JPH0436800B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] This invention converts the change in compression force during compression molding into an electrical signal and inputs it to a setting machine, and then compares the set value (control limit) set in the setting machine with the compression force during molding. A rotary powder compression molding machine such as a rotary tablet making machine that compares the change in force and automatically adjusts the amount of powder filled into the mortar hole based on the exceeded value if the control limit is exceeded. This relates to a weight control method for molded products, and more specifically, in such a weight control method for molded products, equipment such as rods and compression rolls expands or contracts due to changes in room temperature or heat generated by the molding machine. The present invention relates to a method for controlling the weight of a molded product in a rotary powder compression molding machine that is not affected by variations in the thickness of the molded product or changes in compression pressure that occur due to this. [Prior Art] Generally, the weight of a molded product changes depending on the density of powder in the hopper, the amount of powder supplied from the hopper to the feedstock, and the size of the powder, and the physical properties of these powders, etc. Therefore, it is difficult to continuously produce homogeneous molded products. Therefore, as disclosed in Japanese Patent Publication No. 45-16085 (Japanese Patent Application No. 41-37865), changes in the load applied to compression rolls or punches during compression molding have been measured using electrical strain meters. Convert to change of
A relay and a prime mover are activated by a change in the amount of electricity exceeding a limit, and the heavy rail is raised and lowered by the operation of the prime mover, and the lower punch above is caused to move up and down by the lifting and lowering of this heavy rail. Molding in a powder compression molding machine in which the volume of the mortar determined by the height of the lower punch is increased or decreased by changing the height of the lower punch, thereby adjusting the amount of powder supplied to the mortar. There is a method for automatically adjusting the weight of the product.
Publication No. 48319 (Japanese Unexamined Patent Publication No. 48-57889) and Tokuko Sho
As disclosed in Publication No. 58-54920 (Japanese Unexamined Patent Publication No. 57-165200), the compression force during compression molding is converted into an electrical signal, which is input into a multi-stage setting device with predetermined control limits for comparison. Then, the amount of powder supplied to the mortar is adjusted based on the control limit of each setting device, and the
In addition to the above, the method of Publication No. 54920 includes methods for controlling molded products in a powder compression molding machine, such as comparing the weight of a molded product sampled with a scale with a reference weight and changing the electrical signal level input to a setting device. There are ways to adjust the weight. [Problem to be solved by the invention] Although it is possible to produce a homogeneous molded product even with such conventional technology, it is possible to produce a molded product with a certain degree of homogeneity. Temperature changes cause the upper punch, lower punch, compression roll, etc. to expand or contract, and as a result, the compression force during compression molding changes and the thickness of the molded product changes even though the weight does not change. That is, as the temperature rises, the length of the upper and lower punches increases, the diameter of the compression roll increases, and the distance between the compression rolls decreases, which is ultimately determined by the distance between the compression surfaces of the upper and lower punches. The compression interval changes, and even when the same amount of powder is compressed, the compression force changes by the change in the compression interval, and the thickness of the molded product also changes. Therefore, due to the change in compression pressure due to this temperature, the weight control performed by measuring the compression force described above changes the amount of powder filled into the mortar hole even though the actual weight of the molded product does not change. As a result, weight errors occurred in the molded product, and the thickness of the molded product was also inconsistent. Also, as in the above-mentioned Japanese Patent Publication No. 58-54920,
A scale that samples the molded product to measure the true weight of the molded product and corrects the electrical signal level (change in compression pressure) based on the true weight also has problems in operation. However, no consideration was given to the effects of changing temperatures, and there were problems in that accurate weight control was not possible and the thickness of the molded product was not constant. The influence of temperature changes on compression pressure (compression load), etc. in a tablet manufacturing machine will be explained below using experimental values. Table 1 shows the number of times when the punch diameter is 8 mm and the powder filling depth is 5.45 mm when manufacturing corner planar tablets using powder consisting of 98% β-lactose, 1% stearin magnesium, and 1% talc. 1 and the number of times is 2
After that, raise the lower pestle in 0.05mm increments until 10 times.
5.00mm, and each time from 1st to 10th
Take out 50T (T is the number of tablets) and empty it.
The graph shows the relationship between the weight per 1T and tableting pressure (compression molding pressure) after measuring 10T each three times. According to this, the compression ratio is 2 (the ratio of the filled volume to the compressed tablet volume). The tableting pressure was 1340 kg when the number of times was 1.

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[Table] Explanation of Table 3 The distance between the lower surface of the upper roll and the upper surface of the lower roll is 270 mm.
Fixed to. The total of the upper and lower punches is 266.7mm, which is the difference from the above 270mm.
3.3 mm is a value that takes into account the expansion dimension of the tablet taken out after compression molding. Looking at the change in compression pressure due to thermal expansion as an example, H ₁ = dimensional difference of the upper punch, H ₂ = dimensional difference of the lower punch, H ₃
= Dimensional difference between the upper and lower rolls, h = filling depth for one time, Kg = pressure difference for one time, when the compression ratio is 2, pressure difference = 2Kg (H ₁ + H ₂ + H ₃ ) / h - Kg・_H2 /h=2
×50×(0.023+0.03+0.025)/0.05−50×0.03/0.05
= 126Kg In Table 1, for example, when the tableting pressure is 1030Kg and the average weight is 202mg, the pressure will increase by 126Kg due to thermal expansion, and if this pressure increase is considered as an increase in weight and the weight adjustment is corrected, then 197mg. Even though the true tablet weight has not changed and only the thickness has become thinner, the resulting tablets are 5 mg less than the actual tablet weight. [Means for Solving the Problems] In order to solve such problems, according to the present invention, changes in compression force during compression molding in powder molding are converted into load electrical signals and input into a multistage setting device. In a method for controlling the weight of a molded product in a rotary powder compression molding machine, which adjusts the amount of powder filled into the mortar hole based on the electric signal exceeding the control limit set in the setting device, the method includes weighing the molded product. The change from the basic weight of the proper product is converted into a weight electrical signal, and the quantity rail is adjusted based on the signal so that the weight of subsequent molded products is correct, and the multistage setting device described above is adjusted based on the molding load at that time. , the molded product is weighed again and compared with the basic weight, and if the weight change is in the same direction as the weight change, the height of the compression roll is adjusted. A method for controlling the weight of a molded article in a compression molding machine is provided. In the above configuration, the setting value set in the setting device is determined by sampling the electric signal representing the change in compressive force a suitable number of times to calculate the load standard deviation of the appropriate product, and calculating the load standard deviation of the appropriate product based on the standard deviation. The setting value of each setting device can be calculated and determined based on the reference value of the setting device. In this case, the setting value (control limit) of the setting device was previously set using the electrical signal of the compressive load when the product was judged to be good based on the thickness and weight of the test compression molded product. This method can be automatically determined by anyone in a short period of time, compared to the previous method, which required highly skilled skills and time on the part of the operator. [Operation] The above technical means operates as follows. As mentioned above, it can be seen that depending on the material of the punch and compression roll, there is a certain degree of expansion and contraction as the temperature changes. That is, due to temperature changes, the distance between the upper and lower punches changes, and thereby the compression pressure generated during molding changes even when the weight of the molded product is correct. Therefore, in addition to the weight control that is performed by inputting the load electrical signal in normal compression molding into a setting device and comparing it with the set value, the molded product is sampled as appropriate and the weight of the molded product is detected and used as a weight electrical signal. . Then, if the weight of the molded product changes by more than a certain amount when compared with the electrical signal of the basic weight of the proper product set in advance, the weight should first be corrected based on the electrical signal of the change. Adjust portion rail. Next, the setting values of the multistage setting devices are set based on the molding load of the molded product with the weight of the molded product corrected. That is, the setting values are corrected to obtain a molded product with an appropriate weight in that state (a state including the influence of the physical properties of the powder, etc.). Then, sample the molded product again, weigh it, and compare it with the basic weight. If the weight change is in the same direction as the weight change above, there is a change in the powder filling volume, that is, an effect due to temperature changes such as expansion and contraction of the punch. It can be determined that there is a change in the weight, and the magnitude of the influence of temperature change, that is, the necessary adjustment amount of the compression roll height can be determined based on the amount of weight change. [Example] An example of the present invention will be described with reference to the drawings.
Reference numeral 4 denotes a mortar mounting board (rotary disc in a rotary powder compression molding machine) on which a mortar 3, which is a molding die, is installed; the upper part of a lower punch 5 is inserted into this mortar 3; 3 is filled with powder material, and the upper punch 2 and the lower punch 5 are pressurized vertically by the pressure mechanism of the upper roll 1 and the lower roll 6, and the powder in the mortar 3 is compressed and molded. ing. 7 is a load electric converter such as a load cell, and the load electric converter is provided in contact with either the upper roll 1 or the lower roll 6, for example, the support of the upper roll 1, and its output end is connected to an amplifier. It is connected to a signal processing device 8 consisting of, etc., and converts changes in compression load during powder compaction into electrical signals. The output end of the signal processing device 8 is connected to the setting devices 10, 11, 12, 13, 14, and 15 of each stage, respectively, and is also connected to the arithmetic processing device 9. This arithmetic processing device 9 calculates the standard deviation by processing the maximum value of the peak value of the sampled molding pressure, for example, in conjunction with the temperature change by a temperature sensor installed indoors or in the molding machine, either arbitrarily or periodically. Then, based on this standard deviation, calculate a reference value for the setting device, and based on the reference value, calculate each setting value, which is the control level of the setting devices 10, 11, 12, 13, 14, and 15 at each stage. and decide. Then, the arithmetic processing device 9 and the setting device 10 of each stage,
11, 12, 13, 14, 15 are respectively
They are connected as SET1, 2, 3, 4, 5, 6, and the respective set values determined above are automatically transmitted to the setters 10, 11, 12, 13, 14,
15 is input. Reference numeral 21 denotes a weighing device for measuring the weight of the compression-molded molded product, and the weighing device 21 is connected to the arithmetic processing device 9.
The weight change of the molded product sampled at predetermined time intervals is converted into a weight electrical signal and input to the processing device 9. When the weight of the molded product is greater or less than a predetermined amount compared to the basic weight stored in the processing device 9, the processing device 9 issues a quantity rail adjustment signal and outputs a quantity rail adjustment signal to correct the weight difference. The setting values of the setters 10, 11, 12, 13, 14, and 15 of each stage are set based on the molding load of the molded product whose weight has been corrected. Then, the processing device 9 Weigh the molded product again, compare the weight change with the weight change above, and operate the lifting device for the compression rolls in the same direction, for example, if it is judged to be lighter than the basic weight again (if it is lighter, increase the distance between the rolls). ). Of course, if it is determined by weighing that the weight is within the basic weight, the weight will not be weighed again. To explain the setting devices at each stage, the setting device 10 sets the upper limit of the control limit range, and uses the set value outputted as SET1 from the arithmetic processing device 9 and the electrical signal formed by the signal processing device 8. It compares a certain output P and outputs OUT1 when this output P exceeds the above set value. The setting device 11 is for setting the upper limit exclusion level, and compares the set value output as SET2 and the output P as described above, and outputs OUT2 when the output P exceeds the above set value. OUT3 is output when this occurs consecutively for a specified number of times or more. The setting device 12 is for setting the start of control on the upper limit side, and compares the set value outputted as SET3 and the output P as described above, and if the output P exceeds the above set value a separately determined number of times consecutively. This outputs OUT4. The setting device 13 sets the start of control on the lower limit side, and compares the set value outputted as SET4 from the arithmetic processing device 9 with the output P, which is an electric signal generated by shaping from the signal processing device, and sets this output. OUT5 is output when P exceeds the above set value for a separately determined number of consecutive times. The setting device 14 is for setting the lower limit rejection level, and compares the set value outputted as SET5 and the output P as described above, and outputs OUT6 when the output P exceeds the above set value. OUT7 is output when this occurs consecutively for a predetermined number of times or more. The setting device 15 is for setting the lower limit of the control limit range, and compares the set value outputted as SET6 with the output P as described above, and outputs OUT8 if this output P exceeds the above set value. It is something. The above-mentioned OUT1 and OUT8 output the reason for stopping the machine as a message (display), and also output to the machine control system to stop the machine. OUT3 and OUT7 output the reason for stopping the machine as a message (display), and also output to the machine control system to stop the machine. The above-mentioned OUT2 and OUT6 output the reason for rejecting the molded article (product) as a message (display), and also output to the machine control system to reject the molded article. The above-mentioned OUT4 and OUT5 output the reason for adjusting the filling amount as a message (display), and also control the weight adjustment mechanism such as a weight rail that determines the height of the lower pestle 5 in order to adjust the amount of powder filled in the mortar 3. It is output to the filling amount adjustment system to be controlled. The arithmetic processing unit 9 not only performs sampling at any time before operation, such as when switching product types, but also performs sampling at regular time intervals, at a fixed number of molding times, or during molding compression during operation based on an arbitrary external signal. It is possible to perform sequential sampling, calculate the standard deviation of the new state, and automatically reset the setting value of the setting device of each stage, and also to automatically reset the setting value of the setting device of each stage. The average load value 16, the maximum load value 17, the minimum load value 18, the standard deviation 19, the coefficient of variation 20, and the weight of the weighed molded product (not shown), the amount of change from the basic weight, the amount of adjustment of the compression roll, etc. It can be displayed on a display or recorded and output. 26 is a lifting device for the lower roll 6;
6 is formed from a pulse motor 22, a worm 23, a worm gear 24, and a threaded rod 25.
The lower roll 6 is moved up and down by the rotation of the motor 22, and the compression interval between the upper punch 2 and the lower punch 5 is changed. It should be noted that the present invention is not limited to the above-mentioned embodiments. For example, the weighing may be carried out by weighing one molded product individually or by measuring the deviation weight of a plurality of molded products at once. Weighing for each sampling may be performed twice in total, and even if the weight of the molded product is normal in the first weighing, it may be weighed again for accuracy improvement or confirmation. Furthermore, when the compression roll height is adjusted, the setting value of the setting device may be returned to the original value immediately, or the setting value may be set based on a new molding load, which is optional. Furthermore, even if it is determined that adjustment of the compression roll height is necessary, it is optional to add a confirmation means such as adjusting only when there is a temperature change of more than a certain level compared to changes in room temperature or molding machine temperature. be. [Effects of the Invention] As explained above, the present invention can eliminate variations in the thickness of molded products and weight adjustment errors caused by temperature changes in a method for controlling the weight of molded products, and can produce molded products with higher precision. It has the effect of being able to provide the following.

[Brief explanation of drawings]

The drawing shows a method for adjusting the weight of a molded product in a rotary powder compression molding machine according to the present invention.
FIG. 1 is an explanatory diagram showing one embodiment. In the drawing, 1 is the upper roll, 2 is the upper punch, 3 is the mortar, 4 is the mortar mounting plate, 5 is the lower punch, 6 is the lower roll, 7
8 is a signal processing device, 9 is an arithmetic processing device, 10, 11, 12, 13, 14, 15
16 is a setting device, 16 is an average load value, 17 is a maximum load value, 18 is a minimum load value, 19 is a standard deviation, 20 is a coefficient of variation, 21 is a conversion processor, and 26 is a lifting device.

Claims (1)

[Claims] 1. Converting the change in compression force during compression molding in powder molding into a load electrical signal and inputting it to a multi-stage setting device, based on the electrical signal exceeding the control limit set in the setting device. In a method for controlling the weight of a molded product in a rotary powder compression molding machine that adjusts the amount of powder filled into a mortar hole, the molded product is weighed, the change from the basic weight of the proper product is converted into a weight electrical signal, and the signal is Adjust the quantity rail based on this to ensure that the weight of the subsequent molding machine is correct, set the setting value of the multi-stage setting device above based on the molding load at that time, weigh the molded product again, and compare it with the basic weight. A method for controlling the weight of a molded product in a rotary powder compression molding machine, characterized in that the height of the compression roll is adjusted when the weight change of the perilla is in the same direction as the weight change. 2. Convert the change in compressive force during compression molding in powder molding into a load electrical signal, sample the electrical signal appropriately several times to calculate the load standard deviation, and calculate the load standard deviation based on the standard deviation. The reference value of the setting device is set by calculating and determining each setting value of the multi-stage setting device based on the calculated reference value, and the filling is performed by comparing the load electric signal from subsequent molding with each setting value. In a method for controlling the weight of a molded product in a rotary powder compression molding machine that automatically controls the amount of powder, etc., the molded product is weighed, the change from the basic weight of the appropriate product is converted into a weight electrical signal, and the amount is determined based on the signal. Adjust the rail so that the weight of subsequent molded products is correct, set the setting value of the multistage setting device above based on the molding load at that time, weigh the molded product again, compare it with the basic weight, and check the weight change. A method for controlling the weight of a molded product in a rotary powder compression molding machine, characterized in that the height of the compression roll is adjusted when the weight change is in the same direction as the weight change.