Control method for controlling the operating state of a press machine

Abstract

A control method for controlling the operating state of a rotary press (1) for forming tablets (100), wherein the rotary press (1) is a rotary compression turret (2), and includes a die table (3) on which a plurality of dies (4) are provided along the circumferential portion of the rotary compression turret (2), a plurality of lower punches (6) and a plurality of corresponding upper punches (5) associated in pairs with each die (4), the lower punches (6) and the upper punches (5) each having a substantially cylindrical body with contact ends into which a lower compression roller (12) and an upper compression roller (11) respectively abut, and a supply station (7), the control method for controlling the operating pressure of the lower compression roller (12) and the upper compression roller (11) The system comprises a control system (20) for controlling the operation, and includes a detection step in which the supply of powder (50) to the die (4) is blocked during the detection step so that there is at least one empty die (4a), the lower punch (6) and / or upper punch (5) are moved toward the at least one empty die (4a) by the respective lower and / or upper compression means, and a pressure resistance value is measured by the detection means (14) as the value of the pressure applied by the respective lower and / or upper compression means to the corresponding lower punch (6) and / or upper punch (5) as they are moved inside the at least one empty die (4a); and an evaluation step in which the pressure resistance value is processed by the control system (20) to generate a signal relating to the punch operation state.

Description

Technical Field

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[0001] The present invention relates to a control method for controlling the operating state of a press for producing tablets, pellets, pills for pharmaceutical, cosmetic, food, and chemical applications by compressing powders or granules. In particular, the present invention relates to a method of operating a rotary press in an evaluation step of mechanical operation.

[0002] A rotary press comprising a compression turret, the compression turret rotating around a vertical axis, angularly distributed, and arranged along the rim of the compression turret or on its circumferential part at equal intervals, and formed by a die table or plate provided with a plurality of dies or through holes arranged holes arranged to receive powders or granules distributed at an appropriate supply station.

[0003] The turret further comprises a plurality of upper punches and lower punches associated with each die and vertically moved by cams and compression rollers during rotation of the turret.

[0004] The lower punch forms, together with the die, respective seats or housings suitable for receiving the powder at the supply station. The upper punch and the lower punch compress the powder introduced into the die to produce a tablet, and then the tablet is removed from the die table by the appropriately raised lower punch and conveyed to an outfeed chute.

[0005] The various steps for manufacturing the tablet are performed during at least a part of one rotation of the continuously rotating compression turret.

[0006] During the machine assembly step or maintenance or format change step, the operator proceeds with the installation of one or more punches into the machine. In this step, the operator verifies the correct positioning of one or more punches mounted on the turret. However, the positive outcome of this step is strongly influenced by the operator's skill and knowledge. For example, errors during the assembly step, such as not inserting all punches into their respective turret housings or incorrectly installing punches, can lead to problems such as the possible dispersion of powder within the machine, machine malfunction or damage, resulting in undesirable production stoppages that require restoring proper function.

[0007] Furthermore, the punch, which is slidably associated with the die, must slide smoothly between itself and the die during each manufacturing cycle without generating excessive friction that could lead to premature wear of the associated mechanical components or potential failure within a series of manufacturing cycles. Friction that is not maintained within certain limits can also lead to an increase in the temperature of the mechanical components involved, which can adversely affect the powder in contact with them.

[0008] The sensor is provided to detect the compressive force of the powder by monitoring its quality during tablet manufacturing.

[0009] A drawback of these rotary presses, which use one or more sensors to monitor the compressive force applied to the powder by the punches during tablet deformation, is the lack of operational status information for each punch. In fact, if a pressure value outside the acceptable range is measured, the signal indicates an error not directly attributable to that particular punch. Furthermore, these machines do not provide information about the correct assembly of the punches in the correct locations that took place before the manufacturing step, nor do they provide information about whether all punches were installed. [Overview of the project]

[0010] The object of the present invention is to improve known tablet presses, in particular rotary presses having a compression turret equipped with a die and a punch, and means for monitoring the compression force.

[0011] Another object of the present invention is to provide a method for detecting the presence or absence of a punch associated with a given die, before a manufacturing step, i.e., after an assembly or maintenance step of a tablet press machine, in order to avoid contamination by dust dispersed on the die table.

[0012] A further objective is to prevent any punches that are improperly mounted or of the wrong size from causing damage to the press machine.

[0013] A first aspect of the present invention provides a control method for controlling the operating state of a rotary tablet press machine as described in claim 1. [Brief explanation of the drawing]

[0014] The present invention can be better understood and implemented with reference to the accompanying drawings illustrating exemplary and non-limiting embodiments. [Figure 1] This is a schematic diagram of a rotary press machine according to the present invention. [Figure 2] Figure 1 is a schematic diagram of a rotary press machine during the detection step. [Figure 3] This is an enlarged view of the compression station of a rotary press machine according to a different embodiment. [Figure 4] Figure 2 is a schematic diagram of a rotary press machine with a punch missing. [Modes for carrying out the invention]

[0015] Referring to Figure 1, a rotary press 1 according to the present invention is shown, which is configured to manufacture tablets, pellets, and pills by compressing powders or granules for pharmaceutical, cosmetic, food, or chemical applications.

[0016] The rotary press 1 includes a compression turret 2 that rotates around a vertical axis of rotation (not shown), the compression turret 2 includes a die table 3, the compression turret 2 is provided with a plurality of dies 4 along part of its or circumferential rim, a plurality of upper punches 5, and a plurality of corresponding lower punches 6 associated with each die 4. These upper punches 5 and lower punches 6 are movable to compress the powder 50 introduced into the die 4 in order to manufacture tablets 100, pellets, or pills.

[0017] The die 4 is a through cavity formed in the die table 3 that, in cooperation with the lower punch 6, is fed powder 50 and then compressed to form a seat or housing that forms a tablet 100.

[0018] The rotary press 1 includes a filling means for filling the die and a supply station 7 configured to distribute the powder 50 to be compressed into the die 4, and at least one compression station 8 or main compression station provided with upper compression rollers 11 and lower compression rollers 12 adapted to operate upper punches 5 and lower punches 6, respectively, along the compression direction A inside each die 4 to compress the powder 50 distributed into the die 4 and form tablets 100. The lower punches 6 and upper punches 5 each have a substantially cylindrical body with contact ends that the lower compression rollers 12 and upper compression rollers 11, respectively, contact.

[0019] In the embodiment shown in the figure, the compression direction A is substantially vertical, i.e., parallel to the axis of rotation of the compression turret 2. For simplicity, only the downward arrow A is shown in the figure, but obviously the powder 50 is also compressed by the lower punch 6.

[0020] The compression station 8 also includes an actuator 15 connected to and acting on the upper compression roller 11, which holds the upper compression roller 11 in a fixed operating position so that the upper compression roller 11 restrains the upper punch 5 and applies a compressive force Fc to the powder 50 in each die 4. The compression station 8 may further include an additional actuator 15 connected to and acting on the lower compression roller 12, as shown in Figure 3, which holds the lower compression roller 12 in a fixed operating position so that the lower compression roller 12 restrains the lower punch 6 and applies an additional compressive force Fc to the powder 50 in each die 4. Alternatively, the lower compression roller 12 may be rotatably mounted on the support frame 13 of the rotary press 1, as shown in Figures 1, 2 and 4.

[0021] During the operation of the rotary press machine 1, when the upper punch 5 moving within each die 4 is operating in a state where it is resisting the upper compression roller 11 with a pressure resistance of Fc or less, the actuator 15 holds the upper compression roller 11 in a fixed operating position along the compression direction A. In this way, as the compression turret 2 rotates, the upper punch 5 is progressively engaged by the upper compression roller 11 and pushed into the die 4 by the upper compression roller 11 to compress the powder 50 against the lower punch 6 below.

[0022] The rotary press machine 1 also includes a detection means 14 for measuring the pressure resistance of the punch against the compressive force Fc as the punch moves along the compression direction A.

[0023] As will be better described below, the rotary press machine 1 is operated according to an operating method that is intended to monitor its correct operation. More precisely, the described operating method is intended to detect the presence of all punches 5, 6 on the compression turret 2 and to verify their correct assembly / operation.

[0024] During the production of tablets, a step of supplying powder 50 into die 4 through the supply station 7 is executed. In this step, the lower punch 6 associated with each die 4 to be filled operates as a bottom wall, forming a temporary chamber where the powder 50 to be compressed arrives. The amount of powder 50 occupying die 4 depends on the positioning of the lower punch 6 within die 4 and the size of die 4.

[0025] It is clear that the term powder 50 also refers to granules and the like.

[0026] Subsequently, when the powder 50 is supplied to die 4, a step of compressing the powder 50 is provided. Compression of the powder 50 is performed by moving each lower punch 6 and upper punch 5 by applying the compression force Fc, and the compression force Fc depends on the positions of the lower compression roller 12 and upper compression roller 11 where the abutting ends of the lower punch 6 and upper punch 5 respectively abut.

[0027] One aspect of the method according to the present invention is provided by a detection step in which, as shown in FIG. 2, the powder 50 supplied into die 4 by the supply station 7 is blocked, i.e., interrupted, so that there is no powder 50 in die 4, obtaining at least one empty die 4a. Next, the movement of the lower punch 6 and upper punch 5 is actuated. It is clear that the moved upper punch 5 and lower punch 6 are associated with one or more empty dies 4a into which no powder 50 is supplied. While the pair of lower punch 6 and upper punch 5 are moved towards the empty die 4a, a pressure resistance value is measured by the detection means 14 as the pressure value applied to the corresponding punches 5, 6 by the respective lower and upper compression means in a state where there is no powder 50 to be compressed inside each empty die 4a.

[0028] In the specific embodiment shown in FIG. 2, the lower compression means and the upper compression means respectively correspond to the lower compression roller 12 and the upper compression roller 11.

[0029] According to a particular embodiment in which the compression means corresponds to a compression roller, in the detection step, the detection means 14 is arranged as a plurality of sensors associated with the lower compression roller 12 and the upper compression roller 11. According to one aspect of the present invention, the detection means 14 is connected to the actuator 15. Furthermore, the detection means 14 may comprise at least one load cell. According to another embodiment, the detection means 14 may comprise one or more encoders and / or one or more piezoelectric sensors. Generally, the detection means 14 may comprise one or more sensors of known types suitable for measuring pressing force and converting the measured pressing force into associated electrical signals.

[0030] According to a further aspect of the present invention, the detection means 14 can be connected to any component connected to the lower compression rollers 12 and / or upper compression rollers 11, in a configuration that enables measurement of the pressure resistance values ​​applied to the corresponding lower punches 6 and / or upper punches 5 by the respective lower compression rollers 12 and / or upper compression rollers 11.

[0031] According to a particular embodiment, the compression means can be arranged on the machine 1 as an auxiliary compression means along the lower compression roller 12 and the upper compression roller 11.

[0032] This detection step can be performed while stationary, i.e., without rotating the compression turret 2. Alternatively, it can be done by moving the turret 2 at a speed that is very limited compared to the normal speed during tablet manufacturing, for example, at a speed of about 1% of the normal manufacturing speed. Furthermore, the speed at which the punches 5 and 6 move along the compression direction A is also preferably very limited compared to the normal speed during tablet manufacturing, for example, at about 1% of the normal manufacturing speed.

[0033] When the detection step is performed by rotating the compression turret 2, the rotational motion of the compression turret 2 causes the lower punch 6 and the upper punch 5 to translate parallel and perpendicular to the compression direction A, so that these punches come into contact with the compression means (lower compression roller 12 and / or upper compression roller 11), and the pressure resistance value is measured by the detection means 14.

[0034] If the detection step is performed in a stationary state, the compression means may be moved toward each punch. More specifically, by one or more actuators, the compression means is moved toward the respective contact ends of the lower punch 6 or the upper punch 5. The motion given to the compression means can be along a horizontal axis, and therefore parallel to the die table 3, or perpendicular to it, and parallel to the compression direction A. According to a further embodiment, both the compression means and the compression turret 2 can be moved together during the detection step.

[0035] According to the present invention, an evaluation step is performed in which the withstand pressure value is processed by the control system 20 to generate a signal correlated with the punch operation state.

[0036] The control system 20 processes the acquired pressure resistance values ​​by comparing them with appropriate predetermined thresholds to determine the relative states of the lower punch 6 and / or upper punch 5.

[0037] According to another aspect of the present invention, the evaluation step includes a data storage substep of storing withstand voltage values ​​obtained during a plurality of detection steps for a particular empty die 4a in a data storage unit.

[0038] Preferably, in the data storage substep, the withstand pressure values ​​acquired between multiple detection steps are aggregated with data relating to the corresponding empty die 4a on which they were measured and the moment of measurement, generating aggregated data to be stored in the data storage unit.

[0039] The data storage unit can be included in the control system 20.

[0040] Alternatively, the data storage unit may be a separate unit from the control system 20. The data storage unit can be configured as a known type of physical memory and / or as a cloud system.

[0041] It is clear that by repeating the detection and evaluation steps N times on a specific empty die 4a, N withstand pressure values ​​measured over time can be obtained. The change in withstand pressure during the multiple detection steps determines the trend of withstand pressure over time for the specific empty die 4a.

[0042] Preferably, in the evaluation step, the withstand pressure value obtained during the detection step N can be compared with one or more of the N-1 withstand pressure values ​​previously obtained and stored in the data storage unit, where N is the total number of withstand pressure measurements performed on a particular empty die 4a.

[0043] According to a particular embodiment, the signal, which correlates with the punching state, includes a command to stop the rotary press 1 so that the operator can quickly intervene in the machine.

[0044] The signal generated by the control system 20 may be an alarm signal, such as a missing punch alarm, as shown in Figure 4, where the withstand voltage is less than a first predetermined value. Alternatively, if the withstand voltage is higher than a second predetermined value, the signal may be a punch malfunction alarm. The first predetermined value is smaller than the second predetermined value.

[0045] According to a further embodiment, the signal generated by the control system 20 may be a warning signal different from the alarm signal.

[0046] According to another aspect of the present invention, in the detection step, the trend of the withstand voltage value for a particular empty die 4a is also evaluated, and the control system 20 generates an alarm signal to intervene before the withstand voltage value falls outside a predetermined tolerance window if the trend is intended to fall outside that tolerance window.

[0047] The predetermined tolerance window is based on a reference pressure value that represents the optimal pressure resistance value under correct mechanical operating conditions. The predetermined tolerance window has an amplitude such as ±10%, preferably ±5%, and more preferably ±2% of the reference pressure resistance value.

[0048] This warning signal is different from the missing punch alarm and the punch malfunction alarm.

[0049] According to a further aspect of the present invention, prior to the detection and evaluation steps, an assembly step is performed in which one or more lower punches 6 and / or upper punches 5 are associated with the compression turret 2. This assembly step can be performed, for example, during the replacement or resizing of one or more punches for maintenance work on the machine 1. In other circumstances, this assembly step can be performed during the initial assembly of the machine 1, when the punches are first attached to the compression turret 2. After the punch assembly, the detection and evaluation steps are performed to verify the correct assembly. In this way, it is possible to detect and evaluate the correct assembly performed by the operator who attached one or more punches to the machine 1. More precisely, it is possible to detect whether all punches have been attached to the machine 1 before proceeding to tablet manufacturing, and it is also possible to detect whether all punches associated with the compression turret 2 have been correctly attached. [Aspect 1] A control method for controlling the operating state of a rotary press (1) for forming tablets (100), wherein the rotary press (1) is a rotary compression turret (2) comprising: a die table (3) on which a plurality of dies (4) are provided along the circumferential portion of the rotary compression turret (2); a plurality of lower punches (6) and a plurality of corresponding upper punches (5) paired with each die (4), wherein the lower punches (6) and the upper punches (5) each have substantially cylindrical bodies with contact ends that contact a lower compression roller (12) and an upper compression roller (11), respectively; and a supply station (7) including a filling means for filling the dies (4), wherein the rotary compression turret (2) comprises the following during tablet manufacturing: - The step of supplying powder (50) into the die (4) by the supply station (7), -The process involves compressing the powder (50) supplied into the die (4) by moving the respective lower punches (6) and upper punches (5), and applying a compressive force (Fc) along the vertical compression direction (A) to the contact ends of the lower punches (6) and upper punches (5) by bringing them into contact with the lower compression roller (12) and upper compression roller (11), respectively, thereby compressing the powder (50) supplied into at least one die (4) to manufacture a tablet. A control method further comprising: a detection step in which the supply of the powder (50) to the die (4) is prevented so as to have at least one empty die (4a), the lower punch (6) and / or upper punch (5) are moved toward the at least one empty die (4a) by their respective lower and / or upper compression means, and a pressure resistance value is measured via a detection means (14) as the value of the pressure applied by their respective lower and / or upper compression means to the corresponding lower punch (6) and / or upper punch (5) as they are moved within the at least one empty die (4a); and an evaluation step in which the pressure resistance value is processed by a control system (20) to generate a signal correlated with the punch operating state. [Aspect 2] The control method according to Embodiment 1, wherein in the evaluation step, the signal generated by the control system (20) is an indication of punch defects when the withstand pressure value is less than a first predetermined pressure value. [Aspect 3] The control method according to embodiment 1 or 2, wherein in the evaluation step, the signal generated by the control system (20) is an indication of a malfunctioning punch when the withstand value exceeds a second predetermined pressure value. [Aspect 4] The control method according to embodiment 3, which is dependent on embodiment 2, wherein the first predetermined pressure value is lower than the second predetermined pressure value. [Aspect 5] The control method according to embodiment 1 or 2, wherein in the detection step, the detection means (14) comprises a plurality of sensors associated with the lower and / or upper compression means. [Aspect 6] The control method according to embodiment 5, wherein the plurality of sensors include at least load cells. [Aspect 7] The control method according to any one of embodiments 1 to 6, wherein the upper compression means and the lower compression means correspond to the upper compression roller (11) and the lower compression roller (12), respectively. [Aspect 8] The control method according to any one of embodiments 1 to 7, wherein in the detection step, the lower punch (6) and / or the upper punch (5) are moved toward the at least one empty die (4a) by the respective lower compression means and / or the upper compression means by rotating the compression turret (2). [Aspect 9] The control method according to any one of embodiments 1 to 8, wherein, prior to the detection step and the evaluation step, one or more lower punches (6) and / or one or more upper punches (5) are installed in the compression turret (2). [Aspect 10] The control method according to any one of embodiments 1 to 9, wherein in the evaluation step, the signal correlated with the punch operation state includes a command to stop the rotary press (1). [Aspect 11] The control method according to any one of embodiments 1 to 10, wherein the evaluation step includes a data storage substep in which withstand voltage values ​​obtained during a plurality of detection steps for a specific empty matrix (4a) are stored in a data storage unit. [Aspect 12] The control method according to any one of embodiments 1 to 11, wherein in the detection step, the trend of the withstand voltage value for a specific empty die (4a) is also evaluated, and the control system (20) generates a warning signal to intervene before the withstand voltage value falls outside a predetermined tolerance window if the trend is intended to fall outside a predetermined tolerance window.

Claims

1. A control method for controlling the operating state of a rotary press (1) for forming tablets (100), wherein the rotary press (1) is a rotary compression turret (2) comprising: a die table (3) on which a plurality of dies (4) are provided along the circumferential portion of the rotary compression turret (2); a plurality of lower punches (6) and a plurality of corresponding upper punches (5) paired with each die (4), wherein the lower punches (6) and the upper punches (5) each have substantially cylindrical bodies having contact ends into which a lower compression roller (12) and an upper compression roller (11) respectively abut; and a supply station (7) including a filling means for filling the dies (4), wherein the rotary compression turret (2) comprises the following during tablet manufacturing: - A step of supplying powder (50) into the die (4) by the supply station (7), - The process involves compressing the powder (50) supplied into the die (4) by moving the respective lower punches (6) and upper punches (5), and applying a compressive force (Fc) along the vertical compression direction (A) to the contact ends of the lower punches (6) and upper punches (5) by bringing them into contact with the lower compression roller (12) and upper compression roller (11), respectively, thereby compressing the powder (50) supplied into at least one die (4) to manufacture a tablet. A control method further comprising: a detection step in which the supply of the powder (50) to the die (4) is prevented so as to have at least one empty die (4a), the lower punch (6) and / or the upper punch (5) are moved toward the at least one empty die (4a) by the respective lower and / or upper compression means, and a pressure resistance value is measured via a detection means (14) as the value of the pressure applied by the respective lower and / or upper compression means to the corresponding lower punch (6) and / or the upper punch (5) as they are moved within the at least one empty die (4a); and an evaluation step in which the pressure resistance value is processed by a control system (20) to generate a signal correlated with the punch operating state.

2. The control method according to claim 1, wherein in the evaluation step, the signal generated by the control system (20) is an indication of punch defects when the withstand pressure value is less than a first predetermined pressure value.

3. The control method according to claim 1 or 2, wherein in the evaluation step, the signal generated by the control system (20) is an indication of a malfunctioning punch when the withstand value exceeds a second predetermined pressure value.

4. The control method according to claim 3, in which the first predetermined pressure value is lower than the second predetermined pressure value, as described in claim 2.

5. The control method according to claim 1 or 2, wherein in the detection step, the detection means (14) comprises a plurality of sensors associated with the lower and / or upper compression means.

6. The control method according to claim 5, wherein the plurality of sensors include at least load cells.

7. The control method according to claim 1 or 2, wherein the upper compression means and the lower compression means correspond to the upper compression roller (11) and the lower compression roller (12), respectively.

8. The control method according to claim 1 or 2, wherein in the detection step, the lower punch (6) and / or the upper punch (5) are moved toward the at least one empty die (4a) by the respective lower compression means and / or the upper compression means by rotating the rotary compression turret (2).

9. The control method according to claim 1 or 2, wherein one or more lower punches (6) and / or one or more upper punches (5) are installed on the rotary compression turret (2) before the detection step and the evaluation step.

10. The control method according to claim 1 or 2, wherein in the evaluation step, the signal correlated with the punch operation state includes a command to stop the rotary press (1).

11. The control method according to claim 1 or 2, wherein the evaluation step includes a data storage substep in which withstand voltage values ​​obtained during a plurality of detection steps for a specific empty matrix (4a) are stored in a data storage unit.

12. The control method according to claim 1 or 2, wherein in the detection step, the trend of the withstand pressure value for a specific empty die (4a) is also evaluated, and the control system (20) generates a warning signal to intervene before the withstand pressure value falls outside a predetermined tolerance window if the trend is intended to fall outside a predetermined tolerance window.

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