Abstract
The invention provides a powder dispenser comprising a tube of circular cross-section; an auger extending axially through the tube; and a disc-shaped distributor extending laterally to the axis of the tube and partially closing the tube, wherein the disc-shaped distributor comprises a central ring and arms extending radially therefrom, characterised in that, the central ring has a radius of between 55%-90% of the internal radius of the tube; at least one of the arms extends to no more than 1 mm from the internal wall of the tube; and wherein there is a distance defined by a ciruculararcconcen tric with the tube between each arm at a distance of 1 mm from the tube wall of between 30%-65% of the internal radius of the tube.
Claims
1: A powder dispenser comprising a tube of circular cross-section; an auger extending axially through the tube; and a disc-shaped distributor extending laterally to the axis of the tube and partially closing the tube, wherein the disc-shaped distributor comprises a central ring and arms extending radially therefrom, characterised in that, the central ring has a radius of between 55%-90% of the internal radius of the tube; at least one of the arms extends to no more than 1 mm from the internal wall of the tube; and wherein there is a distance defined by a circular arc concentric with the tube between each arm at a distance of 1 mm from the tube wall of between 30%-65% of the internal radius of the tube.
2: The powder dispenser of claim 1 wherein the powder dispenser is a beverage powder dispenser.
3: The powder dispenser of claim 1 wherein the circular arc distance, concentric with the tube, between each arm of the disc-shaped distributor at a distance of 1 mm from the tube wall is between 35% and 65% of the internal radius of the tube.
4: The powder dispenser of claim 1 wherein the circular arc distance between each arm of the disc-shaped distributor at a distance of 1 mm from the tube wall is between 2 mm and 7.5 mm.
5: The powder dispenser of claim 1 wherein the radius of the central ring of the disc-shaped distributor is between 55% and 85% of the internal radius of the tube.
6: The powder dispenser of claim 1 wherein the internal radius of the tube is between 10 mm and 14 mm and the radius of the central ring of the disc-shaped distributor is between 7 mm and 9 mm.
7: The powder dispenser of claim 1 wherein the internal radius of the tube is between 7 mm and 9 mm and the radius of the central ring of the disc-shaped distributor is between 5 mm and 7 mm.
8: The powder dispenser of claim 1 wherein the disc-shaped distributor comprises between 4 and 12 arms.
9: The powder dispenser of claim 8 the disc-shaped distributor comprises between 6 and 10 arms.
10: The powder dispenser of claim 1 wherein the central ring of the disc-shaped distributor further comprises at least one aperture, each with a maximum width, in a direction along the radius of the tube, of no more than 30% of the radius of the tube.
11: The powder dispenser of claim 1 wherein the central ring of the disc-shaped distributor further comprises at least one aperture, each with a maximum width, in a direction along the radius of the tube, of no more than 2.5 mm.
12: The powder distributor of claim 10 wherein the central ring of the disc shaped ring comprises apertures and wherein, the area of all apertures in is no more than 15% of the cross-sectional area of the tube.
13: The powder dispenser of claim 1 wherein the disc-shaped distributor is within 10 mm, 20 mm, 30 mm, 40 mm, or 50 mm of the end of the tube.
14: The powder dispenser of claim 1 wherein the auger and disc-shaped distributor are operably connected.
15: The powder dispenser of claim 1, wherein the powder dispenser further comprises a powder with Hausner's ratio of between 1.00-1.25.
16: A method of dispensing powder comprising steps of: A—providing the powder dispenser of claim 1; B— adding a powder; C— rotating the auger and/or disc-shaped distributor; D—collecting the powder in a container.
17: The method of claim 16 wherein, the powder is a beverage powder.
Description
DETAILED DESCRIPTION OF THE INVENTION
[0067] In order that the invention may be more clearly understood embodiments thereof will now be described, by way of example only, with reference to the accompanying drawings, of which:
[0068] FIG. 1 is a schematic cross-section of a powder filling machine (1) of the prior art.
[0069] FIG. 2 is a top down view of a spinning disc (14) of the prior art used in conjunction with the powder filling machine (1) of FIG. 1.
[0070] FIGS. 3a-j are perspective views of numerous different failing designs of spinning discs (14) used in conjunction with the powder filling machine (1) of FIG. 1 and not falling within the scope of the spinning discs used in the claimed invention.
[0071] FIGS. 4a-c FIG. 4a is a perspective view of a first embodiment of a spinning disc used in conjunction with the powder filling machine (1) of FIG. 1, and which together form a powder dispenser of the invention. FIG. 4b is a plan view and FIG. 4c is a side-view of the same spinning disc.
[0072] FIGS. 5a-c FIG. 5a is a perspective view of a second embodiment of a spinning disc used in conjunction with the powder filling machine (1) of FIG. 1, and which together form a powder dispenser of the invention. FIG. 5b is a plan view and FIG. 5c is a side-view of the same spinning disc of the invention.
[0073] FIGS. 6a-c FIG. 6a is a perspective view of a third embodiment of a spinning disc used in conjunction with the powder filling machine (1) of FIG. 1, and which together form a powder dispenser of the invention. FIG. 6b is a plan view and FIG. 6c is a side-view of the same spinning disc of the invention.
[0074] FIG. 7 is a perspective view of an alternative embodiment of the spinning disc of FIG. 6 used in conjunction with the powder filling machine (1) of FIG. 1, and which together form a powder dispenser of the invention.
[0075] FIG. 8 is a perspective view of another alternative embodiment of the spinning disc of FIG. 6 used in conjunction with the powder filling machine (1) of FIG. 1, and which together form a powder dispenser of the invention.
[0076] FIG. 1, shows a powder filling machine (1) of the prior art comprising a hopper (10); a vertical auger (12) extending through and out of the hopper and into a tube (13) connected to the downstream end of the hopper; a means of rotating the auger, in the form of a motor (not shown); a powder dispersion means, in the form of a spinning disc (14); a packaging material, in the form of flow wrap (16); and a packaging sealing means (18). The auger (12) extends from a motor (not shown) into the hopper (10) and down into the tube (13). The spinning disc (14) is attached to the end of the auger (12) within the tube (13) partially closing the tube (13) close to its end. The spinning disc (14) has an overall diameter sufficiently less than the internal diameter of the tube (13) in order to allow it to rotate freely within the tube (13) whilst preventing powder flow between the outer edge of the disc and the tube wall. The flow wrap (16) rests along the outside surface of the tube (13) and the packaging sealing means (18) is beyond the end of the tube (13).
[0077] In use, the hopper (10) is loaded with powder to be dispensed from the tube (13). The spinning disc (14) and auger (12) are rotated together by the motor (not shown). The auger (12) drives the powder through the tube (13) and the spinning disc (14) disperses and dispenses the powder from the end of the tube (13) into the flow wrap (16). When not being rotated, the auger (12) no longer drives powder through the tube (13) and the spinning disc (14), no longer rotating, has shape and size configured to arrest the flow of powder from the tube (13) and prevent any “dribbling” of powder from the tube (13) in this stationary state. The duration of the period of rotation of the auger (12) and spinning disc (14) determine how much powder is dispensed into the flow wrap (16). Upon cessation of the rotation of the auger (12) and spinning disc (14), the sealing means (18) seals the flow wrap providing a top seal on the filled package and a bottom seal for the next package. Prevention of “dribbling” is important to produce a good seal between faces of the flow wrap (16) and correct packaging fill volume.
[0078] With reference to FIG. 2, where like numbers represent like components compared to FIG. 1, the spinning disc of the prior art (14) has an overall diameter of 24 mm and comprises a central ring (22) with radius 5.5 mm; 8 arms (24) and a central attachment means, in the form of a hole (26) with radius 4.05 mm. The 8 arms (24) extend from and are evenly spaced about the circumference of the ring (22); each arm (24) has a width of 2 mm. The largest diameter of the spinning disc (14) is 24 mm and it is designed to be used at the end of the tube (13) of the powder filling machine (1) of FIG. 1.
[0079] The spinning disc of FIG. 2 when used in conjunction with the powder filling machine (1) of 1, with an industry standard tube (13) having an external diameter of 45 mm and an internal diameter of 25 mm (radius 12.5 mm), is not of the invention, as the central ring (22) has a radius of 44% of the radius of the tube (13) and the circular arc distance, concentric with the tube, between each arm of the disc-shaped distributor at a distance of 1 mm from the tube wall is 7.42 mm, 59.4% of the internal radius of the tube (13).
[0080] It will be understood that when describing the spinning discs various dimensions are relied upon. With reference to the spinning disc (14) of FIG. 2, when describing the radius of the ring of a spinning disc (22) the radius is measured from the theoretical centre of the disc to the outer edge of the ring. When describing the radius of a disc (14), measurement is taken from the theoretical centre of the disc to the outer tip of the point on the disc that is furthest from the centre, in most embodiments of the invention, this point is the tip of one of the arms (24). A diameter is therefore calculated as a radius multiplied by 2.
[0081] With reference to FIGS. 3a-3h: FIG. 3a is of a spinning disc comprising a central attachment hole with radius 4.05 mm; a central ring with radius 5.5 mm and 12 arms; FIG. 3b is of a spinning disc comprising a central attachment hole with radius 4.05 mm; a central ring with radius 5.5 mm and 14 arms; FIG. 3c is of a spinning disc comprising a central attachment hole with radius 4.05 mm; a central ring with radius 5.5 mm and 5 1.5 mm wide radial slots; FIG. 3d is of a spinning disc comprising a central attachment hole with radius 4.05 mm; a central ring with radius 5.5 mm and 2.5 mm wide radial slots; FIG. 3e is of a spinning disc comprising a central attachment hole with radius 4.05 mm and 12 1.5 mm wide radial slots; FIG. 3f is of a spinning disc comprising a central attachment hole with radius 4.05 mm and 11 radial slots; FIG. 3g is of a spinning disc comprising a central attachment hole with radius 4.05 mm and 8 5 mm diameter holes; FIG. 3h is of and a spinning disc comprising a central attachment hole with radius 4.05 mm; an array of 2.5 mm diameter holes and an undulating perimeter. Each of the spinning discs of FIGS. 3a-3h have a largest diameter of 24 mm and are designed to be used at the end of the tube (13) of the powder filling machine (1) of FIG. 1.
[0082] None of the spinning discs of FIGS. 3a-3h when used in conjunction with the powder filling machine (1) of FIG. 1, with tube (13) internal diameter of 25 mm, are of the invention. With reference to FIG. 3a, the central ring has a radius of 44% of the radius of the tube (13) and the circular arc distance, concentric with the tube, between each arm of the disc-shaped distributor at a distance of 1 mm from the tube wall is 4.28 mm, 34.3% of the radius of the tube (13). With reference to FIG. 3b, the central ring has a radius of 44% of the radius of the tube (13) and the circular arc distance, concentric with the tube, between each arm of the disc-shaped distributor at a distance of 1 mm from the tube wall is 3.39 mm, 27.1% of the radius of the tube (13). With reference to FIGS. 3c; 3d; 3e; 3f and 3g, the central ring has a radius of 44% of the internal radius of the tube (13) and there are no arms or arm gaps. With reference to FIG. 3h there is no central ring, nor arms or arm gap.
[0083] FIGS. 4a-4c show a first embodiment of a spinning disc used in conjunction with the powder filling machine (1) of FIG. 1 to form a powder dispenser of the invention, with tube (13) internal diameter 25 mm (radius 12.5 mm), the spinning disc has height 2 mm (i.e. height in the longitudinal direction of the tube (13); a central attachment hole with radius 4.05 mm; a central ring with radius of 8 mm, 64% of the radius of the tube (13); ten arms extending from the central ring to a distance of 12 mm from the centre of the disc, with circular arc distance of 5.5 mm, 44.3% of the internal radius of the tube (13) at 1 mm from the tube wall.
[0084] FIGS. 5a-5c show a second embodiment of a spinning disc used in conjunction with the powder filling machine (1) of FIG. 1 to form a powder dispenser of the invention, with tube (13) internal diameter of 25 mm, is similar to that of FIGS. 4a-4c and differs only in that the central ring extends in height (longitudinal direction of the tube) 1 mm from the plane of the arms (i.e. is thicker in the longitudinal direction of the tube (13). Without wishing to be bound by theory, the inventors believe that if the central ring extends significantly more than 1 mm, such as for example 4 mm or more, from the plane of the arms a narrow channel and flow restriction is created between the side of the central ring and the tube wall increasing the likelihood and/or incidence of powder blockage of the tube over time.
[0085] The spinning disc of FIG. 5a-5c may be used in the powder filling machine (1) in either of the two possible orientations (central ring extending towards the hopper (10) or away from it). An embodiment of the invention, not shown, exists where the central ring extends by 1 mm from both sides of the disc. This embodiment has the particular advantage of being able to be used either way up to reduce the risk of installation error.
[0086] FIGS. 6a-6c show a third embodiment of a spinning disc used in conjunction with the powder filling machine (1) of FIG. 1 to form a powder dispenser of the invention, with tube (13) internal diameter of 25 mm, the spinning disc has height 2 mm; a central attachment hole with radius 4.05 mm; a central ring with radius 8 mm, 64% of the radius of the tube (13); the central ring comprises five 2.5 mm wide (20% of the internal radius of the tube) radial slots and ten 2 mm wide arms, extending from the central ring to a distance of 12 mm from the centre of the disc, with circular arc distance of 5.5 mm, 44.3% of the internal radius of the tube (13) at 1 mm from the tube wall. The five radial slots occupy a total area of 44.2 mm.sup.2, 9% of the cross-sectional area of the tube (13).
[0087] FIG. 7 shows a fourth embodiment of a spinning disc used in conjunction with the powder filling machine (1) of FIG. 1 to form a powder dispenser of the invention, with tube (13) internal diameter of 25 mm, the spinning disc is similar to that of FIGS. 6a-6c and differs only in that it comprises 12 arms with circular arc distance, concentric with the tube, between each arm of the disc-shaped distributor at a distance of 1 mm from the tube wall of 4.3 mm, 34.3% of the internal radius of the tube.
[0088] FIG. 8 shows a fifth embodiment of a spinning disc used in conjunction with the powder filling machine (1) of FIG. 1 to form a powder dispenser of the invention, with tube (13) internal diameter of 25 mm, the spinning disc of the invention is similar to that of FIG. 6a-6c and differs only in that the central ring comprises five 1.5 mm wide (12% of the internal radius of the tube) radial slots. The five radial slots occupy a total area of 20.67 mm.sup.2, 4.2% of the cross-sectional area of the tube (13).
Example 1—First Test Powder
[0089] A model TM70-ZC, manufactured by Toyo Machine Manufacturing Co. Ltd Powder filling machine (1) with the layout of FIG. 1, with a tube (13) with outside diameter of 45 mm and an internal diameter of 25 mm was provided and the hopper (10) filled with a First test powder.
[0090] The First test powder was a spray dried powder comprising: 37% sugar, 19% skimmed milk powder, 37% creamer, 0.5% xanthan gum, 1% flavour and 5.5% soluble coffee, having Hausner's ratio 1.08, a ‘very free-flowing powder’ by the classification of Table 1, and x50 particle size distribution 197 microns.
[0091] A composite flow wrap packaging material was fitted around the tube (13) of the powder filling machine of FIG. 1 in order to produce a stick pack package of 45 mm diameter and 180 mm length.
[0092] The Powder filling machine was set to run at a rate of 37 stick packs per minute with a powder fill weight of 21.5 g.
[0093] The auger was set to rotate at a rate of 35-42 rotation per minute.
[0094] Each of the different designs of spinning discs (14) of FIGS. 2-3 (not falling within the scope of the claimed invention) and FIGS. 5-8 (falling within the claimed scope of the invention) were attached to the end of the auger (12) by the central attachment hole (26); the powder filling machine was run for 6 hours for each different disc, whilst 1. The extent of blockage of the tube (13) by the First test powder, during operation, and 2. The extent of test powder leakage through the spinning disc (14), when rotation was stopped, were both measured. The results are recorded in Table 2.
TABLE-US-00002 TABLE 2 Results of trials with numerous different spinning disc designs and a First test powder. 2. Extent of powder leakage past disc Spinning disc ID 1. Extent of tube blockage when not rotating FIG. 2 Not blocked after 6 hours Powder flow not arrested FIG. 2: variant Not blocked after 6 hours Powder flow not arrested with 10 arms FIG. 3a Blocked before completion No powder leakage of trial FIG. 3b Blocked before completion No powder leakage of trial FIG. 3c Blocked rapidly No powder leakage FIG. 3d Blocked rapidly No powder leakage FIG. 3e Blocked rapidly No powder leakage FIG. 3f Blocked rapidly No powder leakage FIG. 3g Blocked rapidly Powder flow not arrested FIG. 3h Blocked before completion Powder flow not arrested of trial FIGS. 4a-c (of the Not blocked after 6 hours No powder leakage invention) FIGS. 5a-c (of the Not blocked after 6 hours No powder leakage invention) FIGS. 6a-c (of the Not blocked after 6 hours No powder leakage invention) FIG. 7 (of the Not blocked after 6 hours, No powder leakage invention) some signs of powder build up on the disc FIG. 8 (of the Not blocked after 6 hours, No powder leakage invention) some signs of powder build up on the disc
[0095] The spinning disc of FIG. 2 and a variant of the spinning disc of FIG. 2 with 10 arms evenly spaced around the circumference of the disc did not prevent powder flow from the tube (13) when rotation was stopped. Without wishing to be bound by theory, the inventors believe that these discs lacked sufficient body towards the centre of the tube to provide a surface for the powder to stack upon when not in rotation, such that even when a variant with 10 arms was substituted, powder flow was not prevented. The spinning disc of the FIG. 2 variant with 10 arms had identical dimensions to that of FIG. 2, varying only in that it comprised 10 arms and the gap between the arms at, a distance of 1 mm from the tube wall, was 5.5 mm (44.3% of the radius of the tube)
[0096] The spinning discs of FIGS. 3a, 3b stopped powder flow when not in rotation yet resulted in build-up of powder back through the tube during the period of the trial. These spinning discs are simple 12 and 14 arm variants of the spinning disc of FIG. 2. Without wishing to be bound by theory, the inventors believe that the introduction of additional arms had the effect of preventing the flow of powder when not in rotation yet introduced sufficient additional body to the spinning discs such that powder did not flow freely from the tube when in rotation throughout the duration of the trial.
[0097] The spinning discs of FIGS. 3c, 3d, 3e, 3f and 3g all stopped powder flow when not in rotation yet resulted in build-up of powder back through the tube during the period of the trial. Without wishing to be bound by theory, the inventors believe that the distribution of mass about the body of these discs did not take sufficient advantage of the forces imposed by rotation to allow the free-flowing of the test powder when under rotation and highlight the difficulty felt in overcoming the challenges of the prior art.
[0098] The spinning disc of FIG. 3h neither prevented flow when not in rotation nor prevented build-up of powder and blockage of the tube during the trial.
[0099] The spinning discs of FIGS. 4a-c, 5a-c, 6a-c, 7 and 8 all showed good performance in stopping powder flow when not in rotation and did not result in a blocked tube during the period of the trial. Without wishing to be bound by theory, the inventors believe that the additional body provided by a central ring with the dimensions as claimed in combination with the gap between the arms at 1 mm from the internal wall of the tube (13) in these embodiments provide a surface sufficient for powder build up within the tube when the disc is not in rotation yet when in rotation allow sufficient void space between the arms for powder to flow freely past the disc. The spinning discs of FIGS. 7 and 8 showed some signs of powder build up on the arms of the spinning disc after the trial period, without wishing to be bound by theory, the inventors believe this slight build up to attributed to the number of arms and gap between the arms being close to the limit of the scope of the invention.
Example 2—Second Test Powder
[0100] A second set of trials were conducted in an identical way to those of Example 1, the only change made was that a Second test powder was used rather than the First test powder of Example 1. The Second test powder was a spray dried powder with the same composition as the First test powder but because of different spray drying process parameters and extent of drying had a higher Hausner's ratio of 1.18 and was a ‘free-flowing powder’ by the classifications in Table 1.
[0101] The results of the second set of trials with the Second test powder are given in Table 3.
TABLE-US-00003 TABLE 3 Results of trials with numerous different spinning disc designs and a Second test powder. 2. Extent of powder leakage past disc Spinning disc ID 1. Extent of tube blockage when not rotating FIG. 2 Not blocked after 6 hours Powder flow not arrested FIG. 2: variant Not blocked after 6 hours Powder flow not arrested with 10 arms FIG. 3a Blocked rapidly No powder leakage FIG. 3b Blocked rapidly No powder leakage FIG. 3e Blocked rapidly No powder leakage FIG. 3d Blocked rapidly No powder leakage FIG. 3e Blocked rapidly No powder leakage FIG. 3f Blocked rapidly No powder leakage FIG. 3g Blocked rapidly Powder flow not arrested FIG. 3h Blocked rapidly Powder flow not arrested FIGS. 4a-c Showing signs of build-up No powder leakage but not blocked after 6 hours FIGS. 5a-c Showing signs of build-up No powder leakage but not blocked after 6 hours FIGS. 6a-c Not blocked after 6 hours No powder leakage FIG. 7 Not blocked after 6 hours, No powder leakage some signs of powder build up on the disc FIG. 8 Not blocked after 6 hours, No powder leakage some signs of powder build up on the disc
[0102] Results were generally comparable to those of Example 1, with a general trend towards more tube blockages and less powder leakage with the less free-flowing powder of Example 2. The disc designs of FIG. 2 and the variant of FIG. 2 with 10 arms failed in the same way as Example 1. The disc designs of FIGS. 3a-3h failed by blocking of the tube more rapidly and the design of FIG. 3d did not fail by leakage of powder when not in rotation. As in Example 1, the spinning disc designs of FIGS. 4a-c, 5a-c, 6a-c, 7 and 8 stopped powder flow and did not block over the period of the trial with this less free-flowing Second test powder.
[0103] The spinning discs of FIGS. 6a-c, 7 and 8 showed enhanced resistance to build up of powder in the tube during operation. Without wishing to be bound by theory, the inventors believe that this was due to the passage of air through the piercings within the central ring of the spinning disc reducing any pressure build up beyond the spinning disc. Said piercings are believed to be sufficiently small so as not to compromise the powder stopping properties given by the enlarged central ring.
[0104] Without wishing to be bound by theory, the inventors believe that the distance between arms, the dimensions of the central ring, dimensions of any optional solid outer perimeter and the size and placement of any additional, optional, apertures through the disc are key to a successful spinning disc of this invention.
Example 3—35 mm Outside Diameter, 16 mm Inside Diameter Tube
[0105] Scaled-down variants of the spinning discs of FIGS. 2-7 used in Examples 1 and 2 were used in a powder filling machine of FIG. 1 with tube (13) scaled-down to an outside diameter of 35 mm and an inside diameter of 16 mm.
[0106] The scaled-down variants of the spinning discs had the following dimensions:
[0107] Each scaled-down disc had a central attachment hole with radius 2.5 mm, arm width of 1.5 mm (measured across the cross-section of the tube) and a disc diameter of 15 mm
[0108] Other dimensions of the scaled-down spinning disc are as shown in Tables 4, 5 and 6.
TABLE-US-00004 TABLE 4 Dimensions of scaled-down spinning discs of FIGS. 2-3c. Alt. FIG. 2 FIG. 2 (10 arm) FIG. 3a FIG. 3b FIG. 3c for for for for for 35 mm 35 mm 35 mm 35 mm 35 mm tube tube tube tube tube central ring radius 4 4 4 4 4 (mm) central ring radius 50.0% 50.0% 50.0% 50.0% 50.0% (% of tube radius) number of arms 8 10 12 14 N/A circular arc distance 4.39 3.21 2.43 1.87 N/A between arms 1 mm from tube (mm) circular arc distance 54.9% 40.2% 30.3% 23.3% N/A between arms 1 mm from tube (% of tube radius)
TABLE-US-00005 TABLE 5 Dimensions of scaled-down spinning discs of FIGS. 3d-5. FIG. 3d FIG. 3e FIG. 3f FIG. 3g FIG. 3h FIGS. 4a-c FIGS. 5a-c for for for for for for for 35 mm 35 mm 35 mm 35 mm 35 mm 35 mm 35 mm tube tube tube tube tube tube tube central ring radius 4 4 4 4 4 5.5 5.5 (mm) central ring radius 50.0% 50.0% 50.0% 50.0% 50.0% 68.8% 68.8% (% of tube radius) number of arms N/A N/A N/A N/A N/A 10 10 circular arc distance N/A N/A N/A N/A N/A 3.21 3.21 between arms 1 mm from tube (mm) circular arc distance N/A N/A N/A N/A N/A 40.2% 40.2% between arms 1 mm from tube (% of tube radius)
TABLE-US-00006 TABLE 6 Dimensions of scaled-down spinning discs of FIGS. 6 and 7. FIGS. 6a-c FIG. 7 for for 35 mm 35 mm central ring radius 5.5 5.5 (mm) central ring radius 68.8% 68.8% (% of tube radius) number of arms 10 12 circular arc distance 3.21 2.43 between arms 1 mm from tube (mm) circular arc distance 40.2% 30.3% between arms 1 mm from tube (% of tube radius) Number of slots 5 5 Slot width (mm) 1.5 1.5 [via radius of tube] Slot area (mm.sup.2) 16.6 16.6 Slot area (% of cross- 8.3% 8.3% sectional area of tube bore)
[0109] The 35 mm variants of FIGS. 2 and 3a-j when used in conjunction with the scaled-down powder filling machine (1) of FIG. 1, with tube (13) outside diameter of 35 mm, are not of the invention.
[0110] The 35 mm variants of FIGS. 4-7 when used in conjunction with the scaled-down powder filling machine (1) of FIG. 1, with tube outside diameter of 35 mm, are of the invention.
[0111] The scaled-down powder filling machine (1) of FIG. 1, was fitted with each of the scaled-down spinning discs in Tables 4, 5 and 6 and loaded with the test powders of Examples 1 and 2 in turn such that each combination of spinning disc and test powder was tested. The same parameters of rotation speed, filling rate, test duration, etc of Example 1 were used.
[0112] A scaled-down equivalent of the spinning disc of FIG. 8 was not tested.
[0113] Results were found to be substantially the same as those obtained with the 45 mm versions used in Examples 1 and 2 with powder filling machines fitted with spinning discs of FIGS. 4-7 performing well in the tests of arresting powder flow when stationary yet preventing blockage of the tube (13) over time, were those fitted with spinning discs of FIGS. 2 and 3a-j failing one or both tests as in Examples 1 and 2.
[0114] Further variants of the scaled-down spinning discs of FIGS. 4-7 were tested with extended central rings up to radii of up to 6.8 mm, 85% of the internal radius of the tube in example 3 (all other dimensions remained the same). These variants showed the same excellent powder flow and stopping properties as those shown in Tables 4-6 without causing blockage over time.
[0115] The above embodiments are described by way of example only. Many variations are possible without departing from the scope of the invention as defined in the appended claims.
