JP2000193513A - Weight checker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a weight checker whose high metering accuracy can be maintained almost without lowering its rate of operation. SOLUTION: In this weight checker 300, the weight of a product is measured while the product is being conveyed by a conveyor 310, and whether the product is good or not is judged. A comparison means 31f by which information regarding the metered value of the product measured by the weight checker is compared with information regarding metered values by other metering devices is installed. In addition, a discrimination means 31c by which, when a compared result by the comparison means 31f is deviated from a tolerance, a probability that a zero-point defect is generated in the weight checker is judged is installed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a weight checker.

[0002]

2. Description of the Related Art As shown in FIG. 7, there is conventionally known a weight checker 300 for weighing and inspecting goods while transporting the goods. Such a weight checker 300
Is a state in which there is no product M1 on the conveyor 310, that is,
Zero adjustment is performed in the empty state.

[0003]

However, in a system in which a high-speed packaging machine or the like is arranged upstream of the weight checker 300, the operation efficiency of the weight checker 300 increases,
When the operating rate becomes high in this way, as shown by the broken line and the solid line in FIG. 7, the interval between the products M1 approaches, so that an empty state cannot be obtained, so that the zero point adjustment cannot be performed. Therefore, the weighing accuracy of the weight checker 300 decreases. Therefore, an object of the present invention is to provide a weight checker that can maintain high weighing accuracy without substantially lowering the operation rate.

[0004]

In order to achieve the above object, the present invention is a weight checker for determining the acceptability of a product by measuring the weight of the product while transporting the product on a conveyor. Comparing means for comparing the information on the weighing value of the product measured by the checker with the information on the weighing value of the same product measured by another weighing device, and when the comparison result by the comparing means deviates from an allowable value. Determining means for determining that there is a possibility that a zero point defect has occurred in the weight checker.

In the present invention, if it is determined that there is a possibility that the zero point defect has occurred, for example, the delivery of the goods to the weight checker is delayed so that the weight checker is stopped while the goods are not carried in. Make zero adjustment.

[0006] In the present invention, "information on weighing value"
The term includes not only information on the weighing value of one product but also information on the weighing values of a plurality of products (for example, an average value obtained by averaging the weighing values of a plurality of products). The “other weighing device” refers to a weighing device that weighs a product or an article corresponding to the product weighed by the weight checker, and the “other weighing device” includes, for example, a combination weighing device. Further, the “comparison result” is not limited to the difference or ratio of the information regarding the two measurement values, but also includes the change of the difference or ratio. For example, when the difference or the ratio is larger than a predetermined allowable value, it can be determined that the measuring instrument has deteriorated.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. First, an outline of a weighing and packaging inspection system to which the present invention is applied will be described. In FIG. 1, 100 is a conveyor, 1 is a combination weighing device (other weighing device), 200 is a bag making and packaging machine, 300 is a weight checker, 400 is a seal checker, and 700 is a box packing device. The conveyer 100 has a content M which is an object to be weighed.
Is dropped to the center of the dispersion feeder 2 of the combination weighing device 1.

As shown in FIG. 2, a plurality of sets of supply troughs 3i composed of electromagnetic feeders are provided on the periphery of the dispersion feeder 2. The dispersion feeder 2 and the supply troughs 3i vibrate by driving the vibrating device, respectively, so that the contents M on the dispersion feeder 2 are supplied to the supply troughs 3i.
Is supplied to a number of pool hoppers 4i provided downstream of the pool hopper. Each of the pool hoppers 4i is provided with a gate 5i, and temporarily stores and stores the content M supplied and received from each of the supply troughs 3i. A measuring hopper 6i is provided downstream of each pool hopper 4i. Each of these weighing hoppers 6i has a weighing head and a gate 8i having a weight detector 7i for detecting the weight of the contents M put into the weighing hopper 6i from the pool hopper 4i.
Is provided. A large collecting and discharging chute 9 is provided below the gate 8i, and the contents M are collectively (combined and discharged) by combining the weights of the contents M detected by the respective weight detectors 7i. The content M is dropped to the bag making and packaging machine 200 of FIG. 1 at predetermined intervals at a target value or a value close to the target value.

A bag making and packaging machine 200 shown in FIG. 1 is a so-called vertical pillow wrapping machine. A sheet film F unwound from a film roll Fr is welded by a vertical sealer 201 to form a tube, and from the top, In a state where the falling contents M are filled in the cylindrical film F, the upper end F1 of the contents M in the film F is welded (sealed) by the end sealer 202 and cut to cut the product M1 continuously. (See, for example, JP-A-4-28105).
The packaged product M1 falls downward, and the
1 and is conveyed by falling on the receiving conveyor 302. The goods M1 are conveyed from the receiving conveyor 302 to the weight checker 300 at a predetermined pitch.

As shown in FIG. 3, the weight checker 300 has a weight detector 305 such as a load cell for measuring the weight of the product M1, and a conveyor 310 supported by the weight detector 305. The conveyor 310 has a drive belt 303. The weight checker 300 of FIG.
Measures the weight of the product M1 while conveying the product M obliquely upward by a method described later. The product M1 is conveyed from the weight checker 300 to the seal checker 400.

The seal checker 400 conveys the product M1 conveyed from the weight checker 300 obliquely upward while pressing the product M1 from above with the presser 401, and inspects the sealing failure of the packaging bag and the length of the product M1. The sorting device 500 discharges the product M1 received from the seal checker 400 out of the system if it is defective, and conveys the product M1 downstream if it is non-defective, based on the inspection results. The product M1 is transported to the downstream packaging device 700 via a transport device including the sorting device 500 and the alignment transport device 600. The packing device 700 packs the product M1 in the cardboard box B.

Next, the configuration of the main part of the present system will be described. As shown in FIG. 3, the combination controller 10 and the checker control unit 30 of the combination weighing device 1 and the weight checker 300 are connected to devices such as an actuator and a motor via an interface (not shown). The combination controller 10 and the checker control unit 30 are connected to each other via an interface (not shown).

The combination controller 10 calculates a combination calculation value Wc by combining one or more of the weighing values output from the weight detector 7i, compares the combination calculation value Wc with a predetermined combination target value, and Of the combinations whose calculated value Wc is equal to or close to the combination target value, the combination closest to the combination target value is determined, and FIG.
Is opened, and the contents M are combined and discharged from the weighing hopper 6i to the collecting discharge chute 9.

The checker control unit 30 includes a microcomputer 3
5, a weight detection circuit 306, a product detection circuit 307, and a motor control circuit 309. Weight detection circuit 306
The motor control circuit 309 is connected to the microcomputer 35 via an interface (not shown).
The weight detection circuit 306 is connected to the weight detector 305 and receives a weighing signal from the weight detector 305.

The product detection circuit 307 includes the product detector 30
8 is connected. The product detector 308 is, for example, a photodetector, and as shown in FIG.
10 and a receiving conveyor 302. When the product detector 308 detects the product M1, the product detection circuit 307 of FIG. 3 outputs a product detection signal to the weight detection circuit 306. The weight detection circuit 306 outputs to the microcomputer 35 a weight signal obtained by removing a vibration component from the weighing signal at a predetermined timing based on the product detection signal.

On the other hand, when the weighing signal from the weight detector 305 falls below a predetermined reference voltage, that is, when the conveyor 310 is empty, the weight detection circuit 306 outputs a zero point signal including the weighing signal to the microcomputer. 35. By subtracting the zero point signal and the tare weight from the weight signal, the post-weighing value Ws, which is the net weight of the product M1, is obtained. The motor control circuit 309 controls a drive motor (not shown) of the conveyor 310 and the like.

The microcomputer 35 includes a CPU 31 and a ROM.
32 and a RAM 33. In the RAM 33,
A pass reference value storage unit 33a, a weight history storage unit 33b, an average value storage unit 33c, an allowable value storage unit 33d, and a zero point weight storage unit 33e are provided. Acceptance criterion storage unit 33
In a, a pass criterion value serving as a criterion for the pass / fail of the product M1 is stored (generally, an acceptable range serving as a criterion for the pass / fail) is stored. The CPU 31 compares the post-weighing value Ws with the passing reference value, and determines that the product M1 is acceptable if the post-weighing value Ws is within the passing reference value. On the other hand, the CPU 31
If it is determined that the product M1 is unacceptable, it outputs a distribution signal to the distribution device 500 and discharges the defective product M1 out of the system.

As shown in FIG. 4, the weight history storage unit 3
In 3b, a combination calculation value Wc measured from one time to n times prior to the product M1 determined to be acceptable is stored. In addition, the weight history storage unit 33b stores in the product M1 (the content M discharged in combination) corresponding to each of the combination calculation values Wc.
The post-weighing value Ws of the product M1) in which the same product is packaged is stored. The combination calculation value Wc and the post-weighing value Ws are updated and stored each time the weighing is performed.

The CPU 31 calculates a combination average value Wa and a post-weighing average value Wb by averaging the combination calculation value Wc and the post-weighing value Ws for n times stored in the weight history storage unit 33b of FIG. The average value storage unit 33c stores the combination average value Wa and the post-weighing average value Wb. An allowable value Wp described later is stored in the allowable value storage unit 33d of FIG. The zero point weight of the present and previous times is updated and stored in the zero point weight storage unit 33e.

The CPU 31 comprises a weighing means 31a, a first
Comparison means 31b, determination means 31c, zero point adjustment means 31
d and second comparing means 31f. CPU31
The weighing means 31a calculates the post-weighing value Ws by subtracting the zero point signal from the weight signal output from the weight detection circuit 306, and further subtracting a predetermined tare weight from the weight.

The first comparing means 31b calculates the combination average Wa and the post-measurement average value Wb, and subtracts the post-measurement average value Wb from the obtained combination average Wa to calculate the measurement deviation (WaｂWb). I do. The determination unit 31c compares the weighing deviation (Wa─Wb) with the allowable value Wp, and determines whether there is a possibility that a zero point defect has occurred based on the comparison result. The zero-point adjusting means 31d performs a known zero-point adjustment (for example, actual fair 3-32985).
No., column 6, line 39 to column 7, line 6). The second comparing means 31f calculates a result of the zero point adjustment and the weighing deviation (Wa─).
Wb) is compared, and it is determined whether or not a zero point failure has occurred.

A touch screen 34 is connected to the checker control unit 30 via an interface (not shown). The touch screen 34 has, for example, a liquid crystal display, and performs various displays based on an output from the CPU 31.

When the combination controller 10 receives a pause signal, which will be described later, from the checker control unit 30, the combination weighing device 1 causes the combination weighing device 1 to suspend one combination discharge of the contents M.

Next, an example of the principle and operation of the present invention will be described. As shown in FIG. 4, the weight checker 300
The combination average value Wa is calculated for the combination calculation value Wc for n times of the most recently weighed contents M among the products M1 whose weights have been checked as appropriate. A post-measurement average value Wb is calculated for the post-measurement value Ws of the content M that is the same as the content M for which the combination calculation has been performed. Next, the post-measurement average value Wb is subtracted from the combination average value Wa to obtain a measurement deviation (Wa─Wb).
Is calculated. Here, the two average values Wa, Wb
Is an average value obtained by measuring the weight of the same content M, and therefore, should originally match. Therefore, the weighing deviation (Wa─Wb) is compared with a predetermined allowable value Wp. If the weighing deviation (Wa─Wb) exceeds the allowable value Wp, there is a possibility that the weight checker 300 has a zero point defect. It can be determined that there is.

FIG. 5 shows the zero point adjustment mode.
This will be described with reference to the flowchart of FIG. In step S1, the first comparing means 31b calculates the measurement deviation (WaＷWb) by subtracting the post-measurement average value Wb from the combination average value Wa, and further calculates the absolute value of the deviation. Determination means 31
c reads the allowable value Wp from the allowable value storage unit 33d,
The absolute value of the measurement deviation (WaＷWb) is compared with the allowable value Wp. When the absolute value of the weighing deviation (Wa─Wb) is larger than the allowable value Wp, the determination unit 31c determines that there is a possibility that the weight checker 300 has a zero point defect, and proceeds to step S2. On the other hand, the measurement deviation (Wa─W
If the absolute value of b) is not more than the allowable value Wp, step S1
Return to

In step S2, checker control unit 30
Performs zero adjustment. That is, when the CPU 31 outputs a pause signal to the combination controller 10 or the bag making and packaging machine 200, the combination weighing device 1 of FIG. 1 suspends the combined discharge of the contents M for one time. At the same time, the bag making and packaging machine 20
0 also stops the packaging operation. Accordingly, the delivery of the product M1 to the weight checker 300 is delayed, and after a few seconds, an empty state occurs in which the product M1 indicated by a broken line in FIG. At this time, the zero point adjusting means 31d of FIG.
Calculates the new zero-point weight based on the zero-point signal of the empty conveyor 310 (FIG. 7) and updates and stores the new zero-point weight in the zero-point weight storage unit 33e. Make adjustments.

As described above, when it is determined that the zero point defect has occurred, the combination M
Can be stopped to perform zero point adjustment. Therefore, high weighing accuracy of the weight checker 300 can be maintained without substantially lowering the operation efficiency of the system.

After the zero point adjustment in step S2, the process proceeds to step S3. In step S3, the CPU 31 reads the current and previous zero-point weights from the zero-point weight storage unit 33e, and subtracts the previous zero-point weight from the newly calculated new zero-point weight to obtain a fluctuation value Wo.
Proceed to 4. In step S4, the weighing deviation (Wa─Wb)
The CPU 31 determines whether or not the value obtained by subtracting the fluctuation value Wo from the value is within the allowable value Wp.

Here, if a zero point defect has occurred,
Since the post-measurement average value Wb should have fluctuated by the fluctuation value Wo, the fluctuation value Wo and the value of the measurement deviation (Wa─Wb) should originally match. Therefore, if the result of subtracting the variation value Wo from the weighing deviation (Wa─Wb) is within the allowable value Wp, it can be determined that a zero point defect has occurred. On the other hand, when the subtraction result exceeds the allowable value Wp, it can be determined that there is a possibility that an abnormality has occurred in the combination weighing device 1 instead of the zero point failure. Therefore, when the subtraction result is smaller than the allowable value Wp, the CPU 31 determines that a zero point defect has occurred, and proceeds to step S5. On the other hand, if the subtraction result is equal to or greater than the allowable value Wp, the CPU 31 determines that the combination weighing device 1 may be abnormal, and proceeds to step S6.

In step S5, the CPU 31 causes the touch screen 34 to output contents such as "Zero adjustment has been performed" and the time at which the zero adjustment was performed and the fluctuation value Wo are stored in the RAM 33 in a predetermined manner. It is stored in the storage unit. In step S6, the CPU 31 causes the touch screen 34 to display contents such as "Is there an abnormality in the combination weighing device?"

In the present invention, the allowable value storage unit 33 shown in FIG.
Although d is provided in the RAM 33, d may be stored in a program in the ROM 32. Further, a different value from the allowable value Wp in step S1 of FIG. 5 and the allowable value (predetermined value) Wp in step S4 may be used. As shown in FIG. 6, the first comparing unit 31b, the determining unit 31c, the weight history storage unit 33b, the average value storage unit 33c, and the allowable value storage unit 3
The remote controller 15 having the functions of the 3d and zero point weight storage unit 33e is provided independently of the checker control unit 30, and the checker control unit 30 and the combination controller 10
They may be connected to each other via an interface (not shown).

[0032]

As described above, according to the weight checker of the present invention, the information on the weighing value of the product measured by the weight checker is compared with the information on the weighing value measured by another weighing device. If the comparison result deviates from the previously stored allowable value, it is determined that the weight checker may have a zero point defect. Therefore, it is possible to determine the zero point failure without significantly lowering the operating efficiency of the weight checker.

If it is determined that there is a possibility that a zero point defect may have occurred, the operation efficiency is substantially reduced by delaying the loading of the goods into the weight checker and performing the zero point adjustment. Without this, high weighing accuracy of the weight checker can be maintained.

Further, if the error before the zero point adjustment is compared with the weighing difference between the two weighing values after the zero point adjustment, if the zero point of the weight checker is abnormal, or if another weighting device is used. It can be determined whether there is an abnormality, and a display corresponding to the situation can be output.

[Brief description of the drawings]

FIG. 1 is a schematic side view of a weighing and packaging inspection system according to an embodiment of the present invention.

FIG. 2 is a conceptual diagram illustrating functions of a combination weighing device.

FIG. 3 is a schematic configuration diagram showing a main part of the present invention.

FIG. 4 is a table showing storage contents of a weight history storage unit and an average value storage unit.

FIG. 5 is a flowchart showing a zero point adjustment mode.

FIG. 6 is a schematic configuration diagram of a main part in a modified example.

FIG. 7 is a schematic side view showing the weight checker at the time of zero point adjustment.

[Explanation of symbols]

 M1: Commodity 310: Conveyor 300: Weight checker 1: Combination weighing device (other weighing device) 31f: Second comparison unit 31c: Judgment unit 33b: Weight history storage unit (storage unit) Wa: Combination average value Wb: Post-weighing Average value

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Yasushi Yamaguchi 44th Shonoin Sannocho, Sakyo-ku, Kyoto F-term in Ishida Co., Ltd. (reference) 3F037 AA08 BA05 BA15

Claims (6)

[Claims] 1. A weight checker for determining the acceptability of a product by measuring the weight of the product while conveying the product on a conveyor, comprising: information on a weighing value of the product measured by the weight checker; and another weighing device. Comparing means for comparing information on the weighed value measured in the step (a), and determining means for determining that there is a possibility that the weight checker may have a zero point defect when the comparison result by the comparing means deviates from an allowable value. And a weight checker. 2. The weight checker according to claim 1, wherein information on the weighing values of a plurality of products is used as the information on the weighing values. 3. The weight checker according to claim 1, wherein the weight checker has storage means for storing a plurality of pieces of information relating to weighing values input from another weighing device, and comparing the two weighing values of the product. And a weight checker for reading a corresponding weighing value from the storage means. 4. The weight checker according to claim 1, wherein an average value obtained by averaging weighing values of a plurality of commodities is used as the information on the weighing value. 5. The method according to claim 1, wherein when it is determined that there is a possibility that the zero point defect has occurred, the delivery of the goods to the weight checker is delayed while the goods are not carried in. A weight checker wherein the weight checker performs a zero point adjustment. 6. The method according to claim 5, wherein an error before the zero point adjustment is compared with a weighing difference between the two weighed values after the zero point adjustment, and when the comparison result is out of a predetermined value range, A weight checker that outputs a display according to the situation.