US 2781947 A
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Description (OCR text may contain errors)
Feb. 19, 1957 J. G. WEBSTER ET AL 2,781,947
TABLET COUNTING AND BATCHING MACHINES Filed April 7, 1952 2 Sheets$heet l FIG. 4.
|NVENTORS= JAMES e. WEBSTER, DECEASED BY GABRIEL P. CLAY, AND HUGH c. PEARSON, EXECUTOR$ LEsmE ALDRED- Feb. 19, 1957 J. G. WEBSTER ET AL 2,781,947
TABLET COUNTING AND BATCHING MACHINES Filed April 7, 1952 2 Sheets-Sheet 2 FIG.5 F166.
, I INVENTORS= JAMES e. WEBSTER, DECEASED BY GABRIEL P. CLAY, AND
HUGH C. R. PEARSON, EXECUTORS.
BM JW Arron/mm.
United States Patent TABLET COUNTING AND BATCHEJG MACHINES James Gordon Webster, deceased, late of Blackley, Manchester, England, by Gabriel P. Clay, Witton, Birmingham, and Hugh Christopher Russel Pearson, Manchester, executors, and Leslie Aldred, lilackley, Manchester, England, assignors to Imperial Chemical Industries Limited, a corporation of Great Britain Application April 7, 1952, Serial No. 281,014
Claims priority, application Great Britain April 11, 1951 4 Claims. (Cl. 221-296) This invention relates to tablet counting and batching machines and more particularly to means for delivering a predetermined number of tablets.
Various methods have been proposed and employed for counting and delivering predetermined numbers of tablets for packing into containers. Thus for example, the average weight of the predetermined number of tablets may be ascertained and used as a measure of the number of tablets. This method, however, is liable to serious errors when the number of tablets in each batch is large, for example over 100.
In another method there are used hand operated shovels, ortheir mechanised equivalents, having a flat surface in which there are a number of depressions each of a suitable size to contain one tablet. This method is not suitable for batching large numbers of tablets; the accuracy of the method depends entirely on visual inspection and the work of inspection and inserting missing tablets is tedious and unsuited to rapid handling.-
Another method has been used wherein the tablets are guided in single file into one or more sloping or vertical chutes and then by mechanical means, all of the tablets except for a predetermined number are retained in the chute, while a gate at the bottom of the chute is opened to release the predetermined number of tablets. In this method, however, the mechanical means for retaining the tablets must be carefully designed and adjusted, to avoid crushing some tablets by pressure or by insuflicient pressure failing to retain some.
The present invention is directed to an improvement in this use of a chute in counting and batching tablets wherein novel means are provided for holding a predetermined tablet against one of the walls of the chute so that it arrests the flow.
More particularly this invention comprises the application to one or more of the tablets to be retained of air pressure or suction, i. e. differential air pressure.
The application of the air pressure or suction to the tablet may be achieved by the introduction, at an appropriate place in the chute, of a small orifice connected through a suitable valve to a source of air pressure or suction.
The magnitude of the air pressure or suction is not critical provided it is greater than the minimum required to retain the tablets, since there is no possibility of damaging the tablets under any practicable operating conditions. The retaining power of the air pressure or suction may be increased by increasing the pressure or suction or by applying it to several tablets simultaneously.
The gate at the bottom of the chute which, when opened, releases all of the tablets in the chute except for those retained by the application of the air pressure or suction, may be operated independently of the control of the air pressure or suction, or it may be operated in conjunction with that control. Thus, the operation of the valve controlling the air pressure or suction may be arranged to effect mechanically the opening or closing of is applied to the tablets. In order to achieve this preferred feature, the air pressure or suction is applied not. only to the tablets but. also to means such as bellows,
diaphragm or capsule for operating the gate. In this manner one movement of the control valve, applying; the air pressure or suction, retains the bulk of the tabletsin the chute and simultaneously opens the gate to release the predetermined number of tablets. On closing the valve, the gate is closed by a return spring or similar means, and the bulk of the tablets are allowed to move down the chute.
It has been stated above that the opening of the gate is simultaneous with the retention of the bulk of the tablets. However, owing to the volume of the. bellows or similar device, and also to the dimensions and inertia of the'gate, the opening of the gate is delayed somewhat, so that the retention of the tablets occurs before the gate is fully opened. Accordingly there is no possibility of the tablets escaping before the retention of the bulk of the tablets is efiected. Moreover, the closing of the gate by the return spring or gravity and the release of the bulk of the tablets being simultaneous, there is no possibility of tablets escaping after the air pressure or suction is removed, since the tablets must first move down to refill the chute.
The chute may be arranged so that the tablets move down, under the influence of gravity, in single file in any manner. Thus the tablets may fall, slide or roll or the chute may be tilted so that the tablets partly roll and partly slide, being in contact with one side of the chute; in the latter case asuction orifice wouldbe situated'in the side of the chute with which the tablets are in contact whereas an air pressure orifice would be situated in the opposite side.
The chute may be provided with a removable transparent cover to protect and retain the tablets, and means, such as suction, may be employed to remove any dust formed from the tablets.
When large batches of tablets are to be prepared, several chutes may advantageously be used in combination, being arranged to deliver tablets into one container. The air pressure. or suction for each chute may be derived from a common source and a single valve; the gates on the chutes may also be coupled together mechanically, or a single gate may be used, its width being sufiicient to cover all the chutes.
The valve controlling the air pressure or suction may be operated manually or automatically, for example by means of a mechanical device when a container is placed in position under the chute outlet or by means of a timing device or a photoelectric device. The valve may be a simple on and oil valve or it may be arranged to vent the bellows and orifice system to atmosphere when the air pressure or suction is turned off. In this manner a faster rate of working can be achieved.
The invention may be illustrated with reference to the accompanying drawings in which:
Figure l is a side elevation of a chute down which the tablets roll and which is controlled by air pressure.
Figure 2 is a plan of the same.
Figure 3 corresponds to Figure 1 after the opening of the valve and shows the release of the batch of tablets.
Figure 4 is a side elevation of a chute similar to that of Figure 1 but arranged for control by suction.
Figure 5 is a plan of a chute similar to that of Figure 3 1 but with the orifice in a dilferent position and adapted for control by either air pressure or suction.
Figure 6 is a plan of a chute down which the tablets slide and adapted for control by air pressure with use of two orifices. A similar chute using only one orifice could be used for suction control.
Figure 7 is a side elevation of a chute similar to that of Figure 6 but having a plurality of orifices, in different positions, and adapted for control by air. pressure or suction.
Figure 8 is a plan of a combination of a plurality of chutes similar to that of Figure 1.
In the drawings, tablets 2 are allowed to fall, roll or slide down a chute 1. An orifice opening to the chute is connected via a conduit 3, having a valve 9 therein, to an air pressure or suction source. This valve may be arranged to vent the orifice to atmosphere when the air pressure or suction connection is closed. A generally U-shaped gate 4 pivots about a fulcrum 5 between stops 6 and 7 and is operated by a bellows or the like 8, connected also to conduit 3 between the orifice and the valve 9. A suitable compression or tension spring 10 may be used, in lieu of gravity, to maintain the gate 4 in its closed position against stop 6.
By means of the simple device of this invention it is possible to count and batch large or small numbers of tablets at high speed and with absolute accuracy. Thus by using several chutes in combination very large batches may be prepared, of the order of 1000 or even more tablets; since the accuracy of counting depends upon the diameter of the tablet, which is normally very uniform, errors are almost impossible. Risk of damage to tablets is virtually eliminated since no mechanical obstacles are imposed upon the tablets. Moreover visual control of the batching process is very easily carried out, since the operator has only to ensure that the chute is filled above the lowest orifice and that, at the moment of release of tablets, the remainder of the tablets are retained; since these two checks are made at the same point, the visual effort required is small.
What we claim is:
1. In apparatus for counting or batching fragile tablets having a chute down which the tablets pass in single file and a gate at the lower end of the chute, the combination of means for applying difierential air pressure directly to at least one tablet at a location above the lower end of the chute, said pressure being of suflicient magnitude to retain said tablet and the tablets thereabove against downward passage when the gate is open, and means coordinating the operation of the gate with the application of the diiferential pressure.
2. In apparatus for counting or batching fragile tablets having a chute down which the tablets pass in single file and a gate at the lower end of the chute, the combination of means for applying differential air pressure directly to at least one tablet at a location above the lower end of the chute, said pressure being of sutficient magnitude to retain said tablet and the tablets thereabove against downward passage when the gate is open, diiferentiahpressure responsive means for operating the gate, and means for supplying said responsive means with the same pressure differential applied to the tablet.
3. The structure defined in claim 1 wherein the differential pressure means applies positive pressure to one side of the tablet.
4. The structure defined in claim 1 wherein the differential pressure means applies suction to one side of the tablet.
References Cited in the file of this patent UNITED STATES PATENTS 1,926,060 Peters Sept. 12, 1933 2,355,311 Linkner -s Aug. 8, 1944 2,367,393 Green Jan. 16, 1945 2,402,097 Spraker June 11, 1946 2,415,376 Strickland Feb. 4, 1947 2,457,083 Jordan Dec. 21, 1948 2,517,388 Daves Aug. 1, 1950 2,604,574 Riddell July 22, 1952 FOREIGN PATENTS 686,750 Germany Jan. 15, 1940 503,673 Belgium June 30, 1951 (Corresponding Great Britain 689,530, Apr. 1, 1953.)