JP2006090711A - Combination metering apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a combination metering apparatus capable of setting an appropriate zero point and preventing undesired consumption of objects to be measured even if residual objects to be measured remain in a scale hopper when zero-point correction is processed. <P>SOLUTION: After objects to be measured selected by combined operation is discharged, it is determined whether a measured value of the scale hopper is present within a first allowable range to a present zero point (S8). In the case that it is present within the first allowable range as a result, zero-point correction of the scale hopper is performed (S9). When not present within the first allowable range, objects to be measured are injected into the scale hopper, and the scale hopper is designated as a precedence hopper to be invariably selected in the following combined operation (S14 and S15). After the precedence hopper is selected by the following combined operation and objects to be measured are discharged, it is determined whether a measured value of the precedence hopper is present within the first allowable range to a present zero point (S8). When present within the first allowable range as a result, zero-point correction of the precedence hopper is performed (S9). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a combination weighing device having a function of automatically performing zero point correction during operation.

  Conventionally, in a weighing device such as a combination weighing device, an analog signal obtained from a weight sensor that detects the weight of an object to be weighed is amplified and A / D converted by a signal processing circuit to display the weight. A digital signal (metric value) is generated. Here, it is known that a zero point drift occurs due to a temperature change of the weight sensor itself or a temperature change of a signal processing circuit that performs amplification and A / D conversion. Since such a drift appears as an error in the measured value, a function for automatically correcting the zero point is provided in order to ensure the accuracy of the measured value.

For example, Patent Document 1 and Patent Document 2 disclose conventional techniques for performing automatic zero correction. When the zero point correction is performed, the technique of Patent Document 1 may be caused by a person or an object touching the scale if the measurement signal deviates greatly from the signal corresponding to the zero point. Therefore, the same state as before the zero point correction is made, that is, the zero point correction is not performed. Further, in the technique of Patent Document 2, when the zero point correction is performed, if the weighing signal deviates greatly from the signal corresponding to the zero point, the object to be weighed is caught in the gate of the weighing hopper. If this is the case, the cause may be that the object to be weighed adheres to the weighing hopper, so remove the cause by reopening the weighing hopper and then perform zero correction again. I have to.
JP-A-57-30912 Japanese Patent No. 2552440

  In the combination weighing device, the cause of the large deviation of the zero point is often the object to be weighed into the gate of the supply hopper arranged above the weighing hopper in order to put the object to be weighed into the weighing hopper. In this case, the zero point correction is performed in a state where the object to be weighed has dropped into the weighing hopper due to vibration or the like, or in a state where the object to be weighed is caught in the gate of the weighing hopper. If zero correction is performed in such a state, an erroneous zero point is set until the next zero correction is performed, and whenever the weighing hopper participates in the combination and is discharged, the staying weighing object The weight of the object to be weighed that has dropped from the supply hopper to the weighing hopper and the object to be weighed by the gate of the weighing hopper is discharged.

  In order to prevent this, when the technique of Patent Document 1 is used, there is a problem that even if the zero point is actually shifted, zero point correction is not performed and erroneous weighing occurs. Further, when the technique of Patent Document 2 is used, the above-mentioned stay-weighed object is discharged by reopening the weighing hopper, but the object to be weighed discharged from the combination weighing device is packaged as shown in FIG. When it is supplied to the machine and packed in a bag, the staying weighing object is discharged into the next bag, and the next bag is filled with much weighing object, and unnecessary consumption of the weighing object. There is a problem that occurs.

  The present invention has been made in order to solve the above-described problems, and even when a staying object is generated in the weighing hopper during the zero correction process, an appropriate zero can be set and is unnecessary. An object of the present invention is to provide a combination weighing device that can prevent consumption of an object to be weighed.

  In order to solve the above-mentioned problems, a combination weighing device of the present invention includes a plurality of supply hoppers and a plurality of weighing units that weigh the weights of objects to be weighed that are respectively disposed below the supply hoppers and fed from the supply hoppers. Select the hopper and the weighing hopper to be discharged sequentially by combination calculation, discharge the object to be weighed from the selected weighing hopper, and load the object to be weighed from the supply hopper to the discharged weighing hopper And a control means for performing zero-point correction processing of the weighing hopper every predetermined time, and the zero-point correction processing by the control means is selected after the weighing hopper to be processed is selected by a combination operation, and the object to be weighed is discharged. A process of stopping the input of the object to be weighed from the supply hopper to the weighing hopper to be processed, and the process object of which the input of the object to be weighed has been stopped Based on the first determination process for determining whether or not the weighing value of the quantity hopper is within the first allowable range with respect to the current zero point, and the determination result of the first determination process, When the measurement value of the weighing hopper is within the first allowable range with respect to the current zero point, the zero correction of the weighing hopper to be processed is performed, and the first allowable value with respect to the current zero point is performed. And processing for not performing zero correction of the weighing hopper to be processed when it does not exist within the range.

  Further, the zero point correction processing by the control means may further be such that the measurement value of the weighing hopper to be processed is within the first allowable range with respect to the current zero point based on the determination result by the first determination processing. The processing target weighing hopper is loaded with the object to be weighed from the supply hopper, and the processing target weighing hopper is designated as a priority hopper that is always selected in the next combination calculation.

  Further, the zero point correction processing by the control means further stops the feeding of the weighing object from the supply hopper to the priority hopper after the weighing object is discharged after the priority hopper is selected by the next combination calculation. And a second determination process for determining whether or not the measured value of the priority hopper for which the input of the object to be weighed has stopped is within the first allowable range with respect to the current zero point. A process of correcting the zero point of the priority hopper when the measured value of the priority hopper is within the first allowable range with respect to the current zero point based on the determination result of the second determination process; including.

  According to the above configuration, if the measurement value of the weighing hopper to be processed is not within the first allowable range with respect to the current zero as a result of the first determination process, the zero correction is not performed and the process is performed. The target weighing hopper is designated as the priority hopper and is selected by the next combination calculation, and the second determination process same as the first determination process is performed. As a result of the second determination process, the measurement value of the priority hopper is The zero point of the priority hopper is corrected when the zero point is within the first permissible range, and the object to be weighed (from the supply hopper to the weighing hopper) Of the weighing hopper or the weighing object that has been caught in the gate of the weighing hopper), and the weighing value of the weighing hopper does not exist within the first allowable range with respect to the current zero point. Does not perform zero point correction, It can be prevented but is set. Then, the stay weighing object is discharged by the discharging operation after the next combination calculation, and then an appropriate zero point is set by performing zero point correction. In the above “next combination calculation”, the combination is performed using the measurement value including the weight of the staying weighing object, so that the staying weighing object is divided into the next bag (packaging machine bag). Therefore, it is possible to prevent unnecessary consumption of objects to be weighed such that only a large number of objects to be weighed are filled.

  In the zero point correction process by the control means, the measured value of the priority hopper does not exist within the first allowable range with respect to the current zero point based on the determination result by the second determination process. In this case, a difference between the measurement value of the weighing hopper to be processed used in the first determination process and the measurement value of the priority hopper used in the second determination process is greater than the first allowable range. When the difference exists in the second allowable range based on the third determination process for determining whether or not the second allowable range is narrow and the determination result of the third determination process. And a process of correcting the zero point of the priority hopper.

  Thereby, even if the weighing value in the empty state of the same weighing hopper in the first determination process and the second determination process does not exist within the first allowable range with respect to the current zero point, the third determination process Based on the result, zero correction can be performed and normal operation can be continued.

  The zero point correction process by the control unit further outputs an abnormal signal from the control unit when the difference does not exist within the second allowable range based on the determination result by the third determination process. In addition, there may be provided notifying means for notifying that the priority hopper is abnormal based on the abnormality signal, including a process for preventing the priority hopper from being selected by a combination calculation.

  Accordingly, it is possible to notify the operator that the weighing hopper designated as the priority hopper is abnormal, and it is possible to prevent erroneous weighing using the weighing hopper.

  The present invention has the above-described configuration. In the combination weighing device, an appropriate zero point can be set even if a staying object is generated in the weighing hopper during the zero point correction process, and is unnecessary. There is an effect that consumption of the objects to be weighed can be prevented.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
(Embodiment)
FIG. 1 is a schematic diagram showing a configuration of a combination weighing device according to an embodiment of the present invention.

  In the combination weighing device according to the present embodiment, a conical dispersion feeder 11 is provided in the center of the upper portion of the device to disperse the object to be weighed supplied from the external supply device 10 radially by vibration. Around the dispersion feeder 11, linear feeders 12 are provided for feeding the objects to be weighed sent from the dispersion feeder 11 to the respective supply hoppers 13 by vibration. Below the linear feeder 12, a plurality of supply hoppers 13, weighing hoppers 14, and memory hoppers 15 are provided correspondingly and arranged in a circular shape. The supply hopper 13 receives the object to be weighed sent from the linear feeder 12, and when the weighing hopper 14 disposed below it is empty, the gate is opened and the object to be weighed is put into the weighing hopper 14. A weight sensor 19 such as a load cell is attached to the weighing hopper 14, and the weight sensor 19 measures the weight of an object to be weighed in the weighing hopper 14. Here, the weighing hopper 14 is configured so that the objects to be weighed can be selectively discharged to the memory hopper 15 and the collecting chute 16. The memory hopper 15 is disposed obliquely below the weighing hopper 14, and an object to be weighed is inserted from the weighing hopper 14 when empty. A combination of hoppers (hereinafter referred to as discharge hoppers) to be discharged from a plurality of weighing hoppers 14 and memory hoppers 15 is obtained by combination calculation by the control unit 21, and the objects to be weighed are collected from the discharge hoppers corresponding to the combinations by the collecting chute 16. Discharged to the top. The collective chute 16 is provided below the weighing hopper 14 and the memory hopper 15, and a collective funnel 17 is disposed below the collective chute 16. The objects to be weighed discharged from the weighing hopper 14 and the memory hopper 15 are collected on the collecting chute 16 by the collecting funnel 17 and temporarily stored in the collecting hopper 18. In response to a discharge request signal from a packaging machine (not shown), the control unit 21 opens the gate of the collecting hopper 18 and sends the objects to be weighed to the packaging machine. In addition, a photoelectric level sensor 20 that detects the amount of an object to be weighed on the dispersion feeder 11 is provided, and the control unit 21 sets the object to be weighed on the dispersion feeder 11 to a certain amount based on a signal from the level sensor 20. The supply device 10 is controlled to keep.

  The control unit 21 includes an I / O unit 210, a CPU 211, a memory 212, a timer 213, and the like. The control unit 21 performs the above-described control of the supply device 10, the overall control of the combination weighing device, and the combination calculation. In the combination calculation, one hopper combination is obtained from the plurality of weighing hoppers 14 and the memory hopper 15 so that the sum of the measured values of the objects to be weighed is within the allowable range with respect to the target weight. When there are a plurality of combinations of hoppers that fall within the allowable range, for example, one combination is selected from the plurality of combinations, for example, the sum of the measured values of the objects to be weighed is closest to the target weight. In this combination calculation, the measured value by the weight sensor 19 is used as the measured value of the object to be weighed in the weighing hopper 14, and the measured value of the object to be weighed in the memory hopper 15 is weighted by the weighing hopper 14 above it. The value measured by the sensor 19 is held in the memory 212 inside the control unit 21, and the value is used.

  An outline of the operation of the combination weighing device according to the present embodiment configured as described above will be described first. The operation of the combination weighing device is realized by the control of the control unit 21.

  First, the objects to be weighed are conveyed above the combination weighing device by the supply device 10 and placed on the dispersion feeder 11. Then, the objects to be weighed are sent to the supply hoppers 13 which are radially dispersed by the vibration of the dispersion feeder 11 and arranged in a plurality of circles via the linear feeder 12 following the dispersion feeder 11. When the weighing hoppers 14 located below the supply hoppers 13 are empty, the objects to be weighed in the supply hoppers 13 are put into the weighing hoppers 14. In addition, when the memory hopper 15 located below each weighing hopper 14 is empty, an object to be weighed in each weighing hopper 14 is put into the memory hopper 15. When the control unit 21 determines the discharge hopper from the weighing hopper 14 and the memory hopper 15 from the result of the combination calculation, the control unit 21 causes the discharge hopper to discharge the objects to be weighed onto the collecting chute 16. The objects to be weighed are collected on the collecting chute 16 by the collecting funnel 17 and temporarily stored in the collecting hopper 18. The control unit 21 receives the discharge request signal from the packaging machine, opens the gate of the collecting hopper 18, and sends the objects to be weighed to the packaging machine.

  FIG. 2 shows an example of a timing chart of the gate opening / closing operation of the memory hopper 15, the weighing hopper 14, and the supply hopper 13 and the vibration operation of the linear feeder 12 that are provided correspondingly. When the memory hopper 15 is determined as the discharge hopper by the combination operation and the gate opening / closing operation is performed, the weighing hopper 14 opens the gate starting from the time when the gate of the memory hopper 15 starts to close, and the memory hopper 15 is to be weighed. The supply hopper 13 opens the gate starting from the time when the gate of the weighing hopper 14 starts to close and supplies the object to be weighed to the weighing hopper 14, and the linear feeder 12 is connected to the gate of the supply hopper 13. Then, a vibrating operation is performed starting from the time point at which closing starts, and the object to be weighed is supplied to the supply hopper 13. As described above, the weighing hopper 14, the supply hopper 13, and the linear feeder 12 start their operations starting from the time when the gates of the respective lower hoppers start to close, thereby improving the ability of the combination weighing device. Also, the delay times Td1, Td2, and Td3 are provided because the objects to be weighed from above arrive before the gates of the respective lower hoppers are completely closed, and the objects to be weighed in the gates. This is in order to prevent the occurrence of the object and the object to be weighed from passing through the hopper, but the measuring ability can be improved by shortening the delay times Td1, Td2 and Td3.

  In some cases, the collection hopper 18 is not provided. In this case, the control unit 21 receives the discharge request signal from the packaging machine, opens the gate of the discharge hopper, and the objects to be weighed discharged from the discharge hopper are collected into the collection chute. 16 is collected by a sliding funnel 17 and discharged.

  In FIG. 5, the outline of a structure of the packaging machine installed under the combination weighing | measuring apparatus in this Embodiment is shown. This packaging machine fills and packs the objects to be weighed discharged from the combination weighing device while manufacturing the bags. In this packaging machine, a sheet-like packaging material 50 drawn from a roll of packaging material is wound around a tube 51 by a former 52 and formed into a cylindrical shape, and is adsorbed by a pull-down belt machine 53 and sent downward. The stacked vertical edges of the packaged packaging material 50 are sealed (sealed by welding) by the vertical sealing machine 54. Then, the objects to be weighed discharged from the combination weighing device are filled into the cylindrical packaging material 50 through the tube 51, and the upper end of the preceding bag and the succeeding bag are placed by the horizontal sealing machine 55 disposed below the tube 51. A lateral seal (sealing by welding) is performed across the lower end of the bag. By performing the horizontal sealing, the preceding bag becomes a complete bag whose upper and lower sides are sealed because the lower end is sealed by the previous horizontal sealing. Then, the center of the horizontal seal portion is cut by a cutter built in the horizontal sealing machine 55, and the preceding bag and the subsequent bag are separated.

  Next, detailed operation of the combination weighing device in the present embodiment will be described. FIG. 3 shows a flowchart of the operation of the combination weighing device in the present embodiment. Note that a zero point correction flag, a previous abnormality flag, and a balance stabilization time-up flag, which will be described later, are provided corresponding to each weighing hopper 14 and set in the respective flag areas in the memory 212.

  In step S1, the combination calculation is performed as described above, and the object to be weighed is discharged from the discharge hopper determined by the combination calculation. Next, in step S2, it is determined whether the zero point correction flag is set and whether there is a weighing hopper 14 (hereinafter, the corresponding weighing hopper 14) that has become the discharge hopper in step S1. If there is the corresponding weighing hopper 14, the process proceeds to step S3, the charging of the object to be weighed from the supply hopper 13 to the corresponding weighing hopper 14 is stopped, and a predetermined weighing stabilization time of the corresponding weighing hopper 14 is set in the timer 213 ( Step S4).

  FIG. 4 is a flowchart of a timer control program (time control routine) that is activated at regular time intervals (for example, 1 msec). The zero point correction flag corresponding to each weighing hopper 14 is set every predetermined time (zero point correction interval time) in steps S31 to S33, and the weighing stable time up flag corresponding to the corresponding weighing hopper 14 is set to step S34 to step S34. By S37, it is set after the elapse of the predetermined weighing time set in the timer 213 in step S4.

  In step S5 of FIG. 3, it is checked whether or not the weighing stability time up flag of the weighing hopper 14 for which the zero point correction flag is set is set. If the balance stabilization time-up flag is set, the measurement value (hereinafter referred to as zero measurement value) by the weight sensor 19 for the corresponding weighing hopper 14 in an empty state is read (step S6). The stable time-up flag is reset (step S7). Next, in step S8, it is determined whether or not the zero measurement value read in step S6 is within the allowable range A. If it is within the allowable range A, zero correction is performed (step S9), and the zero correction flag and the previous time are determined. The abnormality flag is reset (step S10). The zero correction in step S9 is a process for resetting the zero measurement value read in step S6 to a new zero. The allowable range A is based on the current zero point before the zero correction in step S9 as a reference, and the zero point fluctuation range due to drift or the like normally predicted within the zero point correction interval time and the expected measurement error due to disturbance such as airflow. It is set as an added range. If the object to be weighed falls from the upper supply hopper 13 to the corresponding weighing hopper 14 or the object to be weighed is caught in the gate of the corresponding weighing hopper 14, the zero-point measured value is outside the allowable range A. In each weighing hopper 14, until the first zero correction is performed from when the power is turned on, the preset zero is the current zero, and thereafter, the zero reset by the previous zero correction is the current zero. This is the zero point.

  In step S8, if the zero measurement value is outside the allowable range A, the process proceeds to step S11, and it is checked whether or not the previous abnormality flag for the measurement hopper is set. In the first case, since the previous abnormality flag is not set, the process proceeds to step S12, the previous abnormality flag is set, the measurement value in the empty state is stored in the memory 212 (step S13), and the corresponding measurement is performed from the supply hopper 13. An input instruction for inputting an object to be weighed into the hopper 14 is issued (step S14), and the corresponding weighing hopper 14 is set as a priority hopper (step S15). Here, the priority hopper is always selected as the discharge hopper in the next combination calculation.

  After step S15, the next combination calculation is performed in step S1, the object to be weighed is discharged from the discharge hopper, and then steps S2 to S8 are executed. In step S8, if the zero-point measured value read in step S6 is within the allowable range A, steps S9 and S10 are executed, and zero correction is performed. In this case, the zero-point measured value, which is the measured value in the empty state of the corresponding weighing hopper 14, is outside the allowable range A in the previous determination in step S8, and is in the allowable range A in the current determination in step S8. In the previous case, it is considered that the object to be weighed dropped from the upper supply hopper 13 to the corresponding weighing hopper 14 or that the object to be weighed was caught in the gate of the corresponding weighing hopper 14. By not performing the operation, it is possible to prevent an erroneous zero point from being set. Then, such a stay-weighed object (an object to be weighed that has dropped from the supply hopper 13 to the corresponding weighing hopper 14 or an object to be weighed by the gate of the corresponding weighing hopper 14) is discharged after the next combination calculation. It is discharged by the operation, and then the zero point correction in step S9 is performed to set an appropriate zero point. According to this flow, since the above “next combination calculation” is performed using the measured value including the weight of the stay weighed object, the inside of the next bag of the packaging machine filled with the stay weighed object is included. The weight of the object to be weighed is the normal weight (allowable range of the target weight). Consumption can be prevented.

  On the other hand, if the determination in step S8 is outside the allowable range A, the process proceeds to step S11, and the previous abnormality flag is set. Therefore, the process proceeds to step S16, and the previous zero value and the current zero value are determined. It is determined whether or not the difference is within the allowable range B. If the difference is within the allowable range B, zero correction is performed using the current zero measurement value (step S17), and the zero correction flag and the previous abnormality flag are reset. (Step S18). If it is determined in step S16 that the difference between the previous zero measurement value and the current zero measurement value is outside the allowable range B, an alarm indicating an abnormality of the corresponding measurement hopper 14 is displayed (step S19). The head including the weighing hopper 14 is disabled (rested) (step S20). The head is a unit composed of a linear feeder 12, a supply hopper 13, a weighing hopper 14, a memory hopper 15, a weight sensor 19 and the like provided in correspondence. The abnormal alarm in step S19 is displayed on, for example, an operation setting display (not shown) for operating the combination weighing device and displaying a set value such as an operation speed. The operator can be notified that the corresponding weighing hopper 14 is abnormal by the process of step S19, and erroneous weighing using the corresponding weighing hopper 14 can be prevented by the process of step S20.

  In the allowable range B in step S16, an expected measurement error due to a disturbance such as an air current is added to a fluctuation range of a zero point due to a drift or the like normally predicted within a time period from the previous measurement to the next current measurement. It is a range. Normally, the fluctuation range of the zero point due to a drift or the like tends to increase with the passage of time after the power is turned on, and the time from the previous measurement to the next next measurement considered in the allowable range B (for example, about The fluctuation range of the zero point due to the drift or the like normally predicted within 1 second) is narrower than the fluctuation range of the zero point due to the drift or the like normally expected within the zero correction interval time (for example, 60 seconds) considered in the allowable range A. It is a range. Therefore, the allowable range B is set to be narrower than the allowable range A. For example, the permissible range B may be set to about 1/5 of the permissible range A, depending on how the expected measurement error is caused by disturbances such as airflow. The zero point correction interval time may be changed within a predetermined time after the power is turned on and after the predetermined time has elapsed, and the allowable range A may also be changed according to the zero point correction interval time. For example, after the power is turned on, the zero point correction interval time is set to 1 minute for 10 minutes and the allowable range A is set to A1, and after 10 minutes, the zero point correction interval time is changed to 5 minutes and the allowable range A is set to A2 (A2> A1). ) May be changed.

  When executing step S17 and step S18, it is a case where it is determined that it is outside the allowable range A in step S8, and it is determined that it is within the allowable range B in step S16. . Experience shows that there is almost no occurrence of staying objects twice for the same weighing hopper 14, so it is determined that the value is outside the allowable range A in step S8 twice in the previous time and this time. In addition, if it is within the permissible range B in step S16, a zero point fluctuation that is normally expected is generated, and zero point correction is performed in step S17. For example, even if there is no occurrence of staying objects, if the allowable range A is set strictly (narrowly), it is determined that the allowable range A is outside the allowable range A in step S8 twice in succession and the previous time. In that case, if the condition of step S16 is satisfied, the zero point correction is performed, so that a normal operation is possible, and the abnormal processing of steps S19 and S20 can be avoided. In this flow, zero point correction (step S17) is performed even when the same amount of staying objects is generated twice for the same weighing hopper 14, but as described above. Experience shows that there is almost no problem of staying objects being measured twice for the same weighing hopper 14, and there is almost no problem in practical use.

  Although the combination weighing device of the present embodiment includes the memory hopper 15, it is needless to say that the present invention can be similarly applied even when the memory hopper 15 is not provided.

  INDUSTRIAL APPLICABILITY The present invention is useful as a combination weighing device that can set an appropriate zero point even when a staying object is generated in the weighing hopper when zero correction is automatically performed during operation.

It is a schematic diagram which shows the structure of the combination weighing | measuring apparatus in embodiment of this invention. It is a timing chart of the opening / closing operation | movement of the memory hopper of the combination weighing | measuring apparatus in embodiment of this invention, the weighing hopper, and the supply hopper, and the vibration operation | movement of a linear feeder. It is a flowchart of operation | movement of the combination weighing | measuring apparatus in embodiment of this invention. It is a flowchart of the timer control program (time control routine) of the combination weighing | measuring apparatus in embodiment of this invention. It is a schematic diagram which shows the structure of the packaging machine installed under the combination weighing | measuring apparatus in embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Supply apparatus 11 Dispersion feeder 12 Linear feeder 13 Supply hopper 14 Weighing hopper 15 Memory hopper 16 Collecting chute 17 Collecting funnel 18 Collecting hopper 19 Weight sensor 20 Level sensor 21 Control part

Claims (5)

A plurality of supply hoppers;
A plurality of weighing hoppers that are respectively disposed below the supply hopper and measure the weight of an object to be weighed introduced from the supply hopper;
Sequentially, the weighing hopper to be discharged by a combination operation is selected, the object to be weighed is discharged from the selected weighing hopper, the object to be weighed is input from the supply hopper to the discharged weighing hopper, and Control means for performing zero point correction processing of the weighing hopper every time,
The zero point correction processing by the control means is
A process for stopping the weighing object from being fed from the supply hopper to the weighing hopper to be processed after the weighing hopper to be processed is selected by a combination operation and discharging the weighing object;
A first determination process for determining whether or not a measured value of the processing target weighing hopper that has been stopped to be charged is within a first allowable range with respect to a current zero point;
Based on the determination result of the first determination process, when the measured value of the weighing hopper to be processed is within the first allowable range with respect to the current zero, the zero of the weighing hopper to be processed A combination weighing apparatus including a process of performing correction and not performing zero correction of the weighing hopper to be processed when the current zero is not within the first allowable range. The zero point correction processing by the control means further includes:
When the measurement value of the weighing hopper to be processed is not within the first allowable range with respect to the current zero point based on the determination result of the first determination process, the weighing hopper to be processed The combination weighing device according to claim 1, further comprising a process of loading an object to be weighed from the supply hopper and designating the weighing hopper to be processed as a priority hopper that is always selected in the next combination calculation. The zero point correction processing by the control means further includes:
The priority hopper is selected by the next combination calculation, and after discharging the object to be weighed, a process of stopping the input of the object to be weighed from the supply hopper to the priority hopper;
A second determination process for determining whether or not the measured value of the priority hopper that has been stopped to be charged is within the first allowable range with respect to the current zero point;
A process of correcting the zero point of the priority hopper when the measured value of the priority hopper is within the first allowable range with respect to the current zero point based on the determination result of the second determination process. The combination weighing device according to claim 2 including. The zero point correction processing by the control means further includes:
When the measured value of the priority hopper is not within the first allowable range with respect to the current zero point based on the determination result by the second determination process, Whether or not the difference between the weighing value of the weighing hopper to be processed and the weighing value of the priority hopper used in the second determination process is within a second allowable range that is narrower than the first allowable range. A third determination process for determining;
The combination weighing device according to claim 3, further comprising a process of correcting a zero point of the priority hopper when the difference is within the second allowable range based on a determination result obtained by the third determination process. The zero point correction processing by the control means further includes:
When the difference does not exist within the second allowable range based on the determination result of the third determination process, an abnormal signal is output from the control unit so that the priority hopper is not selected by a combination operation. Including processing,
The combination weighing device according to claim 4, further comprising a notification unit configured to notify that the priority hopper is abnormal based on the abnormality signal.

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