Tablet press controller and method
First Claim
1. A controller for a tablet press having at least one die/punch combination, at least one compression station for applying a compression force to a quantity of powder fill in the die, a zone where a maximum compression force is applied to the powder fill, and means for generating a compression signal having a magnitude indicative of the magnitude of the compression force, the controller comprising:
- (a) monitor means for receiving and monitoring the compression signal and continuously providing, during at least the time the compression force is being applied, a data word having a value indicative of the magnitude of the compression signal;
(b) latch means for holding the highest value data word provided by the monitor means, the data word held by the latch means defining a latched data word;
(c) data processing means for reading the latched data word, processing the latched data word in a pre-established manner, including detecting if the value of the latched data word has exceeded or failed to exceed pre-established limits, and providing tablet press control signals for controlling the operation of the tablet press; and
(d) proximity signal input means for receiving and monitoring a proximity signal provided by the tablet press when the die/punch combination exits the maximum compression zone, and further for providing an indication of the occurence of the proximity signal to the data processing means, the data processing means being responsive to the occurence of the proximity signal to read the latched data word.
7 Assignments
0 Petitions
Accused Products
Abstract
A tablet press controller comprises means for receiving and monitoring a compression signal and providing a data word having a value indicative of the magnitude of the compression signal, data processing means for reading the data word and processing the data word in a pre-established manner, including detecting if the value of the data word exceeds or fails to exceed pre-established limits, and providing tablet press control signals for controlling the operation of the tablet press, including control signals for adjusting the level of powder fill in die cavities, control signals for activating divert gates for rejecting tablets, and signals generated in response to the occurence of one or more undesired vents for shutting down the tablet press.
81 Citations
46 Claims
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1. A controller for a tablet press having at least one die/punch combination, at least one compression station for applying a compression force to a quantity of powder fill in the die, a zone where a maximum compression force is applied to the powder fill, and means for generating a compression signal having a magnitude indicative of the magnitude of the compression force, the controller comprising:
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(a) monitor means for receiving and monitoring the compression signal and continuously providing, during at least the time the compression force is being applied, a data word having a value indicative of the magnitude of the compression signal; (b) latch means for holding the highest value data word provided by the monitor means, the data word held by the latch means defining a latched data word; (c) data processing means for reading the latched data word, processing the latched data word in a pre-established manner, including detecting if the value of the latched data word has exceeded or failed to exceed pre-established limits, and providing tablet press control signals for controlling the operation of the tablet press; and (d) proximity signal input means for receiving and monitoring a proximity signal provided by the tablet press when the die/punch combination exits the maximum compression zone, and further for providing an indication of the occurence of the proximity signal to the data processing means, the data processing means being responsive to the occurence of the proximity signal to read the latched data word. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. A rotary tablet press having a plurality of die/punch combinations rotatable through at least one compression station for applying a compression force to a quantity of powder fill in each of the dies, the compression station having a zone where a maximum compression force is applied, the tablet press comprising:
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(a) means for generating a first signal having a magnitude continuously indicative of the magnitude of the compression force, the first signal having a peak magnitude indicative of the magnitude of the maximum compression force; (b) means for generating a second signal for indicating that a die/punch combination has begun to exit the compression station and is no longer in the maximum compression zone; (c) means for monitoring the first signal and generating and holding a data word for each die/punch combination rotating through the compression zone, each data word having a value indicative of a peak magnitude of the first signal; (d) data processing means responsive to the second signal for reading and storing each data word, the data processing means processing the data word in a pre-established manner, including detecting if the value of the data word has exceeded or failed to exceed pre-established limits, and providing press control signals to control the operation of the press. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37)
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38. A method of controlling the operation of a tablet press of the type having a plurality of die/punch combinations moveable through a compression station for applying a compression force to a quantity of powder fill in each die, the compression station having a zone where a maximum compression force is applied, the method comprising:
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(a) providing a compression signal having a substantially sinusoidal waveform, the magnitude of the compression signal at any time being an indication of the magnitude of the compression force at that time, the compression signal having a peak magnitude indicative of the magnitude of the maximum compression force; (b) providing a proximity signal for indicating that one of the die/punch combinations is exiting the compression station and is no longer in the maximum compression zone, the proximity signal being an indication that the maximum compression force has been applied; (c) monitoring the compression signal and continuously providing, during at least the positive going portion of the sinusoid, a data word having a value indicative of the magnitude of the compression signal, the value of the data word increasing by an incremental amount when the magnitude of the compression signal has increased by a corresponding incremental amount; (d) holding in a memory circuit the highest value the data word achieves; (e) reading the data word held in the memory circuit when the proximity signal occurs; (f) processing the data word and providing press control signals for controlling the operation of the press. - View Dependent Claims (39, 40, 41, 42, 43)
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44. A controller for a rotary tablet press having a plurality of die/punch combinations rotatable through at least one compression station for applying a compression force to a quantity of powder fill placed in each die, the compression station having a zone where a maximum compression force is applied, the tablet press providing a substantially sinusoidal compression signal having a magnitude continuously indicative of the magnitude of the compression force, the compression signal having a peak magnitude indicative of the magnitude of the maximum compression force, the controller comprising:
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(a) classification means for classifying the compression signal into one or more of N successive categories, where N is an integer greater than 2, each successive category being assigned a successively increasing value, the classification means classifying the compression signal during at least the positive going portion of the sinusoid, the number of categories into which the compression signal is classified at any time being an indication of the magnitude of the compression signal at that time, the highest category into which the compression signal is classified being an indication of the peak magnitude of the compression signal, the classification means providing a N bit data word indicative of the highest category into which the compression signal has been classified; (b) first proximity probe input means for receiving a signal from a first proximity probe located a distance from the maximum compression zone of the compression station, the occurrence of the first proximity signal being an indication that one of the die/punch combinations has begun to exit the compression station and is no longer in the maximum compression zone and therefore being an indication that the maximum compression force has occurred; (c) second proximity probe input means for receiving a signal from a second proximity probe, the signal from the second proximity probe occurring when the press has completed a full rotation; (d) data processing means responsive to the first proximity probe signal for reading the data word provided by the classification mean each time the first proximity signal occurs, the data processing means being further responsive to the first proximity signal to compare the value of the data word to pre-established upper and lower alarm limits and provide a divert signal when the value of the data word has exceeded the upper alarm limit or has failed to exceed the lower alarm limit, the divert signal actuating a divert gate associated with the press for separating bad tablets from a stream of good tablets, the data processing means being responsive to the second proximity signal for; (i) computing the average value of all data words provided by the classification means during the preceding full rotation of the press; (ii) comparing the average value to pre-established upper and lower alert limits, the upper alert limit being less than the upper alarm limit and the lower alert limit being greater than the lower alarm limit; and (iii) providing powder fill adjust signals when the average value has exceeded the upper alert limit and when the average value has failed to exceed the lower alert limit, the powder fill adjust signals actuating a fill adjust mechanism associated with the press for altering the quantity of powder fill in the dies, the powder fill adjust signals being provided during each rotation of the press until the average value falls mid-way betwen the alarm limits. (e) means associated with the data processing means for keeping track of the number of tablets which have been manufactured and providing first user selectable control signal for affecting the operation of the press in a predefined manner when the number of tablets manufactured reaches a predetermined number; (f) means associated with the data processing means for maintaining a count of the number of times that the value of the data words exceed the upper alarm limit and fail to exceed the lower alarm limit and providing a second user selectable control signal for affecting the operation of the press in a predefined manner when the count reaches a predetermined count; (g) means responsive to the occurrence of one or more external events, such as a rise in operating temperature of the press for providing the second user selectable control signal for affecting the operation of the press in a predefined manner. - View Dependent Claims (45)
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46. In a tablet press having compression force means for applying a compression force to a quantity of powder fill, the compression force having a magnitude which varies with changes in the quantity of powder fill, the tablet press including a controller associated therewith, the controller having adjustable upper and lower thresholds defining an acceptable range of compression forces, the controller calculating and displaying an average value indicative of the average compression force, the average value being relative to the upper and lower thresholds, a method of setting the upper and lower thresholds comprising:
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(a) providing a desired weight of tablets to be manufactured by the tablet press; (b) operating the tablet press so that tablets are manufactured; (c) weighing a number of the tablets and computing the average weight thereof; (d) adjusting the quantity of powder fill if the average weight computed in step (c) is substantially different from the desired weight provided in step (a); (e) repeating steps (c) and (d) until the average weight computed in step (c) is substantially the same as the desired weight provided in step (a) and then recording the average weight as a first average weight; (f) recording the average value displayed by the controller as a first average value; (g) adjusting the quantity of the powder fill by an incremental amount; (h) weighing a number of tablets manufactured by the press after step (g) has been performed, computing the average weight thereof and recording the average weight as a second average weight; (i) recording the average value displayed by the controller as a second average value; (j) subtracting the first average weight from the second average weight and recording the absolute value of the difference thereof as a first difference; (k) subtracting the first average value from the second average value and recording the absolute value of the difference thereof as a second difference; (l) dividing the first difference by the second difference and recording the quotient thereof as a constant; (m) providing an upper tolerance representing the maximum weight which an acceptable tablet may weigh and a lower tolerance representing the minimum weight which an acceptable tablet may weigh; (n) dividing the upper tolerance by the constant, the quotient thereof being the value of the upper threshold; (o) dividing the lower tolerance by the constant, the quotient thereof being the value of the lower threshold; and (p) adjusting the upper and lower thresholds to correspond to the quotients obtained in steps (n) and (o) respectively.
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Specification