary outlet means includes a gear pump (5) and a drive motor (7) and wherein the method further comprises actuating the gear pump in increments each of which causes a specific volume of material to be dispensed from the secondary outlet means in step "h" by rotation of the gear pump by a number of increments corresponding to the calculated weight difference of fluid material to be dispensed from the secondary outlet means, and in which the weight of the material dispensed in a single increment is ascertained by previously weighing the amount of the particular material dispensed in a known number of gear pump increments and calculating from the weighed amount the weight dispensed in a single gear pump increment. A method according to claim 2, including reversing the gear pump at the end of each secondary outlet means dispensing actuation to suck back residual material from a discharge aperture (9) of a nozzle member (8) of the secondary outlet means to keep the discharge aperture clear and introducing a gas under pressure across the outer side of the nozzle member discharge aperture to remove any remaining material hanging therefrom. A method as claimed in any preceding claim, wherein the material to be dispensed is a liquid base colour printing ink. An apparatus for dispensing a desired weight of a fluid material, comprising: a container (1) for the fluid material to be dispensed; a main fluid material discharge outlet means (2) on the container and actuable to dispense material from the container; a secondary fluid material discharge outlet means (3) on the container and actuable to dispense material from the container; means (4) for applying pressure to the material in the container to urge the material towards the main and secondary outlet means; a receptacle for receiving material dispensed by the main and secondary outlet means; a weighing scale on which the receptacle is provided for weighing the receptacle; and control means operable: (a) to actuate selectively either the main and the secondary outlet means together when a desired final weight of material to be dispensed is over a predetermined threshold value, or the secondary outlet means alone when the desired final weight of material to be dispensed is less than the threshold value; (b) then to shut-off the main outlet means, if actuated, when the weight of dispensed material is approximately a primary predetermined amount less than the desired final weight; (c) then to shut-off the secondary outlet means when the weight of dispensed material is approximately a secondary predetermined amount less than the final weight; (d) then to read the weighing scale to determine the actual weight of the dispensed material in the receptacle; (e) then to calculate the weight difference between the desired final weight and the determined actual weight; (f) then to actuate the secondary outlet means to dispense a weight of material into the receptacle equal to the calculated weight difference; and (g) then to read the weighing scale to check the actual final weight of material dispensed in the receptacle. Apparatus according to claim 5, wherein the secondary outlet means includes a gear pump (5) having a drivable rotatable toothed rotor member and a meshing idler gear contained in a housing chamber in fluid communication, at an inlet side (5a) of the rotor member and gear, with the container and at the outlet side (5b) of the rotor member and gear with an outlet nozzle assembly (6) of the secondary outlet means, and wherein the secondary outlet means also includes a drive motor (7) which is operable by the control means to rotate the rotor member in steps so that a required weight of material can be dispensed by rotation of the rotor member by a corresponding number of steps, the control means being provided with data representing the weight of the particular material dispensed per step of the rotor member. Apparatus according to claim 6, wherein the outlet nozzle assembly of the secondary outlet means includes a substantially cylindrical nozzle member (8) having a fluid flow passage therethrough opening into a discharge aperture (9) through one end of the nozzle member and having an external surface (10) at said discharge aperture end tapering towards the discharge aperture, a housing member (11) around at least said tapered end of the nozzle member, an annular sheet-like membrane (12) secured around its outer edge to said housing member so that its inner edge (12a) lies closely adjacent to the tapered end of the nozzle member adjacent and around the discharge aperture therethrough, which tapered external surface of the nozzle member, surrounding housing member and membrane define therebetween a substantially annular chamber (13), and an inlet (14) opening into said substantially annular chamber through which a gas under pressure can be fed from a source into the substantially annular chamber and thence through the gap between the nozzle member end and inner edge of the membrane, across the outer end of the discharge aperture through the nozzle member to blow away therefrom any fluid material remaining thereon, for cleaning purposes. Apparatus according to any one of claims 5 to 7, wherein the main outlet means includes an outlet passage (2a) and a ball valve (15) selectively actuable to open or close said passage to flow of fluid material therethrough from the container. Apparatus according to any one of claims 5 to 8, wherein the container is substantially cylindrical in shape having a closed base (16) at one end in and on which the main and secondary outlet means are provided, and an openable and closeable lid (17) at the other end. Apparatus according to claim 9, wherein the lid is hingeably connected to said container. Apparatus according to claim 9 or claim 10, wherein the means for applying pressure to fluid material when in the container is a presser plate (21) slidably movable in the container in sealed contact with the side walls (1a) thereof to engage the upper surface, via an intermediate sheet membrane, of fluid material in the container, and a piston and cylinder assembly (23) operative to urge the presser plate towards and away from the fluid material in the container, said piston and cylinder assembly having a cylinder (24) fixably secured to the container lid substantially perpendicular thereto and a piston rod (25) extensible from the cylinder and connected at its outermost end to the presser plate substantially perpendicularly thereto. Apparatus according to claim 11, wherein the presser plate is provided with a guide rod (28) projecting therefrom substantially parallel to the piston rod and projecting through an opening in the container lid, said guide rod visually indicating the position of the presser plate in the container and hence the volume of fluid material remaining in the container, a contact switch (29) being associated with the guide rod and operative to indicate the position of the guide rod corresponding to the half empty state of the container. Apparatus according to claim 11 or claim 12, wherein the presser plate incorporates an air bleed valve (30) operable to bleed air from the container from the fluid material side of the presser plate. An apparatus for mixing desired weights of fluid material, comprising a plurality of dispensing apparatus as claimed in any of claims 5 to 13 with the receptacle, weighing scale and control means being common to all of the dispensing apparatus, the containers being movable relative to one another selectively to bring the outlet means of the containers in turn into registry with the receptacle, and the control means being operable to cause material to be dispensed in turn from the containers in accordance with a stored 100 part by weight formula.

Inventors: SMITH, JOHN ARTHUR GEORGE
Applicants: JAMESON LIMITED
Application year: 1987
Main classification: G01G13
IPC codes: B01F15, B44D3, G01G13