JPH0695037B2 - Combination weighing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Field of Use of the Present Invention> The present invention is designed to make articles such as confectionery, fruits, and vegetables whose individual weights vary so as to have a substantially constant weight.
The present invention relates to a combination weighing device used when packing a plurality of pieces into a bag and the like.

<Prior Art> (FIGS. 3 and 4) Even if an attempt is made to collect a plurality of objects to be weighed, each of which has a variation in individual weight, by a set weight, an error occurs between the weight and the set weight. This error becomes more significant as the average weight of one object to be weighed increases.

In order to solve this problem, the combination weighing device shown in FIG. 3 is generally used.

That is, in the combination weighing apparatus, a plurality of weighing hoppers 2 ₁ -
To 2 _n, one substantially M frequency setting weight (M is the combination number of the weighing hoppers serving as the target) of the objects to be weighed corresponding to the supply by the feeder 1 ₁ to 1 _n, respectively, each weighing hopper 2 ₁ to 2 _n The contained objects to be weighed are respectively weighed by the weighing devices 3 _{1 to} 3 _n provided for each. Then, based on the outputs of the weighing devices 3 _{1 to} 3 _n , the combined weight of the objects to be weighed is calculated for all the different combinations. Among the combined weights, a combination having the smallest difference from the set weight W is selected, and the objects to be weighed in the weighing hopper are discharged and collected on the collecting chute 4 or the like.

Therefore, in the conventional combination weighing device having such a configuration, the weight of the objects to be weighed stored in each weighing hopper is a value W / M obtained by dividing the set weight W by the number M of combinations, that is, the weighing hopper 1 M varies with the target supply weight per piece.
The combined weight of the objects to be weighed in each weighing hopper also varies greatly, and W / (M-1) or W / (M
Any combination of +1) occurs frequently. That is, the fourth
As indicated by the symbol a in the figure, if the variation width of the measured values of a plurality of objects to be weighed in one weighing hopper is wide around W / M, the combined weight of M weighing hoppers will be The width of the variation also becomes wider as shown by the symbol b in FIG. 4, and the number of combinations that can be used for creating the optimum value decreases. Therefore, in order to always obtain the combined weight as a value very close to the set weight W, the supply amount of the objects to be weighed by each feeder to each weighing hopper must always be a value very close to W / M. I have to.

However, even if the control parameter is constant, the supply amount of the feeder changes greatly with the fluctuation of the power supply voltage and the change of temperature and humidity. Fluctuations in the supply amount due to such environmental changes show a common tendency for all feeders, and as a technique for preventing this common fluctuation, there have been hitherto disclosed JP-A-57-169627 and JP-A-59-623.
No. is known.

In Japanese Patent Laid-Open No. 169627/1982, the value obtained by adding the weight values of all the weighing tanks not selected for the combination is divided by the number of the weighing tanks to obtain the average weight per weighing tank. A technique for controlling the next supply amount according to the result of comparison between the average weight and the target weight is disclosed.

Further, in JP-A-59-623, the total weight of the objects to be weighed in the accommodated hopper is subtracted from the total target weight obtained by multiplying the target weight per hopper by the total number of weighing hoppers, and the subtraction result is empty. A technique for controlling the next feeding force of the feeder to the empty weighing hopper is disclosed by the ratio of the result of division by the number of hoppers to the target weight per hopper.

<Problems to be Solved by the Present Invention> However, in JP-A-57-169627, correct control cannot be performed unless the objects to be weighed are supplied to all the weighing tanks that are not selected for combination. That is, in this type of weighing device, it often happens that the object to be weighed is caught on the feeder and the supply is temporarily stopped (bridge state). However, in this technique, an empty space generated by such a bridge is generated. Since the measuring tank is also calculated as a residual tank,
There was a problem that the next supply would drop significantly.

Further, as in Japanese Patent Laid-Open No. 59-623, the value obtained by subtracting the total weight of the objects to be weighed in the accommodated hopper from the total target weight obtained by multiplying the target weight per hopper by the total number of weighing hoppers is used as the number of empty hoppers. In the method of controlling the feeding force of the next feeder by the result of dividing by, the driving force of the next feeder is determined irrespective of the driving force of the previous feeder, so the feeding force of the feeder itself with respect to the driving force changes suddenly. The reactivity of the case is extremely low,
There was a problem that the average capacity of the weighing hopper did not reach the target weight immediately. Further, while the total weight of the objects to be discharged in one combination is almost the set weight, the number of the discharge hoppers may be 3 or 6, The driving force will change drastically depending on the number of hoppers. That is, there is a problem that the next driving force is twice as different between the case where the number of empty hoppers is 3 and the case where the number of empty hoppers is 6, and a feeder having an extremely wide variable range of the feeding force must be used.

Further, in general, the relationship between the feeding force parameter of the feeder and the supply amount is often not proportional. Therefore, if the feeding force is varied in a wide range, the control becomes excessively or insufficiently, and the supply amount becomes unstable. There was also a problem.

It is an object of the present invention to provide a combination weighing device that solves the above problems.

<Embodiment of the present invention> (Figs. 1 and 2) Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

1 and 2 show an embodiment of the present invention. FIG. 1 is a schematic configuration diagram of a mechanical unit of a combination weighing device, and FIG. 2 is a schematic configuration diagram of a control unit.

In FIG. 1, 11 is a feeder for sequentially feeding the objects to be weighed to a circular feeder 12. N intermediate hoppers 14 _{1 to} 14 _n are circularly arranged below the peripheral edge of the circular feeder 12, and the objects to be weighed are supplied via the feeders 13 _{1 to} 13 _n , respectively.
Below the intermediate hoppers 14 _{1 to} 14 _n are weighed hoppers 16 respectively.
_{1 to} 16 _n are installed. The objects to be weighed stored in the intermediate hoppers 14 _{1 to} 14 _n are dropped and stored in the weighing hoppers 16 _{1 to} 16 _n when the discharge gates 15 ₁ to 15 _n are opened.

The weighing hoppers 16 _{1 to} 16 _n are provided with weighing devices 17 _{1 to} 17 _n , respectively. Each of the weighing devices 17 _{1 to} 17 _n is a weighing hopper.
The objects to be weighed stored in 16 _{1 to} 16 _n are weighed and the measured value is output.

A collecting chute 19 is installed below the weighing hoppers 16 _{1 to} 16 _n . The objects to be weighed which have been accommodated in the weighing hoppers 16 ₁ ~ 16 _n are discharge gate 18 ₁ ~ 18 _n respectively weighing hoppers 16 ₁ ~ 16 _n
When you open, it falls on the gathering chute 19.

A packaging machine 21 is installed below the collecting chute 19. The bottom of the collecting chute 19 is provided with a timing hopper 20 that opens at regular time intervals or in synchronization with the packaging machine 21.

The discharge gates 18 ₁ to 18 _n are opened / closed by the discharge control device 33 of the combined discharge device 30.

As shown in FIG. 2, the combination discharge device 30 includes a measured value storage circuit 31, a combination selection circuit 32, and a discharge control device 33.

The respective measured values from the measuring devices 17 _{1 to} 17 _n are combined discharge devices.
It is sent to the weighing value storage circuit 31 of 30. The weighing value storage circuit 31 stores therein the weighing values of the contents in the weighing hoppers 16 _{1 to} 16 _n .

The combination selection circuit 32 calculates a combination weight of the objects to be weighed for all different combinations based on the measured values of the contents of the weighing hoppers 16 _{1 to} 16 _n stored in the measured value storage circuit 31. The unit 32a, the weight setting unit 32b for setting and storing the set weight W, and the combination weight output of the combination calculating unit 32a and the set weight output of the weight setting unit 32b are compared, and the difference between the set weight and the set weight becomes the smallest. And a combination discriminating unit 32c for selecting a combination of weighing hoppers and outputting a combination selection signal.

Upon receiving the combination selection signal, the discharge control device 33 opens the gate of the weighing hopper selected for the combination of the discharging gates 18 ₁ to 18 _n of the weighing hopper, and at the same time, discharges the weighing hopper that has been discharged after a certain period of time. The opening / closing control of the opening / closing gate is performed so as to open the discharge gate of the intermediate hopper corresponding to.

Further, the respective measured values from the respective measuring devices 17 _{1 to} 17 _n are sent to a supply amount control circuit 40 for controlling the supply amount of the feeder to the empty weighing hopper, as shown in FIG.

The supply amount control circuit 40 includes a total weight calculation circuit 41, a stored hopper number detection circuit 42, and a divider as an average storage amount calculation means.
46, target weight calculation circuit 47, parameter calculation circuit 50
And a feeder control device 60.

The measured values from the respective weighing devices 17 _{1 to} 17 _n are input to the total weight calculation circuit 41, and the measured values of all the weighing hoppers 16 _{1 to} 16 _n are added.

Further, the measured values from the respective scales 17 _{1 to} 17 _n are input to the comparators 43 ₁ to 43 _n of the accommodated hopper number detection circuit 42, respectively.
The comparators 43 ₁ to 43 _n respectively compare the value indicating weight zero set in the zero setter 44 and the measured value, and when the measured value is greater than zero, “1” is set, and when zero, Is "0", bit adder
Output to 45. The bit adder 45 adds the outputs of the comparators 43 ₁ to 43 _n . Therefore, the output L of the bit adder 45 represents the number of non-empty stored weigh hoppers. The divider 46 divides the added value W _a from the total weight calculation circuit 41 by the output L of the bit adder 45. Therefore, the output W _a / L of the divider 46 represents the average storage amount of the objects to be weighed supplied to the weighing hopper.

The divider 48 of the target weight calculation circuit 47 divides the set weight W set in the weight setting unit 32b by the target combination number M set in the combination hopper number setter 49. Therefore, the divider 48
Output W / M is set weight W by combining M weighing hoppers.
Represents the target supply weight for each weighing hopper in the case of obtaining.

The divider 51 of the parameter calculation circuit 50 divides the average accommodation amount from the divider 46 by the supply target weight from the divider 48. Therefore, the output of the divider 51 represents the ratio of the target supply weight per weighing hopper to the average storage capacity per non-empty weighing hopper at this stage.

The parameter storage unit 52 as the parameter storage unit of this embodiment stores and outputs the force-feeding parameter F _N that determines the vibration amplitude and vibration time of the feeder. The multiplier 53 multiplies the output of the divider 51 by the power transmission parameter F _N stored in the parameter storage 52. Therefore, the output of the multiplier 53 represents a new transmission force parameter F _{N + 1} for the next average storage amount to approach the supply target weight (W / M).

The switch 54 is the power transmission updating means of this embodiment, and stores the new power transmission parameter F _{N + 1} from the multiplier 53 in the parameter memory 52 instead of the previous power transmission parameter F _N.

The feeder control device 60 is the feeder control means of this embodiment, and in order to selectively drive each feeder with a drive signal proportional to the power transmission parameter stored in the parameter storage unit 52, a supply control circuit 61, It is composed of multipliers 62 _{1 to} 62 _n and drive circuits 63 _{1 to} 63 _n provided corresponding to the respective weighing hoppers.

The supply control circuit 61 receives, for example, a signal from the discharge control device 33, and outputs a supply signal of, for example, numerical value 1 to the multiplier corresponding to the weighing hopper that needs to supply the object to be weighed via the intermediate hopper. , Outputs a signal of numerical value 0 to the multiplier corresponding to the weighing hopper which does not need to supply the objects to be weighed. Multiplier 62
_{1 to} 62 _n are the supply signals output from the supply control circuit 61,
The power transmission parameter stored in the parameter storage 52 is multiplied.

The drive circuits 63 _{1 to} 63 _n use the drive signals corresponding to the outputs from the multipliers 62 _{1 to} 62 _n to supply the feeders 13 ₁ to ₁ 1 corresponding to the empty weighing hoppers.
Vibration drive 3 _n .

<Operation of Embodiment> Next, the operation of the combination weighing device according to the above embodiment will be specifically described.

The object to be weighed is fed through the feeder 11 and circular feeder 12
13 ₁ to 13 _n are supplied to the intermediate hopper 14 _{1-14 n,} respectively, by an intermediate hopper 14 _1-14 through _n respective weighing hoppers 16 ₁ ~ 16 _n
Are stored in and weighed.

Then, among the N total weighing hoppers 16 _{1 to} 16 _n , the L weighing hoppers have already accommodated the objects to be weighed by the respective feeders, and the remaining (N−L) weighing hoppers have been discharged. , The weighing hoppers 16 _{1 to} 16 _n
Weighing values from each measuring instrument 17 ₁ to 17 _n corresponding to the comparators 43 ₁
.. 43 _n , it is detected whether it is empty or not, and the bit adder 45 outputs a signal representing L to the divider 46.

On the other hand, each measured value is added by the total weight calculation circuit 41 to obtain the total weight.
Wa is output to the divider 46, and as a result, from the divider 46,
The average storage amount Wa / L of the objects to be weighed supplied to the non-empty stored weighing hopper is output.

The target weight calculation circuit 47 outputs the target supply weight W / M per weighing hopper.

The parameter calculation circuit 50 divides the supply target weight per one weighing hopper by the average capacity of the L non-empty weighing hoppers, and multiplies the present feed force parameter F _N.

As a result, this multiplication output F _{N + 1} becomes F _{N + 1} = [(W / M) ÷ (Wa / L)] F _N. Then, this multiplication output F _{n + 1} is updated and stored in the parameter storage unit 52 via the switch 54 as a new power transmission parameter.

Transmission force parameter newly stored in the parameter storage unit 52
F _{N + 1} is sent to the feeder control device 60, the drive circuits 63 _{1 to} 63 _n corresponding to the empty weighing hopper drive the feeder by the drive signal proportional to the new feed force parameter F _{N + 1} ,
The objects to be weighed supplied from the feeder are supplied to the empty weighing hopper via the intermediate hopper.

The new feed force parameter F _{N + 1} is the target supply weight (W +
Since M) is a constant, it is determined by the ratio between the average capacity of the objects to be weighed by the feeder driven previous Okuchikara parameter F _N and its Okuchikara parameter F _N (Wa / L). Therefore, even if the supply amount of the feeder is greatly reduced due to the reduction of the vibration force of the feeder itself,
The supply amount is increased by the amount that the supply amount is expected to decrease with respect to the previous feeding force parameter, and the average storage amount by the next supply of the objects to be weighed quickly approaches the supply target weight.

Further, even if an empty weighing hopper is generated due to a bridge or the like, the new parameter value is determined by the average storage amount of the stored hoppers, so that the calculation error due to the empty hopper does not occur.

Further, under the condition that the total weight value of the objects to be weighed in the accommodated hopper is the same, for example, when the total number of hoppers is 16,
When the number of empty hoppers is 3 and when the number of empty hoppers is 6, the next parameter is (16-3) / (16-6) = 13/10. It's narrow.

In this way, when the supply to all the weighing hoppers 16 _{1 to} 16 _n is completed, the combination selection circuit 32, based on each weighing value stored in the weighing value storage circuit 31 for all the weighing hoppers 16 _{1 to} 16 _n. , The combination weight is calculated for all the different combinations, the weighing hopper combination having the smallest difference from the set weight W set in the weight setting unit 32b is selected, and a combination selection signal is sent to the discharge control device 33. To do. The discharge control device 33 opens the discharge gate of the weighing hopper designated by the combination selection signal, and discharges to the collecting chute 19. The discharged objects to be weighed are gathered together by a collecting chute 19, and when the timing hopper 20 opens, they fall into the packaging machine 21 and are packed in bags.

When one combined discharge is completed in this way, next,
For the empty empty weighing hopper, the same as the supply control circuit.
The objects to be weighed are accommodated from the respective feeders whose feeding force is controlled by 40, and the combination weighing is sequentially repeated by the same operation.

In the above embodiment, the feeder feeding force was controlled every time weighing was performed, but this may be performed every several weighings by changing the operation timing of the switch 54, Alternatively, it may be at regular intervals.

<Effects of the Present Invention> As described above, in the combination weighing device of the present invention, the feeding force parameter at the present stage is divided into the value obtained by dividing the supply target weight per weighing hopper by the average storage amount of the stored weighing hoppers. A new feeding force parameter is calculated by multiplying by, and the feeder corresponding to the empty weighing hopper is driven by the drive signal proportional to this new feeding force parameter to supply the object to be weighed.

Therefore, even if the vibration force of the feeder itself suddenly changes and the actual sending force for the drive signal suddenly changes, the feeder driving is performed next time by the sending force parameter that allows for this change.
The average storage amount can be quickly brought close to the supply target weight. Further, it is possible to stably supply the objects to be weighed to the weighing hopper with a feeder having a small variable range regardless of the presence or absence of an empty hopper due to a bridge or the like.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a mechanical portion of one embodiment of the present invention,
FIG. 2 is a schematic configuration diagram showing the control unit. FIG. 3 is a schematic configuration diagram showing a conventional combination weighing device, and FIG. 4 is a diagram showing the relationship between the weight distribution of the contents of the weighing hopper and the distribution of the combined weight. 11 …… Supplier, 12 …… Circular feeder, 13 _{1 to} 13 _n …… Feeder, 16 _{1 to} 16 _n …… Weighing hopper, 17 _{1 to} 17 _n …… Weighing machine,
18 ₁ ~18 _n ...... discharge gate, 19 ...... collecting chute, 30 ......
Combination discharging device, 31 ... Weighing value storage circuit, 32 ... Combination selecting circuit, 33 ... Discharge control device, 40 ... Supply amount control circuit, 41 ... Total weight calculation circuit, 42 ... Detection of number of stored hoppers Circuit, 46 ... Divider, 47 ... Target weight calculation circuit, 50 ...
Parameter calculation circuit, 60 ... Feeder control device.

Claims (1)

[Claims] 1. A plurality of feeders (13 _{1 to} 13 _n ) for feeding an object to be weighed with a feeding force according to a drive signal, and a parameter storage for storing a feeding force parameter for determining the feeding force of the plurality of feeders. Means (52), feeder control means (60) for selectively driving each of the feeders with a drive signal proportional to the power transmission parameter stored in the parameter storage means, respectively corresponding to the plurality of feeders. provided, wherein a plurality of weighing hoppers for receiving the objects to be weighed (16 ₁ ~ 16 _n) fed from the feeder, a plurality of measuring instruments for measuring a plurality of supplied to the weighing hoppers the objects to be weighed, respectively (17 ₁ ˜17 _n ) and a combination of the objects to be weighed by the plurality of weighing devices, a combination close to the set weight (W) is selected based on each measured value, and the selected objects to be weighed are selected. Ejection group The discharge device (30) and a plurality of weighing hoppers receiving the weighing signals from the plurality of weighing devices, and detecting the number (L) of the stored hoppers in which the objects to be weighed are stored among the plurality of weighing hoppers. Hopper number detection circuit (4
2), a total weight calculation circuit (41) for calculating the total weight value (Wa) of the objects to be weighed in the accommodated hopper, and the total weight value divided by the number of accommodated hoppers to obtain the accommodated An average storage amount calculation means (46) for calculating an average storage amount (Wa / L) per hopper, and a target supply weight of the objects to be weighed per weighing hopper are calculated by the average storage amount calculation means. A division means (51) for dividing by the average storage capacity; a multiplication means (53) for multiplying the division result of the division means by the current-stage power transmission parameter stored in the parameter storage means; A power feeding updating means (54) for storing the multiplication result as a new power feeding parameter for the next feeder driving in the parameter storage means is provided, and the feeding power proportional to the power feeding parameter updated and stored in the parameter storage means. Power to empty weighing hopper The combination weighing device supplies objects to be weighed to drive the feeder to respond.