JP2011141224A - Combination balance and method of controlling conveying unit in the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve weighing accuracy in a combination balance. <P>SOLUTION: The information on the variance of hopper target weight as the target weight of an object 28 to be conveyed to a plurality of weighing hoppers 12 is set by an operation setting display 9, so that a controller 7 creates normal random numbers by making a normal distribution corresponding to the variance information match with the respective weighing hoppers 12 as the hopper target weight, and it controls a linear feeder 6 so that the weight of the object 28 to be weighed that is conveyed by a linear feeder pan 5 may amount to the weighing hopper 12 through a supply hopper 10 may be coincided with the hopper target weight. Thus, the weight of the object to be put into the respective hoppers 12 properly varies according to the normal distribution, so that the number of combinations approximating the target combination weight increases in the combination computation, thereby improving the combination weighing accuracy. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a combination weigher for weighing objects to be weighed, such as confectionery and fruits, and a method for controlling a conveyance unit for conveying the objects to be weighed in a combination weigher.

  An object to be weighed, such as confectionery, weighed with a combination weigher to have a predetermined weight is generally packaged by a packaging machine, for example.

  FIG. 9 is a diagram schematically showing a schematic configuration of a conventional combination weigher described in Patent Document 1. As shown in FIG.

  In this combination weigher, an object to be weighed is supplied from the supply device 30 to the central portion of the dispersion feeder 31, and the dispersion feeder 31 sends out the object to be weighed toward the periphery by vibration, and is installed radially around the dispersion feeder 31. Then, it is conveyed to a plurality of linear feeders 32.

  A vibration device is attached to the plurality of linear feeders 32, and each linear feeder 32 is vibrated to convey an object to be weighed and put into the plurality of supply hoppers 33. The plurality of supply hoppers 33 temporarily hold the objects to be weighed, open the discharge gate 34, and put the objects to be weighed into the weighing hoppers 35 disposed below the supply hoppers 33. In each weighing hopper 35, the weight of the object to be weighed is weighed by the weight sensor 36. By performing a combination calculation based on the measured value, a combination of the weighing hoppers 35 that is closest to or matches the combined target weight is obtained, and a discharge gate 37 of the weighing hopper 35 selected by this combination is obtained. Is opened to discharge the object to be weighed and put into the packaging machine 39 through the collecting chute 38.

JP 62-1113024 A

  In such a combination weigher, in order to improve the combination weighing accuracy, the weight of an object to be weighed that is conveyed by the linear feeder 32 and put into the weighing hopper 35 via the supply hopper 33 is important.

  As is well known, when the number of hoppers participating in the combination calculation is m, when m is an even number, an object to be weighed having a weight of “combination target weight / (m / 2)” is put into the hopper, and m is In the case of an odd number, if the object to be weighed has the weight “combination target weight ÷ ((m−1) / 2)” or the weight “combination target weight ÷ ((m + 1) / 2)”, Since the number of combinations close to the combination target weight increases, the combination weighing accuracy can be improved.

  For this reason, the target weight (hereinafter referred to as “hopper target weight”) of an object to be weighed that is transported by each linear feeder 32 and is put into each weighing hopper 35 via each supply hopper 33 is referred to as the above-mentioned combined target weight. The weight of the object to be weighed (hereinafter referred to as “predetermined hopper target weight”), which is conveyed by each linear feeder 32 and put into each weighing hopper 35, is the predetermined hopper target weight. Thus, the vibration amplitude and driving time of each linear feeder 32 are set to control the transport amount of the object to be weighed by each linear feeder 32.

  However, due to the amount of the objects to be weighed loaded on the dispersion feeder 31, the properties of the objects to be weighed, etc., the weight of the objects actually weighed into each weighing hopper 35 is the predetermined hopper. A slightly different value for the target weight is inevitable, and it may be biased toward the plus side (more) or minus side (less) with respect to the predetermined hopper target weight. It becomes difficult to make a combination close to the target combination weight, and the combination weighing accuracy is deteriorated.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a combination weigher with improved combination weighing accuracy.

  In order to achieve the above object, the present invention is configured as follows.

 (1) The combination weigher according to the present invention is arranged corresponding to each of the plurality of transport units for transporting the objects to be weighed, and weighs the weights of the objects to be weighed respectively transported from the respective transport units. A combination weigher that performs a combination calculation of the weights of the objects to be weighed by the weighing hopper, and sets a combination target weight that is a target weight of the combination calculation. A setting unit that sets information on a variation degree of a hopper target weight that is a target weight of an object to be weighed to each weighing hopper, and the combination target weight and information on the degree of variation set by the setting unit The hopper target weight according to the normal distribution is generated corresponding to each of the plurality of weighing hoppers, and the object to be weighed by the corresponding transport unit is generated according to the generated hopper target weight. And a control unit for controlling the Okuryou.

  The variation degree information is information indicating the degree of variation in the plurality of hopper target weights corresponding to the plurality of weighing hoppers, and the user may set information on the degree of variation that the user considers preferable.

  Since the information on the degree of variation is information indicating the degree of variation, it may be set as a standard deviation or variance.However, a preferable value of the hopper target weight, for example, the above-mentioned predetermined hopper target weight as a center (average) The spread boundary in the normal distribution curve may be set as the degree of variation. The center (average) of the normal distribution may be a weight other than the predetermined hopper target weight.

  The information on the degree of variation may be set as the degree of variation or the standard deviation itself, or the type of an object to be weighed, for example, if the object to be weighed is a confectionery, such as candy, potato chips, chocolate, etc. A table showing the correspondence between the type and the degree of variation and standard deviation is stored in the storage unit in advance, and the type of variation and standard deviation corresponding to the type are indirectly set by setting the type of the weighing object. You may be made to do.

  A combination target weight that is a target weight of the combination calculation is set by the setting unit, and since the number of hoppers participating in the combination calculation of the combination weigher is known, the number of combinations close to the combination target weight described above increases. A predetermined hopper target weight, which is a weight, can be determined.

  According to the combination weigher of the present invention, by setting the degree of variation in the hopper target weight, which is the target weight of the objects to be weighed to each of the plurality of weighing hoppers, as the “variation degree” information, Since the hopper target weight according to the normal distribution according to the degree is generated corresponding to each weighing hopper, the hopper target weight of each weighing hopper can be varied according to the normal distribution. For example, the predetermined hopper target described above It can vary according to the normal distribution with the weight as the center (average). Furthermore, since the transport amount of the objects to be weighed to each weighing hopper by each transport unit is controlled so as to achieve this dispersed hopper target weight, the objects to be weighed that are transported to and put into each weighing hopper The weight varies moderately according to the normal distribution, and the number of combinations close to the target combination weight is increased in the combination calculation, and the combination weighing accuracy is improved.

 (2) In a preferred embodiment of the combination weigher of the present invention, the generator generates a normal value of a standard deviation and an average value calculated based on the combination target weight, the degree of variation, and the number of hoppers participating in the combination calculation. A random number of distribution is generated as the hopper target weight.

  The average value is the weight of the center of the normal distribution, and is preferably the most preferable value as the hopper target weight, for example, the above-mentioned predetermined hopper target weight, and this predetermined hopper target weight is the combined target weight. And the number of hoppers participating in the combination calculation can be calculated as described above.

  The standard deviation is preferably defined according to the set degree of variation. For example, the standard deviation may be a value obtained by multiplying the average value by the degree of variation.

  According to this embodiment, it is possible to generate, as the hopper target weight, a standard deviation according to the degree of variation and a normal distribution random number according to the combination target weight and the number of hoppers participating in the combination calculation.

  (3) In another preferred embodiment of the combination weigher of the present invention, the transport unit is a vibration feeder that transports the object to be weighed by vibration, and the control unit controls the amplitude and driving time of each vibration feeder. Including a storage unit storing data indicating a correspondence relationship between at least one of them and a conveyance amount of the object to be weighed by the vibration feeder, and the control unit is stored in the storage unit according to the hopper target weight. Based on the data, at least one of the amplitude and driving time of the corresponding vibration feeder is controlled.

  The data indicating the correspondence between the amplitude of the vibration feeder and the transport amount of the object to be weighed, or the data indicating the correspondence between the driving time of the vibration feeder and the transport amount of the object to be weighed is an arithmetic expression indicating the correspondence It is preferable to store in the storage unit as a table.

  According to this embodiment, the control unit controls at least one of the amplitude and the driving time of the vibration feeder so that the amount of the object to be weighed to the weighing hopper becomes the hopper target weight generated according to the normal distribution. At that time, the control is performed based on data indicating a correspondence relationship between at least one of the amplitude and driving time of each vibration feeder stored in the storage unit and the conveyance amount of the object to be weighed by the vibration feeder.

  (4) In a preferred embodiment of the combination weigher of the present invention, based on the hopper target weight of each of the plurality of weighing hoppers generated by the generating unit and the weight of the object to be weighed measured by the corresponding weighing hopper. And a correction unit for correcting the data stored in the storage unit.

  The correction unit preferably determines whether or not correction is necessary every certain period or every certain number of weighings. For example, the hopper target weight in the past certain period or the past certain number of weighings. And the average value of the weights of the objects weighed by the weighing hopper, the necessity of correction is determined. When correction is necessary, the storage unit stores the correction value based on both average values. It is preferable to correct the stored data.

  According to this embodiment, if there is an error that needs to be corrected between the hopper target weight and the weight of the object to be weighed that is actually conveyed to the weighing hopper, the weighing hopper is actually operated by the correction unit. The data in the storage unit can be corrected so that the weight of the object to be weighed and weighed is matched with the hopper target weight, that is, the object to be weighed actually transported to the weighing hopper by the vibration feeder. Since the weight is feedback controlled so as to match the hopper target weight, the conveyance accuracy of the object to be weighed by the vibration feeder is improved, and thereby the combination weighing accuracy can be increased.

  (5) A method for controlling the transport unit in the combination weigher of the present invention includes a plurality of transport units for transporting an object to be weighed, and a target to be transported from each of the transport units. A control method for the transport unit in a combination weigher that includes a plurality of weighing hoppers for measuring the weight of the objects to be weighed, and performs a combined operation of the weights of the objects to be weighed by the weighing hoppers. A setting step for setting a combination target weight that is a weight, and setting information on a degree of variation in a hopper target weight that is a target weight of an object to be weighed to be conveyed to each of the plurality of weighing hoppers; A generating step of generating the hopper target weight according to a normal distribution in correspondence with the plurality of weighing hoppers based on the weight and the degree of variation information; and the generated hopper target weight Depending on, and a control step of controlling the conveyance amount of the objects to be weighed by the transport unit corresponding.

  According to the control method of the transport unit in the combination weigher of the present invention, the degree of variation in the hopper target weight, which is the target weight of the object to be weighed to be transported to each of the plurality of weighing hoppers, is set as “variation degree” information. Thus, since the hopper target weights according to the normal distribution according to this `` variation degree '' are generated corresponding to the respective weighing hoppers, the hopper target weights of the respective weighing hoppers can be varied according to the normal distribution, for example, The above-mentioned predetermined hopper target weight can be varied according to a normal distribution with the center (average). Furthermore, since the transport amount of the objects to be weighed to each weighing hopper by each transport unit is controlled so as to achieve this dispersed hopper target weight, the objects to be weighed that are transported to and put into each weighing hopper The weight varies moderately according to the normal distribution, and the number of combinations close to the target combination weight is increased in the combination calculation, and the combination weighing accuracy is improved.

  According to the present invention, by setting the degree of variation of the hopper target weight as “variation degree” information, a hopper target weight according to a normal distribution according to the “variation degree” is generated in correspondence with each weighing hopper. Therefore, the hopper target weight of each weighing hopper can be varied according to the normal distribution according to the setting. Furthermore, since the transport amount of the objects to be weighed to each weighing hopper by each transport unit is controlled so as to achieve this dispersed hopper target weight, the objects to be weighed that are transported to and put into each weighing hopper The weight varies moderately according to the normal distribution, and combinations near the target combination weight are increased in the combination calculation, and the combination weighing accuracy is improved.

FIG. 1 is a schematic diagram showing a schematic configuration of a combination weigher according to an embodiment of the present invention. FIG. 2 is a block diagram showing a schematic configuration of the combination weigher of FIG. FIG. 3 is a normal distribution diagram. FIG. 4 is a diagram illustrating the relationship between the amplitude of vibration of the linear feeder and the conveyance amount. FIG. 5 is a diagram illustrating the relationship between the driving time of the linear feeder and the carry amount. FIG. 6 is a flowchart for explaining the operation. FIG. 7 is a flowchart showing details of the control process of the linear feeder unit of FIG. FIG. 8 is a flowchart showing details of the table data correction processing of FIG. FIG. 9 is a schematic diagram showing a schematic configuration of a conventional combination weigher.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic diagram showing a schematic configuration of a combination weigher according to an embodiment of the present invention. The combination weigher of this embodiment has a conical top cone 3 that radially disperses the objects to be weighed 28 supplied from the supply device 1 by vibration, and a main feeder that vibrates the top cone 3 in the center of the upper portion of the apparatus. 4 is provided. The supply device 1 conveys an object to be weighed 28 supplied from a belt conveyor (not shown) by vibration and supplies it to the central portion of the top cone 3. In the top cone 3, the object to be weighed 28 supplied from the supply device 1 to the central portion thereof is conveyed toward the peripheral portion by vibration. Around the top cone 3, a plurality of linear feeder pans 5 for conveying the objects to be weighed 28 sent from the top cone 3 to the plurality of supply hoppers 10, and a plurality of linear feeders for vibrating the linear feeder pans 5, respectively. Feeders 6 are provided radially.

  A plurality of supply hoppers 10, weighing hoppers 12, and memory hoppers 15 are respectively provided below the peripheral edge of the linear feeder pan 5 and arranged circumferentially.

  Under the supply hopper 10 and the memory hopper 15, a discharge gate 11 and a gate 16 that can be opened and closed are provided, respectively. Further, at the bottom of the weighing hopper 12, there are provided discharge gates 13 and 14 that can be opened and closed on the memory hopper 15 side or the collecting chute 17 side, and the weighing object 28 is selected as the memory hopper 15 or the collecting chute 17 as appropriate. Can be supplied automatically.

  The supply hopper 10 receives the weighing object 28 fed from the linear feeder pan 5, and when the weighing hopper 12 disposed below it is empty, the discharge gate 11 is opened to load the weighing object 28 into the weighing hopper 12. To do. Each weighing hopper 12 is attached with a weight sensor 8 such as a load cell for measuring the weight of the object 28 in the weighing hopper 12, and a measured value from each weight sensor 8 is output to the control device 7.

  The plurality of linear feeder pans 5 and the plurality of linear feeders 6 that vibrate the respective linear feeder pans 5 constitute a plurality of transport units that transport and supply the objects to be weighed 28 to the corresponding weighing hoppers 12.

  The weighing hopper 12 can selectively discharge the object to be weighed 28 to the memory hopper 15 and the collecting chute 17 as described above. The memory hopper 15 is disposed obliquely below the weighing hopper 12, and the object to be weighed 28 is thrown from the weighing hopper 12 when empty. A combination of hoppers (hereinafter referred to as discharge hoppers) from which the objects to be weighed 28 are to be discharged is obtained from the plurality of weighing hoppers 12 and the memory hoppers 15 by combination calculation by the control device 7, and a discharge request signal is input from a packaging machine not shown If there is, the objects to be weighed 28 are discharged from the discharge hopper corresponding to the combination to the collecting chute 17 and further discharged to the packaging machine via the discharge chute 18 below.

  Above the top cone 3, for example, an ultrasonic level detector 2 for detecting the amount of the object to be weighed 28 is provided. The level detector 2 detects the layer thickness of the object to be weighed on the top cone 3, and the detection output is given to the control device 7. In the control device 7, based on the layer thickness of the weighing object 28 on the top cone 3 detected by the level detector 2, the supply device 1 is set so as to keep the weighing object 28 on the top cone 3 at a constant amount. Control.

  The operation setting indicator 9 is configured by using, for example, a touch panel and the like, a setting unit for operating the combination weigher and setting operation parameters thereof, a display unit for displaying an operation speed, a combination measurement value, and the like on a screen. It has.

  The control device 7 performs operation control of the supply device 1 and overall operation of the combination weigher, and also performs combination calculation. In the combination calculation, the weight of the object 28 in the weighing hopper 12 is weighed by the weight sensor 8, and the obtained weight is used as the weighing value of the weighing hopper 12. The weighing value of the weighing hopper 12 is stored in the storage unit of the control device 7, and when the object 28 in the weighing hopper 12 is put into the corresponding memory hopper 15, the stored weighing value is stored in the memory. Used as a measured value of the hopper 15. From the plurality of weighing hoppers 12 and the memory hopper 15, one combination of the above-described discharge hoppers in which the sum of the measured values of the objects to be weighed 28 falls within the allowable range with respect to the combination target weight is obtained.

  FIG. 2 is a block diagram showing a schematic configuration of a control system of the combination weigher in this embodiment. As shown in FIG. 2, the control device 7 includes an arithmetic control unit 20, a storage unit 21, an A / D conversion circuit unit 24, a gate drive circuit unit 25, and a vibration control circuit unit 26.

  The arithmetic control unit 20 has a built-in CPU, and has a function as a generation unit that generates a hopper target weight according to a normal distribution described later in association with each of the plurality of weighing hoppers 12. The storage unit 21 stores an operation program for the combination weigher, operation parameters to be set, and the like, and serves as a work area for operations on the CPU. The A / D conversion circuit unit 24 converts analog signals from the level detector 2 and each weight sensor 8 into digital signals and outputs the digital signals to the arithmetic control unit 20. The gate drive circuit unit 25 controls the opening and closing of the discharge gates 11; 13, 14; 16 of the supply hopper 10, the weighing hopper 12, and the memory hopper 15 based on a control signal from the arithmetic control unit 20. The vibration control circuit unit 26 controls each vibration operation of the supply device 1, the main feeder 4, and each linear feeder 6 based on a control signal from the arithmetic control unit 20. The arithmetic control unit 20 is connected to the operation setting display 9 so as to communicate with each other. Moreover, the calculation control part 20 is connected so that communication with the packaging machine which is not shown in figure is also possible.

  The control device 7 controls the operations of the supply device 1 and the entire combination weigher by the CPU of the arithmetic control unit 20 executing the operation program stored in the storage unit 21.

  In the combination weigher, it is necessary to set a large number of operation parameters for performing the operation as described above. The operator performs the setting using the operation setting display 9, and the value of the set operation parameter is calculated and controlled. Sent to the unit 20 and stored in the storage unit 21. The operation parameters include a combination target weight which is a target value in the combination calculation and an allowable range thereof, a vibration amplitude of the main feeder 4, a driving time of the main feeder 4 (one vibration duration time), and a vibration of the linear feeder 6. Amplitude, driving time of the linear feeder 6 (one vibration duration time), a measuring speed that is the number of bags packaged by a packaging machine per minute (that is, the number of times that the object to be weighed is discharged from the combination weigher per minute), etc. is there.

  In this embodiment, in order to increase the combination weighing accuracy, a hopper target weight, which is a target weight of an object to be weighed to be fed to each weighing hopper 12 via each supply hopper 10 through each linear feeder pan 5, is set. The number of combinations close to the combination target weight is increased so that the above-mentioned predetermined hopper target weight is moderately distributed according to the normal distribution, thereby increasing the number of combinations close to the target combination weight in the combination calculation. Yes.

  That is, in this embodiment, the operator operates the operation setting display 9 with the degree of preferable variation according to the normal distribution centered on the predetermined hopper target weight as the “variation degree” when setting the above-described operation parameters. And set.

  Based on the set “variation degree” and the combination target weight set as the above-described operation parameter, the control device 7 centers on a predetermined hopper target weight and follows a normal distribution according to the “variation degree”. The weight is generated corresponding to each weighing hopper 6.

  As an example of determining the predetermined hopper target weight, when the number of hoppers participating in the combination calculation is m as described above, when m is an even number, the weight “combination target weight ÷ (m / 2)”, Alternatively, when m is an odd number, the weight is “combination target weight value ÷ ((m−1) / 2)” or “combination target weight value ÷ ((m + 1) / 2)”. The hopper target weight for the hopper may be determined so that the number of hoppers selected by the combination is four or five. In this case, the predetermined hopper target weight is the combined target weight ÷ 4 or 5.

The number of hoppers participating in the combination calculation is defined by the combination scale.
In this embodiment, for example, if the number of weighing hoppers 12 is 10 and the number of memory hoppers 15 is 10, the number m of hoppers that can participate in the combination calculation is 20. In the case of a combination weigher that does not include the memory hopper 15, the number m of hoppers that can participate in the combination calculation is the number of weighing hoppers 12, and thus, for example, 10.

  Thus, by setting the combination target weight as the operation parameter, a predetermined hopper target weight is automatically calculated.

  In this embodiment, the operator sets the “degree of variation” as, for example, “%” as a boundary of the curve of a normal distribution centering on a predetermined hopper target weight. This “degree of variation” is, for example, such that the weight of an object to be weighed that is conveyed by each linear feeder pan 5 and put into each weighing hopper 12 has a preferable degree of variation around a predetermined hopper target weight. It is set based on experience and experiments.

  The “variation degree” is preferably set to a different value depending on the type of the object to be weighed, for example, “chocolate”, “potato chips”, and “飴” for confectionery.

  Based on the “variation degree” and the combination target weight set in this way, the arithmetic control unit 20 of the control device 7 uses a random number of a normal distribution according to the “variation degree” as the hopper of each of the plurality of weighing hoppers 12. Each linear weight that is generated as a target weight and vibrates the linear feeder pan 5 so that the weight of an object to be weighed and fed into each weighing hopper 12 by each linear feeder pan 5 becomes the corresponding hopper target weight. Control the feeder 6.

  As a result, the hopper target weights of the plurality of weighing hoppers 12 can be varied according to the set “variation degree” around the predetermined hopper target weight according to the normal distribution. The weight of the object to be weighed in and transported will vary moderately from the weight before and after the specified hopper target weight, and there will be many combinations close to the target combination weight in the combination calculation, and the combination weighing accuracy Will improve.

  Here, generation of the hopper target weight according to the normal distribution will be described.

  The normal distribution has a probability density function expressed by the following equation.

Here, μ is an average, and σ ² is variance, and this normal distribution is represented as N (μ, σ ² ).

  If the weight value is x1, x2,... Xn, the average weight value is

  At this time,

The called dispersion (precisely the sample variance), if the population is sufficiently large sample size of the finite, as an estimate of variance sigma ²

  Is called unbiased dispersion. The expected value of unbiased variance is equal to the variance of the population. The positive square root of this variance or unbiased variance is the standard deviation.

Therefore, if the average weight and standard deviation of the weighing object of the weighing hopper 12 are known,
Normal distribution data of the hopper target weight of the weighing hopper 12 can be obtained by the probability density function.

 In this embodiment, as described above, the “variation degree” is set and input from the operation setting display unit 9 as an operation parameter in advance. This “variation degree” designates the degree of dispersion of the hopper target weight of the n weighing hoppers 12.

 In this embodiment, the “variation degree” can be expressed by the following equation.

“Degree of variation” = standard deviation / predetermined hopper target weight Based on this predetermined hopper target weight and “degree of variation”, the standard deviation can be calculated by the following equation.

Standard deviation = “variation degree” × predetermined hopper target weight The predetermined hopper target weight is the center of variation as described above, and is an average weight value of the objects to be weighed put into a plurality of weighing hoppers. Can be considered. That is,
Average weight value = predetermined hopper target weight In this way, the standard deviation (= “variation” × predetermined hopper target weight) and the average weight value (= predetermined hopper target weight) are known. The weight can be generated as a random number according to a normal distribution.

  This normal random number can be generated by converting a uniform random number by the Box-Muller Transform method.

  That is, normal random numbers r1 and r2 in the range from 0 to less than 1 are substituted into the following equation based on the Box-Muller method to calculate normal random numbers.

Here, r1 and r2 are uniform random values by an Rnd function for generating uniform random numbers,
r1 = Rnd (1)
r2 = Rnd (1)
It is.

By multiplying the normal random number by the above standard deviation and adding the average weight value,
A normal random number according to the normal distribution represented by the following formula can be generated as a hopper target weight corresponding to each weighing hopper 12.

  The hopper target weight generated in this way is, for example, as shown in the normal distribution diagram of FIG. 3 in which the horizontal axis represents the weight and the vertical axis represents the number. Distributed symmetrically. Therefore, the hopper target weights corresponding to the respective weighing hoppers 12 are stochastically varied in the weights before and after the predetermined hopper target weight, and many combinations close to the target combination weight are continuously maintained. become.

  The arithmetic control unit 20 of the control device 7 generates the hopper target weight as described above, and the transport amount of the object 28 to be transported to the weighing hopper 12 by the linear feeder pan 5 becomes the generated hopper target weight. Thus, the linear feeder 6 that vibrates the linear feeder pan 5 is controlled.

  Here, a correspondence relationship between the amplitude of the vibration of the linear feeder 6 and the driving time that is the duration of the vibration and the transport amount of the workpiece to be transported by the linear feeder pan 5 will be described.

  FIG. 4 is an example of a characteristic diagram showing a correspondence relationship between the amplitude (frequency) of vibration of the linear feeder 6 during a certain driving time and the transport amount (g) of the object to be weighed.

  As a method of changing the amplitude of vibration of the linear feeder 6, phase control and voltage control are well known. In FIG. 4, the horizontal axis represents the phase angle or voltage value when the amplitude is maximum, and the vertical axis represents the conveyance amount of the object to be weighed. In this embodiment, the amplitude of vibration can be set to 100 levels from 1 to 100. As shown in FIG. 4, the conveyance amount and the amplitude value do not change linearly.

  FIG. 5 is an example of a characteristic diagram showing a correspondence relationship between the driving time (ms) of the linear feeder 6 and the transport amount (g) of the object to be measured at a certain amplitude.

  The drive time is one continuous vibration time of the linear feeder 6. The correspondence between the drive time and the carry amount changes linearly when the correspondence between the amplitude and the carry amount in FIG. 4 is compared.

  In this embodiment, the storage unit 21 of the control device 7 stores characteristic data indicating the correspondence between the amplitude of the linear feeder 6 and the transport amount of the object to be measured, the driving time of the linear feeder 6 and the transport amount of the object to be weighed. Is stored in advance as, for example, an arithmetic expression or a table indicating the correspondence. Since the amount of the object to be weighed is slightly different for each linear feeder 6, it is preferable to store individual characteristic data for each linear feeder 6.

  Further, in this embodiment, the driving time and amplitude determined so that the transport amount of the object to be weighed to each weighing hopper 12 becomes the above-mentioned predetermined hopper target weight are a part of the above-described operation parameters. The driving time and amplitude of each linear feeder 6 are set in advance by an operator who operates the operation setting display 9.

  Then, the control device 7 vibrates with the drive time of the linear feeder 6 being set so that the conveyance amount of the object to be weighed by each linear feeder 6 matches the hopper target weight generated as described above. Only the amplitude is controlled.

  In other words, in this embodiment, the calculation control unit 20 of the control device 7 sets only the amplitude of the linear feeder 6 so that the amount of the object to be weighed by the linear feeder 6 becomes the hopper target weight generated as a normal random number. I try to control it. Since only the amplitude is controlled in this way, the driving time is not increased and the metering speed is not decreased unlike the case of controlling the driving time.

  As described above, the hopper target weight according to the normal distribution is generated corresponding to each weighing hopper 12 around the predetermined hopper target weight, and the weight of the object to be weighed conveyed to each weighing hopper 12 is generated. Since the amplitude of the vibration of the corresponding linear feeder 6 is controlled so as to obtain the target hopper weight, each weighing hopper 12 has a weight to be weighed that is moderately distributed according to a normal distribution centering on the predetermined hopper target weight. Will be input. This increases the number of combinations close to the target combination weight in the combination calculation, and improves the combination weighing accuracy.

  Furthermore, in this embodiment, due to the amount of the object to be weighed loaded on the top cone 3, the property of the object to be weighed, etc., the weight of the object to be weighed actually put into the weighing hopper 12 is When it is different from the hopper target weight, it is as follows so that it can be corrected.

  That is, the average value of the weights of the objects actually put into the weighing hopper 12 during a certain period or every certain number of weighings is calculated, and the average value of the generated hopper target weights is calculated. When the absolute value of the difference between the two exceeds the allowable value, it is assumed that there is an error to be corrected between the weight of the object to be weighed actually put into the weighing hopper 12 and the hopper target weight. A correspondence relationship between the amplitude of the linear feeder 6 and the transport amount of the object to be weighed is stored in the storage unit 21 of the control device 7 so that the weight of the object to be weighed becomes the hopper target weight. Correct the characteristic data.

  As a result, the amplitude of the vibration of the linear feeder 6 is controlled based on the corrected characteristic data, and an error between the weight actually put into the weighing hopper 12 and the generated hopper target weight is reduced. As a result, the weighing accuracy is improved.

  FIG. 6 is a flowchart for explaining the above-described operation of the combination weigher of this embodiment.

  First, the control device 7 controls the ON / OFF of the supply device 1 based on the detection output of the level detector 2 that detects the amount of the object to be weighed on the top cone 3, so that the object to be weighed becomes the top cone 3. Supply (step S1). The control device 7 controls the main feeder 4 that vibrates the top cone 3 to disperse the objects to be weighed on the top cone 3 and supplies them to the linear feeder pan 5 (step S2).

  The control device 7 controls the linear feeder 6 that vibrates the linear feeder pan 5, vibrates the linear feeder pan 5 corresponding to the empty supply hopper 10, and supplies an object to be weighed on the linear feeder pan 5 to the empty supply. Supply to the hopper 10 (step S3). In this step S3, the weight of the object to be weighed that is conveyed by the linear feeder pan 5 and fed into the weighing hopper 12 via the supply hopper 10 becomes the hopper target weight generated according to the normal distribution as described above. The amplitude of vibration of the linear feeder 6 is controlled to control the transport amount of the object to be weighed. Details of the processing in step S3 will be described later.

  The control device 7 controls the discharge gate 11 of the supply hopper 10, opens the discharge gate 11 of the supply hopper 10 corresponding to the empty weighing hopper 12, and transfers the object to be measured to the empty measurement hopper 12. Supply (step S4). When an object to be weighed is supplied to the empty weighing hopper 12 in this way, the corresponding weight sensor 8 measures the weight of the object to be weighed supplied to the weighing hopper 12 and sends the measured value to the control device 7 ( Step S5). The control device 7 controls the discharge gates 13 and 14 of the weighing hopper 12, opens the discharge gate 13 of the weighing hopper 12 corresponding to the empty memory hopper 15, and removes the object to be weighed from the empty memory hopper 15. (Step S6). In the case of a combination weigher that does not include the memory hopper 15, this step S6 is omitted.

  In this embodiment, the weighing value measured by the weight sensor 8 of the weighing hopper 12, that is, the weight of the object actually put into the weighing hopper 12, and the hopper target weight generated according to the normal distribution as described above. Are used to correct the characteristic data indicating the correspondence between the amplitude of the linear feeder 6 and the transport amount of the object to be weighed (step S7). Details of the correction processing in step S7 will be described later.

  The control device 7 performs a combination calculation based on the weights of the objects to be weighed supplied to the weighing hopper 12 and the memory hopper 15, and selects an optimum combination (step S8). Thereafter, when a discharge request signal is input from the packaging machine, the control device 7 gives a command to the weighing hopper 12 and the memory hopper 15 of the optimum combination to discharge the objects to be weighed (step S9), and then to step S1. Return. Thereafter, by repeating the same weighing cycle as described above, an amount of an object to be weighed that satisfies a certain condition is discharged to the packaging machine.

  FIG. 7 is a flowchart showing details of the control process of the linear feeder in step S3 of FIG. Here, it is assumed that the number of weighing hoppers 12 is n, and therefore, the number of linear feeder pans 5 and linear feeders 6 that transport an object to be weighed into the weighing hopper 12 is n.

  First, the number of the n linear feeders 6 is set to 1 (step S201), and the hopper target weight of the weighing hopper 12 corresponding to the number 1 linear feeder 6 is generated as described above using a normal distribution random number. (Step S202).

  Next, the vibration amplitude of the linear feeder 6 is set so that the weight of the object to be weighed conveyed to the weighing hopper 12 by the linear feeder 6 becomes the hopper target weight generated in step S202. The linear feeder 6 is set (step S203), and the process proceeds to step S204. As a result, the linear feeder 6 having the number vibrates the linear feeder pan 5 with the drive time set in advance as the operation parameter and the amplitude set in step S203, and conveys the object to be weighed.

  In step S204, the generated hopper target weight is cumulatively added as the input weight to the weighing hopper 12 for the correction processing in step S7 of FIG. 6 described above, and the cumulative added value is divided by the number of additions to hopper target weight. The number of the linear feeder 6 is incremented by 1 (step S205), and it is determined whether or not the number of the linear feeder 6 is n + 1 (step S206). When it is not n + 1, the process returns to step S202, and the same processing is performed for the next linear feeder 6.

  Thus, the hopper target weight of each of the plurality of weighing hoppers 12 is generated according to the normal distribution, and the weight of the object to be weighed that is transported by the linear feeder 6 and put into each of the weighing hoppers 12 becomes the hopper target weight. Since the amplitude of the linear feeder 6 is controlled, the weight of the object to be weighed put into each weighing hopper 12 varies moderately around the predetermined hopper target weight, so that the weight in the combination calculation is the target weight. The number of combinations close to the combination weight increases and the combination weighing accuracy improves.

  FIG. 8 is a flowchart showing details of correction processing of characteristic data indicating the correspondence between the amplitude of the linear feeder 6 and the transport amount of the object to be weighed in step S7 of FIG.

  First, the number of the weighing hopper 12 is set to 1 (step S701), and the weighing value of the weighing hopper 12 is cumulatively added (step S702), whether or not it is a correction timing, that is, a predetermined cumulative number, for example, It is determined whether or not the weighing cycle has reached 100 times (step S703). If it is not the correction timing, the process proceeds to step S708.

  When the correction timing is reached, for example, the average value of the weights of the last 100 weighing objects that are actually thrown into the weighing hopper 12 by dividing the accumulated value of the weighing value, for example, 100 times, by the loading number of 100 times. An input actual value that is a value is calculated (step S704).

  On the other hand, for example, an average value of the past 100 times of the hopper target weight of the weighing hopper 12 calculated in step S204 of FIG. 7 is calculated, and this calculated value is subtracted from the input actual value calculated in step S704. It is determined whether or not the absolute value of the calculated value is smaller than a predetermined allowable value (step S705). If the absolute value is smaller, the process proceeds to step S707 because no correction is necessary. As this allowable value, for example, a value close to zero is set in advance.

  If it is not smaller than the allowable value in step S705, it is assumed that there is an error between the target hopper weight and the weight of the object to be weighed actually put into the weighing hopper 12, and the linear feeder 6 is set to eliminate this error. The characteristic data of the correspondence relationship between the amplitude of the vibration and the transport amount of the object to be weighed is corrected (step S706).

  Specifically, when the weight of the object to be weighed actually put into the weighing hopper 12 is smaller than the target hopper weight, that is, when the conveyance amount by the linear feeder 6 is small, the amplitude of the characteristic data is corrected to be larger. On the other hand, when the weight of the object actually put into the weighing hopper 12 is larger than the hopper target weight, that is, when the conveyance amount by the linear feeder 6 is large, the amplitude of the characteristic data is corrected to be smaller. Such correction is performed, for example, by correcting a coefficient of an arithmetic expression indicating the characteristic data or a table value.

  Next, in step S707, the above-described average value of actual charging, the average value and cumulative value of the hopper target weight are initialized, the number of the weighing hopper 12 is incremented by 1 (step S708), and the number of the weighing hopper 12 is increased to n + 1. It is determined whether or not (step S709). When n + 1 is reached, the process ends. When it is not n + 1, the process returns to step S702 and the same processing is performed for the next weighing hopper 12.

  In this way, when the weight of the object to be weighed actually put into the weighing hopper 12 and the hopper target weight are different and the difference exceeds the allowable value, the characteristic data used for the control of the linear feeder 6 is corrected. Then, since feedback control is performed so that the weight of the object to be weighed put into the actual weighing hopper 12 becomes the hopper target weight, the combination weighing accuracy is improved.

(Other embodiments)
In the above-described embodiment, only the amplitude of the linear feeder 6 is controlled. However, as another embodiment of the present invention, the driving time may be controlled. In this case, the driving time and the transport amount of the object to be weighed What is necessary is just to correct | amend the characteristic data of these correspondence. Further, both the amplitude and the driving time may be controlled. In this case, the characteristic data of the correspondence relationship between the amplitude and the transport amount of the object to be weighed, and the driving time and the transport amount of the object to be weighed It is sufficient to correct at least one of the characteristic data of the correspondence relationship.

 The present invention is useful for improving a combination weigher, and in particular, a combination weighing accuracy thereof.

DESCRIPTION OF SYMBOLS 3 Top cone 4 Main feeder 5 Linear feeder pan 6 Linear feeder 7 Control apparatus 8 Weight sensor 9 Operation setting display 10 Supply hopper 12 Weighing hopper 15 Memory hopper 20 Operation control part 21 Memory | storage part 26 Vibration control circuit part

Claims (5)

A plurality of transport units for transporting the objects to be weighed, and a plurality of weighing hoppers arranged to correspond to the respective transport units and for weighing the weight of the objects to be weighed respectively transported from the respective transport units, A combination weigher that performs a combination calculation of the weights of objects to be weighed by a weighing hopper,
A setting unit that sets a combination target weight that is a target weight of the combination calculation, and sets information on a variation degree of a hopper target weight that is a target weight of an object to be weighed to be transported to each of the plurality of weighing hoppers;
Based on the information on the combination target weight and the degree of variation set by the setting unit, a generation unit that generates the hopper target weight according to a normal distribution corresponding to each of the plurality of weighing hoppers;
In accordance with the generated hopper target weight, a control unit that controls the conveyance amount of the object to be weighed by the corresponding conveyance unit;
A combination weigher characterized by comprising: The generation unit generates, as the hopper target weight, a random number of a normal distribution of a standard deviation and an average value calculated based on the combination target weight, the degree of variation, and the number of hoppers participating in the combination calculation.
The combination weigher according to claim 1. The transport unit is a vibration feeder that transports the object to be weighed by vibration,
The control unit includes a storage unit that stores data indicating a correspondence relationship between at least one of the amplitude and driving time of each vibration feeder and a conveyance amount of an object to be weighed by the vibration feeder,
The control unit controls at least one of the amplitude and the driving time of the corresponding vibration feeder based on the data stored in the storage unit according to the hopper target weight.
The combination weigher according to claim 1 or 2. The data stored in the storage unit is corrected based on the hopper target weight of each of the plurality of weighing hoppers generated by the generation unit and the weight of the object to be weighed measured by the corresponding weighing hopper. The correction part
The combination weigher according to claim 3 provided. A plurality of transport units for transporting the objects to be weighed, and a plurality of weighing hoppers arranged to correspond to the respective transport units and for weighing the weight of the objects to be weighed respectively transported from the respective transport units, A method for controlling the transport unit in a combination weigher that performs a combination calculation of the weights of objects to be weighed by a weighing hopper,
A setting step of setting a combination target weight that is a target weight of the combination calculation, and setting information of a variation degree of a hopper target weight that is a target weight of an object to be weighed to be conveyed to each of the plurality of weighing hoppers;
Generating the hopper target weight according to a normal distribution in correspondence with the plurality of weighing hoppers based on the set combination target weight and the information on the degree of variation;
A control step of controlling the transport amount of the object to be weighed by the corresponding transport unit according to the generated hopper target weight;
The control method of the conveyance part in the combination weigher characterized by including.

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