metering filling method

Abstract

To solve the problem that correction of an error corresponding to drop of a packaged object filled by a filling device increases manufacturing cost because two measuring devices are needed for the correction in a conventional measuring filling method.SOLUTION: A measuring filling method of a measuring filling device comprising first and second filling machines 16, 19 and a measuring device 17 configured to measurement with a bag X filled with a packaged object Y alternately held, includes: performing a normal operation mode for performing a filling operation repeating the operation a plurality of times without performing calibration of an error of filling weight of the packaged object Y by measuring using the measuring device 17, and a measurement stabilizing mode for performing calibration of the error of the filling weight of the first and second filling machines between the normal operation modes under a predetermined condition; and, when the predetermined condition is established during the normal operation mode is continuously operated, changing the number of pulse controlling the filling machine in order to perform calibration of the filling weight of the first and second filling machines 16, 19 by operating the measurement stabilizing mode.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a weighing and filling method for filling a bag with an item to be packaged while weighing it. [Background technology]

[0002] Weighing and filling devices that weigh and fill bags with packaged materials, such as granules or powders. Using such weighing and filling devices, a packaging machine grips both upper sides of the bag with a pair of grippers and intermittently transports the bag (hereinafter referred to as "intermittent movement") while weighing and filling the packaged materials. In a weighing and filling method using such weighing and filling devices, a first filler with a large filling capacity first fills the packaged materials to a fill weight slightly less than the target fill weight (rough filling). Then, a second filler with a small filling capacity fills the packaged materials little by little to achieve an accurate set weight (corrective filling). Auger fillers are typically used as the first and second fillers. These auger fillers have the advantage of being able to pulse-control the auger's rotation speed and velocity, allowing the fill volume to be controlled by a pulse signal. This weighing and filling method allows the packaged materials to be filled quickly and relatively accurately compared to a single filler that weighs and fills at the same time.

[0003] As an example of the above-mentioned weighing and filling method, Patent Document 1 discloses a method in which a bag is gripped by a pair of intermittently moving grippers, and a first filling machine roughly fills the bag with the contents to be packaged; the bag is then intermittently moved to a second filling section, and the bag is then transferred to a gripping section provided on a weighing device, and the second filling machine weighs the contents to be packaged while correctively filling them, and then the bag is sealed.

[0004] Incidentally, for packaging materials such as flour and starch that do not require highly accurate weighing and filling, the weighing and filling method comprising rough filling and corrective filling disclosed in Patent Document 1 is sufficient. However, when weighing and filling packaging materials that require greater accuracy, such as expensive packaging materials, auger filling machines have disadvantages. That is, as described above, the second auger filling machine corrects the filling of a specified weight of packaging materials by pulse-controlling the auger rotation number and rotation speed, but an error occurs in the falling packaging materials when filling is completed by the auger filling machine (hereinafter referred to as "drop error").

[0005] FIG. 4 is an explanatory diagram for explaining this drop error, and illustrates the state immediately after bag X is transferred to the weighing device 31 (only the gripping portion is shown) and filled by the second filling machine 30. The auger of the second filling machine 30 stops when a signal is output from the weighing device 31 indicating that the target set weight has been reached. However, the packaged item Y detected by the filling machine 31 as the filling weight is limited to the item that has fallen into the bag X, and the drop difference Ya during the fall is not detected. Because the drop difference Ya occurs after the weighing device 31 detects that the set weight has been reached, the drop difference Ya is heavier than the target set weight, and the filling weight is inaccurate by that amount. If the height of the filling machine 30 is different or the type of bag X is different, this may affect the final target filling weight.

[0006] As a method for addressing this issue, as shown simply in Fig. 5, not only is a weighing device (first weighing device) 53 (only the gripping portion is shown) located at a position corresponding to the second filling machine 52, but also a weighing device (second weighing device) 54 is provided at a position downstream of this. When the first weighing device 53 detects that a preset weight has been reached, the filling operation of the second filling machine 52 is stopped and it is moved intermittently downstream, after which the second weighing device 54 measures the final weight of the final packaged item Y. In Fig. 5, X denotes bags, Y denotes packaged items, 50 denotes a gripper of the packaging machine, and 51 denotes the first filling machine. Patent Document 2 discloses a system (weighing and filling device) in which a weight checker is incorporated into a belt conveyor located downstream of the second filling machine and the first weighing device for weighing.

[0007] According to the above-mentioned weighing and filling method, the weight of the packaged item when the filling operation of the second filling machine 52 stops (the weight detected by the first weighing device 53) can be subtracted from the weight detected by the second weighing device 54 to calculate the weight of the drop difference Ya while it is falling from the second filling machine 52 toward the bag X.Therefore, by feedback-controlling the filling amount of the second filling machine 52 by this drop difference Ya, it is possible to approach the target filling weight and improve accuracy.

[0008] According to the above-mentioned weighing and filling method, the second weighing device 54, which weighs the final filling weight of the packaged item, is located in a section separate from the section of the second filling machine 52, which has the advantage that the weighing time of the first weighing device 53 can be kept short and the overall time for intermittent movement of the packaging machine can be shortened, thereby improving the processing capacity of the packaging machine. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Publication No. 62-52001 [Patent Document 2] Japanese Patent Application Publication No. 11-314602 Summary of the Invention [Problem to be solved by the invention]

[0010] However, the weighing and filling method as shown in Figure 5 requires a second weighing device 54 in addition to the first weighing device 53, which raises the problem of increased manufacturing costs. Also, the weighing system incorporating a weight checker as in Patent Document 2 results in a higher number of defective products and an increase in the amount of packaged goods discarded due to weighing errors.

[0011] In response to these problems, the present invention aims to provide a weighing and filling method that can minimize the reduction in the processing capacity of the intermittent movement of the packaging machine, while suppressing increases in manufacturing costs and reducing the amount of packaged material that is discarded due to weighing errors. [Means for solving the problem]

[0012] The measuring and filling method of the present invention is a measuring and filling method for a measuring and filling device comprising a first pulse-controlled filling machine that fills large volumes of powder or granular material into bags, a second pulse-controlled filling machine that fills small volumes and is located downstream of the first filling machine, and a weighing device that is installed together with the second filling machine and transfers bags filled with the packaged material to be weighed, and includes a normal operation mode in which the filling weight of the packaged material filled by the first and second filling machines is measured by the weighing device and the filling operation is repeated multiple times without correcting errors in the filling weight of the packaged material, and a mode in which the normal operation mode is performed under predetermined conditions. During the normal operation mode, a weighing stabilization mode is implemented in which errors in the filling weights of the first and second filling machines are calibrated. In the weighing stabilization mode, the first filling machine roughly fills a predetermined amount of packaged material without weighing the packaged material, and the second filling machine transfers the bag to a weighing device, first measuring the rough filling weight of the packaged material roughly filled by the first filling machine, and then measuring the packaged material with the weighing device while filling it from the second filling machine, stopping the filling of the packaged material when the packaged material reaches the target filling weight, and then measuring the final weight of the packaged material after filling has stopped with the weighing device. and determining whether the rough filling weight is within the threshold of the first filling target of the first filling machine, and if it is within the threshold, maintaining the previous filling amount of the first filling machine, and if it is outside the threshold, correcting the number of pulses of the first filling machine to calibrate the rough filling weight, subtracting the target set weight from the final weight to obtain the drop difference weight of the packaged item being filled into the bag from the second filling machine, and further dividing the calculated filling weight obtained by subtracting the drop difference weight and rough filling weight from the final weight by the total number of pulses input to the second filling machine to calculate the one-pulse filling weight of the second filling machine, and correcting the number of pulses equivalent to the drop difference weight from the total number of pulses input to the second filling machine to calibrate the total number of pulses input to the second filling machine. It is characterized by: [Effects of the Invention]

[0013] According to the measuring and filling method of the present invention, by operating the measuring stabilization mode only when predetermined conditions are met, the measuring device can accurately measure the fill weight, thereby minimizing the decrease in measuring accuracy. Moreover, since only one measuring device is required, increases in manufacturing costs can be suppressed. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a plan view showing a rotary packaging machine for carrying out the measuring and filling method of the present invention; [Figure 2] FIG. 1 is an explanatory diagram for simply explaining the measuring and filling method of the present invention. [Figure 3] Illustrative diagram of the measuring and filling method of the present invention. [Figure 4] An explanatory diagram for explaining the problems of the conventional measuring and filling method [Figure 5] An explanatory diagram showing a conventional measuring and filling method in a simplified manner. DETAILED DESCRIPTION OF THE INVENTION

[0015] An embodiment of the measuring and filling method of the present invention will be described below, but before that, a rotary packaging machine, which is an example of a packaging device for carrying out the present invention, will be briefly described.

[0016] Reference numeral 1 in Fig. 1 denotes a rotary packaging machine that continuously fills a bag X with a predetermined weight of packaged material Y, such as powder or granular material, and packages the packaged material. This rotary packaging machine 1 is mounted on a base 4, and is equipped with an output conveyor 2 on the periphery that conveys bag boxes 13 and packaged bags X downstream, as well as a control device (not shown) that controls the entire packaging apparatus including the rotary packaging machine 1. Note that the measuring and filling method of the present invention can be carried out not only with this rotary packaging machine 1, but also with a linear packaging machine or an oval packaging machine.

[0017] In the rotary packaging machine 1, eight pairs of grippers 3 (only the gripping portions of the grippers 3 are shown in FIG. 2) are attached to the periphery of a circular rotor 11. The rotational driving force of a drive motor arranged in a base 4 below the circular rotor 11 is transmitted to the circular rotor 11, causing the circular rotor 11 to rotate intermittently in a clockwise direction (rotation direction R) at a pitch of 45° around the circumference.

[0018] The circular rotor 11 is divided into the following sections, and the following packaging operations are performed in each section. (1) A bag supply section in which empty bags X are supplied from a bag box 13 by a bag supply mechanism 12 (2) A printing and bag opening section in which the printing device 14 prints the expiration date and the like on the bag X and the bag opening mechanism 23 opens the bag X. (3) A first filling section equipped with a large-capacity hopper 15, which roughly fills a large amount of packaged goods Y into bags X at high speed (faster than the second filling machine 19 described later). (4) A second filling section in which a weighing device 17 is provided, and in which the bag X filled with the packaged item Y by the first filling machine 16 is transferred from the gripper 3, and a small volume of the packaged item Y is filled at a low speed and accurately by the second filling machine 19 from the small volume hopper 18. (5) A tapping section in which the bottom of the bag X is tapped by a vibration plate 24 to drop the packaged item Y into the bag. (6) A degassing section in which the air in the bag X is removed by the degassing device 20. (7) A sealing section that seals the opening of the bag X using a sealing device 21 (8) A cooling and carrying-out section in which the sealed portion of the bag X is cooled by a seal cooling device 22 and the packaged bag X is carried out of the system from the circular rotor 11 by a carrying-out conveyor 2.

[0019] Of the above sections, the bag supply section (1), printing / bag opening section (2), tapping section (5), degassing section (6), sealing section (7), and cooling / discharge section (8) are the same as those in the prior art, so detailed explanations will be omitted. The first filling section (3) and the second filling section (4), which are characteristic of the present invention, will be explained in detail below.

[0020] The first filling section (3) is equipped with a first filling machine 16 equipped with a large-capacity hopper 15, which roughly fills a large volume of packaged item Y into bags X at high speed. This first filling machine 16 uses a conventionally known auger filling machine. The first filling machine 16 drives the filling auger (screw) with a servomotor, and the rotation speed and number of revolutions of this servomotor are controlled by pulse signals from a control device. The first filling machine 16 controls the servomotor so that the filling amount (within a threshold value of the "first filling target") is less than the target filling weight (hereinafter referred to as the "target filling weight") that the packaged item Y must ultimately be filled into the bags X. If the packaged item Y is overfilled in this first filling section (3) beyond the target filling weight, there is no mechanism for removing the packaged item in a subsequent section, and the overweight bags X would have to be discharged from the system as defective products. Therefore, the filling amount is set to always be less than the target filling weight.

[0021] In the first filling section (3), there is no weighing device 17 like in the second filling section (4), and the packaged item Y is filled from the first filling machine 16 without being weighed. For this reason, in the normal operation mode described below, a signal of the previously set number of pulses is continuously output from the control device to the first filling machine 16. When the mode is switched to the weighing stabilization mode during calibration of the first and second filling machines 16, 19 to correct errors, the number of pulses from the control device is controlled so that the filling weight by the first filling machine 16 is within the threshold value of the first filling target.

[0022] Regarding the setting of the threshold value of the first filling target, if the target filling weight is assumed to be 112 g, the amount of packaged item Y filled by the first filling machine 16 is set to 105 g, which is less than the target filling weight of 112 g. Furthermore, the threshold value of this first filling target is set, for example, within a range of ±1.5 g, so that the range of 103.5 g to 106.5 g is the threshold value. Note that this threshold value is set with safety in mind to prevent overfilling of packaged item Y, and therefore may be set within an accuracy range that does not interfere with filling by the first filling machine 16, which will be described later.

[0023] The second filling section (4) is equipped with a small-volume hopper 18 and is equipped with a second filling machine 19 that fills a small volume of packaged goods Y at a low speed with high accuracy. This second filling machine 19 is also a conventionally known auger filling machine, but is smaller than the first filling machine 16. The second filling machine 19 also drives the filling auger (screw) with a servo motor, and the number of rotations and rotation speed of this servo motor are controlled by pulse signals from a control device.

[0024] A weighing device 17 is installed in the second filling section (4). This weighing device 17 uses a device such as a load cell and is equipped with a weighing gripper 17a that transfers the bag X held by the gripper 3 of the rotary packaging machine 1 to the weighing device 17 side. In the normal operation mode, the bag X filled with the item Y to be packaged in the first filling section (3) is gripped by the gripper 17a, and the item Y is filled from the second filling machine 19 until the target filling weight is reached. In the weighing stabilization mode, first, the bag X filled with the item Y to be packaged in the first filling section (3) is gripped by the gripper 17a and the filling amount of the item Y to be packaged in the first filling section (3) is measured, and then, while continuing to measure with the weighing device 17, the bag X is filled with the item Y to be packaged from the second filling machine 19 until the target filling weight is reached. Furthermore, when the target filling weight is reached, the filling of the packaged item Y is stopped and the final weight of the bag X is measured.

[0025] Next, we will explain two modes for filling the packaged item Y in the first filling section (3) and the second filling section (4). These two modes include the normal operation mode and the weighing stabilization mode as described below.

[0026] (Normal operation mode) In the normal operation mode, when the first filling machine 16 fills the packaged item Y in the first filling section (3), a predetermined number of pulses is input from the control device to the first filling machine 16. The predetermined number of pulses is the number of pulses from the calibration data output to the first filling machine 16 when a calibration, which will be described later, is performed when the rotary packaging machine 1 is started. When the filling operation is ongoing, the number of pulses from the previous calibration is input as is, and the same number of pulses as the previous time are output from the control device to the first filling machine 16, and filling of the packaged item Y continues.

[0027] Furthermore, in the normal operation mode, the drop error of the packaged item Y is not calibrated for the second filling machine 30, as explained using Figure 4. In this normal operation mode, since such calibration is not performed for the first filling machine 16 and the second filling machine 19, the filling operation of the packaged item Y is quicker, but there is a risk of an error in the drop difference Ya occurring. However, this error can be minimized by periodically performing the weighing stabilization mode described below.

[0028] (Metering stabilization mode) (Metering stabilization mode in the first filling section) During the periodically performed weighing stabilization mode, if the filling weight of the packaged item Y in the first filling section (3) deviates from the first filling target threshold, the number of pulses from the control device is corrected so that the auger rotation speed of the first filling machine 16 becomes a corresponding value. Specifically, before filling the package Y from the second filling machine in the second filling section (4), the filling weight of the packaged item Y filled in the first filling section (3) is measured. The average value of this filling weight for the most recent predetermined number of times (e.g., three times) is calculated, and this average measured weight is divided by the total number of pulses of the first filling machine 16 to calculate the filling weight per pulse (g / pulse). Using this new filling weight per pulse (g / pulse), the number of pulses of the first filling machine 16 is increased or decreased to correct the filling weight so that the filling weight of the first filling machine 16 falls within the threshold.

[0029] To explain this using a specific example, the final target filling weight is 112g, the first filling target is 105, and the threshold value is in the range of ±1.5g (103.5g to 106.5g). If the most recent weighed weights in the weighing stabilization mode are 105.05g, 105.58g, and 105.28g, the average of the most recent three weighings by the first filling machine 16 is 105.30g. If the total number of pulses for each of the most recent three weighings is 9,130 ​​pulses, the fill weight of packaged item Y per pulse (g / pulse) is 0.0115g. In this example, the most recent average value of the first filling machine 16 is 105.30 g, which is within the threshold, so no correction is necessary. However, if it falls outside the threshold, the number of pulses is increased or decreased using the new filling weight of packaged item Y per pulse of 0.0115 g so that the filling weight of the first filling machine 16 falls within the threshold.

[0030] (Metering stabilization mode in the second filling section) As described above, in the second filling section (4), the second filling machine 19 fills the packaged item Y while weighing it with the weighing device 17, and the second filling machine 19 stops filling the packaged item Y the moment the weighing device 17 detects the target filling weight of the packaged item Y. However, if the second filling machine 19 stops filling the packaged item Y the moment the target filling weight is detected, as shown in Figure 4, the second filling machine 30 will fill the bag X with an excess amount of the drop Ya during filling, resulting in a drop error. In the weighing stabilization mode, in order to calibrate this drop error, the second filling section (4) performs calibration in the following steps (see Figure 3).

[0031] (Step 1) When the bag X is moved to the second filling section (4) and intermittently stopped, the bag X is gripped by the gripping part 17a provided on the weighing device 17, the gripper 3 is released, and the weight of the packaged item Y that was loosely filled in the first section (3) is measured (Figure 3-1). The weight of the packaged item Y at this time is defined as the "loosely filled weight (A)." Therefore, at this point, the second filling machine 19 has not yet filled the packaged item Y.

[0032] (Step 2) After the rough filling weight (A) is measured, correction filling is started by the second filling machine 19 (Figure 3-2). This correction filling fills the packaged item Y little by little to reach the target set weight (B) (the target set weight (B) is set to be the same as the target filling weight), and the auger of the second filling machine 19 is stopped the moment the weighed value of the weighing device 17 reaches the target set weight (B). Therefore, the weight of the drop difference Ya (drop difference weight (C)) is not included in the target set weight (B).

[0033] (Step 3) After filling by the second filling machine 19 stops, the weighing device 17 measures the final weight of the bag X (Figure 3-3). This final weight (D) is the sum of the target set weight (B) and the drop difference weight (C) (target set weight (B) + drop difference weight (C)).

[0034] (Step 4) In the fourth step, the fill weight (g / pulse) (1-pulse fill weight (E)) of the packaged item Y per pulse of the second filling machine 19 is calculated. The 1-pulse fill weight of the second filling machine 19 is calculated by subtracting the rough fill weight (A) and the drop difference weight (C) from the final weight (D) to obtain a calculated fill weight (F), which is then divided by the total number of pulses input into the second filling machine 19 (calculated fill weight (F) / total number of pulses).

[0035] (Step 5) As described above, the second filling machine 19 fills the bag X with more packaged goods Y by the drop difference Ya during filling, resulting in a drop error. Therefore, in step 5, the number of pulses input to the second filling machine 19 is calibrated based on the one-pulse filling weight (E) calculated above. Because the target set weight (B) is set to be the same as the target filling weight, the actual final weight (D) is greater than the target filling weight by the drop difference weight (C). Therefore, in the subsequent normal operation mode, the total number of pulses of the second filling machine 19 is corrected to be less by the drop difference weight (C), and the number of pulses of the second filling machine 19 is calibrated so that the final weight (D) approaches the target filling weight between normal operation modes.

[0036] As described above, in the weighing stabilization mode of the second filling section (4), after calibrating the number of pulses input to the second filling machine 19, the system returns to the normal operation mode and repeats the normal operation mode a predetermined number of times until the next weighing stabilization mode is entered. The condition for switching from the normal operation mode to the weighing stabilization mode may be that the normal operation mode has been executed for a predetermined operating time (e.g., every hour) or a predetermined number of times (e.g., when it has been executed 1,000 times). Furthermore, since fluctuations in the weight of the packaged item Y are often due to environmental changes such as temperature and humidity, the weighing stabilization mode may be executed when the environment changes (in this case, the temperature and humidity are measured periodically). Furthermore, the weighing stabilization mode may also be executed when the type or lot of the packaged item changes. Furthermore, when starting the rotary packaging machine, the weighing stabilization mode may first be executed, then switched to the normal operation mode, and the weighing stabilization mode may be executed periodically.

[0037] As described above, by periodically performing the weighing stabilization mode, accurate filling is possible with one weighing device 17, minimizing filling errors. Moreover, since it is only necessary to place one weighing device 17 corresponding to the second filling position, increases in manufacturing costs can be suppressed. Furthermore, compared to systems that incorporate a weight checker for weighing, the number of defective products is significantly reduced, and the amount of packaged goods discarded due to weighing errors can be reduced. [Industrial Applicability]

[0038] The present invention is useful in a measuring and filling method for various packaging machines that measures the contents to be packaged while filling them into bags. [Explanation of symbols]

[0039] 1. Rotary wrapping machine 2. Discharge conveyor 3 Grippers 11 Circular rotor 12 Bag feeding mechanism 13 bag box 14 Printing device 15 Large capacity hopper 16 First Filling Machine 17 Weighing device 17a Grip 18 Small Capacity Hopper 19 Second filling machine 20 Degassing device 21 Sealing device 22 Seal cooling device 23 Bag opening mechanism 24 Diaphragm Y Packaged item X bag

Claims

1. A measuring and filling method for a measuring and filling device comprising a pulse-controlled first filling machine that fills a large amount of powder or granular material into bags, a pulse-controlled second filling machine that fills a small amount and is located downstream of the first filling machine, and a weighing device that is installed together with the second filling machine and transfers bags filled with the packaged material to be weighed, comprising: a normal operation mode in which the filling weight of the packaged items filled by the first and second filling machines is measured by a weighing device and the filling operation is repeated multiple times without correcting for errors in the filling weight of the packaged items; and a weighing stabilization mode in which, under predetermined conditions, errors in the filling weight of the first and second filling machines are corrected between normal operation modes; In the weighing stabilization mode, the first filling machine loosely fills a predetermined amount of packaging material without weighing the packaging material, In the second filling machine, the bag is transferred to a weighing device, and the rough filling weight of the packaged items roughly filled by the first filling machine is first measured, and then the packaged items are filled from the second filling machine while being weighed by the weighing device. When the target filling weight of the packaged items has been filled, the filling of the packaged items is stopped, and the final weight of the packaged items after filling has stopped is measured by the weighing device. Determine whether the rough filling weight is within a threshold value of a first filling target of the first filling machine, and if it is within the threshold value, maintain the previous filling amount of the first filling machine, and if it is outside the threshold value, calibrate the rough filling weight by correcting the pulse number of the first filling machine; The target set weight is subtracted from the final weight to obtain the drop difference weight of the packaged item being filled into the bag by the second filling machine, and the calculated filling weight obtained by subtracting the drop difference weight and the rough filling weight from the final weight is divided by the total number of pulses input to the second filling machine to calculate the filling weight per pulse of the second filling machine. correcting the number of pulses corresponding to the weight difference due to the drop from the total number of pulses input to the second filling machine, thereby calibrating the total number of pulses input to the second filling machine; A measuring and filling method characterized by the above.

2. 2. The method for measuring and filling according to claim 1, wherein the normal operation mode is executed for a predetermined operation time or a predetermined number of times, or the measuring and stabilization mode is executed depending on environmental conditions.

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