JP4043377B2 - Weighing device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a weighing device, and more particularly, to a weighing device that includes a weighing unit that measures a weight of a weighing object container by putting the weighing object in a weighing object container and performs zero point adjustment.
[0002]
[Prior art]
In general, it is considered desirable to perform combination weighing in order to perform weighing at high speed and with high accuracy. In combination weighing, a plurality of weighing hoppers (weighing object containers) are weighed by a load cell (weighing unit), and a plurality of hoppers that perform a combination calculation of each weight value to obtain a weight within a predetermined range. And collect articles from these hoppers. Thereby, an aggregate of a predetermined weight or a predetermined number of articles can be obtained.
[0003]
An apparatus for performing such combination weighing is described in Patent Document 1, for example. In this device, in order to increase the number of hoppers participating in the combination calculation and improve the weighing accuracy, a booster hopper is provided below the weighing hopper having two gates, and the article is opened when one of the weighing hoppers is opened. Drop from the weighing hopper to the booster hopper. At the time of the combination calculation, the combination calculation is performed using the weighing data of the articles in the weighing hopper and the weighing data of the articles in the booster hopper, and the other gate of the weighing hopper or the booster hopper gate is opened to obtain a predetermined amount. Collect the items that will become.
[0004]
Some devices that perform combination weighing handle highly sticky weighing objects such as boiled beans and pickles. These highly sticky weighing objects tend to remain on the inner surface of the weighing hopper. Then, if a new weighing object is thrown into the weighing hopper while the previous weighing object remains in the weighing hopper, a difference occurs between the actual weight and the weight value of the weighing object. This difference can be suppressed by performing a so-called zero point adjustment in which the weight value when the weighing hopper is empty after the weighing object is discharged is regarded as zero. In addition, by this zero point adjustment, it is also possible to correct zero point fluctuations caused by changes in temperature and humidity. The zero point adjustment is disclosed in Patent Document 2, for example.
[0005]
[Patent Document 1]
Japanese Patent Publication No. 6-56312
[0006]
[Patent Document 2]
Japanese Patent Publication No. 61-12523
[0007]
[Problems to be solved by the invention]
A device having a booster hopper as described in Patent Document 1 and having two gates in the weighing hopper, or providing two gates in the weighing hopper in order to distribute the weighing items from the same weighing hopper to different collecting chutes Also in the weighing device, it is highly necessary to perform zero adjustment when handling a highly sticky weighing object.
[0008]
However, in the case of a weighing device equipped with a weighing hopper provided with two or more gates, the inventor of the present application has a phenomenon that the zero point shifts depending on which gate is opened or closed. noticed. That is, when a plurality of gates are provided in the weighing hopper, even if a conventional zero adjustment method such as the device shown in Patent Document 2 is adopted, the zero adjustment may be inappropriate, resulting in a measurement failure. I realized that there is a fear.
[0009]
The subject of this invention is providing the measuring device which can perform zero point adjustment more appropriately.
[0010]
[Means for Solving the Problems]
A weighing apparatus according to a first aspect includes a weighing object container, a first opening / closing mechanism, a second opening / closing mechanism, a weighing unit, a gate control unit, and a zero point setting unit. The weighing object container accommodates a weighing object. The weighing object container has a first discharge gate and a second discharge gate. The first opening / closing mechanism is a mechanism for opening / closing the first discharge gate. The second opening / closing mechanism is a mechanism for opening / closing the second discharge gate. A first direction that is a load direction to the weighing unit due to the operation of the first opening / closing mechanism is different from a second direction that is a load direction to the weighing unit due to the operation of the second opening / closing mechanism. The weighing unit measures the weight of the weighing object container. The gate control unit opens and closes the first discharge gate to discharge the weighing object to the first discharge place, and opens and closes the second discharge gate to discharge the weighing object to the second discharge place. The zero point setting unit receives the weight value from the weighing unit and adjusts the zero point when calculating the weight of the weighing object. The zero point setting unit adjusts the zero point according to the first direction and the second direction.
[0011]
Generally, the weighing unit does not return completely to the original state when the load applied immediately before is released. Therefore, the weight value of the weighing unit needs to be corrected in consideration of the fact that the load has been applied immediately before, taking into account that the weighing unit has not completely returned to the original state. This correction can be made by zero adjustment.
On the other hand, here, the force when the first / second opening / closing mechanism for opening / closing the first / second discharge gate of the weighing object container is operated causes a load to be applied to the measuring unit and affects the measuring unit.
[0012]
And here, the first direction that is the load direction to the weighing unit due to the operation of the first opening and closing mechanism, and the second direction that is the load direction to the weighing unit due to the operation of the second opening and closing mechanism, Is different. For this reason, the magnitude | size and / or directionality of the influence which the action | operation of a 1st opening / closing mechanism has on a measurement part and the influence which the action | operation of a 2nd opening / closing mechanism has on a measurement part differ.
[0013]
In view of this, the zero point setting unit performs the zero point adjustment according to the first direction and the second direction. For this reason, in the weighing device according to the first aspect, the zero point adjustment can be performed more appropriately.
A weighing apparatus according to a second aspect is the weighing apparatus according to the first aspect, wherein the first direction includes a vertically upward component. The second direction does not include a vertically upward component.
[0014]
Generally, a vertical downward force often acts on the measuring unit, and in principle, a vertical upward force does not act. Therefore, the conventional zero adjustment is often performed on the premise that a vertically downward force is temporarily applied to the weighing unit by opening / closing the weighing object or the gate.
However, here, with the operation of the first opening / closing mechanism when opening / closing the first discharge gate, a load acts on the weighing unit in the first direction including the vertically upward component. As described above, when a load including a vertically upward component is applied to the measuring unit, it is often necessary to adjust the zero point in the opposite direction compared to when a load including a vertically downward component is applied to the measuring unit. Become. Therefore, when a load in the first direction including such a vertically upward component is applied to the measuring unit, the zero point adjustment is performed on the premise that a vertically downward force is applied to the measuring unit as in the past. So that adjustment would be inappropriate.
[0015]
On the other hand, in the present invention, the zero point adjustment according to the first direction and the second direction is performed, so the zero point adjustment is appropriate.
A weighing device according to a third aspect is the weighing device according to the first or second aspect, wherein the zero point setting unit has a correction value. The correction value is obtained based on the weight value from the weighing unit after the first opening / closing mechanism is actuated and the weight value from the weighing unit after the second opening / closing mechanism is actuated. The zero point setting unit corrects the zero point with the correction value after at least one of the operation of the first opening / closing mechanism and the operation of the second opening / closing mechanism.
[0016]
Here, the operation of the first and / or second opening / closing mechanism is monitored, and the zero point is corrected by the correction value after at least one of the operations. Therefore, the zero adjustment can be appropriately performed in consideration of the different effects of the first and second opening / closing mechanisms on the measuring unit.
Note that only one correction value may be determined from the difference between the influence of the first opening / closing mechanism on the measuring section and the influence of the second opening / closing mechanism on the measuring section, or the influence of the first opening / closing mechanism on the measuring section. The first correction value in consideration of the above and the second correction value in consideration of the influence of the second opening / closing mechanism on the measuring unit may be determined.
[0017]
A weighing device according to claim 4 is the weighing device according to claim 3, wherein the zero point setting unit periodically opens and closes the first discharge gate and the second discharge gate by the gate control unit to update the correction value. To do.
Here, not only the zero point is corrected by a fixed correction value as verified in advance, but the correction value is periodically updated by actually moving the discharge gate. For this reason, it becomes possible to correct the zero point by using a correction value that matches the actual latest use situation and the like, and it can be expected that the zero point adjustment is performed more appropriately.
[0018]
A weighing device according to a fifth aspect includes a weighing object container, a weighing unit, and a zero point setting unit. The weighing object container accommodates a weighing object. The weighing unit measures the weight of the weighing object container. The zero point setting unit receives the weight value from the weighing unit and adjusts the zero point when calculating the weight of the weighing object. The zero point setting unit adjusts the zero point according to the direction of the force temporarily acting on the weighing unit after something other than the weighing object temporarily exerts a force on the weighing unit.
[0019]
Generally, the weighing unit does not return completely to the original state when the load applied immediately before is released. Therefore, the weight value of the weighing unit needs to be corrected in consideration of the fact that the load has been applied immediately before, taking into account that the weighing unit has not completely returned to the original state. This correction can be made by zero adjustment.
In general, a vertical downward force often acts on the measuring unit, and as a rule, a vertical upward force does not act. Therefore, the conventional zero adjustment is often performed on the premise that a vertically downward force is temporarily applied to the weighing unit by opening / closing the weighing object or the gate.
[0020]
However, when a force including a vertically upward component is applied to the measuring unit, it is often necessary to adjust the zero point in the opposite direction compared to when a force including a vertically downward component is applied to the measuring unit. Therefore, when such a force including a vertically upward component is applied to the measuring unit, if zero adjustment is performed on the premise that a vertically downward force is applied to the measuring unit as in the past, the adjustment Would be inappropriate.
[0021]
On the other hand, here, after something other than the weighing object temporarily exerts a force on the weighing unit, the zero point setting unit adjusts the zero point according to the direction of the force acting on the weighing unit temporarily. is doing. Thus, by taking into account the direction of the force acting on the measuring section temporarily, erroneous zero adjustment and insufficient zero adjustment can be suppressed, and the zero adjustment becomes more appropriate.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a schematic side view of a combination weighing device 1 according to an embodiment of the present invention. The combination weighing device 1 includes a plurality of weighing hoppers 5 and booster hoppers 6. Each weighing hopper 5 measures the weight of an article (weighed item) such as food, and the weight values are combined and calculated to obtain a predetermined allowable range. Several hoppers are selected so that the weight is within the range, and the articles are gathered and discharged.
[0023]
<Configuration of combination weighing device>
The combination weighing device 1 includes a dispersion feeder 2, a radiation feeder 3, a pool hopper 4, a weighing hopper 5, a booster hopper 6, a collecting chute 7, a control unit 30 (see FIG. 2), a main body frame 10 that supports the feeder and the hopper, and the like. It is configured.
[Distributed feeder]
The dispersion feeder 2 is a flat conical table-shaped member. The dispersion feeder 2 receives an article supplied from a supply conveyor 90 disposed above it. The dispersion feeder 2 is vibrated by the electromagnet incorporated in the lower part thereof, and conveys the article supplied from the supply conveyor 90 while being dispersed in the radial direction. The article conveyed by the dispersion feeder 2 is transferred onto a plurality of radiation feeders 3 arranged on the outer peripheral side of the dispersion feeder 2.
[0024]
[Radiation feeder]
The plurality of radiation feeders 3 are sheet metal members formed by bending a stainless steel plate, and are arranged at equal intervals around the dispersion feeder 2. Each radiating feeder 3 is also vibrated by an electromagnet incorporated in the lower part thereof, conveys the article outward, and supplies the article to the corresponding pool hopper 4.
[0025]
[Pool hopper]
Each of the pool hoppers 4 is associated with the radiation feeder 3 and is disposed below the outer end portion of the radiation feeder 3. And the pool hopper 4 receives supply of articles | goods from the radiation feeder 3, and stores it temporarily. The pool hopper 4 opens a lower gate according to an instruction from a control unit 30 (described later) and supplies articles to the weighing hopper 5.
[0026]
[Weighing hopper]
The weighing hoppers 5 are respectively associated with the pool hoppers 4 and are disposed below the pool hoppers 4. The weighing hopper 5 is mainly composed of a main body casing 5c, a hook arm 5d, a first discharge gate 5a, and a second discharge gate 5b. A container shape is formed by closing the lower opening of the main casing 5 c with the first discharge gate 5 a and the second discharge gate 5 b, and articles can be stored in the weighing hopper 5. One end of the hook arm 5d is fixed to the side wall of the main casing 5c, and the other end is hooked to the end of the measuring support member 11 extending from the load cell 12 (see FIGS. 3 and 5). That is, the weighing hopper 5 is supported by the load cell 12 via the weighing support member 11.
[0027]
(Load cell)
The load cell 12 measures the weight of the weighing hopper 5, the articles in the weighing hopper 5, the weight of each link member of the first / second opening / closing mechanisms 50a, 50b for opening / closing first / second discharge gates 5a, 5b, which will be described later. 1 is a scale capable of measuring the force from the supporting member 11, and is disposed inside each weighing hopper 5 as shown in FIG. The fixed end of the load cell 12 is fixed to the main body frame 10. A weighing support member 11 is fixed to the free end of the load cell 12. The weighing support member 11 has a weighing hopper support portion at an outer peripheral side end portion thereof, and supports the hooking arm 5d of the weighing hopper 5 by this support portion.
[0028]
(First / second discharge gate)
Moreover, the 1st discharge gate 5a and the 2nd discharge gate 5b provided in the lower part of the main body casing 5c each open and close separately. The first discharge gate 5a is a gate for dropping articles in the weighing hopper 5 onto the collecting chute 7, and is opened and closed by a first opening / closing mechanism 50a based on a command from the control unit 30 described later. The second discharge gate 5b is a gate for dropping and moving articles in the weighing hopper 5 into the booster hopper 6, and is opened and closed by a second opening / closing mechanism 50b based on a command from the control unit 30 described later.
[0029]
(First opening / closing mechanism)
As shown in FIGS. 3, 4, 7, and 8, the first opening / closing mechanism 50a for opening / closing the first discharge gate 5a mainly includes a motor 51, a first cam 51a, and a first link member 52. The second link member 53, the third link member 54, the first spring 55, the pin support member 56, the first roller member 71, the fourth link member 72, the fifth link member 73, and the sixth The link member 74 is comprised.
[0030]
The motor 51 rotates the first cam 51a according to a command from the control unit 30 described later.
The first cam 51a is forced against the lower end 52a of the first link member 52 so that the first link member 52 rotates about the rotation shaft 52b and changes from the state shown in FIG. 7 to the state shown in FIG. Add F1. This force F1 is generally an obliquely downward force including a vertically downward component (see FIG. 8).
[0031]
The first link member 52 is pin-supported to the measuring support member 11 by a rotating shaft 52b and is pin-joined to the upper end of the second link member 53 by an upper end 52c.
The second link member 53 has a spring supported portion 53a that is pulled downward by the first spring 55, and is always pulled downward. Thereby, when the torque is not acting from the motor 51 to the 1st cam 51a, the 1st link member 52, the 2nd link member 53, etc. return naturally from the state shown in FIG. 8 to the state shown in FIG. Become.
[0032]
The third link member 54 has a V-shape, is pin-supported by the measuring support member 11 by the rotating shaft 54 b, and one end 54 a is pin-joined to the lower end of the second link member 53. . Accordingly, when the lower end of the second link member 53 moves up from the state shown in FIG. 7 to the state shown in FIG. 8, the third link member 54 rotates about the rotation shaft 54b, and the third link member 54 The U-shaped portion 54c at the other end rotates in the direction of arrow R12 in FIG.
[0033]
The first spring 55 is a component that applies a downward force to the second link member 53 as described above, and the lower end thereof is pin-supported by the measuring support member 11 by the pin support member 56.
The upper and lower surfaces of the first roller member 71 are supported by the U-shaped portion 54 c at the other end of the third link member 54. However, the first roller member 71 can move in and out from the tip portion of the U-shaped portion 54c. The first roller member 71 is supported by the lower end 72a of the fourth link member 72, as shown in FIGS.
[0034]
As for the 4th link member 72, while the center rotating shaft 72b is pin-supported by the main body casing 5c of the measurement hopper 5, the edge part 72c on the opposite side to the lower end 72a is pin-joined to the end of the 5th link member 73. ing. The other end of the fifth link member 73 is pin-bonded to one end of the sixth link member 74. The other end of the sixth link member 74 is fixed to the upper end of the first discharge gate 5a. When the first roller member 71 rises while turning and shifts from the state shown in FIG. 3 to the state shown in FIG. 4, the fourth link member 72 rotates to the sixth link member 74 via the fifth link member 73. The force acts, the sixth link member 74 and the first discharge gate 5a rotate, and the first discharge gate 5a is opened as shown in FIG. As a result, the article stored in the weighing hopper 5 in the state shown in FIG. 3 falls onto the collective chute 7 as indicated by the white arrow A1 in FIG.
[0035]
(Second opening / closing mechanism)
As shown in FIGS. 5, 6, 9, and 10, the second opening / closing mechanism 50b for opening / closing the second discharge gate 5b mainly includes a motor 51 shared with the first opening / closing mechanism 50a, and a second cam 51b. A seventh link member 62, an eighth link member 63, a ninth link member 64, a tenth link member 65, a second spring 66, a pin support member 67, a second roller member 81, 11 link member 82 and rotating shaft 83.
[0036]
The motor 51 rotates the second cam 51b according to a command from the control unit 30 described later. The shaft rotation direction of the motor 51 for opening the second discharge gate 5b is opposite to the shaft rotation direction of the motor 51 for opening the first discharge gate 5a.
The second cam 51b has a force applied to the upper end 62a of the seventh link member 62 so that the seventh link member 62 rotates about the rotation shaft 62b and changes from the state shown in FIG. 9 to the state shown in FIG. Add F2. This force F1 is generally an obliquely upward force including a vertically upward component (see FIG. 10).
[0037]
The seventh link member 62 is pin-supported by the measuring support member 11 by the rotation shaft 62b, and is pin-connected to the upper end of the V-shaped eighth link member 63 by the lower end 62c. The seventh link member 62 includes a spring supported portion 62d that is pulled outward in the radial direction of the combination weighing device 1 by the second spring 66, and is always pulled. Thus, when no torque is applied from the motor 51 to the second cam 51b, the seventh link member 62 and the like naturally return from the state shown in FIG. 10 to the state shown in FIG.
[0038]
The eighth link member 63 has a V-shape, and the rotation shaft 63 b at one end thereof is pin-supported by the measurement support member 11. The central portion 63 a of the eighth link member 63 is pin-joined to the upper end of the ninth link member 64. As described above, the upper end of the eighth link member 63 is pin-bonded to the lower end 62 c of the seventh link member 62.
[0039]
The tenth link member 65 has a V shape, and one end 65 a thereof is pin-bonded to the lower end of the ninth link member 64. Further, the central rotation shaft 65 b of the tenth link member 65 is pin-supported by the measuring support member 11. Accordingly, when the lower end of the ninth link member 64 shifts from the state shown in FIG. 9 to the state shown in FIG. 10, the tenth link member 65 rotates about the rotation shaft 65 b, and the tenth link member 65. The U-shaped portion 65c at the other end rotates in the direction of arrow R22 in FIG.
[0040]
The second spring 66 is a component that constantly applies force to the seventh link member 62 as described above, and one end of the second spring 66 is pin-supported by the measuring support member 11 by the pin support member 67.
The upper and lower surfaces of the second roller member 81 are supported by the U-shaped portion 65 c at the other end of the tenth link member 65. However, the second roller member 81 can move in and out from the distal end portion of the U-shaped portion 65c. The second roller member 81 is supported at the tip of the eleventh link member 82 as shown in FIGS.
[0041]
The rotating shaft 83 pin-supports the upper part of the second discharge gate 5b on the main body casing 5c of the weighing hopper 5. That is, the second discharge gate 5b can rotate around the rotation shaft 83. An eleventh link member 82 is fixed to the outer surface of the second discharge gate 5b.
When the U-shaped portion 65c rises due to the rotation of the tenth link member 65, the second roller member 81 rises while turning and changes from the state shown in FIGS. 5 and 9 to the state shown in FIGS. Then, a force acts on the second discharge gate 5b from the eleventh link member 82, the second discharge gate 5b rotates about the rotation shaft 83, and the second discharge gate 5b is opened as shown in FIG. It becomes. Thereby, the article stored in the weighing hopper 5 in the state shown in FIG. 5 falls into the booster hopper 6 as indicated by the white arrow A2 in FIG.
[0042]
[Booster Hopper]
Each of the booster hoppers 6 is disposed below the second discharge gate 5b of each weighing hopper 5, and temporarily stores articles transferred from the weighing hopper 5. The articles stored in the booster hopper 6 are subjected to combination calculation by the control unit 30 together with the articles in the weighing hopper 5. When the booster hopper 6 opens the lower gate, articles in the booster hopper 6 fall onto the collecting chute 7.
[0043]
[Gathering shoot]
The funnel-shaped collecting chute 7c collects articles falling from the weighing hopper 5 and the booster hopper 6 downward and discharges them from the lower discharge port 7a.
[Control unit]
The control unit 30 performs a combination calculation process based on the measurement signal from the load cell 12 and controls the movement of each unit. As shown in FIG. 2, the control unit 30 includes a CPU 31, ROM 32, RAM 33, multiplexer 34, A / D converter 35, DSP (digital signal processor) 36, and the like.
[0044]
The CPU 31 which is a central processing unit performs zero adjustment and combination calculation of the measured measurement value, and issues a command to each unit. The ROM 32 and RAM 33 are main storage devices controlled by the CPU 31. The multiplexer 34 is a device that selects one measurement signal from a plurality of measurement signals from the load cell 12 amplified by the amplifier 12a. The A / D converter 35 is a device that converts a measurement signal, which is an analog signal, into a digital signal. The DSP 36 is a device that processes the measurement signal, and mainly filters the measurement signal from the A / D converter 35. The CPU 31 is mutually connected to the ROM 32, the RAM 33, the DSP 36, and the like via a bus line.
[0045]
The weight of the article held in each weighing hopper 5 is measured by the load cell 12. The measurement signal output from the load cell 12 and amplified by the amplifier 12a is sent to the multiplexer 34 as needed. When a signal for selecting a weighing measurement signal of a certain load cell 12 is sent from the CPU 31 among the weighing measurement signals, the multiplexer 34 sends the weighing measurement signal of the load cell 12 designated by the CPU 31 to the A / D converter 35. The A / D converter 35 converts the measurement signal that is an analog signal into a digital signal. The DSP 36 receives the digital measurement signal from the A / D converter 35 and filters the measurement signal. The CPU 31 obtains a measurement value that is the magnitude of the force acting on the load cell 12 based on the filtered measurement signal sent from the DSP 36.
[0046]
<Operation of combination weighing device>
In the combination weighing device 1, the heads including the pool hopper 4, the weighing hopper 5, and the booster hopper 6 are arranged at equal intervals in the circumferential direction. The control unit 30 grasps the weights of articles accommodated in the weighing hopper 5 and the booster hopper 6 based on the weighing measurement signal from the load cell 12, and then performs a combination calculation to select a plurality of hoppers 5, 6 selected. The articles are dropped to the collecting chute 7 to collect and discharge.
[0047]
Specifically, an appropriate amount of articles supplied from the supply conveyor 90 and transported to the pool hopper 4 by the dispersion feeder 2 and the radiation feeder 3 are used when the weighing hopper 5 located under the pool hopper 4 is empty. , Moved from the pool hopper 4 to the weighing hopper 5. When the weighing hopper 5 holds the article, the weighing measurement signal is output from the load cell 12 as described above, and the CPU 31 finally obtains the weighing measurement value from the weighing measurement signal filtered by the DSP 36.
[0048]
The measured measurement value acquired here is subjected to a zero point adjustment process (see FIG. 12) as described later, and is stored in the RAM 33 in association with the weighing hopper 5 as an article weight value. The article weight value stored in the RAM 33 is newly stored in the RAM 33 in association with the booster hopper 6 when the corresponding article moves from the weighing hopper 5 to the booster hopper 6.
[0049]
Using the article weight values associated with the weighing hopper 5 and the booster hopper 6, the CPU 31 performs a combination operation so that the articles to be collected on the collective chute 7 have a preset target weight value. In the processing of this combination calculation, the CPU 31 causes the total of the article weight values in the hopper to match the target weight value from the weighing hopper 5 and the booster hopper 6 or close to the target weight value within an allowable range. In addition, several (for example, three) hoppers are selected.
[0050]
When a plurality of hoppers are selected, the CPU 31 drops the articles in those hoppers and collects them by the collecting chute 7. The assembled articles are discharged from the discharge port 7a below the collecting chute 7 and supplied to a bag making and packaging machine or the like.
[Initial setting of zero value and zero correction value]
Next, an initial setting process for preliminarily determining a reference zero value S0 and a zero correction value A0 used when the measurement value is subjected to zero adjustment processing (described later) to obtain an article weight value will be described. By this processing, the reference zero value S0 and the zero correction value A0 are determined for each weighing hopper 5 and stored in the RAM 33.
[0051]
As shown in FIG. 11, in the initial setting process, as shown in steps S1 to S3, the operation of opening and closing the first discharge gate 5a after opening and closing the second discharge gate 5b is repeated twice. Although the number of repetitions is two here, the number of repetitions may be set so that the discharge gates 5b and 5a are alternately opened and closed.
Thereafter, the process proceeds to step S4, and the CPU 31 stores the reference zero value S0 in the RAM 33. Here, weighing is performed by the load cell 12 in an empty state where there is no article in the weighing hopper 5, and the CPU 31 obtains a measured measurement value from the measured measurement signal. This measured measurement value is stored in the RAM 33 as the reference zero value S0. As shown in FIG. 8, the reference zero point value S0 is the effect of the first discharge gate 5a being opened and closed and the oblique downward force F1 including the vertically downward component acting on the load cell 12 via the measuring support member 11. Is taken into account.
[0052]
When the storage of the reference zero value S0 in step S4 is completed, the second discharge gate 5b is then opened and closed in step S5. As a result, the load cell 12 remains affected by the diagonally upward force F2 including the vertically upward component as shown in FIG. In this state, in step S6, the zero point correction value A0 is obtained and stored in the RAM 33. This zero point correction value A0 is the difference between the measured measurement value acquired by the CPU 31 after step S5 and the measured measurement value acquired in step S4.
[0053]
The measurement value acquired by the CPU 31 after step S5 includes the influence of the diagonally upward force F2 including the vertically upward component acting on the load cell 12, and the measurement value acquired in step S4 is the vertically downward component. This includes the influence of the diagonally downward force F <b> 1 acting on the load cell 12. Therefore, these two measurement values are different, and there is a difference between them, that is, a zero correction value A0. If this zero point correction value A0 is stored in the RAM 33, it is possible to calculate an appropriate article weight value in the following zero measurement adjustment process of the measured measurement value.
[0054]
[Weighing measurement value zero adjustment]
Next, processing for obtaining the weight of only the article in the weighing hopper 5 as the article weight value using the reference zero value S0 and the zero point correction value A0 based on the measurement value obtained from the measurement signal of the load cell 12 will be described. To do.
The CPU 31 acquires a measurement value from the measurement signal output from the load cell 12 and finally filtered by the DSP 36. The measurement values include the weighing hopper 5, the articles in the weighing hopper 5, the weight of each link member of the first / second opening / closing mechanisms 50a, 50b for opening / closing the first / second discharge gates 5a, 5b, Since the weight of the support member 11 and the like is included, it is necessary to perform processing for calculating only the weight of the article in the weighing hopper 5 (hereinafter referred to as the article weight value) from the measured measurement value. Here, as shown in FIG. 12, the zero point adjustment process for obtaining the article weight value from the measured measurement value is performed.
[0055]
First, in step S11, it is confirmed which discharge gate was opened and closed last time for the target weighing hopper 5. If the first discharge gate 5a was previously opened and closed, the process proceeds to step S12, and the article weight value is calculated by subtracting the reference zero value S0 from the measured measurement value. As described above, the reference zero value S0 is a measurement value obtained on the basis of the measurement signal from the load cell 12 in an empty state where there is no article in the measurement hopper 5, and therefore, the reference zero value S0 is obtained from the measurement value. If it pulls, the weight of the thing (article) in the measurement hopper 5 will be calculated. Further, the reference zero value S0 is a measured value after the first discharge gate 5a is opened and closed and the diagonally downward force F1 is applied to the load cell 12, so that the first discharge gate 5a was previously opened and closed. It matches the condition of step S12.
[0056]
On the other hand, if it is determined in step S11 that the second discharge gate 5b was previously opened and closed, the process proceeds to step S13. In step S13, the article weight value is calculated by subtracting the reference zero value S0 from the measured measurement value and adding the zero correction value AO. The zero point correction value AO is a measured value immediately after the first discharge gate 5a is opened and closed and the diagonally downward force F1 is applied to the load cell 12, and the second discharge gate 5b is opened and closed and the vertically upward component. Is the difference from the measured measurement value immediately after the diagonally upward force F2 including is applied to the load cell 12. Therefore, by calculating the article weight value in consideration of the zero point correction value A0, the article weight value becomes appropriate in accordance with the condition that the second discharge gate 5b was previously opened and closed.
[0057]
The article weight value calculated by such zero point adjustment processing is temporarily stored in the RAM 33 and used in the combination calculation.
[Update processing of zero value and zero correction value]
Next, the update process of the reference zero point value S0 and the zero point correction value A0 performed periodically will be described.
[0058]
When the combination weighing device 1 continues to operate, if the weighing hopper 5 does not hold an article, the measurement value obtained from the measurement signal of the load cell 12 under the condition that the first discharge gate 5a was opened and closed last time. Coincides with the reference zero value S0, and the measurement value obtained from the measurement signal of the load cell 12 when the second discharge gate 5b was previously opened and closed coincides with the difference between the reference zero value S0 and the zero correction value A0. It should be. However, when the article remains attached to the inner surface of the weighing hopper 5, these coincidence does not hold. That is, if the combination weighing device 1 is continuously used, if the reference zero value S0 and the zero correction value A0 obtained in the initial setting (see FIG. 11) are used, the zero adjustment process as shown in FIG. 12 is performed. Even if it goes, there will be a situation where the correct article weight value is not calculated.
[0059]
In order to suppress such a problem, the combination weighing device 1 periodically performs the update process of the reference zero value S0 and the zero correction value A0 shown in FIG. This update process may be performed on the empty weighing hopper 5 when the combination weighing process is continued, or may be performed when the combination weighing process is interrupted. However, in any case, the update processing of the reference zero value S0 and the zero point correction value A0 is performed on the empty weighing hopper 5 in which no article is contained, and the weighing hopper 5 in the state in which the article is contained Update processing cannot be performed.
[0060]
As shown in FIG. 13, in the update process of the reference zero value S0 and the zero point correction value A0, first, in step S21, it is confirmed which discharge gate was opened / closed last time for the empty weighing hopper 5. If the first discharge gate 5a was previously opened and closed, the process proceeds to step S22, and the reference zero value S0 is updated based on the measured measurement value at that time. On the other hand, if the second discharge gate 5b has been opened and closed last time, the process proceeds to step S23, and the zero correction value A0 is updated based on the measured measurement value and the reference zero value S0 at that time.
[0061]
<Features of combination weighing device>
(1)
Generally, the load cell does not return completely to the original state when the load applied immediately before is released. Therefore, the weighing measurement signal output from the load cell and the weighing measurement value obtained from the signal are corrected in consideration of the fact that the load has been applied immediately before, taking into account that the load cell has not completely returned to the original state. There is a need. This correction is conventionally performed by so-called zero point adjustment. Since the force that temporarily acts on the free end of the load cell by opening / closing the weighing object or the gate is generally vertically downward, the conventional zero adjustment is performed on the premise of this.
[0062]
On the other hand, in the combination weighing device 1 of the present embodiment, when the first discharge gate 5a is opened and closed, an obliquely downward force F1 (see FIG. 8) including a vertically downward component is passed through the weighing support member 11. However, there is a special situation that when the second discharge gate 5b is opened and closed, an obliquely upward force F2 (see FIG. 10) including a vertically upward component acts on the load cell 12. That is, the opening / closing of the first discharge gate 5a by the first opening / closing mechanism 50a exerts on the load cell 12 (see force F1 in FIG. 8), and the opening / closing of the second discharge gate 5b by the second opening / closing mechanism 50b exerts on the load cell 12. The force (see force F2 in FIG. 10) is different in magnitude and direction.
[0063]
Therefore, after the first discharge gate 5a is opened and closed, the article weight value may be calculated from the measurement value based on the reference zero value S0 as usual, but the second discharge gate 5b is opened and closed. Later, if the article weight value is calculated from the measured measurement value based only on the reference zero value S0 as in the conventional case, the measurement accuracy may not be ensured.
[0064]
In view of this, here, the reference zero value S0 is set on the assumption that the first discharge gate 5a is opened and closed, and the zero adjustment is performed after the second discharge gate 5b is opened and closed. For the zero point adjustment process (step S13 shown in FIG. 12), a zero correction value A0 derived from the measured measurement value after opening / closing the first discharge gate 5a and the measured measurement value after opening / closing the second discharge gate 5b is set. is doing. Since the zero point adjustment is performed by the method as shown in FIG. 12, after the second discharge gate 5b is opened and closed and the diagonally upward force F2 (see FIG. 10) including the vertically upward component is applied to the load cell 12, However, an appropriate zero adjustment that takes this into account is made.
[0065]
Thus, here, the CPU 31 of the control unit 30 confirms the opening / closing of the first discharge gate 5a by the first opening / closing mechanism 50a and the opening / closing of the second discharge gate 5b by the second opening / closing mechanism 50b (step S11 in FIG. 12). After the opening and closing of the first discharge gate 5a, zero adjustment is performed to calculate the article weight value using only the reference zero point S0, and after the opening and closing of the second discharge gate 5b, the reference zero point S0 is corrected with the zero correction value A0. Since the zero point adjustment for calculating the article weight value is performed by using the shape, the zero point adjustment is appropriately performed even after any of the discharge gates 5a and 5b is opened and closed.
[0066]
(2)
In the combination weighing device 1 of the present embodiment, not only the zero adjustment is performed based on the reference zero value S0 and the zero correction value A0 obtained by the initial setting shown in FIG. 11, but based on the measurement signal from the load cell 12 periodically. The reference zero point value S0 and the zero point correction value A0 are updated (see FIG. 13). For this reason, the zero point adjustment is performed more appropriately.
[0067]
<Modification>
(A)
In the above embodiment, the present invention is applied to the combination weighing device 1 including the weighing hopper 5 that drops articles from the one gate 5a to the collecting chute 7 and drops articles from the other gate 5b to the booster hopper 6. The present invention may be applied to a combination weighing device including a weighing hopper that drops an article from the gate to the first collecting chute and drops an article from the other gate to the second collecting chute.
[0068]
(B)
In the above embodiment, the motor 51 is shared by the first opening / closing mechanism 50a for opening / closing the first discharge gate 5a and the second opening / closing mechanism 50b for opening / closing the second discharge gate 5b, but the respective opening / closing mechanisms 50a, 50b. It is also possible to use another motor.
[0069]
(C)
In the above embodiment, instead of the adjustment value used in the conventional zero adjustment, the first discharge gate 5a is opened and closed, and the reference zero value S0 including the effect of the diagonally downward force F1 acting on the load cell 12 is obtained. The opening and closing of the discharge gate 5a is performed and the diagonally downward force F1 is applied to the load cell 12, and the opening and closing of the second discharge gate 5b is performed and the diagonally upward force F2 including the vertically upward component is applied to the load cell 12. Using the zero correction value A0 reflecting the difference from the influence, the zero adjustment process (see FIG. 12) of the measured measurement value is performed.
[0070]
Instead of the zero adjustment process of the measured measurement value based on the reference zero value S0 and the zero correction value A0, as shown in FIG. 14, the zero adjustment value S01 and the zero adjustment value S01 which are the same as those in the prior art are used as the first opening / closing mechanism. The first correction value A01, which is the amount of change that changes after the first discharge gate 5a is opened and closed by 50a, and the second correction amount A01 that is the amount of change that changes after the second discharge gate 5b is opened and closed by the second opening / closing mechanism 50b. The zero value adjustment process of the measured measurement value may be performed using the correction value A02. In this case, the discharge gate that was opened / closed last time is confirmed in step S51, and when the first discharge gate 5a was opened / closed last time, the first correction value A01 is added to the value obtained by subtracting the zero adjustment value S01 from the measured measurement value. The weight value is calculated (step S52), and when the second discharge gate 5b was previously opened and closed, the article weight value is calculated by adding the second correction value A02 to the value obtained by subtracting the zero adjustment value S01 from the measured measurement value. (Step S52). Here, it is assumed that one of the first correction value A01 and the second correction value A02 is a positive value and the other is a negative value.
[0071]
(D)
In the above embodiment, the update process of the reference zero value S0 and the zero point correction value A0 shown in FIG. 13 is one of the update processes. Instead, during the regular update process, the discharge gates 5a and 5b are actively opened and closed so that the values S0 and A0 are obtained so that both the reference zero value S0 and the zero correction value A0 are always updated. You may do it.
[0072]
【The invention's effect】
In the present invention, the first direction that is the load direction to the weighing unit due to the operation of the first opening / closing mechanism and the second direction that is the load direction to the weighing unit due to the operation of the second opening / closing mechanism are different from each other. Since zero adjustment is performed in accordance with the first direction and the second direction, zero adjustment in the weighing device is appropriate.
[Brief description of the drawings]
FIG. 1 is a schematic side view of a combination weighing device according to an embodiment of the present invention.
FIG. 2 is a control block diagram of the combination weighing device.
FIG. 3 is a side view showing a portion on the weighing hopper side of the first opening / closing mechanism (first discharge gate closed).
FIG. 4 is a side view showing a portion on the weighing hopper side of the first opening / closing mechanism (first discharge gate opened).
FIG. 5 is a side view showing a portion on the weighing hopper side of the second opening / closing mechanism (second discharge gate closed).
FIG. 6 is a side view showing a portion on the weighing hopper side of the second opening / closing mechanism (second discharge gate opened).
FIG. 7 is a side view showing a portion on the load cell side of the first opening / closing mechanism (first discharge gate closed).
FIG. 8 is a side view showing a portion on the load cell side of the first opening / closing mechanism (first discharge gate opened);
FIG. 9 is a side view showing a portion on the load cell side of the second opening / closing mechanism (second discharge gate closed).
FIG. 10 is a side view showing a portion of the second opening / closing mechanism on the load cell side (second discharge gate opened).
FIG. 11 is a flowchart showing initial setting processing of a zero value and a zero correction value.
FIG. 12 is a flowchart showing a zero adjustment process of a measured measurement value.
FIG. 13 is a flowchart showing a zero value and zero point correction value update process.
FIG. 14 is a flowchart showing a zero adjustment process of a measured measurement value in Modification (C).
[Explanation of symbols]
1 Combination weighing device
5 Weighing hopper (weighing object container)
5a First discharge gate
5b Second discharge gate
6 Booster hopper (second discharge location)
7 Collective chute (first discharge location)
12 Load cell (weighing unit)
30 control unit (zero point setting unit; gate control unit)
50a First opening / closing mechanism
50b Second opening / closing mechanism
F1 Diagonal downward force acting on the load cell by opening and closing the first discharge gate
F2 Diagonally upward force acting on the load cell by opening and closing the second discharge gate
S0 Reference zero value (zero point)
S01 Zero adjustment value (zero)
A0 Zero point correction value (correction value)
A01 First correction value (correction value)
A02 Second correction value (correction value)

Claims (5)

A weighing object container having a first discharge gate and a second discharge gate, and for holding a weighing object;
A first opening / closing mechanism for opening and closing the first discharge gate;
A second opening / closing mechanism for opening / closing the second discharge gate;
A weighing unit for measuring the weight of the weighing object container;
A gate controller that opens and closes the first discharge gate to discharge the weighing object to the first discharge location, and opens and closes the second discharge gate to discharge the measurement item to the second discharge location;
A zero point setting unit that receives a weight value from the weighing unit and adjusts a zero point when calculating the weight of the weighing object;
A weighing device comprising:
A first direction that is a load direction to the weighing unit due to the operation of the first opening and closing mechanism is different from a second direction that is a load direction to the weighing unit due to the operation of the second opening and closing mechanism,
The zero point setting unit adjusts the zero point according to the first direction and the second direction.
Weighing device. The first direction includes a vertically upward component,
The second direction does not include a vertically upward component.
The weighing device according to claim 1. The zero point setting unit is
A correction value obtained based on a weight value from the weighing unit after the first opening / closing mechanism is activated and a weight value from the weighing unit after the second opening / closing mechanism is activated;
After at least one of the operation of the first opening / closing mechanism and the operation of the second opening / closing mechanism, the zero point is corrected by the correction value;
The weighing device according to claim 1 or 2. The zero point setting unit updates the correction value by periodically opening and closing the first discharge gate and the second discharge gate by the gate control unit,
The weighing device according to claim 3. A weighing object container for holding a weighing object;
A weighing unit for measuring the weight of the weighing object container;
A zero point setting unit that receives a weight value from the weighing unit and adjusts a zero point when calculating the weight of the weighing object;
With
The zero point setting unit temporarily adjusts the zero point according to the direction of the force acting on the weighing unit after a force other than the weighing object temporarily acts on the weighing unit.
Weighing device.

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