Combination weighing device

Abstract

If the standby state of the combination weighing device is prolonged, the reliability of the weighed values ​​of the items in the hopper decreases. [Solution] When the combined weighing control unit restarts operation after a predetermined period of time in a first state in which it does not send a discharge command to the target hopper, it corrects the second weighing value based on the difference and performs a combined calculation until zeroing is performed in the weighing unit corresponding to the target hopper. The difference is the difference between the first weighing value acquired by the weighing unit before the restart of operation and the second weighing value acquired by the weighing unit after the restart of operation.

Description

Technical Field

[0001] The present invention relates to a combination weighing device.

Background Art

[0002] As disclosed in Patent Document 1 (Japanese Patent Application Laid-Open No. 2001-2013), a system having a weighing device and a bag-making and packaging device for bagging the articles weighed by the weighing device is provided in the production line of bagged products. In this system, when the combination of the weighing devices fails continuously, the weighing hopper is forcibly opened, and a process of discharging all the articles in all the weighing hoppers and bagging them (total discharge process) is performed.

Summary of the Invention

Problems to be Solved by the Invention

[0003] During the operation of the combination weighing device, when the supply device on the upstream side that supplies articles to the combination weighing device stops, or when the discharge instruction of articles from the downstream bag-making and packaging device does not reach the combination weighing device, the combination weighing device enters a standby state. If this standby state lasts for a long time, the temperature near the hopper and the weighing unit changes, or additional articles enter the hopper, resulting in a decrease in the reliability of the measured values of the articles in the hopper. As one countermeasure against this, the above total discharge process is performed to empty the hopper once, but normal operation cannot be resumed while the total discharge process is being performed, and the operating rate of the production line decreases.

Means for Solving the Problems

[0004] The combination weighing device relating to the first aspect comprises a plurality of hoppers, a plurality of weighing units, and a control unit. Each of the plurality of hoppers stores the items that are put in and discharges the items according to a discharge instruction. A weighing unit is provided corresponding to each of the plurality of hoppers. Each of the plurality of weighing units acquires the mass of the items stored in the corresponding hopper as a weighed value. The control unit performs a combination calculation using the plurality of weighed values. The control unit sends a discharge instruction to one or more hoppers determined by the combination calculation. If the control unit restarts operation after the first state has continued for a predetermined time, it corrects the second weighed value based on the difference and performs a combination calculation until zeroing is performed in the weighing unit corresponding to the target hopper. The first state is a state in which no discharge instruction is sent to the target hopper. The difference for correcting the second weighed value is the difference between the first weighed value acquired by the weighing unit before the restart of operation and the second weighed value acquired by the weighing unit after the restart of operation.

[0005] In the combination weighing device relating to the first aspect, if the control unit does not send a discharge command to the target hopper (first state) for a predetermined period of time, a decrease in the reliability of the weighed value occurs, for example, due to temperature changes in the weighing unit. In view of this, when operation is restarted, the control unit corrects the second weighed value based on the difference until zeroing is performed in the weighing unit corresponding to the target hopper. This eliminates to some extent the decrease in the reliability of the weighed value that occurred during the predetermined period of time, and when operation is restarted, combination calculations can be performed using weighed values ​​with a certain degree of reliability.

[0006] The first state includes states where the supply of goods from another device upstream of the combined weighing device has stopped, where requests for the discharge of weighed items from another device downstream of the combined weighing device have stopped, and where the combined weighing device is stopped or in standby mode due to manual operation.

[0007] The combination weighing device relating to the second perspective is the combination weighing device relating to the first perspective, wherein the control unit receives weighing values ​​from the weighing unit at first time intervals while the first state continues for a predetermined time. The control unit also determines whether or not there is an abnormality in the hopper based on the weighing values ​​received from the weighing unit.

[0008] In the combination weighing device relating to the second perspective, by adopting a configuration in which the weighing value is acquired from the weighing unit while the first state continues for a predetermined time, it is possible to determine whether or not there is an abnormality in the hopper.

[0009] The combination weighing device relating to the third perspective is the combination weighing device relating to the second perspective, wherein if the control unit determines that there is an abnormality in the hopper, it removes the weighing value obtained by the weighing unit corresponding to the hopper that was determined to have an abnormality from the multiple weighing values ​​used in the combination calculation after the restart of operation.

[0010] In the combination weighing device relating to the third aspect, the weighing result (weighing value) of the items in the abnormal hopper is excluded from the multiple weighing values ​​used in the combination calculation after operation is resumed. This improves the accuracy of the combination calculation results.

[0011] The combination weighing device relating to the fourth perspective is a combination weighing device relating to either the first or third perspective, wherein the control unit has the first weighing unit, which corresponds to the first hopper from which the goods were discharged after the restart of operation, and the second weighing unit, which corresponds to the second hopper from which the goods were discharged after the restart of operation, perform zeroing, but does not have the second weighing unit perform zeroing. Furthermore, in the combination calculation, the control unit continues to make corrections based on the difference in weighing values ​​acquired by the second weighing unit.

[0012] In the combination weighing device relating to the fourth aspect, zeroing is not performed on the second weighing unit corresponding to the second hopper from which the goods were discharged after the restart of operation. Therefore, the reliability of the next weighing value from the second weighing unit is low. In view of this, the control unit continues to correct the combination calculation using the difference in weighing values ​​acquired by the second weighing unit, thereby maintaining the accuracy of the combination calculation.

[0013] Furthermore, in the combined weighing device relating to the fourth perspective, after the restart of operation, the first weighing unit corresponding to the hopper from which the goods were discharged is subjected to zeroing, while the second weighing unit is not subjected to zeroing. Therefore, compared to the case where all weighing units corresponding to the hopper from which the goods were discharged are subject to zeroing after the restart of operation, the combined weighing device relating to the fourth perspective can secure a larger number of weighing units (weighing values) that can participate in the combined calculation.

[0014] The combination weighing device relating to the fifth perspective is a combination weighing device relating to either the first or third perspective, and the control unit causes the weighing unit corresponding to all hoppers from which the goods were discharged to perform zeroing after the restart of operation.

[0015] In the combination weighing device relating to the fifth perspective, after operation is resumed, all weighing units corresponding to hoppers from which goods have been discharged are subject to zeroing. Therefore, although there is a disadvantage in that many weighing units will be subject to zeroing for a while after operation is resumed, there is an advantage in that the process of correcting the second weighing value based on the difference and performing combination calculations is completed earlier.

[0016] The combination weighing device relating to the sixth perspective is the combination weighing device relating to the second perspective, and if the control unit determines that there is an abnormality in a hopper, after restarting operation, it either does not perform a correction based on the difference corresponding to the hopper in question for the second weighing value corresponding to the hopper in question, or it performs a correction based on the difference corresponding to other hoppers that are determined to be free of abnormalities. In the latter case, for example, the second weighing value corresponding to the hopper in question is corrected based on the average value of the differences corresponding to several other hoppers that are determined to be free of abnormalities. [Effects of the Invention]

[0017] In a combination weighing device, if the first state continues for a predetermined time, there is a risk that the reliability of the weighing value may decrease due to, for example, a temperature change in the weighing unit. However, according to the present invention, until zero-point processing is performed in the weighing unit corresponding to the target hopper, the second weighing value is corrected based on the difference. As a result, the decrease in the reliability of the weighing value that occurs during the predetermined time is eliminated to some extent.

Brief Description of the Drawings

[0018] [Figure 1] A diagram showing a schematic configuration of a combination weighing device according to an embodiment of the present invention and devices before and after it. [Figure 2] A diagram showing the concept of combination calculation of a combination weighing device. [Figure 3] A diagram showing a schematic configuration of a bag-making and packaging device. [Figure 4] A control block diagram of a combination weighing device and a bag-making and packaging device. [Figure 5] A block diagram of a combination weighing control unit. [Figure 6] A main control flowchart of a combination weighing device. [Figure 7] A control flowchart of the operation process of a combination weighing device. [Figure 8] A control flowchart of the weighing data preparation process of a combination weighing device. [Figure 9] A control flowchart of the abnormality monitoring process of a combination weighing device.

Embodiments for Carrying Out the Invention

[0019] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The following embodiments are specific examples of the present invention and do not limit the technical scope of the present invention.

[0020] (1) Configuration of a combination weighing device and devices before and after it A combination weighing device 110 according to an embodiment of the present invention, and supply conveyor devices 101 and bag-making and packaging devices 120 before and after it are shown in FIG. 1. Here, the combination weighing device 110 and the bag-making and packaging device 120 are arranged vertically, and an operation display 60 and operation switches 70 are shared (see FIG. 4). In the present embodiment, the article supplied from the supply conveyor device 101 to the combination weighing device 110 is potato chips, and combination weighing is performed in the combination weighing device 110 so that the article has a predetermined weight. The articles aggregated to a weight within a predetermined range by the combination weighing device 110 fall onto the bag-making and packaging device 120 and are bagged in the bag-making and packaging device 120. The bags discharged from the bag-making and packaging device 120 are placed on a conveyor 130 by an inclined guide plate 129 and conveyed to a weight checker 140 in a subsequent process.

[0021] To a control computer 50 for controlling the combination weighing device 110 and the bag-making and packaging device 120, an operation switch 70 arranged on the front surface of the bag-making and packaging device 120 and an operation display 60 visible to an operator are connected. On this operation display 60, a touch panel is overlaid on a display panel, and the operator can operate the combination weighing device 110 and the bag-making and packaging device 120 by touching the operation display 60.

[0022] (2) Configuration of combination weighing device As shown in FIGS. 1 and 2, the combination weighing device 110 mainly includes a conical dispersion feeder 111, a plurality of radial troughs 112, a plurality of pool hoppers 113 and weighing hoppers 114, and a collective discharge chute 115.

[0023] The distributed feeder 111 is positioned directly below the article supply position of the supply conveyor device 101. The radial troughs 112 are each positioned around the distributed feeder 111. The distributed feeder 111 is vibrated by a vibration device. The distributed feeder 111 also has a function to measure the weight of the articles placed on it. Articles supplied from the supply conveyor device 101 to the upper surface of the distributed feeder 111 move towards the radial troughs 112, dispersing due to the vibration. Each radial trough 112 is also vibrated by another vibration device, moving the articles outward and sending them to the pool hopper 113.

[0024] The pool hopper 113 receives goods from the radial trough 112 and temporarily pools them. Then, in response to a command from the control computer 50 (described later), the pool hopper 113 opens the gate located at its bottom and supplies the goods to the weighing hopper 114.

[0025] Each weighing hopper 114 is located below the pool hopper 113. Like the pool hopper 113, multiple weighing hoppers 114 are arranged circumferentially. Each weighing hopper 114 has a load cell 114b (see Figure 5) for measuring the weight of the items in the hopper. Each of the load cells 114b acquires the mass of the items stored in the corresponding weighing hopper 114 as a measured value. Additionally, an opening / closing gate 114a and a motor for opening and closing the gate 114a are provided at the bottom of each weighing hopper 114. When the opening / closing gate 114a opens, the items in the hopper are discharged into the collection discharge chute 115.

[0026] The collective discharge chute 115 collects the items dropped from each weighing hopper 114 and flows them into the tube 122 of the bag-making and packaging device 120.

[0027] (3) Configuration of the bag-making and packaging device The bag-making and packaging device 120 is located below the combined weighing device 110 and, as shown in Figure 3, mainly consists of a former 121, a tube 122, a vertical sealing mechanism 123, a horizontal sealing mechanism 124, and a pull-down belt mechanism 125. The former 121 and tube 122 function as forming mechanisms that shape sheet-like packaging film Fm into a cylindrical shape. The tube 122 is a cylindrical component with openings at its upper and lower ends. Articles discharged from the combined weighing device 110 fall into the opening at the upper end of the tube 122. The pull-down belt mechanism 125 transports the cylindrical film Fmc downwards. The vertical sealing mechanism 123 seals the overlapping portion of the cylindrical film Fmc vertically. The horizontal sealing mechanism 124 seals the cylindrical film Fmc horizontally, thereby closing the upper and lower ends of the bag. Furthermore, the lateral sealing mechanism 124 has a built-in cutter that cuts through the center of the laterally sealed portion, separating bag B from the subsequent tubular film Fmc.

[0028] (4) Control computer The control computer 50 has a CPU (Central Processing Unit), ROM (Read-Only Memory), RAM (Random Access Memory), HDD (Hard Disk Drive), and drives for inserting storage media, etc., and these are interconnected via bus lines such as an address bus and a data bus. The CPU executes various programs stored in the ROM or HDD. As shown in Figure 4, the control computer 50 has as functional units a combination weighing control unit 51 that controls the combination weighing device 110, a bag making and packaging control unit 52 that controls the bag making and packaging device 120, and a main control unit 53 that controls the operation spanning both devices 110 and 120. The combination weighing control unit 51, the bag making and packaging control unit 52, and the main control unit 53 are control sequences or control programs that use the CPU. The main control unit 53 mediates the exchange of timing signals, error signals, weight data, etc. between the two control units 51 and 52. The main control unit 53 also accepts operation input from the operator via the operation display 60 and operation switches 70, and displays various information to the operator.

[0029] Figure 5 shows the details of the combination weighing control unit 51. The combination weighing control unit 51 has functional units such as a combination calculation unit 51a, a selection hopper opening / closing command unit 51b, a total discharge processing command unit 51c, and a zero point adjustment processing command unit 51d.

[0030] The combination calculation unit 51a receives the weighing result signals output from the load cells 114b that measure the weight of each weighing hopper 114 via an amplifier, filter, etc. Then, it performs a combination calculation based on the weight (weighed value) of the items in each weighing hopper 114 and selects the weighing hopper 114 so that the total weight of the items falls within the allowable range. The selected hopper opening / closing command unit 51b sends an opening / closing command to the opening / closing gate 114a at the bottom of the weighing hopper 114 according to this selection result.

[0031] Furthermore, the total discharge processing command unit 51c and the zero point adjustment processing command unit 51d send an opening / closing command to the opening / closing gate 114a of the weighing hopper 114 when an operation input for these processing is made by the operator or when predetermined conditions are met.

[0032] (5) Operation of the combined weighing device and the bag-making and packaging device When goods are supplied from the supply conveyor device 101 of the preceding process to the combined weighing device 110, the goods are dispersed radially by vibration from the distribution feeder 111 and sent to the pool hopper 113 via the radial trough 112. After being temporarily pooled there, the goods are put into the weighing hopper 114, and the weight is measured by the load cell 114b of each weighing hopper 114. Then, from several weighing hoppers 114 selected by combination calculation based on these weighing results, the goods are dropped into the collective discharge chute 115, and these goods flow into the tube 122 of the bag-making and packaging device 120.

[0033] In the bag-making and packaging apparatus 120, a tubular film Fmc is formed around and below the tube 122 by the former 121 and tube 122, and is vertically sealed by the vertical sealing mechanism 123 (see Figure 3). When an item falls through the tube 122 onto this tubular film Fmc, a horizontal sealing mechanism 124 seals it horizontally, sewing the film together, and the center of the horizontally sealed portion is cut by the cutter of the horizontal sealing mechanism 124. In this way, bags B filled with items are produced one after another. These bags B are then transported to a weight checker 140 in the next process (see Figure 1).

[0034] (6) Details of the control of the combined weighing device and the bag-making and packaging device Next, we will explain some of the processes of the combined weighing device 110 and the bag-making and packaging device 120, referring to the control flow diagrams shown in Figures 6 to 9.

[0035] (6-1) Main flow Figure 6 shows the main control flow performed by the combination weighing control unit 51 of the combination weighing device 110. First, the combination weighing device 110 sets the operating environment, such as the weighing target value, upper and lower limits, and number of discharges, according to the items being handled (step S1). The operator selects an operating environment setting key from among the operating environment setting keys, drive unit power key, operation start key, all discharge key, zero point adjustment key, etc., displayed on the operation display 60 to make the settings.

[0036] After completing the settings in step S1, if the start operation key is pressed and the system is in a normal operation state, the combination weighing control unit 51 performs operation processing in step S6 (step S2). If the full discharge key is pressed or the combined failure cumulative value E (described later) exceeds a predetermined value Emax, the combination weighing control unit 51 performs full discharge processing in step S7 (step S3). If the zero point adjustment key 66 is pressed or the conditions for automatic zero point adjustment are met, the combination weighing control unit 51 performs zero point adjustment processing in step S8 (step S4). When the zero point adjustment processing is performed in step S8, if the correction flag described later is set to "Yes" for the load cell 114b corresponding to the weighing hopper 114 for which the zero point adjustment processing was performed, the combination weighing control unit 51 sets that correction flag to "No" (step S9). Also, if any other switch (key) is pressed, the combination weighing control unit 51 performs other processing in step S10 (step S5).

[0037] (6-2) Processing flow for normal operation Figure 7 shows the processing flow during normal operation. When a timing signal is received from the bag-making and packaging control unit 52 requesting the discharge of goods, the combination calculation unit 51a of the combination weighing control unit 51 acquires weighing result data from each load cell 114b and prepares weighing data (weighing values) for combination calculation (steps S11, S12). The process of preparing this weighing data will be described in detail later.

[0038] In step S13, the combination calculation unit 51a performs a combination calculation. If there is a combination in which the total weight of the items in a predetermined number (for example, 3) weighing hoppers 114 is within the allowable weight range, the combination is considered valid and the process proceeds to step S15 (step S14). In step S15, the cumulative value E for unsuccessful combinations, which will be described later, is reset to 0, and the three weighing hoppers 114 selected during the combination calculation are opened and closed. That is, the combination weighing control unit 51 sends a discharge command to one or more weighing hoppers 114 determined by the combination calculation. When the opening / closing gate 114a of the selected weighing hopper 114 opens, the items in the weighing hopper 114 fall through the collective discharge chute 115 and tube 122 into the cylindrical film Fmc. Then, in step S16, when the combined weighing control unit 51 sends a discharge completion signal to the bag-making and packaging control unit 52 of the bag-making and packaging device 120, the bag-making and packaging device 120 heat-seals the cylindrical film Fmc that is covering these articles using the lateral sealing mechanism 124.

[0039] In step S17, the pool hopper 113, located above the weighing hopper 114 from which the goods were discharged, is opened and closed, and new goods enter the weighing hopper 114. Also in step S17, the radial trough 112 is activated to supply new goods to the pool hopper 113.

[0040] If a combination is not formed in step S14, that is, if the total weight of the items does not fall within the acceptable range no matter how they are combined, the process proceeds to step S18. In step S18, 1 is added to the cumulative value of unsuccessful combinations E, which indicates the number of consecutive unsuccessful combinations. Based on the weighing results, the weighing hopper requiring additional supply is determined, and the process proceeds to step S17 to open and close the corresponding pool hopper 113. If a combination is formed next time, the cumulative value of unsuccessful combinations E is reset to 0 in step S15. However, if the supply operation by the distributed feeder 111, radial trough 112, and pool hopper 113 is repeated but sufficient items are not supplied to the weighing hopper 114, the cumulative value of unsuccessful combinations E will continue to increase. When this cumulative value of unsuccessful combinations E exceeds a predetermined value Emax, it is determined that the supply of items to the combination weighing device 110 has ceased and it is no longer possible to continue bagging items within the acceptable weight range, and the process automatically proceeds to the complete discharge process from step S3 to step S7 in Figure 6.

[0041] In step S11, if it is determined that there is no timing signal from the bag-making and packaging control unit 52, the combined weighing control unit 51 moves to step S19. In step S19, it is determined whether a predetermined time has elapsed since the timing signal disappeared. Specifically, in step S19, the combined weighing control unit 51 determines whether the accumulated time since the timing signal disappeared has exceeded a predetermined threshold time. If it is determined in step S19 that the predetermined time has elapsed, the combined weighing control unit 51 sets the correction flag to "Yes" (step S20) and moves to the abnormality monitoring process in step S21. The abnormality monitoring process will be described later. In step S19, if it is determined that the accumulated time has not exceeded the predetermined time, the process returns to step S11.

[0042] (6-3) Processing flow for all discharges The full discharge process in step S7 of Figure 6 is performed when the operator presses the full discharge key 65, or when the cumulative value of combination failures E exceeds a predetermined value Emax. In this full discharge process, the weighing hoppers 114 are forcibly opened three at a time in sequence, and all the items in the weighing hoppers 114 are discharged and packed into bags. This full discharge process is the same as the full discharge process disclosed in Patent Document 1 (Japanese Patent Application Publication No. 2001-2013).

[0043] (6-4) Zero-point adjustment process flow In the zero-point adjustment process (hereinafter referred to as the zero-point process) in step S8 of Figure 6, the items in the weighing hopper 114 selected by the operator are forcibly discharged, and the weight at that time is stored as the zero point with the weighing hopper 114 empty. When the combined weighing device 110 is used continuously, liquids such as seasonings in the case of potato chips, or juices in the case of prepared foods, adhere to the weighing hopper 114. This negatively affects weighing accuracy, so maintenance (cleaning) is necessary, but the zero-point process can suppress the effect of deposits accumulated on the inner surface of the weighing hopper 114.

[0044] Furthermore, the zeroing process in step S8 is performed periodically even during normal operation. For example, when the number of times goods are discharged from a weighing hopper 114 exceeds a threshold (an example of the conditions for automatic zeroing adjustment described above), zeroing is performed only for that weighing hopper 114. While this zeroing process is being performed, goods cannot be supplied to that weighing hopper 114, and the number of weighing hoppers 114 participating in the combination calculation decreases. However, unless zeroing is performed simultaneously on a large number of weighing hoppers 114, this does not significantly affect the success of the combination calculation.

[0045] (6-5) Figure 8 shows the processing flow for preparing the weighing data in step S12 of Figure 7. In step S31, the combined weighing control unit 51 acquires weighing values ​​from each load cell 114b as weighing data. Next, in step S32, the combined weighing control unit 51 checks whether a correction flag is present or not. If the correction flag was set to "present" in step S20, the process moves to step S33, where the combined weighing control unit 51 corrects the weighing data using the difference. This difference is the difference between the first weighing value acquired before the timing signal disappeared or before a predetermined time had elapsed after the timing signal disappeared, and the second weighing value acquired in step S31. For example, if the weighed value obtained from the first load cell 114b corresponding to the first weighing hopper 114 at a time close to the time when the cumulative time was set to zero is 10.17g, and the weighed value obtained in step S31 from the first load cell 114b corresponding to the first weighing hopper 114 is 9.82g, then the difference between them is 0.35g. Then, in step S33, the weighed data obtained in step S31 (9.82g) is corrected by the difference (0.35g).

[0046] In step S34, the combination weighing control unit 51 checks for the presence or absence of an abnormality flag. The abnormality flag is a flag set in step S46 of the abnormality monitoring process (see Figure 9) described later, and is set (set to "present") for load cells 114b with low reliability of weighing data. In step S34, if there are load cells 114b with the abnormality flag set to "present", it is decided that the weighing data obtained from those load cells 114b will be excluded from the combination calculation (step S35). The combination weighing control unit 51 does not use the weighing data that has been decided to be excluded from the combination calculation in step S34 in the combination calculation in step S13. For example, if there are 1st to 12th weighing hoppers 114, and it is decided not to use the weighing data obtained from the load cell 114b corresponding to the 12th weighing hopper 114, the combination weighing control unit 51 will only use the weighing data obtained from the remaining 1st to 11th weighing hoppers 114 (or the corrected data if correction is necessary) for the combination calculation.

[0047] (6-6) Figure 9 shows the processing flow for abnormality monitoring in step S21 of Figure 7. Abnormality monitoring is performed during periods when there is no timing signal from the bag-making and packaging control unit 52. Therefore, when it is determined in step S41 that there is a timing signal, the accumulated time is set to zero (step S42), and the process returns to normal operation as shown in Figure 7. When it is determined in step S41 that there is no timing signal, in step S43 the combined weighing control unit 51 determines whether the first time interval has elapsed, and if it has, it acquires weighing data from each load cell 114b (step S44). In other words, in the abnormality monitoring process, the combined weighing control unit 51 acquires weighing data from each load cell 114b at each first time interval.

[0048] The first time interval is naturally a shorter time interval than the predetermined time, and here it is set to a value in the numerical range of 1 second to several seconds, specifically 2 seconds. Here the first time interval is set to the initial value of 2 seconds, but as a method of setting the first time interval, if the standard time interval of the timing signal from the bag-making and packaging control unit 52 during normal operation is 1.5 seconds, then it is also possible to set the first time interval to twice that, 3.0 seconds.

[0049] On the other hand, the predetermined time used in step S19 above is set to a value in the range of 1 minute to several minutes, specifically 5 minutes.

[0050] The combined weighing control unit 51, which has acquired weighing data from each load cell 114b, determines in step S45 whether the rate of change of the weighing data is greater than a threshold. If the rate of change of the weighing data is large, it determines that an abnormality has occurred in the weighing hopper 114 corresponding to that load cell 114b, and sets the abnormality flag corresponding to that weighing hopper 114 and load cell 114b to "Yes" (step S46).

[0051] (7) Characteristics of combination weighing devices (7-1) In the combined weighing device 110 according to this embodiment, in step S19, it is determined whether a predetermined time has elapsed since the timing signal from the bag-making and packaging control unit 52 disappeared. If it is determined in step S19 that the predetermined time has elapsed (the accumulated time has exceeded the predetermined time), the combined weighing control unit 51 sets the correction flag to "yes". As a result, the combined weighing control unit 51 moves from step S32 to step S33 in the weighing data preparation process and performs correction of the weighing data using the difference prior to the combination calculation in step S13. In normal operation, the combined weighing control unit 51 does not send an instruction to the weighing hopper 114 to discharge items when there is no timing signal. In other words, in the combined weighing device 110, if the combined weighing control unit 51 does not send a discharge instruction to the target weighing hopper 114 for a predetermined period of time, the weighing data of the load cell 114b will be corrected using the difference until zeroing (step S8) is performed and the correction flag is set to "no" (step S33).

[0052] When the timing signal from the bag-making and packaging control unit 52 is lost, the combined weighing control unit 51 stops sending discharge commands to the opening and closing gates 114a of all weighing hoppers 114. If the combined weighing control unit 51 continues not to send discharge commands to the weighing hoppers 114 for a predetermined period of time, the reliability of the weighing data (weighing value) decreases due to temperature changes in the space surrounding the load cell 114b, such as a decrease in heat generated from the motor that drives the opening and closing gates 114a of the weighing hoppers 114. In light of this, when operation is restarted after the weighing hoppers 114 have not been opened or closed for longer than a predetermined period of time, that is, when a timing signal from the bag-making and packaging control unit 52 is received and the combined calculation is restarted, the combined weighing control unit 51 corrects the weighing data using the difference (step S33) until zeroing (step S8) is performed and the correction flag is set to "none" during the weighing data preparation process (see step S12 and Figure 8). This reduces, to some extent, the degradation in the reliability of the measurement data that occurred during the specified period, allowing for combination calculations using measurement data with a certain degree of reliability to be performed when operations are resumed.

[0053] (7-2) In the combined weighing device 110, as shown in steps S43 and S44 of Figure 9, weighing data is periodically acquired from each load cell 114b while there is no timing signal from the bag-making and packaging control unit 52 (referred to here as the first state) for a predetermined period of time. During the first state, weighing data is acquired from each load cell 114b at first time intervals (here, 2 seconds), and in steps S45 and S46, an abnormality in the weighing hopper 114 is determined, and if an abnormality is found, the abnormality flag is set to "Yes". Furthermore, the weighing values ​​from the load cells 114b corresponding to the weighing hopper 114 with the abnormality flag set to "Yes" are excluded from the multiple weighing values ​​used in the combined calculation after operation is resumed (step S35). As a result, the accuracy of the combined calculation results is improved in the combined weighing device 110.

[0054] Possible causes of the malfunction include something entering the weighing hopper 114 from the outside during the specified time period, or an item that was caught in the upper pool hopper 113 falling into the weighing hopper 114 during the specified time period. Therefore, it is preferable to keep the malfunction flag, once set to "present," in the "present" state until the operator checks the weighing hopper 114 during maintenance and the item causing the malfunction is removed from the weighing hopper 114.

[0055] (7-3) In the combined weighing device 110, the zeroing process in step S8 is performed periodically during normal operation. Then, in step S19, if it is determined that a predetermined time has elapsed, the correction flag is set to "yes" in step S20. Therefore, when normal operation is resumed after receiving a timing signal from the bag-making and packaging control unit 52, the zeroing process is performed sequentially in each weighing hopper 114. In other words, of the first load cell 114b corresponding to the first weighing hopper 114 that discharged goods after the resumption of normal operation, and the second load cell 114b corresponding to the second weighing hopper 114 that discharged goods after the resumption of operation, the first load cell 114b will undergo zeroing, while the second load cell 114b will not. In step S9, the correction flag for the first load cell 114b, which underwent zeroing, returns to "no," but the correction flag for the second load cell 114b, which did not undergo zeroing, remains "yes." Then, the combination weighing control unit 51 continues to make corrections in the combination calculation based on the difference in the weighing values ​​acquired by the second load cell 114b.

[0056] Thus, in the combination weighing device 110, zeroing is not performed on the second load cell 114b corresponding to the second weighing hopper 114 from which the goods were discharged after the resumption of normal operation. Therefore, the reliability of the next weighing value for the second load cell 114b is low. In light of this, the combination weighing control unit 51 continues to correct the combination calculation using the difference in weighing values ​​acquired by the second load cell 114b, thereby maintaining the accuracy of the combination calculation.

[0057] On the other hand, in the combined weighing device 110, after normal operation resumes, not all load cells 114b corresponding to the weighing hopper 114 from which the goods were discharged are immediately zeroed. Therefore, even in the period immediately following the resumption of normal operation, a large number of weighing hoppers 114 (weighing values ​​output by load cells 114b) can be secured to participate in the combined calculation.

[0058] (8) Variations (8-1) In the above embodiment, the present invention was explained using the example of a state in which the combined weighing control unit 51 does not send a discharge instruction to the target weighing hopper 114, and there is no timing signal from the bag-making and packaging control unit 52. However, the present invention (correction by difference) may be applied in other states as well.

[0059] For example, the present invention may be applied when the supply of goods from the supply conveyor device 101, which is another device upstream of the combination weighing device 110, has stopped. Alternatively, the present invention may be applied when the combination weighing device 110 has stopped normal operation due to manual operation by an operator. The state in which the supply of goods from the supply conveyor device 101 has stopped can be determined from the weight monitoring results of the goods on the distributed feeder 111, and the stoppage of the combination weighing device 110 can be determined from the operator's input.

[0060] (8-2) In the above embodiment, after resuming normal operation, not all load cells 114b corresponding to the weighing hopper 114 that discharged the goods are immediately zeroed. Even with this control, the accuracy of the combination calculation is maintained to some extent by correction based on the difference in weighing values, but it is also possible to control the system to perform zeroing on all load cells 114b as quickly as possible. For example, as a condition for zeroing in step S4, if the correction flag is "present" and the weighing hopper 114 has discharged goods once after resuming normal operation, the corresponding load cell 114b may be immediately zeroed. If this condition is adopted, the number of weighing hoppers 114 and load cells 114b that can participate in the combination calculation will be small for a while after resuming normal operation, but zeroing on all load cells 114b will be completed early, and the correction flag will return to "absent" for all load cells 114b early after step S9. This has the disadvantage that, for a while after normal operation resumes, there will be more load cells 114b that are subject to zeroing, but it has the advantage of ending the process of correcting the measured values ​​based on the difference and performing combination calculations sooner.

[0061] (8-3) In the above embodiment, the difference between the first measured value acquired before the timing signal disappears or before a predetermined time has elapsed after the timing signal disappears and the second measured value acquired in step S31 is calculated, and the second measured value is corrected based on that difference. That is, whether the difference is a positive or negative number, the second measured value is corrected based on that difference.

[0062] Alternatively, considering that excessive correction could inaccurately inflate the total weight value of the combined weighing results, it is also possible to adopt a control system that only applies correction when the difference is a positive number, and does not apply correction when the difference is a negative number.

[0063] (8-4) In the above embodiment, the difference between the first measured value acquired before the timing signal disappears or before a predetermined time has elapsed after the timing signal disappears and the second measured value acquired in step S31 is calculated, and the second measured value is corrected based on this difference. There are several candidates that can be adopted as the first measured value. The measured value 1A of load cell 114b immediately before the timing signal disappears may be adopted, the measured value 1B of load cell 114b immediately after the timing signal disappears may be adopted, or the maximum value 1C or average value 1D of the measured values ​​of multiple load cells 114b acquired at first time intervals (2 seconds) from the time the timing signal disappears until normal operation resumes may be adopted. Alternatively, an appropriate first measured value may be calculated from these measured values ​​1A, 1B, maximum value 1C, and average value 1D.

[0064] (8-5) In the above embodiment, after the correction flag is set to "Yes" in step S20, when normal operation is resumed after receiving a timing signal from the bag-making and packaging control unit 52, zeroing is performed sequentially in each weighing hopper 114. The timing of the zeroing is not related to the difference value or the time until operation resumes (the accumulated time reset in step S42).

[0065] Alternatively, the timing of zeroing after normal operation resumes may be changed depending on the magnitude of the difference. If the difference is large and the amount of correction is large, the timing of zeroing can be advanced, and if the difference is small and the amount of correction is small, the timing of zeroing can be kept as normal, thus balancing the decrease in operating rate with the accuracy of combinatorial calculations.

[0066] Furthermore, the timing of zeroing after normal operation resumes may be changed depending on the time until operation resumes. For example, if the time until operation resumes is 10 minutes or less, the timing of zeroing should be the same as usual, but if the time until operation resumes exceeds 10 minutes, the timing may be advanced so that zeroing is performed earlier than usual in the load cells 114b of each weighing hopper 114.

[0067] (8-6) In the above embodiment, the weighing value from the load cell 114b corresponding to the weighing hopper 114 with the abnormality flag set to "present" is excluded from the multiple weighing values ​​used in the combination calculation after the restart of operation (step S35). This is a preferred approach in a production line where the cause of the abnormality is expected to be the intrusion of foreign matter into the weighing hopper 114 from the outside during a predetermined period of time.

[0068] However, if there is little risk of foreign matter contamination in the weighing hopper 114 and priority is to not reduce the number of weighed values ​​participating in the combination calculation, it is preferable to take one of the following two alternative approaches.

[0069] The first approach involves allowing the weighing values ​​from the load cell 114b corresponding to the weighing hopper 114 with the abnormal flag set to "Yes" to participate in the combination calculation without applying differential correction after operation resumes. This is because, if a worker on the production line returns items from some of the weighing hoppers 114 to the distribution feeder 111 in order to wipe off dirt from them within a predetermined time, differential correction may be inappropriate. However, since this is not an abnormality such as foreign matter contamination, the benefits of including the weighing values ​​corresponding to those weighing hoppers 114 in the combination calculation may outweigh the drawbacks. For example, comparing the deterioration in combination calculation accuracy due to X weighing hoppers out of 10 not participating in the combination calculation with the deterioration in combination calculation accuracy due to the lack of correction applied to the weighing values ​​of those X weighing hoppers, if the former deterioration is more unacceptable, then this first approach is preferable.

[0070] The second approach involves correcting the measured value from the load cell 114b corresponding to the weighing hopper 114 with the abnormal flag set to "present" after operation has resumed, based on the average value of the differences corresponding to other weighing hoppers 114 with the abnormal flag set to "absent". If this approach is adopted, and the device configuration (arrangement of hoppers and motors) is such that the differences corresponding to other weighing hoppers 114 experiencing similar ambient temperature changes are considered highly reliable, the measured value from the load cell 114b corresponding to the weighing hopper 114 with the abnormal flag set to "present" will also be appropriately corrected by the alternative value. [Explanation of Symbols]

[0071] 51 Combination weighing control unit (control unit) 110 Combination weighing device 114 Measuring hopper (hopper) 114b Load cell (weighing section) [Prior art documents] [Patent Documents]

[0072] [Patent Document 1] Japanese Patent Publication No. 2001-2013

Claims

1. Multiple hoppers that store the input items and discharge the items according to a discharge instruction, Multiple weighing units are provided corresponding to each of the multiple hoppers, and acquire the mass of the articles stored in the hoppers as a measured value. A control unit that performs a combination calculation using multiple measured values ​​and sends the discharge instruction to one or more hoppers determined by the combination calculation, Equipped with, When the control unit restarts operation after a predetermined period of time during the first state in which it does not send the discharge instruction to the hopper, it corrects the second measured value based on the difference between the first measured value acquired by the measuring unit before the restart of operation and the second measured value acquired by the measuring unit after the restart of operation, and performs the combination calculation until zeroing is performed in the measuring unit corresponding to the hopper. Combination weighing device.

2. The control unit, While the first state continues for the predetermined time, the measured value is received from the measuring unit at the first time interval. Based on the measured value received from the measuring unit, the presence or absence of an abnormality in the hopper is determined. The combination weighing apparatus according to claim 1.

3. If the control unit determines that there is an abnormality in the hopper, it removes the measurement value obtained by the measurement unit corresponding to the hopper that was determined to have an abnormality from the plurality of measurement values ​​used in the combination calculation after the restart of the operation. The combination weighing apparatus according to claim 2.

4. The control unit, After the restart of the operation, the first weighing unit corresponding to the first hopper from which the article was discharged and the second weighing unit corresponding to the second hopper from which the article was discharged are configured such that the first weighing unit performs the zeroing process, while the second weighing unit does not perform the zeroing process. In the above combination calculation, the correction based on the difference of the measured values ​​acquired by the second measuring unit is continued. A combination weighing device according to any one of claims 1 to 3.

5. The control unit, after the restart of the operation, causes the weighing unit corresponding to all of the hoppers from which the articles were discharged to perform the zeroing process. A combination weighing device according to any one of claims 1 to 3.

6. If the control unit determines that there is an abnormality in the hopper, after the operation is resumed, it will determine the second measurement value corresponding to the hopper that was determined to have an abnormality. No correction is made based on the aforementioned difference. or, A correction is performed based on the difference corresponding to the other hoppers that were determined to be free of the aforementioned abnormality. The combination weighing apparatus according to claim 2.

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