JP5627267B2 - Combination scale - Google Patents

Description

  The present invention relates to a combination weigher that measures the weight of an object to be weighed.

  2. Description of the Related Art Conventionally, there is a manual combination weigher that manually supplies and removes an object to be weighed (see, for example, Patent Documents 1 and 2).

  In the case of such a manual combination weigher, a plurality of weighing pans equipped with load detectors such as load cells are provided, and when an operator places a weighing object on each weighing pan, the weight of the weighing object for each weighing pan. Are weighed by the load detector, and a combination operation based on the weighing value of each weighing pan is performed. Then, when an appropriate amount combination in which the total weight of the objects to be weighed is within a predetermined weight range, each weighing pan corresponding to the combination turns on a combination lamp provided in the vicinity of each weighing pan, so that the operator can The object to be weighed is taken out from the weighing pan whose combination lamp is lit.

  However, in such a combination weigher, since an expensive load cell is attached to each weighing pan, the same number of load cells as the number of weighing pans are required, which increases the manufacturing cost.

  Therefore, the present applicant has already proposed a combination weigher in which the weight of the objects to be weighed in a plurality of weighing pans can be measured by one load cell so as to reduce the manufacturing cost (for example, Patent Document 3). reference).

JP-A-3-251725 Japanese Patent Laid-Open No. 2-10227 JP 2009-276267 A

  In the above-mentioned Patent Document 3, when an object to be weighed is placed on any one of a plurality of weighing pans to be weighed by one load cell, the load detected by the load cell to which a moment detection function is added. The center of gravity position of the object to be weighed is calculated based on the change in the moment and the change in the moment, and it is determined that the object to be weighed corresponding to the load is placed on the weighing pan corresponding to the position of the center of gravity.

  For this reason, in Patent Document 3, the object to be weighed is dropped from another weighing pan at the same time as placing the object to be weighed on one of the weighing pans to be weighed by one load cell, so-called, It is assumed that simultaneous loading / unloading is not performed, and a technique for processing when simultaneous loading / unloading occurs is not disclosed.

  However, with a manual combination weigher, there may be a case where the operator places the object to be weighed on one of the weighing pans and at the same time unloads the object to be weighed from another weighing pan. It is necessary to detect such simultaneous loading and unloading.

  The present invention has been made in view of the above points, and can detect when an object to be weighed is loaded and unloaded simultaneously on a plurality of weighing pans to be weighed by one load cell. The purpose is to do so.

  In order to achieve the above object, the present invention is configured as follows.

 (1) The combination weigher of the present invention includes a plurality of weighing platforms each having two placing parts on which an object to be weighed is placed, a plurality of load detectors that respectively detect the loads on each weighing table, and the loads. Based on a plurality of moment detecting means for detecting each moment acting on each weighing platform and the detection output of the load detector, the weight of the object to be weighed placed on the mounting unit is obtained, and the load detection Based on the detection output of the measuring device and the moment detecting means, the center of gravity position of the object to be weighed placed on or dropped from the mounting unit is obtained, and the obtained center of gravity and the mounting unit Based on the position of the center of gravity, the calculating means for obtaining the above-mentioned placing part on which the object to be weighed is placed or lowered, and the weight of the object to be weighed obtained by the computing means and the placing part, Union A combination weigher comprising a combination calculation means for performing calculation, wherein the object to be weighed is placed on one of the two placement parts and the object to be weighed on the other placement part is lowered; or In addition, an error detecting means for detecting the simultaneous loading and unloading as an error is provided, which simultaneously loads the object to be weighed from one mounting unit and places the object to be weighed on the other mounting unit.

  Simultaneous loading / unloading means placing an object to be weighed on one of the two placement parts of the weighing platform and simultaneously lowering an object to be weighed on the other placement part, This refers to the case where the object to be weighed is placed on the other placement part at the same time that the object is unloaded.

The simultaneous, the duration detecting load by the load detector is not stable until unloading the objects to be weighed of the other mounting portion after placing the objects to be weighed to one of the mounting portion, or one of the loading load detected by the load detector from down the objects to be weighed to put the objects to be weighed to the other mounting portion of the part refers to the period not stable. This simultaneous loading / unloading includes a case in which the object to be weighed on one placement unit is moved to the other placement unit within a period when the load detected by the load detector is not stable.

  According to the combination weigher of the present invention, when an operator places an object to be weighed on each placing part, the placing part on which the object is placed and the weight of the object to be weighed can be obtained. Combination calculations can be performed based on weight. Since only one expensive load detector is used to weigh the objects to be weighed on the two placement parts, the manufacturing cost can be reduced.

  In addition, if simultaneous loading of the objects to be weighed on the two loading parts occurs, the distribution of the weight of each loading part becomes unclear. However, the error detection means detects such simultaneous loading and unloading. It is possible to take appropriate measures such as informing the user.

  As another embodiment of the present invention, when an error is detected by the error detection unit, a notification unit that notifies the fact may be provided. As the notification means, for example, it is preferable to notify any one of a lamp, a buzzer, sound, a screen display, or a combination thereof.

  In this case, the operator who recognizes the occurrence of the error by the notifying means lowers all the objects to be weighed on the two placement parts of the weighing table where the error has occurred and reloads them, so that Since the weight of the object becomes clear, the error can be canceled.

 (2) In a preferred embodiment of the combination weigher of the present invention, the error detection unit is configured such that when the position of the center of gravity of the object to be weighed obtained by the calculation unit is not in a region corresponding to the two placement units, The simultaneous loading / unloading is determined.

  The region corresponding to the placement unit may be the region itself where the object to be weighed is placed on the placement unit, or may be a region larger than the region placed previously in consideration of error detection accuracy and the like. Good. This area is preferably preset.

  According to this embodiment, when the position of the center of gravity of the object to be weighed obtained by the calculation means is not in the area corresponding to the two placement parts, it can be detected as an error of simultaneous loading and unloading.

 (3) In a further preferred embodiment of the combination weigher of the present invention, the gravity center positions of the two placement portions of each weighing platform are arranged in a straight line, and the error detection means When the intermediate position of the part is the origin of coordinates, one mounting part side is positive, and the other mounting part side is negative, the weight change of the two mounting parts is smaller than a predetermined value. The simultaneous loading and unloading is determined when the product of the coordinates of the center-of-gravity positions of the objects to be weighed obtained by the computing means before and after the weight change is negative.

  When the change in weight is small, it is difficult to accurately determine the position of the center of gravity of the object to be weighed. In this case, the position of the center of gravity of the object to be weighed is in an area corresponding to the two placement parts. If the presence / absence of simultaneous loading / unloading is determined depending on whether or not there is, there is a possibility that accurate error detection cannot be performed.

  Therefore, in this embodiment, when the change in weight is smaller than a predetermined value and it is difficult to accurately determine the position of the center of gravity of the object to be measured, the coordinates of the position of the center of gravity of the object to be measured before and after the change in weight are obtained. Whether or not the simultaneous loading / unloading occurs is determined by whether the product is negative, that is, whether the sign of the coordinates of the center of gravity of the object to be weighed before and after the weight change is different. Even in some cases, simultaneous loading and unloading errors can be detected with high accuracy.

 (4) In another embodiment of the combination weigher of the present invention, the calculation means obtains the position of the center of gravity of the object to be measured when there is no change in load and there is a change in moment, and the error detection means When there is no change in load and there is a change in moment, the presence / absence of simultaneous loading / unloading is determined based on the change in the position of the center of gravity of the object to be weighed.

  According to this embodiment, simultaneous loading and unloading such that there is no change in load is possible, for example, even when simultaneously loading an object to be weighed of the same weight, the simultaneous loading and unloading error can be detected based on the change in moment. it can.

(5) In still another embodiment of the combination weigher according to the present invention, when an error of simultaneous loading / unloading is detected by the error detection means, the combination calculation means causes the two weighing platforms on which the error is detected to be loaded. The placement unit is integrated and regarded as one placement unit, and the combination calculation is performed.

If a simultaneous loading / unloading error occurs, the distribution of the weights of the two mounting parts becomes unclear, but the weight of the two mounting parts as a whole can be grasped. When a lowering error is detected, the two placement units in which the error is detected are integrated to participate in the combination calculation as one placement unit. Accordingly, when an error is detected, the operator does not need to perform the work of dropping and remounting the objects to be weighed on the two placement units, and the work efficiency can be improved.

(6) In the embodiment of the above (5), when all the objects to be weighed on the two mounting parts of the weighing table where the error is detected are unloaded, the combination calculating means detects the error. It is also possible to cancel the integration of the two placement units of the weighing platform and perform the combination calculation as two placement units.

According to this embodiment, the two placement parts of the weighing platform in which the simultaneous loading / unloading error is detected are integrated, and the combination calculation is performed as one placement part, and the combination is established and integrated 2 When the placement units are selected and all the objects to be weighed in the two placement units are lowered by the operator, the simultaneous loading and unloading error is canceled, and the combination calculation means detects the error. Since the integration of the two mounting parts of the weighing table is canceled and the combination calculation is performed as two mounting parts, the operator is not aware of anything from the detection of the simultaneous loading and unloading errors. Work can be continued without

  As described above, according to the present invention, an expensive load detector for measuring the weight of the objects to be weighed respectively placed on each placement unit is one weighing table having two placement units. Therefore, the number of expensive load detectors can be reduced and the manufacturing cost can be reduced.

  In addition, if simultaneous loading of the objects to be weighed on the two loading parts occurs, the distribution of the weight of each loading part becomes unclear. However, the error detection means detects such simultaneous loading and unloading. It is possible to take appropriate measures such as informing the user.

FIG. 1 is a perspective view of a combination weigher according to an embodiment of the present invention. FIG. 2 is a side view showing a schematic configuration in the vicinity of the weighing table 2 of FIG. FIG. 3 is a block diagram showing the configuration of the combination weigher 1 of FIG. FIG. 4 is a diagram for explaining simultaneous loading and unloading. FIG. 5 is a view for explaining the detection principle of simultaneous loading and unloading. FIG. 6 is a flowchart for explaining the operation of the embodiment of FIG. FIG. 7 is a flowchart for explaining the operation of another embodiment of the present invention. FIG. 8 is a flowchart for explaining the operation of the reference example .

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
FIG. 1 is a perspective view of a combination weigher according to an embodiment of the present invention.

  The combination balance 1 according to this embodiment is a manual combination balance, and includes a plurality of weighing platforms 2, a frame unit 3, and a control unit 4.

  Each weighing platform 2 has a rectangular shape extending in the left-right direction, and its intermediate portion in the left-right direction is partitioned by a partition member 6 that is one step higher, and two dishes serving as mounting portions on both the left and right sides sandwiching the partition member 6 Portions 7a and 7b are formed. An object to be weighed is placed on each plate portion 7a, 7b of each weighing platform 2 and weighed.

  In this embodiment, six weighing platforms 2 are arranged along the front-rear direction, and therefore a total of twelve plate portions 7a and 7b on which objects to be weighed are placed are arranged.

  Since this combination weigher 1 is a manual type, the operator directly loads and unloads the objects to be weighed on the respective plate portions 7a and 7b. In each weighing platform 2, the weights of the objects to be weighed placed on the pans 7a and 7b can be weighed independently as will be described later.

  The frame portion 3 is a portion that supports the weighing table 2 and the like, and a plurality of combination lamps 8 made of LEDs or the like correspond to the respective plate portions 7a and 7b of the weighing table 2 individually on the left and right sides thereof. So that it is installed along the front-rear direction. When the combination lamp 8 is turned on in green, the operator can recognize the object to be weighed selected (to be discharged), or can recognize an error or the like by blinking red. In this combination lamp 8, when the left and right lamps are clearly indicated, the combination lamps 8a and 8b will be described.

  In the center on the rear side of the frame portion 3, a reset button 9 is provided for causing the combination to be recalculated. The combination scale 1 is also provided with a buzzer (not shown).

  The control unit 4 is located in front of the frame unit 3, and a display unit 10 is provided on the front surface thereof. The display unit 10 displays a screen for setting combination conditions, a screen for combination results, and the like. Since the touch panel is employed in this embodiment, the surface portion of the display unit 10 is the input unit 11. This input unit 11 can be used to set combination conditions and the like. The combination conditions include an allowable weight range, an allowable area, and a target weight. In this embodiment, the display unit 10 and the input unit 11 are integrated, but the display unit 10 and the input unit 11 may be arranged separately.

  FIG. 2 is a side view showing a schematic configuration in the vicinity of the weighing table 2 in FIG. 1, and representatively shows one weighing table 2 out of the six weighing tables 2. In FIG. 2, parts corresponding to those in FIG.

  For convenience of explanation, as shown in FIGS. 1 and 2, the vertical direction is the z direction, and two horizontal directions perpendicular to the z direction are the x direction and the y direction.

  Each of the six weighing platforms 2 includes a corresponding load and moment detector (hereinafter referred to as a “load detector”) 12. That is, six load detectors 12 are provided for the twelve plate portions 7a and 7b.

  The weighing platform 2 provided with two plates 7a and 7b on which the objects to be weighed are placed is connected to the movable portion 13d of the strain generating body 13 constituting the load detector 12 via the legs 2a. .

  The load etc. detector 12 is obtained by adding a configuration for detecting a moment around the horizontal axis in the y direction to a robust load cell. Load detecting strain gauges A to D made of a uniaxial gauge are affixed to four strain generating portions 14 to 17 of the strain generating body 13.

  The strain generating body 13 has a fixed portion 13c and a movable portion 13d connected by a pair of beams 13a and 13b opposed to each other in the vertical direction, and cuts four places symmetrical to the top and bottom of the pair of beams 13a and 13b. It has the strain generating parts 14-17 which consist of the thin part formed by lacking.

  When the vertical load (downward force) is applied to the movable portion 13d, the strain generating body 13 applies a tensile force to the strain generating portions 14 and 17, and applies a compressive force to the strain generating portions 15 and 16. It has the characteristics of a robust type load cell.

  The moment about the horizontal axis in the y direction is a moment acting on the weighing table 2 due to the load of the object to be measured, and a predetermined application position of the strain gauges B and D (a predetermined center position of the application place). , And a moment around an axis of the horizontal axis H1 extending in the y direction (width direction of the strain generating body 13: a direction perpendicular to the paper surface of FIG. 2).

  As for the strain body 13, the edge part of the fixing | fixed part 13c is being fixed to the attachment part 3a in the flame | frame part 3 so that the longitudinal direction may turn into x direction. The two plate portions 7a and 7b are arranged such that their gravity center positions Pa and Pb are linearly arranged in the x direction.

  FIG. 3 is a block diagram showing the configuration of the combination weigher 1 in FIG. 1, and parts corresponding to those in FIG. 1 and FIG.

  As shown in FIG. 3, the four strain gauges A to D of the load detector 12 are connected to form a Wheatstone bridge circuit 18. The initial resistance value of each of the strain gauges A to D is equal to 350Ω, for example. A DC voltage V is applied between the connection point N1 of the strain gauges A and B and the connection point N3 of the strain gauges C and D, and the connection point N2 of the strain gauges A and C and the connection point of the strain gauges B and D. A potential difference signal generated between N4 and N4 is extracted, input to the A / D conversion circuit 19, converted into a digital signal (Sw), and output to the arithmetic control unit 20 and the subtraction circuit 21 of the control unit 4. The potential difference signal is a signal proportional to the magnitude (distortion amount) of the distortion generated in the beams 13a and 13b, and is a force in the z direction (vertical direction) generated by the total weight of the objects to be weighed placed on the weighing table 2. It is an analog load signal indicating (vertical load). This signal is converted into a digital load signal Sw by the A / D conversion circuit 19.

  A resistor R1 and a resistor R2 are connected in series between the connection point N1 and the connection point N3, and the strain gauges B and D and the resistors (dummy resistors) R1 and R2 constitute a Wheatstone bridge circuit. The resistance values of the resistors R1 and R2 are equal to the initial resistance values of the strain gauges B and D, for example, 350Ω. The resistance values of the resistors R1 and R2 are configured not to fluctuate. In this case, a potential difference signal generated between the connection point N4 of the strain gauges B and D and the connection point N5 of the resistors R1 and R2 is taken out, input to the A / D conversion circuit 22, converted into a digital signal, and subtracted. It is output to the circuit 21. In the subtraction circuit 21, the output signal of the A / D conversion circuit 19 is subtracted from the output signal of the A / D conversion circuit 22, and the subtraction result (Sy) is output to the arithmetic control unit 20 of the control unit 4.

  The output signal of the A / D conversion circuit 22 is a signal obtained by synthesizing the load signal component and the moment component around the y-direction horizontal axis. The load signal component is removed from this signal by the subtraction circuit 21, and the y-direction horizontal axis is output. A moment signal Sy indicating a surrounding moment component is output from the subtraction circuit 21.

  The resistors R1 and R2, the A / D conversion circuits 19 and 22 and the subtraction circuit 21 are configured by a circuit board (not shown). For example, the resistors R1 and R2 are arranged between one beam 13a and the other beam 13b of the strain generating body 13. It is installed. The DC voltage V is supplied from the control unit 4, for example.

  The control unit 4 includes the calculation control unit 20 and the memory 23 described above, and includes the display unit 10 and the input unit 11 described above. The calculation control unit 20 and the memory 23 are configured by, for example, a microcomputer.

  In the calculation control unit 20 of the control unit 4, the load signal Sw and the moment signal Sy from each load detector 12 corresponding to each weighing platform 2 are always input at predetermined time intervals, and 2 for all weighing platforms 2. The weight of the object to be weighed on each of the plate parts 7a and 7b is calculated and stored.

  Further, a combination calculation is performed based on the calculated weight of the object to be measured, and one set of combination of the dish portions in which the total weight of the objects to be weighed is within an allowable range (predetermined weight range) with respect to the target weight is obtained. The combination is regarded as an appropriate amount combination.

  When there are a plurality of combinations that are within the allowable range for the target weight, one combination of the dish portions that is the same as the target weight or closest to the target weight is selected, and the combination is set to an appropriate amount combination.

  Then, the combination lamp 8 corresponding to the dish portion selected when the appropriate amount combination is established is turned on, and the total weight (combination weight) of the objects to be weighed in the appropriate amount combination is displayed on the display unit 10.

  In the arithmetic control unit 20 of the control unit 4, the detected load W indicated by the load signal Sw from each load detector 12 corresponding to each weighing platform 2 and the moment My about the horizontal axis in the y direction indicated by the moment signal Sy. Thus, the weight of the object to be weighed placed on the two plate parts 7a and 7b of each weighing table 2 is determined as follows.

  In addition, the load (initial load) when the object to be weighed is not placed on the two plates 7a and 7b of each weighing platform 2 is detected and stored in advance, and the object to be weighed is placed. A load generated by an object to be weighed by subtracting an initial load from the load detected at 1 is set as a detected load W.

  The moment My around the horizontal axis in the y direction detected in this embodiment is the moment around the axis of the horizontal axis H1 shown in FIG. 2 described above, and the moment detection position (strain gauge) is stored in the memory 23 in the control unit 4. The barycentric positions of the respective plate portions 7a and 7b with respect to the predetermined pasting positions (B and D) are stored in advance as coordinates.

  FIG. 2 also shows coordinates (x coordinates) for the sake of explanation. The x coordinates xa, xb are the gravity center positions Pa, 7a, 7b from the moment detection position when the x coordinate of the moment detection position (predetermined application position of the strain gauges B, D) is the origin (0). This is a value based on the horizontal distance in the x direction up to Pb. Here, the x coordinate xa on the left side from the origin (0) is a negative value (the value obtained by adding a minus sign to the horizontal distance in the x direction), and the x coordinate xb on the right side from the origin (0) is a positive value. (Value of the horizontal distance in the x direction).

  In FIG. 2, the length of the weighing platform 2 having the two plate portions 7 a and 7 b is indicated by L, and the length of the intermediate region partitioned by the partition member 6 at the center is indicated by Lc.

  In this embodiment, the operator places an object to be weighed on each plate part 7 a, 7 b of each weighing table 2. The order of each weighing platform 2 and each plate portion 7a, 7b on which an object is to be weighed is not determined. Further, the operator takes out the objects to be weighed from all the plate portions 7a and 7b whose combination is established and the combination lamp 8 is lit in green, and packs them together in, for example, one bag. The total weight of the packed objects to be weighed is within the allowable range with respect to the target weight.

  First, for example, it is assumed that an object to be weighed is placed on one of the two plate parts from a state where the object to be weighed is not placed on any of the two dish parts 7a and 7b of the weighing table 2. The detected load detected at this time is W1, and the moment around the horizontal axis in the y direction detected at this time is My1.

  Here, if the vertical load that increases due to the weight wp1 of the object to be weighed is WP1, the following equation (1) holds.

WP1 = W1 (1)
If the moment about the horizontal axis in the y direction generated by the vertical load WP1 of the object to be weighed is M11 and the x coordinate of the center of gravity of the object to be weighed is X1, the following equations (2) and (3) hold.

M11 = My1 (2)
M11 = X1 · WP1 = X1 · W1 (3)
If X1 is obtained based on the above equations (2) and (3), it is as follows.

X1 = My1 / W1 (4)
In other words, the calculation control unit 20 of the control unit 4 calculates the load WP1 due to this object to be measured based on the equation (1) using the detected value W1, and converts it to the weight wp1.

  For example, it may be converted as wp1 [kg] = WP1 [N] /9.8.

  Furthermore, X1 which is the x coordinate of the center of gravity of the object to be weighed is calculated by calculating based on the equation (4) using the detection values My1 and W1.

  Then, a dish part having the x coordinate of the center of gravity (Pa, Pb) having the shortest distance from the x coordinate of the center of gravity of the object to be measured is obtained, and it is determined that the object to be weighed is placed on the dish.

  As described above, the weight and the pan portion of the object to be weighed first are obtained.

  Next, it is assumed that an object to be weighed is placed on the other plate part of the weighing table 2. The detected load detected at this time is W2, and the moment around the horizontal axis in the y direction detected at this time is My2.

  Here, if the vertical load that increases due to the current weight wp2 of the object to be weighed is WP2, the following equation (5) holds.

WP2 = W2-W1 (5)
Further, if the moment about the horizontal axis in the y direction generated by the vertical load WP2 of the current object to be weighed is M12 and the x coordinate of the center of gravity position of the current object to be weighed is X2, the following (6), (7) The formula holds.

M12 = My2-My1 (6)
M12 = X2 / WP2 = X2 (W2-W1) (7)
If X2 is obtained based on the above equations (6) and (7), it is as follows.

X2 = (My2-My1) / (W2-W1) (8)
That is, the arithmetic control unit 20 of the control unit 4 calculates the load WP2 due to the object to be measured based on the equation (5) using the detection values W1 and W2, and converts it to the weight wp2. Furthermore, X2 which is the x coordinate of the center-of-gravity position of the weighing object placed this time is obtained by calculating based on the equation (8) using the detection values My1, My2, W1, and W2. Then, a dish part having the x coordinate of the center of gravity (Pa, Pb) having the shortest distance from the x coordinate of the center of gravity of the object to be weighed is obtained, and it is determined that the object to be weighed this time is placed on the dish. As described above, the weight of the object to be weighed this time and the dish portion are obtained.

  Further, when the object to be weighed placed on the dish part is lowered, the weight of the object to be weighed down and the dish part from which the object to be weighed is lowered can be obtained. That is, when the vertical load WP2 calculated by the equation (5) is positive (when the detected load increases), it is determined that the object is placed, and when it is negative (when the detected load decreases), the object is measured. What is necessary is just to determine that has been taken down. In addition, when it is determined that the object to be weighed has been lowered, it may be determined in the same manner as when the dish portion on which the object to be weighed has been unloaded is the same.

  For each of the six weighing platforms 2, the weight of the object to be weighed and the pan portion may be obtained in the same manner.

  In this embodiment, since each weighing table 2 has two dish parts 7a and 7b, the objects to be weighed are placed on each dish part 7a and 7b twice for each weighing table 2. However, since there is a load change due to an increase in stacking, the placement of the objects to be weighed on the two dish portions 7a and 7b is not always completed by two load changes.

  Accordingly, for the third and subsequent load changes, the weights and pan portions of the objects to be weighed in sequence can be obtained in the same manner. For example, the detected load detected when the kth object is placed is Wk, and the moment about the horizontal axis in the y direction detected at this time is Myk. Further, the load detected when the first (k−1) th object to be weighed is placed on the weighing table 2 is defined as W (k−1), and the y-direction horizontal axis detected at this time is detected. Let the turning moment be My (k-1).

  Here, if the vertical load that increases due to the weight wpk of the kth object to be weighed is WPk, WPk can be obtained by the following equation (9).

WPk = Wk−W (k−1) (9)
Similarly to the case of equation (8), if the x coordinate of the gravity center position of the k-th object to be weighed is Xk, Xk is obtained by the following equation (10).

Xk = (Myk−My (k−1)) / (Wk−W (k−1)) (10)
Further, when the object to be weighed placed on the dish part is lowered, the weight of the object to be weighed down and the dish part from which the object to be weighed is lowered can be obtained. That is, when the vertical load WPk calculated by the equation (9) is positive (when the detected load increases), it is determined that the object is placed, and when it is negative (when the detected load decreases), the object is measured. What is necessary is just to determine that was taken down. In addition, when it is determined that the object to be weighed has been lowered, it may be determined in the same manner as when the dish portion on which the object to be weighed has been unloaded is the same.

  As described above, when the detected load increases or decreases, that is, when the detected load changes, the arithmetic control unit 20 of the control unit 4 detects the amount of change in the detected load as described above. Based on the moment change amount, the position of the center of gravity of the object to be weighed is obtained and the object 7 on which the object to be weighed is placed or lowered is obtained, and the weight of the object to be weighed is obtained.

  The processing after obtaining the weights of the objects to be weighed by obtaining the plates 7a and 7b on which the objects to be weighed are placed or lowered is basically the same as the processing of the conventional combination weigher. For example, after obtaining the weight of the pan on which the object is to be weighed and the weight of the object to be weighed, perform a combination operation, and after obtaining the weight of the pan and the object to be weighed off, For example, it is determined whether or not the combination lamp corresponding to the dish part where the object to be weighed is lowered is lit. A process of turning off the lamp is performed, and the weight of the object to be weighed and the dish part on which the object to be weighed and the object to be weighed are loaded or lowered are obtained based on the load signal Sw and the moment signal Sy input at predetermined time intervals. Repeat the process.

  In this embodiment, the weight of each object to be weighed on the two plate portions 7a and 7b can be measured by one load detector 12 or the like. Since this load detector 12 only adds a configuration for detecting a moment around the horizontal axis in the y-direction to a single load-type load cell, the manufacturing cost can be reduced without using a plurality of load cells. Reduction can be achieved.

  In the manual combination weigher as in this embodiment, the operator places an object to be weighed on one of the two plates 7a and 7b of the weighing table 2, and at the same time the other plate There is a case where the so-called simultaneous unloading of the objects to be weighed off occurs.

  In such a case, the x-coordinate which is the center of gravity position of the object to be measured cannot be calculated correctly, and as a result, an error occurs in which the correct weight values of the two dish parts 7a and 7b cannot be obtained.

  Here, the simultaneous loading and unloading means that the object to be weighed is dropped from the state in which the object to be weighed is placed on one dish part 7a (or 7b), and the object to be weighed is placed on the other dish part 7b (or 7a). The balance is stable within the period until it is placed, or within the period from when the object to be weighed is placed on one dish part 7a (or 7b) to when the object to be weighed on the other dish part 7b (or 7a) is lowered. The change in load when the object to be weighed is lowered from one dish part 7a (or 7b) or the object to be weighed is placed on one dish part 7a (or 7b). The case where it was not detected. The simultaneous loading and unloading includes a case where the object to be weighed on one plate portion 7a (or 7b) is moved to the other plate portion 7b (or 7a) within a period in which the balance cannot be stabilized.

  In this embodiment, such simultaneous loading and unloading is detected as follows.

  That is, a range in which the object to be measured can be placed is set in advance. When simultaneous loading / unloading occurs, the position of the center of gravity of the object to be measured, which is obtained from the difference between the weight value and the moment value at that time, becomes a position that exceeds the range in which the object can be placed. Using this, it is determined that simultaneous loading / unloading has occurred.

  In this embodiment, as shown in FIG. 2 described above, the total length of the weighing table 2 is L, and the central area Lc of the weighing table 2 partitions the left and right plate portions 7a and 7b in the middle and also places the object to be weighed. This is a placement prohibited area where placement is prohibited. In the x-axis that defines the position of the center of gravity of the object to be weighed, the center of the weighing platform 2 is the origin 0, the right side is positive, and the left side is negative.

  Here, for example, as shown in FIGS. 4A and 4B, a case is assumed where placing the object to be weighed 24A and dropping the object to be weighed 24B occur simultaneously. First, as shown in FIG. 4A, an object to be weighed 24B having a weight WB was placed at the position LB, which is the center of the right plate part 7b. Simultaneously with lowering this, another object to be weighed 24A having a weight WA is placed at the position LA (assuming LA = −LB). In addition, moments viewed from the origin 0 are defined as MA and MB, respectively. At this time, the respective center-of-gravity positions are expressed as LA = MA / WA and LB = MB / WB. Although the relationship between MA and MB, the change in each moment is symmetric with respect to the origin, so MB = MA (because LB = LA).

  At this time, since simultaneous loading / unloading has occurred, the arithmetic control unit 20 of the control unit 4 recognizes that the weight has changed by WA-WB. A change ΔM in the moment amount at this time is MA-MB.

Now, assume that there is not much difference between WA and WB, and WA = 0.8 WB. At this time, ΔW = WA−WB = −0.2 WB, but ΔM changes by ΔM = MA−MB = −2 MB. From these, when calculating the center of gravity position due to this weight change,
X = (MA−MB) / (WA−WB) = ΔM / ΔW = −2 MB / −0.2 WB = 10 MB / WB
It becomes the position. Here, since LB = MB / WB, X = 10 LB.

  This is an apparent change in weight recognized by the arithmetic control unit 20 of the control unit 4 at the time of simultaneous loading and unloading, and is visualized as shown in FIG.

  Since LB is the center of the dish part, the position of X> 2LB will be outside the dish part.

  Therefore, when X = 10LB, it can be recognized that the object to be weighed is placed at a position far from the plate portion. Since this is a phenomenon that is naturally not possible, the arithmetic control unit 20 of the control unit 4 can determine that simultaneous loading / unloading has occurred by looking at the relative change amount.

  In a general scale of about 1/3000, when the count value after A / D conversion changes by several counts, the change in the moment amount becomes very small, and the difference in the weight of the objects to be weighed due to simultaneous loading and unloading, When there are only a few counts, an accurate value cannot be obtained with the resolution of A / D conversion.

  For this reason, when the position of the center of gravity is obtained from the moment value, an error of about several hundred millimeters occurs. Therefore, in the case of a slight change in weight, it is not easy to obtain the position of the center of gravity of the object to be weighed.

  Therefore, in this embodiment, in the case of a slight change in weight, it is detected from the absolute center of gravity position before and after the change in weight that the simultaneous loading / unloading has occurred.

For example, as shown in FIG. 4A, the first center of gravity position is + LB, and the next center of gravity position is LA = −LB as shown in FIG. 4B. Here, when the product of the front and rear barycentric positions is obtained, it becomes negative with −LB ² , so that it can be seen that the barycentric position has moved to another plate part. That is, when the change in weight is small, the sign of the product of the x-coordinates before and after the change in weight is negative, and it is determined that simultaneous loading / unloading has occurred when the entire center of gravity position has moved to another dish. can do.

  For this reason, in this embodiment, the control unit 4 determines whether or not the x-coordinate that is the center of gravity position is within the plates 7a and 7b, which are the mountable ranges, when the weight change is greater than a certain value. If the weight change is not more than a certain value, that is, if the weight change is small, the simultaneous loading will occur depending on whether the x-coordinate product before and after the weight change is negative. Whether or not there is is determined.

  The above processing is shown in the flowchart of FIG.

  First, the output signals Sw and Sy of each load etc. detector 12 of each weighing platform 2 are received and the weight value and moment value are taken in (step S1), and whether or not there is a change in the weight value for all the weighing platforms 2 (Step S2), and if there is a change in the weight value, based on the change in the weight and the moment of the weighing table 2, the X-coordinate which is the center of gravity position corresponding to the change in weight as described above Is calculated (step S3), and it is determined whether the weight change is equal to or greater than a certain value (step S4).

  If the weight change is greater than or equal to a certain value in step S4, it is determined whether or not the x-coordinate that is the center of gravity position is inside the dish part (step S5), and if the center of gravity position is inside the dish part, The amount of weight change is added to the weight value of the existing plate (step S6), and the process proceeds to step S10. In step S10, after obtaining the weight of the pan and the object to be weighed in normal processing, for example, the combination operation is performed, and the dish and the object to be weighed are taken down. After obtaining the weight of the object, for example, it is determined whether or not the combination lamp corresponding to the dish part on which the object to be weighed is lowered is lit. Processing is performed such that the combination lamp is turned off because the weighing object has been lowered, and the process returns to step S1 again.

  In step 5, when the x-coordinate which is the center of gravity position is not inside the dish part, it is determined that they are simultaneously loaded and unloaded, and error processing described later is executed (step S7).

  In step S4, when the weight change is not more than a certain value, it is determined whether or not the product of the x-coordinates that are the center of gravity positions before and after the weight change is negative (step S8). It is determined that there is an error, and an error process described later is executed (step S7). If not negative, the process returns to step S1 without updating the weight (step S9).

  Here, error processing will be described.

  In an error state such as simultaneous loading and unloading, the correct weight values of the two plates 7a and 7b are not known.

  Therefore, in such an error state, in order to notify the operator of the error, for example, the combination lamps 8a and 8b corresponding to the two plates 7a and 7b of the weighing platform 2 in which the error has occurred blinks in red. , Buzzer will alert you. As a result, the operator temporarily lowers the objects to be weighed on the two dish parts 7a and 7b, and sets the weights of both the dish parts 7a and 7b to “0” g and remounts the objects to be weighed. As a result, the weights of the objects to be weighed in the respective plate portions 7a and 7b are reset, and the error is released.

  However, it is inefficient for the operator to unload and reload the objects to be weighed from the two plates 7a and 7b each time an error occurs.

  Therefore, in this embodiment, the following is performed in order to increase work efficiency.

  That is, in this embodiment, when an error is detected when simultaneous loading / unloading is performed, the control unit 4 collects the entire weighing platform 2 that has detected the error, that is, the two plate portions 7a and 7b of the weighing platform 2 together. The entire plate portions 7a and 7b are regarded as one plate portion and are allowed to participate in the combination calculation. When the two dish parts 7a and 7b are put together, the control unit 4 turns on an integrated flag indicating that the two tray parts 7a and 7b are put together, and the combination lamps 8a and 8b respectively corresponding to the integrated two dish parts 7a and 7b. The same command is output to 8b. For example, when the combination is established and the green lighting display for removing the object to be weighed is performed, the combination is performed with respect to the two combination lamps 8a and 8b respectively corresponding to the two dish portions 7a and 7b. A green lighting display command indicating establishment is output.

  When the weight of the two integrated plate portions 7a and 7b reaches “0” g as a whole, the control unit 4 regards the entire two integrated plate portions 7a and 7b as one plate portion, for example. When the combination is established by the combination calculation performed and all the objects to be weighed in the two plates 7a and 7b are lowered, the integration is canceled and the integration flag is turned off, and each plate 7a is set one by one. , 7b and participate in the combination calculation, that is, cancel the error and return.

(Embodiment 2)
In the above-described embodiment, every time the weight value from the load detector 12 changes, the arithmetic control unit 20 of the control unit 4 changes the weight value from the change amount of the weight value and the change amount of the moment amount. The x coordinate which is the corresponding center of gravity position is calculated. Then, the current change in the weight value is added as an additional amount to the weight of the plate portion having the x-coordinate which is the center of gravity position.

  In such a configuration, an object to be weighed of the same weight is placed on one plate part at the same time as it is lowered from the other plate part, or an object to be weighed of the same weight is loaded from one plate part to the other dish. Simultaneous loading and unloading such as quick movement to the part cannot be detected because the weight value does not change.

  Therefore, in this embodiment, the following is performed so that the simultaneous loading and unloading of the objects to be weighed can be detected even if there is no change in the weight value.

  That is, the change in the moment value is monitored together with the weight value, and even if the weight value does not change, if the moment value changes, the position of the center of gravity obtained therefrom also changes. Therefore, by determining whether or not the position of the center of gravity has moved to another plate portion before and after the change of the moment value, it is possible to detect that the simultaneous loading / unloading of the objects to be weighed as described above has occurred. .

  FIG. 7 is a flowchart for explaining the operation of this embodiment.

  First, the output signals Sw and Sy of each load etc. detector 12 of each weighing platform 2 are received and the weight value and moment value are taken in (step S1), and whether or not there is a change in the weight value for all the weighing platforms 2 Is determined (step S2), and if there is a change in the weight value, the process proceeds to step S3 in FIG. 6 described above, and thereafter the same processing as in FIG. 6 is performed.

  When there is no change in the weight value in step S2 in FIG. 7, it is determined whether or not there is a change in the moment value (step S3). When there is a change in the moment value, the center of gravity position is determined based on the weight and the moment value. X coordinate is calculated (step S4), and it is determined whether or not the x coordinate which is the center of gravity position has moved from one dish part to the other dish part (step S5), and the x coordinate is determined from one dish part to the other. When moving to the pan portion, the above-described error processing is executed on the assumption that simultaneous loading / unloading of objects to be weighed of the same weight has occurred (step S6).

  Other configurations are the same as those of the above-described embodiment.

( Reference example )
In each of the above-described embodiments, every time the weight value from the load detector 12 changes, the arithmetic control unit 20 of the control unit 4 changes the weight value from the change amount of the weight value and the change amount of the moment amount. X-coordinate which is the barycentric position corresponding to is calculated. Then, the current change in the weight value is added as an additional amount to the weight of the plate portion having the x-coordinate which is the center of gravity position.

  When the change in the weight value is only a few counts after the A / D conversion, as described above, the change in the moment amount becomes very small with a general scale of about 1/3000. It is difficult to obtain the position of the center of gravity of the object to be weighed.

Therefore, in this reference example , when the object to be weighed is placed only on one of the plates, and the weight changes slightly due to flickering such as vibration, the plate of the object to be weighed is placed. It is determined that the weight has flickered, and the weight is updated in real time by adding the minutely changed weight to the weight of the dish without obtaining the position of the center of gravity. However, if the amount of change is large enough to accurately determine the position of the center of gravity, the x-coordinate that is the position of the center of gravity of the object to be weighed based on the weight value and the moment value, as in the above embodiments. Ask for.

FIG. 8 is a flowchart for explaining the operation of this reference example .

  First, the output signals Sw and Sy of each load etc. detector 12 of each weighing platform 2 are received and the weight value and moment value are taken in (step S1), and whether or not there is a change in the weight value for all the weighing platforms 2 (Step S2), and if there is a change in the weight value, based on the change in the weight and the moment of the weighing table 2, the X-coordinate which is the center of gravity position corresponding to the change in weight as described above Is calculated (step S3), and it is determined whether or not the weight change is equal to or less than a certain weight corresponding to a minute weight change due to flickering such as vibration (step S4).

  When the change in weight is not more than a certain weight, the x-coordinate which is the center of gravity position cannot be calculated accurately. Therefore, whether or not only one dish part has weight without calculating the x-coordinate, that is, one dish part. It is determined whether or not an object to be weighed is placed (step S5). If only one dish part has a weight, the weight change is added to the weight value of the heavy dish part and step S9. (Step S6).

  In step S9, after obtaining the weight of the pan and the object to be weighed in a normal process, for example, the combination operation is performed, and the dish and the object to be weighed are taken down. After obtaining the weight of the object, for example, it is determined whether or not the combination lamp corresponding to the dish part on which the object to be weighed is lowered is lit. Processing is performed such that the combination lamp is turned off because the weighing object has been lowered, and the process returns to step S1.

  In step S5, when only one dish part has no weight, the process proceeds to step S9 without updating the weight (step S7). In step S4, if the change in weight is not equal to or less than a certain weight, the process proceeds to step S9 after performing processing such as which plate portion has the x-coordinate which is the center of gravity calculated in step S3 (step S8). Other configurations are the same as those of the above-described embodiment.

  Unlike the above-described embodiments, even when there are two or more dish parts of the weighing platform 2, it is possible to detect the load position by determining which dish part has the X coordinate of the center of gravity position. Become.

  The present invention is useful as a combination weigher.

DESCRIPTION OF SYMBOLS 1 Combination scale 2 Weighing base 4 Control unit 7a, 7b Plate part 8, 8a, 8b Combination lamp 12 Load etc. detector

Claims (6)

A plurality of weighing platforms each having two placement parts on which objects to be weighed are placed;
A plurality of load detectors for detecting the load of each weighing platform,
A plurality of moment detecting means for detecting each moment acting on each weighing table by the load;
Based on the detection output of the load detector, the weight of the object to be weighed placed on the placement unit is obtained, and on the placement unit based on the detection output of the load detector and the moment detection means. The center of gravity position of the object to be weighed placed or lowered from the placement unit is obtained, and the object to be weighed is placed or lowered based on the obtained center of gravity position and the center of gravity position of the placement unit. Calculating means for obtaining the above-described placement portion;
A combination weigher comprising a combination calculation means for performing a combination calculation based on the weight of the object to be weighed and the placement portion obtained by the calculation means,
The object to be weighed is placed on one placing part of the two placing parts and the object to be weighed on the other placing part is lowered simultaneously, or the object to be weighed on one placing part is lowered and the other A combination weigher comprising error detection means for detecting a simultaneous loading / unloading as an error for placing an object to be weighed on a mounting portion.   The combination according to claim 1, wherein the error detection unit determines that the simultaneous loading and unloading is performed when a gravity center position of the object to be weighed obtained by the calculation unit is not in an area corresponding to the two placement units. Scale.   The barycentric positions of the two mounting parts of each weighing platform are arranged in a straight line, and the error detection means uses the intermediate position of the two mounting parts as the origin of coordinates, and one mounting part When the side is positive and the other mounting part side is negative, the weight change of the two mounting parts is smaller than a predetermined value, and the measurement object is obtained by the calculation means before and after the weight change. The combination weigher according to claim 1 or 2, wherein when the product of the coordinates of the center of gravity position of the object is negative, the simultaneous loading / unloading is determined. The calculation means is for obtaining the position of the center of gravity of the object to be weighed when there is no change in load and there is a change in moment.
The said error detection means determines the presence or absence of simultaneous loading / unloading based on the change of the gravity center position of the said to-be-measured object, when there is no change of a load and there is a change of a moment. Combination weigher. When an error of simultaneous loading / unloading is detected by the error detection means, the combination calculation means combines the two placement parts of the weighing platform in which the error has been detected and combines them as one placement part. Perform calculations,
The combination weigher according to claim 1. When all the objects to be weighed in the two placement parts of the weighing table in which the error has been detected have been lowered, the combination calculation means has the two placement parts of the weighing table in which the error has been detected. To unify and perform a combination operation as two mounting parts,
The combination weigher according to claim 5 .

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