JP2003240629A - Combination weighing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To operate continuously without generating a defective product even if the single article mass is fluctuated at the lot switching time of an object to be weighed. <P>SOLUTION: A mass distribution calculation means 41 receives the mass from a mass calculation means 26 and the number of articles from a conversion means 27 of the number of articles during weighing operation, and determines a mass distribution of the object to be weighed supplied at present, namely, the mean value A' of the single article mass and a standard deviation σ'. A conversion information renewal means 43 calculates new conversion information from the mean value A' and the standard deviation σ' calculated by the mass distribution calculation means 41, and renews the conversion information set in the conversion means 24 of the number of articles by the calculated conversion information. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention supplies an object to be weighed to a plurality of weighing units, selects a combination of the number of objects to be weighed based on the weighing result of each weighing unit, and selects the selected objects to be weighed. In a combination weighing device that discharges all at once,
The present invention relates to a technique for enabling continuous operation without causing defective products even when there is a change in the single quality amount such as when the lot of the object to be weighed is switched.

[0002]

2. Description of the Related Art Conventionally, a combination weighing device has been used for collecting articles having individually different masses within a preset number range.

In this type of combination weighing device, a plurality of weighing units, such as hoppers and scales, detect the masses of the objects to be weighed, and the respective masses are converted into the number to obtain the number.
From the combinations of the objects to be weighed, select the combination whose combined number falls within the preset target number range,
The objects to be weighed selected for the combination are discharged from the weighing section and collected.

As described above, in the combination weighing device that sets the number of combinations, it is necessary to check and set the parameters required for the number conversion in advance.

In order to perform accurate conversion from mass to number, the average value and standard deviation that determine the distribution of the mass (single quality quantity) of each object to be weighed are required.

That is, as shown in FIG. 9, if the mass of each object to be weighed follows a normal distribution, and let A be the average value of the single quality quantities obtained by measurement and its standard deviation be σ, The distribution of one mass is almost 99. within the range of A ± 3σ.
There is a 7% chance of entering. The mass distribution of the m objects to be weighed is approximately 99.7 within the range of mA ± 3σm ^1/2.
Enter with a percentage probability. Note that 4σ may be used instead of 3σ, and in this case, the probability becomes higher.

Therefore, the mass range for each number is previously calculated as When m = 1, A ± 3σ When m = 2, 2A ± 3σ2^1/2 When m = 3, 3A ± 3σ3^1/2 ...... If set to, the mass obtained from the output signal of the measuring instrument
By checking which is in the above range,
Can be detected.

Further, as shown in FIG.
The upper limit of the distribution of m objects and the lower limit of the distribution of m + 1 objects to be weighed
Intersects mA + 3σm^1/2= (M + 1) A-3σ (m + 1)
^1/2 That is, A = 3σ {m^1/2+ (M + 1)^1/2} Is when.

Therefore, the number m of the objects to be weighed is equal to the number m +
1 can be distinguished from the range in which A> 3σ {m ^1/2 + (m + 1) ^1/2 } is satisfied, and the number can be correctly converted from the mass by 3σ {m ¹ from the average value A of the single quality amount. ^{/ 2} + (m
Up to the maximum value L of the number m in which +1) ^1/2 } becomes smaller.

As described above, when the number conversion from the mass obtained by weighing the object to be weighed is performed, the average value and the standard deviation of the single quality amount are required.

For this reason, in the past, the objects to be weighed were placed one by one on a static balance to obtain the single quality quantity, the average value and the standard deviation were calculated, and the average value and the standard deviation were calculated for each piece. The mass range is calculated, and this is set in the number conversion unit of the combination weighing device.

[0012]

However, as described above, the mass of each of the objects to be weighed is measured by the static balance before performing the combination weighing, and the average value and the standard deviation thereof are calculated, and the mass of each piece is further measured. Even if the range is calculated and set in the combination weighing device and the operation is started, if the average of the single quality quantity of the objects to be weighed or the amount of variation changes due to switching of the lot of the objects to be weighed, etc. Cannot be performed correctly, resulting in defective products.

For this reason, it is necessary to stop the operation of the weighing device and perform the above work each time the lot is switched, which causes a problem that the efficiency of the line is significantly reduced.

The present invention solves this problem and allows continuous operation without causing defective products even if there is a fluctuation in the average or variation in the single quality amount of the objects to be weighed when the lots are switched. It is an object of the present invention to provide a combination weighing device that can be used.

[0015]

In order to achieve the above object, the combination weighing device according to claim 1 of the present invention sets in advance the respective masses of the objects to be weighed which are detected by being supplied to a plurality of weighing units. In the combination weighing device for converting each to a number based on the converted information, selecting a combination of objects to be weighed based on the converted number, and discharging the objects to be weighed selected in the combination from the weighing unit, A mass distribution calculating means (41) for calculating an average value and a standard deviation of single quality quantities of the objects to be weighed based on the masses of the objects to be weighed detected by the plurality of weighing units during operation and the number conversion results thereof. A conversion information updating means (43) for updating the conversion information necessary for the number conversion based on the average value and the standard deviation calculated by the mass distribution calculating means is provided.

A combination weighing device according to a second aspect of the present invention is the combination weighing device according to the first aspect, wherein the average value and the standard deviation calculated by the mass distribution calculating means,
It has a distribution comparison means (45) for comparing the average value and the standard deviation on which the current conversion information is based, and the conversion information updating means updates the conversion information according to the comparison result of the distribution comparison means. The feature is to do.

A combination weighing device according to a third aspect of the present invention is the combination weighing device according to the second aspect, wherein the supply means (2) for automatically supplying the objects to be weighed to the plurality of weighing units.
1, 22), and the mass distribution calculating means is configured such that, when the distribution comparing means determines that the difference between at least one of the average value and the standard deviation is greater than or equal to a reference value, the plurality of weighing units. The feeding means is instructed to feed at least one specified weighing unit one by one, and the average value and standard deviation of the single quality quantities are calculated from the weighing result of the specified weighing unit. The conversion information update means is configured to update the current conversion information with conversion information determined by the average value and the standard deviation calculated by the mass distribution calculation means for the specific weighing unit. I am trying.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 show a configuration of a combination weighing device 20 to which the present invention is applied.

In FIG. 1, a plurality of Ps (P is, for example, 10)
Feeder 21 ₁ to 21 of _P is to convey the objects to be weighed which have received at one end from the supply line (not shown) to substantially horizontally the other end, respectively, the supply hopper 22 _1-22 disposed below
Supply appropriate amount to _P respectively.

The supply hoppers 22 _{1 to} 22 _P are formed such that the bottoms thereof are openable and closable so that the objects to be weighed can be accommodated and discharged, and receive the objects to be weighed supplied from the feeders 21 _{1 to} 21 _P , respectively. Weighing hoppers 23 ₁ to 23 arranged below
Supply to _P.

Like the supply hoppers 22 _{1 to} 22 _P , the respective weighing hoppers 23 ₁ to 23 _P are formed such that their bottoms are openable and closable so that the objects to be weighed can be accommodated and discharged.
It is supported by 4 _{1 to} 24 _P , and each weighing device 24 _{1 to} 24
_P is a weighing value signal s _{1 to} s corresponding to the load of the corresponding weighing hopper and the object to be weighed accommodated in the weighing hopper.
_P is output to the mass calculating means 26 described later.

The collective discharge device 25 collectively discharges the objects to be weighed discharged from the weighing hopper.

As shown in FIG. 2, the mass calculating means 2
6, weighing signals _s 1 ~ from the meter ₂₄ 1 to 24 _P
Each of the weighing hoppers 2 receives the s _P and subtracts the weight of the weighing hopper itself (the weighing value signal when it is empty) from the weighing value.
The mass g _{1 to} g of the objects to be weighed stored in 3 ₁ to 23 _P
Calculate _P.

The mass calculating means 26 constitutes a weighing section together with a weighing hopper and a weighing device corresponding to the weighing hopper. Here, it is assumed that the mass calculating means 26 is commonly included in a plurality of weighing sections. May be provided for each weighing device, or the weighing device itself may be provided with the above-described mass calculation function.

The number conversion means 27 is calculated by the mass calculation means 26 on the basis of conversion information preset by a conversion information setting means 37, which will be described later, for example, information indicating the relationship between the mass range and the number. mass _g 1 to g _P respectively converted to the number _m 1 ~m _P.

The combination selecting means 30 is a mass calculating means 26.
The number m of the mass _g 1 to g _P of the objects to be weighed in each weighing hopper ₂₃ 1-23 _P calculated, each weighing hopper ₂₃ 1-23 objects to be weighed _P obtained by the number conversion means 27 by
_{1 to} m _P and a preset target mass range G based on
Select a combination of weighing hoppers that fall within the range of a to Gb and the target number range Ma to Mb.

The weighing hopper control means 31 controls the weighing hopper 2
Among 3 ₁ to 23 _P , the weighing hoppers selected by the combination by the combination selecting means 30 are opened and closed, and the objects to be weighed stored in the weighing hoppers are discharged to the collective discharge device 25.

The supply hopper control means 32 controls the supply hopper 2
Of the 2 _{1 to} 22 _P , the supply hopper corresponding to the empty measurement hopper opened and closed by the measurement hopper control means 31 is opened and closed to supply the object to be weighed to the measurement hopper.

The feeder control means 33 includes a feeder 21 ₁
21 _P , the feeder corresponding to the empty supply hopper opened and closed by the supply hopper control means 32 is driven to supply a new object to be measured to the supply hopper.

The above-mentioned feeders 21 ₁ to 2
1 _P , supply hoppers 22 _{1 to} 22 _P, and a supply hopper control means 32 and a feeder control means 33 for controlling the opening and closing of these.
Is a supply means for supplying the objects to be weighed to the respective weighing hoppers 23 ₁ to 23 _P.

The parameter setting section 35 includes target amount setting means 36 for setting a target mass range and a target number range necessary for selecting a combination of the combination selecting means 30 before operation,
It has a conversion information setting means 37 for initializing the conversion information indicating the relationship between the mass range and the number necessary for the number conversion of the number conversion means 27 before operation.

The target amount setting means 36 displays a character string or the like for inputting the target mass range and the target number range on the display device 38, and the target mass range Ga to Gb and the target input by the operation of the operation unit 39. The number range Ma to Mb is set in the combination selection means 30.

Further, the conversion information setting means 37 displays a character string or the like instructing the input of the initial value of the conversion information necessary for the number conversion on the display device 38, and the conversion information input by the operation of the operation unit 39. Is initialized in the number conversion means 27.

The conversion information updating unit 40 includes the mass calculating means 26.
Based on each mass of the objects to be weighed calculated by the above and the number output from the number conversion means 27 for the mass, new conversion information suitable for converting the number of objects to be weighed currently supplied is obtained. , Update the conversion information currently used.

The conversion information updating unit 40 receives the mass from the mass calculating means 26 and the number from the number converting means 27 during the weighing operation, and determines the mass distribution of a single piece of the object to be weighed currently supplied. A mass distribution calculating means 41 for calculating the average mass and its standard deviation, a limit number calculating means 42 for obtaining a limit number that can be converted into a number from the average value and the standard deviation of the single quality quantities, and each of 1 to the limit number. It has the conversion information updating means 43 for obtaining the mass range for the number and setting it in the conversion means 27 as new conversion information.

The mass distribution calculation means 41 calculates the mass distribution such that the number of objects to be weighed is small (for example, one or two) so that an accurate conversion value can be obtained from the number conversion means 27. Use as a weighing hopper.

The weighing hopper, in which the number of objects to be weighed is small, may be one that naturally occurs during the weighing operation, or one that intentionally reduces the number of objects to be stored by reducing the supply amount.

In the former case, when the number conversion means 27 obtains a converted number of less than a predetermined number (for example, two), the average mass and standard deviation of a single product are obtained from the number and mass.

In the latter case, the supply amount of the object to be weighed to a specific small number of weighing hoppers is set to be always small, and the average single quality quantity is calculated from the number conversion result and the mass of the specific weighing hopper. And the standard deviation, or reduce the supply amount of the objects to be weighed to a specific weighing hopper or all the weighing hoppers at every predetermined time, and average from the number conversion results and mass of those weighing hoppers during that period. There is a method to obtain the mass and standard deviation.

As the simplest example below, the mass distribution calculating means 41 causes the target supply number of the objects to be weighed to the two specific weighing hoppers (for example, the weighing hoppers 23 ₁ and 23 ₂ ) to be ₁ periodically during the weighing operation. The feeder control means 33 is instructed so that the number of individual pieces is set to at least one, and the combination selection means 30 is instructed that at least one of the specific weighing hoppers is preferentially (or forcibly) selected for the combination, and the small amount supply period The mass calculating means 26 for a specific weighing hopper
Each time the number conversion means 27 obtains one conversion result for the mass calculated in step 1, the mass is stored as a single quality amount of the object to be weighed, and when a predetermined number of single quality amounts are stored, The average mass and standard deviation shall be calculated.

During this small amount supply period, the number conversion means
The mass of R pieces converted into one piece by 27 is u (1) to u
Assuming that (R), the average mass A ′ of a single product is A '= (1 / R) {u (1) + u (R)} And the standard deviation σ ′ is σ ′ = {(1 / R) Σ_{i = 1 to R}[U (i)-
A ']^Two}^1/2 Becomes

The limit number calculating means 42 receives the single product average mass A'calculated by the mass distribution calculating means 40 and the standard deviation σ ', and A'> 3σ '{m ^1/2 + (m + 1) ^1/2 }. The maximum number L among the numbers m for which is satisfied is determined as the limit number capable of number conversion.

Further, the conversion information updating means 43 has the number m =
Mass range for 1 to L, H (1) '= A' ± 3σ ' H (2) '= 2A' ± 3σ'2^1/2 H (3) '= 3A' ± 3σ'3^1/2 ...... H (L) ′ = LA ′ ± 3σ′L^1/2 Is calculated as conversion information, and this conversion information
The conversion information set in 27 is updated.

The combination weighing device 2 configured as described above
In 0, when the weighing operation for a new type of object is started, the target amount setting means 36 sets the target mass and the target number in the combination selecting means 30 in advance, and the conversion information setting means 37 causes the number converting means 27 to set. Conversion information H (1)
~ H (L) is initialized, and the supply amount of the feeders 21 _{1 to} 21 _P is set according to the set target amount, the number of hoppers to be combined, and the like, and then the operation is started.

When this operation is started, each feeder 21
₁ to 21 objects to be weighed from _P is supplied to the supply hopper ₂₂ 1 through 22 _P, the objects to be weighed are supplied from the respective feed hopper ₂₂ 1 through 22 _P into the weighing hoppers ₂₃ 1 ~ 23 _P, the were the supplied The mass of the object to be weighed is calculated by the mass calculating means 26, the number is calculated from the mass by the number converting means 27, and the combination selecting means 30 selects a combination within the target mass range within the target mass range. The weighing hopper containing the object to be weighed selected in 1 is opened and closed by the weighing hopper control means 31, and the objects to be weighed stored in the weighing hopper are discharged to the collecting and discharging device 25.

On the other hand, to the emptied weighing hopper, a new object to be weighed is supplied from the supply hopper corresponding to the weighing hopper by the feeding hopper control means 32, and the feeder control means is supplied to the emptied feeding hopper. By 33, a new object to be weighed is supplied from the feeder corresponding to the supply hopper.

The above-mentioned operations of weighing by the weighing hopper, selection of combination, and discharge of selected products and the operation of supplying the objects to be weighed to the empty weighing hopper are performed in parallel.
From the collective discharge device 25, the objects to be weighed within the target mass range and the target number range are collected and sequentially discharged.

FIG. 3 shows a processing procedure of the conversion information updating unit 40 during such a metering operation.
The operation of the conversion information updating unit 40 will be described below with reference to the flowchart of FIG.

During operation, every time a predetermined time elapses, a specific weighing hopper 23 ₁ , 2 is fed to the feeder control means 33.
It is instructed to set the supply target number of the objects to be weighed by the feeders 21 ₁ and 21 ₂ corresponding to 3 ₂ to ₁ , and the combination selection means 30 receives the specific weighing hoppers 23 ₁ and 23 2.
It is instructed that the objects to be weighed supplied to ₂ are included in the combination preferentially (or compulsorily) (S1 to S3).

As a method of preferentially including the objects to be weighed supplied to the specific weighing hopper in the combination, the mass of the objects to be weighed supplied to the specific weighing hopper is subtracted from the target mass range. Using the tentative target mass range obtained as a result and the tentative target number range obtained by subtracting the mass conversion result of the mass of the object to be weighed from the target number range, the objects to be weighed in the weighing hopper other than the specific weighing hopper are used. If the combination is selected, the selected weighing object and the weighing object in the specific weighing hopper are discharged together. If the combination cannot be selected, the specific weighing hopper is selected. Select a combination that falls within the original target mass range and target number range excluding the objects to be weighed.

When the objects to be weighed supplied to the specific weighing hopper are forced to participate in the combination, even if the combination cannot be obtained in the tentative target mass range and the tentative target number range, the tentative target mass range and the tentative target mass range cannot be obtained. A combination is selected that exceeds the upper limits of the target mass range and the target number range and becomes the minimum, and the selected objects to be weighed and the objects to be weighed in the specific weighing hopper are discharged together.

According to the above instruction, the specific weighing hopper 2
The number of objects to be weighed supplied to 3 ₁ , 23 ₂ is, for example, 1 ±
The number of conversions is about one, and the conversion result of "one" is output from the number conversion means 27 with high frequency.

Whenever the conversion result of "1" is output from the number conversion means 27, the mass before conversion is stored as a single quality quantity, and when the number of stored single quality quantities reaches a predetermined number R, the feeder is fed. The control means 33 is instructed to return the target supply quantity to the specific weighing hoppers 23 ₁ and 23 ₂ to the original state, and the combination selecting means 30 receives the objects to be weighed from the specific weighing hoppers 23 ₁ and 23 _2. An instruction is given to cancel the preferential combination participation (S4 to S8).

Then, the average mass A'of individual products and the standard deviation σ'for all the stored single quality quantities are calculated (S).
9, S10).

Further, a limit number L is obtained from the average mass A'of the single product and the standard deviation σ ', and the mass range H (1)' to H (L) 'is calculated for each number from 1 to L. Then, the conversion information of the number conversion means 27 is updated with the calculated conversion information (S11, S12).

In this way, the conversion information of the number conversion means 27 is regularly updated, so that, for example, as shown in FIG. 4, the lot of the object to be weighed is switched during the weighing operation, and the average mass of the individual item is initially set. When the value A changes to A ′ and the standard deviation changes from the initial value σ to σ ′, the mass range corresponding to each number also follows the change and the original set values H (1) to H (L) From H '(1) to H' (L), it is possible to always perform accurate number conversion.

Therefore, when the lots of the objects to be weighed are switched as in the conventional case, the operation is stopped, the single quality quantity of a large number of the objects to be weighed in the new lot is weighed, and the conversion information is calculated from the weighing result. Therefore, it is possible to cope with the fluctuation of the single quality quantity and the fluctuation of the standard deviation due to the lot switching while continuing the weighing operation, and the weighing efficiency is remarkably improved.

The conversion information updating unit 40 of the embodiment calculates the limit number L that can be converted into the number and calculates the mass range for each number from 1 to L as the conversion information. When the number of objects to be weighed supplied to each weighing hopper during operation is sufficiently smaller than the limit number L, the limit number calculation means 42 is omitted and the mass range up to the number that may be actually supplied is reached. May be calculated as the conversion information.

In the above example, as the simplest example, the target supply number of the objects to be weighed to the specific weighing hopper is one, and the mass when the conversion result of the one is obtained is the single quality quantity, Although the case where the average mass and the standard deviation are obtained has been described, it is also possible to make the supply target number of the objects to be weighed plural such as two or three.

For example, when the supply target number is two, as shown in FIG. 5, the target supply number of the objects to be weighed to the specific weighing hopper is instructed to be two,
It is instructed to give priority to the combination participation of the specific weighing hopper, and the mass when the conversion result becomes 2 is stored as a 2-piece set quality quantity, and the number of stored 2-piece set quality quantity is set to a predetermined number R. At this stage, the instruction to preferentially participate in the supply target number and combination for the specific weighing hopper is canceled, and the average mass B and standard deviation σ _{B of the} two-piece quality quantity are obtained (S21).
~ S30).

Then, the average mass B ″ and the standard deviation σ ″ of the single product are calculated from the average mass B and the standard deviation σ _{B of the} two-piece product (S31, S32).

That is, the average mass of each item to be weighed is A ″,
If the quasi-deviation is σ ″, the mass range for the two cases is
As did 2A "± 3σ" 2^1/2 Becomes

This mass range and the calculated flatness of the two-piece product
Homogeneous amount B and standard deviation σ_BMass range determined by B ± 3σ_B Is equal to.

Then, the average mass B of the two pieces and the single quality
Since it is equal to 2A ″, which is twice the average value A ″ of quantity, σ_B= Σ ″ 2^1/2 It can be expressed as.

Therefore, A ″ = B / 2 σ ″ = σ_B/ 2^1/2 By the calculation of
σ ″ can be obtained.

Although not shown, the supply target number is 3
When set to, the average mass C and standard deviation σ of the three-piece product_C
Seeking A ″ = C / 3 σ ″ = σ_C/ 3^1/2 The average mass A ″ and standard deviation σ ″ of a single item are calculated by
You can ask.

Then, from the thus obtained average mass A ″ and standard deviation σ ″, the limit number L is determined in the same manner as above, and the mass range for each number from 1 to L is determined,
The conversion information of the number conversion means 27 is updated (S33, S3).
4).

Further, in the above description, only one specific number of conversion results is calculated, but this does not limit the present invention. For example, as shown in FIG. The "hopper" and the "2" hoppers are the target weighing hoppers, and when the target weighing hoppers occur, their masses (single quality quantity or two-piece quality quantity) are stored, and the total number of these masses stored is a predetermined value R. At this stage, the average mass A ′, A ″ of the individual product and the standard deviations σ ′, σ ″ of the individual product are obtained (S
41-S47).

Then, the average of the individual product average masses A ′ and A ″ is obtained, and this is used as the final individual product average mass Ae, and the average of the standard deviations σ ′ and σ ″ is obtained. .sigma.e, and based on the final average mass Ae of the single product and the standard deviation .sigma.e of the single product, the limit number L is obtained in the same manner as above
The mass range of each number from 1 to L is calculated and the conversion information is updated (S48 to S51).

Further, in the above description, the average value and standard deviation of the single quality quantities are obtained from the average value and standard deviation of the masses of the objects other than one piece, and the conversion information based on the average value and standard deviation is used to calculate the present stage. However, the standard deviation of a single item calculated from the standard deviation of the objects to be weighed in multiple units is a predicted value, and the accuracy is lower than the standard deviation obtained by measuring the single item itself. Therefore, the standard deviation of the calculated single quality amount may be multiplied by a predetermined safety factor for use.

Further, in the above description, the conversion information of the number conversion means 27 is automatically updated periodically while the metering operation is continued, but the conversion information may be automatically updated by an instruction from the operation unit. You may comprise.

Further, as shown in FIG. 6, the conversion information may be automatically updated every time the number of single quality quantities required for updating the conversion information is obtained.

Further, as shown in FIG. 7, the conversion information updating unit 40 includes a mean value and a standard deviation, which are the basis of the conversion information currently used by the number conversion means 27, and a mass distribution calculation means 41. Distribution comparing means 45 for comparing the calculated average value and standard deviation is provided, and according to the comparison result,
The conversion information updating means 43 may update the conversion information.

As a processing method when the distribution comparing means 45 is provided, for example, as shown in the processing S61 to S63 of FIG. 8, the mass for each mass when the "1" conversion result is obtained. If the difference between the average value A ′ and the standard deviation σ ′ calculated by the distribution calculating means 41 and the average value Ar and the standard deviation σr that are the basis of the current conversion information are both reference values R and Q or less, the conversion information When the difference between at least one of the average value and the standard deviation exceeds the reference value without updating, the new conversion information based on the average value A ′ and the standard deviation σ ′ calculated by the mass distribution calculating means 41 is used. There is a way to update the conversion information. When the difference between at least one of the average value and the standard deviation exceeds the reference value, the distribution comparing means 45 stores the average value A ′ and the standard deviation σ ′ calculated at that time, and It is used as the average value Ar and the standard deviation σr that are the basis of the current conversion information in the distribution comparison.

As another processing method, the mass and the number of objects to be weighed stored in all or in a specific weighing hopper are usually supplied or a predetermined time elapses without performing the small amount supply described above. The average value and standard deviation of the single quality amount are calculated from the conversion result by the above-described calculation, and the calculated average value Ae and standard deviation σe (predicted value) of the single quality amount and the average value Ar that is the basis of the conversion information at the current stage. And the standard deviation σr are processed by the distribution comparison means 45 in steps S61 to S of FIG.
63, respectively.

When the difference between at least one of them exceeds the reference values P and Q, the target supply number of the objects to be weighed to the specific weighing hopper is "1" as in the processing of S2 to S12 in FIG. "Individual", it instructs that the objects to be weighed supplied to the specific weighing hopper are preferentially selected for the combination, and the conversion result for the mass of the objects to be weighed supplied to the specific weighing hopper is "1. The mass when it becomes "piece" is stored as a single quality amount, the accurate average value and standard deviation of this single quality amount are obtained, and the conversion information at the current stage is updated with the conversion information based on the average value and standard deviation. There is a way.

Further, in the above description, when a small amount of the object to be weighed is supplied to the specific weighing hopper, the objects to be weighed supplied to the specific weighing hopper are preferentially participated in the combination, and the single quality quantity is supplied in a short period. However, on the contrary, the objects to be weighed stored in a specific weighing hopper are regulated so that they will not be selected as a combination when this small amount is supplied, and the objects to be weighed for this specific weighing hopper are controlled. Add a small amount of additional charge, calculate the mass of the added additional object from the difference between the mass before the addition and the mass after the addition, and sequentially store the number obtained by converting the mass to the specified number, When the stored value for the number of pieces is obtained, the average value and the standard deviation of the single quality amount are obtained in the same manner as above, and the current conversion information is obtained by the new conversion information obtained from the obtained average value and the standard deviation of the single quality amount. Update or Performs distribution comparison by distribution comparison means 45 that describes may update the conversion information according to the comparison result.

In the above description, the combination selecting means 30
Although the combination which is within the target mass range and within the target number range is selected in, the present invention can be applied to the case where the objects to be weighed are combined only by the number regardless of the mass.

[0079]

As described above, the combination weighing device of the present invention receives the mass from the mass calculating means and the number from the number converting means during the weighing operation, and the currently supplied objects to be weighed. Mass distribution, that is, the average value and standard deviation of the single quality amount is obtained, new conversion information is calculated from the average value and standard deviation, and the conversion information set in the number conversion means by the calculated conversion information Have been updated.

For this reason, even if the unit quality quantity and its variation fluctuate due to switching of the lot of the object to be weighed during the weighing operation, the conversion information is updated following the variation.
Accurate number conversion can always be performed, operation stop is not required as in the past, and the weighing efficiency is remarkably increased.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a mechanism unit according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a control unit according to the embodiment of the present invention.

FIG. 3 is a flowchart showing an example of a processing procedure of a main part of the embodiment.

FIG. 4 is a diagram for explaining the operation of the embodiment.

FIG. 5 is a flowchart showing another example of the processing procedure of the main part of the embodiment.

FIG. 6 is a flowchart showing another example of the processing procedure of the main part of the embodiment.

FIG. 7 is a diagram showing a modified example of the main part of the embodiment.

FIG. 8 is a flowchart showing a processing procedure of main parts of the embodiment.

FIG. 9 is a diagram showing the mass distribution of the object to be weighed.

FIG. 10 is a diagram showing a mass distribution of an object to be weighed.

[Explanation of symbols]

20 ... Combination weighing device, 21 _{1 to} 21 _P ... Feeder, 22 _{1 to} 22 _P ... Supply hopper, 23 ₁ to 23 _P ...
... weighing hopper, 24 _{1 to} 24 _P ... weighing device, 25 ... collecting discharge device, 26 ... mass calculating means, 27 ... number conversion means, 30 ... combination selecting means, 31 ... weighing hopper control means, 32 ... Supply hopper control means, 33 ... Feeder control means, 35 ... Parameter setting section, 36 ... Target amount setting means, 37 ... Conversion information setting means, 38 ... Display device, 39 ... Operation section, 40 ... Conversion information update section, 41
...... Mass distribution calculation means, 42 ・ ・ ・ Limit number calculation means, 4
3 ... Conversion information updating means, 45 ... Distribution comparison means

Claims (3)

[Claims] 1. The mass of each object to be weighed supplied to a plurality of weighing units and detected is converted into a number based on preset conversion information, and the object to be weighed is converted based on the converted number. In a combination weighing device that selects a combination and discharges the objects to be weighed selected in the combination from the weighing unit, the weight of the objects to be weighed detected by the plurality of weighing units during operation and the number conversion result thereof are used. Based on this, a mass distribution calculating means (4) for calculating the average value and standard deviation of the single quality quantities of the objects to be weighed.
1) and conversion information updating means (43) for updating conversion information necessary for number conversion based on the average value and standard deviation calculated by the mass distribution calculating means. Weighing device. 2. A distribution comparing means (45) for comparing the average value and standard deviation calculated by the mass distribution calculating means with the average value and standard deviation on which the current conversion information is based, 2. The combination weighing device according to claim 1, wherein the information updating means updates the conversion information according to the comparison result of the distribution comparing means. 3. A supply means (21, 22) for automatically supplying an object to be weighed to the plurality of weighing units, wherein the mass distribution calculation means is provided with at least an average value and a standard deviation by the distribution comparison means. When it is determined that one of the differences is equal to or greater than the reference value, the supply unit is instructed to supply one object to be measured to at least one specific measuring unit of the plurality of measuring units. Then, it is configured to calculate the average value and standard deviation of the single quality amount from the weighing result of the specific weighing unit, the conversion information updating means, the average value calculated by the mass distribution calculating means for the specific weighing unit. The combination weighing device according to claim 2, wherein the current conversion information is updated with conversion information determined by the standard deviation.